Phase II study of epirubicin plus oxaliplatin and infusional 5-fluorouracil as first-line combination therapy in patients with metastatic or advanced gastric cancer

Anti-cancer and Sensibilisation Effect of Triptolide on Human Epithelial Ovarian Cancer

Introduction: Advanced ovarian cancer is the main cause of ovarian cancer deaths, and it is important to seek safe and effective phytochemicals to suppress cancer or lower the chemotherapy resistance of ovarian cancer. Methods: This study evaluated the effect of Triptolide (TPL) on the proliferation, cycle distribution, apoptosis, and ultra-structure of COC1/DDP cells in vitro, as well as the anti-cancer effect and sensibilisation effect of TPL in vivo. Results: The results indicated that TPL could significantly inhibit the growth of COC1/DDP cells (P<0.05), and 3 ng/ml TPL and 50 ng/ml TPL made COC1/DDP cells present obvious apoptosis characteristics and arrest 35% and 55% of COC/DDP cells in the G0/G1 phase, respectively (P<0.05). The animal experiments also indicated that 0.1mg/kg.d TPL significantly reduced the tumour weight and the spleen cell transformation rate (SI), and it lowered the inflammatory factors IL-2 and TNF-a in rat serum (P<0.05). Moreover, the significant reduction of p-Akt and p-GSK3β made the TPL+DDP possess the highest apoptosis rate [(51.13±3.325)%] in COC1/DDP cells. Conclusions: TPL used in combination with DDP may produce a synergistic anti-cancer effect that warrants further investigation for its potential clinical applications in the treatment of epithelial ovarian cancer.

MicroRNA‑197 reverses the drug resistance of fluorouracil‑induced SGC7901 cells by targeting mitogen‑activated protein kinase 1

MicroRNAs (miRNAs) are a group of small non‑coding RNA molecules, which serve an important function in the development of multidrug resistance in cancer through the post‑transcriptional regulation of gene expression and RNA silencing. In the present study, the functional effects of miR‑197 were analyzed in chemo‑resistant gastric cancer cells. Low expression levels of miR‑197 were observed in the fluorouracil (5‑FU)‑resistant gastric cell line SGC7901/5‑FU when compared with those in the parental gastric cell line SGC7901. Overexpression of miR‑197 in SGC7901/5‑FU cells was identified to partially restore 5‑FU sensitivity. miRNA target prediction algorithms suggested that mitogen‑activated protein kinase 1 (MAPK1) is a candidate target gene for miR‑197. A luciferase reporter assay confirmed that miR‑197 led to silencing of the MAPK1 gene by recognizing and then specifically binding to the predicted site of the MAPK1 mRNA 3'‑untranslated region. When miR‑197 was overexpressed in SGC7901 cells, the protein levels of MAPK1 were downregulated. Furthermore, MAPK1 knockdown significantly increased the growth inhibition rate of the SGC7901/5‑FU cells compared with those in the control group. These results indicated that miR‑197 may influence the sensitivity of 5‑FU treatment in a gastric cancer cell line by targeting MAPK1.

miR-106a confers cisplatin resistance by regulating PTEN/Akt pathway in gastric cancer cells

Recent studies have shown that microRNA-106a (miR-106a) is overexpressed in gastric cancer and contributes to tumor growth. In this study, we investigated whether miR-106a mediated resistance of the gastric cancer cell line SGC7901 to the chemotherapeutic agent cisplatin (DDP). MiR-106a expression was up-regulated in the DDP resistant cell line SGC7901/DDP compared with its parental line SGC7901. Transfection of miR-106a induced DDP resistance in SGC7901, while suppression of miR-106a in SGC7901/DDP led to enhanced DDP cytotoxicity. Further study indicated that the mechanism of miR-106a-induced DDP resistance involved the expression of phosphatase and tensin homolog deleted from chromosome 10 (PTEN) protein and its downstream phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT) pathway. This study provides a novel mechanism of DDP resistance in gastric cancer.

Identification of GAS1 as an epirubicin resistance-related gene in human gastric cancer cells with a partially randomized small interfering RNA library

Epirubicin has been widely used for chemotherapeutic treatment of gastric cancer; however, intrinsic and acquired chemoresistance remains an obstacle to successful management. The mechanisms underlying epirubicin resistance are still not well defined. Here we report the construction and application of a partially randomized retrovirus library of 4 x 10(6) small interfering RNAs to identify novel genes whose suppression confers epirubicin resistance in gastric cancer cells SGC7901. From 12 resistant cell colonies, two small interfering RNAs targeting GAS1 (growth arrest-specific 1) and PTEN (phosphatase and tensin homolog), respectively, were identified and validated. We identified a previously unrecognized chemoresistance role for GAS1. GAS1 suppression resulted in significant epirubicin resistance and cross-resistance to 5-fluorouracil and cisplatin in various gastric cancer cell lines. GAS1 suppression promoted multidrug resistance through apoptosis inhibition, partially by up-regulating the Bcl-2/Bax ratio that was abolished by Bcl-2 inhibition. GAS1 suppression induced chemoresistance partially by increasing drug efflux in an ATP-binding cassette transporter and drug-dependent manner. P-glycoprotein (P-gp) and BCRP (breast cancer resistance protein) but not MRP-1 were up-regulated, and targeted knockdown of P-gp and BCRP could partially reverse GAS1 suppression-induced epirubicin resistance. Verapamil, a P-gp inhibitor, could reverse P-gp substrate (epirubicin) but not non-P-gp substrate (5-fluorouracil and cisplatin) resistance in GAS1-suppressed gastric cancer cells. BCRP down-regulation could partially reverse 5-fluorouracil but not cisplatin resistance induced by GAS1 suppression, suggesting 5-fluorouracil but not cisplatin was a BCRP substrate. These results suggest that GAS1 might be a target to overcome multidrug resistance and provide a novel approach to identifying candidate genes that suppress chemoresistance of gastric cancers.

Inhibition of PI3K increases oxaliplatin sensitivity in cholangiocarcinoma cells

BACKGROUND

Resistance of cholangiocarcinoma to chemotherapy is a major problem in cancer treatment. The mechanism of resistance is believed to involve phosphoinositide-3- kinase (PI3K)/Akt activation. Although the platinum-containing compound oxaliplatin has been extensively used in the treatment of several solid tumors, recent data regarding its use to treat cholangiocarcinoma are ambiguous. Oxaliplatin resistance in this disease could potentially involve PI3K pathways. We, therefore, examined the effects of PI3K pathways in cholangiocarcinoma cells in modulating oxaliplatin resistance.

RESULTS

After exposing the cholangiocarcinoma cell lines RMCCA1 and KKU100 to oxaliplatin, the levels of Akt and mTOR phosphorylation increased, as shown by western blot analysis. The WST-1 cell proliferation assay showed increased inhibition of cell growth under high concentrations of oxaliplatin. The combination of oxaliplatin with LY294002, an inhibitor of PI3K, resulted in a remarkable arrest of cell proliferation. Deactivation of mTOR by RAD001 was also synergistic with oxaliplatin, although to a lesser extent. The combination of oxaliplatin and a PI3K inhibitor also resulted in a significant induction of apoptosis, as demonstrated by the TUNEL assay.

CONCLUSION

Activation of PI3K might protect cholangiocarcinoma cells from oxaliplatininduced cytotoxicity. Although the inhibition of PI3K and the inhibition of mTOR both enhance oxaliplatin-induced cytotoxicity, PI3K inhibition has a greater effect. Targeting the PI3K pathway may be a useful approach to improve the chemotherapeutic sensitivity of cholangiocarcinoma.