Therapeutic vulnerabilities in triple negative breast cancer: Stem-like traits explored within molecular classification

Triple Negative Breast Cancer (TNBC) is the most aggressive type of breast cancer (BC). Despite advances in the clinical management of TNBC, recurrence-related mortality remains a challenge. The stem-like phenotype of TNBC plays a significant role in the persistence of minimal disease residue after therapy. Individuals exhibiting stem-like characteristics are particularly prone to inducing malignant relapse accompanied by strong resistance. Therefore, stem-like traits have been broadly proposed as therapeutic vulnerabilities to treat TNBC and reduce recurrence. However, heterogeneity within TNBC often generally restricts the stability of the therapeutic efficacy. To understand the heterogeneity and manage TNBC more precisely, multiple TNBC subtyping categories have been reported, providing the basis for profile-according therapeutic regimens. To provide more insight into targeting stem-like traits to ablate TNBC and reduce recurrence in the context of heterogeneity, this paper reviewed the molecular subtyping of TNBC, identified the consensus subtypes with distinct stem-like phenotypes, characterized the stemness hierarchy of TNBC, outlined the biological models for stem-like TNBC subtypes, summarized the therapeutic vulnerabilities in stem-like traits of the subtypes, and proposed potential therapeutic regimens targeting stem-like characteristics to improve TNBC prognosis.

Differential role of glucocorticoid receptor based on its cell type specific expression on tumor cells and infiltrating lymphocytes

BACKGROUND

The glucocorticoid receptor (GR) is frequently expressed in breast cancer (BC), and its prognostic implications are contingent on estrogen receptor (ER) status. To address conflicting reports and explore therapeutic potential, a GR signature (GRsig) independent of ER status was developed. We also investigated cell type-specific GR protein expression in BC tumor epithelial cells and infiltrating lymphocytes.

METHODS

GRsig was derived from Dexamethasone treated cell lines through a bioinformatic pipeline. Immunohistochemistry assessed GR protein expression. Associations between GRsig and tumor phenotypes (proliferation, cytolytic activity (CYT), immune cell distribution, and epithelial-to-mesenchymal transition (EMT) were explored in public datasets. Single-cell RNA sequencing data evaluated context-dependent GR roles, and a cell type-specific prognostic role was assessed in an independent BC cohort.

RESULTS

High GRsig levels were associated with a favorable prognosis across BC subtypes. Tumor-specific high GRsig correlated with lower proliferation, increased CYT, and anti-tumorigenic immune cells. Single-cell data analysis revealed higher GRsig expression in immune cells, negatively correlating with EMT while a positive correlation was observed with EMT primarily in tumor and stromal cells. Univariate and multivariate analyses demonstrated the robust and independent predictive capability of GRsig for favorable prognosis. GR protein expression on immune cells in triple-negative tumors indicated a favorable prognosis.

CONCLUSION

This study underscores the cell type-specific role of GR, where its expression on tumor cells is associated with aggressive features like EMT, while in infiltrating lymphocytes, it predicts a better prognosis, particularly within TNBC tumors. The GRsig emerges as a promising independent prognostic indicator across diverse BC subtypes.

BRCA1 expression, its correlation with clinicopathological features, and response to neoadjuvant chemotherapy in high-grade serous ovarian cancer

AIM

In high-grade serous ovarian cancers (HG-SOC), BRCA1 mutation is one of the predominant mutations reported by various studies. However, the non-mutational mechanisms of BRCA pathway inactivation in HG-SOC are unclear. We evaluated BRCA1 inactivation by estimating its expression with its repressor, ID4, in primary and neoadjuvant chemotherapy (NACT)-treated HG-SOC tumors with known therapeutic responses.

METHODS

We evaluated the expression pattern of BRCA1 protein by immunohistochemistry in 119 cases of HG-SOC from a hospital cohort consisting of primary (N = 69) and NACT-treated (N = 50) tumors. Histological patterns (SET), stromal infiltration by lymphocytes (sTILs), and chemotherapy response score (CRS) were estimated by microscopic examination. Gene expression levels of BRCA1, and its repressor ID4, were estimated by qPCR. The association of BRCA1 protein and mRNA with clinicopathological features was studied. The relevance of the BRCA1/ID4 ratio was evaluated in tumors with different CRS.

RESULTS

BRCA1 protein expression was observed in 12% of primary and 19% of NACT-treated HG-SOC tumors. We observed moderate concordance between BRCA1 protein and mRNA expression (AUC = 0.677). High BRCA1 mRNA expression was significantly associated with a more frequent SET pattern (p = 0.024), higher sTILs density (p = 0.042), and increased mitosis (p = 0.028). BRCA1-negative tumors showed higher expression of ID4 though not statistically significant. A higher BRCA1/ID4 ratio was associated with high sTILs density in primary (p = 0.042) and NACT-treated tumors (p = 0.040).

CONCLUSION

Our findings show the utility of the BRCA1/ID4 ratio in predicting neoadjuvant therapy response, which needs further evaluation in larger cohorts with long-term outcomes.

An androgen receptor regulated gene score is associated with epithelial to mesenchymal transition features in triple negative breast cancers

BACKGROUND

Androgen receptor (AR) is considered a marker of better prognosis in hormone receptor positive breast cancers (BC), however, its role in triple negative breast cancer (TNBC) is controversial. This may be attributed to intrinsic molecular differences or scoring methods for AR positivity. We derived AR regulated gene score and examined its utility in BC subtypes.

METHODS

AR regulated genes were derived by applying a bioinformatic pipeline on publicly available microarray data sets of AR+ BC cell lines and gene score was calculated as average expression of six AR regulated genes. Tumors were divided into AR high and low based on gene score and associations with clinical parameters, circulating androgens, survival and epithelial to mesenchymal transition (EMT) markers were examined, further evaluated in invitro models and public datasets.

RESULTS

53% (133/249) tumors were classified as AR gene score high and were associated with significantly better clinical parameters, disease-free survival (86.13 vs 72.69 months, log rank p = 0.032) when compared to AR low tumors. 36% of TNBC (N = 66) were AR gene score high with higher expression of EMT markers (p = 0.024) and had high intratumoral levels of 5α-reductase, enzyme involved in intracrine androgen metabolism. In MDA-MB-453 treated with dihydrotestosterone, SLUG expression increased, E-cadherin decreased with increase in migration and these changes were reversed with bicalutamide. Similar results were obtained in public datasets.

CONCLUSION

Deciphering the role of AR in BC is difficult based on AR protein levels alone. Our results support the context dependent function of AR in driving better prognosis in ER positive tumors and EMT features in TNBC tumors.

Multi-modal transcriptomic analysis unravels enrichment of hybrid epithelial/mesenchymal state and enhanced phenotypic heterogeneity in basal breast cancer

Intra-tumoral phenotypic heterogeneity promotes tumor relapse and therapeutic resistance and remains an unsolved clinical challenge. It manifests along multiple phenotypic axes and decoding the interconnections among these different axes is crucial to understand its molecular origins and to develop novel therapeutic strategies to control it. Here, we use multi-modal transcriptomic data analysis - bulk, single-cell and spatial transcriptomics - from breast cancer cell lines and primary tumor samples, to identify associations between epithelial-mesenchymal transition (EMT) and luminal-basal plasticity - two key processes that enable heterogeneity. We show that luminal breast cancer strongly associates with an epithelial cell state, but basal breast cancer is associated with hybrid epithelial/mesenchymal phenotype(s) and higher phenotypic heterogeneity. These patterns were inherent in methylation profiles, suggesting an epigenetic crosstalk between EMT and lineage plasticity in breast cancer. Mathematical modelling of core underlying gene regulatory networks representative of the crosstalk between the luminal-basal and epithelial-mesenchymal axes recapitulate and thus elucidate mechanistic underpinnings of the observed associations from transcriptomic data. Our systems-based approach integrating multi-modal data analysis with mechanism-based modeling offers a predictive framework to characterize intra-tumor heterogeneity and to identify possible interventions to restrict it.

PI3K/AKT/mTOR signaling transduction pathway and targeted therapies in cancer

The PI3K/AKT/mTOR (PAM) signaling pathway is a highly conserved signal transduction network in eukaryotic cells that promotes cell survival, cell growth, and cell cycle progression. Growth factor signalling to transcription factors in the PAM axis is highly regulated by multiple cross-interactions with several other signaling pathways, and dysregulation of signal transduction can predispose to cancer development. The PAM axis is the most frequently activated signaling pathway in human cancer and is often implicated in resistance to anticancer therapies. Dysfunction of components of this pathway such as hyperactivity of PI3K, loss of function of PTEN, and gain-of-function of AKT, are notorious drivers of treatment resistance and disease progression in cancer. In this review we highlight the major dysregulations in the PAM signaling pathway in cancer, and discuss the results of PI3K, AKT and mTOR inhibitors as monotherapy and in co-administation with other antineoplastic agents in clinical trials as a strategy for overcoming treatment resistance. Finally, the major mechanisms of resistance to PAM signaling targeted therapies, including PAM signaling in immunology and immunotherapies are also discussed.

Premenopausal women with breast cancer in the early post-partum period show molecular profiles of invasion and are associated with poor prognosis

PURPOSE

Young premenopausal women develop breast cancer (BC) within 5-10 years of the last childbirth, known as post-partum breast cancers (PPBC), often present with aggressive disease. The exact mechanisms that lead to poor prognosis in these patients are largely unknown.

METHODS

We have evaluated the association of clinical and reproductive factors with BC in a cohort of women ≤ 45 years (N = 155) with long-term follow-up. Based on duration since last childbirth (LCB), grouped patients into PPBC1 (LCB ≤ 5 years), PPBC2 (LCB between 6 and 10 years), PPBC3 (LCB > 10 years), and NPBC (age-matched nulliparous BC patients). We compared disease-free survival and hazard associated with recurrence/metastasis between the groups. RNA sequencing of tumor samples was performed from three parous groups (n = 10), and transcriptomic data were analyzed for differentially expressed genes and altered pathways.

RESULTS

Women in the PPBC1 group had an early menarche and late age at first and last childbirth compared to other groups. Survival analysis within lymph node-positive tumors showed that PPBC1 tumors had a worse prognosis than PPBC2 and NPBC tumors (p = 0.015 and p = 0.026, respectively). Clustering of the differentially expressed genes between the groups showed distinct expression in early PPBC (E-PPBC) tumors. Pathway analysis revealed upregulation of invasive-related pathways along with T cell exhaustion, extracellular matrix remodeling, angiogenesis, and epithelial-to-mesenchymal transition in E-PPBC tumors.

CONCLUSION

Early PPBC is a unique subtype with aggressive clinical features and distinct biology. Further research is needed to accurately project the risk of recurrence and optimal treatment strategies in these young patients.

The dynamic tumor-stromal crosstalk: implications of 'stromal-hot' tumors in the process of epithelial-mesenchymal transition in breast cancer

BACKGROUND

Breast cancer metastatic programming involves an intricate process by which the tumor cell coevolves with the surrounding extracellular niche. The supporting cells from the local host stroma get transformed into cancer-associated stromal cells. This complex crosstalk leads to extracellular matrix remodeling, invasion, and eventually distant metastasis.

METHODS

In this review, we examine the protein-miRNA secretome that is crucial for this crosstalk. We also provide evidence from the literature for the pivotal role played by the various stromal cells like fibroblasts, adipocytes, and immune cells in promoting the process of EMT in breast cancer. Through in-silico analysis, we have also attempted to establish that stromal presence is integral to the process of EMT.

RESULTS AND CONCLUSION

The in-silico analysis delineates the persuasive role of the stroma in mediating epithelial-to-mesenchymal transition. This review elucidates the importance of examining the role of the stromal niche that can yield promising diagnostic markers and pave avenues for formulating tailored anti-cancer therapy. Process of EMT as driven by 'stroma-hot' tumors: The process of EMT is driven by the stromal cells. The stromal cells in the form of  fibroblasts, adipocytes, endothelial cells, mesenchymal stromal cells and tissue associated macrophages secrete the miRNA-protein secretome that modulates the stromal niche and the tumor cells to be become 'tumor associated'. This drives tumor progression and invasion. The 'stromal-hot' tumors eventually get the benefit of the surplus nurturing from the stroma that facilitates EMT leading to distant organ seeding and metastasis.

A comparative analysis of clinicopathological features and survival between pre and postmenopausal breast cancer from an Indian cohort

Breast cancer (BC) among premenopausal women is an aggressive disease associated with poor outcome despite intensive treatment. Higher burden is observed in southeast Asian countries attributed to younger population structure. We compared the reproductive and clinicopathological characteristics, distribution of subtypes and survival between pre and postmenopausal women from a retrospective cohort of BC patients with median follow up over 6 years to examine the differences. In our cohort of 446 BC patients, 162/446 (36.3%) were premenopausal. Parity and age at last childbirth were significantly different between pre and postmenopausal women. Premenopausal BC had a higher proportion of HER2 amplified and triple negative breast cancer (TNBC) tumors (p = 0.012). Stratified analysis by molecular subtypes showed TNBC had significantly better disease free (DFS) and overall survival (OS) among premenopausal group (mean survival, pre vs. post, DFS = 79.2 vs. 54.0 months, OS = 72.5 vs. 49.5 months, p = 0.002 for both). Analysis on external datasets (SCAN-B, METABRIC) confirmed this finding for overall survival. Our data confirmed the previously observed association of clinical and pathological features between pre and postmenopausal BC. Exploration of better survival among premenopausal TNBC tumors is warranted in larger cohorts with long term follow up.

Abstract P2-19-02: Androgen mediated signaling induces epithelial to mesenchymal transition phenotype in MDA-MB-453 breast cancer cells and human breast tumors

Background: Epithelial-mesenchymal transition (EMT) phenotype is a complex process and plays a central role in tumor progression, aggression, invasion, metastasis, and resistance to therapy. Role of androgen receptor (AR) and androgens in inducing EMT has been well established in experimental systems of prostate cancer. AR is widely expressed in all subtypes of breast cancer (BC) and is considered to have context dependent role based on the steroid hormone microenvironment. Previous studies have shown AR as the only sex steroid receptor detectable in BC metastases and in metastatic lesion. We investigated the role of androgens in driving the EMT phenotype and association of AR induced genes with EMT in BC tumors using public dataset. Methods: We treated AR positive breast cancer cell line MDA-MB-453 with the androgen, dihydrotestosterone (DHT) followed by AR antagonist bicalutamide (Bic) and examined the expression levels of AR induced genes by quantitative real time PCR (qPCR) and AR induced protein GCDFP-15 by western blot. AR driven genes (SEC14L2, C1orf116, FKBP5, UGT2B11, UGT2B28, KCNMA1, PIP and ABCC11) were identified by bioinformatic pipeline using a systematic bioinformatic approach from public microarray data sets derived from AR positive breast cancer cell lines (S Rajarajan et al, SABCS 2021). Mesenchymal phenotype of the cell lines under DHT/Bic was evaluated morphologically and expression levels of EMT markers (ZEB1, Slug, Vimentin) and E-cadherin was estimated by qPCR, western blot and immunofluorescence. Migratory potential of the cell line under treatment was evaluated by wound healing assay and proliferation was examined by the MTT assay. Association of AR induced genes and levels of enzymes involved in intracrinal testosterone metabolism (SRD5A1 & SRD5A3) with EMT in breast tumors was evaluated using transcript data from METABRIC database. EMT scores were derived from previous publications (Byers et al, 2013, Mak et al, 2016) and correlation was tested with AR induced genes. Results: The MDAMB-453 cell line was treated with 10nM DHT for 72hrs and this increased the expression of AR downstream protein GCDFP-15 by 31.47% (p=0.022) when compared to the control. Further, a significant increase in the expression levels of AR driven genes with a fold change >2 was observed in the DHT treated cells (p< 0.05). The expression of GCDP15 protein (p=0.028) and the AR downstream genes (p< 0.05) were significantly repressed upon treatment with bicalutamide. DHT treatment also showed a significant higher expression of EMT master regulator, SLUG (fold change>3, p=0.045) and a wound healing assay showed a 22% increase in migration (p=0.027). The expression of SLUG was significantly repressed (p=0.003) and the migratory ability of the DHT treated cells reduced upon treatment with bicalutamide (p=0.145). We also observed a significant loss of E-cadherin protein (by 23.65%; p=0.024) with DHT treatment and this was completely reversed upon treatment with bicalutamide (p=0.047). No significant change in proliferation was observed among the different treatment conditions. A significant positive correlation was observed between AR induced genes and the EMT scores (p< 0.05). Expression level of SRD5A3 was also positively correlated with EMT score (p=0.043) and AR induced genes (p< 0.05), except SEC14L2. Conclusion: Androgen receptor plays an important role in the biology of breast cancer and is considered a useful marker for prognosis. However, antiandrogen therapies haven’t seen the expected success in clinical trial settings. Our results support the controversial role played by AR in higher androgenic environment within breast cancer and warrant the consideration of the intratumoral levels of sex steroid hormones.

Citation Format: Savitha Rajarajan, Snijesh VP, Madhumathy G Nair, Apoorva D, Chandrakala M, Vidya P Nimbalkar, Maalavika Pillai, Mohit Kumar Jolly, Jyothi S Prabhu. Androgen mediated signaling induces epithelial to mesenchymal transition phenotype in MDA-MB-453 breast cancer cells and human breast tumors [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-19-02.

Cell State Transitions and Phenotypic Heterogeneity in Luminal Breast Cancer Implicating MicroRNAs as Potential Regulators

Luminal breast cancer subtypes respond poorly to endocrine and trastuzumab treatments due to cellular heterogeneity arising from the phenotype transitions, accounted for mainly by the loss of receptor expression. The origins of basal-like and human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer subtypes have been attributed to genetic and protein modifications in stem-like cells and luminal progenitor cell populations, respectively. The post-transcriptional regulation of protein expression is known to be influenced by microRNAs (miRNAs) that are deemed to be master regulators of several biological processes in breast tumorigenesis and progression. Our objective was to identify the fractions of luminal breast cancer cells that share stemness potentials and marker profiles and to elucidate the molecular regulatory mechanism that drives transitions between fractions, leading to receptor discordances. Established breast cancer cell lines of all prominent subtypes were screened for the expression of putative cancer stem cell (CSC) markers and drug transporter proteins using a side population (SP) assay. Flow-cytometry-sorted fractions of luminal cancer cells implanted in immunocompromised mice generated a pre-clinical estrogen receptor alpha (ERα+) animal model with multiple tumorigenic fractions displaying differential expression of drug transporters and hormone receptors. Despite an abundance of estrogen receptor 1 (ESR1) gene transcripts, few fractions transitioned to the triple-negative breast cancer (TNBC) phenotype with a visible loss of ER protein expression and a distinct microRNA expression profile that is reportedly enriched in breast CSCs. The translation of this study has the potential to provide novel therapeutic miRNA-based targets to counter the dreaded subtype transitions and the failure of antihormonal therapies in the luminal breast cancer subtype.

Estimation of ALU Repetitive Elements in Plasma as a Cost-Effective Liquid Biopsy Tool for Disease Prognosis in Breast Cancer

BACKGROUND

Liquid biopsy is widely recognized as an efficient diagnostic method in oncology for disease detection and monitoring. Though the examination of circulating tumor cells (CTC) is mostly implemented for the assessment of genomic aberrations, the need of complex methodologies for their detection has impeded its acceptance in low-resource settings. We evaluated cell-free DNA (cfDNA) as a liquid biopsy tool and investigated its utility in breast cancer patients.

METHODS

Total cell-free DNA was extracted from the plasma of breast cancer patients (n = 167) with a median follow-up of more than 5 years, at various stages of the disease. Quantitative PCR was performed to estimate the copy numbers of two fractions of ALU repetitive elements (ALU 115 and ALU 247), and DNA integrity (DI) was calculated as the ratio of ALU 247/115. Mutations in TP53 and PIK3CA in the cfDNA were estimated by next-gen sequencing (NGS) in a subset of samples. Associations of the levels of both the ALU fragments with various clinico-pathological factors and disease-free survival at various stages were examined. Nomogram models were constructed with clinical variables and ALU 247 levels to predict disease-free survival and the best performing model was evaluated by decision curve analysis.

RESULTS

DI and ALU 247 levels were significantly lower (p < 0.0001) in the post-operative plasma when compared to their pre-surgery levels. DI and ALU 247 were found to be significantly higher in patients with metastasis (p < 0.05). Patients with higher levels of ALU 247 in their post-operative plasma had significant poor disease-free survival (p = 0.005). Higher levels of ALU 247 in the circulation also correlated with low tumor-infiltrating lymphocytes (TIL) within their primary tumors in the ER-negative breast cancer subtype (p = 0.01). Cox proportional hazard analysis confirmed ALU 247 as an independent variable of disease-free survival both in univariate and multivariate analysis [HR 1.3 (95% CI 1.047 to 1.613, p = 0.017)]. The nomogram model showed that the addition of ALU 247 with other variables significantly improved (C-index 0.823) the predictive ability of the model.

CONCLUSION

Our results confirm the utility of cfDNA as an evolving liquid biopsy tool for molecular analysis. Evaluation of larger fragments of cfDNA estimated through ALU 247 can provide vital information concurrent with the pathological process of disease evolution in breast cancer and warrants expansion to other cancer types.

Effect of a Novel Sugar Blend on Weight and Cardiometabolic Health among Healthy Indian Adults: A Randomized, Open-Label Study

Obesity is one of the major factors contributing to noncommunicable diseases (NCDs), which is associated with a high intake of a sugar-rich diet. Sugar blend (a novel combination of sugar and stevia) has half the calories of sugar with the same sweetness at recommended use and offers better compliance. A randomized controlled trial was conducted to evaluate the efficacy and safety of this sugar blend in normal to mildly overweight subjects with a body mass index (BMI) of 23−26 kg/m. Sixty subjects were categorized into Group A: Sugar group (n = 30), and Group B: Sugar blend group (n = 30). The primary outcomes evaluated were weight, waist circumference, hip circumference, waist/hip ratio, BMI, and the secondary outcomes evaluated were lipid profile, random blood sugar, and HbA1c. All these parameters were assessed at baseline, 30 days, 60 days, and 90 days. Group B showed a significantly higher weight loss (p = 0.013) at 90 days compared with Group A. A significant reduction in waist circumference (p < 0.0001) by 4.4 cm was noted at 90 days, in addition to reduction in total cholesterol (p < 0.0001), triglyceride (p = 0.006), LDL cholesterol (p = 0.0490), and VLDL cholesterol (p = 0.006) in Group B compared with the baseline. The study revealed that the sugar blend is an effective formulation in reducing weight, anthropometric factors, and other related metabolic parameters. It has been proven to be well tolerated and promotes weight loss when used in conjunction with a daily balanced diet and exercise plan.

Abstract P5-06-14: A novel combination of a 2 gene score & TIL as a predictive Biomarker for responders to novel therapies in Indian TNBC - A population with greater proportion of TNBCs

Introduction: Triple-Negative Breast Cancer (TNBC) comprises approximately 30% of all breast cancers in Indian women. Given their aggressive nature, TNBCs have high rates of systemic metastasis and mortality with only chemotherapy available for treatment. Compelling evidence has demonstrated the prognostic value of tumor-infiltrating lymphocytes (TILs), in many cancers especially in Breast Cancer and play a critical role in tumour progression, response to therapeutics and prognosis. They are typically measured by H&E staining and immunohistochemistry for research purpose and degree of infiltrate is also known to differ among subtypes. Nonetheless, the literature regarding the types of immune cells characterizing TILs and their prognostic utility in TNBC has been conflicting for lack of accurate “functional” TIL assessments. Herein we have used a combination signature of TILs and a 2 gene immune function expression based signature to develop an unique classifier, to identify a subgroup within TNBC that has better clinical outcome, such as survival and response to treatment. Our findings also suggest a possible use of the score as a predictive biomarker for response to immune checkpoint therapy Patients and Methods: Surgically excised TNBC tumor specimens from 44 women from a single treating hospital in Bangalore, India were accessed under IERB approved protocols and assayed on nCounter® PanCancer Immune Profiling Panel which comprised of 740 genes and characterises 14 different immune cell types. Analysis using Non-negative Matrix factorization (NMF) based unsupervised clustering was done to arrive at stable subtypes characterized by different tumor microenvironments within TNBC. SSGSEA analysis was done to identify immune cell types. TILs were characterised by a pathologist on H&E sections according to guidelines from TIL working group. The Immune classifier was validated on Breast Cancer data sets from TCGA. Results: NMF followed by SAM and PAM analysis yielded 2 stable subtypes (ST1 and ST2) of proportions 59% and 41% respectively. TIL groups also were divided into Dense and Mild groups which were 52% and 48% respectively. Despite similar distributions of the groups, ST1 and ST2 had distinct survival with ST2 having poorer outcome (p=0.023) while the dense and mild TIL groups did not separate as distinct groups. On a closer examination using SSGSEA analysis with Rooney et al signature, ST1 was enriched with T-cells, Dendritic cells, MHC-class 1 and very significantly high cytolytic score (CYT), which was defined by Granzyme A and Perforin expressions, proteins secreted by cytotoxic T cells (p=0.0074). The CYT Score ranged from -35 to 170 and cutoff was based on 75th percentile. We next hypothesized that a combined score of TIL and CYT would represent a functional TIL group with high immune activity. We arrived at a CYT+TIL score based on 75th percentile cut off of CYT and 2 groups of TIL. Of the resultant four groups, TIL High-CYT high that constituted about 20% of all TNBCs indicated an elevated immune response because of their microenvironment constitution and this can be identified using our simple immune classifier. On the other hand, in the TIL-high and CYT-low group, despite lymphocyte migration, outcome was not favorable. The classifier was applied to TNBC from TCGA (n=96) and similar results seen, with ST1 and ST2 which had distinctly separate survival and had similar patterns on CYT high groups. Conclusion: We developed a simple immune classifier with 2 gene signature c and H&E slide TIL assessment for identifying a group with TNBC that can be better targeted with therapies. Our signature is predictive for selecting TNBCs which are potential responders to Immune therapies and has the potential for quick clinical adoption though it requires validation on a larger set.

Citation Format: Aruna Korlimarla, Hari PS, Jyothi S Prabhu, Chantirika Ragulan, Ravi B Diwakar, Sandhya Apachu, Maggie Cheang, Rekha V Kumar, BS Srinath, TS Sridhar, Savitha Rajarajan, Annie Alexander, Anguraj Sadanandam. A novel combination of a 2 gene score & TIL as a predictive Biomarker for responders to novel therapies in Indian TNBC - A population with greater proportion of TNBCs [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-06-14.

Abstract P3-10-06: High levels of miR-18a is associated with increased proliferation but suppression of EMT phenotype in ER negative breast cancer

Introduction: miRNA-based regulation has been implicated in tumor evolution and progression. miR-18a belonging to the miR-17-92 polycistronic cluster has also been reported to have oncogenic effects across multiple cancer types including breast cancer. We have previously demonstrated the epigenetic regulation of ER by miR-18a and its high levels as a poor prognostic marker in ER-positive breast tumors (Nair et al, Cancer Med. 2016). Here, we have examined the effects of high expression of miR-18a in the ER-negative subtype of breast cancer. Methods: 275 surgically excised specimens of primary breast cancers were analyzed. Samples were segregated into ER-positive and ER-negative tumors based on ER positivity as determined by Immunohistochemistry. Relative abundance of hsa-miR-18a-5p in these samples was assessed using a TaqMan qRT-PCR and used to correlate with a probability distribution of proliferation that was derived by fitting a binomial logistic regression model using 4 genes - FOXM1, UBE2C, BIRC5 & ANLN. miR-18a was inhibited using synthetic inhibitors in ER-negative breast cancer cell lines - MDA-MB-468 AND MDA-MB-231. Migratory ability was assessed using wound-healing assays. The expression of miR-18a was further analyzed in ER-negative breast cancer samples from the TCGA (n= 116) and the METABRIC cohort (n=107). ER-negative tumors with higher than the third quartile and lower than the first quartile expression of miR-18a were segregated into tumors with high and low expression, respectively. Functional enrichment of differentially expressed genes (DEGs) between these groups was performed using the G: profiler to identify the deregulated pathways. Result: Evaluation of the levels of miR-18a in 275 breast tumor samples showed that the microRNA was highly expressed (p&lt;0.0001) in the ER-negative tumors (n=105) when compared to ER-positive samples (n=170). The ER-negative tumors were further stratified based on the 3rd quartile expression of miR-18a into high (n=27) and low miR-18a (n=78) expressing tumors. The high miR-18a expressing tumors were associated with a higher proliferation score (p=0.005). Inhibition of miR-18a levels in ER-negative breast cancer increased migration ability up to 33 % in MDA-MB-468 (p=0.009) and up to 26 % in MDA-MB-231 (p=0.0003). Analysis of ER-negative tumors of TCGA and METABRIC cohort revealed that the high miR-18a expressing tumors expressed low levels of EMT master regulators-ZEB1 and ZEB2 and low levels of Matrix metalloproteinases -MMP2, MMP3, MMP10, MMP11, MMP13, and MMP17 (p&lt;0.01). Functional enrichment of differentially expressed genes (DEGs) demonstrated suppression of pathways related to cell motility and migration, ECM activation, Wnt signaling, and Focal adhesion-PI3K-Akt signaling pathways (p&lt;0.01). Conclusion: In ER-positive tumors, high levels of miR-18a are associated with activated EMT, increased migratory ability, and poor prognosis. On the contrary, in ER-negative breast tumors, high levels of miR-18a is associated with a higher rate of proliferation but lower migratory ability and suppression of signaling pathways necessary for an epithelial to mesenchymal transition.

Citation Format: Madhumathy G Nair, Chandrakala M, Apoorva D, Snijesh VP, Jyothi S Prabhu, Savitha Rajarajan, Aruna Korlimarla, Rakesh S Ramesh, Srinath BS, Sridhar TS. High levels of miR-18a is associated with increased proliferation but suppression of EMT phenotype in ER negative breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-10-06.

Abstract P5-04-04: Identification of AR driven tumors within TNBC using a novel gene signature

Background The androgen receptor (AR) is an emerging biomarker and favourable therapeutic target in breast cancer (BC), especially in Triple negative BC (TNBC) which lacks a targeted treatment and shows high molecular heterogeneity. Proportion of AR positive tumours are known to vary (10 to 43%) within TNBC and recent multi-institutional study on AR positive TNBC, showed AR protein status alone is not a reliable prognostic marker for therapeutic response. A deeper examination of AR regulated pathways is necessary to derive AR regulated gene signatures which could identify TNBC tumours truly driven by AR and amenable to anti androgen therapies. In this study, we attempted to develop AR regulated gene signature using gene expression data derived from cell lines under the influence of androgens using systematic bioinformatic approach and tested the ability of the signature to identify AR regulated tumours within TNBC. Methods Microarray data of AR positive BC cell lines (GSE61368 & GSE28305) was used to derive AR regulated genes by a bioinformatic pipeline, using integrated method by incorporating protein interaction networks, topological parameters, and semantic similarity to arrive at final set of 16 genes. Correlation of these genes with AR protein status by reverse phase protein array (RPPA) was evaluated in 447 tumors of TCGA dataset. A 3rd quartile cut-off in the AR expression (by RPPA) was used to classify them as AR positive and negative and a logistic regression model was constructed using positive AR as determinant to generate AR probability score with minimum set of genes. 3rd quartile cut-off in the probability score was used to classify tumors as AR high and low. Distribution of AR probability score was examined in 144 and 187 TNBC tumors in TCGA and METABRIC, respectively. Comparisons between AR high and low tumors were done for clinical parameters, mutational spectrum, expression of ER regulated genes (FOXA1, GATA3 and TFF1) and EMT gene signatures (Byers et al., 2013, Tan et al., 2014). Luminal androgen receptor (LAR) subtype identification by TNBCtype (Lehmann et. al) was done in both datasets to examine the overlap with our method of identification of AR driven tumors within TNBC. Results Logistic regression model identified 5 (SOCS2, ID1,PIP,GADD45 and ZNF689) of the 16 AR regulated genes as predictors for AR probability score which ranged from 0.009 to 0.68 in 144 TNBC tumors within TCGA data. 41/144 (29%) TNBC tumors were categorized as having AR high at cut off of 0.13. The AR probability score ranged from 0.04 to 0.64 in 187 TNBC tumors within METABRIC dataset and 47/187 (25%) were classified as AR driven tumors at cut off of 0.22. Though differences in the clinical variables like age , tumor size and lymph node(LN) status were not different between the AR high and low groups in the TCGA dataset, a significant increase in age, LN positive tumors was observed in the AR high groups in METABRIC. A significant higher PIK3CA mutations was observed in the AR high tumors both in the TCGA and METABRIC (p=0.012 and p&lt;0.0001 respectively) with a proportionate lower p53 mutations in the AR high tumors in both data sets (p=0.03 and p=0.35 respectively). Further, AR high tumors showed significant higher expression of ER regulated genes (TCGA-p&lt;0.05 & METABRIC, p&lt;0.05), were more epithelial by EMT score (TCGA-p&lt;0.05 & METABRIC, p&lt;0.05). Analysis by TNBCtype showed that 30% of AR high tumors in TCGA and 40% of AR high tumors in METABRIC were identified as belonging to LAR subgroup (Lehmann et al). Conclusion Identification of AR driven tumors within TNBC has both prognostic and predictive utility. Methods using limited number of AR regulated genes could be easily applied to larger BC cohorts to identify TNBC tumours driven by AR signalling and may respond well to anti-androgen therapies.

Citation Format: Savitha Rajarajan, Snijesh V.P, Maalavika Pillai, Mohit Kumar Jolly, Jyothi S Prabhu. Identification of AR driven tumors within TNBC using a novel gene signature [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-04-04.

NGS-based profiling of key cancer genes in Indian triple-negative breast cancer patients reinforces molecular heterogeneity of the disease

Triple-negative breast cancers (TNBC) are one of the most aggressive forms of breast cancers. With poor patient outcomes, it presents a great burden on the healthcare systems. There have been some efforts to explore the genomic changes that occur in TNBCs. However, there is not enough data on Indian TNBCs. We sought to understand the mutational landscape of key cancer-associated genes in Indian TNBC patients using TruSeq Cancer Amplicon Panel. We sequenced 51 TNBC patient samples and found great heterogeneity amongst samples with respect to the genomic variants. Several previously reported including alterations in PI3K-AKT pathway genes were also identified. Likewise, we identified several novel high-frequency variants, for example, GNAQ F341S (17%), the functional role of which remains unclear. Our study lays the foundation of larger efforts needed to understand the genomic landscape of Indian TNBCs which can aid in classification and better therapeutic management of patients.

Abstract PS6-55: The prognostic utility of AR/ER ratio in young women with breast cancer

Background

World over, less than a quarter of breast cancer diagnoses are in premenopausal women. However, in India premenopausal women constitute half of all women with breast cancer in most hospital case series. Most of these women present at advanced stages with aggressive subtypes of disease and hence the high mortality.The role and utility of detecting androgen receptor (AR) expression in the different sub-types of breast cancer, especially the ones without hormone receptor expression is yet to be firmly established. Evidence from previous studies is suggestive of its beneficial role in hormone receptor positive (HR+) breast cancer. The biological function of AR on the mammary epithelium is determined by the Estrogen receptor (ER) context, in that, it is found to be anti-proliferative in ER positive tumors while it is thought to promote growth in the absence of ER activity. An interesting approach to representing this interplay is as a ratio between AR/ER expressions. As expected, the ratio has been shown to be positively correlated with better outcomes in hormone receptor cancers, mostly in postmenopausal women. The effect of a high ratio in ER negative tumors seems more complicated. In this study, we have evaluated the AR/ER ratio specifically in patients younger than 50 years in whom the estrogenic influence is dominant due to their premenopausal status.

Materials and Methods

Tumor samples from patients 50 years or younger were chosen from a larger cohort of 275 patients with median follow up of 72 months. Expression of ER and AR proteins were detected by immunohistochemistry (IHC), and the transcript levels of ESR1 and AR were determined by quantitative PCR. Relative normalized units of their gene expression were used to calculate the AR/ER ratio. A cut-off at the 3^rd quartile was used to divide tumors into categories of high and low ratios. Clinical characteristics were compared between the low and high ratio groups along with IHC subtype distribution (HR+, HER2+ and Triple negative (TNBC)). Kaplan Meier curves was used for survival analysis and Cox proportional hazard analysis model was used to calculate the hazard ratio (HR). The results were validated in METABRIC dataset.

Results

Eighty-eight (32%) patients were <50 years with a mean age of 43 years. AR/ER ratio ranged between 0.6 to 3.5 with a mean of 1.5. Sixty-six tumors were categorized as low and 22 were high based on the 3Q cut off (1.7). Clinical characters such as age, tumor size, grade, stage of disease was not different between the high and low ratio categories. Distribution of IHC subtypes among each group showed high ratio category had 64% TNBC tumors (p<0.0001). Tumors with high ratio had poor disease-free survival, (HR-2.6(95% CI-1-6.9) p-0.03). Trends in the METABRIC dataset was similar with 411(21%) patients <50 years. Ninety-seven patients with high ratio had significantly poor disease-free survival (HR-1.95 (95% CI-1.3-2.7) p-0.000).

Conclusion

Interaction between AR and ER is known to influence the AR activity and our results reiterate prognostic ability of AR/ER ratio even in young patients of breast cancer. Our results suggest androgenic influences on clinical progression of breast cancer in this age group mediated through AR, has to be examined by its level in relation to the activity of ER, particularly in hormone receptor negative breast cancers. Even more importantly, examining these influences in the context of the menopausal status might help identify subgroups of patients most likely to benefit from interventions targeted at AR.

CDX2 inducible microRNAs sustain colon cancer by targeting multiple DNA damage response pathway factors

Meta-analysis of transcripts in colon adenocarcinoma patient tissues led to the identification of a DNA damage responsive miR signature called DNA damage sensitive miRs (DDSMs). DDSMs were experimentally validated in the cancerous colon tissues obtained from an independent cohort of colon cancer patients and in multiple cellular systems with high levels of endogenous DNA damage. All the tested DDSMs were transcriptionally upregulated by a common intestine-specific transcription factor, CDX2. Reciprocally, DDSMs were repressed via the recruitment of HDAC1/2-containing complexes onto the CDX2 promoter. These miRs downregulated multiple key targets in the DNA damage response (DDR) pathway, namely BRCA1, ATM, Chk1 (also known as CHEK1) and RNF8. CDX2 directly regulated the DDSMs, which led to increased tumor volume and metastasis in multiple preclinical models. In colon cancer patient tissues, the DDSMs negatively correlated with BRCA1 levels, were associated with decreased probability of survival and thereby could be used as a prognostic biomarker. This article has an associated First Person interview with the first author of the paper.

Pre-Menopausal Women With Breast Cancers Having High AR/ER Ratios in the Context of Higher Circulating Testosterone Tend to Have Poorer Outcomes

Purpose

Women with breast tumors with higher expression of AR are in general known to have better survival outcomes while a high AR/ER ratio is associated with poor outcomes in hormone receptor positive breast cancers mostly in post menopausal women. We have evaluated the AR/ER ratio in the context of circulating androgens specifically in patients younger than 50 years most of whom are pre-menopausal and hence have a high estrogenic hormonal milieu.

Methods

Tumor samples from patients 50 years or younger at first diagnosis were chosen from a larger cohort of 270 patients with median follow-up of 72 months. Expression levels of ER and AR proteins were detected by immunohistochemistry (IHC) and the transcript levels by quantitative PCR. Ciculating levels of total testosterone were estimated from serum samples. A ratio of AR/ER was derived using the transcript levels, and tumors were dichotomized into high and low ratio groups based on the third quartile value. Survival and the prognostic significance of the ratio was compared between the low and high ratio groups in all tumors and also within ER positive tumors. Results were further validated in external datasets (TCGA and METABRIC).

Results

Eighty-eight (32%) patients were ≤50 years, with 22 having high AR/ER ratio calculated using the transcript levels. Circulating levels of total testosterone were higher in women whose tumors had a high AR/ER ratio (p = 0.02). Tumors with high AR/ER ratio had significantly poorer disease-free survival than those with low AR/ER ratio [HR-2.6 (95% CI-1.02-6.59) p = 0.04]. Evaluation of tumors with high AR/ER ratio within ER positive tumors alone reconfirmed the prognostic relevance of the high AR/ER ratio with a significant hazard ratio of 4.6 (95% CI-1.35-15.37, p = 0.01). Similar trends were observed in the TCGA and METABRIC dataset.

Conclusion

Our data in pre-menopausal women with breast cancer suggest that it is not merely the presence or absence of AR expression but the relative activity of ER, as well as the hormonal milieu of the patient that determine clinical outcomes, indicating that both context and interactions ultimately influence tumor behavior.

Triple-negative breast cancers with expression of glucocorticoid receptor in immune cells show better prognosis

Background

Glucocorticoid receptor (GR) is shown to have variable frequency of expression in invasive tumors of the breast. Investigation of additional nuclear receptors like GR in receptor negative tumors like triple negative breast cancer (TNBC) may have prognostic and therapeutic significance.

Methods

Expression of GR was evaluated by immunohistochemistry in 175 tumors of invasive breast cancer with long term follow up. GR Expression was separately evaluated in invasive tumor cells, stromal cells and tumor infiltrating lymphocytes (TIL's). Staining pattern was categorised as positive when more than 1% of the cells stained in each subpopulation of cells. Disease free survival was analysed between GR positive and negative status by Kaplan Meier analysis.

Results

Of the 175 tumors, 121 (70%) were ER positive, 53 (30%) were ER negative and 29% (51) were triple negative. 74% (130/175) tumors showed expression of GR in invasive tumor cells while (84%) 147/175 had expression in TIL's. No significant difference in distribution of GR was noted between ER positive and ER negative tumors (78% vs 66%, p-0.1). Of the TNBC's 54% (28/51) and 70% (36/51) showed expression of GR in invasive tumor and TIL's respectively. Overall, GR positive tumors had significant better survival than GR negative tumors (mean survival time of 85 vs 59 months respectively, p-0.04) Contrary to the reports that GR expression in TIL's are associated with immunosuppressive activity in model systems, TNBC's with increased expression of GR in immune cells were associated with better survival (Mean survival time 74 vs 41 months, log rank test- p-0.03). TNBC tumors which were GR negative had higher lymph node metastases (p-0.04) and none of the other clinical features like age, menopausal state, tumor size and grade were different between GR positive and negative tumors within TNBC.

Conclusions

Glucocorticoids (GC) are often used to alleviate the adverse symptoms during chemotherapy. Determining the GR status is of importance due to the pro cell survival effect of the glucocorticoids mediated through GR during chemotherapy. Though GC mediated effects on chemotherapy are controversial, our results indicate favourable effects in TNBC.

miRNAs: Critical mediators of breast cancer metastatic programming

MicroRNA mediated aberrant gene regulation has been implicated in several diseases including cancer. Recent research has highlighted the role of epigenetic modulation of the complex process of breast cancer metastasis by miRNAs. miRNAs play a crucial role in the process of metastatic evolution by facilitating alterations in the phenotype of tumor cells and the tumor microenvironment that promote this process. They act as critical determinants of the multi-step progression starting from carcinogenesis all the way to organotropism. In this review, we focus on the current understanding of the compelling role of miRNAs in breast cancer metastasis.

Abstract PS19-19: Whole exome sequencing and BRCAness estimation in TNBCs and their correlation with response to platinum

Background: Triple-Negative Breast Cancer (TNBC) comprises approximately 30% of all breast cancers in Indian women. The hallmark of TNBC is genomic instability with very high rates of TP53 mutation. BRCAness has been defined by Ashworth et al (2004 &2014), as the phenocopying of BRCA1&2 mutation by alternate genetic or Epigenetic mechanisms. The consequence of this is DNA damage repair (DDR) deficiency. Though PARP inhibitors have been of utility in treating this subset of TNBC, trials have in general not found an unequivocal support for the use of platinum. We have developed an assay for BRCAness, the BRCA1 deficiency score (BDS) (Korlimarla et al 2016). In this study, we have applied BDS assay in tandem with whole exome sequencing to a small retrospective series of TNBC patients more than half of whom were treated with Platinum. Methods: 40 TNBC primary specimens along with complete clinical data from a retrospective series at the SSCHRC were obtained under all IERB approvals and informed patient consent for BDS assay and mutational analysis. BDS assay is a multianalyte assay involving measurement of BRCA1 (Transcript and protein) as well as additional epigenetic regulators of BRCA1, mir182 and ID4. Whole Exome Sequenced (WES) using the Agilent Sureselect V6 kit on Illumina HiSeq platform. Variant calling analysis was performed using GATK Mutect2 with Hg38 reference genome following the best practice workflow. Variants annotated as protein affecting based on their functional impact prediction and mapped to known cancer related genes (from COSMIC), were selected. Results: Clinical details: Mean age of patient in the series was 49. 37/40 qualified for BDS assay. 21/37 (57%) patients were treated with Carboplatin in combination with Docetaxel in an adjuvant setting. Remaining patients were treated with Cyclophosphamide Adriamycin with or without Docetaxel. 15/37 (45%) were BRCA1 deficient and10/15 were treated with Platinum and 8 (80%) were responders.

39 passed QC and considered for analysis. Spectrum of variants were missense mutations (86.5%), followed by stop gained (5.91%) and frame shift (3.76%). Results were compared to TCGA TNBC set (n=123). The most frequently mutated gene was TP53 (62%) as reported in TCGA. We also report higher frequency of deleterious mutations on DNA damage repair (DDR) genes like ATM and BRCA2 (15%). Response to Platinum therapy in this subset, correlated with Mutations in DNA damage repair genes (p ≤ 0.003). 4/6 samples mutated were also In the BDS deficient group. BRCAness score for predicting Platinum response also correlated significantly (p ≤ 0.05). Other genes which showed significant alterations were KMT2A and KMT2D (15% and 13%) which encode the histone methyl transferase and are responsible in altering the chromatin structure and RECQL4 (10%) which is a helicase involved in DDR Conclusion: Both BRCAness and mutation profile identified a DDR deficient group within TNBC patients. In addition to TP53 which is the most frequently mutated gene, our small sample set has shown higher frequencies of mutations in DDR genes like ATM and BRCA2. This group of patients showed favourable response to platinum therapy. Since very little is known about the molecular heterogeneity of TNBCs in Indian patients, our analysis aids in identification of actionable mutations in TNBCs and may be of use in selection of patients for platinum therapy.

CHARACTERSn%Platinum Treatment - ( n )Treatment response%BDS3721Deficient154513BRCA1 deficient response861Proficient19518BRCA1 Proficient response450Undet34

Citation Format: Aruna Korlimarla, Sabarinathan Radhakrishnan, Snijesh VP, Jyothi S Prabhu, Naveen Luke Demonte, Savitha Rajarajan, Yatish Patil, Ravi Diwakar, Sandhya Apachu, BS Srinath, Sridhar TS, Anguraj Sadanandam. Whole exome sequencing and BRCAness estimation in TNBCs and their correlation with response to platinum [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS19-19.

High expression of ACE2 in HER2 subtype of breast cancer is a marker of poor prognosis

Background

ACE2 a key molecule of the Renin-Angiotensin system has been identified as the receptor for SARS-CoV-2 entry into human cells. In the context of human cancers, there is evidence that ACE2 might function as a tumor suppressor. The expression levels of ACE2 among the different subtypes of breast cancer has not been investigated.

Methods

We have examined the differential expression of ACE2 and its correlation with prognosis in breast cancer subtypes using the METABRIC (n = 1898) and TCGA (n = 832) cohorts. Correlations were evaluated by Pearsons's correlation co-efficient and Kaplan-Meier analysis was used to estimate differences in disease-free survival between the ACE2 high and ACE2 low groups.

Results

There is minimal expression of ACE2 in the luminal classes, but significantly higher levels in the Basal-like and HER2-enriched subclasses. Metastatic biopsies of these tumor types also show enhanced expression of ACE2. High levels of ACE2 correlated with decreased disease-free survival in the HER2-enriched subtype, and it was positively correlated with EGFR expression.

Conclusion

These observations suggest ACE2 might function as a context dependent factor driving tumor progression in breast cancer and permit new opportunities for targeted therapy.

Gender disparity in COVID-19: Role of sex steroid hormones

The emerging pandemic of COVID-19 caused by the novel pathogenic human coronavirus SARS-CoV-2 has caused significant morbidity and mortality across the globe, prompting the scientific world to search for preventive measures to interrupt the disease process. Demographic data indicates gender-based differences in COVID-19 morbidity with better outcome amongst females. Disparity in sex-dependent morbidity and mortality in COVID-19 patients may be attributed to difference in levels of sex steroid hormones -androgens and estrogens. Evidence suggests that apart from the regulation of viral host factors, immunomodulatory and cardioprotective roles exerted by estrogen and progesterone may provide protection to females against COVID-19. Exploring the underlying mechanisms and beneficial effects of these hormones as an adjuvant to existing therapy may be a step towards improving the outcomes. This article aims to review studies demonstrating the role of sex steroidal hormones in modulating SARS-CoV-2 host factors and summarize plausible biological reasons for sex-based differences seen in COVID-19 mortality.

Identification of colorectal cancers with defective DNA damage repair by immunohistochemical profiling of mismatch repair proteins, CDX2 and BRCA1

Colorectal cancer (CRC) is a complex disease as shown by consensus classification. The present study attempted to identify subtypes with known prognostic markers for better clinical management. A total of 72 CRC tumors were examined for the expression of mismatch repair (MMR) proteins, along with caudal-type homeobox protein 2 (CDX2) and BRCA1, by immunohistochemistry. Tumors were assigned based on the presence or loss of MMR proteins as proficient or deficient. Correlations were examined with CDX2 and BRCA1 along with clinico-pathological features. Expressional pattern of microRNAs (miRs/miRNAs), such as miR-183-96-182, known to be associated with defective DNA damage repair were evaluated by reverse transcription-quantitative PCR. A total of 22% of the CRC tumors were assigned as deficient in mismatch repair. 71% of the tumors expressed CDX2 while only 21% had nuclear expression of BRCA1. Loss of CDX2 protein was higher in the deficient subtype compared with the proficient subtype. A total of 14% of the tumors had dual loss of MMR and BRCA1 proteins and showed aggressive clinical features in addition to elevated expression of DNA damage repair microRNAs. The present study shows the presence of a small proportion of colorectal tumors with dual loss of key proteins involved in DNA damage repair which may be amenable to specific therapy. The implication of the present observations warrants investigation in a larger patient cohort with prognostic information.

miR-18a activates Wnt pathway in ER-positive breast cancer and is associated with poor prognosis

Despite the established benefits of long‐term endocrine therapy, women with hormone receptor‐positive breast cancer remain at risk for late relapse. The basis of this is multi‐factorial including genetic, epigenetic, and host factors. In this study we have explored the epigenetic regulation of estrogen receptor (ER)‐dependent molecular and cellular phenotype by hsa‐miR‐18a‐5p using well‐established human ER‐positive (ER+) breast cancer cell lines. miR‐18a was overexpressed in MCF7 and ZR‐75‐1 and this led to an increase in the proliferative ability of the cells and concurrently resulted in decreased expression of luminal markers and higher expression of the basal marker, cytokeratin 14. The cells became more migratory with a significant repression of E‐cadherin and activation of the Wnt noncanonical pathway. We observed an activation of the planar cell polarity (PCP) pathway with increased activation of JNK pathway and eventually change in actin dynamics. There was increased F‐actin polymerization in cells with higher expression of miR‐18a. Examination of miR‐18a expression in a set of human ER+ breast cancer specimens showed a negative correlation between miR‐18a and ESR1 transcripts as well as ER protein. Kaplan‐Meier survival analysis of the cohort stratified by tumor hsa‐miR‐18a‐5p levels produced significant differences in disease‐free survival (log rank P < .05). This observation was independently validated in the METABRIC cohort. These data provide support for a role of hsa‐miR‐18a‐5p in altering the proliferative and migratory behavior of ER+ cells and its potential utility as a prognostic marker in clinical ER+ breast cancers.

Abstract P3-09-05: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Chakladar M, Nair MG, Prabhu JS, Cohen S, Srinivas ST, Lingadahalli SS. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-09-05.

Abstract P4-10-12: Treatment decision making, and strategies for coping with financial stress in Indian women diagnosed with breast cancer and their families

Introduction: In spite of rapid urbanization and modernization the family remains central in the socio-cultural structure of India. The individuals are enmeshed into this unit and tend to be interlinked financially, emotionally and socially. The head of this family unit tends to be a male more often than not. As is well known, despite recent attempts by the governments at the state and centre at providing health coverage for cancer through regional cancer centres, a majority have to raise the money for cancer care by themselves. We have examined the role of the family in treatment decision making and in the strategies employed to raise the money and cope with the financial stress imposed by a diagnosis of breast cancer.

Method: 378 women with breast cancer were enrolled into a longitudinal study at first diagnosis between the years 2008-2012, at two tertiary care hospitals in Bangalore, India. The median follow up as of May 31st 2017 is 78 months with only 2% loss to follow-up over the past 8 years. Follow-up was maintained by frequent meetings between a counselling psychologist (AA) and the patient and/or a family member. The frequency of meetings was monthly during the initial treatment and then quarterly over the next 5 years. Information on demographics was collected during the treatment phase and information on the psychosocial aspects was collected in non-structured interactions subsequently. This information included details of support structure, decision making, and financial arrangements.

Results: This is a predominantly urban cohort with 80% being urban. The median age of patients at first diagnosis was 55 years. Almost all of our patients (99%) had the support of one or more family members. We analysed the pattern of decision making for treatment and in half of all cases either the husband or the son were the decision makers. In an additional 15% daughters and other relatives were the primary decision makers. Approximately a third of women made the decision concerning treatment themselves, and these women tended to be college educated (51% vs 16%) and employed (53% vs 12%).

30% of the patients met the costs incurred through medical insurance plans purchased by the family. Another quarter of patients were able to meet the costs from their savings. 45% had difficulty in finding the money for treatment and 15% took personal loans while 30% had to sell land/gold ornaments or take loans against assets of these sorts. Only (3%) discontinued the treatment due to financial difficulties. As in the case of decision making those who had the financial resources tended to be more educated (41% vs 11%), and were employed (31% vs 21%).

Conclusion: The data from a predominantly urban cohort of breast cancer enrolled between 2008-2012, supports the general belief that in India the family remains the fulcrum of an individual during crises, and not surprisingly education and employment lead to both psychological and economic emancipation of women.

Citation Format: Alexander A, Kaluve R, Prabhu JS, Korlimarla A, BS S, Manjunath S, Patil S, KS G, Sridhar TS. Treatment decision making, and strategies for coping with financial stress in Indian women diagnosed with breast cancer and their families [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-10-12.

Dissecting the Biological Heterogeneity within Hormone Receptor Positive HER2 Negative Breast Cancer by Gene Expression Markers Identifies Indolent Tumors within Late Stage Disease

Hormone receptor positive (HR+) breast cancers are a heterogeneous class with differential prognosis. Although more than half of Indian women present with advanced disease, many such patients do well. We have attempted identification of biologically indolent tumors within HR+HER2- tumors based on gene expression using histological grade as a guide to tumor aggression. 144 HR+HER2- tumors were divided into subclasses based on scores derived by using transcript levels of multiple genes representing survival, proliferation, and apoptotic pathways and compared to classification by Ki-67 labeling index (LI). Clinical characters and disease free survival were compared between the subclasses. The findings were independently validated in the METABRIC data set. Using the previously established estrogen receptor (ER) down stream activity equation, 20% of the tumors with greater than 10% HR positivity by immunohistochemistry (IHC) were still found to have inadequate ER function. A tumor aggression probability score was used to segregate the remainder of tumors into indolent (22%) and aggressive (58%) classes. Significant difference in disease specific survival was seen between the groups (P = .02). Aggression probability based subclassification had a higher hazard ratio and also independent prognostic value (P < .05). Independent validation of the gene panel in the METABRIC data set showed all 3 classes; indolent (24%), aggressive (68%), and insufficient ER signaling (7%) with differential survival (P = .01). In agreement with other recent reports, biologically indolent tumors can be identified with small sets of gene panels and these tumors exist in a population with predominantly late stage disease.

HR+HER2− breast cancers with growth factor receptor–mediated EMT have a poor prognosis and lapatinib downregulates EMT in MCF-7 cells

Despite an overall good prognosis, a significant proportion of patients with hormone receptor positive human epidermal growth factor receptor 2 negative breast cancers develop distant metastases. The metastatic potential of epithelial cells is known to be regulated by tumor–stromal interaction and mediated by epithelial-to-mesenchymal transition. Hormone receptor positive human epidermal growth factor receptor 2 negative tumors were used to estimate markers of epithelial-to-mesenchymal transition, and the luminal breast cancer cell line MCF-7 was used to examine the interactions between integrins and growth factor receptors in causation of epithelial-to-mesenchymal transition. A total of 140 primary tumors were sub-divided into groups enriched for the markers of epithelial-to-mesenchymal transition (snail family transcriptional repressor 2 and integrin β6) versus those with low levels. Within the epithelial-to-mesenchymal transition+ tumors, there was a positive correlation between the transcripts of integrin β6 and growth factor receptors—human epidermal growth factor receptor 2 and epidermal growth factor receptor. In tumors enriched for epithelial-to-mesenchymal transition markers, patients with tumors with the highest quartile of growth factor receptor transcripts had a shorter disease-free survival compared to patients with low growth factor receptor expression by Kaplan–Meier analysis (log rank, p = 0.03). Epithelial-to-mesenchymal transition was induced in MCF-7 cells by treatment with transforming growth factor beta 1 and confirmed by upregulation of SNAI1 and SNAI2 transcripts, increase of vimentin and integrin β6 protein, and repression of E-cadherin. Treatment of these cells with the dual-specificity tyrosine-kinase inhibitor lapatinib led to downregulation of epithelial-to-mesenchymal transition as indicated by lower levels of SNAI1 and SNAI2 transcripts, integrin αvβ6, and matrix metalloproteinase 9 protein. The results suggest that synergistic interactions between growth factor receptors and integrin β6 could mediate epithelial-to-mesenchymal transition and migration in a subset of luminal breast cancers and lapatinib might be effective in disrupting this interaction.

Abstract P4-07-10: Epithelial mesenchymal transition associated with high miR-221 and integrin β6 leads to poor prognosis in hormone receptor positive HER2 negative breast cancers

Background: MicroRNA mediated molecular alterations are involved in the initiation and progression of cancer. Altered expression of multiple microRNAs is associated with endocrine resistance in hormone receptor positive HER2 negative (HR+/HER2-ve) cancer. The role of miR-221 in inducing epithelial to mesenchymal transition (EMT) is well documented especially in cell line model systems. However, the detailed mechanism of specific microRNAs in intrinsic and acquired resistance to endocrine therapy needs to be worked out. In addition, more needs to be done in the documentation of these mechanisms in human breast cancer specimens with complete clinical documentation and long-term follow-up. In this study, we have evaluated the clinical significance of miR-221 and its mechanistic role in EMT using human specimens and cell line models.

Materials and Methods: Formalin fixed paraffin embedded tumor from 129 HR+/HER2-ve breast cancer patients with a median follow up of 63 months were used for estimation of miR-221 by quantitative real time PCR. Expression levels of genes which are direct targets of miR-221 and related genes in EMT were analysed from these tumors. Survival between miR-221 high and low groups was compared by Kaplan Meier survival curves and prognostic relevance was estimated by Cox proportional hazard model.

Cell line experiments to investigate the role of miR-221 in inducing EMT through integrin β6 are underway in both wild type and tamoxifen resistant MCF-7 cell lines (A gift from Prof Ben Ho Park, Johns Hopkins University School of Medicine).

Results: A significant elevated level of miR-221 was observed in small proportion (14%) of HR+/HER2-ve tumors. miR-221 expression had an inverse correlation with both ER protein and ESR1 mRNA levels within HR+/HER2-ve tumors. Tumors with high levels of miR-221 showed significantly higher expression of integrin β6 which is a robust marker of EMT. Patients with high expression of miR-221 had a poorer survival in Kaplan Meier analysis.

Results of interrogation of EMT mediated through integrin related pathways involving miR-221 in cell line models will be presented.

Discussion: The association between miR-221 and integrin β6 in HR+/HER2-ve breast cancer with endocrine resistance suggests a potential link between an epigenetic regulator and a mediator of tumor-stromal interaction. The other mediators involved in this pathway are being investigated. miR-221 could be potentially used as a marker for identification of a poor prognostic subtype within HR+/HER2-ve breast cancers.

Citation Format: Prabhu JS, Kaul R, Korlimarla A, Desai K, Gangadharan C, Rajarajan S, Nair MG, Alexander A, Kaluve R, Manjunath S, Correa M, Prasad MSN, Patil S, Srinath BS, Sridhar TS. Epithelial mesenchymal transition associated with high miR-221 and integrin β6 leads to poor prognosis in hormone receptor positive HER2 negative breast cancers [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-07-10.

Abstract P4-06-11: Differential regulation of microRNAs and integrins influences metastatic potential: Comparison between locally invasive BT-474 and metastatic MDA-MB-231 xenografts

Background: Generation of BT-474 and MDA-MB-231 xenografts in immunocompromised mice provides one means of dissecting the molecular events involved in local invasion versus distant metastasis. Recently, Glunde et al have shown an interdependence of genes involved in cell-cell and cell-matrix adhesion (E-cadherin and integrin β1) and extra-cellular matrix degradation (MMP-2 and 9) in allowing cells to metastasize. Further, Fite el al have identified a set of microRNAs (miRs) up-regulated by E-cadherin (a pre-EMT marker) and down-regulated by Vimentin (post-EMT marker) in acquiring an invasive phenotype. We have performed a detailed analysis of integrins, matrix metallo-proteases and key miRs to better understand the molecular events underlying these disparate behaviours.

Methods: We injected BT-474 (N=5) and MDA-MB-231 (N=5) cells orthotopically into SCID mice. Xenografts were assessed for local growth rate and monitored for distant metastasis. The implanted tumors as well as the distant metastatic foci were harvested. Markers involved in local invasion, distant metastasis and tumor-stroma interactions including miRs were compared between BT-474 and MDA-MB-231 cell lines and their xenografts by q-RT-PCR, immunofluorescence and immunohistochemistry.

Results: As expected BT-474 xenografts showed a higher rate of tumor growth when compared to MDA-MB-231. Histological examination of BT-474 tumors confirmed only locally invasive tumor growth with infiltrated blood capillaries and vessels; no macro and microscopic metastases were observed in the organs collected. On the contrary, MDA-MB-231 xenografts showed highly undifferentiated tumor growth and frank lung metastasis and extra-pulmonary tumor growth in one of the five mice injected despite slow rate of local growth. Expression of matrix metalloproteases – MMP-2 & 9 was more than 30 fold upregulated in MDA-MB-231 xenografts as compared to BT-474. Elevated level of E-cadherin was observed in BT-474 but was absent in MDA-MB-231.

The most interesting differences were seen in the levels of miRs and cell-surface integrins. High levels of miR-18a, miR-93 and miR-182 were observed in BT-474 implants when compared to MDA-MB-231 which had a much lower level of these miRs. On the contrary, higher levels of integrin β3, and β1 were observed in MDA-MB-231 tumors when compared to BT-474. Integrin β6 was absent in both. The reciprocal relationship between these markers is being examined and compared between locally invasive tumors and metastatic triple negative breast cancers from our case series of human specimens (N=250).

Conclusion: miRs and integrins known to be involved in invasion are differentially regulated in tumors that are locally invasive compared to ones with distant metastasis. The level of the key targets of these miRs as well as additional integrins is being examined. Understanding the epigenetic regulations leading to metastasis via tumor-stroma interaction might help in discerning differential tumor behaviour.

Citation Format: Lawrence PV, Desai K, Prabhu JS, Korlimarla A, Nair MG, Sridhar TS. Differential regulation of microRNAs and integrins influences metastatic potential: Comparison between locally invasive BT-474 and metastatic MDA-MB-231 xenografts [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-06-11.

Data on alteration of hormone and growth factor receptor profiles over progressive passages of breast cancer cell lines representing different clinical subtypes

Human breast cancers are a highly heterogeneous group of tumours consisting of several molecular subtypes with a variable profile of hormone, growth factor receptors and cytokeratins [1]. Here, the data shows immunofluorescence profiling of four different cell lines belonging to distinct clinical subtypes of breast cancer. Post revival, the cell lines were passaged in culture and immunophenotyping was done for ER, HER-2, AR and EGFR. Data for the markers from early passage (5th) through passages as late as 25 for the different cell lines is presented.

High expression of integrin β6 in association with the Rho-Rac pathway identifies a poor prognostic subgroup within HER2 amplified breast cancers

Integrin αvβ6 is involved in the transition from ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) of the breast. In addition, integrin β6 (ITGB6) is of prognostic value in invasive breast cancers, particularly in HER2+ subtype. However, pathways mediating the activity of integrin αvβ6 in clinical progression of invasive breast cancers need further elucidation. We have examined human breast cancer specimens (N = 460) for the expression of integrin β6 (ITGB6) mRNA by qPCR. In addition, we have examined a subset (N = 147) for the expression of αvβ6 integrin by immunohistochemistry (IHC). The expression levels of members of Rho–Rac pathway including downstream genes (ACTR2,ACTR3) and effector proteinases (MMP9,MMP15) were estimated by qPCR in the HER2+ subset (N = 59). There is a significant increase in the mean expression of ITGB6 in HER2+ tumors compared to HR+HER2‐ and triple negative (TNBC) subtypes (P = 0.00). HER2+ tumors with the highest levels (top quartile) of ITGB6 have significantly elevated levels of all the genes of the Rho–Rac pathway (P‐values from 0.01 to 0.0001). Patients in this group have a significantly shorter disease‐free survival compared to the group with lower ITGB6 levels (HR = 2.9 (0.9–8.9), P = 0.05). The mean level of ITGB6 expression is increased further in lymph node‐positive tumors. The increased regional and distant metastasis observed in HER2+ tumors with high levels of ITGB6 might be mediated by the canonical Rho–Rac pathway through increased expression of MMP9 and MMP15.

A Majority of Low (1-10%) ER Positive Breast Cancers Behave Like Hormone Receptor Negative Tumors

Background: The 2010 guidelines by ASCO-CAP have mandated that breast cancer specimens with ≥1% positively staining cells by immunohistochemistry should be considered Estrogen Receptor (ER) positive. This has led to a subclass of low-ER positive (1-10%) breast cancers. We have examined the biology and clinical behavior of these low ER staining tumors.

Methods: We have developed a probabilistic score of the “ER-positivity” by quantitative estimation of ER related gene transcripts from FFPE specimens. Immunohistochemistry for ER was done on 240 surgically excised tumors of primary breast cancer. Relative transcript abundance of 3 house-keeping genes and 6 ER related genes were determined by q-RT PCR. A logistic regression model using 3 ER associated genes provided the best probability function, and a cut-off value was derived by ROC analysis. 144 high ER (>10%), 75 ER negative and 21 low-ER (1-10%) tumors were evaluated using the probability score and the disease specific survival was compared.

Results: Half of the low-ER positive tumors were assigned to the ER negative group based on the probability score; in contrast 95% of ER negative and 92% of the high ER positive tumors were assigned to the appropriate ER group (p<0.0001). The survival of the low-ER group was intermediate between that of the high ER positive and ER negative groups (p<0.05).

Conclusion: Our results suggest that the newly lowered ASCO-CAP criteria for ER positivity, leads to the false categorization of biologically ER negative tumors as ER positive ones. This may have particular relevance to India, where we have a much higher proportion of ER negative tumors in general.

Abstract P4-07-09: An approach to the identification of tumors driven by HER2 using the integrated activity of oncomiR miR-21 along with HER2 enriched genes

Introduction: The initial identification of HER2 as a driver in a subset of breast cancers was at the level of DNA (amplification), and subsequently noted at the level of transcripts and protein as well. However, the clinical selection of patients for treatment with Trastuzumab, has been through either IHC (protein) or FISH (DNA amplification) and not through transcript abundance. Interestingly, in most studies that have estimated transcript abundance in primary tumors, the proportion of patients that demonstrate increased transcript levels (termed HER2 Enriched) have tended to be slightly larger than the clinical HER2+ category.

A more clinically useful measure might be proof of HER2 downstream activity that might help separate tumors being driven significantly by HER2 from ones where its role is supportive. One of the many consequences of HER2 over-expression is activation of the oncomiR, miR-21 via the MAPK pathway. miR-21 in turn is known to epigenetically regulate multiple targets including the tumor suppressors PTEN and PDCD4. While these molecular mechanisms have been demonstrated convincingly in breast cancer cell lines, clinical studies of these alterations in large numbers are yet to be reported. In this study we have examined the relationship between clinical HER2 positivity and miR-21 levels in 124 surgically excised breast cancer specimens.

Methods: We selected 124 surgically excised specimens of primary breast cancers from our cohort that by HER2 immunohistochemistry (IHC) comprised 42 positive, 62 negative and 20 equivocal. Relative abundance of miR-21 was assessed using a TaqMan qRT-PCR, with normalization by RNU48. Relative transcript abundance of a set of 6 genes (HER2, GRB7, MLN64 and 3 reference genes) were evaluated by SYBR Green real time qPCR.

Results: The majority of tumors that were clinically HER2+ over expressed miR-21. A concordance with an AUC of 96% at 100% sensitivity and 85% specificity was noted. There is a highly significant differential expression of miR-21 between HER2 positive, negative and equivocal samples (P &lt; 0.0001).

HER2 enriched score determined by using the expression levels of 3 genes (HER2, GRB7, MLN64) identified 35% (44/124) of the samples to be HER2 enriched. 72% of these (32/44) were also clinical HER2 positive by IHC. As expected, miR-21 was significantly over expressed in these tumors as well (P&lt;0.0001).

To identify all samples which might show HER2 downstream activity, a logistic regression model was built using expression of miR-21, HER2, MLN64 and GRB7 as the determinants of HER2 status. The best fitting model classified 91% (38/42) of HER2 +, 95% (59/62) of the HER2 negative accurately with 94% specificity and an AUC of 0.96. The model helped identify 10% of clinical HER2 negative samples (6/20 equivocal & 3/62 HER-2 negative) to have a high probability of being HER2+.

Conclusion: Identification of HER2+ tumors with evidence of downstream activity may help identify patients with tumors being driven significantly by HER2 from ones where its role is supportive. The possibility of targeting miR-21 raises the tantalizing prospect of effecting change by altering the epigenetic regulation of multiple targets including tumor-suppressors.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-07-09.

Estrogen Receptor Negative Breast Cancer in India: Do We Really Have Higher Burden of this Subtype?

ER negative and Triple negative breast cancers carry a poorer prognosis and are not amenable to hormone therapy. It has been previously observed that Indian patients with breast cancer have a higher tendency to have these tumours. Whether this is due to inherent biological differences in the tumours of our patients is a matter of much debate. We have analysed 250 patients of breast cancer for hormone receptor status, compared them with western series, and attempted to support the hypothesis that the higher ER negativity and triple negativity is indeed due to different tumour biology.

Abstract P5-03-03: DNA Methylation of the Estrogen Receptor (alpha) Promoter Is Higher in Triple Negative Breast Cancers Compared to the ER Negative Sub-Type

Background: The incidence of Estrogen Receptor alpha (ER) negative breast cancer and triple negative cases in India is twice that of Western Caucasians. The underlying causes for this two fold difference are unclear. DNA methylation of the ER promoter is one of the mechanisms of gene silencing. Recent data from the West indicate that the ER promoter is weakly methylated in a majority of patients independent of ER status. Data from an Indian cohort found 66% of ER negative breast tumors to be methylated at the ER gene. However, the technique used, Methylation specific PCR (MSP) suffers from a number of disadvantages such as false priming and low specificity. We have checked the methylation status of ER promoter A by a quantitative method and correlated it with clinicopathological parameters such as ER, progesterone receptor (PR) and Her2 protein status.

Materials and Methods: Tumor sections from 51 cases of primary invasive carcinomas were used for DNA extraction and bisulphite conversion. We adopted a quantitative method, Methylight assay for estimating the methylation status of the ER gene. Percentage Methylation Ratio (PMR) was computed and graded according to previously published standards. Methylation specific PCR was done for all these samples for comparison. Grade and Lymph node (LN) status were assessed. Immunohistochemistry was done to examine the status of ER, PR and Her2 protein.

Results: 16.6% of the ER negative tumors were moderately methylated (PMR score 5-50) at the ER promoter while none of the ER positive tumors were methylated to the same extent. Among the Triple Negative (TN) tumors in our cohort, 25% were moderately methylated. MSP tends to overestimate the methylated tumors and indicated that 43.5% of the ER negative tumors and19.2% of ER positive tumors were methylated. Discussion: A subgroup of ER negative and triple negative Indian patients have enhanced methylation of the ER gene. However this does not account for the doubling of ER negative incidence. Our demographics of a large pre-menopausal population might explain some part of this increase. Methylation of ER promoter was highest in TN tumors. This finding hints towards epigenetic dysregulation being a trait of TN tumors. The possibility of reversing the ER status from negative to positive in the clinic has raised an interest in the mechanism by which ER is lost.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-03-03.

Gene-specific methylation: potential markers for colorectal cancer

PURPOSE

Aberrant methylation of the promoter region is associated with silencing of many genes in neoplasia. CpG island methylation is an epigenetic mechanism for transcriptional silencing that occurs at various stages of colon tumorigenesis. In this study, we tested the promoter methylation and expression of seven genes from various pathways of DNA repair, apoptosis and inflammation, i.e., sFRP1, MLH1, RASSF1A, CDA, v-fgr, LYN-B, and TNFR10d.

METHOD

The genes were analyzed by quantitative polymerase chain reaction for the level of gene expression. The promoter methylation status of the genes was studied by methylation-specific polymerase chain reaction.

RESULT

The correlation of promoter methylation status with suppressed gene expression patterns suggested a potential role for the silencing these genes in colon cancer progression.

CONCLUSION

Promoter methylations of the studied genes could be explored as promising biomarkers for new diagnostic, prognostic and therapeutic targets of colorectal cancer.

Assessment of microsatellite instability in colorectal carcinoma at an Indian center

AIM

The purpose of the present study was to evaluate the frequency of microsatellite instability (MSI) in colorectal cancers in an Indian cohort.

MATERIALS AND METHODS

Paraffin embedded tissue samples of colorectal cancers from 46 patients were assessed for mismatch repair protein expression (hMLH1 and hMSH2) by immunohistochemistry. Subsequently, MSI analysis was done after PCR amplification of five Bethesda markers.

RESULTS

Amongst 46 cases studied, only 5 patients (10.8%) showed MSI. Out of these, two (4.3%) had high microsatellite instability (MSI-H) and three (6.5%) showed low microsatellite instability (MSI-L). Out of 46 cases, 41 were microsatellite stable (MSS). In the 46 cases tested by immunohistochemistry, 7 (15.7%) showed the absence of hMLH1 and 1 case showed the absence of hMSH2.

CONCLUSION

Our study indicates a similar rate of incidence of MSI in colorectal cancers in the Indian cohort compared to the West (10-15%) despite lower incidence of colorectal cancers and predominance of rectosigmoid tumors in the Indian population.