OV6+ cancer stem cells drive esophageal squamous cell carcinoma progression through ATG7-dependent ß-catenin stabilization.

Cancer stem cells (CSCs) represent a subpopulation of tumor cells that exhibit capacities for tumor initiation and progression. Identifying CSCs and their related pathways is necessary for the development of new therapeutic targets against tumors. However, the molecular mechanism of CSCs in esophageal squamous cell carcinoma (ESCC) remains elusive. This study demonstrated that OV6 expression was closely associated with ESCC patients' clinical outcome and prognosis. OV6+ cells possessed stronger stem-like properties, including self-renewal, stem cell-associated gene expression, tumorigenicity, chemo-resistance, invasion, and metastasis. Autophagy maintained the stem-like properties of OV6+ cells by stabilizing ATG7-dependent ß-catenin. Furthermore, a significantly positive correlation between ATG7 and OV6 expression was detected in human ESCC biopsies, and this correlation could be used to predict ESCC patients' prognosis. Taken together, our findings provide a novel potential CSC marker for ESCC. OV6+ cancer stem cells can promote the progression of ESCC through ATG7-dependent ß-catenin stabilization. OV6 may serve as a novel prognostic biomarker and therapeutic target for ESCC patients.

Zinc finger protein X-linked promotes expansion of EpCAM+ cancer stem-like cells in hepatocellular carcinoma.

Zinc finger protein X-linked (ZFX) is frequently upregulated in multiple human malignancies and also plays a critical role in the maintenance of self-renewal in embryonic stem cells. However, the role of ZFX in liver cancer stem cells (CSCs) remains obscure. We observed that the elevated expression of both ZFX and epithelial cell adhesion molecule (EpCAM) was associated with aggressive clinicopathological features and indicated poor prognosis in patients with hepatocellular carcinoma (HCC). ZFX was commonly enriched in liver EpCAM+ CSCs. Knockdown of ZFX decreased the proportion of EpCAM+ CSCs in HCC cells and suppressed their expression of stemness-related genes, self-renewal capacity, chemoresistance, metastatic potential, and tumorigenicity. Conversely, upregulation of ZFX in CSCs rescued these inhibitory effects and enhanced stem-like properties. Mechanistically, depletion of ZFX reduced nuclear translocation and transactivation of ß-catenin, thereby inhibiting the self-renewal capacity of EpCAM+ CSCs. Moreover, knockdown of ß-catenin attenuated the self-renewal of EpCAM+ HCC cells stably expressing ZFX, further indicating that ß-catenin is required for ZFX-mediated expansion and maintenance of EpCAM+ CSCs. Taken together, our findings indicate that ZFX activates and maintains EpCAM+ liver CSCs by promoting nuclear translocation and transactivation of ß-catenin. Furthermore, combination of ZFX and EpCAM may serve as a significant indicator for prognosis of patients with HCC.