RhoA/ROCKs signaling is increased by treatment with TKI‐258 and leads to increased apoptosis in SCC‐4 oral squamous cell carcinoma cell line

Background This study evaluated the effect of treatment with TKI‐258 on apoptosis, involving Rho GTPases and their effectors in SCC‐4 cells of oral squamous cell carcinoma. Methods Markers of cell death and apoptosis were analyzed in control and TKI‐258‐treated SCC‐4 cells by flow cytometry. The involvement of Rho GTPases and effectors in the induction of apoptosis by TKI‐258 was evaluated by quantification of cleaved PARP. Also, gene expression analysis of those proteins was performed. Results The treatment with TKI‐258 led to a significant increase in cell death (7‐AAD) and apoptosis (annexin V and cleaved PARP). When Rho GTPases were stimulated with LPA and inhibited with toxin A Clostridium difficile, the percentage of apoptotic cells increased and decreased, respectively. A similar effect was found when the treatment was with TKI‐258 combined with LPA and toxin A. Treatment with TKI‐258 significantly increased RhoA gene expression, while RhoB, RhoC, Rac1, and Cdc42 decreased significantly. ROCKs inhibitors (Y‐27632 and HA‐1077) reduced apoptosis compared with control. TKI‐258 combined with Y‐27632 or HA‐1077 led to an increase in apoptosis compared with inhibitors only. Treatment with TKI‐258 led to an increase in ROCK1 and ROCK2 gene expression, and a decrease in PAK1 and PAK2 gene expression. Conclusions TKI‐258 stimulates apoptosis in SCC‐4 cells of oral squamous cell carcinoma. Possibly, RhoA GTPase and their effectors ROCKs participate in the signaling pathway inhibited by TKI‐258. Clinical Relevance: Therapies with multi‐target inhibitors, such as TKI‐258, may be promising alternatives for the clinical treatment of oral squamous cell carcinoma.