MDR gene expression analysis of six drug-resistant ovarian cancer cell lines

Inhibition of ALDH1A1 activity decreases expression of drug transporters and reduces chemotherapy resistance in ovarian cancer cell lines

The high mortality of ovarian cancer patients results from the failure of treatment caused by the inherent or acquired chemotherapy drug resistance. It was reported that overexpression of aldehyde dehydrogenase A1 (ALDH1A1) in cancer cells can be responsible for the development of drug resistance. To add the high expression of the drug transporter proteins the ALDHA1 is considered as a molecular target in cancer therapy. Therefore, we analysed drug-resistant ovarian cancer cell lines according to ALDHA1 expression and the association with drug resistance. The expression of ALDH1A1, P-glycoprotein (P-gp) or breast cancer resistance protein (BCRP) was determined using a microarray and confirmed by Q-PCR, western blot and fluorescence analysis. ALDH1A1 activity was determined using an Aldefluor assay. The impact of all-trans retinoic acid (ATRA) and diethylaminobenzaldehyde (DEAB) on chemotherapy resistance was assessed by the MTT chemosensitivity assay. The most abundant expression of ALDH1A1 was noted in paclitaxel- and topotecan-resistant cell lines where two populations of ALDH-positive and ALDH-negative cells could be observed. Those cell lines also revealed the overexpression of P-gp and BCRP respectively, and were able to form spheres in non-adherent conditions. Pre-treatment with ATRA and DEAB reduced chemotherapy resistance in both cell lines. ATRA treatment led to downregulation of the ALDH1A1, P-gp and BCRP proteins. DEAB treatment led to downregulation of the P-gp protein and BCRP transcript and protein. Our results indicate that ALDH1A1-positive cancer cells can be responsible for drug resistance development in ovarian cancer. Developing more specific ALDH1A1 inhibitors can increase chemotherapy effectiveness in ovarian cancer.

Increased Expression of Several Collagen Genes is Associated with Drug Resistance in Ovarian Cancer Cell Lines

Ovarian cancer is the most lethal gynaecological cancer. The main reason for the high mortality among ovarian cancer patients is the development of drug resistance. The expression of collagen genes by cancer cells can increase drug resistance by inhibiting the penetration of the drug into the cancer tissue as well as increase apoptosis resistance. In this study, we present data that shows differential expression levels of collagen genes and proteins in cisplatin- (CIS), paclitaxel- (PAC), doxorubicin- (DOX), topotecan- (TOP), vincristine- (VIN) and methotrexate- (MTX) resistant ovarian cancer cell lines. Quantitative real-time polymerase chain reactions were performed to determine the mRNA levels. Protein expression was detected using Western blot and immunocytochemistry assays. In the drug resistant cell lines, we observed the upregulation of eight collagen genes at the mRNA level and based on these expression levels, we divided the collagen genes into the following three groups:

1. Genes with less than a 50-fold increase in expression: COL1A1, COL5A2, COL12A1 and COL17A1. 2. Genes with greater than a 50-fold increase in expression: COL1A2, COL15A1 and COL21A1. 3. Gene with a very high level of expression: COL3A1. Expression of collagen (COL) proteins from groups 2 and 3 were also confirmed using immunocytochemistry. Western blot analysis showed very high expression levels of COL3A1 protein, and immunocytochemistry analysis showed the presence of extracellular COL3A1 in the W1TR cell line. The cells mainly responsible for the extracellular COL3A1 production are aldehyde dehydrogenase-1A1 (ALDH1A1) positive cells. All correlations between the types of cytostatic drugs and the expression levels of different COL genes were studied, and our results suggest that the expression of fibrillar collagens may be involved in the TOP and PAC resistance of the ovarian cancer cells. The expression pattern of COL genes provide a preliminary view into the role of these proteins in cytostatic drug resistance of cancer cells. The exact role of these COL genes in drug resistance requires further investigation.

The Combination of Vemurafenib and Procaspase-3 Activation Is Synergistic in Mutant BRAF Melanomas

The development of vemurafenib resistance limits the long-term efficacy of this drug for treatment of metastatic melanomas with the (V600E)BRAF mutation. Inhibition of downstream MAPK signaling with vemurafenib induces apoptotic cell death mediated by caspase-3, suggesting that addition of a procaspase-3 activator could enhance anticancer effects. Here, we show that the combination of PAC-1, a procaspase-activating compound, and vemurafenib is highly synergistic in enhancing caspase-3 activity and apoptotic cell death in melanoma cell lines harboring the (V600E)BRAF mutation. In vivo, the combination displays a favorable safety profile in mice and exerts significant antitumor effects. We further demonstrate that addition of PAC-1 to the clinically useful combination of vemurafenib and a MEK inhibitor, trametinib, starkly enhances the caspase-3 activity and proapoptotic effect of the combination. Moreover, addition of low concentration PAC-1 also delays the regrowth of cells following treatment with vemurafenib. Finally, PAC-1 remains potent against vemurafenib-resistant A375VR cells in cell culture and synergizes with vemurafenib to exert antitumor effects on A375VR cell growth in vivo Collectively, our data suggest that inhibition of MAPK signaling combined with concurrent procaspase-3 activation is an effective strategy to enhance the antitumor activity of vemurafenib and mitigate the development of resistance. Mol Cancer Ther; 15(8); 1859-69. ©2016 AACR.

Guizhi Fuling Wan, a Traditional Chinese Herbal Formula, Sensitizes Cisplatin-Resistant Human Ovarian Cancer Cells through Inactivation of the PI3K/AKT/mTOR Pathway

The aim of the study was to explore the possible mechanisms that Guizhi Fuling Wan (GFW) enhances the sensitivity of the SKOV3/DDP ovarian cancer cells and the resistant xenograft tumours to cisplatin. Rat medicated sera containing GFW were prepared by administering GFW to rats, and the primary bioactive constituents of the sera were gallic acid, paeonol, and paeoniflorin analysed by HPLC/QqQ MS. Cell counting kit-8 analysis was shown that coincubation of the sera with cisplatin/paclitaxel enhanced significantly the cytotoxic effect of cisplatin or paclitaxel in SKOV3/DDP cells. The presence of the rat medicated sera containing GFW resulted in an increase in rhodamine 123 accumulation by flow cytometric assays and a decrease in the protein levels of P-gp, phosphorylation of AKT at Ser473, and mTOR in a dose-dependent manner in SKOV3/DDP cells by western blot analysis, but the sera had no effect on the protein levels of PI3K p110α and total AKT. The low dose of GFW enhanced the anticancer efficacy of cisplatin and paclitaxel treatment in resistant SKOV3/DDP xenograft tumours. GFW could sensitize cisplatin-resistant SKOV3/DDP cells by inhibiting the protein level and function of P-gp, which may be medicated through inactivation of the PI3K/AKT/mTOR pathway.

Effect of Procyanidin-rich Extract from Natural Cocoa Powder on Cellular Viability, Cell Cycle Progression, and Chemoresistance in Human Epithelial Ovarian Carcinoma Cell Lines

Background:

Over the last 400 years, cocoa and chocolate have been described as having potential medicinal value, being consumed as a beverage or eaten as food. Concentration–dependant, antiproliferation, and cytotoxic effects of some of their polyphenolic constituents have been demonstrated against various cancers. Such an effect remains to be demonstrated in ovarian cancer

Objective:

To investigate the effect of cocoa procyanidins against ovarian cancer in vitro using OAW42 and OVCAR3 cell lines.

Materials and Methods:

Cocoa procyanidins were extracted and enriched from non alkalized cocoa powder. The polyphenolic content and antioxidant activity were determined. Effect on cell viability was determined after the treatment with ≤1000 μg/mL cocoa procyanidin-rich extract on OAW42 and OVCAR3 and normal human dermal fibroblasts. Similarly, chemosensitization effect was determined by pretreating cancer cell lines with extract followed by doxorubicin hydrochloride treatment. The effect of treatment on cell cycle and P-glycoprotein (P-gp) expression was determined using flow cytometry.

Results:

The cocoa extract showed high polyphenolic content and antioxidant activity. Treatment with extract caused cytotoxicity and chemosensitization in OAW42 and OVCAR3 cell lines. Normal dermal fibroblasts showed an increase in cell viability post treatment with extract. Treatment with extract affected the cell cycle and an increasing percentage of cells in hypodiploid sub-G₁/G₀ phase was observed. Treatment of OVCAR3 with the extract caused reduction of P-gp expression.

Conclusion:

Cocoa procyanidins were found to be selectively cytotoxic against epithelial ovarian cancer, interfered with the normal cell cycle and sensitized cells to subsequent chemotherapeutic treatment. Chemosensitization was found to be associated with P-gp reduction in OVCAR3 cells.

SUMMARY

Among the naturally occurring flavonoids, procyanidins have been shown to be effective against cancers

Non alkalized cocoa powder is one of the richest sources of procyanidins

Cocoa procyanidin-rich extract (CPRE) caused cytotoxicity and chemosensitization in ovarian carcinoma cell lines OAW42 and OVCAR3

CPRE affected normal cell cycle progression

CPRE also downregulated P-glycoprotein, which mediates chemoresistance in multidrug-resistant OVCAR3 cell line.

Abbreviations used: P-gp: P-glycoprotein, CPRE: Cocoa procyanidin rich extract, DMAC: 4-dimethylaminocinnamaldehyde, DPPH: Diphenylpicrylhydrazyl, ABTS: 2,2’;-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid), PI: Propidium iodide, FITC: Fluorescein isothiocyanate, MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, TLC: Thin layer chromatography, HPTLC: High-performance thin layer chromatography.

A preliminary study on epigenetic regulation of Acanthopanax senticosus in leukemia cell lines

Conventional chemotherapy for leukemia inevitably causes systemic toxicity. Acanthopanax senticosus, a naturally occurring herb used in traditional Chinese medicine, has been found to be a multipotent bioflavonoid with great potential in the prevention and treatment of malignant diseases. However, the mechanism underlying the action of A. senticosus in epigenetic regulation is poorly understood. In the study described here, we focused on the efficacy of A. senticosus in inducing apoptosis of leukemia cells and a possible mechanism. By evaluating the inhibition ratio and morphologic changes, we found that A. senticosus can inhibit growth and induce apoptosis of human leukemia HL-60 and HL60/ADM cells in a dose- and time-dependent manner. Furthermore, A. senticosus induced Fas ligand (FasL) expression and blocked the cell cycle in S phase. In addition, A. senticosus exhibited a potential for inhibition of histone deacetylase (HADC), which contributes to histone acetylation. It possibly resulted in the promotion of the expression of FasL. It is suggested that A. senticosus could be recognized as a new HDAC inhibitor which was able to reactivate aberrantly silenced genes. We discuss the clinical aspects of using A. senticosus for treatment of leukemia.

Effect of brefeldin A and castanospermine on resistant cell lines as supplements in anticancer therapy

In the present study, we analyzed the influence of brefeldin A (BFA) and castanospermine (CAS) on the activity, stability and localization of P-glycoprotein (Pgp) and breast cancer resistance protein (BCRP) in various resistant cell lines. The impact of BFA and CAS on cell viability was assessed using the MTT test. Western blotting (WB) was performed to assess the effect of the inhibitors on the expression of the investigated proteins. Immunofluorescence was employed to assess the effect of BFA and CAS on the cellular localization of the proteins. Flow cytometry was used to verify the functional role of inhibitors on drug uptake and efflux. The MTT test showed that BFA had a significant effect on cell viability in LoVo/Dx and W1PR cell lines. WB analysis demonstrated that BFA partially blocked Pgp N-glycosylation and induced BCRP degradation and CASP 3-dependent apoptosis in W1TR cells; however, the BFA activity was p53-independent. CAS had no effect on the stability of Pgp but increased the level of non-glycosylated BCRP. The expression of p53 protein decreased in all of the cells that were treated with CAS. Immunofluorescence revealed that BFA caused a more granular Pgp signal in W1PR and BCRP in A2780T1 cells. Furthermore, BFA caused morphological changes in LoVo/Dx and W1TR cell lines. CAS also induced a granular signal in all of the cell lines, except W1TR. The flow cytometry showed higher dye accumulation in sensitive cell lines. We observed an increase in the mean fluorescence intensity (MFI) of Rho123 in LoVo/Dx cells treated with BFA and CAS, but no differences were observed in W1PR. BFA had no effect on the MFI of W1TR, but CAS led to an increase in the level of intracellular H33342 in W1TR and A2780T1 cells. These results suggest that these compounds are likely to be useful as supplements in anticancer therapy.

MicroRNA-186 induces sensitivity of ovarian cancer cells to paclitaxel and cisplatin by targeting ABCB1

Background

Recent studies have shown that microRNAs may regulate the ABCB1 gene (ATP-binding cassette, sub-family B [MDR/TAP], member 1). Computational programs have predicted that the 3’-untranslated region (3’-UTR) of ABCB1 contains a potential miRNA-binding site for miR-186. Here, we investigated the role of miR-186 in sensitizing ovarian cancer cells to paclitaxel and cisplatin.

Results

Human ovarian carcinoma cell lines OVCAR3, A2780, A2780/DDP, and A2780/Taxol were exposed to paclitaxel or cisplatin with or without miR-186 transfection, and cell viability was determined by MTT assay. Reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis were used to assess the MDR1, GST-π, and MRP1 expression levels. Dual-luciferase reporter assay was used to reveal the correlation between miR-186 and ABCB1. Lower miR-186 while higher MDR1 and GST-π mRNA expression levels were found in the A2780/Taxol and A2780/DDP cells than in the A2780 cells. After miR-186 transfection, all the cell lines showed increased sensitivity to paclitaxel and cisplatin. MiR-186 transfection induced apoptosis while anti-miR-186 transfection reduced apoptosis. The dual-luciferase reporter assay verified that that miR-186 combined with the 3’-untranslated region (UTR) of ABCB1. MDR1 and GST-π mRNA and protein expression levels were downregulated after transfection with miR-186 but upregulated following anti-miR-186 transfection compared to the mock and negative control cancer cells; however, the MRP1 expression levels did not significantly differ among the groups.

Conclusion

Our results are the first to demonstrate that miR-186 may sensitize ovarian cancer cell to paclitaxel and cisplatin by targeting ABCB1 and modulating the expression of GST-π.

Electronic supplementary material

The online version of this article (doi:10.1186/s13048-015-0207-6) contains supplementary material, which is available to authorized users.

Cancer Chemopreventive Potential of Procyanidin

Chemoprevention entails the use of synthetic agents or naturally occurring dietary phytochemicals to prevent cancer development and progression. One promising chemopreventive agent, procyanidin, is a naturally occurring polyphenol that exhibits beneficial health effects including anti-inflammatory, antiproliferative, and antitumor activities. Currently, many preclinical reports suggest procyanidin as a promising lead compound for cancer prevention and treatment. As a potential anticancer agent, procyanidin has been shown to inhibit the proliferation of various cancer cells in “in vitro and in vivo”. Procyanidin has numerous targets, many of which are components of intracellular signaling pathways, including proinflammatory mediators, regulators of cell survival and apoptosis, and angiogenic and metastatic mediators, and modulates a set of upstream kinases, transcription factors, and their regulators. Although remarkable progress characterizing the molecular mechanisms and targets underlying the anticancer properties of procyanidin has been made in the past decade, the chemopreventive targets or biomarkers of procyanidin action have not been completely elucidated. This review focuses on the apoptosis and tumor inhibitory effects of procyanidin with respect to its bioavailability.

MicroRNA-133b targets glutathione S-transferase π expression to increase ovarian cancer cell sensitivity to chemotherapy drugs

Background

Accumulating studies reveal that aberrant microRNA (miRNA) expression can affect the development of chemotherapy drug resistance by modulating the expression of relevant target proteins. The aim of this study was to investigate the role of miR-133b in the development of drug resistance in ovarian cancer cells.

Methods

We examined the levels of miR-133b expression in ovarian carcinoma tissues and the human ovarian carcinoma cell lines (A2780, A2780/DDP and A2780/Taxol, respectively). We determined the cell viability of these cell lines treated with cisplatin or paclitaxel in the presence or absence of miR-133b or anti-miR-133b transfection using the MTT assay. Reverse transcription polymerase chain reaction and Western blotting were used to assess the mRNA and protein expression levels of two drug-resistance-related genes: glutathione S-transferase (GST)-π and multidrug resistance protein 1 (MDR1). The dual-luciferase reporter assay was used to detect the promoter activity of GST-π in the presence and absence of miR-133b.

Results

The expression of miR-133b was significantly lower in primary resistant ovarian carcinomas than in the chemotherapy-sensitive carcinomas (P<0.05), and the same results were found in primary resistant ovarian cell lines (A2780/Taxol and A2780/DDP) compared to the chemotherapy-sensitive cell line (A2780; P<0.05). Following miR-133b transfection, four cell lines showed increased sensitivity to paclitaxel and cisplatin, while anti-miR-133b transfection reduced cell sensitivity to paclitaxel and cisplatin. Dual-luciferase reporter assay showed that miR-133b interacted with the 3′-untranslated region of GST-π. Compared to controls, the mRNA and protein levels of MDR1 and GST-π were downregulated after miR-133b transfection and upregulated after anti-miR-133b transfection.

Conclusion

MicroRNA-133b may reduce ovarian cancer drug resistance by silencing the expression of the drug-resistance-related proteins, GST-π and MDR1. In future, the combination of miR-133b with chemotherapy agents may prevent the development of drug resistance in ovarian cancers.

Inhibition of protein glycosylation reverses the MDR phenotype of cancer cell lines

BACKGROUND

Multidrug resistance proteins are one of the most important factors that cause chemotherapy resistance, which in turn reduces therapeutic efficacy and survival for cancer patients. Tunicamycin is one of the most well-known inhibitors of N-glycosylation and is considered a powerful adjunct that can increase the effectiveness of many drugs. Tunicamycin blocks the first step of P-gp (glycoprotein P) and BCRP (breast cancer resistance protein) N-glycosylation, which is a very important modification for the activity and cellular localisation of these proteins.

METHODS

The effects of tunicamycin on ovarian and colorectal cancer cells were examined in multiple cell lines. The primary ovarian cancer cell line W1 and the established ovarian cancer cell line A2780 were compared against their drug-resistant derivatives W1TR/W1PR (TR: topotecan resistant; PR: paclitaxel resistant) and A2780T1 (topotecan resistant), respectively. We also compared the colorectal cancer cell line LoVo against its doxorubicin-resistant derivative LoVo/Dx. Cell viability was determined by the MTT assay. The glycopeptides were subjected to deglycosylation using the endoglycosidase PNGase F. A2780T1, LoVo/Dx and W1PR cells were treated with the protein degradation inhibitors MG132 and BMA. Protein expression was detected by western blot and immunocytochemistry.

RESULTS

In this study, we showed via the MTT assay that tunicamycin significantly decreased the viability of cancer cell lines that were co-treated with a chemotherapeutic drug. Western blot analysis showed that, in LoVo/Dx and W1PR cells, tunicamycin treatment resulted in the expression of a 70kDa P-gp protein instead of the mature 170kDa P-gp. Treatment with MG132 or BMA fully suppressed the effect of tunicamycin in the case of W1PR cells only. In tunicamycin-treated W1TR cells, the size of the BCRP protein did not differ from that of its native unglycosylated form. In tunicamycin-treated A2780T1 cells, BCRP expression was completely inhibited, but pre-treatment with MG132 or BMA suppressed the effect of tunicamycin. Immunocytochemistry analysis indicated that tunicamycin only affected the translocation of P-gp but not that of BCRP. After treatment, we observed higher P-gp expression in the cytoplasm than at the cell membrane.

CONCLUSIONS

Our results indicated that tunicamycin may enhance the effect of chemotherapy by interfering with the localisation and function of transporter proteins that are responsible for multidrug resistance.

Relationship between the expression of MDR1 in hepatocellular cancer and its biological behaviors

OBJECTIVE

By the detection of HBV infection, AFP and AST, the targets of biological behavior and the gene expression of multi-drug resistance gene 1 (MDR1) in hepatocellular carcinoma (HCC), we investigate characteristics of the expression of MDR1 in HCC and its relationship with HCC biological behavior.

METHODS

Using real-time fluorescence quantitative PCR (FQ-PCR) to detect the expressions of MDR1 in 102 samples of HCC tissue and 20 samples of non-cancerous tissue, we analyze the relationship between expressions of MDR1 and biological characteristics of HCC.

RESULTS

The expression of MDR1 in HCC is 0.55 ± 0.27, and in normal liver tissues is 0.23 ± 0.10, respectively. The expression in HCC is higher than it in normal liver tissue, the difference is statistically significant (P<0.05) and the difference between the expression and the HCC envelopes is statistically significant, and the expression increases along with the increase of Edmondson classification (P<0.05). HBV infection, AFP positive, the rise of AST, all these factors have positive correlations with the expression (r=0.463, 0.473, 0.299). In MDR1 expressions of HCC patients, the survival curve of the negative is higher than that of the positive, but the difference is not statistically significant.

CONCLUSION

There are drug resistance phenomena in HCC, MDR1 expression may play an important role in primary HCC drug resistance. HBV infection can be detected as a reference indicator of HCC chemotherapy resistance, plasma levels of AFP, AST can be used as a reference index change dynamic monitoring of MDR1 expression.

Dual roles of NRF2 in tumor prevention and progression: possible implications in cancer treatment

The cap'n'collar (CNC) family serves as cellular sensors of oxidative and electrophilic stresses and shares structural similarities including basic leucine zipper (bZIP) and CNC domains. They form heterodimers with small MAF proteins to regulate antioxidant and phase II enzymes through antioxidant response element (ARE)-mediated transactivation. Among the CNC family members, NRF2 is required for systemic protection against redox-mediated injury and carcinogenesis. On the other hand, NRF2 is activated by oncogenic pathways, metabolism, and hypoxia. Constitutive NRF2 activation is observed in a variety of human cancers and it is highly correlated with tumor progression and aggressiveness. In this review, we will discuss how NRF2 plays dual roles in cancer prevention and progression depending on the cellular context and environment. Therefore, a better understanding of NRF2 will be necessary to exploit this complex network of balancing antioxidant pathways to inhibit tumor progression.

MiR-489 modulates cisplatin resistance in human ovarian cancer cells by targeting Akt3

MicroRNAs are a conserved class of small noncoding RNA molecules that harbour the capacity to regulate protein-coding gene expression at the post-transcriptional level. In the current study, we show that miR-489 is downregulated in cisplatin (CDDP)-resistant ovarian cancer cells, SKOV3/CDDP and OVCAR3/CDDP cells. MiR-489 overexpression results in an inhibition of SKOV3 and OVCAR3 cell survival and cell growth after CDDP treatment and an induction of cell apoptosis. Inhibition of miR-489 yields the opposite results. In addition, miR-489 overexpression increases the sensitivity of SKOV3/CDDP and OVCAR3/CDDP cells to CDDP and inhibits their colony number. Akt3 is validated as a direct target of miR-489 in SKOV3, OVCAR3, SKOV3/CDDP and OVCAR3/CDDP cells. In addition, miR-489 suppresses Akt3 protein expression by binding sites on its 3'UTR. Knockdown of Akt3 results in a similar effect as that because of miR-489 overexpression; importantly, Akt3 silencing rescues the functions induced by miR-489. Furthermore, we also use the Akt3 inhibitor, MK-2206 2HCl, to determine the role of Akt3 in CDDP resistance. Our study showed that MK-2206 2HCl increased the sensitivity of SKOV3/CDDP and OVCAR3/CDDP cells to CDDP. Taken together, our results indicate that miR-489 inhibited CDDP resistance and cell growth, and promotes apoptosis by suppressing Akt3 expression. Furthermore, the identification of a novel miR-489-based pathway in CDDP-resistant ovarian cancer will facilitate the development of therapeutic strategies.

Molecular insights into the anti-cancer properties of traditional Tibetan medicine Yukyung Karne

BACKGROUND

Yukyung karne (YK) is a traditional Tibetan formulation used for many centuries for the treatment of ovarian cancer. However, the pharmacological basis of its anticancer property is not well understood. In the present study, the anticancer property of YK was investigated in cell culture.

METHODS

The growth inhibitory property of YK was evaluated in SKOV6, IHH, HepG2 and HEK293 cell lines using MTT assay. The pro-apoptotic activity of drug was analyzed by terminal deoxynuleotidyl transferase dUTP nick end labeling (TUNEL) and DNA fragmentation assays. Confocal microscopy was used to show the release of cytochrome c and its co-localization with mitochondria with the help of dsRed mitotracker in SKOV6 cells. The inhibition in cell proliferation was also visualized by confocal microscopy after BrDU incorporation. The activation of tumor suppressor p53 was evaluated by Western blotting while VEGF levels in culture supernatant were measured by a colorimetric method.

RESULTS

YK specifically and efficiently induced apoptotic killing of the human ovarian cancer SKOV6 cells as indicated by increased DNA fragmentation and nick end DNA labeling. Confocal microscopy suggested inhibition of cell proliferation and increase in cytochrome c release via perturbation in mitochondrial membrane potential (Δψm). Further, YK up-regulated the expression of tumor suppressor p53 and key cyclin-dependent kinase inhibitor p21, and inhibited VEGF secretion by cells. Interestingly, YK also exhibited a synergy with paclitaxel which is a well-known anti-cancer therapeutic drug.

CONCLUSIONS

The pharmacological properties of YK to impose growth arrest and trigger pro-apoptotic death in cells amply justify its usage in primary as well as adjunct therapy for ovarian cancer.

microRNA 490-3P enhances the drug-resistance of human ovarian cancer cells

BACKGROUND

MicroRNAs (miRNAs) are non-coding, single-stranded small RNAs that regulate gene expression negatively, which is involved in fundamental cellular processes. In this study, we investigated the role of miR-490-3P in the development of drug resistance in ovarian cancer cells.

METHODS

The human ovarian carcinoma cell line A2780 and A2780/Taxol were exposed to paclitaxel in the presence or absence of microRNA 490-3P transfection, after which cell viability were performed by CCK-8 assay. Reverse transcription polymerase chain reaction (RT-PCR) and western blotting were used to assess the mRNA and protein expression levels of GST-π, MDR1 or P-gp.

RESULTS

Our results showed higher miR-490-3P mRNA expression level in A2780/Taxol cells than in A2780 cells (p < 0.05). Following miR-490-3P transfection, both A2780 and A2780/Taxol cells showed decreased sensitivity to paclitaxel. The mRNA expression levels of MDR1, GST-π (p < 0.05) and protein expression levels of P-gp, GST-π were up-regulated [corrected] after miR-490-3P transfection in comparison to mock and negative control cancer cells.

CONCLUSION

Our results demonstrate for the first time that microRNA 490-3P may be involved in the development of drug resistance in ovarian cancer.

The inhibition of constitutive androstane receptor-mediated pathway enhances the effects of anticancer agents in ovarian cancer cells

BACKGROUND

Ovarian cancer is commonly treated with anticancer agents; however, many tumors become resistant. Resistance is regulated, in part, by P-glycoprotein, which is encoded by the gene multiple drug resistance 1 (MDR1) and functions as a transmembrane efflux pump for the elimination of anticancer agents. Constitutive androstane receptor (CAR) is a nuclear receptor that regulates drug metabolism through control of MDR1 and other genes.

PURPOSE

We examined whether the inhibition of CAR-mediated pathway could influence the cytotoxicity of three anticancer drugs, cisplatin, paclitaxel, and arsenic trioxide, in ovarian cancer cells.

RESULTS

We observed that the cell proliferation of several ovarian cell lines expressing CAR significantly increased when CITCO was combined with anticancer agents compared with any anticancer agent alone. The up-regulation of MDR1 and UGT1A1 by anticancer agents was further enhanced in the presence of CITCO. We confirmed that combining CITCO with anticancer agents induced significantly lower levels of apoptosis than those achieved with any single anticancer drug. CAR down-regulation by RNA interference caused a significant increase in cell growth inhibition and enhancement of apoptosis in the presence of anticancer agents. Combination of CITCO with any anticancer agents significantly enhanced CAR-mediated transcription compared with any anticancer agents alone and CAR down-regulation completely inhibited the transcription in the presence of CITCO and/or anticancer agents.

CONCLUSION

Inhibition of CAR pathway could be a novel therapeutic approach for the augmentation of sensitivity to anticancer agents, or to overcome resistance, in the treatment of ovarian cancer.

Sinomenine sensitizes multidrug-resistant colon cancer cells (Caco-2) to doxorubicin by downregulation of MDR-1 expression

Chemoresistance in multidrug-resistant (MDR) cells over expressing P-glycoprotein (P-gp) encoded by the MDR1 gene, is a major obstacle to successful chemotherapy for colorectal cancer. Previous studies have indicated that sinomenine can enhance the absorption of various P-gp substrates. In the present study, we investigated the effect of sinomenine on the chemoresistance in colon cancer cells and explored the underlying mechanism. We developed multidrug-resistant Caco-2 (MDR-Caco-2) cells by exposure of Caco-2 cells to increasing concentrations of doxorubicin. We identified overexpression of COX-2 and MDR-1 genes as well as activation of the NF-κB signal pathway in MDR-Caco-2 cells. Importantly, we found that sinomenine enhances the sensitivity of MDR-Caco-2 cells towards doxorubicin by downregulating MDR-1 and COX-2 expression through inhibition of the NF-κB signaling pathway. These findings provide a new potential strategy for the reversal of P-gp-mediated anticancer drug resistance.

The multiple facets of drug resistance: one history, different approaches

Some cancers like melanoma and pancreatic and ovarian cancers, for example, commonly display resistance to chemotherapy, and this is the major obstacle to a better prognosis of patients. Frequently, literature presents studies in monolayer cell cultures, 3D cell cultures or in vivo studies, but rarely the same work compares results of drug resistance in different models. Several of these works are presented in this review and show that usually cells in 3D culture are more resistant to drugs than monolayer cultured cells due to different mechanisms. Searching for new strategies to sensitize different tumors to chemotherapy, many methods have been studied to understand the mechanisms whereby cancer cells acquire drug resistance. These methods have been strongly advanced along the years and therapies using different drugs have been increasingly proposed to induce cell death in resistant cells of different cancers. Recently, cancer stem cells (CSCs) have been extensively studied because they would be the only cells capable of sustaining tumorigenesis. It is believed that the resistance of CSCs to currently used chemotherapeutics is a major contributing factor in cancer recurrence and later metastasis development. This review aims to appraise the experimental progress in the study of acquired drug resistance of cancer cells in different models as well as to understand the role of CSCs as the major contributing factor in cancer recurrence and metastasis development, describing how CSCs can be identified and isolated.

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.

Screening of feature genes of the ovarian cancer epithelia with DNA microarray

Objective

We aimed to screen differentially expressed genes (DEGs) of ovarian surface epithelia in order to provide beneficial help for early diagnosis and treatment of ovarian cancer with DNA microarrays.

Methods

We extracted the microarray expression profile GSE14407 from Gene Expression Omnibus database which conducted gene expression profiling analysis of 12 ovarian surface epithelia (OSE) and 12 laser capture microdissected serous ovarian cancer epithelia (CEPI) samples. The DEGs between OSE and CEPI were identified by Limma package of R language. Cluster analysis was employed to compare the differences of gene expression patterns between OSE and CEPI. Furthermore, DEGs were analyzed with Functional classification tool, GenMAPP software and GENECODIS.

Results

We identified 1229 DEGs including 592 down-regulated genes and 637 up-regulated genes. Pathway analysis showed that cell cycle was the most significant pathway and the DEGs related with cell cycle were almost up-regulated. Module mining analysis showed that the up-regulated DEGs were related with signal transduction while the down-regulated DEGs were related with lipid metabolism pathway and cytoskeletal structure.

Conclusion

The genes related with cell cycle, lipid metabolism and cytoskeletal structure may be the treatment targets for ovarian cancer.