ABSTRACT
Objective:To investigate the mechanism of endoplasmic reticulum (ER) stress-induced chemoresistance to cisplatin in gastric cancer cells. Methods:ER stress models were established in both BGC823 and SGC7901 gastric cancer cells. The expression of GRP78, an ER stress marker, was examined by Western blot analysis. Moreover, whether ER stress can decrease the sensitivity of gastric cancer cells to cisplatin and activate P38 was explored by flow cytometry and Western blot analysis, respectively. Whether ER stress-induced chemoresistance to cisplatin can be abrogated by blocking P38 activity in gastric cancer was also elucidated using flow cytometry. Results:GRP78 protein expression markedly increased after treating BGC823 and SGC7901 gastric cancer cells with tunica-mycin (TM) or thapsigargin (TG) for 8, 16, and 24 h (P0.05). Both P38 inhibitors, either SB203580 or PD169316, can inhibit the activation of P38. The inhibition of P38 activity can overcome ER stress-induced chemoresistance to cisplatin in gastric cancer cells (P<0.05). Con-clusion:ER stress can trigger the chemoresistance to cisplatin by activating P38 in gastric cancer cells.
ABSTRACT
AIM: To clone and express mouse canstatin (m canstatin)cDNA and provide a basis for the further research on its anti-angiogenic activity and potential application for cancer therapy. METHODS: Total RNA was extracted from mouse liver tissue by Trizol Reagent, and mouse canstatin cDNA was amplified by RT- PCR, then cloned into vector pMD18-T for sequencing. pET30a(+)-m canstatin recombinant plasmid was constructed and expressed in E.coli BL21 with induction of IPTG. RESULTS: Mouse canstatin cDNA is 684 bp coding 227 amino acids. The sequences of both cDNA and amino acid share high homology with human canstatin, with cDNA identity at 89% and amino acids identity at 96% to human canstatin. In the present study, pET30a(+)-m canstatin recombinant plasmid was expressed in E.coli BL21. CONCLUSION: Mouse canstatin cDNA has been cloned for the first time. Constructed pET30a(+)-m canstatin recombinant plasmid is highly expressed in E.coli BL21.