Role of Δ133p53 in Tumor Necrosis Factor-induced survival of p53 functions in MKN45 gastric cancer cell line

Z.-M. Shang, J.-D. Tang, Q.-Q. Jiang, A. Guo, N. Zhang, Z.-X. Gao, W.-S. Ji

Department of Oncology, People’s Hospital of Weifang Traditional Chinese Medicine,Weifang, P.R. China. ljcwfyxy@126.com

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• Oncology

OBJECTIVE: To explore the role of Δ133p53 in the effect of recombinant mutant human Tumor Necrosis Factor (rmhTNF) on two gastric cancer cell lines.

MATERIALS AND METHODS: MKN45 (with Δ133p53 expression) or SGC7901 (without Δ133p53 expression) cells were treated with rmhTNF of different concentrations only or combined with fluorouracil (5-FU), and the growth inhibition rate was detected by a cell counting kit, and apoptosis by flow cytometry. The mRNA of Δ133p53, p53, Gadd45α, MDM2, PTEN and Bax was measured by reverse transcription PCR (RT-PCR) or Nested PCR (nPCR).

RESULTS: On Δ133p53-positive MKN-45 cells, the effect of rmhTNF was significant in growth inhibition test (t = –9.558, p < 0.01); also, the effect of 5-FU was improved by rmhTNF with remarkable time- and dose-effect (F = 82.742, p < 0.01; F = 128.583, p < 0.01). However, on Δ133p53-negative SGC-7901 cells, no growth inhibition was showed by rmhTNF only (t = –0.121, p > 0.05). In apoptosis test, the effect of rmhTNF was significant on MKN45 cells, and the effect of 5-FU was improved significantly by rmhTNF (F = 123.931, p < 0.05). In mRNA measurement, rmhTNF-induced up-regulation of p53 accompanied with down-regulation of Δ133p53, which correlated significantly to the change of p53 downstream molecules, including MDM2, PTEN, Gadd45α, and Bax.

CONCLUSIONS: The results in these experiments suggested that Δ133p53 play a pivotal role in rmhTNF-induced survival of p53 functions in Δ133p53-positive MKN-45 cells.

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