Abstract P50: PAX9 Activates Cell Death via Autophagic Degradation of EGFR in Oral squamous Cell Carcinoma

Abstract

Abstract PAired boX 9 (PAX9) gene belongs to the PAX family and is critically essential for physiology and development. It has a significant role in maintaining squamous cell differentiation, and its downregulation is associated with tumor initiation and malignant transformation. In this study, we have analyzed the tumor suppressive potential of PAX9 by activating autophagy-dependent apoptosis in oral squamous cell carcinoma (OSCC). PAX9 overexpression inhibited cell growth and triggered apoptosis in OSCC. Moreover, PAX9 restricted orosphere formation and epithelial-mesenchymal transition in OSCC. Similarly, overexpression of PAX9 in OSCC induced autophagy activation and displayed enhanced lysosomal function in the transcriptional-dependent mechanism. Interestingly, PAX9-activated autophagy caused EGFR degradation leading to OSCC inhibition, thus establishing that PAX9 could induce lethal autophagy. In addition, PAX9 involves chemosensitizing OSCC to anticancer drugs, which exhibited profound growth inhibitory potential in OSCC. To check the status of PAX9 expression in OSCC in patient tissue, we performed IHC, and surprisingly, the expression of PAX9 was found to decreased in a higher grade of cancer tissues compared to the normal tissues. Further, we established a DMBA-induced oral carcinoma in hamster model, and it was observed that the expression of PAX9 was decreased in the 12th and 16th weeks of DMBA-exposed tissue compared to the normal tissue. On a mechanistic view, PAX9 expression was reduced with enhanced expression of DNMT1 in exposure to carcinogen in OSCC in vitro, indicating a potential association of methylation in controlling the expression of PAX9 during carcinogenesis. Citation Format: Chandra Sekhar Bhol, Gautam Sethi, Sujit Kumar Bhutia. PAX9 Activates Cell Death via Autophagic Degradation of EGFR in Oral squamous Cell Carcinoma [abstract]. In: Proceedings of Frontiers in Cancer Science; 2023 Nov 6-8; Singapore. Philadelphia (PA): AACR; Cancer Res 2024;84(8_Suppl):Abstract nr P50.