The stromal-tumor amplifying STC1-Notch1 feedforward signal promotes the stemness of hepatocellular carcinoma

Abstract Background Cancer associated fibroblasts (CAFs), an important component of the tumor microenvironment (TME), play crucial roles in tumor stemness. Stanniocalcin-1 (STC1) was found secreted by CAFs in various cancers, but its main source and its role in hepatocellular carcinoma (HCC) was still unclear. Methods The serum and intracellular expression levels of STC1 were detected by ELISA and western blot. The role of CAFs-derived STC1 in HCC stemness was probed by sphere formation, sorafenib resistance, colony formation, and transwell migration and invasion assays in vitro and orthotopic liver xenograft tumor model in vivo. An HCC tissue microarray containing 72 samples was used to identify the STC1 and the Notch1 in HCC tissues. Co-immunoprecipitation (CoIP) and dual-luciferase reporter assay were performed to further explore the underlying mechanisms. ELISA assays were used to detect the serum concentration of STC1 in HCC patients. Results We demonstrated that CAFs were the main source of STC1 in HCC and that CAFs-derived STC1 promoted HCC stemness through the activation of the Notch signaling pathway. In HCC patients, the expression of STC1 was positively correlated with poor prognosis and the Nocth1 expression. Co-IP assay showed that STC1 directly bound to Notch1 receptors to activate the Notch signaling pathway, thereby promoting the stemness of HCC. Our data further demonstrated that STC1 was a direct transcriptional target of CSL in HCC cells. Furthermore, ELISA revealed that the serum STC1 concentration was higher in patients with advanced liver cancer than patients with early liver cancer. Conclusions CAFs-derived STC1 promoted HCC stemness via the Notch signaling pathway. STC1 might serve as a potential biomarker for the prognostic assessment of HCC, and the stromal-tumor amplifying STC1-Notch1 feedforward signal could provide an effective therapeutic target for HCC patients.