CSN8 is a key regulator in hypoxia-induced epithelial–mesenchymal transition and dormancy of colorectal cancer cells

Abstract

AbstractHypoxic stress plays a pivotal role in cancer progression; however, how hypoxia drives tumors to become more aggressive or metastatic and adaptive to adverse environmental stress is still poorly understood. In this study, we revealed that CSN8 might be a key regulatory switch controlling hypoxia-induced malignant tumor progression. We demonstrated that the expression of CSN8 increased significantly in colorectal cancerous tissues, which was correlated with lymph node metastasis and predicted poor patient survival. CSN8 overexpression induces the epithelial-mesenchymal transition (EMT) process in colorectal cancer cells, increasing migration and invasion. CSN8 overexpression arrested cell proliferation, upregulated key dormancy marker (NR2F1, DEC2, p27) and hypoxia response genes (HIF-1α, GLUT1), and dramatically enhanced survival under hypoxia, serum deprivation, or chemo-drug 5-fluorouracil treatment conditions. In particular, silenced CSN8 blocks the EMT and dormancy processes induced by the hypoxia of 1% O2 in vitro and undermines the adaptive capacity of colorectal cancer cells in vivo. The further study showed that CSN8 regulated EMT and dormancy partly by activating the HIF-1α signaling pathway, which increased HIF-1α mRNA expression by activating NF-κB and stabilized the HIF-1α protein via HIF-1α de-ubiquitination. Taken together, CSN8 endows primary colorectal cancer cells with highly aggressive/metastatic and adaptive capacities through regulating both EMT and dormancy induced by hypoxia. CSN8 could serve as a novel prognostic biomarker for colorectal cancer and would be an ideal target of disseminated dormant cell elimination and tumor metastasis, recurrence, and chemoresistance prevention.