Cisplatin-Induced Sonic Hedgehog Signaling Mediates Epithelial-Mesenchymal Transition in Hertwig’s Epithelial Root Sheath Cells

: In this study, we determined whether cisplatin can induce epithelial-mesenchymal transition (EMT) via the activation of Sonic hedgehog (Shh) or glioma-associated antigen-1 (Gli1) signaling pathway in mouse Hertwig’s epithelial root sheath (HERS) cells using a genetic knockdown approach. HERS cells treated with a low concentration of cisplatin (0.5 µM) for 24 h showed no reduction in the cell viability; however, there was a significant increase in the percentages of nu clear staining with γH2AX as compared to that with untreated control cells, indicating that 0.5 µM cisplatin induces DNA damage. Further, 0.5-µM cisplatin-treated cells provided an induction of EMT, showing decreased and increased expression of epithelial and mesenchymal markers, respectively. Enhancement in the EMT activity in cisplatin-treated HERS cells was correlated with increased expression of Shh and accelerated translocation and accumulation of Gli1 expression into the nucleus. The RNA interference-mediated silencing of Gli1 suppressed the acceleration of EMT in cisplatin-treated HERS cells; this was confirmed by no down-regulation or up-regelation in the expression of E-cadherin and vimentin, respectively, along with no increased expression of Snail expression. These findings suggest that the activation of Shh/Gli1 signaling pathway may be required for the enhancement of EMT in cisplatin-treated HERS cells. concentration the activation Shh/Gli1 signaling pathway by of DNA damage. by the following observations: (a) low concentration of cisplatin (0.5 µM) induces DNA damage; however, this concentration does not reduce the cell viability; (b) cisplatin-induced EMT is examined on the basis of downregulated and up-regulated expression of epithelial and mesenchymal markers, respectively; (c) the cispla-tin-treated HERS cells increased Shh and Gli1 expressions; (d) Transfection of Gli1 siRNA into the HERS cells reveals a significant suppression of cisplatin-induced EMT.