[Effects of tumor suppressing gene TIP30/CC3 on the growth of tumor cells].

OBJECTIVE: To introduce the newly found gene TIP30/CC3 into a hepatoma cell line PLC/PRF/5 and select the stable expression clones. The growth and cell cycles were studied with the clones stably expressing TIP30/CC3 or anti-TIP30/CC3, and the effects of TIP30/CC3 gene on hepatoma cells were analyzed. METHODS: The internal expression of TIP30/CC3 protein was detected with Western blot, then TIP30/CC3 or anti-TIP30/CC3 cDNA was subcloned into a constitutive vector pcDNA3 followed by transfection into PLC/PRF/5. Stable expression clones were selected. The cell growth curve was made and cell cycles detected using flow cytometry. To confirm the results in vitro, stable-expressing cells were implanted subcutaneously into nude mice and time of tumor formation recorded and tumor volume measured. RESULTS: PLC-anti-TIP30 grew faster than the others. Three days after transfection, live cells of PLC-anti-TIP30 were 14.0*10(4), in comparison with the control PLC-DNA3 and PLC/PRF/5, the differences were statistically significant. Live cells of PLC-TIP30 were 4.9*10(4), significantly less than the two control groups. Six days after transfection, live cells of PLC-anti-TIP30 were 25.0*10(4), significantly more than the controls PLC-DNA3 and PLC/PRF/5. Live cells of PLC-TIP30 were 12.4*10(4), significantly less than the two control groups. Cell cycle analysis showed that PLC-anti-TIP30 proliferated faster, 22.4% cells were in G0/G1 (gap) phases and 58.6% cells in S (DNA synthesis) phase. The growth of the PLC-anti-TIP30 cell was retarded and many cells were arrested from G1 to S phases. Cells in G0/G1 and S phase were 44.2% and 33.3% respectively. Furthermore, the average time of tumor formation was shorter in anti-TIP30 group and longer in TIP30/CC3 group, and times were 6.0 d (with control groups) and 15.6 d (with control groups) respectively. Tumors in the nude mice grew faster in PLC-anti-TIP30 group and slower in PLC-TIP30 group. CONCLUSION: Tumor suppressor gene TIP30/CC3 can inhibit the proliferation of tumor cells and interfere in its cell cycles. It can be used as a valuable tool for hepatoma biotherapy including gene therapy.