ECRG2 enhances the anti-cancer effects of cisplatin in cisplatin-resistant esophageal cancer cells via upregulation of p53 and downregulation of PNCA

AIM To explore the anti-tumor effects of esophageal cancerrelated gene 2(ECRG2) in combination with cisplatin(DDP) in DDP-resistant esophageal cancer cells(EC9706/DDP).METHODS A drug-resistant cell model was established, with EC9706/DDP cells being treated with ECRG2 and/or DDP. Cell viability was examined by MTT assay. The rate of cell apoptosis was determined by flow cytometry. The mR NA expression levels of proliferating cell nuclear antigen(PCNA), metallothionein(MT), and p53 were determined by RT-PCR and PCNA, while MT and p53 protein expression levels were determined by western blotting.RESULTS The anti-proliferative effect of ECRG2 in combination with DDP was superior when compared to ECRG2 or DDP alone. The inhibition rate for the combination reached its peak(51.33%) at 96 h. The early apoptotic rates of the control, ECRG2 alone, DDP alone, and ECRG2 plus DDP groups were 5.71% ± 0.27%, 12.68% ± 0.61%, 14.15% ± 0.87%, and 27.96% ±0.36%, respectively. Although all treatment groups were significantly different from the control group(P < 0.05), the combination treatment of ECRG2 plus DDP performed significantly better when compared to either ECRG2 or DDP alone(P < 0.05). The combination of ECRG2 and DDP significantly upregulated p53 m RNA and protein levels and downregulated PCNA m RNA and protein levels compared to ECRG2 or DDP alone(P < 0.05). However, no changes were seen in the expression of MT mR NA or protein.CONCLUSION ECRG2 in combination with DDP can inhibit viability and induce apoptosis in esophageal cancer DDP-resistant cells, possibly via upregulation of p53 expression and downregulation of PCNA expression. These findings suggest that the combination of ECRG2 and DDP may be a promising strategy for the clinical treatment of esophageal cancers that are resistant to DDP.

Role of MetallothioneinlH in Cisplatin Resistance of Non-Small Cell Lung Cancer Cells

Objective： Despite platinum-based adjuvant chemotherapy has improved greatly patients＇ outcomes, drug resistance poses a major impediment to the successful use of such an effective agent. Metallothioneins（MTs） are known to play putative roles in cancer cell proliferation, apoptosis, differentiation, drug resistance and prognosis. The present studiy was to investigte the role of metallethioeinlH（MTIH） in cisplatin resistance of human non-small cell lung cancer（NSCLC） cell lines in vitro or its possible molecular mechanisms. Methods： MTIH mRNA expression in A549 and A549/DDP cells was detected by RT-PCR. A recombinant eukaryotic expression plasmid pcDNA3.1（-）-MT1H was constructed and transfected into A549 cells which express no MTIH. MT1H siRNA was transfected into A549/DDP cells which express MTIH highly. MTIH expression was detected by RT-PCR and Immunoblot. The chemosensitivity to cisplatin was assessed by MTT assay. Apoptosis rate was determined by Tunel and FCM. Bcl-2 and Bax were determined by immunohistochemistry. Results： MT1H mRNA was expressed in A549/DDP but not in A549. After transfection of MT1H, MT1H expression was enhanced and the chemosensitivity to cisplatin was decreased in A549 cells. Inversely, after transfection of MT1H siRNA, MT1H expression was decreased and the chemosensitivity to cisplatin was increased in A549/DDP. The apoptosis rate induced by cisplatin was increased and Bcl-2 was down-regulated but Bax showed little change in A549/DDP cells interferred with MT1H siRNA. Conclusion： MT1H overexpression can promote drug resistance in A549 cells . Down-regulation of MTIH interfered with siRNA can effectively reverses the drug resistance in A549/DDP cells by down-regulating the expression of Bcl-2 and increasing cisplatin induced apoptosis. SiRNA targeting MT1H combined with chemotherapy may be a very promising strategy for treatment of lung cancer.