[Expression of WW domain containing oxidoreductase gene in cholangiocarcinoma and its effect on the biological behavior of cancer cell line RBE].

OBJECTIVE

To study the effects of anti-oncogene WWOX on cell growth of cholangiocarcinoma.

METHODS

The expression of WWOX protein was detected with immunohistochemical method-SP in 54 patients with cholangiocarcinoma from July 2005 to May 2010 and 12 samples of normal bile duct tissues. The recombinant WWOX eukaryotic expression plasmid was introduced into RBE cells by liposome-mediated transfection and positive cell clones were selected and amplified. The mRNA and protein expressions in RBE cells stably transfected with WWOX were investigated by quantitative RT-PCR and Western Blot before and after transfection. Cell proliferation was tested by MTT, cell apoptosis was assessed by FCM, the alteration of mitochondria membrane potential (ΔΨm) was detected by JC-1 staining method, cell invasion was determined by Transwell chamber assay. The expression change of bcl-2, bax, FasL, caspase-3 mRNA and protein was detected by quantitative RT-PCR and Western Blot.

RESULTS

The expression of WWOX protein was significantly lower in cholangiocarcinoma than that in normal bile duct tissues and loss of WWOX protein expression was found in 40.7% of cholangiocarcinoma specimens (P < 0.05). RBE cells with stable transfection of WWOX were established. Quantitative RT-PCR showed that the expression of WWOX mRNA was significantly enhanced and Western Blot demonstrated that WWOX protein expression was markedly increased. MTT showed that WWOX gene transfection significantly decreased the proliferation of RBE cells (P < 0.05). FCM analysis showed that the apoptosis rate after transfection was significantly promoted [(1.1 ± 0.6)% vs. (1.7 ± 0.5)% vs. (35.2 ± 4.4)%, P < 0.01], JC-1 staining method indicated that the experimental group was loss of ΔΨm [(12.6 ± 1.9)% vs. (13.6 ± 1.8)% vs. (48.7 ± 2.9)%, P < 0.01], transwell chamber assay showed that the number of transfected cells that passed the transwell membrane was significantly less than those of control groups (77 ± 6 vs. 72 ± 8 vs. 48 ± 6, P < 0.01). Quantitative RT-PCR and Western blotting showed that the expression of bcl-2 mRNA and protein was markedly decreased and the expression of bax, caspase-3 were significantly increased. There was no significant change in the expression of FasL.

CONCLUSION

WWOX exerts its antitumor effect against proliferation through inducing cell apoptosis in cholangiocarcinoma.