PDIA6 exacerbates hepatocellular carcinoma via enhancing proteasome-dependent degradation of AKAP12.
TL;DR
This study experimentally validated that PDIA6 promotes the proliferation and metastasis of HCC cells and uncovered the HCC-promoting mechanism of the PDIA6-AKAP12-Wnt signaling axis and highlights its great potential for the development of therapeutic targets in HCC.
Abstract
The continuously rising incidence and persistently high mortality of hepatocellular carcinoma (HCC) have created an urgent need for a deeper understanding of the molecular mechanisms underlying this disease. In the present study, leveraging multiple HCC transcriptome databases, we employed expression analysis, correlation analysis, Gene Set Variation Analysis (GSVA), and cox regression analysis to identify that aberrant upregulation of PDIA6 represents a promising prognostic biomarker associated with adverse clinical outcomes in HCC. Using a series of in vitro oncology research approaches, as well as nude mouse models of subcutaneous tumor formation and lung metastasis, we experimentally validated that PDIA6 promotes the proliferation and metastasis of HCC cells. Through transcriptome sequencing analysis and subsequent rescue experiments, we further confirmed that PDIA6 enhances HCC cell proliferation and migration by activating the Wnt signaling pathway. Combined analysis via immunoprecipitation-mass spectrometry and proteomics revealed that PDIA6 significantly downregulates the expression of the tumor suppressor gene AKAP12. Subsequent rescue experiments demonstrated that PDIA6 drives HCC progression in a manner dependent on the reduced expression of AKAP12. Utilizing protein half-life assays, ubiquitination assays, and co-IP experiments, we uncovered the underlying mechanism: PDIA6 competitively binds to the UCH domain of USP24, which impairs the deubiquitinating activity of USP24 towards AKAP12. This ultimately leads to enhanced K48-linked ubiquitination of AKAP12 and its subsequent proteasomal degradation. We further verified, using specific activators, that AKAP12 inhibits the Wnt signaling pathway in a PKA-dependent manner. In vivo, targeted inhibition of PDIA6 exhibited a more potent therapeutic effect on Wnt-positive HCC tumors.Conclusion Collectively, our study demonstrates the HCC-promoting mechanism of the PDIA6-AKAP12-Wnt signaling axis and highlights its great potential for the development of therapeutic targets in HCC.