Cytoskeleton remodeling caused by keratin dysregulation triggers tumor aggressiveness via promoting genomic instability and cellular adaption
Cellular architecture depends on keratin intermediate filament as a fundamental component, which offers essential mechanical support to fight environmental stresses. Our previous research demonstrated that keratin fusion variants increase tumor aggressiveness through enhanced cancer stemness in oral squamous cell carcinoma. The proper functioning of keratins plays an essential role in maintaining cell structure while determining cell fate. The present study demonstrates that keratin fusion variant drives genomic instability through cytokinesis defects, which results in the formation of polyaneuploid cancer cells (PACC). The cells expressing keratin fusion show elevated DNA damage repair gene expression, which serves as a key factor for mitotic slippage during cancer development. The PACCs generated by keratin fusion make cancer cells resistant to cisplatin treatment while simultaneously reducing {gamma}-H2AX induction and increasing survival rates. The Gene Set Enrichment Analysis results showed increased "regulation of actin cytoskeleton" activity in keratin fusion-expressing cells correlated with elevated actin filament networks and increased cell motility in these cells. In summary, the keratin fusion variant enhances cancer aggressiveness through three mechanisms: it creates genomic instability that leads to PACC formation and enables cancer cells to evade cGAS/STING-mediated death signals and modifies cytoskeleton structures, which results in drug resistance and metastasis.