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Abstract Actin like protein 6A (ACTL6a), a subunit of the SWI/SNF chromatin remodeling complex, is amplified in a third of all squamous cell carcinomas including head and neck (HNSCC) cancers. Recent studies implicate ACTL6a as an oncogenic driver that potentiates SWI/SNF-related chromatin remodeling; however, the underlying mechanisms in HNSCC progression yet to be elucidated. Using the HNSCC cell lines FaDu, SCC90, and SCC2, ACTL6a knockdown (siACTL6a) led to a significant reduction in cell proliferation compared to control when measured by sulforhodamine B but not resazurin, suggesting up-regulation of oxidative phosphorylation with siACTL6a. We used RNA-seq datasets of siACTL6a in FaDu cells and found that there was a significant up-regulation of components of complex I and IV of the electron transport chain compared to control. Gene set enrichment analysis also demonstrated a significant up-regulation in glycolysis in ACTL6a amplified tumors within the HNSCC TCGA dataset. Since metabolism is a key driver of chemotherapy resistance, we studied effects of ACTL6a expression on cisplatin-mediated cytotoxicity. Compared to control, siACTL6A of the HNSCC cell lines FaDu and SCC2 had significantly decreased IC50 to cisplatin, indicating ACTL6a mediates toxicity. We also observed significantly decreased migration in a transwell migration assay in siACTL6A FaDu and SCC2 cells compared to control. We are studying the effects of shRNA directed against ACTL6a using a syngenic in vivo tumor model with a mouse oral cavity (MOC2) cell line that grows in C57BL/6J mice. Subcutaneous injection of MOC2 cells demonstrated significantly decreased tumor growth in shACTL6a cells compared to control. We are performing additional studies to identify specific mechanisms of ACTL6a mediated metabolic reprogramming in tumor cells. In conclusion, ACTL6A amplification is common in HNSCC and facilitates metabolic reprogramming, which drives tumor proliferation, cell migration, and drug resistance. Citation Format: Mehri Monavarian, Andrey Finegersh. ACTL6a drives metabolic reprogramming and chemoresistance in head and neck squamous cell carcinoma abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 3073.
Monavarian et al. (Fri,) studied this question.