AIM To investigate the role of Delta 133p53 isoform in nuclear factor-kappa B (NF-kappa B) inhibitor pyrrolidine dithiocarbamate (PDTC)-mediated growth inhibition of MKN45 gastric cancer cells. METHODS The growth rate of MKN45 cells after treatment with different concentrations of only PDTC or PTDC in combination with cisplatin was detected by the CCK-8 assay. mRNA expression levels of Delta 133p53, p53 beta, and the NF-kappa B p65 subunit and p65 protein levels were detected by reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence, respectively. Growth of MKN45 cells was significantly inhibited by PDTC alone in a dose-dependent manner (P < 0.01). Moreover, the inhibitory effect of cisplatin was remarkably enhanced in a dose- dependent manner by co-treatment with PDTC (P < 0.01). RESULTS RT-PCR analysis revealed that mRNA expression of p65 was curbed significantly in a dose-dependent manner by treatment with only PDTC (P < 0.01), and this suppressive effect was further enhanced when co-treated with cisplatin (P < 0.01). With respect to the other p53 isoforms, mRNA level of Delta 133p53 was significantly reduced in a dose-dependent manner by treatment with only PDTC or PTDC in combination with cisplatin (P0.05). A similar tendency of change in p65 protein expression, as observed for the corresponding mRNA, was detected by immunofluorescence analysis (P0.01). CONCLUSION Delta 133p53 isoform (not p53 beta) is required in PDTC-induced inhibition of MKN45 gastric cancer cells, indicating that disturbance in the cross-talk between p53 and NF-kappa B pathways is a promising target in pharmaceutical research for the development of treatment strategies for gastric cancer.