Expression of Hedgehog signaling pathway genes in human oral squamous cell carcinoma and the effects of specific Hedgehog pathway inhibitor (Cyclopamine) on the proliferation and apoptosis of human oral epidermoid HSQ-89 cells

Abstract

Objective To investigate the expression of Hedgehog signaling pathway genes in human oral squamous cell carcinoma (OSCC), and the effects of specific Hedgehog pathway inhibitor ( Cyclopamine) on the proliferation and apoptosis of human oral epidermoid HSQ-89 cells. Methods The expression of Hedgehog signaling pathway components ( Shh, Smo, Ptch, Gli-1 ) was detected in 80 cases of human OSCC by immunochemistry. CCK8 assay was used to investigate the inhibition of Cyclopamine on HSQ-89 cells proliferation in vitro. Flow eytometry (FCM) was used to examine the effects of Cyclopamine on apoptosis of HSQ-89 cells. Reverse transcription polymerase chain reaction (RT-PCR) was applied to detect the mRNA expression of bcl-2, bcl-xL, and Bid in HSQ-89 cells. Results The positive expression rate of Shh, Smo, Ptch and Gli-1 was 61.25%, 56. 25%, 47. 50%, 53.75% in 80 cases of human OSCC tissue slices, respectively. After the cells were treated with different concentrations of Cyclopamine (0, 5,10, 20, 40, 80 μmoL/L, respectively ), the growth inhibition rate was 0, 3.0%, 4. 5%, 28.2%,51.2%, 62. 7% respectively; the apoptosis rate 3.01% ,3. 36% ,5. 70% ,9.42% respectly. Cyclopamine significantly inhibited cell proliferation ( P < 0. 05 ). FCM revealed that the apoptosis rate of HSQ-89 cells was significantly higher after exposure to Cyclopamine than in control groups (P < 0. 05 ). The mRNA levels of bcl-2 were significantly decreased, but Cyclopamine had no significant effects on the mRNA level and protein secretion of bcl-xL, Bid. Conclusion The expression of main hedgehog signaling pathway components was detected in human OSCC. Cyclopamine specifically inhibited the proliferation and the mRNA expression of bcl-2 in HSQ-89 cells. Key words: Oral squamous cell carcinoma; Signal transduction; Apoptosis; Proliferation; Cyclonpamine