Background and purpose:Δ133p53 can promote tumor cell growth, but the exact mechanism is not clear. This study was aimed to observe the expression and signiifcant of the p53 isoformsΔ133p53 and p53 gene downstream molecules MDM2 and cyclin G1 genes by 5-FU-MKN45 gastric cancer cell line model. Methods:Af-ter using different concentrations of 5-FU (50μg/mL, 100μg/mL) to human gastric cancer cell line MKN45, inhibition rate should be detected by MTT assay, the changes ofΔ133p53 mRNA, MDM2 mRNA and cyclin G1 mRNA express-ing were detected by reverse transcription-polymerase chain reaction (RT-PCR). Differences between these groups were analyzed by ANOVA, comparisons within groups were analyzed by t-test, bivariate correlation was analyzed by Pearson linear correlation. Results:MTT results showed that with the increased concentration of 5-FU and the extension of time, the cell inhibition rates increased gradually. The inhibition rates of 50μg/mL 5-FU were 41.10%, 54.79%and 68.48%, for culturing 24, 48 and 72 hours. There were statistically signiifcant differences between the groups(F=45.52, P=0.00). The inhibition rates of 100μg/mL 5-FU were 69.53%, 78.21%and 86.92%, for culturing 24, 48 and 72 hours. There were statistically signiifcant differences between the groups(F=85.58,P=0.00). The inhibition rates of 50 and 100μg/mL were 41.10%and 69.53%, for culturing 24 hours. There were statistically signiifcant differences between the groups(F=51.29, P=0.00). The inhibition rates of 50 and 100μg/mL were 54.79%and 78.21%, for culturing 48 hours. There were statistically signiifcant differences between the groups(F=51.29, P=0.00). The inhibition rates of 50 and 100μg/mL were 68.48%and 86.82%, for culturing 72 hours. There were statistically signiifcant differences between the groups(104.91, P=0.00). RT-PCR results showed that with the increase of the concentration of 5-FU, theΔ133p53 mRNA, MDM2 mRNA and cyclin G1 mRNA expression gradually declined in gastric cancer cell line MKN45 cells, and there were statistically signiifcant differences between the groups(F=738.532, 1 396.607, 2 785.56,P=0.00). Cor-relation analysis showed that the expressions ofΔ133p53 mRNA and MDM2 mRNA in gastric cancer were positively correlated (r=0.871, P=0.01), while the expression of cyclin G1 mRNA and p53 mRNA had no obvious relevance (P=0.13). Conclusion:In the 5-FU-MKN45 gastric cancer cell line model, anti-tumor pathway ofΔ133p53 isomers is related with MDM2 but was not related with cyclin G1.

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.