Epigenomics of ovarian cancer and its chemoprevention

Prognostic Value and Therapeutic Potential of CBX Family Members in Ovarian Cancer

Background: Ovarian cancer (OV) is one of the common malignant tumors and has a poor prognosis. Chromobox (CBX) family proteins are critical components of epigenetic regulation complexes that repress target genes transcriptionally via chromatin modification. Some studies have investigated the function specifications among several CBXs members in multiple cancer types, however, little is known about the functions and prognostic roles of distinct CBXs family proteins in ovarian cancer.

Methods: In this study, several bioinformatics databases and in vitro experiments were used to analyze the expression profiles, prognostic values, and therapeutic potential of the CBXs family (CBX1-8) in ovarian cancer.

Results: It was found that higher expression of CBX3/8 and lower expression of CBX1/6/7 were detected in OV tissues. CBX2/4/5/8 were significantly correlated with individual cancer stages of OV. The expression of CBX1/2/3 were all significantly associated with worse overall survival (OS) and progression-free survival (PFS) for OV patients, whereas the expression of other five CBXs members showed either irrelevant (CBX5 and CBX8) or inconsistent (CBX4, CBX6, and CBX7) results for both OS and PFS in OV. These results showed that only CBX3 had consistent results in expression and prognosis. Further cell experiments also showed that CBX3 promoted the proliferation of ovarian cancer cells. CBX3 was highly expressed in chemoresistant OV tissues. These results indicated that CBX3 was the most likely prognostic indicator and new therapeutic target in OV. Furthermore, gene enrichment analysis suggests that the CBXs family was primarily involved in mast cell activation and mast cell mediated immunity. Individual CBXs members were associated with varying degrees of the infiltration of immune cells, especially B cells. Finally, a high genetic alteration rate of CBXs family (39%) was observed in OV. The low methylation status of CBX3/8 in OV may be associated with their high expression levels.

Conclusions: Taken together, these findings exhibited the pivotal value of CBXs family members (especially CBX3) in the prognosis and chemoresistance of ovarian cancer. Our results may provide new insight to explore new prognostic biomarkers and therapeutic targets for ovarian cancer.

Nedaplatin reduces multidrug resistance of non-small cell lung cancer by downregulating the expression of long non-coding RNA MVIH

Cisplatin-based chemotherapy is the standard treatment for non-small cell lung cancer (NSCLC). However, drug resistance emergences after treatment. Long non-coding RNA microvascular invasion in hepatic cancer (MVIH) plays an important role in drug resistance in a variety of cancers. This study investigates the role of nedaplatin on multidrug resistance in NSCLC and its relationship with MVIH. Lung cancer A549 and H1650 cells were treated with cisplatin to obtain multidrug-resistant A549/DDP and H1650/ DDP cells. A549/DDP and H1650/ DDP cells were treated with nedaplatin, MVIH siRNA and siRNA NC. It was found that both MVIH siRNA and nedaplatin significantly reduce the mRNA expression of MVIH in A549/DDP and H1650/ DDP cells. MTT assay showed that the proliferation of MDR cells was significantly higher than that of other cells. Nedaplatin and MVIH siRNA significantly inhibit the proliferation of A549 and H1650 cells. The results of colony formation assay were consistence with MTT results. Nedaplatin and MVIH siRNA significantly reduced colony formation in MDR cells. Flow cytometry showed that NDP and MVIH siRNA significantly decrease the proportion of cells in G0/G1 and increase the proportion of cells in S phase compared with untreated and MDR cells. The apoptotic rate of MDR cells was significantly lower than that of other cells, while the apoptosis rate of cells in NDP and MVIH siRNA group was significantly higher than that of the other three groups of cells. Wound healing assay and Transwell chamber experiments confirmed that both NDP and MVIH siRNA significantly reduced the migration and invasion abilities of MDR cells. The expression of E-cadherin in MDR cells was significantly lower than that in untreated cells, and the expression of N-cad, α-SMA and Vimentin significantly increased in the MDR cells. NPD and MVIH siRNA reverse the EMT process. In conclusion, LncRNA MVIH is upregulated in drug resistant NSCLC cells. Nedaplatin can reduce the expression of MVIH and reverse EMT process, thus reversing the drug resistance of cisplatin in non-small cell lung cancer cells.

Involvement of mitochondrial dynamics in the antineoplastic activity of cisplatin in murine leukemia L1210 cells

Leukemia is a type of hematopoietic stem cell malignant cloned disease with high mortality. Cisplatin-based chemotherapy is one of the most common treatments for leukemia. Similar to other chemotherapeutic agents, cisplatin resistance has become a serious issue in cancer therapy. In the present study, we investigated the role of mitochondrial dynamics in the antineoplastic activity of cisplatin in murine leukemia L1210 cells. Firstly, the L1210 cell line resistant to cisplatin (L1210/DDP) was established. Compared to its parental cell line, the IC50 value of cisplatin in the L1210/DDP cells was increased 10-fold. Mitofusins (Mfn1 and Mfn2), mitochondrial outer membrane fusion proteins, were markedly upregulated in the L1210/DDP cells, whereas the expression of fission protein Drp1 and inner membrane fusion protein OPA1 were not significantly altered. In addition, mitofusins were also upregulated in the parental L1210 cells subjected to cisplatin stress. To investigate the role of mitochondrial dynamics in the antineoplastic activity of cisplatin, the effect of mitochondrial division inhibitor (Mdivi)-1 on cisplatin‑induced cell death, caspase-3 cleavage and ROS production was examined in L1210 cells. We found that 5 µM of Mdivi-1 efficiently attenuated cisplatin-induced cell death, caspase activation and intracellular ROS increase in L1210 cells. Our data indicated that mitochondrial dynamics play an important role in the antineoplastic activity of cisplatin, and mitofusin-mediated mitochondrial fusion may be involved in the process of cisplatin resistance in leukemia cells. Therefore, the present study revealed that mitochondrial dynamics may be a potential target used to improve the antineoplastic activity of cisplatin in leukemia in the future.

Research Priorities for Endometriosis

The 3rd International Consensus Workshop on Research Priorities in Endometriosis was held in São Paulo on May 4, 2014, following the 12th World Congress on Endometriosis. The workshop was attended by 60 participants from 19 countries and was divided into 5 main sessions covering pathogenesis/pathophysiology, symptoms, diagnosis/classification/prognosis, disease/symptom management, and research policy. This research priorities consensus statement builds on earlier efforts to develop research directions for endometriosis. Of the 56 research recommendations from the 2011 meeting in Montpellier, a total of 41 remained unchanged, 13 were updated, and 2 were deemed to be completed. Fifty-three new research recommendations were made at the 2014 meeting in Sao Paulo, which in addition to the 13 updated recommendations resulted in a total of 66 new recommendations for research. The research recommendations published herein, as well as those from the 2 previous papers from international consensus workshops, are an attempt to promote high-quality research in endometriosis by identifying and agreeing on key issues that require investigation. New areas included in the 2014 recommendations include infertility, patient stratification, and research in emerging nations, in addition to an increased focus on translational research. A revised and updated set of research priorities that builds on this document will be developed at the 13th World Congress on Endometriosis to be held on May 17-20, 2017, in Vancouver, British Columbia, Canada.

The Aminosteroid Derivative RM-133 Shows In Vitro and In Vivo Antitumor Activity in Human Ovarian and Pancreatic Cancers

Ovarian and pancreatic cancers are two of the most aggressive and lethal cancers, whose management faces only limited therapeutic options. Typically, these tumors spread insidiously accompanied first with atypical symptoms, and usually shift to a drug resistance phenotype with the current pharmaceutical armamentarium. Thus, the development of new drugs acting via a different mechanism of action represents a clear priority. Herein, we are reporting for the first time that the aminosteroid derivative RM-133, developed in our laboratory, displays promising activity on two models of aggressive cancers, namely ovarian (OVCAR-3) and pancreatic (PANC-1) cancers. The IC₅₀ value of RM-133 was 0.8 μM and 0.3 μM for OVCAR-3 and PANC-1 cell lines in culture, respectively. Based on pharmacokinetic studies on RM-133 using 11 different vehicles, we selected two main vehicles: aqueous 0.4% methylcellulose:ethanol (92:8) and sunflower oil:ethanol (92:8) for in vivo studies. Using subcutaneous injection of RM-133 with the methylcellulose-based vehicle, growth of PANC-1 tumors xenografted to nude mice was inhibited by 63%. Quite interestingly, RM-133 injected subcutaneously with the methylcellulose-based or sunflower-based vehicles reduced OVCAR-3 xenograft growth by 122% and 100%, respectively. After the end of RM-133 treatment using the methylcellulose-based vehicle, OVCAR-3 tumor growth inhibition was maintained for ≥ 1 week. RM-133 was also well tolerated in the whole animal, no apparent sign of toxicity having been detected in the xenograft studies.

Risk assessment for epithelial ovarian cancer: proposing a new approach to a deadly problem

Presently the majority of women diagnosed with epithelial ovarian cancer (EOC) have advanced stage disease (III-IV) with a poor 5-year survival rate (12-30 %). This significantly contrasts when early stage disease is detected, which has a 5-year survival rate approximating 90 %. Therefore, detection of early stage disease is critical to making an impact on outcome. By using genetic algorithms, modifications of transvaginal ultrasonography and use of novel biomarkers, we propose a risk assessment profile to identify at-risk women and enable ovarian cancer screening to become a reality. Such a novel algorithm starts by applying classic genetic pedigree assessment and uses a panel of multiple biomarkers that identify both phenotypic and genotypic expression of high-risk markers followed with conventional ultrasound and advanced ultrasound techniques such as microvascular contrast-enhancement as a secondary test. We presently employ a multidisciplinary program incorporating genetics, molecular biology, tumor immunology, gynecologic oncology and diagnostic imaging to identify asymptomatic high risk women.

Mitochondrial dynamics regulates hypoxia-induced migration and antineoplastic activity of cisplatin in breast cancer cells

Mitochondria are high dynamic organelles with frequent fission and fusion. Here, we found hypoxia stimulated Drp1 expression, mitochondrial fission and migration in metastatic MDA-MB‑231 cells, but not in non-metastatic MCF-7 cells. Inhibition of Drp1-dependent mitochondrial fission by Mdivi-1 or silencing Drp1 attenuated hypoxia-induced mitochondrial fission and migration in MDA-MB‑231 cells. On the other hand, cisplatin induced significant apoptosis and mitochondrial fission in MDA-MB‑231 cells, but not in MCF-7 cells. Mdivi-1 and silencing Drp1 also efficiently prevented cisplatin-induced MMP decrease, ROS production and apoptosis in MDA-MB‑231 cells. Our data suggest that Drp1-dependent mitochondrial fission not only regulates hypoxia-induced migration of breast cancer cells, but also facilitates its sensitivity to chemotherapeutic agents. Thus, targeting Drp1-dependent mitochondrial dynamics may provide a novel strategy to suppress breast cancer metastasis and improve the chemotherapeutic effect in the future.

DNA methylation profiles in ovarian cancer: implication in diagnosis and therapy (Review)

Genetic alterations alone cannot account for the complexity of ovarian cancer. The potential reversibility of epigenetic mechanisms makes them attractive candidates for the prevention and/or treatment of ovarian carcinoma. Detection of the epigenetic signature of each cancer cell may be useful in the identification of candidate biomarkers for disease detection, classification and monitoring and may also facilitate personalized cancer treatment. In ovarian cancer, in addition to other non-gynaecological cancers, two opposite epigenetic phenomena occur. The first involves an overall global decrease in DNA methylation of heterochromatin leading to demethylation of several oncogenes, while the second involves specific CpG island hypermethylation associated with the promoters of tumor suppressor genes. Early studies focused on the methylation patterns of single genes associated with tumorigenesis. However, newer genome-wide methods have identified a group of genes whose regulation is altered by DNA methylation during ovarian cancer progression.

Pathway modulations and epigenetic alterations in ovarian tumorbiogenesis

Cellular pathways are numerous and are highly integrated in function in the control of cellular systems. They collectively regulate cell division, proliferation, survival and apoptosis of cells and mutagenesis of key genes that control these pathways can initiate neoplastic transformations. Understanding these pathways is crucial to future therapeutic and preventive strategies of the disease. Ovarian cancers are of three major types; epithelial, germ-cell, and stromal. However, ovarian cancers of epithelial origin, arising from the mesothelium, are the predominant form. Of the subtypes of ovarian cancer, the high-grade serous tumors are fatal, with low survival rate due to late detection and poor response to treatments. Close examination of preserved ovarian tissues and in vitro studies have provided insights into the mechanistic changes occurring in cells mediated by a few key genes. This review will focus on pathways and key genes of the pathways that are mutated or have aberrant functions in the pathology of ovarian cancer. Non-genetic mechanisms that are gaining prominence in the pathology of ovarian cancer, miRNAs and epigenetics, will also be discussed in the review.

Epigenetic silencing of the LDOC1 tumor suppressor gene in ovarian cancer cells

PURPOSE

Due to very unspecific symptoms ovarian cancer often is diagnosed only at a late stage of the disease. Thus, morbidity and mortality of the patients are high. Even the established tumor marker CA12-5 shows only low specificity, rising the need for alternative biomarkers capable of detecting early stages of ovarian cancer. We analyzed the expression of the tumor suppressor candidate gene LDOC1 (leucine zipper downregulated in cancer 1) as a potential early biomarker in ovarian cancer cell lines.

METHODS

A total of seven ovarian cancer cell lines were analyzed by RT-PCR (reverse transcriptase polymerase chain reaction) and real-time PCR for expression of LDOC1. Verification of promoter methylation was performed using methylation-specific primers on bisulfite-modified genomic DNA.

RESULTS

Three out of seven ovarian cancer cell lines showed a complete loss of LDOC1 gene expression. LDOC1 silencing was caused neither by gene deletion nor gene rearrangements, but by methylation and subsequent inactivation of the concerned promoter as proofed by methylation specific primers. Similarly, promoter methylation could be inhibited by adding AdC (5-aza-2'-deoxycytidine), an inhibitor of DNA methyltransferases. As a result, a reactivation of the LDOC1 gene was seen.

CONCLUSIONS

The tumor suppressor gene LDOC1 in ovarian cancer cell lines is downregulated by promoter methylation and thus may serve as an early biomarker. Further investigation will show if detection of methylated LDOC1 in peripheral blood has both adequate sensitivity and specificity for a timely non-invasive detection of ovarian cancer.

Antitumor Activities of Rauwolfia vomitoria Extract and Potentiation of Carboplatin Effects Against Ovarian Cancer

Background

Tumor resistance to platinum-based drugs has been an obstacle to the treatment of ovarian cancer. Extract of the plant Rauwolfia vomitoria has long been used by cancer patients. However, there have not been systematic studies of its anticancer activity.

Objective

In an effort to enhance the effectiveness of platinum-based drugs, we investigated the anticancer effect of a Rauwolfia vomitoria extract (Rau), both alone and in combination with carboplatin (Cp).

Methods

In vitro cytotoxicity and colony formation were evaluated in several ovarian cancer cell lines. In vivo effects were evaluated in an intraperitoneal ovarian cancer mouse model. The combination of Rau and Cp was assessed using Chou-Talalay’s constant ratio design and median effect analysis based on the isobologram principle to determine the combination index values.

Results

Rau decreased cell growth in all 3 tested ovarian cancer cell lines dose dependently and completely inhibited formation of colonies in soft agar. Apoptosis was induced in a time- and dose-dependent manner and was the predominant form of Rau-induced cell death. Synergy of Rau with Cp was detected, with combination index values <1 and dose reduction index values for Cp ranging from 1.7- to 7-fold. Tumor growth in mice was significantly suppressed by 36% or 66% with Rau treatment alone at a low (20 mg/kg) or a high dose (50 mg/kg), respectively, an effect comparable to that of Cp alone. The volume of ascitic fluid and the number of nonblood cells in ascites were also significantly decreased. Combining Rau with Cp remarkably enhanced the effect of Cp and reduced tumor burden by 87% to 90% and ascites volume by 89% to 97%.

Conclusions

Rau has potent antitumor activity and in combination significantly enhances the effect of Cp against ovarian cancer.

The plant extract of Pao pereira potentiates carboplatin effects against ovarian cancer

CONTEXT

Herbal preparation of Pao pereira [Geissospermum vellosii Allem (Apocynaceae)] has long been used by oncologic patients and Integrative Medicine practitioners in South America. However, its anticancer activities have not been systematically studied.

OBJECTIVE

To investigate the anticancer effects of β-carboline alkaloids-enriched extract from Pao pereira (Pao), either alone or in combination with carboplatin, in preclinical ovarian cancer models.

MATERIALS AND METHODS

Cytotoxicity of Pao (0-800 µg/ml) against different ovarian cancer cell lines and an immortalized epithelial cell line was detected by flow cytometry, MTT assay and colony formation in soft agar. Combination of Pao and carboplatin, a primary chemotherapeutic drug for ovarian cancer, was evaluated using Chou-Talalay's methods. Mice bearing intraperitoneally spread ovarian cancer were treated with 20 or 50 mg/kg/day Pao by i.p. injection. Carboplatin at 15 mg/kg/week i.p. was compared and combined to Pao treatments.

RESULTS

Pao selectively inhibited ovarian cancer cell growth with IC₅₀ values of 180-235 µg/ml, compared to 537 µg/ml in normal cells. Pao induced apoptosis dose- and time-dependently and completely inhibited colony formation of tumor cells in soft agar at 400 µg/ml. Pao greatly enhanced carboplatin cytotoxicity, with dose reduction (DRIs) for carboplatin at 1.2-10 fold. In vivo, Pao alone suppressed tumor growth by 79% and decreased volume of ascites by 55%. When Pao was combined with carboplatin, tumor inhibition reached 97% and ascites was completely eradicated.

DISCUSSION AND CONCLUSION

Pao possess potent antitumor activity and could enhance carboplatin effect, and therefore holds therapeutic potential in the treatment of ovarian cancer.

Ovarian cancer stem cells: are they real and why are they important?

The cancer stem cell hypothesis has been put forward as a paradigm to describe varying levels of aggressiveness in heterogeneous tumors. Specifically, many subpopulations have been clearly demonstrated to possess increased tumorigenicity in mice, broad differentiating capacity, and resistance to therapy. However, the extent to which these experimental findings are potentially clinically significant is still not clear. This review will describe the principles of this emerging hypothesis, ways in which it may be appropriate in ovarian cancer based on the clinical course of the disease, and how we might exploit it to improve outcomes in ovarian cancer patients.

Endometriosis is characterized by a distinct pattern of histone 3 and histone 4 lysine modifications

BACKGROUND

The histone modification patterns in endometriosis have not been fully characterized. This gap in knowledge results in a poor understanding of the epigenetic mechanisms (and potential therapeutic targets) at play. We aimed to (1) assess global acetylation status of histone 3 (H3) and histone 4 (H4), (2) measure levels of H3 and H4 lysine (K) acetylation and methylation, and (3) to identify histone acetylation patterns in promoter regions of candidate genes in tissues from patients and controls.

METHODS

Global and K-specific acetylation/methylation levels of histones were measured in 24 lesions, 15 endometrium from patients, and 26 endometrium from controls. Chromatin immunoprecipitation (ChIP)-polymerase chain reaction was used to determine the histone acetylation status of the promoter regions of candidate genes in tissues.

RESULTS

The lesions were globally hypoacetylated at H3 (but not H4) compared to eutopic endometrium from controls. Lesions had significantly lower levels of H3K9ac and H4K16ac compared to eutopic endometrium from patients and controls. Tissues from patients were hypermethylated at H3K4, H3K9, and H3K27 compared to endometrium from controls. The ChIP analysis showed hypoacetylation of H3/H4 within promoter regions of candidate genes known to be downregulated in endometriosis (e.g., HOXA10, ESR1, CDH1, and p21 (WAF1/Cip1) ) in lesions versus control endometrium. The stereoidogenic factor 1 (SF1) promoter region was enriched for acetylated H3 and H4 in lesions versus control tissues, correlating with its reported high expression in lesions.

CONCLUSIONS

This study describes the histone code of lesions and endometrium from patients with endometriosis and provides support for a possible role of histone modification in modulation of gene expression in endometriosis.

Biomarkers for early detection of ovarian cancer

Ovarian cancer is the most lethal gynecological malignancy. However, effective screening strategies have not been established and continue to be elusive. A good screening test must adequately address validity, reliability, yield, cost, acceptance and follow-up services. An ideal screening test for ovarian cancer must have a high sensitivity in order to correctly diagnose all women with the disease and a high specificity to avoid false-positive results. The current screening modalities of bimanual examination, CA-125 and transvaginal ultrasonography together allow us to detect only 30-45% of women with early-stage disease. Recent developments in proteomic and genomic research have identified a number of potential biomarkers. Although panels of tumor markers and proteomic-based technologies may improve the positive predictive value, all markers require validation and interfacing with newly developed diagnostic imaging technologies. While a large amount of information on miRNAs has been promising, much remains to be elucidated. This review will examine the current status of biomarkers and technologies of interest in the effort of early detection of ovarian cancer.

Inhibition of DNA methyltransferases, histone deacetylases and lysine-specific demethylase-1 suppresses the tumorigenicity of the ovarian cancer ascites cell line SKOV3

Ovarian cancer is one of the most lethal female malignancies and epigenetic abnormalities are thought to play a vital role in the pathogenesis, development and progression of ovarian cancer. Our goal was to investigate whether the combination of trichostatin A (TSA) and 5-aza-2'-deoxycytidine (decitabine) was superior to single agent on tumorigenicity of ovarian cancer cells. We found that tumorigenicity and metastasis of SKOV3 cells were significantly suppressed by the combination of TSA and decitabine in xenograft mouse models. Migration capacity was markedly suppressed through the induction of E-cadherin and suppression of N-cadherin when treated with TSA and decitabine. Invasion was also suppressed at least partially through inhibition of MMP-2 and MMP-9 with the combined treatment. The combination drugs markedly inhibited spheroid formation and significantly impaired migration and invasion capacity of spheroid derived cells through inhibition of Twist, N-cadherin, MMP-2, MMP-9 and induction of E-cadherin. Epigenetically, the activity of DNA methyltransferases (DNMTs) and histone deacetylases (HDACs) were markedly inhibited when TSA was used in combination with decitabine, especially the expression of DNMT3A/3B and HDAC1/2. Acetylation of histone H3 and H4 were more markedly stimulated with the combination than with either agent alone. The expression level of lysine-specific demethylase-1 (LSD1) was also suppressed. The transcription activity marker dimethylated-H3K4 was induced, but the dimethylated-H3K9 was suppressed by exposure to the combined drugs. These results suggest that the combination of TSA and decitabine significantly suppresses tumorigenicity by inhibiting migration and invasion of ovarian cancer cells via regulating the expression of the cadherins and MMPs, which may be epigenetically regulated by DNA methylation and histone modification.

Tumor suppressor genes associated with drug resistance in ovarian cancer (review)

Ovarian cancer is a fatal gynecological cancer and a major cause of cancer-related mortality worldwide. The main limitation to a successful treatment for ovarian cancer is the development of drug resistance to combined chemotherapy. Tumor suppressor genes (TSGs) are wild-type alleles of genes which play regulatory roles in diverse cellular activities, and whose loss of function contributes to the development of cancer. It has been demonstrated that TSGs contribute to drug resistance in several types of solid tumors. However, an overview of the contribution of TSGs to drug resistance in ovarian cancer has not previously been reported. In this study, 15 TSGs responding to drug resistance in ovarian cancer were reviewed to determine the relationship of TSGs with ovarian cancer drug resistance. Furthermore, gene/protein-interaction and bio-association analysis were performed to demonstrate the associations of these TSGs and to mine the potential drug resistance-related genes in ovarian cancer. We observed that the 15 TSGs had close interactions with each other, suggesting that they may contribute to drug resistance in ovarian cancer as a group. Five pathways/processes consisting of DNA damage, apoptosis, cell cycle, DNA binding and methylation may be the key ways with which TSGs participate in the regulation of drug resistance. In addition, ubiquitin C (UBC) and six additional TSGs including the adenomatous polyposis coli gene (APC), death associated protein kinase gene (DAPK), pleiomorphic adenoma gene-like 1 (PLAGL1), retinoblastoma susceptibility gene (RB1), a gene encoding an apoptosis-associated speck-like protein (PYCARD/ASC) and tumor protein 63 (TP63), which had close interactions with the 15 TSGs, are potential drug resistance-related genes in ovarian cancer.

Enhancement of Cisplatin-Mediated Apoptosis in Ovarian Cancer Cells through Potentiating G2/M Arrest and p21 Upregulation by Combinatorial Epigallocatechin Gallate and Sulforaphane

Advanced-stage ovarian cancer is characterized by high mortality due to development of resistance to conventional chemotherapy. Novel compounds that can enhance the efficacy of conventional chemotherapy in ovarian cancer may overcome this drug resistance. Consumption of green tea (epigallocatechin gallate, EGCG) and cruciferous vegetables (sulforaphane, SFN) is inversely associated with occurrence of ovarian cancer and has anticancer effects through targeting multiple molecules in cancer cells. However, the effects of EGCG and SFN combinational treatment on ovarian cancer cells and on efficacy of cisplatin to these cells are unknown. In this study, EGCG or SFN was used to treat both cisplatin-sensitive (A2780) and cisplatin-resistant (A2780/CP20) ovarian cancer cells alone or in combination with cisplatin. We found that EGCG and SFN combinational treatment can reduce cell viability of both ovarian cancer cell lines time- and dose-dependently. Furthermore, EGCG and SFN combinational treatment can enhance cisplatin-induced apoptosis and G2/M phase arrest, thereby enhancing the efficacy of cisplatin on both cisplatin-sensitive and cisplatin-resistant ovarian cancer cells. EGCG and SFN combinational treatment upregulated p21 expression induced by cisplatin in cisplatin-sensitive ovarian cancer cells, while p27 expression was not regulated by these treatments. Collectively, these studies provide novel approaches to overcoming cisplatin chemotherapy resistance in ovarian cancer.

Knockdown of survivin contributes to antitumor activity in cisplatin-resistant ovarian cancer cells

Survivin (SVV) is an important member of the inhibitor of apoptosis family. It is overexpressed in a number of cancer types, including human ovarian carcinomas. SVV promotes invasion, metastasis, growth and survival of malignant cells and confers resistance to specific chemotherapeutic drugs. The present study aimed to elucidate the role and possible mechanisms of SVV in cisplatin-resistant ovarian cancer cells (A2780/CP). Using a loss-of-function approach, we investigated the effects of adenovirus-mediated knockdown of SVV by small hairpin RNA (ad5-SVV) on the expression of pro-caspase-3, cleaved caspase-3, proliferating cell nuclear antigen (PCNA) and matrix metalloproteinase-2 (MMP-2) in A2780/CP cells by real-time PCR and western blot analysis. Proliferation was measured by MTT assay, invasive potential by Transwell, and cell apoptosis by FITC-Annexin V and propidium iodide for the functional analysis of A2780/CP cells following infection with ad5-SVV. As a result, knockdown of SVV downregulated the expression of PCNA and MMP-2 and upregulated the expression of pro-caspase-3 and cleaved caspase-3. In addition, knockdown of SVV enhanced cisplatin-induced proliferative activities, induced cell apoptosis and inhibited the invasive potential in A2780/CP cells. The present findings demonstrate that knockdown of SVV contributes to antitumor activity in cisplatin-resistant ovarian cancer cells via the downregulation of PCNA and MMP-2 expression and the upregulation of caspase-3 expression and indicate that SVV is a potential target for therapeutic anticancer drugs.

Cell senescence culturing methods

Development of therapeutic approaches that slow or ablate the adverse physiological and pathological changes associated with aging has been considered as an important goal for gerontological research. As cellular senescence is characterized as the basis for aging in organisms, culturing and subculturing of normal human diploid fibroblasts to mimic the in vivo aging processes have been developed as major methods to investigate molecular events involved in aging. It has been established that normal human diploid fibroblasts can proliferate in culture for only finite periods of time. There are many ways to study aging in vitro. In this chapter, we will discuss some of the basic laboratory procedures for cell senescence culturing methods.

Investigation of the expression patterns and correlation of DNA methyltransferases and class I histone deacetylases in ovarian cancer tissues

Recent studies have reported that DNA methyltransferases (DNMTs) and histone deacetylases (HDACs) are involved in the epigenetic regulation of cancer, as well as promoting cell proliferation and tumorigenesis. These mechanisms also play important roles in ovarian cancer, but little is known concerning the correlation of DNMTs and HDACs in ovarian cancer. In the present study, we used quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) and immunohistochemical staining to examine the mRNA and protein expression of DNMTs and class I HDACs of tissues from 22 cases of ovarian cancer and 8 normal ovaries as a control. Furthermore, we assessed the correlation with clinicopathological stages and the mRNA expression of these genes. The results indicated that the mRNA expression of DNMT1, DNMT3b and class I HDACs was increased in ovarian cancers, while the expression of DNMT3a was not different between cancer tissues and normal ovaries. Additionally, the results of immunohistochemical staining demonstrated that DNMT1 and DNMT3b were significantly increased in ovarian cancer samples. Furthermore, the expression of DNMT1, DNMT3b, HDAC1 and HDAC2 was significantly higher in stage III/IV compared with stage I/II ovarian carcinomas. The expression of HDAC2 was positively correlated with HDCA1, HDAC3 and HDAC8, and DNMT1 was positively correlated with DNMT3b. Simultaneously, DNMT3b was correlated with HDAC1 and HDAC2. HDAC1 may upregulate the expression of DNMTs, but this requires confirmation by in vitro and in vivo experiments. The overall high rate of expression for class I HDACs, DNMT1 and DNMT3b suggested that these mRNAs should be explored as predictive factors in ovarian cancer. In addition, HDAC1, HDAC2 and DNMT3b cooperated in controlling ovarian cancer progression. Determining the correlations between HDACs and DNMTs in ovarian cancer will not only further clarify the mechanisms of genesis and development, but also guide clinical therapy using the inhibitors of HDACs and DNMTs.

NotI microarrays: novel epigenetic markers for early detection and prognosis of high grade serous ovarian cancer

Chromosome 3-specific NotI microarray (NMA) containing 180 clones with 188 genes was used in the study to analyze 18 high grade serous ovarian cancer (HGSOC) samples and 7 benign ovarian tumors. We aimed to find novel methylation-dependent biomarkers for early detection and prognosis of HGSOC. Thirty five NotI markers showed frequency of methylation/deletion more or equal to 17%. To check the results of NMA hybridizations several samples for four genes (LRRC3B, THRB, ITGA9 and RBSP3 (CTDSPL)) were bisulfite sequenced and confirmed the results of NMA hybridization. A set of eight biomarkers: NKIRAS1/RPL15, THRB, RBPS3 (CTDSPL), IQSEC1, NBEAL2, ZIC4, LOC285205 and FOXP1, was identified as the most prominent set capable to detect both early and late stages of ovarian cancer. Sensitivity of this set is equal to (72 ± 11)% and specificity (94 ± 5)%. Early stages represented the most complicated cases for detection. To distinguish between Stages I + II and Stages III + IV of ovarian cancer the most perspective set of biomarkers would include LOC285205, CGGBP1, EPHB1 and NKIRAS1/RPL15. The sensitivity of the set is equal to (80 ± 13)% and the specificity is (88 ± 12)%. Using this technique we plan to validate this panel with new epithelial ovarian cancer samples and add markers from other chromosomes.

Involvement of autophagy in ovarian cancer: a working hypothesis

Autophagy is a lysosomal-driven catabolic process that contributes to preserve cell and tissue homeostases through the regular elimination of damaged, aged and redundant self-constituents. In normal cells, autophagy protects from DNA mutation and carcinogenesis by preventive elimination of pro-oxidative mitochondria and protein aggregates. Mutations in oncogenes and oncosuppressor genes dysregulate autophagy. Up-regulated autophagy may confer chemo- and radio-resistance to cancer cells, and also a pro-survival advantage in cancer cells experiencing oxygen and nutrient shortage. This fact is the rationale for using autophagy inhibitors along with anti-neoplastic therapies. Yet, aberrant hyper-induction of autophagy can lead to cell death, and this phenomenon could also be exploited for cancer therapy. The actual level of autophagy in the cancer cell is greatly affected by vascularization, inflammation, and stromal cell infiltration. In addition, small non-coding microRNAs have recently emerged as important epigenetic modulators of autophagy. The present review focuses on the potential involvement of macroautophagy, and on its genetic and epigenetic regulation, in ovarian cancer pathogenesis and progression.