SERPINH1 secretion by cancer-associated fibroblasts promotes hepatocellular carcinoma malignancy through SENP3-mediated SP1/SQLE pathway.

Cancer-associated fibroblasts (CAFs) have garnered significant attention due to their ability to shape the tumor microenvironment, thereby facilitating tumor progression and metastasis. Serpin peptidase inhibitor clade H member 1 (SERPINH1) is known for its role in the proper folding and secretion of collagen. However, its biological significance in hepatocellular carcinoma (HCC) remains unclear. We observed higher levels of SERPINH1 in the conditioned medium (CM) of CAFs compared to normal fibroblasts (NFs) via ELISA assays. To investigate its impact on HCC, we knocked down SERPINH1 in CAFs by shRNA, which led to a notable reduction in HCC cell proliferation, migration, and invasion induced by CM of CAFs, measured by colony formation and Transwell assays. SERPINH1 also inhibited HCC cell apoptosis, decreased the percentage of cells arrested in the G0/G1 phase, and increased the proportion of cells in the S phase, which were detected by flow cytometry. We further performed co-injections of HepG2 cells liver orthotopic transplantation model with either shCtrl-CAFs or shSERPINH1-CAFs. Interestingly, the presence of shCtrl-CAFs significantly enhanced tumor-initiating capacity compared to HepG2 cells alone or when co-injected with shSERPINH1-CAFs. Mechanistically, CAFs-derived SERPINH1 activated the SENP3/SP1 signaling pathways, substantially promoting the growth of HCC cells. Notably, we found that the transcription factor SP1 directly binds to the SQLE promoter and activates its transcription via ChIP-qPCR assay. Inhibition of SP1 expression using the specific inhibitor plicamycin effectively reversed CAFs-derived SERPINH1-induced HCC growth in vivo. Collectively, our findings highlighted the pathological role CAFs-derived SERPINH1 played in driving malignant of HCC cells through the SENP3/SP1/SQLE signaling axis, which offered a explanation of how SERPINH1 promotes HCC progress. Besides, we also demonstrated that targeting SERPINH1 signaling shall be a promising direction to develop effective therapeutical strategies for anti-HCC clinical management.