Chemoresistant Ovarian Cancer Cells Research Articles

The Effect of Olaparib and Bortezomib Combination Treatment on Ovarian Cancer Cell Lines

Objective: Ovarian cancer (OC) is the deadliest gynecologic malignancy and has a poor survival rate due to late diagnosis and chemoresistance development. In the standard treatment of OC, platinum-based chemotherapeutics are used. However, following several rounds of chemotherapy, these drugs’ efficacy eventually becomes limited due to the development of chemoresistance in most patients who previously responded to this treatment. Therefore, overcoming chemoresistance in the treatment of OC is of high importance. In this study, we investigated the effect of combinatorial inhibition of poly(ADPribose) polymerase (PARP) and proteasome by olaparib and bortezomib on chemosensitive and chemoresistant OC cell lines. Materials and Methods: We used sulphorhodamine B assay to screen cell viability following drug treatments alone or in combination, and used the cytotoxicity data to model the effect of drugs on cell death in R programming environment. In addition to olaparib and bortezomib, we performed cytotoxicity screenings where we applied cisplatin to OC cells. We also carried out flow cytometry analysis to quantify apoptotic cells following treatments. Results: We showed that combination treatment was more effective on chemosensitive OC cell lines when cisplatin was not used. In the presence of cisplatin, olaparib and bortezomib combination treatment resulted in higher cytotoxicity in chemoresistant OC lines compared to chemosensitive OC cell lines. Combinatorial inhibition of PARP and proteasome led to a higher number of apoptotic cells in OV2008 chemosensitive cell line compared to drugs alone. Conclusion: Our data shows that olaparib and bortezomib combination treatment might show promise in vivo in the treatment of OC. Also, the efficacy of this combination treatment might be dependent on OC cells’ chemosensitivity profiles.

Anti-proliferative and anti-apoptotic effects of grape seed extract on chemo-resistant OVCAR-3 ovarian cancer cells.

Background and purpose:Ovarian cancer is the deadliest cancer in women. The main challenge in the inhibition of ovarian cancer cells is chemo-resistance. Seeking to overcome this issue, several strategies have been suggested, including the administration of natural products. Grape seed extract (GSE) is a good source of polyphenols and its anticancer effects have been reported by many studies. In this study we aimed to evaluate the effects of GSE on OVCAR-3, a chemo-resistant ovarian cancer line.Experimental approach:OVCAR-3 cells were treated with GSE (71 μg/mL) for 24 and 48 h. Cell viability and cell apoptosis were measured by MTT and flow cytometry. The real-time polymerase chain reaction was used to determine the expression of genes involved in the cell cycle (PTEN, DACT1, AKT, MTOR, GSK3B, C-MYC, CCND1, and CDK4) and apoptosis (BAX, BCl2, CASP3, 8 and 9). The expression of CASP3 protein was evaluated by the CASP3 assay.Findings / Results:The results showed that treatment of OVCAR-3 cells with GSE, increased the expression level of PTEN and DACT1 tumor suppressor genes, as well as apoptotic genes, CASP3, 8, and 9 (P < 0.001). Also, the induction of tumor suppressor genes expression was associated with an increase in the expression of BAX/BCL2 gene ratio as pro- and anti-apoptotic genes. The expression of the genes involved in the cell cycle, CCND1 and CDK4, was inhibited (P < 0.001). The results indicated that GSE induced cell apoptosis in a time-dependent manner (P < 0.001). Also, the GSE treatment resulted in the CASP3 protein expression (P < 0.001).Conclusion and implications:According to the results of this study, GSE may exert anti-tumorigenic effects on chemo-resistant OVCAR-3 ovarian cancer cells which might be mediated by the expression of tumor suppressor genes that interact with cell signaling pathways, cell cycle, and cell apoptosis. Hence, the consumption of GSE extract during chemotherapy may overcome part of chemo-resistance in ovarian cancer.

SNHG5 enhances Paclitaxel sensitivity of ovarian cancer cells through sponging miR-23a

BackgroundOvarian cancer is one of the most lethal gynecological malignancies throughout the world. Long non-coding RNA (lncRNA) small nucleolar RNA host gene 5 (SNHG5) has been reported to play an important role in several human cancers, but the role of SNHG5 in the chemoresistance of ovarian cancer cells is yet elusive. MethodThe expression of SNHG5 and miR-23a were determined by quantitative reverse transcriptase polymerase chain reaction. The effects of SNHG5 and miR-23a on the sensitivity of ovarian cancer cells to paclitaxel (PTX) were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and flow cytometry. The subcellular location of SNHG5 was detected by a subcellular fraction assay. The interaction between SNHG5 and miR-23a was determined by luciferase reporter assay and RNA immunoprecipitation assay. ResultsThe expression of SNHG5 was downregulated in the cancer genome atlas cohort. Similarly, decreased expression of SNHG5 was observed in ovarian cancer tissues. Moreover, lower expression of SNHG5 was found in PTX-resistant ovarian cancer patients as well as PTX-resistant ovarian cancer cell lines. Downregulation of SNHG5 expression was indicative of poor prognosis in patients with ovarian cancer. Overexpression of SNHG5 enhanced the sensitivity of SKOV3/PTX and HeyA-8/PTX cells to PTX in vitro and enhanced PTX sensitivity in tumors in vivo. Interestingly, an inverse correlation between SNHG5 and miR-23a expression was found in ovarian cancer tissues and SNHG5 functioned as a decoy for miR-23a. Silencing of miR-23a overcame the resistance of SKOV3/PTX and HeyA-8/PTX cells to PTX. More importantly, miR-23a overexpression could reverse the inductive effect of SNHG5 overexpression on PTX sensitivity of ovarian cancer cells. ConclusionSNHG5 enhanced the sensitivity of ovarian cancer cells to PTX through sponging miR-23a, providing a new mechanism of chemoresistance in ovarian cancer.

MiR-21 modulates the polarization of macrophages and increases the effects of M2 macrophages on promoting the chemoresistance of ovarian cancer

AimsChemoresistance is a major underlying cause of relapse or death in ovarian cancer patients. Emerging evidence has shown that macrophages could play an essential role in mediating the chemoresistance of cancer cells. MiR-21 has been reported to be an oncogene, which promotes chemoresistance in cancer. Here, we aim to investigate the role that miR-21 plays in polarization of macrophages and ovarian cancer progression. Main methodsThe CIBERSORT algorithm was used to investigate immune cell infiltration in ovarian cancer tissues. To explore the role that miR-21 played in macrophages, M2 macrophages transfected with a miR-21 mimic or a miR-21 inhibitor were co-cultured with ovarian cancer cells. Western blotting was used to detect protein expression levels. CCK8 was used to detect the IC50 of ovarian cancer cells. Flow cytometry was used to detect apoptosis and the cell cycle of ovarian cancer cells. Key findingsIn this study, we found that higher expression of M1 macrophages and lower expression of M2 macrophages correlated with a better prognosis of ovarian cancer patients. M2 macrophages promoted the chemoresistance of ovarian cancer cells. The results showed that miR-21 could partially regulate the polarization of macrophages. Furthermore, M2 macrophages transfected with the miR-21 mimic significantly promoted chemoresistance and inhibited apoptosis of ovarian cancer cells, while the M2 macrophages transfected with the miR-21 inhibitor showed the opposite effects. SignificancemiR-21 plays an important role in regulating macrophage polarization, therefore increasing the M2 macrophage-mediated chemoresistance in ovarian cancer cells.

Determination of chemoresistance of ovarian cancer cells in vitro

Objectives: to provide a rationale for existing approaches for the evaluation of chemoresistance of ovarian cancer in vitro, to perform a comparative analysis of the methods and to assess the perspectives of their further application.Materials and methods. For the review preparation, we analyzed articles on experimental testing of ovarian cancer resistance to chemotherapeutic agents, available at biomedical literature databases SciVerse Scopus (158), PubMed (323), Web of Science (285), RSCI (64). The review cited 37 recent publications, 12 of them being published over the past three years, and 16 articles being referred as pioneer publications on techniques previously and used today.Results. Peculiarities of the main methods for assessing the resistance and sensitivity of a cancer to various chemotherapeutic drugs using primary cultures of tumor cells obtained from biopsy or surgical material are analyzed. Proliferative and metabolic activities as well as the level of cell death were considered as the main evaluated characteristics of tumor cells. The methodological features of the described methods are discussed, as well as the prospects for their further application.Conclusion. Predictive detection of chemoresistance of ovarian cancer is based on testing the viability of tumor cells in the presence of a chemotherapeutic drug. The results of studies of the key mechanisms of chemoresistance development in tumor cells provide the rationale for improving in vitro testing.

Gene/paclitaxel co-delivering nanocarriers prepared by framework-induced self-assembly for the inhibition of highly drug-resistant tumors

While drug resistance has been recognized as the main cause of unsuccessful chemotherapy, the efficient inhibition of highly drug-resistant tumors still remains a significant challenge, especially for in vivo treatments. Drug resistance has been associated with the high expression of the multi-drug resistance gene 1 (MDR1), which can encode an efflux transporter known as P-glycoprotein (P-gp) that is located in the cellular membrane. Therefore, the combined delivery of MDR1-inhibited genes and chemotherapeutic drugs is anticipated to enable the effective inhibition of drug-resistant tumors. Herein, highly paclitaxel (PTX)-resistant ovarian (OV) cancer with a drug resistance index reaching up to ~ 60 was chosen to evaluate the performance of an efficient gene/drug co-delivery nanocarrier. Inspired by the self-assembly that occurs in cells and exosomes, we designed a biomimetic lipid/dextran hybrid nanocarrier with a diameter of ~ 100 nm to enhance the endocytosis and the efficiency of drug/gene release within the cells. This nanocarrier was fabricated via the frame-guided self-assembly of lipid amphiphiles on the surfaces of redox-cleavable dextran-based nanogels. The anionic MDR1-siRNA and the hydrophobic drug PTX were respectively loaded into the cationic lipid shell and the hydrophobic internal core of the hybrid nanocarriers. MDR1-siRNA can knock down MDR1, promoting the accumulation of PTX in cells, and thus is expected to achieve an efficient inhibitory effect against highly PTX-resistant cancer cells. Both in vitro and in vivo studies revealed that this dual-delivery system significantly enhanced the therapeutic effect in comparison with that provided by a PTX-only system. Thus, the construction of gene/chemo co-delivered lipid/dextran nanocarriers provides a new strategy to inhibit highly drug-resistant tumors both in vitro and in vivo. In addition, this work will contribute toward the development of urgently needed tumor nanotherapy that is able to overcome drug resistance while also offering an unmatched range of effective therapeutic nanocarriers. Statement of significanceThe biomimetic lipid/dextran hybrid nanocarrier with a diameter of ~ 100 nm, which was fabricated via the frame-guided self-assembly of lipid amphiphiles onto the surface of redox-cleavable dextran-based nanogels, provides a model carrier to co-deliver MDR1-siRNA and PTX. The MDR1-siRNA/PTX co-loaded biomimetic lipid/dextran hybrid nanocarriers demonstrate good capability in overcoming the PTX-resistance in highly chemo-resistant human ovarian (OV) cancer cells both in vitro and in vivo.

Ovarian Primary and Metastatic Tumors Suppressed by Survivin Knockout or a Novel Survivin Inhibitor.

Survivin, a member of the inhibitor of apoptosis family, is upregulated in multiple cancers including ovarian cancer, but is rarely detectable in normal tissues. We previously reported that survivin promoted epithelial-to-mesenchymal transition (EMT) in ovarian cancer cells, suggesting that survivin may contribute to ovarian tumor metastasis and chemoresistance. In this study, we tested whether knockout or pharmacologic inhibition of survivin overcomes chemoresistance and suppresses tumor metastasis. The genetic loss of survivin suppressed tumor metastasis in an orthotopic ovarian cancer mouse model. To pharmacologically test the role of survivin on ovarian tumor metastasis, we treated chemo-resistant ovarian cancer cells with a selective survivin inhibitor, MX106, and found that MX106 effectively overcame chemoresistance in vitro MX106 inhibited cell migration and invasion by attenuating the TGFβ pathway and inhibiting EMT in ovarian cancer cells. To evaluate the efficacy of MX106 in inhibiting ovarian tumor metastasis, we treated an orthotopic ovarian cancer mouse model with MX106, and found that MX106 efficiently inhibited primary tumor growth in ovaries and metastasis in multiple peritoneal organs as compared with vehicle-treated control mice. Our data demonstrate that inhibition of survivin using either genetic knockout or a novel inhibitor MX106 suppresses primary ovarian tumor growth and metastasis, supporting that targeting survivin could be an effective therapeutic approach in ovarian cancer.

MiR-34a-5p/PD-L1 axis regulates cisplatin chemoresistance of ovarian cancer cells.

Ovarian cancer is the most lethal gynecologic malignancy in women with an increasing number of cases worldwide. Chemoresistance is the main obstacle for ovarian cancer treatment during clinical therapy. Previous studies found that programmed cell death 1 ligand 1 (PD-L1) was associated with chemoresistance of cancer. However, there were little reports about the function of PD-L1 involved in chemoresistance of ovarian cancer. In our study, cisplatin (DDP)-resistant SKOV3 and A2780 ovarian cancer cell lines (SKOV3/DDP and A2780/DDP) were established. We found that the expression of PD-L1 was increased and miR-34a-5p was decreased in DDP-resistant cells. PD-L1 silencing inhibited chemoresistance of DDP-resistant ovarian cancer cells to DDP, as evidenced by decreased proliferation, G1-phase cell cycle arrest and increased apoptosis. Western blot assay showed that in the presence of DDP, PD-L1 silencing decreased multidrug resistance protein 1 and Cyclin D1 protein levels, whereas increased cleaved-caspase-3 and cleaved-PARP protein levels in these cells. Moreover, we demonstrated that miR-34a-5p negatively regulated the expression of PD-L1 by targeting its 3'-untranslated region. The effects of miR-34a-5p mimic on DDP-treated SKOV3/DDP cells were reversed by the overexpression of PD-L1. Moreover, the tumorigenicity of DDP-resistant ovarian cancer cells in nude mice treated with DDP was attenuated by miR-34a-5p in vivo. The combined data indicate that miR-34a-5p/PD-L1 axis regulates DDP chemoresistance of ovarian cancer cells, providing a deeper insight into the treatment for ovarian cancer.

Abstract GMM-059: SHEAR STRESS DOWNREGULATION OF MIR-199A-3P DRIVES CHEMORESISTANCE IN OVARIAN CANCER CELLS

Abstract Ovarian cancer is leading cause of deaths among all gynecological malignancies. The presence of intrinsic and acquired drug resistance are major challenges in the treatment and clinical management of ovarian cancer. Ovarian cancer cells typically cluster into tumor spheroids and float in the ascitic fluid, which are characteristic of the aggressiveness of these tumor cells. We have recently developed a three-dimensional microfluidic platform with tumor spheroids and continuous fluidic flow to closely emulate the physiological condition in the ascites of ovarian cancer patients. Using this model, we showed for the first time that clinically relevant levels of ascitic shear stress induced drug resistance in ovarian tumor spheroids. Such chemoresistance was mediated through the increased expression of ABC-binding cassette transporter G2 and P-glycoprotein. By profiling the microRNAs (miRNAs) expression patterns under flow conditions, we identified miR-199a-3p as a critical mechanosensitive miRNA that was downregulated under shear stress through regulating the miRNA biogenesis machinery. miR-199a-3p expression was found to be inversely correlated with enhanced drug resistance properties and chemoresistant ovarian cancer sublines. Ectopic expression of miRNA-199a-3p could reverse the shear stress-induced expression of ABC-binding cassette transporter G2 and P-glycoprotein in ovarian tumor spheroids, confirming that the effect was miR-199a-3p specific. Taken together, these findings highlight the importance of shear stress-mediated decrease of miR-199a-3p in the regulation of drug response in ovarian cancer, which provide new insights in the understanding of cancer biology and potential effective treatment. Citation Format: Shan-Shan Li, Carman K. M. Ip, Ho-Cheung Shum, Alice S. T. Wong. SHEAR STRESS DOWNREGULATION OF MIR-199A-3P DRIVES CHEMORESISTANCE IN OVARIAN CANCER CELLS [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr GMM-059.

Abstract AP32: THE ROLE OF NFAT3 IN OVARIAN CANCER QUIESCENCE AND CHEMOTHERAPY RESISTANCE

Abstract Despite the fact that the majority of patients with ovarian cancer will have a complete clinical remission with combined surgical/chemotherapeutic approaches, Epithelial Ovarian Cancer (EOC) is the fifth most common cause of cancer-related death in American women, with the third highest mortality:incidence ratio. The majority of deaths from ovarian cancer are related to disease recurrence and the subsequent development of ultimately fatal chemotherapy-resistant disease. Elucidating mechanisms of chemoresistance in ovarian cancer cells may identify critical therapeutic targets to prevent or treat relapsed ovarian cancer. One feature that might contribute to the chemotherapy resistance is quiescence. Quiescence describes a reversible non-proliferative cell state. As such, quiescent cells have reduced susceptibility to chemotherapeutics which target rapidly proliferating cells. Indeed, quiescence is a known mechanism of chemotherapy resistance of normal stem cells. In normal stem cells quiescence is mediated by the NFAT family of transcription factors. Unfortunately, very little is known about the factors that mediate ovarian cancer cell quiescence. Using qRT-PCR, we evaluated the expression of NFAT family members in ovarian cancer cells. We found NFAT3 to be enriched in patient ovarian cancer stem-like cells (CSLC) compared to bulk cancer cells. Treatment of EOC cells with cisplatin chemotherapy resulted in a nuclear translocation of NFAT3 and increase in NFAT3 transcriptional activity. To directly investigate the functional role of NFAT3 in ovarian cancer, we created ovarian cancer cell lines expressing constitutively nuclear/active (cNFAT3) or inducible constitutively active (IcNFAT3) NFAT3. We found that while cNFAT3 expression in ovarian cancer cells did not impact cell viability, senescence or apoptosis, cNFAT3 expression profoundly restricted ovarian cancer cell proliferation, with a 3-fold decreased cell division rates, and cellular arrest in the G0 phase of the cell cycle. Consistent with a quiescent cell phenotype, this was associated with a 10% decrease in cell size, and a 25% decrease in total cellular RNA. Induction of cNFAT3 expression in vivo resulted in tumor growth arrest. This growth arrest resulted in chemotherapy resistance such that cNFAT3 tumors treated with high dose of chemotherapy rapidly expanded after cNFAT3 inactivation. Furthermore, NFAT inhibition with the peptide inhibitor VIVIT enhance chemotherapy response in vitro and in vivo. Taken together, our data suggests NFAT3 drives a quiescent state in CSLC and thereby mediates chemoresistance. Thus NFAT3 represents a therapeutic target to both overcome chemotherapy resistance in quiescent cancer cells and to restrict the growth of therapy-resistant disease. Citation Format: Alex J Cole, Mangala Iyengar, Patrick O'Hayer, Kun Yang, Tara Sebastian, Lan Coffman, Ronald J Buckanovich. THE ROLE OF NFAT3 IN OVARIAN CANCER QUIESCENCE AND CHEMOTHERAPY RESISTANCE [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr AP32.

Targeting Ovarian Cancer Cell Cytotoxic Drug Resistance Phenotype with Xanthium strumarium L. Extract.

Emerging drugs aim at targeting the genomic integrity and replication machinery in ovarian cancer. While the antiproliferative activity of Xanthium strumarium L. extract (XFC), a traditional herbal medicine, is believed to alter the mitotic apparatus of Chinese hamster ovary epithelial cells, its capacity to target and overcome the chemoresistance phenotype in ovarian cancer is unknown. Among the cancer cell lines tested, we found that the best proliferation inhibitory effect for XFC was against ovarian cancer cells and ranged from 30 to 35 μg/mL. XFC efficiently targeted both the cytotoxic drug chemoresistance phenotype of SKOV-3 cells and of the chemosensitive ES-2 cells. Early apoptosis and late apoptosis were effectively induced by XFC extract in ES-2 cells, whereas late apoptosis and necrosis events were triggered in SKOV-3 cells. Cell cycling regulation was trapped by XFC extract in the G2/M phase in both the ES-2 and SKOV-3 cell models. This effect was, in part, attributable to increased dose-dependent tubulin polymerization, which was increased in SKOV-3 cells. Whereas XFC extract triggered poly (ADP-Ribose) polymerase (PARP) cleavage in both ES-2 and SKOV-3 cells, it only lowered Nrf2 in ES-2 cells and phosphorylated Akt levels in SKOV-3 cells. Interestingly, cell cycling regulators Cdk4, Cyclin D3, and p27 were all decreased in SKOV-3 cells. XFC extracts were effective in inhibiting in vitro migration in both ovarian cancer cell models. Our data support the potential anticancer targeting of chemoresistant human ovarian cancer cells phenotype by XFC extract.

The exosome-mediated autocrine and paracrine actions of plasma gelsolin in ovarian cancer chemoresistance

Ovarian cancer (OVCA) is the most lethal gynecological cancer, due predominantly to late presentation, high recurrence rate and common chemoresistance development. The expression of the actin-associated protein cytosolic gelsolin (GSN) regulates the gynecological cancer cell fate resulting in dysregulation in chemosensitivity. In this study, we report that elevated expression of plasma gelsolin (pGSN), a secreted isoform of GSN and expressed from the same GSN gene, correlates with poorer overall survival and relapse-free survival in patients with OVCA. In addition, it is highly expressed and secreted in chemoresistant OVCA cells than its chemosensitive counterparts. pGSN, secreted and transported via exosomes (Ex-pGSN), upregulates HIF1α–mediated pGSN expression in chemoresistant OVCA cells in an autocrine manner as well as confers cisplatin resistance in otherwise chemosensitive OVCA cells. These findings support our hypothesis that exosomal pGSN promotes OVCA cell survival through both autocrine and paracrine mechanisms that transform chemosensitive cells to resistant counterparts. Specifically, pGSN transported via exosomes is a determinant of chemoresistance in OVCA.

Binding mode of Pyridoclax to myeloid cell leukemia-1 (Mcl-1) revealed by nuclear magnetic resonance spectroscopy, docking and molecular dynamics approaches

Myeloid cell leukemia-1 (Mcl-1) is an anti-apoptotic member of the Bcl-2 family proteins. Its amplification is one of the most frequent genetic aberrations found in human cancers. Pyridoclax, a promising BH3 mimetic inhibitor, interacts directly with Mcl-1 and induces massive apoptosis at a concentration of 15 µM in combination with anti-Bcl-xL strategies in chemo-resistant ovarian cancer cell lines. In this study, a combined experimental and theoretical approach was used to investigate the binding mode of Pyridoclax to Mcl-1. The representative poses generated from dynamics simulations compared with NMR data revealed: (i) Pyridoclax bound to P1 and P2 pockets of Mcl-1 BH3 binding groove through its styryl and methyl groups establishing mainly hydrophobic contacts, (ii) one of the ending pyridines interacts through electrostatic interaction with K234 side chain, a negatively charged residue present only in this position in Mcl-1. Communicated by Ramaswamy H. Sarma

First person – Maitreyi Rathod and Sushmita Chatterjee

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Maitreyi Rathod and Sushmita Chatterjee are co-first authors on ‘Mannose glycosylation is an integral step for NIS localization and function in human breast cancer cells’, published in JCS. Maitreyi conducted the research described in this article while a PhD student in Dr Abhijit De's lab at the ACTREC, Tata Memorial Centre, Navi Mumbai, India. Sushmita is now a a postdoctoral fellow in Prof. Dan Peer's lab at Tel Aviv University, Israel, investigating the use of RNAi in ovarian cancer and in order to target chemo-resistant ovarian cancer cells.

Matrine inhibits the development and progression of ovarian cancer by repressing cancer associated phosphorylation signaling pathways

Ovarian cancer remains the most lethal gynecologic malignancy with late detection and acquired chemoresistance. Advanced understanding of the pathophysiology and novel treatment strategies are urgently required. A growing body of proteomic investigations suggest that phosphorylation has a pivotal role in the regulation of ovarian cancer associated signaling pathways. Matrine has been extensively studied for its potent anti-tumor activities. However, its effect on ovarian cancer cells and underlying molecular mechanisms remain unclear. Herein we showed that matrine treatment inhibited the development and progression of ovarian cancer cells by regulating proliferation, apoptosis, autophagy, invasion and angiogenesis. Matrine treatment retarded the cancer associated signaling transduction by decreasing the phosphorylation levels of ERK1/2, MEK1/2, PI3K, Akt, mTOR, FAK, RhoA, VEGFR2, and Tie2 in vitro and in vivo. Moreover, matrine showed excellent antitumor effect on chemoresistant ovarian cancer cells. No obvious toxic side effects were observed in matrine-administrated mice. As the natural agent, matrine has the potential to be the targeting drug against ovarian cancer cells with the advantages of overcoming the chemotherapy resistance and decreasing the toxic side effects.

ST3Gal3 confers paclitaxel‑mediated chemoresistance in ovarian cancer cells by attenuating caspase‑8/3 signaling.

The aberrant expression of sialyltransferase has a role in cell differentiation, neoplastic transformation and the progression of various types of cancer. Our previous studies have shown that high expression of β-galactoside-α2,3-sialyltransferase III (ST3Gal3) in the metastatic ovarian cancer cell line HO8910PM attenuated cisplatin-induced apoptosis. The present study demonstrated that paclitaxel-induced chemoresistance in ovarian cancer cells upregulated the expression of ST3Gal3 and reduced the activity of caspase-8/3. The results of the present study revealed that the endogenous levels of ST3Gal3 mRNA and protein were significantly higher in HO8910PM cells compared with SKOV3 cells. A higher expression of ST3Gal3 was correlated with an increased resistance to paclitaxel, while the downregulation of ST3Gal3 resulted in paclitaxel-induced apoptosis. Paclitaxel upregulated ST3Gal3 expression at the mRNA and protein levels in HO8910PM cells, but not in SKOV3 cells. Silencing of ST3Gal3 by small interfering RNA reversed these effects and increased the protein levels of caspase-8/3, which may contribute to paclitaxel-induced apoptosis. The results of the present study suggested that ST3Gal3 was a target for paclitaxel-related resistance during ovarian cancer chemotherapy.

P53 Promotes chemoresponsiveness by regulating hexokinase II gene transcription and metabolic reprogramming in epithelial ovarian cancer.

Metabolic reprogramming (including the Warburg effect) is a hallmark of cancer, yet the association between the altered metabolism and chemoresistance remains elusive. Hexokinase II (HKII) is a key metabolic enzyme and is upregulated in multiple cancers. In this study, we examined the impact of targeting metabolism via silencing of HKII on chemoresistance in ovarian cancer (OVCA). In addition, the regulatory molecular mechanism of tumor metabolism was examined using gain- and loss-of-function approaches in epithelial OVCA cell lines of various histological subtypes. We demonstrated that cisplatin (CDDP)-induced p53-mediated HKII downregulation is a determinant of chemosensitivity in OVCA. Silencing of HKII sensitized chemoresistant OVCA cells to apoptosis in a p53-dependent manner. As a negative regulator, p53 suppressed HKII transcription by promoter binding and decreased glycolysis. Pyruvate dehydrogenase kinase-1 (PDK1) is a key regulator of cell proliferation involved in Akt signaling axis. Our Gene Expression Profiling Interactive Analysis (GEPIA) and molecular studies also revealed that PDK1, an upstream activator strongly correlates with HKII expression and regulates its metabolic activity. Finally, we demonstrated that the clinically approved drug metformin sensitizes chemoresistant OVCA cells to CDDP via PDK1-HKII pathway. Collectively, our data implicate that p53--PDK1-HKII axis is a central regulatory component of metabolism conferring chemoresistance in OVCA.

MiR-1307 influences the chemotherapeutic sensitivity in ovarian cancer cells through the regulation of the CIC transcriptional repressor

BackgroundExtended from our previously observation that expression of miR-1307 in chemoresistant primary ovarian cancer tissues is elevated, here we are aiming to dissect the function of miR-1307 and its predicted target gene, CIC (capicua transcriptional repressor), in ovarian cancer chemotherapy. MethodsWe evaluated the expression of miR-1307 and CIC in chemoresistant and chemosensitive ovarian cancer tissues and cells by real time-PCR and western blot. We used chemoresistant/chemosensitive cells with miR-1307 suppression/overexpression to study the biological effects of miR-1307 by MTT and flow cytometer. Dual luciferase reporter gene assay was used to validate direct binding between miR-1307 and the 3′-UTR of CIC. Real-time PCR and western blot analyses, MTT and flow cytometry were used to reveal the biological effects of miR-1307 and CIC, as well as their regulation. ResultsWe found that miR-1307 affects cell cycle dynamics, cell viability in ovarian cancer cells. In addition, its expression level can influence chemosensitivity to paclitaxel in ovarian cancer cells. We also validate that CIC is a downstream target of miR-1307 via its regulation on 3’-UTR of CIC gene and ETV4 and ETV5 are also regulated by miR-1307/CIC axis. ConclusionsOur data suggested that miR-1307 may be involved in the resistance of ovarian cancer to chemotherapy drugs via regulation of CIC, and should be further explored as a potential therapeutic target.

4-Methylumbelliferone Inhibits Cancer Stem Cell Activation and Overcomes Chemoresistance in Ovarian Cancer.

We have recently shown that the extracellular matrix molecule hyaluronan (HA) plays a role in the development of ovarian cancer chemoresistance. This present study determined if HA production is increased in chemotherapy-resistant ovarian cancers and if the HA inhibitor 4-methylubelliferone (4-MU) can overcome chemoresistance to the chemotherapeutic drug carboplatin (CBP) and inhibit spheroid formation and the expression of cancer stem cell (CSC) markers. We additionally assessed whether 4-MU could inhibit in vivo invasion of chemoresistant primary ovarian cancer cells in the chicken embryo chorioallantoic membrane (CAM) assay. The expression of the HA synthases HAS2 and HAS3 was significantly increased in chemoresistant compared to chemosensitive primary ovarian cancer cells isolated from patient ascites. 4-MU significantly inhibited HA production, cell survival, and spheroid formation of chemoresistant serous ovarian cancer cells. In combination with CBP, 4-MU treatment significantly decreased ovarian cancer cell survival and increased apoptosis of chemoresistant primary cells compared to CBP alone. 4-MU significantly reduced spheroid formation, expression of CSC markers ALDH1A1 and ABCG2 in primary cell spheroid cultures, and ALDH1 immunostaining in patient-derived tissue explant assays following treatment with CBP. Furthermore, 4-MU was very effective at inhibiting in vivo invasion of chemoresistant primary cells in CAM assays. Inhibition of HA is therefore a promising new strategy to overcome chemoresistance and to improve ovarian cancer survival.

Analysis of Differentially Expressed MicroRNAs and Circulating Tumor Cells as Predictive Biomarkers of Platinum Chemoresistance in Primary Ovarian Carcinomas: A Prospective Study

Lesson Learned.Circulating tumor cells, microRNA markers, or other biomarkers merit examination as part of correlative scientific analyses in prospective clinical trials.Background.Platinum chemotherapy resistance occurs in approximately 25% of patients with ovarian carcinoma; however, no biomarkers of ovarian carcinoma chemoresistance have been validated. We performed a prospective trial designed to identify tumor‐based predictive biomarkers of platinum resistance.Methods.Tumor specimens were collected from 29 women with newly diagnosed histopathologically proven primary ovarian carcinoma. Of these, 23 women had specimens accessible for assessment and outcome data available regarding chemosensitive versus chemoresistance status via review of the medical record. Tumor slices were stained with antibodies against two microRNAs (miRNAs 29b and 199a) differentially expressed in chemoresistant ovarian cancer cell lines. Additionally, blood samples obtained at the time of diagnosis were analyzed for the presence of circulating tumor cells (CTCs).Results.The average age of the patients was 64 years, and 82.6% had high‐grade epithelial carcinomas. The baseline median CA‐125 was 464 (range 32–2,782). No statistically significant differences were observed in miR29b or 199a expression in platinum‐resistant/refractory versus platinum‐sensitive tumors. Furthermore, the presence of CTCs was not found to be statistically significantly predictive of eventual platinum resistance.Conclusion.Our analysis showed no differences in miR29b and 199a expression, and differences in baseline CTCs in women with newly diagnosed ovarian tumors were not statistically significant.