Effect of p53β on human gastric cancer cells treated with recombinant mutated human TNF and cisplatin.

The present study aimed to investigate the role of tumour protein 53 isoform b (p53 beta) on human gastric cancer (GC) cell lines treated with recombinant mutated human tumour necrosis factor (rmhTNF) and cisplatin. The Cell Counting Kit-8 assay was used to assess growth in the GC cell lines MKN45 and SGC7901, following treatment with rmhTNF in the presence or absence of cisplatin. Levels of p53 beta and bcl-2 apoptosis regulator (bcl-2) mRNA were assessed using reverse transcription-polymerase chain reaction. The results demonstrated that growth was significantly inhibited by either cisplatin or rmhTNF treatments alone in MKN45 cells, and combination treatment with cisplatin and rmhTNF had a synergistic effect on growth inhibition of MKN45 cells. Notably, these observations were not evident in SGC7901 cells, where a mutant form of p53 is present. Treatment of MKN45 cells with rmhTNF did not affect bcl-2 or p53 beta mRNA expression levels. However, treatment of MKN45 cells with cisplatin induced upregulation of p53 beta and downregulation of bcl-2 mRNA expression levels, and these effects were enhanced by combination treatment with rmhTNF. Pearson correlation analysis revealed a negative correlation between the expression of p53 beta and bcl-2 mRNA, and a negative correlation between bcl-2 mRNA expression and the inhibition of cell growth. In conclusion, the inhibitory effect of cisplatin on the growth of MKN45 GC cells was enhanced by rmhTNF via unknown mechanisms that involved p53 beta, indicating that p53 beta may be an appropriate therapeutic target for the treatment of GC.