Abstract
Objective: The present study employed 5-aza-2’-deoxycytidine (5-Aza-CdR) to treat non-small cell lung cancer(NSCLC) cell line A549 to investigate the effects on proliferation and expression of the TFPI-2 gene.
Methods:Proliferation was assessed by MTT assay after A549 cells were treated with 0, 1, 5, 10 μmol/L 5-Aza-CdR, a specificdemethylating agent, for 24 ,48 and 72h. At the last time point cells were also analyzed by flow cytometry (FCM)to identify any change in their cell cycle profiles. Methylation-specific polymerase chain reaction (MSPCR), realtime polymerase chain reaction(real-time PCR) and western blotting were carried out to determine TFPI-2 genemethylation status, mRNA expression and protein expression.
Results: MTT assay showed that the growth ofA549 cells which were treated with 5-Aza-CdR was significantly suppressed as compared with the control group(0 μmol/L 5-Aza-CdR). After treatment with 0, 1, 5, 10 μmol/L 5-Aza-CdR for 72h, FCM showed their proportionin G0/G1 was 69.7±0.99%, 76.1±0.83%, 83.8±0.35%, 95.5±0.55% respectively (P<0.05), and the proportion in Swas 29.8±0.43%, 23.7±0.96%, 15.7±0.75%, 1.73±0.45%, respectively (P<0.05), suggesting 5-Aza-CdR treatmentinduced G0/G1 phase arrest. MSPCR showed that hypermethylation in the promoter region of TFPI-2 genewas detected in control group (0 μmol/L 5-Aza-CdR), and demethylation appeared after treatment with 1, 5,10 μmol/L 5-Aza-CdR for 72h. Real-time PCR showed that the expression levels of TFPI-2 gene mRNA were1±0, 1.49±0.14, 1.86±0.09 and 5.80±0.15 (P<0.05) respectively. Western blotting analysis showed the relativeexpression levels of TFPI-2 protein were 0.12±0.01, 0.23±0.02, 0.31±0.02, 0.62±0.03 (P<0.05). TFPI-2 proteinexpression in A549 cells was gradually increased significantly with increase in the 5-Aza-CdR concentration.
Conclusions: TFPI-2 gene promoter methylation results in the loss of TFPI-2 mRNA and protein expressionin the non-small cell lung cancer cell line A549, and 5-Aza-CdR treatment could induce the demethylation ofTFPI-2 gene promoter and restore TFPI-2 gene expression. These findings provide theoretic evidence for clinicaltreatment of advanced non-small cell lung cancer with the demethylation agent 5-Aza-CdR. TFPI-2 may be onemolecular marker for effective treatment of advanced non-small cell lung cancer with 5-Aza-CdR.
Keywords
)