Effect of histone deacetylase inhibitors on cell apoptosis and expression of the tumor suppressor genes RUNX3 and ARHI in ovarian tumors

Human epithelial ovarian cancer cells expressing CD105, CD44 and CD106 surface markers exhibit increased invasive capacity and drug resistance

The high rate of mortality associated with ovarian cancer (OC) is due in part to the development of resistance to chemotherapy, which allows the resistant tumour cells to invade and metastasise. Clarifying the mechanistic basis for drug resistance may reveal novel avenues for treatment. The present study investigated the mechanism of paclitaxel (PTX) resistance in human epithelial OC by evaluating the expression of stem cell-associated cell surface markers endoglin (CD105), CD44 antigen and vascular cell adhesion molecule 1 (CD106), in association with the malignant potential of the human OC OVCAR3 cell line and its PTX-resistant derivative OC3/TAX300. The expression of CD105, CD44 and CD106 was detected by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and flow cytometry, and cell invasion was evaluated using a Transwell invasion assay. CD105, CD44 and CD106 levels were increased in OC3/TAX300 cells compared with the OVCAR3 cells, as determined by flow cytometry (P<0.01) and RT-qPCR (P<0.05). Additionally, the number of invading cells was increased in the OC3/TAX300 group compared with the OVCAR3 group (54.7±6.65 vs. 31.8±6.55; P<0.01). A western blot analysis of cell surface marker expression in 80 clinical epithelial OC tissue samples, differing in terms of sensitivity to drug treatments, disease stage and degree of differentiation, revealed that high CD105, CD44 or CD106 expression was associated with drug resistance, advanced disease stage, poor differentiation and high rate of recurrence. These data indicated that exposure to high doses of PTX enhanced the stem-like properties of OC cells, which are associated with drug resistance and invasion and lead to poor prognosis due to induced chemoresistance and/or metastasis. Therefore, CD105, CD44 and CD106 may serve as potential stem cell-associated cell surface and prognostic markers, and therapeutic targets, in OC.

S-phase cell cycle arrest, apoptosis, and molecular mechanisms of aplasia ras homolog member I-induced human ovarian cancer SKOV3 cell lines

Objective

Aplasia Ras homolog member I (ARHI) is associated with human ovarian cancer (HOC) growth and proliferation; however, the mechanisms are unclear. The purpose of this study was to investigate ARHI effects in HOC SKOV3 cells.

Methods

We transfected SKOV3 cells with PIRES2-EGFP-ARHI and measured growth inhibition rates, cell cycle distribution, apoptosis rates, and expression of P-STAT3 (phosphorylated signal transduction and activators of transcription 3) and P-ERK (phosphorylated extracellular signal regulated protein kinase).

Results

Our data showed significant inhibition of growth, significantly increased S-phase arrest and apoptosis rates, and reduction of P-STAT3 and P-ERK1/2 expression levels.

Conclusions

We propose the mechanism may involve ARHI-induced phosphorylation of ERK1/2 and STAT3 protein kinases, thereby blocking proliferation signaling pathways, to induce HOC SKOV3 apoptosis.

hMSH2 expression is associated with paclitaxel resistance in ovarian carcinoma, and inhibition of hMSH2 expression in vitro restores paclitaxel sensitivity

The objective of the present study was to investigate the association between paclitaxel resistance, gene copy number, and gene expression in ovarian carcinoma, and to restore paclitaxel sensitivity in a paclitaxel-resistant ovarian carcinoma cell line by using hMSH2-targeting siRNA. Paclitaxel-resistant ovarian carcinoma cell lines OC3/TAX300 and OC3/TAX50 and their parental cell lines were analyzed by comparative genomic hybridization, and the expression levels of hMSH2 in ovarian carcinoma cell lines and tissues were determined. An siRNA targeted to hMSH2 mRNA was used to transfect a paclitaxel-resistant cell line. We assessed the morphological features, proliferation, and susceptibility to apoptosis of the transfected cells after paclitaxel treatment. Chromosome 2p21 (gene locus of hMSH2) was amplified in OC3/TAX300 cells. hMSH2 was overexpressed in 93.9 and 47.6% of paclitaxel-treated and untreated ovarian carcinoma tissue samples (P=0.0001), respectively. hMSH2 was overexpressed in 93.3 and 54.2% of low-differentiated and moderate-to-highly differentiated ovarian carcinoma tissue samples (P=0.0008), respectively. hMSH2 expression was inhibited in the OC3/TAX300 cells transfected with hMSH2 siRNA. hMSH2 siRNA increased paclitaxel sensitivity, inhibited OC3/TAX300 cell proliferation (G2/M arrest), and increased susceptibility to apoptosis. hMSH2 expression was upregulated in ovarian carcinoma cell lines and tissues after paclitaxel treatment. hMSH2 overexpression is related to paclitaxel resistance and poor prognosis. Inhibition of hMSH2 expression in vitro restores paclitaxel sensitivity in paclitaxel‑resistant ovarian carcinoma cell lines and indicates a new direction in adjuvant therapy for ovarian carcinoma.