Objective To investigate the effect and potential mechanism of bufotalin on growth of human head and neck squamous cell carcinoma (HNSCC). Methods The effect of bufotalin on viability and proliferation of Cal-27 and FaDu cells were observed by CCK-8 method and plate clone formation experiment. The effect of bufotalin on cell cycle distribution of Cal-27 and FaDu cells were detected by flow cytometry. Western blotting was used to detect the effect of bufotalin on expressions of cyclin-dependent kinase 4 (CDK4) and cyclin D1 in Cal-27 and FaDu cells. To further explore the anti-tumor effects of bufotalin in vivo, a xenograft tumor model of HNSCC was established in nude mice. Proteomics technology was applied to identify differentially expressed proteins in bufotalin-treated Cal-27 cells, and the associated signaling pathways underlying its anti-tumor effect were analyzed. Western blotting was performed to assess the expressions of protein kinase R-like endoplasmic reticulum kinase (PERK)/eukaryotic initiation factor 2α (eIF2α) signaling pathway related proteins. Results In vitro experimental results showed that bufotalin significantly reduced the viability of Cal-27 and FaDu cells (P < 0.01, 0.001), inhibited their proliferation (P < 0.01, 0.001), induced cell cycle arrest in G₀/G₁ phase (P < 0.05, 0.01, 0.001), down-regulated the protein expressions of CDK4 and cyclin D1 in FaDu cells (P < 0.05, 0.001), and down-regulated the protein expression of CDK4 in Cal-27 cells (P < 0.05). The in vivo experimental results showed that bufotalin could significantly inhibit the growth of tumors in tumor bearing mice (P < 0.01, 0.001). Proteomics and IPA analysis showed that bufotalin could induce endoplasmic reticulum stress and up-regulate the expression levels of p-PERK and p-eIF2α in Cal-27 and FaDu cells (P < 0.05, 0.001). Conclusion Bufotalin could induce endoplasmic reticulum stress, activate EIF2 signaling pathway, and induce the arrest of HNSCC cells in G₀/G₁ phase, thereby inhibiting tumor cell proliferation and tumor growth in tumor-bearing mice.

bufotalin  /  head and neck squamous cell carcinoma  /  cell proliferation  /  cycle arrest  /  endoplasmic reticulum stress  /  EIF2 signaling pathway