Targeting protein hyperSUMOylation halts cholangiocarcinoma progression by impairing cancer cell viability and tumor-stroma crosstalk.

Background And Rationale: Cholangiocarcinoma (CCA) includes a diverse group of biliary malignancies with poor prognosis. Alterations in post-translational modifications contribute to disrupted protein dynamics, cellular disturbances, and disease. This study investigates the role of protein SUMOylation in cholangiocarcinogenesis and its potential as a therapeutic target.

Approach And Results: Analysis of CCA tumors from four patient cohorts and CCA cell lines, revealed increased expression of the SUMOylation machinery genes SAE1 and UBE2I , regardless of the tumor's molecular profile, resulting in elevated levels of SUMO1-conjugated proteins. Higher SAE1 and UBE2I levels were both indicative of unfavorable clinical outcomes. Deregulated SUMOylated proteins in CCA, mostly linked to cell proliferation, survival, and homeostasis, were identified through immunoprecipitation and mass spectrometry. Genetic ( UBE2I -knockdown) and pharmacological (ML792 and SAMe) inhibition of SUMOylation effectively suppressed tumorigenesis in subcutaneous and oncogene-driven CCA models, reducing the presence of cancer-associated fibroblasts (CAFs) and increasing the recruitment of anti-tumor immune cells. In vitro , targeting SUMOylation induced CCA cell death and reduced cell proliferation, colony formation, and spheroid growth. Importantly, ML792 and SAMe did not adversely affect normal human cholangiocytes. Moreover, co-culture of wild-type or UBE2I -knockdown CCA cells with CAFs revealed that depleting SUMOylation in CCA cells impaired CAF cell growth and altered their protein secretome, ultimately disrupting CCA growth through a regulatory feedback loop.

Conclusion: Aberrant SUMOylation drives CCA progression by enhancing cell survival, proliferation, and shaping the tumor microenvironment. Targeting SUMOylation shows potential in inhibiting CCA growth, representing a promising therapeutic strategy.