ßhCG mediates immune suppression through upregulation of CD11b+ Gr1+ myeloid derived suppressor cells, CD206+ M2 macrophages, and CD4+ FOXP3+ regulatory T-cells in BRCA1 deficient breast cancers.

BRCA1 mutation is reported in about 70% of all triple negative breast cancers (TNBC), while BRCA1 defect due to promoter hypermethylation is seen in about 30%-60% of sporadic breast cancers. Although PARP inhibitors and platinum-based chemotherapy are used to treat these cancers, more efficient therapeutic approaches are required to overcome the resistance to treatment. Our previous findings have reported elevated ßhCG expression but not αhCG in BRCA1 deficient breast cancers. As ßhCG causes immune suppression in pregnancy, this study explored the immunomodulatory effect of ßhCG in BRCA1mutated/deficient TNBC. We observed that Th1, Th2, and Th17 cytokines are upregulated in the presence of ßhCG in BRCA1 defective cancers. In NOD-SCID and syngeneic mouse models, ßhCG increases the frequency of Myeloid-derived suppressor cells in tumour tissues and contributes to macrophage reprogramming from antitumor M1 to pro-tumour M2 phenotype. ßhCG reduces the CD4+ T-cell infiltration while increasing the density of CD4+ CD25+ FOXP3+ regulatory T-cell in BRCA1 deficient tumour tissues. In contrast, xenograft tumours with ßhCG knocked down TNBC cells did not show these immune suppressive effects. We have also shown that ßhCG upregulates pro-tumorigenic markers arginase1(Arg1), inducible nitric oxide synthase, PD-L1/PD-1, and NFκB in BRCA1 defective tumours. Thus, for the first time, this study proves that ßhCG suppresses the host antitumor immune response and contributes to tumour progression in BRCA1 deficient tumours. This study will help develop new immunotherapeutic approaches for treating BRCA1 defective TNBC by regulating ßhCG.

Dry eye module - An application intelligence platform for diagnosing and monitoring dry eye disease.

Dry Eye Module (DEM), a software application, was developed to facilitate the streamlining of dry eye evaluation and documentation, to unify diagnostic jargon, and to analyze data input to generate a dry eye diagnostic report. This diagnostic report generated is based on the current understanding of dry eye diagnostic algorithms (Dry Eye Workshop 2 [DEWS2]/Asia Dry Eye Society [ADES]). Apart from its plausible role in aiding unprecedented multicentric dry eye demographic data collection, the application software can generate a customized referral letter to the rheumatologist, highlighting the salient ophthalmic features to be shared. DEM uses schematic illustrations to depict eyelid, conjunctival, and corneal parameters that impact the ocular surface in dry eyes that can be captured and compared during serial visits. Furthermore, DEM displays a symptom sign trend chart that graphically represents improvement/stability or worsening of the subjective and objective dry eye status. DEM can generate a curated prescription using preloaded advice templates. DEM includes facility for state-of-the-art advanced dry eye diagnostic reporting for super specialty use. The addition of DEM to the dry eye diagnostic armamentarium would help bridge the current unmet needs of dry eye evaluation. These are lack of uniform reporting, lack of multicentric data on a unified platform, the inability to ensure complete evaluation, inability to avoid lacunae during follow-up visits, and the lack of a simple patient-ophthalmologist and an ophthalmologist-rheumatologist interface.

Modulation of BRCA1 mediated DNA damage repair by deregulated ER-α signaling in breast cancers.

BRCA1 mutation carriers have a greater risk of developing cancers in hormone-responsive tissues like breasts and ovaries. However, this tissue-specific incidence of BRCA1 related cancers remains elusive. The majority of the BRCA1 mutated breast cancers exhibit typical histopathological features of high-grade tumors, with basal epithelial phenotype, classified as triple-negative molecular subtype and have a higher percentage of DNA damage and chromosomal abnormality. Though there are many studies relating BRCA1 with ER-α (Estrogen receptor-α), it has not been reported whether E2 (Estrogen) -ER-α signaling can modulate the DNA repair activities of BRCA1. The present study analyzes whether deregulation of ER-α signaling, arising as a result of E2/ER-α deficiency, could impact the BRCA1 dependent DDR (DNA Damage Response) pathways, predominantly those of DNA-DSB (Double Strand break) repair and oxidative damage response. We demonstrate that E2/E2-stimulated ER-α can augment BRCA1 mediated high fidelity repairs like HRR (Homologous Recombination Repair) and BER (Base Excision Repair) in breast cancer cells. Conversely, a condition of ER-α deficiency itself or any interruption in ligand-dependent ER-α transactivation resulted in delayed DNA damage repair, leading to persistent activation of γH2AX and retention of unrepaired DNA lesions, thereby triggering tumor progression. ER-α deficiency not only limited the HRR in cells but also facilitated the DSB repair through error prone pathways like NHEJ (Non Homologous End Joining). ER-α deficiency associated persistence of DNA lesions and reduced expression of DDR proteins were validated in human mammary tumors.

Evaluation of genoprotection against malathion induced toxicity by Orthosiphon thymiflorus Sleesen.

BACKGROUND: Pesticide toxicity is considered to be one of the significant reason for increased incidence of cancer. Plants are treasure troves of active phytochemical compounds which are used as herbal medicine as well as nutraceuticals. OBJECTIVE: To evaluate the genoprotective potential of Orthosiphon thymiflorus (Roth) Sleesen, (Lamiaceae) against the toxicity induced by malathion by a battery of four in vivo assays in Swiss albino mice. MATERIALS AND METHODS: Micronucleus assay was performed for analyzing the micronuclei induction and ratio of polychromatic and normochromatic erythrocytes (PCE/NCE). Anticlastogenic and mito depressive effect of the methanol and hexane extracts of O.thymiflorus were evaluated by chromosome aberration assay. Alkali comet assay was performed to assess double strand DNA repair. DNA damage sensing ability of the bone marrow cells were assessed by γ-H2AX foci formation. Phytochemical screening of hexane and methanol extract was done by GC-MS analysis. RESULT: O. thymiflorus extracts showed a dose dependant protective effect in all assays. It significantly decreased the frequency of micronuclei and improved PCE/NCE value in post treated groups of animals. Malathion induced clastogenic aberrations were effectively attenuated by methanol and hexane extracts. DNA comet assay showed that malathion induced damage can be protected by O. thymiflorus extracts. Multiple foci formation in γ-H2AX assay confirmed the activation of DNA repair proteins in post treated animals. CONCLUSION: Genoprotective effect of O. thymiflorus against malathion induced toxicity was confirmed. This study would be helpful to initiate more research including clinical using O. thymiflorus extract against pesticide induced toxicity.

Perspectives on mechanistic implications of ROS inducers for targeting viral infections.

In this perspective, we propose to leverage reactive oxygen species (ROS) induction as a potential therapeutic measure against viral infections. Our rationale for targeting RNA viral infections by pro-oxidants is routed on the mechanistic hypothesis that ROS based treatment paradigm could impair RNA integrity faster than the other macromolecules. Though antiviral drugs with antioxidant properties confer potential abilities for preventing viral entry, those with pro-oxidant properties could induce the degradation of nascent viral RNA within the host cells, as RNAs are highly prone to ROS mediated degradation than DNA/proteins. We have previously established that Plumbagin is a highly potent ROS inducer, which acts through shifting of the host redox potential. Besides, it has been reported that Plumbagin treatment has the potential for interrupting viral RNA replication within the host cells. Since the on-going Corona Virus Disease - 2019 (COVID-19) global pandemic mediated by Severe Acute Respiratory Syndrome Corona Virus-2 (SARS-CoV-2) exhibits high infectivity, the development of appropriate antiviral therapeutic strategies remains to be an urgent unmet race against time. Therefore, additional experimental validation is warranted to determine the appropriateness of repurposable drug candidates, possibly ROS inducers, for fighting the pandemic which could lead to saving many lives from being lost to COVID-19.

Deregulated estrogen receptor signaling and DNA damage response in breast tumorigenesis.

Carriers of BRCA1 mutations have a higher chance of developing cancers in hormone-responsive tissues like the breast, ovary and prostate, compared to other tissues. These tumors generally exhibit basal-like characters and do not express estrogen receptor (ER) or progesterone receptor (PR). Intriguingly, BRCA1 mutated breast cancers have a less favorable clinical outcome, as they will not respond to hormone therapy. BRCA1 has been reported to exhibit ligand dependent and independent transcriptional inhibition of ER-α; however, there exists a controversy on whether BRCA1 induces or inhibits ER-α expression. The mechanisms associated with resistance of BRCA1 mutated cancers to hormone therapy, as well as the tissue restriction exhibited by BRCA1 mutated tumors are still largely unknown. BRCA1 mutated tumors possess increased DNA damages and decreased genomic integrity, as BRCA1 plays a cardinal role in high fidelity DNA damage repair pathways, like homologous recombination (HR). The existence of cross regulatory signaling networks between ER-α and BRCA1 speculates a role of ER on BRCA1 dependent DDR pathways. Thus, the loss or haploinsufficiency of BRCA1 and the consequential deregulation of ER-α signaling may result in persistence of unrepaired DNA damages, eventually leading to tumorigenesis. Therefore, understanding of this cross-talk between ER-α and BRCA1, with regard to DDR, will provide critical insights to steer drug development and therapy for breast/ovarian cancers. This review discusses the mechanisms by which estrogen and ER signaling influence BRCA1 mediated DNA damage response and repair pathways in the mammalian system.

RTKs in pathobiology of head and neck cancers.

Non-communicable diseases contribute to 71% of the deaths worldwide, of which cancers rank second after cardiovascular diseases. Among all the cancers, head and neck cancers (HNC) are consequential in augmenting the global cancer incidence as well as mortality. Receptor tyrosine kinases (RTKs) are emphatic for the matter that they serve as biomarkers aiding the analysis of tumor progression and metastasis as well as diagnosis, prognosis and therapeutic progression in the patients. The extensive researches on HNC have made significant furtherance in numerous targeted therapies, but for the escalating therapeutic resistance. This review explicates RTKs in HNC, their signaling pathways involved in tumorigenesis, metastasis and stemness induction, the association of non-coding RNAs with RTKs, an overview of RTK based therapy and associated resistance in HNC, as well as a sneak peek into the HPV positive HNC and its therapy. The review extrapolates the cardinal role of RTKs and RTK based therapy as superior to other existing therapeutic interventions for HNC.

Gene expression signatures: A tool for analysis of breast cancer prognosis and therapy.

Breast Cancer is the most predominant female cancer in developed as well as developing countries. The treatment strategies of breast cancers depends on an array of factors like age at diagnosis, menstrual status, dietary pattern, immunological response, genetic variations of the cancer cells etc. Recent technological advancements in cancer diagnosis lead to the emergence of gene expression pattern for better understanding of the tumor behavior. It has not only bolstered the prognosis, but also the early diagnosis and therapy. The accuracy in disease prognosis can be boosted when gene expression signatures are combined with traditional clinicopathological features. This review explains how the evolution of gene expression signatures for breast cancers, its advantages and future prospects. In addition, an overview of currently available gene expression signature analysis tools and consolidated information on their current status and specific benefits, that can be availed for breast cancer diagnosis are also discussed.

BRCA1 promoter hypermethylation in human placenta: a hidden link with ß-hCG expression.

Gestational trophoblastic diseases (GTD) are group of pregnancy-related tumors characterized by abnormal levels of 'ß-hCG' with higher incidence in South-East Asia, especially India. Our laboratory has reported that wild-type BRCA1 transcriptionally regulates ß-hCG in triple negative breast cancers (TNBCs). These factors culminated into analysis of BRCA1 status in GTD, which would emanate into elucidation of BRCA1- ß-hCG relationship and unraveling etio-pathology of GTD. BRCA1 level in GTD is down-regulated due to the over-expression of DNMT3b and subsequent promoter hypermethylation, when compared to the normal placentae accompanied with its shift in localization. There is an inverse correlation of serum ß-hCG levels with BRCA1 mRNA expression. The effects of methotrexate (MTX), which is the first-line chemotherapeutic used for GTD treatment, when analyzed in comparison with plumbagin (PB) revealed that PB alone is efficient than MTX alone or MTX-PB in combination, in showing selective cytotoxicity against GTD. Interestingly, PB increases BRCA1 levels post-treatment, altering DNMT3b levels and resultant BRCA1 promoter methylation. Also, cohort study analyzed the incidence of GTD at Sree Avittom Thirunal (SAT) Hospital, Thiruvananthapuram, which points out that 11.5% of gestational trophoblastic neoplasia (GTN) cases were referred to Regional Cancer Centre, Thiruvananthapuram, for examination of breast lumps. This has lend clues to supervene the risk of GTD patients towards BRCA1-associated diseases and unveil novel therapeutic for GTD, a plant-derived naphthoquinone, PB, already reported as selectively cytotoxic against BRCA1 defective tumors.

Cytological Grading of Breast Tumors-The Human and Canine Perspective.

Human breast cancers (HBCs) are one of the leading causes of global cancer death among women. Domesticated canines are the most affected domestic species with a prevalence rate of breast cancer more than three times in women. While the human cancer patients receive substantial diagnostic and treatment facilities, inadequacy in canine cancer care, calls for greater attention. Fine Needle Aspiration Cytology (FNAC) is comparatively simple, quick, and easily reproducible technique, which aids in pre-surgical diagnosis. In humans, FNAC has a standard protocol, the Robinson's grading system, which has high correlation with the established histological grading system of Scarff Bloom- Richardson. However, Canine Mammary Tumors (CMTs), which are known to be similar to HBCs in biological behavior and gene expressions, still bank on the histopathological methods for diagnostic purposes. This review sheds light on various factors that could be considered for developing a standard FNAC technique for CMT grading and analyzes its future perspectives.

ß-hCG-induced mutant BRCA1 ignites drug resistance in susceptible breast tissue.

ß-hCG expression in breast cancer is highly controversial with reports supporting both protective and tumorigenic effects. It has also been reported that risk of breast cancer at an early age is increased with full-term pregnancies if a woman is a BRCA1 mutation carrier. We have already demonstrated that BRCA1-defective cells express high levels of ß-hCG and that when BRCA1 is restored, ß-hCG level is reduced. Also, BRCA1 can bind to the promoter and reduce the levels of ß-hCG. ß-hCG induces tumorigenicity in BRCA1-defective cells by directly binding to TGFBRII and induces TGFBRII-mediated cell proliferation. In this study, we analyzed the mechanism of action of ß-hCG on BRCA1 expression and its influence on drug sensitivity in breast cancer cells. We demonstrate that ß-hCG induces mutant BRCA1 protein expression in BRCA1 mutant cells; however, in BRCA1 wild-type cells, ß-hCG reduced wild-type BRCA1 protein expression. Transcriptionally, ß-hCG could induce Slug/LSD1-mediated repression of wild-type and mutant BRCA1 messenger RNA levels. However, ß-hCG induces HSP90-mediated stabilization of mutant BRCA1 and hence the overexpression of mutant BRCA1 protein, resulting in partial restoration of homologous recombination repair of damaged DNA. This contributes to drug resistance to HSP90 inhibitor 17AAG in BRCA1-defective cancer cells. A combination of HSP90 inhibitor and TGFBRII inhibitor has shown to sensitize ß-hCG expressing BRCA1-defective breast cancers to cell death. Targeting the ß-hCG-HSP90-TGFBRII axis could prove an effective treatment strategy for BRCA1-mutated breast tumors.

Brcal Defective Breast Cancer Cells Induce in vitro Transformation of Cancer Associated Fibroblasts (CAFs) to Metastasis Associated Fibroblasts (MAF).

It is known that Cancer Associated Fibroblast (CAFs) from the primary tumor site can accompany cancer cells to a secondary site during the process of metastasis. We hypothesize that these CAFs could be transformed to an altered cell type, which can be called as Metastasis Associated Fibroblasts (MAF) in turn can support, and convoy cancer cells for metastasis. There are no published reports that have characterized and distinguished CAFs from MAF. It is well established that some of the cancer cells within the tumor mass accumulate novel mutations prior to metastasis. Hence, we speculated that mutations in the tumor suppressor gene, BRCA1, which is already reported to induce metastasis via abnormal expression of Ezrin, Radixin and Moesin (ERM), could generate MAF. In the present study, we demonstrate for the first time that CAFs isolated from primary breast cancer tissues when co-cultured with BRCA1 mutated HCC1937 cells transform CAFs to MAF in vitro. As expected, MAF augmented proliferation, migration and invasion along with over-expression of epithelial mesenchymal transition (EMT) markers, Ezrin and CCL5, thereby facilitating metastasis. Therefore, we inhibited Ezrin and CCL5 in vitro in MAF and observed that the migration and invasion abilities of these cells were attenuated. This highlights the intriguing possibilities of combination therapy using MAF inhibitors as anti-metastatic agents along with anticancer drugs, to control the metastatic spread from primary tumor site.

NCI Summer Curriculum in Cancer Control and Prevention ­ A Practice Changing Course for Oncologists from Limited Resource Country Like India

Cancer has become an important public health issue in India. Oncologists in India spends most of their time in diagnosis and treatment of cancer patients. There is a large disparity geographically as far as cancer treatment facilities are concerned. Cancer control and cancer prevention is not a point of concern for most of the practicing oncologist. Although things are changing in India, but orientation, passion and dedication towards cancer prevention is still missing. There is no program on basic principles and practice of cancer control and prevention in India which addresses the essence of cancer control and prevention. Center for Global Health of National Cancer Institute, USA initiated summer curriculum is an excellent academic program to teach health care professionals working in cancer care in different parts of world. This covers all aspect of cancer care i.e. cancer education, epidemiology, screening, diagnosis, treatment and the before world palliative care with dedicated session on upcoming molecular prevention in cancer. This gives an unique opportunity for learning and can be practice changing curriculum for many of the attendees who want to pursue a career in cancer control and prevention a before practice.

Regulation of epithelial to mesenchymal transition by BRCA1 in breast cancer.

Reports till its discovery has proven multiple facets of Breast Cancer type 1 susceptibility gene (BRCA1) from nucleus to cytoplasm; from DNA repair to drug resistance; from Homologous Recombination (HR) to Ubiquitination; from breast to brain; from cancer to HIV and many of the roles are still unexplored. One of the recent attractions of BRCA1 is its role in regulating breast cancer metastasis though the exact mechanism is poorly understood. In this review, we will discuss the molecular interactions between BRCA1 and the key molecules of Epithelial to Mesenchymal Transition (EMT) associated with metastasis, its associated drug resistance and the possible treatment strategy for BRCA1 mutated breast cancer.

Proteomic Profiling of ß-hCG-Induced Spheres in BRCA1 Defective Triple Negative Breast Cancer Cells.

Previously, we identified that ß-hCG is expressed by BRCA1 mutated but not wild type breast cancers in vitro/in vivo and exhibited a novel event in ß-hCG overexpressing BRCA1 mutated HCC1937 cells where the cells were able to form spheres (HCC1937 ß spheres) in adherent cell culture plates even in the absence of any growth factors. These spheres express stem cell and EMT markers. In the present study, we carried out the total proteomic profiling of these HCC1937 ß spheres obtained from BRCA1 defective ß-hCG expressing stable breast cancer cells to analyze the cell signaling pathways that are active in these cells. Functional annotation revealed proteins (164 cellular and 97 secretory) predominantly involved in oxygen binding, nucleosome assembly, cytoskeleton organization, protein folding, etc. Many of the proteins identified from HCC1937 ß spheres in this study are also up regulated in breast cancers, which are directly linked with poor prognosis in human cancer samples as analyzed using TCGA data set. Survival analysis shows that ß-hCG expressing cancer patients are linked with poor survival rate. Interestingly, hemoglobins were identified at both cellular and secretory level in HCC1937 ß spheres and experiments after treating with ROS inducers revealed that ß-hCG induces hemoglobin and protects the cancer cells during oxidative stress. Our proteomic data strongly propose ß-hCG as an oncogenic molecule associated with BRCA1 mutation, and hence, targeting ß-hCG could be a strategy to treat BRCA1 defective breast cancers.

Insights into dovetailing GTD and Cancers.

Gestational trophoblastic diseases (GTD) encompass a group of placental tumors which mostly arise due to certain fertilization defects, resulting in the over-proliferation of trophoblasts. The major characteristic of this diseased state is that ß-hCG rises up manifold than that is observed during pregnancy. The incidence of GTD when analyzed on a global scale, figures out that there is a greater risk in South-East Asia, the reason of which remains unclear. An insight into any possible correlation of GTD incidence with cancers, other than choriocarcinoma, is being attempted here. Also, we review the recent developments in research on the molecular etiopathology of GTD. This review would render a wider eye towards a new paradigm of thoughts to connect GTD and breast cancer, which has not been into the picture till date.

Molecular trail for the anticancer behavior of a novel copper carbohydrazone complex in BRCA1 mutated breast cancer.

Novel chelated metal complexes were synthesized from carbohydrazones to thiocarbohydrazones using metal-based drug designing platforms and their combination effect with Pb, a naphthaquinone were analyzed for anticancer activity in breast cancer cell lines. A panel of BRCA1 wild-type and mutated breast cancer cells: MCF-7 (BRCA1+ /ER+ ), MDA-MB-231 (BRCA1+ /ERα- ), HCC-1937 (BRCA1- /ERα- ), HCC1937/wt BRCA1, MX1 (BRCA1- /ERα- ), and MDA-MB-436 (BRCA1- /ERα- ) were screened for anti-cancer activity. Cu2 (HL)(HSO4 ) · H2 O]SO4 · 6 H2 O (CS2) is the most potent anticancer agent among the copper carbohydrazone and thiocarbohydrazone complexes analyzed in this study. It can be suggested that the presence of sulphate, as pharmacologically active centre, can induce cytotoxicity more effectively when compared to chlorine, bromine, perchlorate, and methanol. This is the first report demonstrating that CS2 can bind to DNA by hindering BamH1 activity and could induce DNA double strand breaks as evidenced by γ-H2AX expression. In addition to this, CS2 could also act as a Topo II inhibitor at a much lower concentration than etoposide and induce apoptosis, making it a potent anticancer agent. In combination with Pb, a potent ROS inducer, CS2 could induce synergistic anti-cancer activity in HR/ BRCA1 defective breast cancer cells. This is the first study reporting the mechanism involved in the induction of apoptosis for a metal chelated copper carbohydrazone complex and its combination effects with Pb in HR defective, BRCA1 mutated breast cancer cells.

The prodigious network of chromosome 17 miRNAs regulating cancer genes that influence the hallmarks of cancer.

Chromosome 17 (Chr17) harbors crucial genes that encode proteins implicated in a variety of cancers, including some that guard cancer cells from genomic instability and others that interfere with metastasis. Included amongst the genes on chr17 that regulate biological processes fundamental to the genesis of cancer are TP53, BRCA1, CCL5, NF-1, and GRB7. As many as 50% of all human tumors and at least 30% of breast carcinomas contain p53 mutations, while 30%-40% of breast cancers have defective BRCA1. A large number of proteins regulate the expression of these cancer genes on chr17 with miRNAs, the most widely studied class of regulatory RNAs, playing a major role in epigenetically controlling the gene expression programs, thereby managing various cellular functions. This review provides information on the genes transcribed from chr17, and their regulation by miRNAs in the context to tumorigenesis located on chr17, along with an analysis of the receptor status (estrogen, progesterone, and Her2/Neu) from the miRNA prediction data of miRNA genes located on chr17.

Selective mode of action of plumbagin through BRCA1 deficient breast cancer stem cells.

BACKGROUND: Studies over the past decade and half have identified cancer stem cells (CSCs) to be responsible for tumorigenesis, invasion, sustenance of metastatic disease, radio- and chemo-resistance and tumor relapse. Recent reports have described the plasticity of breast CSCs (BCSCs) to shift between the epithelial and mesenchymal phenotypes via Epithelial-Mesenchymal Transition (EMT) and Mesenchymal-Epithelial Transition (MET) states as the reason for their invasive capabilities. Additionally, BRCA1 has been found to be a mammary stem cell fate determinant. However, it is not clear what would be the best marker that can be used for identifying CSCs in BRCA1 mutated cancers. Also, anticancer agents that can reduce CSC population in a BRCA1 defective condition have not been addressed so far. METHODS: Putative BCSCs were identified based on Hoechst exclusion, CD44(+)/24(-/low) expression and Aldehyde Dehydrogenase 1 (ALDH1) positivity using flow cytometry. The 'stemness' of the isolated ALDH1+ cells were analysed by immunofluorescence, western blotting for stem cell and EMT markers as well as in vitro mammosphere assays. Induction of Reactive Oxygen Species (ROS) by Plumbagin (PB) in BCSCs was assayed by Dichloro-dihydro-fluorescein diacetate (DCF-DA) staining. Ovarian cancer xenografts treated with PB were subjected to immunohistochemical analysis to study the ability of PB to target CSCs. RESULTS: We have confirmed that ALDH1 positivity is the best marker for the identification of BCSCs in BRCA1-defective breast cancer cell lines when compared to the CD marker profile and Side Population (SP) analysis. BRCA1 status was observed to be a determinant of the abundance of epithelial-like (ALDH1+) or mesenchymal-like (CD44(+)/24(-/low)) BCSCs, and the reconstitution of a full length, wild type BRCA1 in HCC1937 breast cancer cells possessing a mutated BRCA1, transforms them from 'stem-like' to more 'mesenchymal'. For the first time we have shown that Plumbagin (PB), a naturally occurring naphthoquinone which is predominantly a ROS inducer, could reduce BCSCs specifically in BRCA1-defective, basal-like cancer cells. CONCLUSIONS: The best marker for identifying BCSCs in BRCA1 defective condition could be ALDH1 and that BRCA1 mutated BCSCs would be mostly 'stem like' than 'mesenchymal'. Also ROS inducers like PB could reduce BCSCs in BRCA1 defective cancers.