SERPINA12 promotes the tumorigenic capacity of stem cells in hepatocellular carcinoma through hyperactivation of AKT / [beta]-catenin signaling

Abstract

Hepatocellular carcinoma (HCC) is a highly heterogeneous and aggressive disease with poor prognosis. Emerging evidence underscores the profound interplay between phenotypic plasticity and cancer stemness properties in driving tumor recurrence, metastasis, and therapeutic resistance in HCC. Gaining a comprehensive understanding of the mechanisms governing cancer stemness is paramount for developing advanced therapeutic strategies. CD133 based on our previous findings and those of other researchers, has emerged as a prominent functional marker of liver cancer stem cells (CSCs). Unfortunately, CD133 is not specific to HCC but is also expressed in the fetal and regenerating liver. Thus, it is critical to identify specific molecular players and signal transduction pathways that are specific to CD133 + liver cancer cells to further design target drugs that interfere with CSC, while preserving normal stem cell function. Transcriptome profiling of epithelial-specific ‘normal’ CD133 + cells isolated from fetal and regenerating liver against ‘HCC’ CD133 + cells isolated from proto-oncogene driven (NRas / AKT HTVI mice model) and inflammation-associated HCC (DEN+CCl4 mice model) revealed preferential overexpression of serpin family A member 12 (SERPINA12) in HCC but not fetal and regenerating liver CD133 + cells. Moreover, SERPINA12 was consistently elevated across various etiology-driven HCC models, indicating its universal upregulation regardless of the specific underlying causes of HCC development. Furthermore, a noteworthy association between the expression of CD133 and SERPINA12 was observed in these mouse models, further underscoring their interconnected role in HCC progression and stemness. Clinically, SERPINA12 upregulation in HCC is closely associated with aggressive cancer features including poor survival, advanced tumor stage, cirrhosis, stemness signatures resembling embryonic stem cells, oncogenic differentiation, and undifferentiated HCC status. Mechanistically, SERPINA12 enrichment in HCC is mediated by the binding of TCF7L2, a well-known downstream effector of β-catenin, to the promoter region of SERPINA12, leading to its transcriptional activation. Functional characterization revealed a unique and previously unexplored role of endogenous SERPINA12 in enhancing self-renewal capability, resistance to therapy, and metastatic abilities both in vitro and in vivo. Besides, this observed effect was attributed to the interaction of SERPINA12 with GRP78, resulting in the hyperactivation of the AKT / GSK3β / β-catenin signaling cascade, which in turn formed a positive feed-forward loop. To validate the therapeutic potential of targeting SERPINA12, rAVV8-shSerpina12 was intravenously administered, which yielded promising outcomes. This approach sensitized HCC cells to Sorafenib treatment and impeded the CSC population in an immunocompetent HCC mouse model. Collectively, our findings highlight the preferential overexpression of SERPINA12 in CD133 + epithelial HCC cells and its significant contribution to HCC initiation and progression through the AKT / β-catenin feed-forward loop. Targeting SERPINA12 holds significant promise as a therapeutic strategy to specifically target CSCs.