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Background and purpose: Little about the function of p53 isoforms in gastric cancer was reported. This study was designed to explore the role ofΔ133p53 in the effect of recombinant mutant human tumor necrosis factor (rmhTNF) on gastric cancer cells, and provide a new basis for the diagnostics and therapeutics of gastric carcinoma. Methods: MKN45 (withΔ133p53 expression) or SGC7901 (withoutΔ133p53 expression) cells were treated with rmhTNF of different concentrations only or combined with 5-FU (a traditional gastric cancer cellular killer), and the growth inhibition rate and apoptosis was detected by CCK-8 and lfow cytometry. mRNA expressions ofΔ133p53, Gadd45αand CyclinB1 were measured by nested reverse transcription-polymerase chain reaction (nRT-PCR) or real-time polymerase chain reaction(RT-PCR). Results:On MKN-45 cells with positiveΔ133p53 expression, the inhibitory effect of rmhTNF was signiifcant, the inhibition rates of 50 and 500 IU/mL rmhTNF were 24.82%, 72.33%after culturing for 24 h (t=-9.558, P<0.01);also, the inhibitory effect of 5-FU was improved by rmhTNF remarkably in time-and dose-dependence, the inhibition rates of 5-FU (25 μg/mL), rmhTNF (50 IU/mL) combined with 5-FU (25 μg/mL), rmhTNF (500 IU/mL) combined with 5-FU (25 μg/mL) were 18.20%, 48.66%, 59.83%, separately, after culturing for 24 h (F=82.742, P<0.01);the inhibition rates of rmhTNF (50 IU/mL) combined with 5-FU (25 μg/mL) were 48.66%, 68.20%, 85.23%, separately, after culturing for 24 h, 48 h and 72 h (F=128.583, P<0.01). However, on SGC-7901 cells with negativeΔ133p53 expression, no growth inhibition was showed by rmhTNF only, the inhibition rates of 50 and 500 IU/mL were 2.74%, 3.25%after culturing for 24 h (t=-0.121, P>0.05). In apoptosis test, the apopto-sis-enhancing effect of rmhTNF was signiifcant on MKN45 cells, and the apoptosis-enhancing effect of 5-FU was fur-ther promoted signiifcantly by rmhTNF, the apoptosis of rmhTNF (50 IU/mL), rmhTNF (50 IU/mL) combined with 5-FU (25 μg/mL), rmhTNF (500 IU/mL) combined with 5-FU (25 μg/mL) were 18.20%, 48.66%, 59.83%, separately, after culturing for 24 h (F=123.931, P<0.05). In mRNA measurement, down-regulation ofΔ133p53 and CyclinB1, up-regula-tion of Gadd45αwere signiifcant in MKN45 cells treated by rmhTNF alone or combined with 5-FU. In nRT-PCR anal-ysis, the mRNA levels ofΔ133p53 were relatively 0.886, 0.499, 0.330, 0.161 (F=240.927, P<0.01);In real-time PCR analysis, the mRNA levels of Gadd45αwere 1.227, 1.694, 3.394, and the mRNA levels of CyclinB1 were 1.221, 0.722, 0.316, relatively. The expression ofΔ133p53 was positively related to CyclinB1 (r=0.977, P<0.01), but negatively re-lated to Gadd45α(r=-0.950, P<0.01). Conclusion:InΔ133p53 positively expressed MKN45 cells, rmhTNF showed as an effective tumor inhibitor and an enhancer of 5-FU as well, and this effect might be helped by two p53 down-stream molecules CyclinB1 and Gadd45α. The results suggest thatΔ133p53 might be a key target for the biological effect of rmhTNF against gastric cancer.