Novel breast cancer susceptibility loci under linkage peaks identified in African ancestry consortia

BACKGROUND

Expansion of genome-wide association studies across population groups is needed to improve our understanding of shared and unique genetic contributions to breast cancer. We performed association and replication studies guided by a priori linkage findings from African ancestry (AA) relative pairs.

METHODS

We performed fixed-effect inverse-variance weighted meta-analysis under three significant AA breast cancer linkage peaks (3q26-27, 12q22-23, and 16q21-22) in 9241 AA cases and 10 193 AA controls. We examined associations with overall breast cancer as well as estrogen receptor (ER)-positive and negative subtypes (193,132 SNPs). We replicated associations in the African-ancestry Breast Cancer Genetic Consortium (AABCG).

RESULTS

In AA women, we identified two associations on chr12q for overall breast cancer (rs1420647, OR = 1.15, p = 2.50×10-6; rs12322371, OR = 1.14, p = 3.15×10-6), and one for ER-negative breast cancer (rs77006600, OR = 1.67, p = 3.51×10-6). On chr3, we identified two associations with ER-negative disease (rs184090918, OR = 3.70, p = 1.23×10-5; rs76959804, OR = 3.57, p = 1.77×10-5) and on chr16q we identified an association with ER-negative disease (rs34147411, OR = 1.62, p = 8.82×10-6). In the replication study, the chr3 associations were significant and effect sizes were larger (rs184090918, OR: 6.66, 95% CI: 1.43, 31.01; rs76959804, OR: 5.24, 95% CI: 1.70, 16.16).

CONCLUSION

The two chr3 SNPs are upstream to open chromatin ENSR00000710716, a regulatory feature that is actively regulated in mammary tissues, providing evidence that variants in this chr3 region may have a regulatory role in our target organ. Our study provides support for breast cancer variant discovery using prioritization based on linkage evidence.

Epigenetic disruption of the RARγ complex impairs its function to bookmark AR enhancer interactions required for enzalutamide sensitivity in prostate cancer

The current study in prostate cancer (PCa) focused on the genomic mechanisms at the cross-roads of pro-differentiation signals and the emergence of lineage plasticity. We explored an understudied cistromic mechanism involving RARγ's ability to govern AR cistrome-transcriptome relationships, including those associated with more aggressive PCa features. The RARγ complex in PCa cell models was enriched for canonical cofactors, as well as proteins involved in RNA processing and bookmarking. Identifying the repertoire of miR-96 bound and regulated gene targets, including those recognition elements marked by m6A, revealed their significant enrichment in the RARγ complex. RARγ significantly enhanced the AR cistrome, particularly in active enhancers and super-enhancers, and overlapped with the binding of bookmarking factors. Furthermore, RARγ expression led to nucleosome-free chromatin enriched with H3K27ac, and significantly enhanced the AR cistrome in G2/M cells. RARγ functions also antagonized the transcriptional actions of the lineage master regulator ONECUT2. Similarly, gene programs regulated by either miR-96 or antagonized by RARγ were enriched in alternative lineages and more aggressive PCa phenotypes. Together these findings reveal an under-investigated role for RARγ, modulated by miR-96, to bookmark enhancer sites during mitosis. These sites are required by the AR to promote transcriptional competence, and emphasize luminal differentiation, while antagonizing ONECUT2.

Associations of minor histocompatibility antigens with outcomes following allogeneic hematopoietic cell transplantation

The role of minor histocompatibility antigens (mHAs) in mediating graft versus leukemia and graft versus host disease (GvHD) following allogeneic hematopoietic cell transplantation (alloHCT) is recognized but not well-characterized. By implementing improved methods for mHA prediction in two large patient cohorts, this study aimed to comprehensively explore the role of mHAs in alloHCT by analyzing whether (1) the number of predicted mHAs, or (2) individual mHAs are associated with clinical outcomes. The study population consisted of 2249 donor-recipient pairs treated for acute myeloid leukemia and myelodysplastic syndrome with alloHCT. A Cox proportional hazard model showed that patients with a class I mHA count greater than the population median had an increased hazard of GvHD mortality (hazard ratio [HR] = 1.39, 95% confidence interval [CI] = 1.01, 1.77, p = .046). Competing risk analyses identified the class I mHAs DLRCKYISL (GSTP), WEHGPTSLL (CRISPLD2), and STSPTTNVL (SERPINF2) were associated with increased GVHD mortality (HR = 2.84, 95% CI = 1.52, 5.31, p = .01), decreased leukemia-free survival (LFS) (HR = 1.94, 95% CI = 1.27, 2.95, p = .044), and increased disease-related mortality (DRM) (HR = 2.32, 95% CI = 1.5, 3.6, p = .008), respectively. One class II mHA YQEIAAIPSAGRERQ (TACC2) was associated with increased risk of treatment-related mortality (TRM) (HR = 3.05, 95% CI = 1.75, 5.31, p = .02). WEHGPTSLL and STSPTTNVL were both present within HLA haplotype B*40:01-C*03:04 and showed a positive dose-response relationship with increased all-cause mortality and DRM and decreased LFS, indicating these two mHAs contribute to the risk of mortality in an additive manner. Our study reports the first large-scale investigation of the associations of predicted mHA peptides with clinical outcomes following alloHCT.

African American Prostate Cancer Displays Quantitatively Distinct Vitamin D Receptor Cistrome-transcriptome Relationships Regulated by BAZ1A

African American (AA) prostate cancer associates with vitamin D₃ deficiency, but vitamin D receptor (VDR) genomic actions have not been investigated in this context. We undertook VDR proteogenomic analyses in European American (EA) and AA prostate cell lines and four clinical cohorts. Rapid immunoprecipitation mass spectrometry of endogenous protein (RIME) analyses revealed that nonmalignant AA RC43N prostate cells displayed the greatest dynamic protein content in the VDR complex. Likewise, in AA cells, Assay for Transposase-Accessible Chromatin using sequencing established greater 1α,25(OH)₂D₃-regulated chromatin accessibility, chromatin immunoprecipitation sequencing revealed significant enhancer-enriched VDR cistrome, and RNA sequencing identified the largest 1α,25(OH)₂D₃-dependent transcriptome. These VDR functions were significantly corrupted in the isogenic AA RC43T prostate cancer cells, and significantly distinct from EA cell models. We identified reduced expression of the chromatin remodeler, BAZ1A, in three AA prostate cancer cohorts as well as RC43T compared with RC43N. Restored BAZ1A expression significantly increased 1α,25(OH)₂D₃-regulated VDR-dependent gene expression in RC43T, but not HPr1AR or LNCaP cells. The clinical impact of VDR cistrome-transcriptome relationships were tested in three different clinical prostate cancer cohorts. Strikingly, only in AA patients with prostate cancer, the genes bound by VDR and/or associated with 1α,25(OH)₂D₃-dependent open chromatin (i) predicted progression from high-grade prostatic intraepithelial neoplasia to prostate cancer; (ii) responded to vitamin D3 supplementation in prostate cancer tumors; (iii) differentially responded to 25(OH)D3 serum levels. Finally, partial correlation analyses established that BAZ1A and components of the VDR complex identified by RIME significantly strengthened the correlation between VDR and target genes in AA prostate cancer only. Therefore, VDR transcriptional control is most potent in AA prostate cells and distorted through a BAZ1A-dependent control of VDR function.

Significance

Our study identified that genomic ancestry drives the VDR complex composition, genomic distribution, and transcriptional function, and is disrupted by BAZ1A and illustrates a novel driver for AA prostate cancer.

Polygenic risk scores for prediction of breast cancer risk in women of African ancestry: a cross-ancestry approach

Polygenic risk scores (PRSs) are useful for predicting breast cancer risk, but the prediction accuracy of existing PRSs in women of African ancestry (AA) remains relatively low. We aim to develop optimal PRSs for the prediction of overall and estrogen receptor (ER) subtype-specific breast cancer risk in AA women. The AA dataset comprised 9235 cases and 10 184 controls from four genome-wide association study (GWAS) consortia and a GWAS study in Ghana. We randomly divided samples into training and validation sets. We built PRSs using individual-level AA data by a forward stepwise logistic regression and then developed joint PRSs that combined (1) the PRSs built in the AA training dataset and (2) a 313-variant PRS previously developed in women of European ancestry. PRSs were evaluated in the AA validation set. For overall breast cancer, the odds ratio per standard deviation of the joint PRS in the validation set was 1.34 [95% confidence interval (CI): 1.27-1.42] with the area under receiver operating characteristic curve (AUC) of 0.581. Compared with women with average risk (40th-60th PRS percentile), women in the top decile of the PRS had a 1.98-fold increased risk (95% CI: 1.63-2.39). For PRSs of ER-positive and ER-negative breast cancer, the AUCs were 0.608 and 0.576, respectively. Compared with existing methods, the proposed joint PRSs can improve prediction of breast cancer risk in AA women.

Abstract 3619: Vitamin D receptor function in African American prostate cancer is disrupted by reduced BAZ1A/SMARCA5

The biological drivers of prostate cancer (PCa) health disparities remain enigmatic. There are genomic differences, for example in the incidence of TMPRSS2 and ERG gene fusions which differ between European American (EA) and African American (AA) PCa. Accumulating epidemiological evidence suggests loss of vitamin D receptor VDR signaling contributes to AA PCa. Therefore, we investigated the VDR signaling in AA and EA prostate models. VDR protein levels were comparable between AA (RC43N, RC43T, RC77N, RC77T) and EA cells (HPr1AR, LNCaP) but RIME analyses identified significant AA-EA differences in VDR binding of coactivators (e.g. NCOA5), corepressors (e.g. HDAC2), and components of SWI/SNF and circadian rhythm complexes. ATAC-Seq identified 1α,25(OH)2D3-stimulated gain in nucleosome free (NF) regions was greatest in RC43N (non-malignant AA cells) and enriched for circadian rhythm transcription motifs (e.g. CLOCK). In RC43T AA PCa cells 1α,25(OH)2D3 led to a loss of NF free regions. Similarly, VDR ChIP-Seq revealed the cistrome was greater in AA cell models, and was dynamically altered in RC43N cells by 1α,25(OH)2D3 and overlapped with the SWI/SNF component SMARCA4, but 1α,25(OH)2D3 led to reduced VDR binding in RC43T cells. The 1α,25(OH)2D3-regulated transcriptome was largest in RC43N and RC43T but GSEA terms were frequently and oppositely enriched, for example Reactome S phase genes were negatively enriched in RC43N, but positively enriched in RC43T. Cistrome-transcriptome integration identified the most significant relationships between VDR binding and the magnitude of 1α,25(OH)2D3-regulated genes in RC43N. Global coregulator analyses identified significantly reduced BAZ1A/SMARCA5 in AA PCa in TCGA and a published cohort of ~1500 AA/EA tumors. Restoring BAZ1A expression in cells resulted in significantly enhanced 1α,25(OH)2D3-regulated transcriptome in RC43N and RC43T cells, and hypergeometric tests revealed the significant enrichment of direct VDR target genes. The footprint of altered AA VDR signaling was evident in three previously established clinical cohorts. Serum miRNA that predicted AA progression from HGPIN to PCa were enriched for 1α,25(OH)2D3-regulated VDR targets; AA tumors from a vitaminD3-treated chemotherapy trail were enriched for VDR-bound genes; and, tumors from men with low serum 25(OH)D3 levels were significantly enriched for VDR target genes identified in AA but not EA PCa. Together, these data suggest VDR transcriptional control is most potent and dynamic in AA prostate cells, and is primed to govern inflammatory and circadian pathways. Reduced BAZ1A/SMARCA5 expression and/or reduced environmental-regulated serum vitamin D3 levels most acutely suppress these actions in AA PCa. Therefore, the VDR axis lies at the cross-roads of biopsychosocial processes that contributes to PCa health disparities.

Citation Format: Shahid Hussain, Manjunath Siddappa, Sajad A. Wani, Hedieh Jafari, Jaimie S. Gray, Hsu-Chang Wu, Hancong Tang, Mark D. Long, Isra Elhussin, Balasubramanyam Karanam, Honghe Wang, Rebecca Morgan, Gary Hardiman, Isaacson B. Adelani, Rotimi Oladapo, Adam R. Murphy, James R. Marshall, Chanita Highes Halbert, Lara E. Sucheston-Campbell, Clayton Yates, Moray J. Campbell. Vitamin D receptor function in African American prostate cancer is disrupted by reduced BAZ1A/SMARCA5 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3619.

Novel genetic variants associated with mortality after unrelated donor allogeneic hematopoietic cell transplantation

BACKGROUND

Identification of non-human leukocyte antigen (HLA) genetic risk factors could improve survival after allogeneic blood or marrow transplant (BMT) through matching at additional loci or individualizing risk prediction. We hypothesized that non-HLA loci contributed significantly to 1-year overall survival (OS), disease related mortality (DRM) or transplant related mortality (TRM) after unrelated donor (URD)BMT.

METHODS

We performed a genome-wide association study (GWAS) in 2,887 acute myeloid leukemia (AML), myelodysplastic syndrome (MDS) and acute lymphoblastic leukemia (ALL) patients and their ≥8/8 HLA-matched URDs comprising two independent cohorts treated from 2000-2011.

FINDINGS

Using meta-analyses of both cohorts, genome-wide significant associations (p < 5 × 10^-8) were identified in: recipient genomes with OS at MBNL1 (rs9990017, HR = 1.4, 95% CI 1.24-1.56, p = 3.3 × 10^-8) and donor-recipient genotype mismatch with OS at LINC02774 (rs10927108, HR = 1.34, 95% CI 1.21-1.48, p = 2.0 × 10^-8); donor genomes with DRM at PCNX4 (rs79076914, HR = 1.7, 95% CI 1.41-2.05, p = 3.15 × 10^-8), LINC01194 (rs79498125, HR = 1.86, 95% CI 1.49-2.31, p = 2.84 × 10^-8), ARID5B (rs2167710, HR = 1.5, 95% CI 1.31-1.73, p = 6.9 × 10^-9) and CT49 (rs32250, HR = 1.44, 95% CI1.26-1.64, p = 2.6 × 10^-8); recipient genomes at PILRB with TRM (rs141591562, HR = 2.33, 95% CI 1.74-3.12, p = 1.26 × 10^-8) and donor-recipient genotype mismatch between EPGN and MTHF2DL with TRM (rs75868097, HR = 2.66, 95% CI 1.92-3.58, p = 4.6 × 10^-9). Results publicly available at https://fuma.ctglab.nl/browse.

INTERPRETATION

These data provide the first evidence that non-HLA common genetic variation at novel loci with biochemical function significantly impacts 1-year URD-BMT survival. Our findings have implications for donor selection, could guide treatment strategies and provide individualized risk prediction after future validation and functional studies.

FUNDING

This project was funded by grants from the National Institutes of Health, USA.

Evaluating Polygenic Risk Scores for Breast Cancer in Women of African Ancestry

BACKGROUND

Polygenic risk scores (PRSs) have been demonstrated to identify women of European, Asian, and Latino ancestry at elevated risk of developing breast cancer (BC). We evaluated the performance of existing PRSs trained in European ancestry populations among women of African ancestry.

METHODS

We assembled genotype data for women of African ancestry, including 9241 case subjects and 10 193 control subjects. We evaluated associations of 179- and 313-variant PRSs with overall and subtype-specific BC risk. PRS discriminatory accuracy was assessed using area under the receiver operating characteristic curve. We also evaluated a recalibrated PRS, replacing the index variant with variants in each region that better captured risk in women of African ancestry and estimated lifetime absolute risk of BC in African Americans by PRS category.

RESULTS

For overall BC, the odds ratio per SD of the 313-variant PRS (PRS313) was 1.27 (95% confidence interval [CI] = 1.23 to 1.31), with an area under the receiver operating characteristic curve of 0.571 (95% CI = 0.562 to 0.579). Compared with women with average risk (40th-60th PRS percentile), women in the top decile of PRS313 had a 1.54-fold increased risk (95% CI = 1.38-fold to 1.72-fold). By age 85 years, the absolute risk of overall BC was 19.6% for African American women in the top 1% of PRS313 and 6.7% for those in the lowest 1%. The recalibrated PRS did not improve BC risk prediction.

CONCLUSION

The PRSs stratify BC risk in women of African ancestry, with attenuated performance compared with that reported in European, Asian, and Latina populations. Future work is needed to improve BC risk stratification for women of African ancestry.

Prognostic impact of pre-transplant chromosomal aberrations in peripheral blood of patients undergoing unrelated donor hematopoietic cell transplant for acute myeloid leukemia

To improve risk stratification and treatment decisions for patients with acute myeloid leukemia (AML) undergoing hematopoietic cell transplantation (HCT). We used SNP-array data from the DISCOVeRY-BMT study to detect chromosomal aberrations in pre-HCT peripheral blood (collected 2–4 weeks before the administration of conditioning regimen) from 1974 AML patients who received HCT between 2000 and 2011. All aberrations detected in ≥ 10 patients were tested for their association with overall survival (OS), separately by remission status, using the Kaplan–Meier estimator. Cox regression models were used for multivariable analyses. Follow-up was through January 2019. We identified 701 unique chromosomal aberrations in 285 patients (7% of 1438 in complete remission (CR) and 36% of 536 not in CR). Copy-neutral loss-of-heterozygosity (CNLOH) in chr17p in CR patients (3-year OS = 20% vs. 50%, with and without chr17p CNLOH, p = 0.0002), and chr13q in patients not in CR (3-year OS = 4% vs. 26%, with and without chr13q CNLOH, p < 0.0001) are risk factors for poor survival. Models adjusted for clinical factors showed approximately three-fold excess risk of post-HCT mortality with chr17p CNLOH in CR patients (hazard ratio, HR = 3.39, 95% confidence interval CI 1.74–6.60, p = 0.0003), or chr13q CNLOH in patients not in CR (HR = 2.68, 95% CI 1.75–4.09, p < 0.0001). The observed mortality was mostly driven by post-HCT relapse (HR = 2.47, 95% CI 1.01–6.02, p = 0.047 for chr17p CNLOH in CR patients, and HR = 2.58, 95% CI 1.63–4.08, p < 0.0001 for chr13q CNLOH in patients not in CR. Pre-transplant CNLOH in chr13q or chr17p predicts risk of poor outcomes after unrelated donor HCT in AML patients. A large prospective study is warranted to validate the results and evaluate novel strategies to improve survival in those patients.

Cross-ancestry GWAS meta-analysis identifies six breast cancer loci in African and European ancestry women

Our study describes breast cancer risk loci using a cross-ancestry GWAS approach. We first identify variants that are associated with breast cancer at P < 0.05 from African ancestry GWAS meta-analysis (9241 cases and 10193 controls), then meta-analyze with European ancestry GWAS data (122977 cases and 105974 controls) from the Breast Cancer Association Consortium. The approach identifies four loci for overall breast cancer risk [1p13.3, 5q31.1, 15q24 (two independent signals), and 15q26.3] and two loci for estrogen receptor-negative disease (1q41 and 7q11.23) at genome-wide significance. Four of the index single nucleotide polymorphisms (SNPs) lie within introns of genes (KCNK2, C5orf56, SCAMP2, and SIN3A) and the other index SNPs are located close to GSTM4, AMPD2, CASTOR2, and RP11-168G16.2. Here we present risk loci with consistent direction of associations in African and European descendants. The study suggests that replication across multiple ancestry populations can help improve the understanding of breast cancer genetics and identify causal variants.

Genome-Wide Association Analyses Identify Variants in IRF4 Associated With Acute Myeloid Leukemia and Myelodysplastic Syndrome Susceptibility

The role of common genetic variation in susceptibility to acute myeloid leukemia (AML), and myelodysplastic syndrome (MDS), a group of rare clonal hematologic disorders characterized by dysplastic hematopoiesis and high mortality, remains unclear. We performed AML and MDS genome-wide association studies (GWAS) in the DISCOVeRY-BMT cohorts (2,309 cases and 2,814 controls). Association analysis based on subsets (ASSET) was used to conduct a summary statistics SNP-based analysis of MDS and AML subtypes. For each AML and MDS case and control we used PrediXcan to estimate the component of gene expression determined by their genetic profile and correlate this imputed gene expression level with risk of developing disease in a transcriptome-wide association study (TWAS). ASSET identified an increased risk for de novo AML and MDS (OR = 1.38, 95% CI, 1.26-1.51, Pmeta = 2.8 × 10-12) in patients carrying the T allele at s12203592 in Interferon Regulatory Factor 4 (IRF4), a transcription factor which regulates myeloid and lymphoid hematopoietic differentiation. Our TWAS analyses showed increased IRF4 gene expression is associated with increased risk of de novo AML and MDS (OR = 3.90, 95% CI, 2.36-6.44, Pmeta = 1.0 × 10-7). The identification of IRF4 by both GWAS and TWAS contributes valuable insight on the role of genetic variation in AML and MDS susceptibility.

Abstract PR05: Epigenetic disruption of vitamin D receptor signaling in African American prostate cancer alters circadian signaling networks

The current study aimed to define the genomic functions of the vitamin D receptor (VDR) in African American (AA) prostate cancer (PCa) compared to European American (EA) counterparts. VDR-dependent ChIP-Seq and RNA-Seq gene was undertaken in EA (non-malignant HPr1AR and malignant LNCaP) and AA (non-malignant RC43N and malignant RC43T) prostate models, combined with analyses of three PCa cohorts. In AA prostate models the VDR is highly expressed, binds more frequently, and is enriched in active and poised enhancers. Motif analyses revealed selective enrichment, including ZBTB33/KAISO in AA cells and ERG family members in EA cells and, similarly, GIGGLE analyses revealed AA VDR cistromes were significantly overlapped with core circadian rhythm transcription factors (e.g. NONO). Combining VDR-dependent ChIP-Seq and RNA-Seq established that AA cells displayed a significantly stronger transcriptional response, compared to EA cells, and was most responsive in non-malignant RC43N. For example, RC43N transcriptional responses were enriched for circadian rhythm (NES 2.7) and inflammation, whereas in RC43T the same gene networks were repressed. To reveal how VDR/1,25(OH)2D3 signaling is corrupted in AA PCa, we mined TCGA data and revealed that the BAZ1A/SMARCA5 chromatin remodeling complex was uniquely altered in TMPRSS2:ERG fusion negative AA PCa. We are currently examining the impact of BAZ1A on the 1,25(OH)2D3 responsiveness. We also identified miRNA associated with progression from HGPIN to PCa in AA men, and that ~30% were bound by VDR and regulated by 1,25(OH)2D3, although ~5% of EA progression miRNA were VDR-responsive. For example, VDR binds to miR-199b, is uniquely 1,25(OH)2D3 up-regulated in RC43N but repressed in RC43T, and associates with AA progression from HGPIN to PCa. MiR-199b regulates expression of NPAS2, a core circadian transcription factor. Finally, leveraging a previously analyzed cohort of 1,25(OH)2D3-treated PCa patients revealed that AA tumors were intrinsically more 1,25(OH)2D3-responsive than EA counterparts, reflecting the cell line analyses. 1,25(OH)2D3 regulated circadian transcriptional regulators (e.g. NOCT and MYBBP1A) and inflammatory signals. Together, these data suggest VDR transcriptional control in AA men is more dynamic than in EA men, and is primed to govern inflammatory and circadian rhythm pathways. This is frequently disrupted, including by altered BAZ1A/SMARCA5 expression and/or reduced environmental-regulated serum vitamin D3 levels, and leads to altered regulation of circadian rhythm process, and inflammatory signals. Therefore, the VDR axis lies at the cross-roads of biopsychosocial processes that contributes to PCa health disparities.

Citation Format: Manjunath Siddappa, Sajad D. Wani, Jaimie S. Gray, Mark D. Long, Hedieh Jafari, Hsuchang Wu, Honhe Wang, Rebecca Morgan, Gary Hardiman, James Marshall, Chanita Hughes-Halbert, Lara E. Sucheston-Campbell, Clayton L. Yates, Moray J. Campbell. Epigenetic disruption of vitamin D receptor signaling in African American prostate cancer alters circadian signaling networks [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PR05.

High dimensional model representation of log likelihood ratio: binary classification with SNP data

Background

Developing binary classification rules based on SNP observations has been a major challenge for many modern bioinformatics applications, e.g., predicting risk of future disease events in complex conditions such as cancer. Small-sample, high-dimensional nature of SNP data, weak effect of each SNP on the outcome, and highly non-linear SNP interactions are several key factors complicating the analysis. Additionally, SNPs take a finite number of values which may be best understood as ordinal or categorical variables, but are treated as continuous ones by many algorithms.

Methods

We use the theory of high dimensional model representation (HDMR) to build appropriate low dimensional glass-box models, allowing us to account for the effects of feature interactions. We compute the second order HDMR expansion of the log-likelihood ratio to account for the effects of single SNPs and their pairwise interactions. We propose a regression based approach, called linear approximation for block second order HDMR expansion of categorical observations (LABS-HDMR-CO), to approximate the HDMR coefficients. We show how HDMR can be used to detect pairwise SNP interactions, and propose the fixed pattern test (FPT) to identify statistically significant pairwise interactions.

Results

We apply LABS-HDMR-CO and FPT to synthetically generated HAPGEN2 data as well as to two GWAS cancer datasets. In these examples LABS-HDMR-CO enjoys superior accuracy compared with several algorithms used for SNP classification, while also taking pairwise interactions into account. FPT declares very few significant interactions in the small sample GWAS datasets when bounding false discovery rate (FDR) by 5%, due to the large number of tests performed. On the other hand, LABS-HDMR-CO utilizes a large number of SNP pairs to improve its prediction accuracy. In the larger HAPGEN2 dataset FTP declares a larger portion of SNP pairs used by LABS-HDMR-CO as significant.

Conclusion

LABS-HDMR-CO and FPT are interesting methods to design prediction rules and detect pairwise feature interactions for SNP data. Reliably detecting pairwise SNP interactions and taking advantage of potential interactions to improve prediction accuracy are two different objectives addressed by these methods. While the large number of potential SNP interactions may result in low power of detection, potentially interacting SNP pairs, of which many might be false alarms, can still be used to improve prediction accuracy.

Abstract 4613: Cross-ancestry genome-wide association study identifies six new loci for breast cancer in women of African and european ancestry

Background: Over 180 genetic variants have been identified as risk loci for breast cancer. However, most loci were discovered using European ancestry populations. As some common susceptibility loci are shared across populations, we aim to discover new risk loci for breast cancer using a cross-ancestry genome-wide association study (GWAS) approach.

Methods: Data from five GWAS studies in women of African ancestry with a combined sample size of 9241 cases and 10192 controls were used to generate pooled breast cancer risk estimates in a fixed effect meta-analysis, and this served as the discovery dataset. Summary statistics from the GWAS conducted in European ancestry populations (Breast Cancer Association Consortium, 122977 cases and 105974 controls) served as the validation dataset. The variants that were associated with breast cancer risk at P &lt; 0.01 in the GWAS of African ancestry were meta-analyzed with the GWAS in European ancestry. A locus was considered novel if the lead index variant was genome-wide significant (5 × 10−8) in the cross-ancestry meta-analysis and &gt;500kb away from known breast cancer risk loci. Conditional on the lead index variants, we searched for additional signals in each locus using multivariable logistic regression. Analyses were done separately for ER-positive, ER-negative and overall breast cancer risk.

Results: We discovered four novel loci for overall breast cancer risk (1p13.3, 5q31.1, 15q24, and 15q26.3) and two novel loci for ER-negative breast cancer (1q41 and 7q11.23) at the genome-wide significance level of P &lt; 5 × 10−8. Three index single nucleotide polymorphism (SNPs) lie within introns of genes (KCNK2, C5orf56, and SIN3A) and the other index SNPs are located in intergenic regions (close to GSTM4 and AMPD2, CASTOR2, and the antisense DNA RP11-168G16.2). The direction of the associations was consistent between the GWASs of African and European descendants. At the 15q24 locus, we found an additional SNP (in the intron of the SCAMP2 gene) to be independently associated with overall breast cancer risk.

Conclusions: We have identified six new risk loci that may contribute to better prediction of breast cancer risk in African ancestry populations and provide new insights into mechanisms of breast cancer carcinogenesis. Replication of these loci in multiple populations and functional studies can help to identify causal variants.

Citation Format: Babatunde Adedokun, Zhaohui Du, Guimin Gao, Thomas Ahearn, Kathryn L. Lunetta, Gary Zirpoli, Jonine Figueroa, Esther M. John, Leslie Bernstein, Wei Zheng, Jennifer J. Hu, Regina G. Ziegler, Sarah Nyante, Elisa V. Bandera, Sue A. Ingles, Michael F. Press, Sandra L. Deming, Jorge L. Rodriguez-Gil, Song Yao, Temidayo O. Ogundiran, Oladosu Ojengbede, William Blot, Melissa Troester, Katherine L. Nathanson, Anselm Hennis, Barbara Nemesure, Stefan Ambs, Lara E. Sucheston-Campbell, Jeannette T. Bensen, Stephen J. Chanock, Andrew F. Olshan, Christine B. Ambrosone, David V. Conti, Olufunmilayo I. Olopade, Montserrat Garcia-Closas, Julie R. Palmer, Christopher A. Haiman, Dezheng Huo. Cross-ancestry genome-wide association study identifies six new loci for breast cancer in women of African and european ancestry [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4613.

Abstract 2320: Evaluating a polygenic risk score for breast cancer in women of African ancestry

Background: A polygenic risk score (PRS) for breast cancer including 313 common variants developed by the Breast Cancer Association Consortium (BCAC) has been demonstrated to identify women who are at high risk of developing breast cancer [odds ratio (OR 95%CI) = 1.61 (1.57-1.65) per SD] in women of European ancestry. In the present study, we examined the performance of the 313-variant PRS and a PRS including 179 variants reaching genome-wide significance in previous genome-wide association studies (GWAS), in women of African ancestry.

Methods: We assembled genotype data for women of African ancestry from 28 breast cancer studies, including a total of 9,241 cases and 10,193 controls. We constructed the 179-variant and 313-variant PRSs with relative risk weights for each variant estimated in women of European ancestry in BCAC. The associations between the two PRSs and overall, ER+ and ER- breast cancer risk were estimated using logistic regression adjusting for age, study site and principal components. Discriminatory accuracy of the PRSs was evaluated using the receiver operating characteristic curve (AUROC). We then recalibrated the 179-variant PRS by replacing index variants with variants in each region that better captured risk in women of African ancestry and used relative risk weights estimated in women of African ancestry. We also assessed PRS performance by age (&lt;55 versus ≥ 55 years).

Results: Both the 179 and 313- variant PRSs were significantly associated with overall, ER+ and ER- breast cancer risk, with odds ratios (OR) per standard deviation of 1.21~1.37 and AUROCs ranging from 0.57 to 0.59. The 179-variant PRS outperformed in ER- cancer [1.31(1.24,1.37) per SD] while the 313-SNP PRS was better for overall [1.27(1.23,1.31) per SD] and ER+ cancer [1.37(1.32,1.43) per SD]. For overall breast cancer, compared to women with average risk (40th-60th PRS percentiles), women in the top decile of PRS had a 1.54 (95% CI: 1.38, 1.72)-fold increased risk. The performance of the recalibrated 179-variant PRS was not improved (average AUROC=0.56). The PRS ORs did not differ significantly across age strata (P-value for age interaction = 0.63).

Conclusion: Our study shows that both 179 and 313 variant PRS stratify breast cancer risk in women of African ancestry, with attenuated performance compared to that reported in European and in Latina populations. Future work is needed to improve breast cancer risk stratification for women of African ancestry.

Citation Format: Zhaohui Du, Guimin Gao, Babatunde Adedokun, Thomas Ahearn, Kathryn L. Lunetta, Gary Zirpoli, Melissa Troester, Edward A. Ruiz-Narváez, Stephen Haddad, Jonine Figueroa, Esther M. John, Leslie Bernstein, Wei Zheng, Jennifer J. Hu, Regina G. Ziegler, Sarah Nyante, Elisa V. Bandera, Sue A. Ingles, Michael F. Press, Sandra L. Deming, Jorge L. Rodriguez-Gil, Song Yao, Temidayo O. Ogundiran, Oladosu A. Ojengbede, William Blot, Katherine L. Nathanson, Anselm Hennis, Barbara Nemesure, Stefan Ambs, Lara E. Sucheston-Campbell, Jeannette T. Bensen, Stephen J. Chanock, Andrew F. Olshan, Christine B. Ambrosone, David V. Conti, Olufunmilayo I. Olopade, Julie R. Palmer, Montserrat Garcia-Closas, Dezheng Huo, Christopher A. Haiman. Evaluating a polygenic risk score for breast cancer in women of African ancestry [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2320.

Dietary Supplement Use During Chemotherapy and Survival Outcomes of Patients With Breast Cancer Enrolled in a Cooperative Group Clinical Trial (SWOG S0221)

PURPOSE

Despite reported widespread use of dietary supplements during cancer treatment, few empirical data with regard to their safety or efficacy exist. Because of concerns that some supplements, particularly antioxidants, could reduce the cytotoxicity of chemotherapy, we conducted a prospective study ancillary to a therapeutic trial to evaluate associations between supplement use and breast cancer outcomes.

METHODS

Patients with breast cancer randomly assigned to an intergroup metronomic trial of cyclophosphamide, doxorubicin, and paclitaxel were queried on their use of supplements at registration and during treatment (n =1,134). Cox proportional hazards regression adjusting for clinical and lifestyle variables was used. Recurrence and survival were indexed at 6 months after enrollment using a landmark approach.

RESULTS

There were indications that use of any antioxidant supplement (vitamins A, C, and E; carotenoids; coenzyme Q10) both before and during treatment was associated with an increased hazard of recurrence (adjusted hazard ratio [adjHR], 1.41; 95% CI, 0.98 to 2.04; P = .06) and, to a lesser extent, death (adjHR, 1.40; 95% CI, 0.90 to 2.18; P = .14). Relationships with individual antioxidants were weaker perhaps because of small numbers. For nonantioxidants, vitamin B12 use both before and during chemotherapy was significantly associated with poorer disease-free survival (adjHR, 1.83; 95% CI, 1.15 to 2.92; P < .01) and overall survival (adjHR, 2.04; 95% CI, 1.22 to 3.40; P < .01). Use of iron during chemotherapy was significantly associated with recurrence (adjHR, 1.79; 95% CI, 1.20 to 2.67; P < .01) as was use both before and during treatment (adjHR, 1.91; 95% CI, 0.98 to 3.70; P = .06). Results were similar for overall survival. Multivitamin use was not associated with survival outcomes.

CONCLUSION

Associations between survival outcomes and use of antioxidant and other dietary supplements both before and during chemotherapy are consistent with recommendations for caution among patients when considering the use of supplements, other than a multivitamin, during chemotherapy.

Supplement Use and Chemotherapy-Induced Peripheral Neuropathy in a Cooperative Group Trial (S0221): The DELCaP Study

Background

Chemotherapy-induced peripheral neuropathy (CIPN) can interfere with daily function and quality of life, and there are no known preventive approaches. In a cohort of breast cancer patients receiving paclitaxel as part of a clinical trial (SWOG 0221), we examined the use of dietary supplements both before diagnosis and during treatment in relation to CIPN.

Methods

At registration to S0221, 1225 breast cancer patients completed questionnaires regarding the use of multivitamins and supplements before and at diagnosis. A second questionnaire at six months queried use during treatment. Supplement use was evaluated in relation to CIPN, assessed via the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE v. 3.0) and the self-reported Functional Assessment of Cancer Therapy/Gynecologic Oncology Group Neurotoxicity (FACT/GOG-Ntx) subscale. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed with logistic regression for the CTCAE analyses and ordinal regression for the FACT/GOG-Ntx analyses.

Results

Multivitamin use before diagnosis was associated with reduced symptoms of CIPN (CTCAE-adjusted OR = 0.60, 95% CI = 0.42 to 0.87; FACT/GOG-Ntx-adjusted OR = 0.78, 95% CI = 0.61 to 1.00). Use during treatment was marginally inversely associated with CIPN (CTCAE-adjusted OR = 0.73, 95% CI = 0.49 to 1.08; FACT/GOG-Ntx-adjusted OR = 0.77, 95% CI = 0.60 to 0.99). Other supplement use, either before diagnosis or during treatment, was not statistically significantly associated with CIPN.

Conclusions

Multivitamin use may be associated with reduced risk of CIPN, although individual dietary supplement use did not appreciably affect risk. Multivitamin use could be a surrogate for other related behaviors that are the actual drivers of the association with reduced CIPN. Without prospective randomized trials of vitamin supplementation, recommendations for use or changes to clinical practice are clearly not warranted.

The miR-96 and RARγ signaling axis governs androgen signaling and prostate cancer progression

Expression levels of retinoic acid receptor gamma (NR1B3/RARG, encodes RARγ) are commonly reduced in prostate cancer (PCa). Therefore, we sought to establish the cellular and gene regulatory consequences of reduced RARγ expression, and determine RARγ regulatory mechanisms. RARG shRNA approaches in non-malignant (RWPE-1 and HPr1-AR) and malignant (LNCaP) prostate models revealed that reducing RARγ levels, rather than adding exogenous retinoid ligand, had the greatest impact on prostate cell viability and gene expression. ChIP-Seq defined the RARγ cistrome, which was significantly enriched at active enhancers associated with AR binding sites. Reflecting a significant genomic role for RARγ to regulate androgen signaling, RARγ knockdown in HPr1-AR cells significantly regulated the magnitude of the AR transcriptome. RARγ downregulation was explained by increased miR-96 in PCa cell and mouse models, and TCGA PCa cohorts. Biochemical approaches confirmed that miR-96 directly regulated RARγ expression and function. Capture of the miR-96 targetome by biotin-miR-96 identified that RARγ and a number of RARγ interacting co-factors including TACC1 were all targeted by miR-96, and expression of these genes were prominently altered, positively and negatively, in the TCGA-PRAD cohort. Differential gene expression analyses between tumors in the TCGA-PRAD cohort with lower quartile expression levels of RARG and TACC1 and upper quartile miR-96, compared to the reverse, identified a gene network including several RARγ target genes (e.g., SOX15) that significantly associated with worse disease-free survival (hazard ratio 2.23, 95% CI 1.58 to 2.88, p = 0.015). In summary, miR-96 targets a RARγ network to govern AR signaling, PCa progression and disease outcome.

Associations between self-reported diet during treatment and chemotherapy-induced peripheral neuropathy in a cooperative group trial (S0221)

Background

The pathophysiology of chemotherapy-induced peripheral neuropathy (CIPN) is not well understood. Currently, dose reduction is the only recommendation for alleviating symptoms, often leading to premature treatment cessation. The primary aim of this analysis was to determine the association between components of diet during taxane treatment for breast cancer and change in CIPN symptoms over treatment.

Methods

Women with stage II or III invasive breast cancer were enrolled into an ancillary study to the North American Breast Cancer Intergroup phase III trial (S0221) led by the Southwest Oncology Group (SWOG). Questionnaires including a food frequency questionnaire and the Functional Assessment of Cancer Treatment Gynecologic Oncology Group—Neurotoxicity were administered to assess diet and neuropathic conditions at baseline and during chemotherapy. Ordinal regression was used to estimate odds ratios (ORs) for associations between various food groups and change in neuropathy score (< 10%, 10–30%, > 30%) (n = 900).

Results

The odds of worse neuropathy decreased by 21% for each increase in tertile of grain consumption (OR = 0.79, 95% CI 0.66–0.94, p = 0.009). We also observed a nominal 19% increase with higher consumption of citrus fruits (OR = 1.19, 95% CI 1.01–1.40, p = 0.05).

Conclusions

Distinguishing between those who experienced a moderate and a severe change in neuropathy, we found that citrus fruit and grain consumption may play a role in the severity of symptoms. Since there are no existing dietary recommendations for the management of CIPN, further research is needed to investigate whether there may be certain foods that could worsen or alleviate neuropathy symptoms associated with treatment for breast cancer.

Trial registration

ClinicalTrials.gov, NCT03413761. Registered retrospectively on 29 January 2018.

gwasurvivr: an R package for genome-wide survival analysis

SUMMARY

To address the limited software options for performing survival analyses with millions of SNPs, we developed gwasurvivr, an R/Bioconductor package with a simple interface for conducting genome-wide survival analyses using VCF (outputted from Michigan or Sanger imputation servers), IMPUTE2 or PLINK files. To decrease the number of iterations needed for convergence when optimizing the parameter estimates in the Cox model, we modified the R package survival; covariates in the model are first fit without the SNP, and those parameter estimates are used as initial points. We benchmarked gwasurvivr with other software capable of conducting genome-wide survival analysis (genipe, SurvivalGWAS_SV and GWASTools). gwasurvivr is significantly faster and shows better scalability as sample size, number of SNPs and number of covariates increases.

AVAILABILITY AND IMPLEMENTATION

gwasurvivr, including source code, documentation and vignette are available at: http://bioconductor.org/packages/gwasurvivr.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Abstract B016: MicroRNA drivers of TMPRSS2 fusion-negative prostate cancer in African Americans

TMPRSS2:ERG fusions are being pursued as genomic biomarkers to define disease state and predict treatment responses in prostate cancer (PCa). Successful biomarker exploitation depends on the frequency of TMPRSS2 fusions, which are very common in European American (EA) men with both high-grade PIN, and in at least 50% PCa patients. However, the incidence is far lower in men from other ethnicities, and as low as 10% among African American (AA) patients. Therefore in AA patients, TMPRSS2:ERG fusion events are unlikely to either explain the elevated incidence of PCa or be relevant as a biomarker.

To seek novel biomarkers of TMPRSS2 fusion-negative PCa we have considered a role for miRNA drivers. Previously, we analyzed miRNA expression in various PCa cohorts, to identify differentially expressed miRNA in TMPRSS2 fusion-negative disease in AA men. These cohorts included PCa in AA men, PCa progression in EA men following surgery, and mining of TCGA-PRAD and MSKCC cohorts to identify TMPRSS2 fusion-negative associated miRNA.

We have now complemented this by a genome-wide miRNA screen in serum samples using the NanoString platform of 97 aged matched EA and AA men with HGPIN, ~30% of whom progressed to PCa (SWOG S9917). Serum levels of 22 miRNA significantly distinguished AA men who progressed to PCa, from those whose HGPIN remained stable; these miRNA included miR-25-3p, miR-93-5p, and miR-423-5p.

Combining the findings identified 38 miRNA, and we sought to identify shared and unique links between these miRNA associated with PCa progression and TMPRSS2 fusion-negative status. Although the PCa drivers in AA men remain obscured, strong links are emerging between vitamin D receptor (VDR) signaling and AA PCa. Epidemiologic studies have established links between low serum vitamin D3 levels and PCa incidence and progression in AA men. VDR signaling has also been linked to altered local immune responses in AA PCa patients. Remarkably, we found strong evidence from our studies and those of others that 29 of the 38 miRNA identified were regulated by 1,25(OH)2D3 in prostate cells, including the miR-25-miR-93-miR-106b cluster, miR-152 and miR-423-5p.

As this regulation includes both direct and indirect effects, we examined how these miRNA genes, or host genes, were targeted by the vitamin D receptor (VDR). Previously, we identified VDR binding at the MCM7 host gene for the miR-25-miR-93-miR-106b cluster used ChIP-PCR in nonmalignant RWPE-1 cells. We have now mined publicly available VDR ChIP-Seq in LNCaP cells (GSE64656); these cells are TMPRSS2 fusion negative. Selecting all binding sites within +/- 7.5 kb of a TSS, we identified VDR associated with 8/29 miRNA, including NSRP1 (miR-423-5p host gene) and COPZ2 (miR-152 host gene).

To measure associations with TMPRSS2 fusion-negative PCa, we identified the most commonly altered of the 38 miRNA in the TCGA-PRAD cohort. Specifically, we identified 18 miRNA altered by more than 2 Z scores in more than 25% tumors, which included miR-25-3p, miR-93-5p, miR-152, and miR-423-5p. Expression of these miRNA clustered tumors into two groups that significantly distinguished TMPRSS2 fusion status (p=0.007) and race (p=0.01). 15/18 miRNA were known to be regulated by 1,25(OH)2D3, and 5/8 were bound by VDR in LNCaP cells. Currently, we are measuring how these 18 miRNA are regulated by 1,25(OH)2D3 in AA and EA nonmalignant and malignant prostate cell models: AA-RC77T, RC43T; EA-HPr-1AR, LNCaP, VCaP (TMPRSS2 fusion positive), PC-3.

Together these data suggest that a distinct PCa subtype, independent of TMPRSS2 fusion, arises more frequently in AA men due to reduced 1,25(OH)2D3 levels that disrupts VDR regulation of miRNA, including miR-25-3p, miR-93, miR-152, and miR-423-5p. Understanding the miRNA regulated gene networks has the potential to illuminate the cancer drivers in TMPRSS2 fusion-negative AA PCa, and expression of these miRNA may predict progression risks.

Citation Format: Manjunath Siddappa, Jason White, Honghe Wang, Lara E. Sucheston-Campbell, Clayton Yates, Moray J. Campbell. MicroRNA drivers of TMPRSS2 fusion-negative prostate cancer in African Americans [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr B016.

Genetic ancestry and population differences in levels of inflammatory cytokines in women: Role for evolutionary selection and environmental factors

Selection pressure due to exposure to infectious pathogens endemic to Africa may explain distinct genetic variations in immune response genes. However, the impact of those genetic variations on human immunity remains understudied, especially within the context of modern lifestyles and living environments, which are drastically different from early humans in sub Saharan Africa. There are few data on population differences in constitutional immune environment, where genetic ancestry and environment are likely two primary sources of variation. In a study integrating genetic, molecular and epidemiologic data, we examined population differences in plasma levels of 14 cytokines involved in innate and adaptive immunity, including those implicated in chronic inflammation, and possible contributing factors to such differences, in 914 AA and 855 EA women. We observed significant differences in 7 cytokines, including higher plasma levels of CCL2, CCL11, IL4 and IL10 in EAs and higher levels of IL1RA and IFNα2 in AAs. Analyses of a wide range of demographic and lifestyle factors showed significant impact, with age, education level, obesity, smoking, and alcohol intake, accounting for some, but not all, observed population differences for the cytokines examined. Levels of two pro-inflammatory chemokines, CCL2 and CCL11, were strongly associated with percent of African ancestry among AAs. Through admixture mapping, the signal was pinpointed to local ancestry at 1q23, with fine-mapping analysis refined to the Duffy-null allele of rs2814778. In AA women, this variant was a major determinant of systemic levels of CCL2 (p = 1.1e-58) and CCL11 (p = 2.2e-110), accounting for 19% and 40% of the phenotypic variance, respectively. Our data reveal strong ancestral footprints in inflammatory chemokine regulation. The Duffy-null allele may indicate a loss of the buffering function for chemokine levels. The substantial immune differences by ancestry may have broad implications to health disparities between AA and EA populations.

A survey of microRNA single nucleotide polymorphisms identifies novel breast cancer susceptibility loci in a case-control, population-based study of African-American women

BACKGROUND

MicroRNAs (miRNAs) regulate gene expression and influence cancer. Primary transcripts of miRNAs (pri-miRNAs) are poorly annotated and little is known about the role of germline variation in miRNA genes and breast cancer (BC). We sought to identify germline miRNA variants associated with BC risk and tumor subtype among African-American (AA) women.

METHODS

Under the African American Breast Cancer Epidemiology and Risk (AMBER) Consortium, genotyping and imputed data from four studies on BC in AA women were combined into a final dataset containing 224,188 miRNA gene single nucleotide polymorphisms (SNPs) for 8350 women: 3663 cases and 4687 controls. The primary miRNA sequence was identified for 566 miRNA genes expressed in Encyclopedia of DNA Elements (ENCODE) Tier 1 cell types and human pancreatic islets. Association analysis was conducted using logistic regression for BC status overall and by tumor subtype.

RESULTS

A novel BC signal was localized to an 8.6-kb region of 17q25.3 by four SNPs (rs9913477, rs1428882938, rs28585511, and rs7502931) and remained statistically significant after multiple test correction (odds ratio (OR) = 1.44, 95% confidence interval (CI) = 1.26-1.65; p = 3.15 × 10-7; false discovery rate (FDR) = 0.03). These SNPs reside in a genomic location that includes both the predicted primary transcript of the noncoding miRNA gene MIR3065 and the first intron of the gene for brain-specific angiogenesis inhibitor 1-associated protein 2 (BAIAP2). Furthermore, miRNA-associated SNPs on chromosomes 1p32.3, 5q32, and 3p25.1 were the strongest signals for hormone receptor, luminal versus basal-like, and HER2 enrichment status, respectively. A second phase of genotyping (1397 BC cases, 2418 controls) that included two SNPs in the 8.6-kb region was used for validation and meta-analysis. While neither rs4969239 nor rs9913477 was validated, when meta-analyzed with the original dataset their association with BC remained directionally consistent (OR = 1.29, 95% CI = 1.16-1.44 (p = 4.18 × 10-6) and OR = 1.33, 95% CI = 1.17-1.51 (p = 1.6 × 10-5), respectively).

CONCLUSION

Germline genetic variation indicates that MIR3065 may play an important role in BC development and heterogeneity among AA women. Further investigation to determine the potential functional effects of these SNPs is warranted. This study contributes to our understanding of BC risk in AA women and highlights the complexity in evaluating variation in gene-dense regions of the human genome.

Exome chip analyses identify genes affecting mortality after HLA-matched unrelated-donor blood and marrow transplantation

Although survival outcomes have significantly improved, up to 40% of patients die within 1 year of HLA-matched unrelated-donor blood and marrow transplantation (BMT). To identify non-HLA genetic contributors to mortality after BMT, we performed the first exome-wide association study in the DISCOVeRY-BMT cohorts using the Illumina HumanExome BeadChip. This study includes 2473 patients with acute myeloid leukemia, acute lymphoblastic leukemia, or myelodysplastic syndrome and 2221 10/10 HLA-matched donors treated from 2000 to 2011. Single-variant and gene-level analyses were performed on overall survival (OS), transplantation-related mortality (TRM), and disease-related mortality (DRM). Genotype mismatches between recipients and donors in a rare nonsynonymous variant of testis-expressed gene TEX38 significantly increased risk of TRM, which was more dramatic when either the recipient or donor was female. Using the SKAT-O test to evaluate gene-level effects, variant genotypes of OR51D1 in recipients were significantly associated with OS and TRM. In donors, 4 (ALPP, EMID1, SLC44A5, LRP1), 1 (HHAT), and 2 genes (LYZL4, NT5E) were significantly associated with OS, TRM, and DRM, respectively. Inspection of NT5E crystal structures showed 4 of the associated variants affected the enzyme structure and likely decreased the catalytic efficiency of the enzyme. Further confirmation of these findings and additional functional studies may provide individualized risk prediction and prognosis, as well as alternative donor selection strategies.

Genetic Variants in Immune-Related Pathways and Breast Cancer Risk in African American Women in the AMBER Consortium

Background: Constitutional immunity shaped by exposure to endemic infectious diseases and parasitic worms in Sub-Saharan Africa may play a role in the etiology of breast cancer among African American (AA) women.Methods: A total of 149,514 gene variants in 433 genes across 45 immune pathways were analyzed in the AMBER consortium among 3,663 breast cancer cases and 4,687 controls. Gene-based pathway analyses were conducted using the adaptive rank truncated product statistic for overall breast cancer risk, and risk by estrogen receptor (ER) status. Unconditional logistic regression analysis was used to estimate ORs and 95% confidence intervals (CIs) for single variants.Results: The top pathways were Interleukin binding (P = 0.01), Biocarta TNFR2 (P = 0.005), and positive regulation of cytokine production (P = 0.024) for overall, ER+, and ER- cancers, respectively. The most significant gene was IL2RB (P = 0.001) for overall cancer, with rs228952 being the top variant identified (OR = 0.85; 95% CI, 0.79-0.92). Only BCL3 contained a significant variant for ER+ breast cancer. Variants in IL2RB, TLR6, IL8, PRKDC, and MAP3K1 were associated with ER- disease. The only genes showing heterogeneity between ER- and ER+ cancers were TRAF1, MAP3K1, and MAPK3 (P ≤ 0.02). We also noted genes associated with autoimmune and atopic disorders.Conclusions: Findings from this study suggest that genetic variants in immune pathways are relevant to breast cancer susceptibility among AA women, both for ER+ and ER- breast cancers.Impact: Results from this study extend our understanding of how inherited genetic variation in immune pathways is relevant to breast cancer susceptibility. Cancer Epidemiol Biomarkers Prev; 27(3); 321-30. ©2018 AACR.

Genome-wide association studies in women of African ancestry identified 3q26.21 as a novel susceptibility locus for oestrogen receptor negative breast cancer

Multiple breast cancer loci have been identified in previous genome-wide association studies, but they were mainly conducted in populations of European ancestry. Women of African ancestry are more likely to have young-onset and oestrogen receptor (ER) negative breast cancer for reasons that are unknown and understudied. To identify genetic risk factors for breast cancer in women of African descent, we conducted a meta-analysis of two genome-wide association studies of breast cancer; one study consists of 1,657 cases and 2,029 controls genotyped with Illumina’s HumanOmni2.5 BeadChip and the other study included 3,016 cases and 2,745 controls genotyped using Illumina Human1M-Duo BeadChip. The top 18,376 single nucleotide polymorphisms (SNP) from the meta-analysis were replicated in the third study that consists of 1,984 African Americans cases and 2,939 controls. We found that SNP rs13074711, 26.5 Kb upstream of TNFSF10 at 3q26.21, was significantly associated with risk of oestrogen receptor (ER)-negative breast cancer (odds ratio [OR]=1.29, 95% CI: 1.18-1.40; P = 1.8 × 10 − 8). Functional annotations suggest that the TNFSF10 gene may be involved in breast cancer aetiology, but further functional experiments are needed. In addition, we confirmed SNP rs10069690 was the best indicator for ER-negative breast cancer at 5p15.33 (OR = 1.30; P = 2.4 × 10 − 10) and identified rs12998806 as the best indicator for ER-positive breast cancer at 2q35 (OR = 1.34; P = 2.2 × 10 − 8) for women of African ancestry. These findings demonstrated additional susceptibility alleles for breast cancer can be revealed in diverse populations and have important public health implications in building race/ethnicity-specific risk prediction model for breast cancer.

OATP1B2 deficiency protects against paclitaxel-induced neurotoxicity

Paclitaxel is among the most widely used anticancer drugs and is known to cause a dose-limiting peripheral neurotoxicity, the initiating mechanisms of which remain unknown. Here, we identified the murine solute carrier organic anion-transporting polypeptide B2 (OATP1B2) as a mediator of paclitaxel-induced neurotoxicity. Additionally, using established tests to assess acute and chronic paclitaxel-induced neurotoxicity, we found that genetic or pharmacologic knockout of OATP1B2 protected mice from mechanically induced allodynia, thermal hyperalgesia, and changes in digital maximal action potential amplitudes. The function of this transport system was inhibited by the tyrosine kinase inhibitor nilotinib through a noncompetitive mechanism, without compromising the anticancer properties of paclitaxel. Collectively, our findings reveal a pathway that explains the fundamental basis of paclitaxel-induced neurotoxicity, with potential implications for its therapeutic management.

A methodological study of genome-wide DNA methylation analyses using matched archival formalin-fixed paraffin embedded and fresh frozen breast tumors

Background

DNA from archival formalin-fixed and paraffin embedded (FFPE) tissue is an invaluable resource for genome-wide methylation studies although concerns about poor quality may limit its use. In this study, we compared DNA methylation profiles of breast tumors using DNA from fresh-frozen (FF) tissues and three types of matched FFPE samples.

Results

For 9/10 patients, correlation and unsupervised clustering analysis revealed that the FF and FFPE samples were consistently correlated with each other and clustered into distinct subgroups. Greater than 84% of the top 100 loci previously shown to differentiate ER+ and ER– tumors in FF tissues were also FFPE DML. Weighted Correlation Gene Network Analyses (WCGNA) grouped the DML loci into 16 modules in FF tissue, with ~85% of the module membership preserved across tissue types.

Materials and Methods

Restored FFPE and matched FF samples were profiled using the Illumina Infinium HumanMethylation450K platform. Methylation levels (β-values) across all loci and the top 100 loci previously shown to differentiate tumors by estrogen receptor status (ER+ or ER−) in a larger FF study, were compared between matched FF and FFPE samples using Pearson's correlation, hierarchical clustering and WCGNA. Positive predictive values and sensitivity levels for detecting differentially methylated loci (DML) in FF samples were calculated in an independent FFPE cohort.

Conclusions

FFPE breast tumors samples show lower overall detection of DMLs versus FF, however FFPE and FF DMLs compare favorably. These results support the emerging consensus that the 450K platform can be employed to investigate epigenetics in large sets of archival FFPE tissues.

Gene-Hormone Therapy Interaction and Fracture Risk in Postmenopausal Women

CONTEXT

Evidence supports a protective effect of menopausal hormone therapy (HT) on bone. However, whether genetic susceptibility modifies the association of HT and fracture risk is not sufficiently explored.

OBJECTIVE

The objective was to test an interaction between genetic susceptibility and HT on fracture risk.

DESIGN

We constructed two weighted genetic risk scores (GRSs) based on 16 fracture-associated variants (Fx-GRSs) and 50 bone mineral density variants (BMD-GRSs). We used Cox regression to estimate the main effects of GRSs and their interactions with HT on fracture risk. We estimated the relative excess risk due to interaction (RERI) as a measure of additive interaction. We also used the case-only approach to test for a multiplicative interaction.

SETTING

Forty US clinical centers.

PARTICIPANTS

A total of 9922 genotyped white postmenopausal women (age, 50 to 79) from the Women's Health Initiative HT randomized trials.

MAIN OUTCOME MEASURES

Adjudicated fracture incidence.

RESULTS

Both GRSs were associated with fracture risk per 1-unit increment in GRS (hazard ratio, 1.04 [95% confidence interval, 1.02 to 1.06] for Fx-GRS and hazard ratio, 1.03 [95% confidence interval,1.02-1.04] for BMD-GRS). We found no evidence for multiplicative interaction for either of the GRS. However, we observed a substantial additive interaction, where the highest quartile of both GRSs and randomization to placebo have excess fracture risk: Fx-GRS P for RERI = 0.047, BMD-GRS P for RERI = 0.046.

CONCLUSIONS

These results suggest that HT reduces fracture risk in postmenopausal women, especially in those at highest genetic risk of fracture and low BMD.

Identification of 12 new susceptibility loci for different histotypes of epithelial ovarian cancer

To identify common alleles associated with different histotypes of epithelial ovarian cancer (EOC), we pooled data from multiple genome-wide genotyping projects totaling 25,509 EOC cases and 40,941 controls. We identified nine new susceptibility loci for different EOC histotypes: six for serous EOC histotypes (3q28, 4q32.3, 8q21.11, 10q24.33, 18q11.2 and 22q12.1), two for mucinous EOC (3q22.3 and 9q31.1) and one for endometrioid EOC (5q12.3). We then performed meta-analysis on the results for high-grade serous ovarian cancer with the results from analysis of 31,448 BRCA1 and BRCA2 mutation carriers, including 3,887 mutation carriers with EOC. This identified three additional susceptibility loci at 2q13, 8q24.1 and 12q24.31. Integrated analyses of genes and regulatory biofeatures at each locus predicted candidate susceptibility genes, including OBFC1, a new candidate susceptibility gene for low-grade and borderline serous EOC.

Characterizing Genetic Susceptibility to Breast Cancer in Women of African Ancestry

Background: Genome-wide association studies have identified approximately 100 common genetic variants associated with breast cancer risk, the majority of which were discovered in women of European ancestry. Because of different patterns of linkage disequilibrium, many of these genetic markers may not represent signals in populations of African ancestry.Methods: We tested 74 breast cancer risk variants and conducted fine-mapping of these susceptibility regions in 6,522 breast cancer cases and 7,643 controls of African ancestry from three genetic consortia (AABC, AMBER, and ROOT).Results: Fifty-four of the 74 variants (73%) were found to have ORs that were directionally consistent with those previously reported, of which 12 were nominally statistically significant (P < 0.05). Through fine-mapping, in six regions (3p24, 12p11, 14q13, 16q12/FTO, 16q23, 19p13), we observed seven markers that better represent the underlying risk variant for overall breast cancer or breast cancer subtypes, whereas in another two regions (11q13, 16q12/TOX3), we identified suggestive evidence of signals that are independent of the reported index variant. Overlapping chromatin features and regulatory elements suggest that many of the risk alleles lie in regions with biological functionality.Conclusions: Through fine-mapping of known susceptibility regions, we have revealed alleles that better characterize breast cancer risk in women of African ancestry.Impact: The risk alleles identified represent genetic markers for modeling and stratifying breast cancer risk in women of African ancestry. Cancer Epidemiol Biomarkers Prev; 26(7); 1016-26. ©2017 AACR.

The influence of genetic susceptibility and calcium plus vitamin D supplementation on fracture risk

Background: Fracture is a complex trait, affected by both genetic and environmental factors. A meta-analysis of genome-wide association studies (GWASs) identified multiple bone mineral density (BMD) and fracture-associated loci.Objective: We conducted a study to evaluate whether fracture genetic risk score (Fx-GRS) and bone mineral density genetic risk score (BMD-GRS) modify the association between the intake of calcium with vitamin D (CaD) and fracture risk.Design: Data from 5823 white postmenopausal women from the Women's Health Initiative CaD randomized trial were included. Participants received 1000 mg elemental Ca with 400 IU vitamin D3/d or placebo (median follow-up: 6.5 y). Total fracture was defined as first fracture of any type. We computed the Fx-GRS with 16 fracture- and BMD-associated variants, and the BMD-GRS with 50 BMD-associated variants. We used Cox regression and a case-only approach to test for multiplicative interaction. Additive interaction was assessed with the relative excess risk due to interaction (RERI). We analyzed genetic risk score as a continuous variable and a categorical variable based on quartile (quartile 1, quartiles 2-3, and quartile 4).Results: We observed no interaction between the Fx-GRS and CaD on fracture risk; however, we observed a significant multiplicative interaction between the BMD-GRS and CaD assignment (P-interaction = 0.01). In addition, there was a significant negative additive interaction between placebo assignment and higher BMD-GRS: quartiles 2-3, PRERI = 0.03; quartile 4, PRERI = 0.03. In a stratified analysis, the protective effect of CaD on fracture risk was observed in women in the lowest BMD-GRS quartile (HR: 0.60, 95% CI: 0.44, 0.81) but not in women with a higher BMD-GRS.Conclusions: We observed significant effects of CaD intake on fracture risk only in women with the lowest genetic predisposition to low BMD. Future large-scale studies with functional characterization of GWAS findings are warranted to assess the utility of genetic risk score in analysis of risks and benefits of CaD for bone.

No Evidence That Genetic Variation in the Myeloid-Derived Suppressor Cell Pathway Influences Ovarian Cancer Survival

Background: The precise mechanism by which the immune system is adversely affected in cancer patients remains poorly understood, but the accumulation of immunosuppressive/protumorigenic myeloid-derived suppressor cells (MDSCs) is thought to be a prominent mechanism contributing to immunologic tolerance of malignant cells in epithelial ovarian cancer (EOC). To this end, we hypothesized genetic variation in MDSC pathway genes would be associated with survival after EOC diagnoses.Methods: We measured the hazard of death due to EOC within 10 years of diagnosis, overall and by invasive subtype, attributable to SNPs in 24 genes relevant in the MDSC pathway in 10,751 women diagnosed with invasive EOC. Versatile Gene-based Association Study and the admixture likelihood method were used to test gene and pathway associations with survival.Results: We did not identify individual SNPs that were significantly associated with survival after correction for multiple testing (P < 3.5 × 10-5), nor did we identify significant associations between the MDSC pathway overall, or the 24 individual genes and EOC survival.Conclusions: In this well-powered analysis, we observed no evidence that inherited variations in MDSC-associated SNPs, individual genes, or the collective genetic pathway contributed to EOC survival outcomes.Impact: Common inherited variation in genes relevant to MDSCs was not associated with survival in women diagnosed with invasive EOC. Cancer Epidemiol Biomarkers Prev; 26(3); 420-4. ©2016 AACR.

Integration of VDR genome wide binding and GWAS genetic variation data reveals co-occurrence of VDR and NF-κB binding that is linked to immune phenotypes

Background

The nuclear hormone receptor superfamily acts as a genomic sensor of diverse signals. Their actions are often intertwined with other transcription factors. Nuclear hormone receptors are targets for many therapeutic drugs, and include the vitamin D receptor (VDR). VDR signaling is pleotropic, being implicated in calcaemic function, antibacterial actions, growth control, immunomodulation and anti-cancer actions. Specifically, we hypothesized that the biologically significant relationships between the VDR transcriptome and phenotype-associated biology could be discovered by integrating the known VDR transcription factor binding sites and all published trait- and disease-associated SNPs. By integrating VDR genome-wide binding data (ChIP-seq) with the National Human Genome Research Institute (NHGRI) GWAS catalog of SNPs we would see where and which target gene interactions and pathways are impacted by inherited genetic variation in VDR binding sites, indicating which of VDR’s multiple functions are most biologically significant.

Results

To examine how genetic variation impacts VDR function we overlapped 23,409 VDR genomic binding peaks from six VDR ChIP-seq datasets with 191,482 SNPs, derived from GWAS-significant SNPs (Lead SNPs) and their correlated variants (r² > 0.8) from HapMap3 and the 1000 genomes project. In total, 574 SNPs (71 Lead and 503 SNPs in linkage disequilibrium with Lead SNPs) were present at VDR binding loci and associated with 211 phenotypes. For each phenotype a hypergeometric test was used to determine if SNPs were enriched at VDR binding sites. Bonferroni correction for multiple testing across the 211 phenotypes yielded 42 SNPs that were either disease- or phenotype-associated with seven predominately immune related including self-reported allergy; esophageal cancer was the only cancer phenotype. Motif analyses revealed that only two of these 42 SNPs reside within a canonical VDR binding site (DR3 motif), and that 1/3 of the 42 SNPs significantly impacted binding and gene regulation by other transcription factors, including NF-κB. This suggests a plausible link for the potential cross-talk between VDR and NF-κB.

Conclusions

These analyses showed that VDR peaks are enriched for SNPs associated with immune phenotypes suggesting that VDR immunomodulatory functions are amongst its most important actions. The enrichment of genetic variation in non-DR3 motifs suggests a significant role for the VDR to bind in multimeric complexes containing other transcription factors that are the primary DNA binding component. Our work provides a framework for the combination of ChIP-seq and GWAS findings to provide insight into the underlying phenotype-associated biology of a given transcription factor.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3481-4) contains supplementary material, which is available to authorized users.

PALB2, CHEK2 and ATM rare variants and cancer risk: data from COGS

BACKGROUND

The rarity of mutations in PALB2, CHEK2 and ATM make it difficult to estimate precisely associated cancer risks. Population-based family studies have provided evidence that at least some of these mutations are associated with breast cancer risk as high as those associated with rare BRCA2 mutations. We aimed to estimate the relative risks associated with specific rare variants in PALB2, CHEK2 and ATM via a multicentre case-control study.

METHODS

We genotyped 10 rare mutations using the custom iCOGS array: PALB2 c.1592delT, c.2816T>G and c.3113G>A, CHEK2 c.349A>G, c.538C>T, c.715G>A, c.1036C>T, c.1312G>T, and c.1343T>G and ATM c.7271T>G. We assessed associations with breast cancer risk (42 671 cases and 42 164 controls), as well as prostate (22 301 cases and 22 320 controls) and ovarian (14 542 cases and 23 491 controls) cancer risk, for each variant.

RESULTS

For European women, strong evidence of association with breast cancer risk was observed for PALB2 c.1592delT OR 3.44 (95% CI 1.39 to 8.52, p=7.1×10-5), PALB2 c.3113G>A OR 4.21 (95% CI 1.84 to 9.60, p=6.9×10-8) and ATM c.7271T>G OR 11.0 (95% CI 1.42 to 85.7, p=0.0012). We also found evidence of association with breast cancer risk for three variants in CHEK2, c.349A>G OR 2.26 (95% CI 1.29 to 3.95), c.1036C>T OR 5.06 (95% CI 1.09 to 23.5) and c.538C>T OR 1.33 (95% CI 1.05 to 1.67) (p≤0.017). Evidence for prostate cancer risk was observed for CHEK2 c.1343T>G OR 3.03 (95% CI 1.53 to 6.03, p=0.0006) for African men and CHEK2 c.1312G>T OR 2.21 (95% CI 1.06 to 4.63, p=0.030) for European men. No evidence of association with ovarian cancer was found for any of these variants.

CONCLUSIONS

This report adds to accumulating evidence that at least some variants in these genes are associated with an increased risk of breast cancer that is clinically important.

Assessment of variation in immunosuppressive pathway genes reveals TGFBR2 to be associated with risk of clear cell ovarian cancer

BACKGROUND

Regulatory T (Treg) cells, a subset of CD4+ T lymphocytes, are mediators of immunosuppression in cancer, and, thus, variants in genes encoding Treg cell immune molecules could be associated with ovarian cancer.

METHODS

In a population of 15,596 epithelial ovarian cancer (EOC) cases and 23,236 controls, we measured genetic associations of 1,351 SNPs in Treg cell pathway genes with odds of ovarian cancer and tested pathway and gene-level associations, overall and by histotype, for the 25 genes, using the admixture likelihood (AML) method. The most significant single SNP associations were tested for correlation with expression levels in 44 ovarian cancer patients.

RESULTS

The most significant global associations for all genes in the pathway were seen in endometrioid ( p = 0.082) and clear cell ( p = 0.083), with the most significant gene level association seen with TGFBR2 ( p = 0.001) and clear cell EOC. Gene associations with histotypes at p < 0.05 included: IL12 ( p = 0.005 and p = 0.008, serous and high-grade serous, respectively), IL8RA ( p = 0.035, endometrioid and mucinous), LGALS1 ( p = 0.03, mucinous), STAT5B ( p = 0.022, clear cell), TGFBR1 ( p = 0.021 endometrioid) and TGFBR2 ( p = 0.017 and p = 0.025, endometrioid and mucinous, respectively).

CONCLUSIONS

Common inherited gene variation in Treg cell pathways shows some evidence of germline genetic contribution to odds of EOC that varies by histologic subtype and may be associated with mRNA expression of immune-complex receptor in EOC patients.

Single nucleotide variants in metastasis-related genes are associated with breast cancer risk, by lymph node involvement and estrogen receptor status, in women with European and African ancestry

Single nucleotide polymorphisms (SNPs) in pathways influencing lymph node (LN) metastasis and estrogen receptor (ER) status in breast cancer may partially explain inter-patient variability in prognosis. We examined 154 SNPs in 12 metastasis-related genes for associations with breast cancer risk, stratified by LN and ER status, in European-American (EA) and African-American (AA) women. Two-thousand six hundred and seventy-one women enrolled in the Women's Circle of Health Study were genotyped. Pathway analyses were conducted using the adaptive rank truncated product (ARTP) method, with p_ARTP  ≤ 0.10 as significant. Multi-allelic risk scores were created for the ARTP-significant gene(s). Single-SNP and risk score associations were modeled using logistic regression, with false discovery rate (FDR) P-value adjustment. Although single-SNP associations were not significant at p_FDR  < 0.05, several genes were significant in the ARTP analyses. In AA women, significant ARTP gene-level associations included CDH1 with LN+ (p_ARTP  = 0.10; multi-allelic OR = 1.13, 95%CI 1.07-1.19, p_FDR  = 0.0003) and SIPA1 with ER- breast cancer (p_ARTP  = 0.10; multi-allelic OR = 1.16, 95%CI 1.02-1.31, p_FDR  = 0.03). In EA women, MTA2 was associated with overall breast cancer risk (p_ARTP  = 0.004), regardless of ER status, and with LN- disease (p_ARTP  = 0.01). Also significant were SATB1 in ER- (p_ARTP  = 0.03; multi-allelic OR = 1.12, 95%CI 1.05-1.20, p_FDR  = 0.003) and KISS1 in LN- (p_ARTP  = 0.10; multi-allelic OR = 1.18, 95%CI 1.08-1.29, p_FDR  = 0.002) analyses. Among LN+ cases, significant ARTP associations were observed for SNAI1, CD82, NME1, and CTNNB1 (multi-allelic OR = 1.09, 95%CI 1.04-1.14, p_FDR  = 0.001). Our findings suggest that variants in several metastasis genes may affect breast cancer risk by LN or ER status, although verification in larger studies is required. © 2016 Wiley Periodicals, Inc.

An exome-wide analysis of low frequency and rare variants in relation to risk of breast cancer in African American Women: the AMBER Consortium

A large percentage of breast cancer heritability remains unaccounted for, and most of the known susceptibility loci have been established in European and Asian populations. Rare variants may contribute to the unexplained heritability of this disease, including in women of African ancestry (AA). We conducted an exome-wide analysis of rare variants in relation to risk of overall and subtype-specific breast cancer in the African American Breast Cancer Epidemiology and Risk (AMBER) Consortium, which includes data from four large studies of AA women. Genotyping on the Illumina Human Exome Beadchip yielded data for 170 812 SNPs and 8287 subjects: 3629 cases (1093 estrogen receptor negative (ER-), 1968 ER+, 568 ER unknown) and 4658 controls, the largest exome chip study to date for AA breast cancer. Pooled gene-based association analyses were performed using the unified optimal sequence kernel association test (SKAT-O) for variants with minor allele frequency (MAF) ≤ 5%. In addition, each variant with MAF >0.5% was tested for association using logistic regression. There were no significant associations with overall breast cancer. However, a novel gene, FBXL22 (P = 8.2×10(-6)), and a gene previously identified in GWAS of European ancestry populations, PDE4D (P = 1.2×10(-6)), were significantly associated with ER- breast cancer after correction for multiple testing. Cases with the associated rare variants were also negative for progesterone and human epidermal growth factor receptors-thus, triple-negative cancer. Replication is required to confirm these gene-level associations, which are based on very small counts at extremely rare SNPs.

Chronic Recreational Physical Inactivity and Epithelial Ovarian Cancer Risk: Evidence from the Ovarian Cancer Association Consortium

BACKGROUND

Despite a large body of literature evaluating the association between recreational physical activity and epithelial ovarian cancer (EOC) risk, the extant evidence is inconclusive, and little is known about the independent association between recreational physical inactivity and EOC risk. We conducted a pooled analysis of nine studies from the Ovarian Cancer Association Consortium to investigate the association between chronic recreational physical inactivity and EOC risk.

METHODS

In accordance with the 2008 Physical Activity Guidelines for Americans, women reporting no regular, weekly recreational physical activity were classified as inactive. Multivariable logistic regression was utilized to estimate the ORs and 95% confidence intervals (CI) for the association between inactivity and EOC risk overall and by subgroups based upon histotype, menopausal status, race, and body mass index.

RESULTS

The current analysis included data from 8,309 EOC patients and 12,612 controls. We observed a significant positive association between inactivity and EOC risk (OR = 1.34; 95% CI, 1.14-1.57), and similar associations were observed for each histotype.

CONCLUSIONS

In this large pooled analysis examining the association between recreational physical inactivity and EOC risk, we observed consistent evidence of an association between chronic inactivity and all EOC histotypes.

IMPACT

These data add to the growing body of evidence suggesting that inactivity is an independent risk factor for cancer. If the apparent association between inactivity and EOC risk is substantiated, additional work via targeted interventions should be pursued to characterize the dose of activity required to mitigate the risk of this highly fatal disease. Cancer Epidemiol Biomarkers Prev; 25(7); 1114-24. ©2016 AACR.

Gene-based analysis of the fibroblast growth factor receptor signaling pathway in relation to breast cancer in African American women: the AMBER consortium

We conducted gene-based analysis in 26 genes in the FGFR signaling pathway to identify genes carrying genetic variation affecting risk of breast cancer and the specific estrogen receptor (ER) subtypes. Tagging single-nucleotide polymorphisms (SNPs) for each gene were selected and genotyped on a customized Illumina Exome Array. Imputation was carried out using 1000 Genomes haplotypes. The analysis included 3237 SNPs in 3663 breast cancer cases (including 1983 ER-positive, and 1098 ER-negative) and 4687 controls from the African American Breast Cancer Epidemiology and Risk consortium, a collaborative project of four large studies of breast cancer in African American women (Carolina Breast Cancer Study, Black Women's Health Study, Women's Circle of Health Study, and Multiethnic Cohort). We used a multi-locus adaptive joint (AdaJoint) test to determine the association of each gene in the FGFR signaling pathway with overall breast cancer and ER subtypes. The FGF1 gene was significantly associated with risk of ER-negative breast cancer (P = 0.001). The FGFR2 gene was associated with risk of overall breast cancer (P = 0.002) and ER-positive breast cancer (P = 0.002). The FGF1 gene affects risk of ER-negative breast cancer in African American women. We confirmed the association of the FGFR2 gene with risk of overall and ER-positive breast cancer. These results highlight the importance of the FGFR signaling pathway in the pathogenesis of breast cancer, and suggest that different genes in the same pathway may be associated with different ER breast cancer subtypes.

Family History of Cancer in Relation to Breast Cancer Subtypes in African American Women

BACKGROUND

The evidence on the relation of family history of cancers other than breast cancer to breast cancer risk is conflicting, and most studies have not assessed specific breast cancer subtypes.

METHODS

We assessed the relation of first-degree family history of breast, prostate, lung, colorectal, ovarian, and cervical cancer and lymphoma or leukemia, to the risk of estrogen receptor-positive (ER(+)), ER(-), and triple-negative breast cancer in data from the African American Breast Cancer Epidemiology and Risk Consortium. Multivariable logistic regression models were used to calculate ORs and 95% confidence intervals (CI).

RESULTS

There were 3,023 ER(+) and 1,497 ER(-) breast cancer cases (including 696 triple-negative cases) and 17,420 controls. First-degree family history of breast cancer was associated with increased risk of each subtype: OR = 1.76 (95% CI, 1.57-1.97) for ER(+), 1.67 (1.42-1.95) for ER(-), and 1.72 (1.38-2.13) for triple-negative breast cancer. Family history of cervical cancer was associated with increased risk of ER(-) (OR = 2.39; 95% CI, 1.36-4.20), but not ER(+) cancer. Family history of both breast and prostate cancer was associated with increased risk of ER(+) (3.40; 2.42-4.79) and ER(-) (2.09; 1.21-3.63) cancer, but family history of both breast and lung cancer was associated only with ER(-) cancer (2.11; 1.29-3.46).

CONCLUSIONS

A family history of cancers other than breast may influence the risk of breast cancer, and associations may differ by subtype.

IMPACT

Greater surveillance and counseling for additional screening may be warranted for women with a family history of cancer.

Network-Based Integration of GWAS and Gene Expression Identifies a HOX-Centric Network Associated with Serous Ovarian Cancer Risk

BACKGROUND

Genome-wide association studies (GWAS) have so far reported 12 loci associated with serous epithelial ovarian cancer (EOC) risk. We hypothesized that some of these loci function through nearby transcription factor (TF) genes and that putative target genes of these TFs as identified by coexpression may also be enriched for additional EOC risk associations.

METHODS

We selected TF genes within 1 Mb of the top signal at the 12 genome-wide significant risk loci. Mutual information, a form of correlation, was used to build networks of genes strongly coexpressed with each selected TF gene in the unified microarray dataset of 489 serous EOC tumors from The Cancer Genome Atlas. Genes represented in this dataset were subsequently ranked using a gene-level test based on results for germline SNPs from a serous EOC GWAS meta-analysis (2,196 cases/4,396 controls).

RESULTS

Gene set enrichment analysis identified six networks centered on TF genes (HOXB2, HOXB5, HOXB6, HOXB7 at 17q21.32 and HOXD1, HOXD3 at 2q31) that were significantly enriched for genes from the risk-associated end of the ranked list (P < 0.05 and FDR < 0.05). These results were replicated (P < 0.05) using an independent association study (7,035 cases/21,693 controls). Genes underlying enrichment in the six networks were pooled into a combined network.

CONCLUSION

We identified a HOX-centric network associated with serous EOC risk containing several genes with known or emerging roles in serous EOC development.

IMPACT

Network analysis integrating large, context-specific datasets has the potential to offer mechanistic insights into cancer susceptibility and prioritize genes for experimental characterization.

Abstract 2790: Gene-based analysis of the fibroblast growth factor receptor signaling pathway identifies an association of the FGF1 gene with risk of estrogen receptor-negative breast cancer: The AMBER consortium

Fibroblast growth factors (FGFs) and their receptors (FGFRs) play key roles in several cellular processes such as differentiation, proliferation, migration and survival. Deregulation of the FGFR signaling pathway has been associated with human cancer including breast cancer, and GWAS-identified polymorphisms in the FGFR2 gene have been associated with risk of both overall and estrogen receptor (ER)-positive breast cancer. We conducted gene-based analysis in 26 genes in the FGFR signaling pathway to identify genes carrying genetic variation affecting risk of breast cancer and the specific ER subtypes. Tagging single nucleotide polymorphisms (SNPs) at ±10 kb of each gene were selected and genotyped in a customized Illumina Exome Array. Imputation was carried out using 1000 Genomes haplotypes. The analysis included 9,264 SNPs in 3,663 breast cancer cases (including 1,983 estrogen receptor-positive (ER+), and 1,098 estrogen receptor-negative (ER-)) and 4,687 controls from the African American Breast Cancer Epidemiology and Risk (AMBER) consortium, a collaborative study of four of the largest studies of breast cancer in African American women (Carolina Breast Cancer Study, Black Women's Health Study, Women's Circle of Health Study, and Multi-Ethnic Cohort). We used the adaptive rank-truncated product (ARTP) method implemented in R-package PIGE to determine the association of each gene in the FGFR signaling pathway with overall breast cancer, and ER subtypes. Analyses were adjusted for principal components of genetic variation to control for population stratification, age, geographic region of residence, study, and source of DNA. An alpha level of 0.002 ( = 0.05/26 genes) was used to determine statistical significance at the gene-wide level. After adjustment for multiple testing the FGF1 gene was associated with risk of ER-negative breast cancer (p = 0.001). The FGF1 gene codes for the fibroblast growth factor 1. Genetic variation in this gene has been reported to be associated with risk of ovarian cancer and with breast cancer survival. As expected, the FGFR2 gene was associated with risk of overall breast cancer (p = 0.001) and ER-positive breast cancer (p = 0.002). In summary, we found that the FGF1 gene affects risk of ER-negative breast cancer in African American women, and we confirmed the association of the FGFR2 gene with risk of overall and ER-positive breast cancer. These results highlight the importance of the FGFR signaling pathway in the pathogenesis of breast cancer, and suggest that different genes in the same pathway may be associated with different ER breast cancer subtypes.

Citation Format: Edward A. Ruiz-Narvaez, Stephen Haddad, Christopher A. Haiman, Song Yao, Lara E. Sucheston-Campbell, Jeanette T. Bensen, Kathryn L. Lunetta, Andrew F. Olshan, Christine B. Ambrosone, Julie R. Palmer. Gene-based analysis of the fibroblast growth factor receptor signaling pathway identifies an association of the FGF1 gene with risk of estrogen receptor-negative breast cancer: The AMBER consortium. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2790. doi:10.1158/1538-7445.AM2015-2790

Establishment of Definitions and Review Process for Consistent Adjudication of Cause-specific Mortality after Allogeneic Unrelated-donor Hematopoietic Cell Transplantation

Clinical trials commonly use adjudication committees to refine endpoints, but observational research or genome-wide association studies rarely do. Our goals were to establish definitions of cause-specific death after unrelated-donor allogeneic hematopoietic cell transplantation (URD-HCT), to estimate discordance between reported and adjudicated cause-specific death, and to identify factors contributing to inconsistency in cause-specific death determination. A consensus panel adjudicated cause-specific death in 1484 patients who died within 1 year after HCT, derived from 3532 acute leukemia or myelodysplasia patients after URD-HCT from 2000 to 2011 reported by 151 US transplant centers to the Center for International Blood and Marrow Transplant Research. Deaths were classified as disease-related or transplant-related. The panel agreed with >99% of deaths reported by centers as disease-related and 80% reported as transplant-related. Year of transplant (cohort effect) and disease status significantly influenced agreement between the panel and centers. Sensitivity analysis of deaths < 100 days post-transplant yielded the lowest agreement between the panel and centers for myelodysplastic syndrome patients. Standard predefined criteria for adjudicating cause-specific death led to consistent application to similar clinical scenarios and clearer delineation of cause-specific death categories. Other studies of competing events such as cancer-specific versus treatment-related mortality would benefit from our results. Our detailed algorithm should result in more consistent reporting of cause-specific death by centers.

Vitamin D receptor and RXR in the post-genomic era

Following the elucidation of the human genome and components of the epigenome, it is timely to revisit what is known of vitamin D receptor (VDR) function. Early transcriptomic studies using microarray approaches focused on the protein coding mRNA that were regulated by the VDR, usually following treatment with ligand. These studies quickly established the approximate size and surprising diversity of the VDR transcriptome, revealing it to be highly heterogenous and cell type and time dependent. Investigators also considered VDR regulation of non-protein coding RNA and again, cell and time dependency was observed. Attempts to integrate mRNA and miRNA regulation patterns are beginning to reveal patterns of co-regulation and interaction that allow for greater control of mRNA expression, and the capacity to govern more complex cellular events. Alternative splicing in the trasncriptome has emerged as a critical process in transcriptional control and there is evidence of the VDR interacting with components of the splicesome. ChIP-Seq approaches have proved to be pivotal to reveal the diversity of the VDR binding choices across cell types and following treatment, and have revealed that the majority of these are non-canonical in nature. The underlying causes driving the diversity of VDR binding choices remain enigmatic. Finally, genetic variation has emerged as important to impact the transcription factor affinity towards genomic binding sites, and recently the impact of this on VDR function has begun to be considered.

VDR regulation of microRNA differs across prostate cell models suggesting extremely flexible control of transcription

The Vitamin D Receptor (VDR) is a member of the nuclear receptor superfamily and is of therapeutic interest in cancer and other settings. Regulation of microRNA (miRNA) by the VDR appears to be important to mediate its actions, for example, to control cell growth. To identify if and to what extent VDR-regulated miRNA patterns change in prostate cancer progression, we undertook miRNA microarray analyses in 7 cell models representing non-malignant and malignant prostate cells (RWPE-1, RWPE-2, HPr1, HPr1AR, LNCaP, LNCaP-C4-2, and PC-3). To focus on primary VDR regulatory events, we undertook expression analyses after 30 minutes treatment with 1α,25(OH)2D3. Across all models, 111 miRNAs were significantly modulated by 1α,25(OH)2D3 treatment. Of these, only 5 miRNAs were modulated in more than one cell model, and of these, only 3 miRNAs were modulated in the same direction. The patterns of miRNA regulation, and the networks they targeted, significantly distinguished the different cell types. Integration of 1α,25(OH)2D3-regulated miRNAs with published VDR ChIP-seq data showed significant enrichment of VDR peaks in flanking regions of miRNAs. Furthermore, mRNA and miRNA expression analyses in non-malignant RWPE-1 cells revealed patterns of miRNA and mRNA co-regulation; specifically, 13 significant reciprocal patterns were identified and these patterns were also observed in TCGA prostate cancer data. Lastly, motif search analysis revealed differential motif enrichment within VDR peaks flanking mRNA compared to miRNA genes. Together, this study revealed that miRNAs are rapidly regulated in a highly cell-type specific manner, and are significantly co-integrated with mRNA regulation.

Serum microRNA expression patterns that predict early treatment failure in prostate cancer patients

We aimed to identify microRNA (miRNA) expression patterns in the serum of prostate cancer (CaP) patients that predict the risk of early treatment failure following radical prostatectomy (RP). Microarray and Q-RT-PCR analyses identified 43 miRNAs as differentiating disease stages within 14 prostate cell lines and reflectedpublically available patient data. 34 of these miRNA were detectable in the serum of CaP patients. Association with time to biochemical progression was examined in a cohort of CaP patients following RP. A greater than two-fold increase in hazard of biochemical progression associated with altered expression of miR-103, miR-125b and miR-222 (p <.0008) in the serum of CaP patients. Prediction models based on penalized regression analyses showed that the levels of the miRNAs and PSA together were better at detecting false positives than models without miRNAs, for similar level of sensitivity. Analyses of publically available data revealed significant and reciprocal relationships between changes in CpG methylation and miRNA expression patterns suggesting a role for CpG methylation to regulate miRNA. Exploratory validation supported roles for miR-222 and miR-125b to predict progression risk in CaP. The current study established that expression patterns of serum-detectable miRNAs taken at the time of RP are prognostic for men who are at risk of experiencing subsequent early biochemical progression. These non-invasive approaches could be used to augment treatment decisions.

Variants of estrogen-related genes and breast cancer risk in European and African American women

It has been observed previously that compared with women of European ancestry (EA), those of African ancestry (AA) are more likely to develop estrogen receptor (ER)-negative breast cancer, although the mechanisms have not been elucidated. We tested the associations between breast cancer risk and a targeted set of 20 genes known to be involved in estrogen synthesis, metabolism, and response and potential gene-environment interactions using data and samples from 1307 EA (658 cases) and 1365 AA (621 cases) participants from the Women's Circle of Health Study (WCHS). Multivariable logistic regression found evidence of associations with single-nucleotide polymorphisms (SNPs) in the ESR1 gene in EA women (rs1801132, odds ratio (OR)=1.47, 95% CI=1.20-1.80, P=0.0002; rs2046210, OR=1.24, 95% CI=1.04-1.47, P=0.02; and rs3020314, OR=1.43, 95% CI=1.19-1.70, P=0.00009), but not in AA women. The only other gene associated with breast cancer risk was CYP1A2 in AA women (rs2470893, OR=1.42, 95% CI=1.00-2.02, P=0.05), but not in EA women. When stratified by ER status, ESR1 rs1801132, rs2046210, and rs3020314 showed stronger associations in ER-positive than in ER-negative breast cancer in only EA women. Associations with the ESR1 SNPs in EA women also appeared to be stronger with longer endogenous estrogen exposure or hormonal replacement therapy use. Our results indicate that there may be differential genetic influences on breast cancer risk in EA compared with AA women and that these differences may be modified by tumor subtype and estrogen exposures. Future studies with a larger sample size may determine the full contribution of estrogen-related genes to racial/ethnic differences in breast cancer.

Cooperative behavior of the nuclear receptor superfamily and its deregulation in prostate cancer

The current study aimed to assess the topology of the nuclear receptor (NR) superfamily in normal prostate epithelial cells and its distortion in prostate cancer. Both in vitro and in silico approaches were utilized to profile NRs expressed in non-malignant RWPE-1 cells, which were subsequently investigated by treating cells with 132 binary NR ligand combinations. Nine significant cooperative interactions emerged including both superadditive [22(R)-hydroxycholesterol and eicosatetraenoic acid] and subadditive [1α,25(OH)2D3 and chenodeoxycholic acid] cellular responses, which could be explained in part by cooperative control of cell-cycle progression and candidate gene expression. In addition, publicly available data were employed to assess NR expression in human prostate tissue. Common and significant loss of NR superfamily expression was established in publicly available data from prostate tumors, in part predicting parallel distortion of targeting microRNA. These findings suggest that the NR superfamily in the prostate cooperatively integrates signals from dietary, hormonal and metabolic cues, and is significantly distorted in prostate cancer.