Diabetes-associated breast cancer is molecularly distinct and shows a DNA damage repair deficiency

Diabetes commonly affects patients with cancer. We investigated the influence of diabetes on breast cancer biology using a 3-pronged approach that included analysis of orthotopic human tumor xenografts, patient tumors, and breast cancer cells exposed to diabetes/hyperglycemia-like conditions. We aimed to identify shared phenotypes and molecular signatures by investigating the metabolome, transcriptome, and tumor mutational burden. Diabetes and hyperglycemia did not enhance cell proliferation but induced mesenchymal and stem cell-like phenotypes linked to increased mobility and odds of metastasis. They also promoted oxyradical formation and both a transcriptome and mutational signatures of DNA repair deficiency. Moreover, food- and microbiome-derived metabolites tended to accumulate in breast tumors in the presence of diabetes, potentially affecting tumor biology. Breast cancer cells cultured under hyperglycemia-like conditions acquired increased DNA damage and sensitivity to DNA repair inhibitors. Based on these observations, we conclude that diabetes-associated breast tumors may show an increased drug response to DNA damage repair inhibitors.

Population-specific Mutation Patterns in Breast Tumors from African American, European American, and Kenyan Patients

Women of African descent have the highest breast cancer mortality in the United States and are more likely than women from other population groups to develop an aggressive disease. It remains uncertain to what extent breast cancer in Africa is reminiscent of breast cancer in African American or European American patients. Here, we performed whole-exome sequencing of genomic DNA from 191 breast tumor and non-cancerous adjacent tissue pairs obtained from 97 African American, 69 European American, 2 Asian American, and 23 Kenyan patients. Our analysis of the sequencing data revealed an elevated tumor mutational burden in both Kenyan and African American patients, when compared with European American patients. TP53 mutations were most prevalent, particularly in African American patients, followed by PIK3CA mutations, which showed similar frequencies in European American, African American, and the Kenyan patients. Mutations targeting TBX3 were confined to European Americans and those targeting the FBXW7 tumor suppressor to African American patients whereas mutations in the ARID1A gene that are known to confer resistance to endocrine therapy were distinctively enriched among Kenyan patients. A Kyoto Encyclopedia of Genes and Genomes pathway analysis could link FBXW7 mutations to an increased mitochondrial oxidative phosphorylation capacity in tumors carrying these mutations. Finally, Catalogue of Somatic Mutations in Cancer (COSMIC) mutational signatures in tumors correlated with the occurrence of driver mutations, immune cell profiles, and neighborhood deprivation with associations ranging from being mostly modest to occasionally robust. To conclude, we found mutational profiles that were different between these patient groups. The differences concentrated among genes with low mutation frequencies in breast cancer.

SIGNIFICANCE

The study describes differences in tumor mutational profiles between African American, European American, and Kenyan breast cancer patients. It also investigates how these profiles may relate to the tumor immune environment and the neighborhood environment in which the patients had residence. Finally, it describes an overrepresentation of ARID1A gene mutations in breast tumors of the Kenyan patients.

Protein expression of the gp78 E3-ligase predicts poor breast cancer outcome based on race

Women of African ancestry suffer higher rates of breast cancer mortality compared to all other groups in the United States. Though the precise reasons for these disparities remain unclear, many recent studies have implicated a role for differences in tumor biology. Using an epitope-validated antibody against the endoplasmic reticulum-associated degradation (ERAD) E3 ubiquitin ligase, gp78, we show that elevated levels of gp78 in patient breast cancer cells predict poor survival. Moreover, high levels of gp78 are associated with poor outcomes in both ER-positive and ER-negative tumors, and breast cancers expressing elevated amounts of gp78 protein are enriched in gene expression pathways that influence cell cycle, metabolism, receptor-mediated signaling, and cell stress response pathways. In multivariate analysis adjusted for subtype and grade, gp78 protein is an independent predictor of poor outcomes in women of African ancestry. Furthermore, gene expression signatures, derived from patients stratified by gp78 protein expression, are strong predictors of recurrence and pathological complete response in retrospective clinical trial data and share many common features with gene sets previously identified to be overrepresented in breast cancers based on race. These findings implicate a prominent role for gp78 in tumor progression and offer new insights into our understanding of racial differences in breast cancer outcomes.

Abstract 2180: Somatic mutation landscape in early-onset colorectal cancer tumors from hispanics

Background: In the last 40 years, the incidence of colorectal cancer (CRC) among individuals <50 years (early-onset CRC) has been increasing at an alarming rate in the US, and is expected to increase by >140% by 2030. Early-onset CRC represents a clinically distinct form of CRC often associated with a poor prognosis. During 2012-2017, more than 11% of the CRC cases in the US and more than 9% of the total CRC cases in Puerto Rico corresponded to patients <50 years old. This highlights the imperative need to describe the genetic drivers of early-onset CRC in Hispanics in order to increase early diagnosis, improve personalized clinical management, and improve survival outcomes. The objective of this study was to characterize the somatic mutation profile of early-onset tumors from Puerto Ricans, a Hispanic subpopulation with a high CRC burden, in order to better understand early-onset CRC biology.

Methods: Whole exome sequencing analyses were performed using the HiSeq4000 System (Illumina) on concordant colorectal adenocarcinoma and colonic mucosa tissue samples from 58 individuals diagnosed with colorectal cancer at <50 years old (early-onset CRC) and 25 individuals diagnosed with CRC >60 years old (late-onset CRC). Somatic variant calling and annotation/visualization were performed using Strelka and Ingenuity Variant Analysis software, respectively. All participants were recruited by Puerto Rico Familial Colorectal Cancer Registry (PURIFICAR).

Results: Early-onset and late-onset CRC tumors showed distinct mutational profiles, only sharing TTN and MUC19 among their top 10 most mutated genes. The most frequently mutated genes in early-onset CRC tumors were: TTN (79%), MUC19 (75%), SYNE1 (68%), PCDHGA1 (68%), LPR1B (67%), PCDHGA2 (67%), PCDHGA3 (65%), PCDHGB1 (%), MUC16 (65%) and PCDHGA4 (65%). In late-onset CRC, the top ten most frequently mutated genes were: CSMD1 (68%), APC (68%), SYNE1 (64%), TTN (60%), MUC19 (60%), MUC16 (60%), PCDHA1 (60%), PCDHB1 (%), PCDHG1 (60%) and PCDHG2 (60%).

Conclusion: This study presents the somatic mutation profile of early-onset colorectal tumors from Puerto Ricans, a Hispanic subgroup with noted CRC health disparities. Somatic mutational profiles were found to be distinct when comparing early-onset and late-onset colorectal tumors. The majority of the somatic mutations detected in the early-onset CRC tumors were in non-coding regions, suggesting that epigenetic regulation may contribute to early-onset colorectal carcinogenesis.

Citation Format: Maria Gonzalez-Pons, Ingrid Montes-Rodriguez, Kelvin Carrasquillo-Carrion, Abiel Roche-Lima, Sandeep Singhal, Anna M. Napoles, Jung S. Byun, Eliseo Perez-Stable, Kevin Gardner, Marcia Cruz-Correa. Somatic mutation landscape in early-onset colorectal cancer tumors from hispanics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2180.

FoxO1 as a Regulator of Aquaporin 5 Expression in the Salivary Gland

Forkhead box O1 (FoxO1) is a multifunctional initiator, mediator, and repressor of autoimmune diseases in an organ- or disease-specific manner. However, the role of FoxO1 in the salivary gland has not yet been elucidated. In this study, we discovered that FoxO1 and aquaporin 5 (AQP5) are both significantly downregulated in the patients with primary Sjögren syndrome, an autoimmune disease accompanying salivary gland dysfunction. Pharmacologic or genetic perturbation of FoxO1 in the rat salivary gland acinar cell line, SMG-C6, induced a significant downregulation of AQP5 expression, as observed in clinical specimens. There was a strong correlation between FoxO1 and AQP5 expression because FoxO1 is a direct regulator of AQP5 expression in salivary gland acinar cells through its interaction with the promoter region of AQP5. Serial injection of a FoxO1 inhibitor into mice induced a reduction of AQP5 expression in submandibular glands and, consequently, hyposalivation, which is one of the major clinical symptoms of primary Sjögren syndrome. However, there was no sign of inflammation or cell damage in the submandibular glands harvested from mice treated with the FoxO1 inhibitor. In conclusion, our findings indicate that FoxO1 in salivary gland tissue acts as a direct regulator of AQP5 expression. Thus, downregulation of FoxO1 observed in primary Sjögren syndrome is a putative mechanism for hyposalivation without the involvement of previously reported soluble factors in primary Sjögren syndrome patient sera.

Kaiso (ZBTB33) subcellular partitioning functionally links LC3A/B, the tumor microenvironment, and breast cancer survival

The use of digital pathology for the histomorphologic profiling of pathological specimens is expanding the precision and specificity of quantitative tissue analysis at an unprecedented scale; thus, enabling the discovery of new and functionally relevant histological features of both predictive and prognostic significance. In this study, we apply quantitative automated image processing and computational methods to profile the subcellular distribution of the multi-functional transcriptional regulator, Kaiso (ZBTB33), in the tumors of a large racially diverse breast cancer cohort from a designated health disparities region in the United States. Multiplex multivariate analysis of the association of Kaiso’s subcellular distribution with other breast cancer biomarkers reveals novel functional and predictive linkages between Kaiso and the autophagy-related proteins, LC3A/B, that are associated with features of the tumor immune microenvironment, survival, and race. These findings identify effective modalities of Kaiso biomarker assessment and uncover unanticipated insights into Kaiso’s role in breast cancer progression.

Through automated image analysis, Singhal et al quantify nuclear versus cytoplasmic distribution of the Kaiso transcription factor in breast cancer patient tissue. They find that Kaiso distribution correlates with breast cancer subtype and overall survival, and discover a link between cytoplasmic Kaiso and autophagy marker LC3.

Whole-Exome Profiling of NSCLC Among African Americans

INTRODUCTION

Lung cancer incidence is higher among African Americans (AAs) compared with European Americans (EAs) in the United States, especially among men. Although significant progress has been made profiling the genomic makeup of lung cancer in EAs, AAs continue to be underrepresented. Our objective was to chart the genome-wide landscape of somatic mutations in lung cancer tumors from AAs.

METHODS

In this study, we used the whole-exome sequencing of 82 tumor and noninvolved tissue pairs from AAs. Patients were selected from an ongoing case-control study conducted by the National Cancer Institute and the University of Maryland.

RESULTS

Among all samples, we identified 178 significantly mutated genes (p < 0.05), five of which passed the threshold for false discovery rate (p < 0.1). In lung adenocarcinoma (LUAD) tumors, mutation rates in STK11 (p = 0.05) and RB1 (p = 0.008) were significantly higher in AA LUAD tumors (25% and 13%, respectively) compared with The Cancer Genome Atlas EA samples (14% and 4%, respectively). In squamous cell carcinomas, mutation rates in STK11 (p = 0.002) were significantly higher among AA (8%) than EA tumors from The Cancer Genome Atlas (1%). Integrated somatic mutation data with CIBERSORT (Cell-type Identification By Estimating Relative Subsets Of RNA Transcripts) data analysis revealed LUAD tumors from AAs carrying STK11 mutations have decreased interferon signaling.

CONCLUSIONS

Although a considerable degree of the somatic mutation landscape is shared between EAs and AAs, discrete differences in mutation frequency in potentially important oncogenes and tumor suppressors exist. A better understanding of the molecular basis of lung cancer in AA patients and leveraging this information to guide clinical interventions may help reduce disparities.

Ancestry-dependent gene expression correlates with reprogramming to pluripotency and multiple dynamic biological processes

Induced pluripotent stem cells (iPSCs) can be derived from differentiated cells, enabling the generation of personalized disease models by differentiating patient-derived iPSCs into disease-relevant cell lines. While genetic variability between different iPSC lines affects differentiation potential, how this variability in somatic cells affects pluripotent potential is less understood. We generated and compared transcriptomic data from 72 dermal fibroblast-iPSC pairs with consistent variation in reprogramming efficiency. By considering equal numbers of samples from self-reported African Americans and White Americans, we identified both ancestry-dependent and ancestry-independent transcripts associated with reprogramming efficiency, suggesting that transcriptomic heterogeneity can substantially affect reprogramming. Moreover, reprogramming efficiency-associated genes are involved in diverse dynamic biological processes, including cancer and wound healing, and are predictive of 5-year breast cancer survival in an independent cohort. Candidate genes may provide insight into mechanisms of ancestry-dependent regulation of cell fate transitions and motivate additional studies for improvement of reprogramming.

Abstract 1183: Race, copy number variation, and local hog concentration in breast cancer mortality

Purpose of study: Female breast cancer is the second leading cause of cancer death in U.S. women, and the incidence of new breast cancer cases continues to increase. Despite slightly lower breast cancer incidence rates among African American (AA) compared to European American (EA) women in the U.S., AA women experience significantly higher breast cancer mortality. To better understand the extent to which environmental and genetic factors might help explain higher mortality rates among AA women, we examined the association between a measure of exposure to chemical pollutants and genomic profiling with breast cancer mortality among women with breast cancer in North Carolina.

Procedures: Using a molecular epidemiologic approach, we examined the association of county hog concentration (a marker of environmental exposure to chemical pollutants) and genomic variations identified via targeted exome sequencing with age-adjusted breast cancer mortality rates among 146 women in North Carolina, stratified by race (AA vs. EA). The odds of breast cancer-specific mortality were estimated as a function of county hog concentration quintiles.

Results: Overall, breast cancer mortality among AA women was higher than among EA women (OR=1.4, p&lt;0.0001). Although there was no effect of hog concentration on breast cancer mortality of EA women, there was an increase in deaths from breast cancer in African American women in the highest quintile of hog concentration (OR=1.18, p=0.03), compared to the lower quintiles. In the lowest quintile of hog concentration, breast cancer mortality remained higher among AA versus EA women (OR=1.38, p=0.0002). This suggests that along with environmental factors, biological factors also contribute to disparities. Next, we performed targeted exome sequencing of breast cancer samples collected from a cohort in eastern North Carolina. AA breast cancer samples showed a high frequency of CNVs (copy number variations) of COL11A2, COL12A1, CYP21A2, LYRM2, COL9A1, DNAH11, and DST. EA breast cancer samples showed a high frequency of CNVs of PRG4, PLB1, CHRM5, OCA2, HMCN1, and MUC5B. Among these, HMCN1, MUC5B (among EA), and COL12A1, DNAH11, DST (among AA) were genes with significantly high CNVs identified from The Cancer Genome Atlas.

Conclusions: Our findings suggest that living in a county with a high concentration of hogs may increase breast cancer mortality risk among AA women, and the high frequency of CNVs varies by race; both CNV and county hog concentration may contribute to racial disparities in breast cancer mortality among AA and EA women in North Carolina.

Citation Format: Jung S. Byun, Sean Lee, Sijung Yun, Eliseo J. Perez-Stable, Anna M. Napoles, Paul Strickland, Kevin L. Gardner. Race, copy number variation, and local hog concentration in breast cancer mortality [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 1183.

Abstract C033: Racial differences in the associations between luminal master regulator transcription factor expression and breast cancer survival

Purpose: Women of African ancestry in the United States are more likely to die from breast cancer than their European counterparts. While prior studies suggest differences in the frequency of hormone receptor-negative disease as an underlying cause, recent studies report higher race-based mortality rates in patients with hormone receptor-positive, luminal breast cancer. Here we explore biologic factors that may underly this disparity by comparing racial differences in the level, functional activity, and prognostic significance of 3 master transcriptional regulators of mammary luminal differentiation.

Patients and Methods: Medical records and tissues from 555 patients (293 European and 262 African ancestry) diagnosed with Stage 0 to IV breast cancer, from 2001 to 2010 at a major medical center in East North Carolina, were analyzed for the expression of functional biomarkers of luminal differentiation including estrogen receptor (ESR1), and pioneer transcription factors FOXA1 and GATA3. Differential comparison of protein expression was integrated with network-level gene expression analysis (22% of cohort) to define predictive correlations with race and survival.

Results: Univariate and multivariate odds ratios combined with area under the curve receiver operator characteristics show significant differences in predictive activity of these functional biomarkers based on race and survival—ESR1 (EA OR= 0.47, p = 5e-04; AA OR= 0.77, p = 0.22), FOXA1 (EA OR= 0.38, p= 1.4e-04; AA OR = 0.53, p = 1.3e-02), and GATA3 (EA OR= 0.36, p= 3.7e-06, AA OR= 0.57, p= 0.51)—and uncover genes in the downstream regulons of these biomarkers that strongly correlate either with genetic ancestry or overall survival.

Conclusion: Transcriptional regulatory networks linked to mammary luminal differentiation reveal race-specific differences in master regulatory activity that may underlie tumor characteristics contributing to racial disparities in outcome. These biomarkers and their downstream regulons represent important targets to explore intrinsic mechanisms that drive breast cancer survival disparities.

Citation Format: Jung S. Byun, Sandeep K. Singhal, Sam Park, Dae Ik Yi, Tingfen Yan, Ambar Caban, Alana Jones, Partha Mukhopadhyay, Sara Gil Hernandez, Stephen Hewitt, Lisa A. Newman, Melissa Davis, Jorge Sepulveda, Adrianna De Siervi, Anna Napoles, Nasreen Vohra, Kevin Gardner. Racial differences in the associations between luminal master regulator transcription factor expression and breast cancer survival [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C033.

Vitamin C supplementation reduces the odds of developing a common cold in Republic of Korea Army recruits: randomised controlled trial

INTRODUCTION

The Republic of Korea (ROK) military has a high incidence of respiratory diseases at training centres. Vitamin C has been reported to reduce the incidence of colds. For the purpose of preventing soldiers' respiratory diseases, this study aimed to investigate whether vitamin C intake can prevent common colds in the ROK Army soldiers.

METHODS

This was a randomised, placebo-controlled, and double-blind trial of soldiers who enlisted in the Korea Army Training Centre for 30 days from 12 February to 13 March 2018. The study participants were divided into groups (vitamin C vs placebo). The military medical records were searched to determine whether the participants had a common cold. Multiple logistic regression analysis was performed to identify the association between vitamin C intake and diagnosis of common colds. In addition, subgroup analysis on the relationship between vitamin C intake and common cold according to smoking status, training camp and physical rank was conducted.

RESULTS

A total of 1444 participants were included in our study. Of these participants, 695 received vitamin C (6000 mg/day, vitamin C group), while 749 participants received placebo (0 mg/day, placebo group). The vitamin C group had a 0.80-fold lower risk of getting a common cold than did the placebo group. Subgroup analyses showed that this effect was stronger among subjects in camp A, among never smokers and among those in physical rank 3.

CONCLUSION

Vitamin C intake provides evidence to suggest that reducing the common colds in Korean Army soldiers. Our results may serve as a basis for introducing military healthcare policies that can provide vitamin C supplementation for military personnel in basic military training.

Racial Differences in the Association Between Luminal Master Regulator Gene Expression Levels and Breast Cancer Survival

PURPOSE

Compared with their European American (EA) counterparts, African American (AA) women are more likely to die from breast cancer in the United States. This disparity is greatest in hormone receptor-positive subtypes. Here we uncover biological factors underlying this disparity by comparing functional expression and prognostic significance of master transcriptional regulators of luminal differentiation.

EXPERIMENTAL DESIGN

Data and biospecimens from 262 AA and 293 EA patients diagnosed with breast cancer from 2001 to 2010 at a major medical center were analyzed by IHC for functional biomarkers of luminal differentiation, including estrogen receptor (ESR1) and its pioneer factors, FOXA1 and GATA3. Integrated comparison of protein levels with network-level gene expression analysis uncovered predictive correlations with race and survival.

RESULTS

Univariate or multivariate HRs for overall survival, estimated from digital IHC scoring of nuclear antigen, show distinct differences in the magnitude and significance of these biomarkers to predict survival based on race: ESR1 [EA HR = 0.47; 95% confidence interval (CI), 0.31-0.72 and AA HR = 0.77; 95% CI, 0.48-1.18]; FOXA1 (EA HR = 0.38; 95% CI, 0.23-0.63 and AA HR = 0.53; 95% CI, 0.31-0.88), and GATA3 (EA HR = 0.36; 95% CI, 0.23-0.56; AA HR = 0.57; CI, 0.56-1.4). In addition, we identify genes in the downstream regulons of these biomarkers highly correlated with race and survival.

CONCLUSIONS

Even within clinically homogeneous tumor groups, regulatory networks that drive mammary luminal differentiation reveal race-specific differences in their association with clinical outcome. Understanding these biomarkers and their downstream regulons will elucidate the intrinsic mechanisms that drive racial disparities in breast cancer survival.

Epigenetic re-wiring of breast cancer by pharmacological targeting of C-terminal binding protein

The C-terminal binding protein (CtBP) is an NADH-dependent dimeric family of nuclear proteins that scaffold interactions between transcriptional regulators and chromatin-modifying complexes. Its association with poor survival in several cancers implicates CtBP as a promising target for pharmacological intervention. We employed computer-assisted drug design to search for CtBP inhibitors, using quantitative structure-activity relationship (QSAR) modeling and docking. Functional screening of these drugs identified 4 compounds with low toxicity and high water solubility. Micro molar concentrations of these CtBP inhibitors produces significant de-repression of epigenetically silenced pro-epithelial genes, preferentially in the triple-negative breast cancer cell line MDA-MB-231. This epigenetic reprogramming occurs through eviction of CtBP from gene promoters; disrupted recruitment of chromatin-modifying protein complexes containing LSD1, and HDAC1; and re-wiring of activating histone marks at targeted genes. In functional assays, CtBP inhibition disrupts CtBP dimerization, decreases cell migration, abolishes cellular invasion, and improves DNA repair. Combinatorial use of CtBP inhibitors with the LSD1 inhibitor pargyline has synergistic influence. Finally, integrated correlation of gene expression in breast cancer patients with nuclear levels of CtBP1 and LSD1, reveals new potential therapeutic vulnerabilities. These findings implicate a broad role for this class of compounds in strategies for epigenetically targeted therapeutic intervention.

Abstract 5220: Transcription regulatory networks associated with luminal master regulator expression and breast cancer survival

The disparity in breast cancer burden of African Americans compared with European Americans is one of the most revealing instances in oncology associated with ethnicity. Recent studies demonstrated that there were highly intratumoral genetic heterogeneity and increased the frequency of basal subtypes among African Americans than European Americans. Because significant race-based disparities in breast cancer patients with hormone-receptor positive still persistent even after reflecting socio-economic status, there may be substantial roles playing by intrinsic biological factors contributing to the disparities. Transcriptional regulation governed by estrogen receptor plays critical roles in major changes in chromatin landscape that facilitate the assembly of other transcriptional complexes affecting mammary tumor initiation and proliferation. We investigated the estrogen receptor and its essential pioneer transcription factors how their expressions are associated with racial disparity with their prognostic significance. Co-expression analysis of estrogen receptor and its pioneer transcription factors suggest that ER-positive patients of women of European ancestry show much more favorable survival than women of African ancestry. Differential comparison of protein expression integrated with network-level gene expression analysis reveals significant differences in the predictive ability of the luminal master regulators based on race and survival. Moreover, we identified genes in the downstream of these master regulators that are highly correlated with race and survival. The comparative analysis of the predictive value of race-based cutoffs suggests that these master regulators of luminal differentiation have reduced transcriptional activity in the downstream regulatory network pathways in African ancestry. Functional characterization of the luminal master regulators and their downstream pathways may provide a better understanding of the intrinsic mechanisms that drive racial disparities in breast cancer survival.

Citation Format: Jung S. Byun, Sandeep Singhal, Samson Park, Dae IK Yi, Ambar Caban, Nasreen Vohra, Eliseo J. Perez-Stable, Anna Napoles, Kevin L. Gardner. Transcription regulatory networks associated with luminal master regulator expression and breast cancer survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5220.

Abstract 740: Mutational landscape of early-onset colorectal cancer tumors in Hispanics

Background: Colorectal cancer (CRC) is the 3rd and 1st leading cause of cancer-related deaths in men and women in the US and Puerto Rico, respectively. Although the incidence of CRC has been decreasing, annual CRC incidence rates have increased by more than 1.5% per year for more than a decade among patients 20 to 49 years old. Early-onset CRC represents a clinically distinct form of CRC often associated with a poor prognosis, which currently comprises 10% to 18% of newly diagnosed cases. Moreover, a marked increase in early-onset CRC incidence has been reported among Hispanics, compared to other racial/ethnic groups. The aim of this study was to perform whole exome sequencing analysis on sporadic, early-onset colorectal tumors and concordant healthy colonic mucosa in order to identify genetic variations that could contribute to the development of colorectal tumors at a younger age among Hispanics.

Methods: Whole exome sequencing analyses were performed on 42 concordant colorectal adenocarcinoma and colonic mucosa tissue samples from individuals diagnosed with colorectal cancer at &lt;50 years old to identify somatic and germinal mutations associated with early-onset colorectal cancer. All participants were recruited by PuertoRico Familial Colorectal Cancer Registry (PURIFICAR); only participants without known mutations in genes associated with hereditary cancer syndromes were included.

Results: A total of 14 shared somatic tumor-specific point mutations were detected in 16 of the 42 early-onset colorectal tumors analyzed. Six of these variants were located in introns and one was located in an intergenic region. When analyzing normal colonic mucosa, 26,716 shared point mutations were detected in all of the participants in our study. Of these, genetic variations were located in introns (16,443), exons (4,008), non-coding RNAs (3,516), promoters (3,467), intergenic regions (2,774), 3’ UTR (1,741), 5’ UTR (717), and splice sites (79).

Conclusion: This is the first description of the mutational landscape of early-onset colorectal tumors among Puerto Rican Hispanics, a Hispanic subgroup with a high burden of early-onset CRC. The majority of the mutations detected were not located in exons, suggesting that variations in genomic regions that regulate gene expression may contribute to early-onset carcinogenesis. Additional research is warranted to gain a more comprehensive understanding of the biology of sporadic, early-onset CRC in order to directly address this emerging public health problem and to subsequently shift current clinical practices for young patients across the cancer continuum, from prevention strategies to screening and/or treatment.

Citation Format: Maria Gonzalez-Pons, Lenis Rovira, Kelvin Carrasquillo, Ingrid Montes, Julyann Perez-Mayoral, Abiel Roche, Anna M. Napoles, Jung S. Byun, Eliseo Pérez-Stable, Kevin L. Gardner, Marcia Cruz-Correa. Mutational landscape of early-onset colorectal cancer tumors in Hispanics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 740.

Linking Race, Cancer Outcomes, and Tissue Repair

The burden of cancer in the United States is unevenly spread across its different populations, with stark differences in both disease prevalence and outcome on the basis of race and ethnicity. Although a large portion of these differences can be explained by a variety of sociobehavioral and socioeconomic factors, even after these exposures are taken into consideration, considerable disparities persist. In this review, we explore a conceptual framework of biological theories and unifying concepts, based on an evolutionary perspective, that may help better define common guiding principles for exploration of underlying causes of cancer health disparities. The ultimate goal of this conceptual perspective is to outline approaches that may aid in establishing integrated pathway and processes analyses to provide useful insights to guide the development of future interventions. These interventions will improve outcome, increase prevention, and ultimately eliminate all disparities.

Kaiso is highly expressed in TNBC tissues of women of African ancestry compared to Caucasian women

Purpose

Triple-negative breast cancer (TNBC) is most prevalent in young women of African ancestry (WAA) compared to women of other ethnicities. Recent studies found a correlation between high expression of the transcription factor Kaiso, TNBC aggressiveness, and ethnicity. However, little is known about Kaiso expression and localization patterns in TNBC tissues of WAA. Herein, we analyze Kaiso expression patterns in TNBC tissues of African (Nigerian), Caribbean (Barbados), African American (AA), and Caucasian American (CA) women.

Methods

Formalin-fixed and paraffin embedded (FFPE) TNBC tissue blocks from Nigeria and Barbados were utilized to construct a Nigerian/Barbadian tissue microarray (NB-TMA). This NB-TMA and a commercially available TMA comprising AA and CA TNBC tissues (AA-CA-YTMA) were subjected to immunohistochemistry to assess Kaiso expression and subcellular localization patterns, and correlate Kaiso expression with TNBC clinical features.

Results

Nigerian and Barbadian women in our study were diagnosed with TNBC at a younger age than AA and CA women. Nuclear and cytoplasmic Kaiso expression was observed in all tissues analyzed. Analysis of Kaiso expression in the NB-TMA and AA-CA-YTMA revealed that nuclear Kaiso H scores were significantly higher in Nigerian, Barbadian, and AA women compared with CA women. However, there was no statistically significant difference in nuclear Kaiso expression between Nigerian versus Barbadian women, or Barbadian versus AA women.

Conclusions

High levels of nuclear Kaiso expression were detected in patients with a higher degree of African heritage compared to their Caucasian counterparts, suggesting a role for Kaiso in TNBC racial disparity.

Electronic supplementary material

The online version of this article (doi:10.1007/s10552-017-0955-2) contains supplementary material, which is available to authorized users.

Abstract 1156: Epigenetic re-wiring of breast cancer by pharmacological targeting of C-terminal binding protein

The C-terminal binding protein (CtBP) is a family of dimeric nuclear proteins whose levels are increased in cancers of the colon, ovaries, prostate and breast. Elevated CtBP expression is associated with poor cancer survival and can also distinguish those node negative breast cancer patients who will show worse survival. This implicates CtBP as both a biomarker and a promising candidate for therapeutic intervention. As a dimer, CtBP provides a scaffold that couples multiple different DNA-binding transcriptional regulators with a variety of chromatin modifying protein complexes to alter the epigenetic landscape throughout the nucleus. These properties provide the rationale for pharmacological targeting of CtBP to change epigenetically regulated gene expression in cancer cells. In this study, we employ computer assisted drug design to screen for optimal quantitative structure-activity relationships (QSARs) between small molecules and CtBP to identify 24 potential CtBP inhibitors. Functional screening of these compounds identifies 4 lead compounds with low toxicity and high water solubility. Treatment of breast cancer cells at micro-molar concentrations of these small molecular inhibitors induces significant de-repression of epigenetically silenced pro-epithelial genes in the mesenchymal, triple negative breast cancer cell line, MDA-MB-231. This re-activation is associated with eviction of CtBP from the respective gene promoters, disrupted recruitment of CtBP-chromatin modifying protein complexes, increased deposition of activating epigenetic histone marks, and upregulation of both pro-epithelial gene mRNA and protein expression. In functional assays, CtBP inhibition by these small molecular inhibitors decreases cellular invasion, and improves DNA repair. FRET (Förster resonance energy transfer) analysis demonstrates that CTBP inhibition results in decreased FRET intensity, suggesting that CTBP dimerization is repressed by CTBP inhibition. In addition, pharmacological inhibition of CtBP combines with established epigenetically targeted drugs to synergistically decrease cell migration and potentiate the reactivation of silenced pro-epithelial gene expression in triple negative cancer cells. Finally, CTBP inhibition results in transcriptional repression of MDR1 expression and reduces the population of Doxorubicin resistant cells in the triple negative breast cancer cell lines. These findings implicate the possible use of this class of compounds in strategies for therapeutic intervention that may increase the efficacy and decrease the acquired resistance to targeted therapeutic intervention in breast cancer.

Citation Format: Jung S. Byun, Samson Park, Dae IK Yi, Mohamed Kabbout, Genqing Liang, Kevin L. Gardner. Epigenetic re-wiring of breast cancer by pharmacological targeting of C-terminal binding protein [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1156. doi:10.1158/1538-7445.AM2017-1156

A probiotic combination attenuates experimental colitis through inhibition of innate cytokine production

Inflammatory bowel disease (IBD) is a severe immune cell-mediated syndrome characterised by extensive inflammatory and effector mucosal responses leading to tissue destruction in the colon and small intestine. The leading hypothesis is that dysbiosis of the gut flora causes an excessive immune response and inflammation in the gastrointestinal track. Lactic acid bacteria (LAB) can correct dysbiosis of the normal microbiota. In the current study, the therapeutic potential of seven LAB strains in combination to treat IBD was evaluated using experimental colitis model. This LAB cocktail, designated GI7, includes four strains of Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Lactococcus lactis, two strains of Bifidobacterium bifidum, Bifidobacterium breve, and one strain of Streptococcus thermophilus. We confirmed that GI7 suppressed pro-inflammatory cytokines in Raw264.7 macrophages. When dextran sulphate sodium-induced colitic mice were treated with GI7, their symptoms of colitis, as assessed by body weight, colon length, myeloperoxidase activity, intestinal bleeding, and histological damage, were reduced compared to untreated mice. In addition, GI7 treatment significantly inhibited the production of innate pro-inflammatory cytokines during colitic progression. Therefore, we suggest that GI7, a combination of seven LAB, has a potential role in the treatment of IBD.

Effects of warm acupuncture on breast cancer-related chronic lymphedema: a randomized controlled trial

BACKGROUND

Effective treatment for breast cancer-related chronic lymphedema (bcrl) remains a clinical challenge. Acupuncture and moxibustion treatments have been shown to be beneficial and safe for treating bcrl. In the present randomized controlled trial, we compared the effectiveness of combined acupuncture and moxibustion ("warm acupuncture") with that of diosmin in bcrl.

METHODS

Breast cancer patients who met the inclusion and exclusion criteria (n = 30) were randomized to experimental and control groups (15 per group). On alternate days, patients in the experimental group received 30 minutes of acupuncture at 6 acupoints, with 3 of the needles each being topped by a 3-cm moxa stick. The control treatment was diosmin 900 mg 3 times daily. The control and experimental treatments were administered for 30 days. Outcome measures included arm circumferences (index of effectiveness), range of motion [rom (shoulder joint function)], quality of life, clinical safety, and adverse events.

RESULTS

Measured by the index of effectiveness, bcrl improved by 51.46% in the experimental group and by 26.27% in the control group (p < 0.00001). Effects were greatest at 10 cm above the elbow and at the wrist, where the warm needling was provided. Impairments in shoulder joint rom were minimal at baseline in both treatment groups. However, the roms of rear protraction, abduction, intorsion, and extorsion in the experimental group improved significantly; they did not change in the control group. Self-reported quality of life was significantly better with warm acupuncture than with diosmin. No adverse effects were reported during the treatment period, and laboratory examinations for clinical safety fell within the normal ranges.

CONCLUSIONS

Compared with diosmin, warm acupuncture treatment can effectively reduce the degree of bcrl at the specific acupoints treated and can promote quality of life. Warm acupuncture showed good clinical safety, without any adverse effects on blood or the cardiovascular system.

The Tax oncogene enhances ELL incorporation into p300 and P-TEFb containing protein complexes to activate transcription

The eleven-nineteen lysine-rich leukemia protein (ELL) is a key regulator of RNA polymerase II mediated transcription. ELL facilitates RNA polymerase II transcription pause site entry and release by dynamically interacting with p300 and the positive transcription elongation factor b (P-TEFb). In this study, we investigated the role of ELL during the HTLV-1 Tax oncogene induced transactivation. We show that ectopic expression of Tax enhances ELL incorporation into p300 and P-TEFb containing transcriptional complexes and the subsequent recruitment of these complexes to target genes in vivo. Depletion of ELL abrogates Tax induced transactivation of the immediate early genes Fos, Egr2 and NF-kB, suggesting that ELL is an essential cellular cofactor of the Tax oncogene. Thus, our study identifies a novel mechanism of ELL-dependent transactivation of immediate early genes by Tax and provides the rational for further defining the genome-wide targets of Tax and ELL.

The cortical contrast accumulation from brain computed tomography after endovascular treatment predicts symptomatic hemorrhage

BACKGROUND AND PURPOSE

The prognostic value of contrast accumulation from non-contrast brain computed tomography taken immediately after endovascular reperfusion treatment in acute ischaemic stroke patients to predict symptomatic hemorrhage was studied.

METHODS

Between July 2007 and August 2014, acute anterior circulation ischaemic stroke patients who were treated by intra-arterial thrombolysis or thrombectomy were included. Contrast accumulation was defined as a high attenuation area from non-contrast brain computed tomography immediately taken after endovascular reperfusion treatment, and patients were categorized into three groups according to the presence and location of contrast: (i) negative, (ii) cortical involvement and (iii) non-cortical involvement. The rates of symptomatic hemorrhage after 24 h and functional outcome at discharge were compared between patients with and without cortical involvement.

RESULTS

Of 64 patients who were treated by endovascular intervention, contrast accumulation was detected in 56, including 33 patients with cortical involvement and 23 patients without cortical involvement. The cortical involvement pattern was more frequently associated with symptomatic hemorrhage (13 vs. 1 patient, P = 0.003) and with grave outcome at discharge with modified Rankin Scale 5 or 6 (14 vs. 4, P = 0.048) than the non-cortical involvement group. Multivariate logistic regression analysis including initial collateral status and occlusion site disclosed that cortical involvement pattern independently predicted symptomatic hemorrhage after endovascular treatment (odds ratio 19.0, confidence interval 1.6-227.6, P = 0.020).

CONCLUSION

Our study provides evidence that the cortical involvement of contrast accumulation is associated with symptomatic hemorrhage after endovascular reperfusion treatment.

Promoter-bound p300 complexes facilitate post-mitotic transmission of transcriptional memory

A central hallmark of epigenetic inheritance is the parental transmission of changes in patterns of gene expression to progeny without modification of DNA sequence. Although, the trans-generational conveyance of this molecular memory has been traditionally linked to covalent modification of histone and/or DNA, recent studies suggest a role for proteins that persist or remain bound within chromatin to "bookmark" specific loci for enhanced or potentiated responses in daughter cells immediately following cell division. In this report we describe a role for p300 in enabling gene bookmarking by pre-initiation complexes (PICs) containing RNA polymerase II (pol II), Mediator and TBP. Once formed these complexes require p300 to enable reacquisition of protein complex assemblies, chromatin modifications and long range chromatin interactions that facilitate post-mitotic transmission of transcriptional memory of prior environmental stimuli.

Abstract 5576: Pharmacologic targeting of CtBP by established and newly designed inhibitors

Breast cancer is not one single entity but a collection of multiple diseases that affect different populations with varying incidence, morbidity and mortality. Thus finding a unified marker and associated biological processes that provide an overall indication of prognosis with clear insights into therapy opportunities is critically needed. Previous our studies showed that CtBP drives invasion and metastasis by governing a mode of gene regulation that is not only reversible and strongly influenced by environmental factors, like metabolic status, but can be stably passed on to expanding clones of tumor cells. Recent studies indicate that this form of “epigenetic regulation” plays a critical role in tumor progression. Our most recent finding that CtBP expression can function as a single predictor of overall poor survival from breast cancer, independent of current criteria such as hormone receptor status, suggests that inhibiting CtBP and the pathways it controls may provide a unifying concept for improving breast cancer diagnosis and treatment.

Using Computer Assisted Drug Design (CADD), we have identified multiple potential CtBP inhibitors from a panel of library of commercially available compounds. To validate the efficacy of these inhibitors, we have used targeted assessment by quantitative gene expression and ChIP analysis of established CtBP targets. We then scored compounds that disrupt CtBP controlled processes including EMT and genome instability at a low micromolar range. We found that some compounds were able to displace CtBP from endogenous genes and reactivate repressed gene expression. A smaller subset of these was able to inhibit cellular reprogramming associated with EMT and the wound healing response.

These findings suggest that CtBP may be an effective target of pharmacological inhibition to impair tumor invasion and metastasis, and offers a proof-of-principle that will provide a foundation for more effective treatment strategies against aggressive forms of breast cancer.

Citation Format: Jung S. Byun, Kevin L. Gardner. Pharmacologic targeting of CtBP by established and newly designed inhibitors. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5576. doi:10.1158/1538-7445.AM2013-5576

The histone acetyltransferase MOF is a key regulator of the embryonic stem cell core transcriptional network

Pluripotent embryonic stem cells (ESCs) maintain self-renewal and the potential for rapid response to differentiation cues. Both ESC features are subject to epigenetic regulation. Here we show that the histone acetyltransferase Mof plays an essential role in the maintenance of ESC self-renewal and pluripotency. ESCs with Mof deletion lose characteristic morphology, alkaline phosphatase (AP) staining, and differentiation potential. They also have aberrant expression of the core transcription factors Nanog, Oct4, and Sox2. Importantly, the phenotypes of Mof null ESCs can be partially suppressed by Nanog overexpression, supporting the idea that Mof functions as an upstream regulator of Nanog in ESCs. Genome-wide ChIP-sequencing and transcriptome analyses further demonstrate that Mof is an integral component of the ESC core transcriptional network and that Mof primes genes for diverse developmental programs. Mof is also required for Wdr5 recruitment and H3K4 methylation at key regulatory loci, highlighting the complexity and interconnectivity of various chromatin regulators in ESCs.

Abstract 5019: Reprogramming the cancer epigenome by “metabolic transduction”

This study focuses on the key concept of “metabolic transduction” as an important general mediator of cellular reprogramming in epithelial cancers. As a result of multiple studies on epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition in diverse epithelial cancers, the role of developmental plasticity during epithelial differentiation has emerged as a new area of research. Recent data from our lab suggest that metabolites and intermediates in cellular metabolism can act as secondary messengers to dynamically change and globally reprogram epigenetic signatures during normal development, tissue repair, and cancer. We refer to this process as metabolic transduction. Central to this concept is the role played by the C-terminal binding proteins, CTBP1 and CTBP2. Dimeric combination of these factors act as metabolic sensors that function, in the presence of the high energy intermediate NADH, to target multiple classes of chromatin modifying factors, including histone deacetylase, histone methyl-transferases, histone demethylases, DNA methyl-transferases to specific locales throughout the genome. Therefore, CTBP has the potential to mediate widespread changes in the epigenetic landscape and influence broad programs of cellular behavior. Genome-wide profiling studies by ChIP-seq reveal that CTBP controls a network of genes linked to cellular events that influence cellular re-programing or “plasticity” including stem cell transcriptional programs, angiogenesis, and EMT. These studies combined with immuno-histochemical profiling of patient samples indicates that CTBP plays an important role in driving progression of more aggressive forms of breast cancer including Triple Negative Breast Cancer and the basal-like subtypes. Recent studies in our group suggest a role for CTBP in enabling plasticity of cellular fate in malignant cells. Breast cancer cell lines capable of spontaneous de-differentiation into side populations with tumor initiation cell characteristic, such as Sum149PT, are highly enriched in CTBP and are dominated by CTBP controlled pathways. This association has significance in diverse types of cancer, since other transformed cell lines capable of spontaneous de-differentiation into side population, including the endometrial carcinoma cell line HEC-1A, show similar enrichment and dependency on CTBP. These striking similarities suggest that CTBP may represent a driver of a tumor cell plasticity, implicating this tumor cell feature as a new hallmark of epithelial cancers. Therefore, strategies to target CTBP, and cellular reprogramming in general, may provide new opportunities for therapeutic intervention.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5019. doi:1538-7445.AM2012-5019

The dual lives of bidirectional promoters

The sequencing of the human genome led to many insights into gene organization and structure. One interesting observation was the high frequency of bidirectional promoters characterized by two protein encoding genes whose promoters are arranged in a divergent or "head-to-head" configuration with less than 2000 base pairs of intervening sequence. Computational estimates published by various groups indicate that nearly 10% of the coding gene promoters are arranged in such a manner and the extent of this bias is a unique feature of mammalian genomes. Moreover, as a class, head-to-head promoters appear to be enriched in specific categories of gene function. Here we review the structure, composition, genomic properties and functional classifications of genes controlled by bidirectional promoters and explore the biological implication of these features. This article is part of a Special Issue entitled: Chromatin in time and space.

Abstract B41: Molecular linkages between metabolic imbalance, genome stability, and triple-negative breast cancer

Breast cancer remains a worldwide threat to public health with over one million new cases, and nearly half a million deaths each year. Defining the mechanisms underlying the causes and risks of breast cancer remains a major challenge to global health. Though numerous population-based studies have demonstrated a indisputable link between obesity and breast cancer, the underlying molecular mechanisms and their association with elevated circulating hormones and inflammatory cytokines remain poorly defined. Similarly, the reasons why young women of African descent show a nearly two fold higher frequency of the more aggressive forms of breast cancer including the Triple Negative and basal-like phenotypes, are not understood. Recently we have defined a role for the transcriptional repressor protein CtBP in the control of proteins important for DNA repair including the early onset breast cancer gene BRCA1. In response to elevated levels of the high energy metabolic intermediate, NADH (nicotinamide adenine dinucleotide), nuclear levels of CtBP are stabilized and target a transcriptional program that impairs DNA repair in breast cancer cells. Loss of CtBP or growth under calorie restricted conditions increases the ability of breast cancer cells to repair DNA damage. Genome-wide location analysis by chromatin immuno-precipitation combined with deep sequencing (ChIP-Seq) reveals that CtBP targets gene classes that play a significant role in epithelial-to-mesenchymal transition, genome stability and stem cell transcriptional programs. Moreover, by Kaplan-Meier survival analysis of several published gene expression studies, CtBP targeted gene lists distinguish breast cancer patients with worst outcome/survival. Finally, profiling of CtBP protein expression in tissue micro-array studies of breast cancer in African American and Nigerian populations demonstrates elevated levels of CtBP expression in patients with more aggressive disease phenotypes. We explore the role of CtBP and its gene regulatory network (the “CtBP Web”) in the population-based association of breast cancer with obesity and racial/ethnic groups at higher risk for triple negative breast cancer.

Citation Information: Cancer Epidemiol Biomarkers Prev 2011;20(10 Suppl):B41.

Analysis of 2D periodic nanostructures with an oxide overlayer via spectroscopic ellipsometry

The accurate nondestructive determination of the shapes or critical dimensions of periodic nanostructures is essential to the current integrated-circuits technology. Optical critical dimension (OCD) metrology is fast, nondestructive, and can be used in air, allows higher sampling rates compared to the non-optical methods such as scanning electron microscopy (SEM) or atomic-force microscopy (AFM), and does not damage the sample. The data are typically analyzed via rigorous coupled-wave analysis (RCWA), where the sample is modeled as a series of layers whose dimensional parameters are determined by a least-squares fit. The layers are typically approximated as a combination of core material and ambient. Oxide overlayers and surface roughness are common, however, and call into question two-phase approximation. In this study, a structure that is periodic in two dimensions and that is coated with a thin (3 nm) oxide was studied, and an extension of the RCWA method that allows structural information to be extracted from optical data even in the presence of oxide overlayers or surface roughness was developed.

Nondestructive analysis of coated periodic nanostructures from optical data

Optical data are essential for the accurate nondestructive determination of profiles of periodic structures in integrated-circuit technology. In rigorous coupled-wave analysis, the sample is generally modeled as layers consisting of a single material and the ambient. We extend present capabilities to the analysis of structures with overlayers and demonstrate our approach by determining quantitatively the thicknesses of top, sidewall, and bottom oxides of deliberately and naturally oxidized structures.

Transcriptional autoregulation by BRCA1

The BRCA1 gene product plays numerous roles in regulating genome integrity. Its role in assembling supermolecular complexes in response to DNA damage has been extensively studied; however, much less is understood about its role as a transcriptional coregulator. Loss or mutation is associated with hereditary breast and ovarian cancers, whereas altered expression occurs frequently in sporadic forms of breast cancer, suggesting that the control of BRCA1 transcription might be important to tumorigenesis. Here, we provide evidence of a striking linkage between the roles for BRCA1 as a transcriptional coregulator with control of its expression via an autoregulatory transcriptional loop. BRCA1 assembles with complexes containing E2F-1 and RB to form a repressive multicomponent transcriptional complex that inhibits BRCA1 promoter transcription. This complex is disrupted by genotoxic stress, resulting in the displacement of BRCA1 protein from the BRCA1 promoter and subsequent upregulation of BRCA1 transcription. Cells depleted of BRCA1 respond by upregulating BRCA1 transcripts, whereas cells overexpressing BRCA1 respond by downregulating BRCA1 transcripts. Tandem chromatin immmunoprecipitation studies show that BRCA1 is regulated by a dynamic coregulatory complex containing BRCA1, E2F1, and Rb at the BRCA1 promoter that is disrupted by DNA-damaging agents to increase its transcription. These results define a novel transcriptional mechanism of autoregulated homeostasis of BRCA1 that selectively titrates its levels to maintain genome integrity in response to genotoxic insult.

Combinatorial antileukemic disruption of oxidative homeostasis and mitochondrial stability by the redox reactive thalidomide 2-(2,4-difluoro-phenyl)-4,5,6,7-tetrafluoro-1H-isoindole-1,3(2H)-dione (CPS49) and flavopiridol

2-(2,4-Difluoro-phenyl)-4,5,6,7-tetrafluoro-1H-isoindole-1,3(2H)-dione (CPS49) is a member of a recently identified class of redox-reactive thalidomide analogs that show selective killing of leukemic cells by increasing intracellular reactive oxygen species (ROS) and targeting multiple transcriptional pathways. Flavopiridol is a semisynthetic flavonoid that inhibits cyclin-dependent kinases and also shows selective lethality against leukemic cells. The purpose of this study is to explore the efficacy and mechanism of action of the combinatorial use of the redox-reactive thalidomide CPS49 and the cyclin-dependent kinase inhibitor flavopiridol as a selective antileukemic therapeutic strategy. In combination, CPS49 and flavopiridol were found to induce selective cytotoxicity associated with mitochondrial dysfunction and elevations of ROS in leukemic cells ranging from additive to synergistic activity at low micromolar concentrations. Highest synergy was observed at the level of ROS generation with a strong correlation between cell-specific cytotoxicity and reciprocal coupling of drug-induced ROS elevation with glutathione depletion. Examination of the transcriptional targeting of CPS49 and flavopiridol combinations reveals that the drugs act in concert to initiate a cell specific transcriptional program that manipulates nuclear factor-kappaB (NF-kappaB), E2F-1, and p73 activity to promote enhanced mitochondrial instability by simultaneously elevating the expression of the proapoptotic factors BAX, BAD, p73, and PUMA while depressing expression of the antiapoptotic genes MCL1, XIAP, BCL-xL, SURVIVIN, and MDM2. The coadministration of CPS49 and flavopiridol acts through coordinate targeting of transcriptional pathways that enforce selective mitochondrial dysfunction and ROS elevation and is therefore a promising new therapeutic combination that warrants further preclinical exploration.

Expression of nitric oxide synthase isoforms in the testes of pigs

This study examined the expression of three isoforms of nitric oxide synthase (NOS) in the testes of pigs. Immunohistochemical studies demonstrated the presence of nNOS, eNOS and iNOS in interstitial cells, primary spermatocytes and spermatids. Positive immunoreactions for eNOS and iNOS were detected in peritubular myoid cells. Some vascular endothelial cells were positive for nNOS and eNOS. The expression of nitrotyrosine was detected in interstitial cells. In addition, the histochemical study revealed that all the interstitial cells were stained positively for NADPH-diaphorase, although some spermatids and vascular endothelial cells displayed moderate enzymatic activity. These findings suggest that three isoforms of NOS are expressed in the testis of pig and that they play important roles in the biology of interstitial cells that produce testosterone, as well as in spermatogenesis in the seminiferous tubules.

Singing, but not seizure, induces synaptotagmin IV in zebra finch song circuit nuclei

Synaptotagmins are a family of proteins that function in membrane fusion events, including synaptic vesicle exocytosis. Within this family, synaptotagmin IV (Syt IV) is unique in being a depolarization-induced immediate early gene (IEG). Experimental perturbation of Syt IV modulates neurotransmitter release in mice, flies, and PC12 cells, and modulates learning in mice. Despite these features, induction of Syt IV expression by a natural behavior has not been previously reported. We used the zebra finch, a songbird species, to investigate Syt IV because song is a naturally learned behavior whose neuroanatomical basis is largely identified. We observed that, similar to rodents, Syt IV is inducible in songbirds. This induction was selective and depended on the nature of neuronal depolarization. Generalized seizures caused by the GABA(A) receptor antagonist, metrazole, induced the IEG, ZENK, in zebra finch brain. However, these same seizures failed to induce Syt IV in song control areas. In contrast, when nontreated birds sang, three song control areas showed striking Syt IV induction. Further, this induction appeared sensitive to the social context in which song was sung. Together, these data suggest that neural activity during singing can drive Syt IV expression within song circuitry whereas generalized seizure activity fails to do so even though song control areas are depolarized. Our findings indicate that, within this neural circuit for a procedurally learned sensorimotor behavior, Syt IV is selective and requires precisely patterned neural activity and/or neuromodulation associated with singing.

Factors predicting concurrent cholangiocarcinomas associated with hepatolithiasis

BACKGROUND/AIMS

Hepatolithiasis is a risk factor for cholangiocarcinoma. However, it is difficult to detect early cholangiocarcinoma that occurs as a complication of hepatolithiasis. To identify the factors, which can be used for predicting cholangiocarcinomas in patients with hepatolithiasis, we compared the clinical characteristics of patients who had cholangiocarcinoma associated with hepatolithiasis with those of patients with hepatolithiasis only.

METHODOLOGY

Forty patients with cholangiocarcinoma associated with hepatolithiasis (group HC) and 73 patients with hepatolithiasis only (group H) were randomly selected for this study. Mean tumor size was 6.1 +/- 2.4 cm in diameter.

RESULTS

Patients of group HC were older (56.7 +/- 8.9 yr) than those of group H (49.2 +/- 12.9 yr) (p < 0.001). Weight loss was more frequent in group HC (51.5%) than in group H (5.5%) (p < 0.001) and serum alkaline phosphatase levels were higher in group HC (181 +/- 184 IU/L) than in group H (426 +/- 385 IU/L) (p < 0.001). The proportion of the patients who had hepatolithiasis in the right or both lobes of the liver was higher in group HC (72.5%) than in group H (50.6%) (p = 0.024). The optimal cutoff value of serum CEA level for cholangiocarcinoma detection was set at 4.2 ng/mL using ROC cure to give a sensitivity of 67.6% and a specificity of 90.5%. Group HC differed from group H because of its lower rates of both abdominal pain and cholangitis, longer duration of stone history, and lower serum albumin level. Factors that did not predict cholangiocarcinoma included sex ratio, white blood cell count, serum bilirubin level, and hepatic atrophy.

CONCLUSIONS

Cholangiocarcinoma should be suspected in patients with hepatolithiasis, especially when, the patient is over 40 years old, has a long history of hepatolithiasis with weight loss, a higher level of serum alkaline phosphatase, a lower level of serum albumin, a serum carcinoembryonic antigen level exceeding 4.2 ng/mL, and hepatolithiasis that is located either in the right or both lobes of the liver.

Second toe to index finger transfer

Between April 1994 and May 1998, 15 amputated index fingers were treated based on three classifications: group 1 consisted of patients with index finger defects immediately proximal to, yet including, the distal interphalangeal joint, group 2 were those patients with defects from the proximal part of the distal interphalangeal joint to the distal part of the proximal interphalangeal joint and group 3 comprised patients with more proximal defects than group 2. With a total of six men and nine women, seven cases were included in group 1, five in group 2 and three in group 3. For the patients in groups 1 and 2, only a partial length of the second toe was transferred to the index finger, whereas in group 3 the total length of the toe needed to be transferred. The results can be summarised as follows:1. The two-point discrimination of the reconstructed index tip was 2.2 mm for group 1, 2 mm for group 2 and 2.3 mm for group 3.2. In group 1, the average range of motion in the transferred toe was 43.8>> in the distal interphalangeal joint. In groups 2 and 3, the average range of motion in the transferred toe was 30>> and 30.7>> in the distal interphalangeal joint, and 50>> and 39.3>> in the proximal interphalangeal joint, respectively.3. When compared with the contralateral index finger, the pinching power was measured at 83% in group 1, 70% in group 2 and 60% in group 3.4. Excellent results were obtained in group 1, good results in group 2 and fair results in group 3. Accordingly, the more proximal the defect in the index finger, the less satisfactory the result obtained.

Replantation of avulsed scalps and secondary aesthetic correction

Five patients with avulsed scalps were treated with replantation between 1992 and 1998. All patients were women age 20 to 36 years. The percentage of the avulsed scalp ranged from 50% to 100% of the whole scalp. The vessels chosen for anastomosis were the superficial temporal artery, occipital artery, and superficial temporal vein. A vein graft harvested from the cephalic vein of the forearm was performed on the venous and arterial sides in 1 patient. Two patients experienced complete survival of the replanted scalp. Three patients showed 40%, 50%, and 80% survival areas, with the remaining defects resurfaced as split-thickness skin grafts. Six months later, the scar areas in the last 3 patients were reconstructed with an expansion of the normal or replanted scalp. The follow-up period ranged from 1 to 7 years. In 4 patients a partial return of sensation in the replanted scalp and motor function of the frontalis muscle were observed. All patients were satisfied with the aesthetic results of their surgery.

Dorsalis pedis tendocutaneous delayed arterialized venous flap in hand reconstruction

We report two patients whose acute soft-tissue and tendon defects in the hand were treated with a dorsalis pedis tendocutaneous delayed arterialized venous flap between 1994 and 1997. The surviving surface area was 100 percent in both patients. The flap sizes were 10 x 10 cm and 6 x 6 cm. At 2 weeks postoperatively, active flexion and passive extension commenced, and progressive resistance exercises were performed for an additional 5 weeks. Flaps showed a similar color match and skin texture compared with the normal skin of the hand. Advantages of the tendocutaneous delayed arterialized venous flap are that a larger flap can be obtained than when using a pure venous flap or arterialized venous flap; the survival rate of the arterialized venous flap increases, which permits the use of a composite flap; the main artery of the donor site is preserved; thin, nonbulky tissue is used; and elevation is easy, without deep dissection. The disadvantages are the two-stage operation, donor-site scarring, and weak extension of the toes.

The effects of oxygen radicals on the activity of nitric oxide synthase and guanylate cyclase

Reactive oxygen species such as superoxides, hydrogen peroxide (H2O2) and hydroxyl radicals have been suggested to be involved in the catalytic action of nitric oxide synthase (NOS) to produce NO from L-arginine. An examination was conducted on the effects of oxygen radical scavengers and oxygen radical-generating systems on the activity of neuronal NOS and guanylate cyclase (GC) in rat brains and NOS from the activated murine macrophage cell line J774. Catalase and superoxide dismutase (SOD) showed no significant effects on NOS or GC activity. Nitroblue tetrazolium (NBT, known as a superoxide radical scavenger) and peroxidase (POD) inhibited NOS, but their inhibitory actions were removed by increasing the concentration of arginine or NADPH respectively, in the reaction mixture. NOS and NO-dependent GC were inactivated by ascorbate/FeSO4 (a metal-catalyzed oxidation system), 2'2'-azobis-amidinopropane (a peroxy radical producer), and xanthine/xanthine oxidase (a superoxide generating system). The effects of oxygen radicals or antioxidants on the two isoforms of NOS were almost similar. However, H2O2 activated GC in a dose-dependent manner from 100 microM to 1 mM without significant effects on NOS. H2O2-induced GC activation was blocked by catalase. These results suggested that oxygen radicals inhibited NOS and GC, but H2O2 could activate GC directly.

Pharyngoesophageal reconstruction with a tubed free radial forearm flap

Various attempts at reconstruction of pharyngoesophageal defects after ablative surgery have been made to restore the function of the pharyngoesophagus. A tubed free radial forearm flap was used to reconstruct the pharyngoesophagus in 23 patients after resection of neoplasms from May 1989 to October 1995. Nineteen were males and four were females, the average patient age was 62.2 years. The follow-up ranged from 10 to 64 months (mean: 18 months). Oral intake within 3 weeks was possible in 18 patients (78 percent) The immediate postoperative complications were hematoma (n = 1), bleeding (n = 2), infection (n = 3), fistula (n = 4), and venous thrombosis (n = 1). A late complication was stricture of the lower anastomosing site (n = 3). The tubed free radial forearm flap has advantages over free jejunal transfer, including the larger caliber of the vascular pedicle, longer possible ischemic time, no laparotomy with less morbidity of the donor site, and better toleration of radiotherapy. Troublesome disadvantages include stricture and fistula formation at the suture sites. The authors modified the conventional free radial forearm flap to reduce complications. A small monitoring flap supplied by the septocutaneous branch of the radial artery was elevated to check the survival of the flap. During tubing, the vertical suture line was overlapped with a deepithelialized skin flap, and double layer sutures were done to prevent fistula. Two small triangular flaps were designed and inserted at the distal anastomotic site to prevent circular contracture. The outer-layer sutures were anchored to the surrounding rigid structure to withstand shrinkage and circular contraction. With this modification, the incidence of stricture and fistula formation was reduced to 13.0 percent and 17.4 percent, respectively, and these complications could be treated conservatively.

The effects of surgical and chemical delay procedures on the survival of arterialized venous flaps in rabbits

The aim of this study was to investigate the efficacy of a surgical delay procedure and a combined surgical and chemical delay procedure on the survival of arterialized venous flaps. Experimental groups included (1) a control group, (2) a surgical delay (4-day and 7-day delay) group, and (3) a combined surgical and chemical (doxazosin mesylate, nitroglycerine patch) delay group. These groups were further divided into subgroups (n = 10) depending on the delay period and the chemical agents. An arterialized venous flap was created on one ear of each rabbit. In the arterialized venous flap, arterial inflow was provided by anastomosis of the central auricular artery to the anterior branch of the central auricular vein and a venous outflow through the anterior marginal vein. In the control group, the arterialized venous flaps without any delay procedure showed complete necrosis of all flaps. In the surgical delay group, the mean percentage survival of arterialized venous flaps was 36.6 percent in the 4-day delay group and 59.7 percent in the 7-day delay group. In the combined surgical and chemical delay group, a 3-day chemical delay followed by a 4-day simultaneous surgical and chemical delay resulted in mean percentage survival of the arterialized venous flaps of 81.1 percent in the doxazosin mesylate group, 72.8 percent in the nitroglycerine patch group, and 92.9 percent in a combination group of doxazosin mesylate and nitroglycerine patch. A 3-day chemical delay followed by a 7-day simultaneous surgical and chemical delay resulted in mean percentage survival of the arterialized venous flaps of 94 percent in the doxazosin mesylate group, 90.2 percent in the nitroglycerine patch group, and 99 percent in a combination group of doxazosin mesylate and nitroglycerine patch. In conclusion, the surgical delay procedure increased the percentage survival of the arterialized venous flaps in proportion to the delay period. The combination group of surgical and chemical delay procedures had a significantly greater percentage survival than that of the surgical delay group (p < 0.001), and the delay period could be shortened.

Clinical applications of the delayed arterialized venous flap

Arterialized venous flaps have been used clinically but still have limited applications for coverage of small surface defects. Varying degrees of necrosis of the larger, arterialized venous flaps remain an unsolved problem. We have treated 13 patients, with acute soft-tissue defects in 9 patients and scar contracture in 4 patients, with surgically or surgically-chemically delayed arterialized venous flaps from 1993 to 1995. There were 9 males and 4 females. The average age of the 13 patients was 34.7 years. Donor sites were the medial calf in 4 patients, the volar surface of the forearm in 6 patients, the dorsum of the foot in 2 patients, and the medial thigh in 1 patient. Before arterialization, surgical delay was done in 9 patients and a combined surgical-chemical delay in 4 patients. There were 12 skin flaps and one composite tendocutaneous flap. The follow-up period ranged from 5 to 28 months, with an average of 15 months. The surviving surface area of the arterialized venous flap was 100% in 10 patients, axial 70% in 1 patient, axial 50% in 1 patient, and total necrosis in the remaining patient. Among the 10 flaps with total survival, the minimal flap size was 6 x 8 cm and the maximal flap size was 14 x 16 cm. Advantages of the delayed arterialized venous flap are (1) developing a larger flap than can be obtained with a pure venous flap or arterialized venous flap and (2) the increased survival rate of the arterialized venous flap, which permits the possibility of using a composite flap. This delayed arterialized venous flap also has all the advantages of the pure venous flap, such as preservation of the main artery of the donor site; thin, nonbulky tissue; and easy elevation without deep dissection. The disadvantage is the requirement of a two-stage operation.

Effects of delay procedures on vasculature and survival of arterialized venous flaps: an experimental study in rabbits

The effect of delay procedures on the survival of large arterialized venous flaps was studied in a rabbit ear model. Both ears of 25 New Zealand White rabbits (n = 50) were randomized into three operative groups receiving (1) no delay, (2) limited delay, or (3) extensive delay. Two weeks later the ear flap was completely divided, and arterialization of the flap venous tree was achieved by anastomosing the central artery of the ear to the anterior branch of the flap central vein. Survival area of 10 flaps in each group was assessed at 14 days. Flap vasculature was assessed in 10 additional ears in the nondelayed and extensively delayed groups by standardized vascular injections with radiopaque silicon rubber immediately, 6 hours, 24 hours, and 2 weeks after arterialization. Delay procedures significantly increased (p = 0.001, unpaired two-tailed Student's t test) survival of arterialized venous flaps in this model. Whereas all flaps in the non-delayed group underwent total necrosis, the mean viable surface area of the flaps was 67.9 percent in the limited delay group and 94.0 percent in the extensively delayed group. Lastly, angiographic studies suggest that delay procedures prior to arterialization of the venous tree enhance perfusion of the arterial tree by increasing venoarterial communications.

Results of one-stage penile reconstruction using an innervated radial osteocutaneous flap

Reconstruction of the penis may be indicated in cases of traumatic or surgical amputation of the penis, congenital absence of the penis, micropenis, male pseudohermaphroditism, or transsexualism. Despite recent advances in microsurgery, which have improved the results of total penile reconstructions to a great extent, this operation remains one of the biggest challenges to reconstructive plastic surgeons. The authors have performed one-stage penile reconstruction in five patients since 1989, using an innervated radial forearm osteocutaneous flap. At follow-up (up to 46 months), all patients showed aesthetically acceptable results and good sensory recovery. The most common complications were related to the urethra, involving two fistulae and one urethral stricture.