Two-dimensional database of a Burkitt lymphoma cell line (DG 75) proteins: protein pattern changes following treatment with 5'-azycytidine

Effects of 5-azacytidine on the growth inhibition of human hepatocellular carcinoma cells and reversion of p16 hympermethylation

AIM: To investigate correlation between DNA methylation alteration and hepatocellular carcinoma as well as to explore mechanisms of 5-aza-CR inhibiting hepatoma cell lines and reversed methylation.

METHODS: Human hepatoma cell lines, HuH-7, and the murine xenograft model were treated with 5-aza-CR. Cell morphology changes were determined under phase contrast microscopy, cell growth speed was measured using MTT assay, cell cycle distribution and apoptosis rate were estimated using flow cytometry, methylation status of p16 was determined using methylation-specific PCR and mRNA expression of p16 was determined using RT-PCR.

RESULTS: After treatment with 5-aza-CR, significant inhibiting effects were detected both in hepatoma cell lines HuH-7 and the murine xenograft model cells. In the treatment group, G₁ of HuH-7 increased by 41.1% ± 3.2%, S and G₂ + M decreased by 39.0% ± 1.4% and 2.2% ± 0.7%, respectively, and apoptosis rate increased by 30.0% ± 4.5%. In the murine xenograft model group, G₁ increased by 27.4% ± 3.1%, S and G₂ + M decreased by 25.8% ± 2.1% and 1.6% ± 1.8%, respectively, and apoptosis rate increased by 2.9% ± 0.6%. Only methylating PCR product appeared before treatment with drugs, Conversely while only demethylating PCR amplification product was detected after drug treatment. For the murine xenograft model group, methylated PCR product was detected in the control group, however, methylated and demethylated PCR amplification products were observed in the experimental group. Both cell and xenografted nude mice presented the expression of p16 mRNA in experimental group. No expression of p16 mRNA was detected in the control group.

CONCLUSION: 5-aza-CR inhibits tumor cell growth, decreases cell cycle and increases mRNA expression of p16 in hepatoma cell lines both in vitro and in vivo. 5-aza-CR inhibits the malignant phenotypes of human hepatocellular carcinoma cells and reverses hympermethylation of p16.