Tissue factor pathway inhibitor-2 (TFPI-2) that inhibits plasmin,trypsin and matrix metalloproteinases is a broad-spectrum inhibitor of serine proteinase.TFPI-2 can accommodate the invasion and metastasis of human non-small-cell lung cancer by maintaining the integrity of extracellular matrix and regulating the angiogenesis and apoptosis of tumor cells.It has been a new target for gene therapy of cancers.

OBJECTIVETo investigate the inhibitory effect of classic demethylating drug 5-aza-2'-deoxycytidine (5-Aza-CdR) on the growth of human lung adenocarcinoma cells in nude mouse xenograft models, and to observe its effect on methylation status and expression of TFPI-2 gene in the nude mouse xenograft tissues.

METHODSThe nude mouse xenograft model was established by subcutaneous inoculation of human lung adenocarcinoma A549 cells. According to different doses of 5-Aza-CdR, the tumor-bearing nude mice were randomly divided into experimental groups (0.5 mg/kg group, 1 mg/kg group, 2 mg/kg group) and control group (0 mg/kg group). The tumor growth in the nude mice was observed. The methylation status and the expression of TFPI-2 gene mRNA and protein were detected by methylation specific polymerase chain reaction, real-time fluorescent quantitative polymerase chain reaction and Western blot assay.

RESULTSThe nude mice were euthanized at 28 days after intraperitoneal injection of 5-Aza-CdR. The body weight of tumor-bearing nude mice was (27.12 ± 0.38) g in the 0 mg/kg group, (26.80 ± 0.18) g in the 0.5 mg/kg group, (26.67 ± 0.28) g in the 1 mg/kg group, and (26.50 ± 0.26) g in the 2 mg/kg group, showing no significant difference among them (P > 0.05). The volume of xenograft tumors in the 0 mg/kg group was (709.22 ± 2.87)mm³, (400.67 ± 2.68)mm³ in the 0.5 mg/kg group, (285.71 ± 2.91)mm³ in the 1 mg/kg group, and (230.44 ± 3.15)mm³ in the 2 mg/kg group, showing a significant difference (P < 0.05). There were complete methylation of TFPI-2 gene in the 0 mg/kg group, incomplete methylation in the 0.5 and 1 mg/kg groups, and unmethylation in the 2 mg/kg group. The relative mRNA level in the 0, 0.5, 1, 2 mg/kg groups were 1.00 ± 0.00, 1.67 ± 0.07, 3.40 ± 0.24, and 5.55 ± 0.61, respectively (P < 0.05). The relative expression level of TFPI-2 protein in the 0, 0.5, 1, 2 mg/kg groups was 0.18 ± 0.02, 0.36 ± 0.01, 0.64 ± 0.02, and 0.81 ± 0.20, respectively (P < 0.05).

CONCLUSIONS5-Aza-CdR suppresses the tumor growth of human lung adenocarcinoma cells in nude mouse xenograft models, and induces expression of TFPI-2 gene in the xenograft tumor cells. The mechanism might be that 5-Aza-CdR induces re-expression of demethylated TFPI-2 gene by demethylation, and thus inhibits the growth and proliferation of human lung adenocarcinoma cells.

Adenocarcinoma ; drug therapy ; pathology ; Animals ; Antimetabolites, Antineoplastic ; pharmacology ; Azacitidine ; analogs & derivatives ; pharmacology ; Cell Proliferation ; drug effects ; DNA Methylation ; Disease Models, Animal ; Gene Expression Regulation, Neoplastic ; Glycoproteins ; genetics ; Heterografts ; Humans ; Lung Neoplasms ; drug therapy ; pathology ; Mice ; Mice, Nude ; RNA, Messenger ; metabolism ; Random Allocation