Interfering with UBE2L3 expression targets regulation of MLKL to promote necroptosis inhibition of growth in osteosarcoma.

Abstract

Background: In previous studies, elevated expression of UBE2L3 has been observed in osteosarcoma cells, and silencing UBE2L3 has been shown to promote oxidative stress and induce necroptosis. However, the exact molecular mechanisms underlying these findings remain unclear.

Objective: The purpose of this study is to investigate the molecular mechanisms by which interfering with UBE2L3 expression promotes necroptosis and impacts the progression of osteosarcoma, building upon previous in vitro cell experiments.

Methods: Osteosarcoma cells were transfected with shNC and shUBE2L3 plasmids, and the cells were injected into the right tibia of nude mice to establish a tumor xenograft model. The growth rate, changes in body weight, and tumor volume of the mice in each group were observed. After 15 days, the mice were sacrificed, and the tumors were dissected and analyzed for tumor volume. Immunohistochemical staining was performed to detect changes in the expression of necroptosis-related proteins, such as PCNA, p-MLKL, and p-RIP1. Additionally, U2OS and HOS cells were transfected with UBE2L3-silencing plasmids, and immunoprecipitation was performed to investigate the interaction between UBE2L3 and the necroptosis protein MLKL. By combining these experiments, we aim to evaluate the impact of UBE2L3 on necroptosis both in vitro and in vivo and elucidate its specific role in targeting MLKL to regulate necroptosis as a therapeutic approach for osteosarcoma.

Results: After interfering with UBE2L3, the growth rate of tumors in nude mice significantly slowed down, accompanied by a notable reduction in tumor volume and weight. These findings suggest that inhibiting the expression of UBE2L3 can suppress the growth of osteosarcoma. Furthermore, immunohistochemical analysis revealed that following UBE2L3 interference, the intensity of staining for the necrotic proteins p-MLKL and p-RIP1 was increased and PCNA staining was decreased, indicating that interfering with UBE2L3 expression can promote necroptosis. Moreover, through transfection of UBE2L3 silencing plasmids into osteosarcoma cells in vitro, immunoprecipitation and ubiquitination results demonstrated that UBE2L3 can specifically bind to MLKL. Overexpression of UBE2L3 promoted the ubiquitination of MLKL and reduced its expression. Thus, down-regulation of UBE2L3 could modulate downstream MLKL expression and promote necrosis of osteosarcoma cells.

Conclusion: UBE2L3 selectively binds to MLKL, exerting ubiquitination-mediated regulation on downstream MLKL. Decreased expression of UBE2L3 modulates MLKL expression and promotes necrosis, thereby inhibiting osteosarcoma growth.