7-Epitaxol induces apoptosis in cisplatin-resistant head and neck squamous cell carcinoma via suppression of AKT and MAPK signalling.

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide. Although cisplatin-based chemotherapy is commonly used in HNSCC, frequent development of cisplatin resistance is a potential cause of poor HNSCC prognosis. In the present study, we investigated the anticancer efficacy of a major paclitaxel metabolite namely 7-Epitaxol in cisplatin-resistant HNSCC. The findings revealed that 7-Epitaxol exerts cytotoxic effects in cisplatin-resistant HNSCC cell lines by inducing cell cycle arrest and intrinsic and extrinsic apoptotic pathways. Specifically, 7-Epitaxol increased Fas, TNF-R1, DR5, DcR3 and DcR2 expressions, reduced Bcl-2 and Bcl-XL (anti-apoptotic proteins) expressions, and increased Bid and Bim L/S (pre-apoptotic proteins) expressions, leading to activation of caspase-mediated cancer cell apoptosis. At the upstream cell signalling level, 7-Epitaxol reduced the phosphorylation of AKT, ERK1/2 and p38 to trigger apoptosis. In vivo results showed that animals treated with 7-Epitaxol show antitumor growth compared to control animals. Taken together, the study demonstrates the potential anticancer efficacy of 7-Epitaxol in inducing apoptosis of cisplatin-resistant HNSCC cells through the suppression of AKT and MAPK signalling pathways.