Carboxypeptidase Vitellogenic-Like Promotes the Proliferation and Metastasis of Osteosarcoma through the TGF-ß/Smad Signaling Pathway.

ABSTRACT

OBJECTIVE: This research explored the biological role and underlying mechanisms of carboxypeptidase vitellogenic-like (CPVL) in the progression of osteosarcoma. METHODS: Through mining of microarray data from the GEO database and utilization of qRT-PCR and Western blot analyses, CPVL expression in osteosarcoma tissues and cells was evaluated. RNA interference and lentiviral transduction techniques were applied to edit the CPVL gene. RNA-seq was used to screen for the downstream target genes of CPVL. RESULTS: In both osteosarcoma biopsy samples and cell lines, the expression of CPVL was abnormally higher than that in normal cells or osteoblasts. CPVL silencing notably inhibited the proliferative activity of osteosarcoma cells, whereas CPVL overexpression had the opposite effect. CPVL silencing had potent tumor-suppressive ability in a xenograft osteosarcoma model in nude mice. CPVL silencing significantly suppressed osteosarcoma cell migration, invasion and EMT, whereas CPVL overexpression accelerated these events. Downstream genes related to the occurrence and development of osteosarcoma, including TGF-ß/Smad signaling pathway molecules (TGF-ß2, TGF-ßR1, Smad2/3, and Smad5), were suppressed by CPVL silencing. CONCLUSIONS: High CPVL expression in osteosarcoma not only promoted tumor growth but also induced the EMT process through the TGF-ß/Smad signaling pathway. CPVL may be a new antitumor therapeutic target for osteosarcoma.