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Purpose: RUNX3 (PEBP2aC/CBFA3/AML2) recently cloned a candidate tumor suppressor gene. Studies have shown that the abnormal gene methylation in many human tumors, and liver cancer in the expression of the gene is still in the exploratory stage. This study was demethylating agent 5 - aza-2'-deoxycytidine (5-Aza-2'-deoxycytidine ,5-Aza-CdR) induced human hepatoma cell line HepG2 hypermethylation inactivation of RUNX3 gene expression and the biological behavior of the tumor cells and drug sensitivity. Methods: The expression of RUNX3 gene hepatoma cell line HepG2 target cells, divided into without any treatment group and 5-Aza-CdR treated. By reverse transcription - polymerase chain reaction (RT-PCR) assay tumor suppressor gene RUNX3 mRNA expression levels of change: observed by MTT colorimetric cell growth activity and the chemotherapy drug 5 - fluorouracil (5-fluorouracil, 5-FU) 50 values ??and doxorubicin (adriamycin, ADM) IC; plate colony assay sensitivity of the cells to 5 - fluorouracil (5-fluorouracil ,5-FU); flow cytometry (FCM ) to determine the cell cycle and doxorubicin (adriamycin, ADM) accumulation rate; the TEM observations apoptosis morphological changes. Results: The control group HepG2 cells could not be detected the RUNX3 gene mRNA expression, while after the treatment 0.1,5.0 μmol/L5-Aza-CdR, RUNX3 mRNA seen re-expression. 5-Aza-CdR may be time, concentration-dependently inhibited the proliferation of HepG2 cells (P <0.05), the correlation coefficient (γ) were γ24h = 0.894, γ48h = 0.973 γ72h = 0.967,24,48 and 72 h IC < sub> 50 were 87.5,84.7, and 59.0μmol / L. After 5-Aza-CdR treatment, electron microscopy showed that HepG2 cells as early apoptotic morphological changes. Were used for the 5.0 and 10.0gmol / L concentration of 5-Aza-CdR treatment HepG2 cells 72 h compared with the control group, the S-phase cells increased, decrease in G 1 phase cells, suggesting that cells S phase arrest occurred. MTT assay 5-Aza-CdR cells treated with 5-FU and doxorubicin IC 50 is significantly lower than the control group (P <0.05), the former intracellular doxorubicin fluorescence intensity was significantly doxorubicin accumulated within the cell rate is higher than the latter (P <0.05), i.e.. Conclusion: The demethylation preparation of 5-Aza-CdR can effectively activate hepatoma cell line HepG2 due to hypermethylation of RUNX3 gene silencing re transcriptional induction of the expression of the gene, thus inhibiting the growth of tumor cells, it increased apoptosis, hepatoma cells and enhanced sensitivity to chemotherapeutic drugs.
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