Objective: To evaluate the effect of full-length cyclin B1 antisense cDNA (AS-CLB1) on chemosensitivity of Lewis lung carcinoma cells (LL/2) to gemicitabine (GEM) in vitro and in vivo and hence provide a therapeutic regiment for treating non-small cell lung (NSCL) cancer using AS-CLB1 combined with GEM.
Methods: Cell cycle phase distribution and apoptosis of LL/2 parent cells, LL/2/vect and LL/2/AS-CLB1 transfectants (LP, LV and LA cells) were determined by flow cytometry. In addition, the three kinds of cells were treated with GEM (20 nmol/L-20 micromol/L) in vitro for 1 h and 24 h respectively, and then cytotoxicity of GEM was measured by MTT assay. After inoculation with the three kinds of cells respectively, the C57BL/6 mice were treated with GEM [25 - 125 mg/(kg x day)] once every three days for four times when tumors developed; tumorigenicity and survival were observed and cell apoptosis in tumor tissues was determined by flow cytometry.
Results: LA cells displayed apparent apoptosis and G1 arrest compared with LP and LV cells (controls). Additionally, cytotoxicity of GEM to LA cells was more obvious than that to controls. Moreover, tumorigenicity was inhibited, cell apoptosis in tumor tissues was induced, and survival was evidently increased in LA cells group.
Conclusion: AS-CLB1 slightly increased the sensitivity of LL/2 cells to GEM in vitro and in vivo. The function of AS-CLB1 may be associated with its ability to enhance the anti-tumor activity of GEM by inducing cell apoptosis and G1 arrest.