Mechanism of combined use of cyclopamine and hydroxycamptothecin in inducing the apoptosis of human oral squamous cell carcinoma cell line / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the mechanism underlying the effect of combined use of cyclonpamine and hydroxycamptothecin in inducing the apoptosis of human oral squamous cell carcinoma cell line (OSCC) HSQ-89.</p><p><b>METHODS</b>CCK8 assay was used to investigate the inhibitory effect of cyclopamine on HSQ-89 cells. Flow cytometry (FCM) was employed to examine the cell apoptosis following combined treatment with cyclonpamine and hydroxycamptothecin. Reverse transcription polymerase chain reaction (RT-PCR) was applied to detect the mRNA expressions of Bcl-2, Bcl-xl, and Bid in HSQ-89 cells after the treatments.</p><p><b>RESULTS</b>Combined treatment with cyclonpamine and hydroxycamptothecin significantly inhibited the cell proliferation compared with hydroxycamptothecin treatment alone, also resulting in a significantly higher apoptosis rate of the cells (P<0.05). The mRNA level of Bcl-2 was significantly decreased after the treatments, especially after the combined treatment. Cyclopamine produced no significant effect on the mRNA levels of Bcl-xl and Bid in the cells.</p><p><b>CONCLUSION</b>The combined use of cyclopamine and hydroxycamptothecin significantly down-regulates the expression on of bcl-2 to induce the apoptosis of human OSCC cell line HSQ-89.</p>

Epigallocatechin-3-gallate induces G1 phase cell cycle arrest in KB cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the effects of epigallocatechin-3-gallate (EGCG) on the proliferation of human oral epithelial cancer cell line KB cells and the molecular mechanisms.</p><p><b>METHOD</b>KB cells were treated with various concentrations of EGCG for 24 or 48 h. MTT assay was used to test the cell viability. The changes of cell cycle in KB cells treated with EGCG for 48 h were analyzed using flow cytometry. The expressions of cyclin A, cyclin D1 and cyclin E were detected by RT-PCR and Western blotting.</p><p><b>RESULT</b>The viability of KB cells treated with various concentrations of EGCG (25, 50, 100, 200, 400, and 800 micromol/L) for 48 h were decreased to (85.4-/+2.4)%, (80.4-/+2.8)%, (51.5-/+4.5)%, (30.2-/+1.9)%, (25.3-/+1.5)%, (20.0-/+1.1)%, respectively, showing significant difference from that of the control group [(100.0-/+2.2)%, P<0.05). EGCG decreased the viabilities of KB cells in a dose-dependent manner. Flow cytometry demonstrated that treatment with EGCG significantly increased the cell percentage in sub-G1 phase, which was (73.5-/+4.4)% after a 48-h EGCG treatment, significantly different from that in the control group [(47.3-/+3.5)%, P<0.05). EGCG-induced G1 phase arrest was correlated to the down-regulation of cyclin A and cyclin E.</p><p><b>CONCLUSION</b>EGCG inhibits the proliferation of KB cells by inducing G1 phase arrest, which involves the downregulation of cyclin E.</p>