Schleichera oleosa Seed Extract Reduced the Proliferation of Breast Cancer by Regulating the BRCA1 and p16 Genes.

BACKGROUND: Breast cancer is the most commonly diagnosed cancer and the leading cause of cancer death in females worldwide. Schleichera oleosa (kusum tree) belongs to the Sapindaceae family commonly found in many states of India. This plant is traditionally being used in various pathological conditions. METHODS: In vitro studies were performed using seed extract of Schleichera oleosa. Different concentrations of seed extracts were treated on MCF-7 breast cancer cell line and its effect on migration and colony formation were observed. BRCA1 and p16 gene expression was analyzed by real-time PCR and Western blotting. RESULTS: We have analyzed anticancer and anti-metastatic effects of seed extract in breast cancer and IC50 was 140µg/ml concentration. Further, its inhibitory role in cell migration and colony formation was at 140µg/ml (P<0.0001) concentration and reduced significantly growth of sphere at 140 µg (P<0.0031) and 150µg (P<0.0010) concentration after 5 days of treatment. The apoptosis study was shown a significant increase at 140 µg (P<0.0001) in apoptotic cells. Expression of BRCA1 and p16 were found to be over-expressed as 1.4 and 1.7 fold, respectively, at 140µg/ml concentration after 24 h of treatment at the transcription level. BRCA1 protein was up-regulated but p16 expression down-regulated at 140 to 150µg/ml (One-Way ANOVA, P<0.0001) concentration. CONCLUSION: In this study, we found a significant role of S. Oleosa seed extract has an anti-cancer as well as anti-metastatic via up-regulation of BRCA1 and p16 genes in breast cancer cells.

VEGF pathway inhibition potentiates PARP inhibitor efficacy in ovarian cancer independent of BRCA status.

Poly ADP-ribose polymerase inhibitors (PARPi) have transformed ovarian cancer (OC) treatment, primarily for tumours deficient in homologous recombination repair. Combining VEGF-signalling inhibitors with PARPi has enhanced clinical benefit in OC. To study drivers of efficacy when combining PARP inhibition and VEGF-signalling, a cohort of patient-derived ovarian cancer xenografts (OC-PDXs), representative of the molecular characteristics and drug sensitivity of patient tumours, were treated with the PARPi olaparib and the VEGFR inhibitor cediranib at clinically relevant doses. The combination showed broad anti-tumour activity, reducing growth of all OC-PDXs, regardless of the homologous recombination repair (HRR) mutational status, with greater additive combination benefit in tumours poorly sensitive to platinum and olaparib. In orthotopic models, the combined treatment reduced tumour dissemination in the peritoneal cavity and prolonged survival. Enhanced combination benefit was independent of tumour cell expression of receptor tyrosine kinases targeted by cediranib, and not associated with change in expression of genes associated with DNA repair machinery. However, the combination of cediranib with olaparib was effective in reducing tumour vasculature in all the OC-PDXs. Collectively our data suggest that olaparib and cediranib act through complementary mechanisms affecting tumour cells and tumour microenvironment, respectively. This detailed analysis of the combined effect of VEGF-signalling and PARP inhibitors in OC-PDXs suggest that despite broad activity, there is no dominant common mechanistic inter-dependency driving therapeutic benefit.

Anti-Müllerian Hormone (AMH) regulates BRCA1 and BRCA2 gene expression after ovarian cortex transplantation.

OBJECTIVE: To test whether recombinant anti-Müllerian hormone (rAMH) could exert an inhibitory function on BRCA1/2 expression in human ovarian cortex. METHODS: Pilot study on ovariectomized nude mice xenotransplanted with human vitrified/warmed ovarian cortex and treated with rAMH via infusion pump. Twelve nude mice were ovariectomized and Alzet pumps delivering 1.23 mcg rAMH/day to reach a serum concentration of 17.5 ng/mL, or placebo (controls), were inserted intraabdominally. Previously vitrified/warmed 2x2 mm ovarian cortex fragments were transplanted on day 7 and then harvested on day 14 after pump placement. PCR analyses determined mRNA levels for BRCA1 and BRCA2 in the human ovarian cortex. RESULTS: In mice treated with rAMH, BRCA1 expression was significantly lower (0.196 fg/µg RNA, IQR 0.158, 0.236) than in controls (0.544 fg/µg RNA, IQR 0.458, 0.554; p = .030), while BRCA2 expression remained similar in rAMH mice (5.355 fg/µg RNA, IQR 4.479, 6.230) and in controls (4.011 fg/µg RNA, IQR 3.650, 4.182; p = .327). CONCLUSION: Administration of rAMH in the peri-transplant period caused downregulation of BRCA1, but not of BRCA2 expression, in human ovarian cortex. These results help our understanding of DNA repair mechanism in the ovarian cortex and identify AMH's possible protective effect on ovarian reserve in BRCA1 mutation carriers.

Biomarker-Guided Development of DNA Repair Inhibitors.

Anti-cancer drugs targeting the DNA damage response (DDR) exploit genetic or functional defects in this pathway through synthetic lethal mechanisms. For example, defects in homologous recombination (HR) repair arise in cancer cells through inherited or acquired mutations in BRCA1, BRCA2, or other genes in the Fanconi anemia/BRCA pathway, and these tumors have been shown to be particularly sensitive to inhibitors of the base excision repair (BER) protein poly (ADP-ribose) polymerase (PARP). Recent work has identified additional genomic and functional assays of DNA repair that provide new predictive and pharmacodynamic biomarkers for these targeted therapies. Here, we examine the development of selective agents targeting DNA repair, including PARP inhibitors; inhibitors of the DNA damage kinases ataxia-telangiectasia and Rad3 related (ATR), CHK1, WEE1, and ataxia-telangiectasia mutated (ATM); and inhibitors of classical non-homologous end joining (cNHEJ) and alternative end joining (Alt EJ). We also review the biomarkers that guide the use of these agents and current clinical trials with these therapies.

Hormonal contraceptives and breast cancer: Clinical data.

The endocrine background of breast cancer has raised questions about the increase in risk that might bear the use of hormonal contraceptives. This has been a particular issue in the case of young women, who constitute the population of contraceptive consumers. Observational studies have been the main source of evidence, which has mainly limited to the combined estrogen-progestogen preparations, the popular pill. Studies in the 80's and 90's of the past century found a small, around a 20%, increase in risk. The translation in absolute number of excess cases has been exiguous because the prevalence of the disease is relatively small in premenopausal women. Moreover, the risk slowly seemed to disappear after 5-10 years of use. The more sophisticated analyses provided by new technologies, together with the powerful central registries in some countries, has confirmed increased risk of similar size. Recent preparations, with lower doses of estrogens and new progestogenic molecules, have not substantially modified the risk size. The impact of progestogen only alternatives, either pills or progestogen-loaded intrauterine devices, seems to be similar, but the evidence is still insufficient. Whether there is a preferential effect on histological or molecular subtypes of breast tumours is being debated yet. The data on women at higher risk, either with mutations of the BRCA1/2 genes or with familial weight, have not found specific response patterns, but the experience is still meagre. It is of interest that long-term follow up data on women who enrolled in the initial cohorts, like that of the Royal College of General Practitioners', have shown a considerable protection against cancer of the ovary (relative risk, RR 0.67), endometrium (RR 0.66), or colorectum (RR 0.81).

Curcumin activates DNA repair pathway in bone marrow to improve carboplatin-induced myelosuppression.

Carboplatin, a second-generation platinum agent, has been used as a cancer therapy for decades and exhibits strong anti-tumor activity. However, the wide application of carboplatin is largely limited due to its side effects, especially myelosuppression. Here, we combined carboplatin with curcumin, a natural product that improves tumor-induced anemia, for the treatment of fibrosarcoma to improve the side effects of carboplatin. We first examined the synergistic and attenuated effects of the two agents in a T241-bearing mouse model. The combination therapy caused no obvious synergistic effect, but curcumin significantly improved the survival rate of carboplatin-treated mice. Histologic analysis of the kidney and bone marrow revealed that curcumin improved carboplatin-induced myelosuppression but did not affect the kidney. To determine the mechanism involved, we introduced a probe derived from curcumin to identify its targets in bone marrow cells and the results provided us a clue that curcumin might affect the DNA repair pathway. Western blot analysis revealed that curcumin up-regulated BRCA1, BRCA2 and ERCC1 expression in bone marrow. In conclusion, curcumin attenuates carboplatin-induced myelosuppression by activating the DNA repair pathway in bone marrow cells.

Differential Cytotoxicity, Cellular Uptake, Apoptosis and Inhibition of BRCA1 Expression of BRCA1-Defective and Sporadic Breast Cancer Cells Induced by an Anticancer Ruthenium(II)-Arene Compound, RAPTA-EA1.

BACKGROUND: The RAPTA-EA1 complex [ruthenium(II)-arene 1,3,5-triaza-7-phosphaadamantane (pta) complex with an arene-tethered ethacrynic acid ligand] has been reported to overcome drug resistance that developed due to the current use of platinum-based treatments. However, the exact mechanism of action of RAPTA-EA1 remains largely unexplored and unknown. OBJECTIVE: Here we have further studied the effect of RAPTA-EA1 on BRCA1-defective HCC1937 breast cancer cells and compared its effects on BRCA1-competent MCF-7 breast cancer cells. METHOD: HCC1937 and MCF-7 breast cancer cells were treated with the RAPTA-EA1 complex. The cytotoxicity of ruthenium-induced cells was evaluated by a MTT assay. Cellular uptake of ruthenium was determined by ICP-MS. Cell cycle and apoptosis were assessed using a flow cytometer. Expression of BRCA1 mRNA and its encoded protein was quantitated by a real-time RT-PCR and Western blotting. RESULTS: Differences in cytotoxicity were correlated with the differential accumulations of ruthenium and the induction of apoptosis. The ruthenium complex caused dramatically more damage to the BRCA1 gene in the BRCA1-defective HCC1937 cells than to the BRCA1-competent MCF-7 cells. It decreased the expression of BRCA1 mRNA in the BRCA1-competent cells, while in contrast, its expression increased in the BRCA1-defective cells. However, the expression of the BRCA1 protein was significantly reduced in both types of breast cancer cells. CONCLUSION: The results presented here have demonstrated a differential cellular response for the BRCA1-defective and BRCA1-competent breast cancer cells to RAPTA-EA1. These findings have provided more insight into the actions and development of the ruthenium-based compounds for use for the treatment of breast cancer.

Assessing Heavy Metal and PCB Exposure from Tap Water by Measuring Levels in Plasma from Sporadic Breast Cancer Patients, a Pilot Study.

Breast cancer (BrCA) is the most common cancer affecting women around the world. However, it does not arise from the same causative agent among all women. Genetic markers have been associated with heritable or familial breast cancers, which may or may not be confounded by environmental factors, whereas sporadic breast cancer cases are more likely attributable to environmental exposures. Approximately 85% of women diagnosed with BrCA have no family history of the disease. Given this overwhelming bias, more plausible etiologic mechanisms should be investigated to accurately assess a woman's risk of acquiring breast cancer. It is known that breast cancer risk is highly influenced by exogenous environmental cues altering cancer genes either by genotoxic mechanisms (DNA mutations) or otherwise. Risk assessment should comprehensively incorporate exposures to exogenous factors that are linked to a woman's individual susceptibility. However, the exact role that some environmental agents (EA) play in tumor formation and/or cancer gene regulation is unclear. In this pilot project, we begin a multi-disciplinary approach to investigate the intersection of environmental exposures, cancer gene response, and BrCA risk. Here, we present data that show environmental exposure to heavy metals and PCBs in drinking water, heavy metal presence in plasma of nine patients with sporadic BrCA, and Toxic Release Inventory and geological data for a metal of concern, uranium, in Northeast Georgia.

BRCA1 as target for breast cancer prevention and therapy.

The Breast Cancer 1 protein (BRCA1) is a tumor suppressor involved in basic cellular functions necessary for cell replication and DNA synthesis, but reduced expression of BRCA1, due to mutations or epigenetic inactivation, leads to impaired mammary gland differentiation and increased risk of breast cancer development. Although BRCA1 acts as a tumor suppressor and is present in all cells, where it is essential for the maintenance of the genome integrity, it is still not clear why mutations in the BRCA1 gene predispose to breast and ovarian, but not to other types of cancer. In the first part of this review, we briefly discuss the function and regulation of the BRCA1 protein, including its role associated with familial and sporadic breast cancer. The second part is an overview of the therapeutic compounds used for breast cancer treatment targeting BRCA1, and the natural food components that hold potential preventive effect against those types of breast cancer in which BRCA1 expression is either reduced or lacking. Further studies elucidating the interactions between dietary compounds and cellular pathways, involved in regulation of BRCA1expression, are necessary for the development of strategies that may successfully prevent or treat breast cancer.

Gestational exposure to the AhR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin induces BRCA-1 promoter hypermethylation and reduces BRCA-1 expression in mammary tissue of rat offspring: preventive effects of resveratrol.

Studies with murine models suggest that maternal exposure to aromatic hydrocarbon receptor (AhR) agonists may impair mammary gland differentiation and increase the susceptibility to mammary carcinogenesis in offspring. However, the molecular mechanisms responsible for these perturbations remain largely unknown. Previously, we reported that the AhR agonists 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced CpG methylation of the breast cancer-1 (BRCA-1) gene and reduced BRCA-1 expression in breast cancer cell lines. Based on the information both the human and rat BRCA-1 genes harbor xenobiotic responsive elements (XRE = 5'-GCGTG-3'), which are binding targets for the AhR, we extended our studies to the analysis of offspring of pregnant Sprague-Dawley rats treated during gestation with TCDD alone or in combination with the dietary AhR antagonist resveratrol (Res). We report that the in utero exposure to TCDD increased the number of terminal end buds (TEB) and reduced BRCA-1 expression in mammary tissue of offspring. The treatment with TCDD induced occupancy of the BRCA-1 promoter by DNA methyltransferase-1 (DNMT-1), CpG methylation of the BRCA-1 promoter, and expression of cyclin D1 and cyclin-dependent kinase-4 (CDK4). These changes were partially overridden by pre-exposure to Res, which stimulated the expression of the AhR repressor (AhRR) and its recruitment to the BRCA-1 gene. These findings point to maternal exposure to AhR agonists as a risk factor for breast cancer in offspring through epigenetic inhibition of BRCA-1 expression, whereas dietary antagonists of the AhR may exert protective effects.

Use of fertility drugs and risk of ovarian cancer.

PURPOSE OF REVIEW: The purpose of this review is to highlight recent research and insights into the relationship between fertility drug use and ovarian cancer risk. RECENT FINDINGS: Results from two large case-control studies provided further evidence that fertility drug use does not significantly contribute to risk of ovarian cancer among the majority of women when adjusting for known confounding factors. However, questions regarding the effect on certain subgroups, including long-term fertility drug users, women who remain nulligravid after fertility treatment, women with BRCA1 or BRCA2 mutations and borderline ovarian tumours, still remain. In addition, it may currently just be too early to determine whether there is an association between fertility drug use and ovarian cancer risk given that many of the exposed women are only now beginning to reach the ovarian cancer age range. SUMMARY: Whether use of fertility drugs increases the risk of ovarian cancer is an important question that requires further investigation, in particular given the large number of women utilizing fertility treatments. Fortunately, results from recent studies have been mainly reassuring. Large well designed studies with sufficient follow-up time are needed to further evaluate the effects of fertility treatments within subgroups defined by patient and tumour characteristics.

[PARP inhibitors--theoretical basis and clinical application]. / Inhibitory PARP--podstawy teoretyczne i zastosowanie kliniczne.

Poly-ADP-ribose polymerases (PARP) are involved in a number of processes that are vital for every living cell. Once activated by the presence of DNA damage they trigger poly-ADP-ribosylation of various proteins which are crucial for DNA repair, preserving of genom integrity, regulation of transcription, proliferation and apoptosis. PARP1, which is the best known enzyme of PARP protein family, plays a role in single-strand breaks (SSB) repair. Decrease of its activity results in accumulation of single strand DNA breaks (SSB) which leads as a consequence to double-strand breaks (DSBs). This disorder is particularly harmful to cells with deficiency of BRCA1/2 protein which is involved in repair of DNA double-strand breaks. This phenomenon is an example of "synthetic lethality" concept and contributes to research on application of PARP inhibitors in treatment of cancers associated with BRCA1/2 protein defect (breast or ovarian cancer). Noticed synergism between PARP inhibitors and genotoxic chemotherapy or radiotherapy determined another direction of research on application of these medicaments. After promising results of phase I and II trials with most commonly investigated PARP inhibitors--iniparib and olaparib--which recruited patients with triple negative breast cancer and ovarian cancer, further studies started. This paper presents theoretical basis of PARP inhibitors action as well as critical review of most important clinical trials of these medicaments.

[Poly(ADP-ribose) polymerase (PARP) inhibitors in BRCA1/2 cancer therapy]. / Inhibitory polimerazy poli(ADP-rybozy) (PARP) w terapii nowotworów z mutacjami BRCA1/2.

 A majority of currently used anticancer drugs belong to a group of chemical agents that damage DNA. The efficiency of the treatment is limited by effective DNA repair systems functioning in cancer cells. Many chemotherapeutic compounds cause strong systemic toxicity. Therefore, there is still a need for new anticancer agents which are less toxic for nontransformed cells and selectively kill cancer cells. One of the most promising molecular targets in cancer therapy is poly(ADP-ribose) polymerases (PARP). PARP play an essential role in repairing DNA strand breaks. Small molecule inhibitors of these enzymes have been developed and have proved to be extremely toxic for cancer cells that lack the functional BRCA1 and BRCA2 proteins that are involved in homologous recombination, a complex repair mechanism of DNA double strand breaks. Mutations in BRCA1/2 genes are associated with genetically inherited breast and ovarian cancers. Therefore PARP inhibitors may prove to be very effective and selective in the treatment of these cancer types. This review is focused on the function of BRCA1/2 proteins and poly(ADP-ribose) polymerases in DNA repair systems, especially in the homologous recombination process. A short history of the studies that led to synthesis of high specificity small molecule PARP inhibitors is also presented, as well as the results of clinical trials concerning the most effective PARP inhibitors in view of their potential application in oncological treatment, particularly breast cancers.

Targeting the DNA damage response in oncology: past, present and future perspectives.

PURPOSE OF REVIEW: The success of poly(ADP-ribose) polymerase inhibition in BRCA1 or BRCA2 deficient tumors as an anticancer strategy provided proof-of-concept for a synthetic lethality approach in oncology. There is therefore now active interest in expanding this approach to include other agents targeting the DNA damage response (DDR). We review lessons learnt from the development of inhibitors against DNA damage response mechanisms and envision the future of DNA repair inhibition in oncology. RECENT FINDINGS: Preclinical synthetic lethality screens may potentially identify the best combinations of DNA-damaging drugs with inhibitors of DNA repair and the DDR or two agents acting within the DDR. Efforts are currently being made to establish robust and cost-effective assays that may be implemented within appropriate time-scales in parallel with future clinical studies. Detection of relevant mutations in a high-throughput manner, such as with next-generation sequencing for genes implicated in homologous recombination, including BRCA1, BRCA2, and ataxia telangiectasia mutated is anticipated. Novel approaches targeting the DDR are currently being evaluated and inhibitors of ATM, RAD51 and DNA-dependent protein kinase are now in early drug discovery and development. SUMMARY: There remains great enthusiasm in oncology practice for pursuing the strategy of synthetic lethality. The future development of antitumor agents targeting the DDR should include detailed correlative biomarker work within early phase clinical studies wherever possible, with clear attempts to identify doses at which robust target modulation is observed.

The unliganded glucocorticoid receptor positively regulates the tumor suppressor gene BRCA1 through GABP beta.

Loss of BRCA1 tumor suppressor function is a critical event in breast tumorigenesis. We have previously identified the stress hormone hydrocortisone as a negative regulator of BRCA1 expression in nonmalignant mammary cells. Here, we have identified a direct role for the unliganded glucocorticoid receptor (GR) in BRCA1 upregulation in the absence of hydrocortisone. The positive regulatory effect of GR is lost upon the addition of hydrocortisone. We have shown that GR interacts with the BRCA1 promoter only in the absence of hydrocortisone, and that this interaction is mediated through the ß-subunit of the ets transcription factor GA-binding protein (GABP) at the RIBS promoter element. GR and GABPß interact in both coimmunoprecipitation and mammalian two-hybrid assays, and this interaction involves the N-terminal to central regions of both proteins. This work presents the first evidence of a ligand-independent role for GR as a positive regulator of gene expression, and loss of GR from the BRCA1 promoter in response to stress hormones leads to decreased BRCA1 expression. Because low levels of BRCA1 have been implicated in the development of sporadic breast cancer, this may represent a novel mechanism through which prolonged stress signaling increases breast cancer risk.

kConFab: a familial breast cancer consortium facilitating research and translational oncology.

In 2005, 100,514 Australians were diagnosed with cancer, and over 10,000 of these cancers will be due to heritable causes. The impact of familial cancer by definition extends beyond the individual, affecting tens of thousands of parents, siblings, and children. The study of familial cancer causes has arguably made the greatest single contribution to our understanding of cancer biology. This knowledge is used clinically to guide investment in screening and prevention, as well as being translated into new treatments.

[PARP inhibitors: new therapeutic agents in breast and ovarian cancer]. / Inhibiteurs de la PARP: nouvelle arme thérapeutique pour les cancers du sein et de l'ovaire.

PARP inhibitors are novel drugs under development in oncology, particularly against breast and ovarian cancer. They act on the DNA repair mechanisms in synergy with the loss of BRCA function of the tumor cells, thereby inducing a genetic instability that leads to cell death. The clinical benefit of PARP inhibitors has been demonstrated for breast and ovarian cancer in BRCA germline mutation carriers. Their use in sporadic triple negative breast cancers, that share similarities with BRCA1 mutated tumors, is currently investigated with encouraging preliminary results.

Altered BRCA1 and BRCA2 responses and mutation of BRCA1 gene in mice exposed chronically and transgenerationally to aqueous extract of betel nut (AEBN).

The Brca1 and Brca2 tumor suppressor genes are involved in the maintenance of genomic integrity as they facilitate error free DNA repair. This study was designed to understand the role of Brca1 and Brca2 in betel nut (BN) induced chronic and transgenerational carcinogenesis in mice. Young male and female Swiss Albino mice were chronically as well as transgenerationally exposed to aqueous extract of betel nut (AEBN) in drinking water (2 mg ml(-1)) for up to 24 weeks. In chronically exposed mice, the levels of Brca1 and Brca2 proteins were elevated to approximately 1.4-fold over the age matched controls after 2 weeks of exposure to AEBN, followed by a decline below the controls. In transgenerationally exposed mice, both Brca1 and Brca2 proteins remained below the controls from the onset of AEBN exposure and rapidly declined further, indicating a loss of tumor suppressor protection. Nucleotide sequencing of exon 11 of Brca1 and exon 27 of Brca2 did not reveal mutation in liver nodules of chronically exposed mice, while a G → C mutation Brca1 was observed in liver nodules as well as in solid tumors developing in transgenerationally exposed mice. Thus, the genomic instability arising due to the lowering in the levels of Brca1 and Brca2 proteins and mutation in exon 11 of Brca1 gene contributed to the increased risk of cancer in mice exposed transgenerationally to AEBN.