Erhan Bilal

Mitochondrial DNA Haplogroup D4a Is a Marker for Extreme Longevity in Japan

We report results from the analysis of complete mitochondrial DNA (mtDNA) sequences from 112 Japanese semi-supercentenarians (aged above 105 years) combined with previously published data from 96 patients in each of three non-disease phenotypes: centenarians (99–105 years of age), healthy non-obese males, obese young males and four disease phenotypes, diabetics with and without angiopathy, and Alzheimers and Parkinsons disease patients. We analyze the correlation between mitochondrial polymorphisms and the longevity phenotype using two different methods. We first use an exhaustive algorithm to identify all maximal patterns of polymorphisms shared by at least five individuals and define a significance score for enrichment of the patterns in each phenotype relative to healthy normals. Our study confirms the correlations observed in a previous study showing enrichment of a hierarchy of haplogroups in the D clade for longevity. For the extreme longevity phenotype we see a single statistically significant signal: a progressive enrichment of certain “beneficial” patterns in centenarians and semi-supercentenarians in the D4a haplogroup. We then use Principal Component Spectral Analysis of the SNP-SNP Covariance Matrix to compare the measured eigenvalues to a Null distribution of eigenvalues on Gaussian datasets to determine whether the correlations in the data (due to longevity) arises from some property of the mutations themselves or whether they are due to population structure. The conclusion is that the correlations are entirely due to population structure (phylogenetic tree). We find no signal for a functional mtDNA SNP correlated with longevity. The fact that the correlations are from the population structure suggests that hitch-hiking on autosomal events is a possible explanation for the observed correlations.

Enrichment of longevity phenotype in mtDNA haplogroups D4b2b, D4a, and D5 in the Japanese population

We report new results from the re-analysis of 672 complete mitochondrial (mtDNA) genomes of unrelated Japanese individuals stratified into seven equal sized groups by the phenotypes: diabetic patients, diabetic patients with severe angiopathy, healthy non-obese young males, obese young males, patients with Alzheimer’s disease, patients with Parkinson’s disease and centenarians. Each phenotype had 96 samples over 27 known haplogroups: A, B4a, B4b, B4c, B*, B5, D*, F1, F2, M*, M7a, M7b, M8, M9, D4a, D4b1, D4b2, D4d, D4e, D4g, D4h, D5, G, Z, M*, N9a, and N9b. A t-test comparing the fraction of samples in a haplogroup to healthy young males showed a significant enrichment of haplogroups D4a, D5, and D4b2 in centenarians. The D4b2 enrichment was limited to a subgroup of 40 of 61 samples which had the synonymous mutation 9296Cxa0>xa0T. We identified this cluster as a distinct haplogroup and labeled it as D4b2b. Using an exhaustive procedure, we constructed the complete list of “mutation patterns” for centenarians and showed that the most significant patterns were in D4a, D5, and D4b2b. We argue that if a selection for longevity appeared only once, it was probably an autosomal event which could be dated to after the appearance of the D mega-group but before the coalescent time of D4a, D5, and D4b2b. Using a simple procedure, we estimated that this event occurred 24.4xa0±xa00.9 kYBP.

Amplified Loci on Chromosomes 8 and 17 Predict Early Relapse in ER-Positive Breast Cancers

Adjuvant hormonal therapy is administered to all early stage ER+ breast cancers, and has led to significantly improved survival. Unfortunately, a subset of ER+ breast cancers suffer early relapse despite hormonal therapy. To identify molecular markers associated with early relapse in ER+ breast cancer, an outlier analysis method was applied to a published gene expression dataset of 268 ER+ early-stage breast cancers treated with tamoxifen alone. Increased expression of sets of genes that clustered in chromosomal locations consistent with the presence of amplicons at 8q24.3, 8p11.2, 17q12 (HER2 locus) and 17q21.33-q25.1 were each found to be independent markers for early disease recurrence. Distant metastasis free survival (DMFS) after 10 years for cases with any amplicon (DMFS u200a=u200a56.1%, 95% CI u200a=u200a48.3–63.9%) was significantly lower (P u200a=u200a0.0016) than cases without any of the amplicons (DMFS u200a=u200a87%, 95% CI u200a=u200a76.3% –97.7%). The association between presence of chromosomal amplifications in these regions and poor outcome in ER+ breast cancers was independent of histologic grade and was confirmed in independent clinical datasets. A separate validation using a FISH-based assay to detect the amplicons at 8q24.3, 8p11.2, and 17q21.33-q25.1 in a set of 36 early stage ER+/HER2- breast cancers treated with tamoxifen suggests that the presence of these amplicons are indeed predictive of early recurrence. We conclude that these amplicons may serve as prognostic markers of early relapse in ER+ breast cancer, and may identify novel therapeutic targets for poor prognosis ER+ breast cancers.

Identification of the YES1 Kinase as a Therapeutic Target in Basal-Like Breast Cancers

Normal cellular behavior can be described as a complex, regulated network of interaction between genes and proteins. Targeted cancer therapies aim to neutralize specific proteins that are necessary for the cancer cell to remain viable in vivo. Ideally, the proteins targeted should be such that their downregulation has a major impact on the survival/fitness of the tumor cells and, at the same time, has a smaller effect on normal cells. It is difficult to use standard analysis methods on gene or protein expression levels to identify these targets because the level thresholds for tumorigenic behavior are different for different genes/proteins. We have developed a novel methodology to identify therapeutic targets by using a new paradigm called gene centrality. The main idea is that, in addition to being overexpressed, good therapeutic targets should have a high degree of connectivity in the tumor network because one expects that suppression of its expression would affect many other genes. We propose a mathematical quantity called centrality, which measures the degree of connectivity of genes in a network in which each edge is weighted by the expression level of the target gene. Using our method, we found that several SRC proto-oncogenes LYN, YES1, HCK, FYN, and LCK have high centrality in identifiable subsets of basal-like and HER2+ breast cancers. To experimentally validate the clinical value of this finding, we evaluated the effect of YES1 knockdown in basal-like breast cancer cell lines that overexpress this gene. We found that YES1 downregulation has a significant effect on the survival of these cell lines. Our results identify YES1 as a target for therapeutics in a subset of basal-like breast cancers.

Metabotropic Glutamate Receptor 1 Expression and Its Polymorphic Variants Associate with Breast Cancer Phenotypes

Several epidemiological studies have suggested a link between melanoma and breast cancer. Metabotropic glutamate receptor 1 (GRM1), which is involved in many cellular processes including proliferation and differentiation, has been implicated in melanomagenesis, with ectopic expression of GRM1 causing malignant transformation of melanocytes. This study was undertaken to evaluate GRM1 expression and polymorphic variants in GRM1 for associations with breast cancer phenotypes. Three single nucleotide polymorphisms (SNPs) in GRM1 were evaluated for associations with breast cancer clinicopathologic variables. GRM1 expression was evaluated in human normal and cancerous breast tissue and for in vitro response to hormonal manipulation. Genotyping was performed on genomic DNA from over 1,000 breast cancer patients. Rs6923492 and rs362962 genotypes associated with age at diagnosis that was highly dependent upon the breast cancer molecular phenotype. The rs362962 TT genotype also associated with risk of estrogen receptor or progesterone receptor positive breast cancer. In vitro analysis showed increased GRM1 expression in breast cancer cells treated with estrogen or the combination of estrogen and progesterone, but reduced GRM1 expression with tamoxifen treatment. Evaluation of GRM1 expression in human breast tumor specimens demonstrated significant correlations between GRM1 staining with tissue type and molecular features. Furthermore, analysis of gene expression data from primary breast tumors showed that high GRM1 expression correlated with a shorter distant metastasis-free survival as compared to low GRM1 expression in tamoxifen-treated patients. Additionally, induced knockdown of GRM1 in an estrogen receptor positive breast cancer cell line correlated with reduced cell proliferation. Taken together, these findings suggest a functional role for GRM1 in breast cancer.

Elafin drives poor outcome in high-grade serous ovarian cancers and basal-like breast tumors.

High-grade serous ovarian carcinoma (HGSOC) and basal-like breast cancer (BLBC) share many features including TP53 mutations, genomic instability and poor prognosis. We recently reported that Elafin is overexpressed by HGSOC and is associated with poor overall survival. Here, we confirm that Elafin overexpression is associated with shorter survival in 1000 HGSOC patients. Elafin confers a proliferative advantage to tumor cells through the activation of the MAP kinase pathway. This mitogenic effect can be neutralized by RNA interference, specific antibodies and a MEK inhibitor. Elafin expression in patient-derived samples was also associated with chemoresistance and strongly correlates with bcl-xL expression. We extended these findings into the examination of 1100 primary breast tumors and six breast cancer cell lines. We observed that Elafin is overexpressed and secreted specifically by BLBC tumors and cell lines, leading to a similar mitogenic effect through activation of the MAP kinase pathway. Here too, Elafin overexpression is associated with poor overall survival, suggesting that it may serve as a biomarker and therapeutic target in this setting.

Abstract 81: Role of GRM1 in breast cancer

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, ILnnDespite epidemiologic studies suggesting a link between melanoma and breast cancer, molecular mechanisms leading to these associations have not been elucidated. Overexpression of metabotropic glutamate receptor 1 (GRM1) has been implicated in melanomagenesis. Its primary action occurs through activation of the MAPK signaling pathway and other pathways through intracellular calcium release. A recent study implicated GRM1 as playing a role in angiogenesis in hormone receptor negative breast cancer. However, the role of GRM1 in hormone receptor positive disease is yet to be described. Given the associations between melanoma and breast cancer, we evaluated three SNPs in GRM1 for genotype associations with breast cancer clinicopathologic variables using DNA isolated from peripheral blood of 1,096 breast cancer patients. Our study found that a SNP in GRM1 resulting in a proline to serine substitution correlates with age at diagnosis of breast cancer and reflects the receptor status of the breast cancer, e.g. for progesterone receptor positive (PR+) disease, proline carriers were diagnosed 8 years earlier than serine carriers. Genotype-specific associations with risk of developing specific molecular subtypes of breast cancer were observed, i.e. serine carriers were twice as likely to develop estrogen receptor positive (ER+) and PR+ disease. Furthermore, carrying the proline isoform also correlated with higher risk of recurrence of breast cancer and shorter time to recurrence. Immunohistochemical evaluation of breast microarrays showed that GRM1 expression is higher in breast cancers as compared to normal tissue and is higher in ER+ as compared to ER- breast cancers. This parallels higher expression observed in ER+ breast cancer cells lines in comparison to ER- lines. In vitro studies with breast cancer cell lines were also performed to evaluate the expression of GRM1 as a function of hormone exposure and cell line receptor status. Treatment of ER+ cell lines with estradiol resulted in increased GRM1, while tamoxifen decreased expression. Gene expression data on ER+ breast cancers treated with tamoxifen were reanalyzed for association between GRM1 expression and recurrence. Analysis of breast cancers treated with tamoxifen from an independent cohort demonstrated that high expressors of GRM1 have a worse distant recurrence free survival. The results of these studies implicate GRM1 in hormone receptor positive breast cancer biology. Additional knowledge regarding the interaction between GRM1 and hormone signaling could have significant implications in breast cancer risk, prevention, and treatment.nnCitation 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 81. doi:1538-7445.AM2012-81

Abstract B74: Elafin drives poor outcome in high-grade serous ovarian cancers and basal-like breast tumors

High grade serous ovarian carcinoma (HGSOC) and basal-like breast cancer (BLBC) share many features including TP53 mutations, genomic instability and poor prognosis. We recently reported that Elafin is overexpressed by HGSOC and is associated with poor overall survival. Here, we confirmed that Elafin overexpression is associated with shorter survival in 1000 HGSOC patients. Elafin confers a proliferative advantage to tumor cells through activation of the MAP kinase pathway. This mitogenic effect can be neutralized by RNA interference, specific antibodies, and a MEK inhibitor. Elafin expression in patient-derived samples was also associated with chemoresistance and strongly correlates with bcl-xL expression. We translated these findings into examination of 1100 primary breast tumors and 6 breast cancer cell lines. We observed that Elafin is overexpressed and secreted specifically by BLBC tumors and cell lines, leading to a similar mitogenic effect through activation of the MAP kinase pathway. Here too, Elafin overexpression is associated with shorter overall survival, suggesting that it may serve as a biomarker or therapeutic target in this setting.nnCitation Format: Intidhar Labidi-Galy, Adam Clauss, Vivian Ng, Sekhar Duraisamy, Kevin M. Elias, Erhan Bilal, Rachel A. Davidowitz, Yiling Lu, Gayane Badalian-Very, Hui-Ying Piao, Un-Beom Kang, Scott Ficarro, Shridar Ganesan, Gordon B. Mills, Jarrod Marto, Ronny Drapkin. Elafin drives poor outcome in high-grade serous ovarian cancers and basal-like breast tumors. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr B74.

Abstract C34: Amplified loci on chromosomes 8 and 17 predict Tamoxifen resistance in ER+ breast tumors

Most ER+ breast cancers are treated with anti‐estrogens like Tamoxifen which disrupt the Estrogen growth pathway. However, not all ER+ cases respond to this therapy. This study aims to identify genetic markers associated with increased sensitivity or resistance to Tamoxifen using outlier analysis. We collected 268 ER+ samples of gene expression data from three separate published studies on Tamoxifen treated patients with follow‐up information on distant metastasis‐free survival time. Genes were associated with Kaplan‐Meyer survival curves based on their outlier profile and filtered, using the long‐rank test, for differential survival distributions at p‐value Citation Information: Cancer Res 2009;69(23 Suppl):C34.

Abnormalities of 53BP1 in Basal-Like Breast Cancer.

Background: Abnormalities in the DNA repair mechanism have been proposed to play a central role in the development of breast cancers. However the specific mechanism underlying DNA repair defects in sporadic breast cancer are mostly unknown. As 53BP1 plays a critical role in DNA repair response and has been identified as a potential tumor suppressor, its expression in basal-like breast cancer cell lines and clinical samples was investigated.Experimental Design: mRNA expression of 53BP1 was investigated in publicly available gene expression data sets. Protein expression of 53BP1 was evaluated in a large set of clinically annotated breast cancer specimens by immunohistochemistry. Analysis of 53BP1 and related proteins was performed in a set of human and mouse breast cancer cell lines.Results: Gene expression analysis demonstrated that a subset of basal-like breast cancer had decreased expression of 53BP1. Analysis of over 400 breast cancers in a tissue microarray showed that loss of 53BP1 staining was almost exclusively found in tumors that lacked ER, PR and HER2 expression; this triple-negative phenotype is characteristic of BLC. Approximately 42% of triple-negative breast cancers have abnormally low levels of 53BP1, while Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1122.