LRSAM1 E3 Ubiquitin Ligase Promotes Choriocarcinoma Progression and Metastasis via p53/p21 Signaling Impediment

OBJECTIVE: The E3 ubiquitin ligase LRSAM1 (LRSAM1) was involved in many cancers, but whether it exerts anti- or protumor efficacies on choriocarcinoma cellular structures remains unknown. We wanted to explore the efficacies of aberrant LRSAM1 expression on human choriocarcinoma cellular structures and the underlying mechanisms. METHODS: LRSAM1 mRNA expressions in choriocarcinoma lines of cells JEG-3 and JAR cellular structures, as well as HTR8/sev8 human trophoblastic cell line cellular structures, were assessed using assay analysis of quantitative real-time polymerase chain reactions. We compared cell proliferation, migratory flow, invasive force, adhesion, and apoptotic process between cellular structures infected with si-LRSAM1 plasmids versus negative controls using CCK-8, clone formation, Transwell, adhesion, and flow cytometry assays. Protein expressions of LRSAM1, E-cadherin, and N-cadherin (indicators of epithelial-mesenchymal transformation) and p53/p21 pathway components were quantitated using a Western blot assay. The morphology of tumor lesions was observed in xenografted nude mice using immunohistochemistry (IHC) analyses. RESULTS: LRSAM1 was markedly overexpressed within JEG-3 and JAR choriocarcinoma cellular structures compared to HTR8/sev8 trophoblast cellular structures. Compared to si-NC, LRSAM1 knockdown robustly restricted cell proliferating, migratory flow, invasive force, and adhesion and fueled apoptotic cell process in JEG-3 as well as JAR cellular structures and suppressed tumor growth, as evidenced by the reduction in tumor volume and weight in naked mice inoculated with transfected cellular structures. Compared to si-negative control (si-NC), si-LRSAM1 significantly decreased Ki67 (a proliferating indicator) and N-cadherin expressions but reduced E-cadherin expression in JEG-3 and JAR cellular structures. Blocking the p53/p21 pathway by pifithrin-a (a p53 restrictor) successfully reversed the anti-inhibitory effect of LRSAM1 depletion, resulting in enhanced proliferating and metastasis in JEG-3 and JAR cellular structures. CONCLUSION: LRSAM1 exerts tumorigenic roles in choriocarcinoma. Via the activating of the p53/p21 pathway of signaling and impediment of choriocarcinoma cell proliferating, migratory flow, and invasive force, LRSAM1 knockdown slows the course of the disease. For choriocarcinoma diagnosis and treatment, it serves as a new therapeutic target.