Mutation Screening of 1,237 Cancer Genes across Six Model Cell Lines of Basal-Like Breast Cancer

Development and validation of a glycolysis-associated gene signature for predicting the prognosis, immune landscape, and drug sensitivity in bladder cancer

Background

Bladder cancer (BCa) is one of the most common malignancies worldwide, and its prognostication and treatment remains challenging. The fast growth of various cancer cells requires reprogramming of its energy metabolism using aerobic glycolysis as a major energy source. However, the prognostic and therapeutic value of glycolysis-related genes in BCa remains to be determined.

Methods

The fused merge dateset from TCGA, GSE13507 and GSE31684 were used for the analysis of glycolysis-related genes expression or subtyping; and corresponding clinical data of these BCa patients were also collected. In the merge cohort, we constructed a 18 multigene signature using the least absolute shrinkage and selection operator (LASSO) Cox regression model. The four external cohorts (i.e., IMvigor210, GSE32894, GSE48276 and GSE48075) of BCa patients were used to validate the accuracy. We evaluated immune infiltration using seven published algorithms: CIBERSORT, QUANTISEQ, XCELL, TIMER, CIBERSORT-ABS, EPIC, and MCPCOUNTER. Subsequently, in order to analyze the correlation between risk groups(scores) and overall survival, recognised immunoregolatory cells or common chemotherapeutic agents, clinicopathological data and immune checkpoint-related genes of BCa patients, Wilcox rank test, chi-square test, cox regression and spearman's correlation were performed.

Results

Conspicuously, we could see that CD8+ T, cancer associated fibroblast, macrophage M2, NK, endothelial cells and so on were significantly dysregulated between the two risk groups. In addition, compared with the low-risk group, high-risk group predicted poor prognosis and relatively weak sensitivity of chemotherapy. Additionally, we also found that the expression level of partial genes in the model was significantly correlated with objective responses to anti-PD-1 or anti-PD-L1 treatment in the IMvigor210, GSE111636, GSE176307, GSE78220 or GSE67501 cohort; and its expression level was also varied in different objective response cases receiving tislelizumab combined with low-dose nab-paclitaxel therapy based on our mRNA sequencing (TRUCE-01). According to "GSEA" algorithm of R package "clusterProfiler", the most significantly enriched HALLMARK, KEGG pathway and GO term was separately the 'Epithelial Mesenchymal Transition', 'Ecm Receptor Interaction' and 'MF_Extracellular_matrix_structural_constitunet' in the high- vs. low-risk group. Subsequently, we verified the protein and mRNA expression of interested model-related genes from the Human Protein Atlas (HPA) and 10 paired BCa tissues collected by us. Furthermore, in vitro functional experiments demonstrated that FASN was a functional oncogene in BCa cells through promoting cell proliferation, migration, and invasion abilities.

Conclusion

In summary, the glycolysis-associated gene signature established by us exhibited a high predictive performance for the prognosis, immunotherapeutic responsiveness, and chemotherapeutic sensitivity of BCa. And, The model also might function as a chemotherapy and immune checkpoint inhibitor (ICI) treatment guidance.

DNA Repair Genes as Drug Candidates for Early Breast Cancer Onset in Latin America: A Systematic Review

The prevalence of breast cancer in young women (YWBC) has increased alarmingly. Significant efforts are being made to elucidate the biological mechanisms concerning the development, prognosis, and pathological response in early-onset breast cancer (BC) patients. Dysfunctional DNA repair proteins are implied in BC predisposition, progression, and therapy response, underscoring the need for further analyses on DNA repair genes. Public databases of large patient datasets such as METABRIC, TCGA, COSMIC, and cancer cell lines allow the identification of variants in DNA repair genes and possible precision drug candidates. This study aimed at identifying variants and drug candidates that may benefit Latin American (LA) YWBC. We analyzed pathogenic variants in 90 genes involved in DNA repair in public BC datasets from METABRIC, TCGA, COSMIC, CCLE, and COSMIC Cell Lines Project. Results showed that reported DNA repair germline variants in the LA dataset are underrepresented in large databases, in contrast to other populations. Additionally, only six gene repair variants in women under 50 years old from the study population were reported in BC cell lines. Therefore, there is a need for new approaches to study DNA repair variants reported in young women from LA.

Breast Cancer Antiestrogen Resistance 3 (BCAR3) promotes tumor growth and progression in triple-negative breast cancer

Triple-Negative Breast Cancers (TNBCs) constitute roughly 10-20% of breast cancers and are associated with poor clinical outcomes. Previous work from our laboratory and others has determined that the cytoplasmic adaptor protein Breast Cancer Antiestrogen Resistance 3 (BCAR3) is an important promoter of cell motility and invasion of breast cancer cells. In this study, we use both in vivo and in vitro approaches to extend our understanding of BCAR3 function in TNBC. We show that BCAR3 is upregulated in ductal carcinoma in situ (DCIS) and invasive carcinomas compared to normal mammary tissue, and that survival of TNBC patients whose tumors contained elevated BCAR3 mRNA is reduced relative to individuals whose tumors had less BCAR3 mRNA. Using mouse orthotopic tumor models, we further show that BCAR3 is required for efficient TNBC tumor growth. Analysis of publicly available RNA expression databases revealed that MET receptor signaling is strongly correlated with BCAR3 mRNA expression. A functional role for BCAR3-MET coupling is supported by data showing that both proteins participate in a single pathway to control proliferation and migration of TNBC cells. Interestingly, the mechanism through which this functional interaction operates appears to differ in different genetic backgrounds of TNBC, stemming in one case from potential differences in the strength of downstream signaling by the MET receptor and in another from BCAR3-dependent activation of an autocrine loop involving the production of HGF mRNA. Together, these data open the possibility for new approaches to personalized therapy for individuals with TNBCs.

NOTCH and EZH2 collaborate to repress PTEN expression in breast cancer

Downregulation of the PTEN tumor suppressor transcript is frequent in breast cancer and associates with poor prognosis and triple-negative breast cancer (TNBC) when comparing breast cancers to one another. Here we show that in almost all cases, when comparing breast tumors to adjacent normal ducts, PTEN expression is decreased and the PRC2-associated methyltransferase EZH2 is increased. We further find that when comparing breast cancer cases in large cohorts, EZH2 inversely correlates with PTEN expression. Within the highest EZH2 expressing group, NOTCH alterations are frequent, and also associate with decreased PTEN expression. We show that repression of PTEN occurs through the combined action of NOTCH (NOTCH1 or NOTCH2) and EZH2 alterations in a subset of breast cancers. In fact, in cases harboring NOTCH1 mutation or a NOTCH2 fusion gene, NOTCH drives EZH2, HES-1, and HEY-1 expression to repress PTEN transcription at the promoter, which may contribute to poor prognosis in this subgroup. Restoration of PTEN expression can be achieved with an EZH2 inhibitor (UNC1999), a γ-secretase inhibitor (Compound E), or knockdown of EZH2 or NOTCH. These findings elucidate a mechanism of transcriptional repression of PTEN induced by NOTCH1 or NOTCH2 alterations, and identifies actionable signaling pathways responsible for driving a large subset of poor-prognosis breast cancers.

Pappas et al. show that the combination of NOTCH and EZH2 alterations drive transcriptional repression of PTEN through reversible epigenetic modification of the PTEN promoter. These results suggest an actionable target for treating poor-prognosis breast cancer.

Mechanisms of HERV-K (HML-2) Transcription during Human Mammary Epithelial Cell Transformation

Increasing evidence suggests that repetitive elements may play a role in host gene regulation, particularly through the donation of alternative promoters, enhancers, splice sites, and termination signals. Elevated transcript expression of the endogenous retrovirus group HERV-K (HML-2) is seen in many human cancers, although the identities of the individual proviral loci contributing to this expression as well as their mechanisms of activation have been unclear. Using high-throughput next-generation sequencing techniques optimized for the capture of HML-2 expression, we characterized the HML-2 transcriptome and means of activation in an in vitro model of human mammary epithelial cell transformation. Our analysis showed significant expression originating from 15 HML-2 full-length proviruses, through four modes of transcription. The majority of expression was in the antisense orientation and from proviruses integrated within introns. We found two instances of long terminal repeat (LTR)-driven provirus transcription but no evidence to suggest that these active 5' LTRs were influencing nearby host gene expression. Importantly, LTR-driven transcription was restricted to tumorigenic cells, suggesting that LTR promoter activity is dependent upon the transcriptional environment of a malignant cell.IMPORTANCE Here, we use an in vitro model of human mammary epithelial cell transformation to assess how malignancy-associated shifts in the transcriptional milieu of a cell may impact HML-2 activity. We found 15 proviruses to be significantly expressed through four different mechanisms, with the majority of transcripts being antisense copies of proviruses located within introns. We saw active 5' LTR use in tumorigenic cells only, suggesting that the cellular environment of a cancer cell is a critical component for induction of LTR promoter activity. These findings have implications for future studies investigating HML-2 as a target for immunotherapy or as a biomarker for disease.

DIP2C expression in breast cancer and its clinical significance

INTRODUCTION

The aim of this study was to investigate DIP2C expression in different subtypes of breast cancer tissues and cell lines and its correlation with clinicopathologic and histopathological features, in an effort to elucidate the DIP2C expression profile in breast cancer and its clinical significance.

METHODS

Hereby, we investigated the DIP2C expression in breast cancer tissues using TMA-IHC method and the DIP2C expression in breast cell lines using quantitative RT-PCR.

RESULTS

DIP2C displayed universal expression, being present in all the breast cancer subtypes. There were more cases that staining weakly in breast cancer tissues (n=79/150, 52.7%) than that in fibroadenomas tissues (n=2/18, 11.1%) and normal tissues (n=2/20, 10.0%) (χ2=21.84, P <0.001). Within different intrinsic subtypes of breast cancer assayed by IHC expression profiles, there were less cases of the strongly staining group in basal-like subtype (n=38/86, 44.2%) and HER-2 subtype (n=6/24, 25.0%) than that in luminal A (14/20, 70%) and luminal B (13/20, 65%) subtypes (χ2=11.77, p=0.008). Furthermore, DIP2C expression was positive correlated with ER (χ2=8.90, p=0.003) and PR expression (χ2=10.94, p=0.001), while negative correlated with EGFR expression (χ2=9.27, p=0.002), in accordance with the results of cell lines with different subtypes. Oncomine database also confirmed that, DIP2C was expressed lower in breast cancer tissues, and could indicate prognosis.

CONCLUSION

our data revealed DIP2C expression level decreased in breast cancer, especially in basal-like and HER-2 subtypes, and could be a valuable target for diagnosis on specific subtype of breast cancer.