Campothecin suppresses cell proliferation and migration in head and neck squamous cell carcinoma by blocking RAB27A-mediated phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT) pathway.

Camptothecin (CPT), a naturally occurring alkaloid derived from the Camptotheca acuminate plant, exerts anti-tumor properties. However, its specific impact on head and neck squamous cell carcinoma (HNSCC) remains uncertain. The study was to explore the action and mechanism of CPT on HNSCC cells. First, two HNSCC cell lines (FaDu and TU686) and a normal immortalized keratinocyte (HEK001) cell line, were exposed to a spectrum of CPT concentrations (ranging from 10 to 50 μM) for durations of 24 h and 48 h. Cell viability, proliferation, migration, and invasion were assessed by CCK-8 assay, EdU incorporation assay, wound healing assay and transwell assay. Subsequently, si-RAB27A or negative control (NC) was introduced into FaDu and TU686 cells through transfection, and the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway was manipulated with L740Y-P, an activator of this pathway. The expression of proliferating cell nuclear antigen (PCNA), E-cadherin, PI3K/AKT signaling factors and RAB27A were determined by Western blot analysis. RAB27A was detected by immunofluorescence assay. It was found that CPT significantly hindered the viability, proliferation (p<0.01), migration (p<0.001), and invasion (p<0.001) of FaDu and TU686 cells. At the molecular level, administration of CPT caused a decline in the expression of PCNA, P-PI3K, P-AKT, and RAB27A, alongside an elevation in E-cadherin levels within HNSCC cells (p<0.05, p<0.01 and p<0.001). Reducing RAB27A expression enhanced the suppressive impacts of CPT on HNSCC cell viability (p<0.05 and p<0.01), migration (p<0.001) and invasion (p<0.01), these effects that were reversed upon treatment with L740Y-P in HNSCC cells (p<0.001). In summary, our study highlights the efficacy of CPT in HNSCC, demonstrating its influence on cell processes via the RAB27A-mediated PI3K/AKT pathway.