ELAVL1 Promotes Proliferation and Inhibits Apoptosis of the Marek’s Disease Virus (MDV)-Transformed Cell Line MSB1 via the COX-2/PGE2 Pathway

Marek's disease (MD), caused by the oncogenic Marek's disease virus (MDV), is a highly contagious avian infection that induces lymphoproliferative tumors. The RNA-binding protein ELAVL1 is known to regulate tumor cell proliferation and apoptosis, but its role in MDV-induced oncogenesis remains unclear. This study investigated whether ELAVL1 modulates proliferation and apoptosis in the MDV-transformed MSB1 cell line and whether its effects involve the cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE2) pathway. MSB1 cells were transiently transfected with <i>ELAVL1</i>-overexpressing plasmids (pEGFP-C-ELAVL1) or <i>ELAVL1</i>-specific siRNA, with expression confirmed by real-time PCR (qRT-PCR). Cell proliferation was assessed using the CCK-8 assay, while cell cycle distribution and apoptosis rates were analyzed by flow cytometry. COX-2 and PGE2 expression levels were determined by qRT-PCR, Western blotting, and ELISA. Overexpression of ELAVL1 significantly promoted the proliferation of MSB1 cells, decreased transition into the G1 phase, increased the proportions of S and G2 phase cells, and suppressed apoptosis. Correspondingly, both mRNA and protein levels of COX-2 and PGE2 were significantly elevated. Conversely, ELAVL1 knockdown significantly inhibited proliferation, induced G1 phase arrest, decreased S phase cells, and significantly decreased COX-2 and PGE2 expression. These findings indicate that ELAVL1 promotes proliferation and inhibits apoptosis in MDV-transformed MSB1 cells, potentially via the COX-2/PGE2 signaling pathway.