E3 ligase SOCS3 regulates NOD2 expression by ubiquitin proteasome system in lung cancer progression.

Purpose: Despite lung cancer is one of the leading causes of cancer-related deaths, it remains hard to discover effective diagnostic and therapeutic approaches. Moreover, the five-year survival rate is relatively lower than other tumors. So urgent needs for finding a new theranostic target to treat lung cancer effectively. This study aims to present SOCS3 and NOD2 proteins as novel targets for diagnosis and therapy.

Methods: We first confirmed SOCS3 expression level in patients' tissues. Then, we applied knockdown and overexpression of SOCS3 on lung cancer cell lines and performed proliferation, migration, and invasion assay. After that, we found NOD2 is a target of SOCS3 and introduced overexpression of NOD2 to A549 for verifying reduced tumorigenicity of lung cancer cells.

Results: We identified protein expression level of SOCS3 was frequently higher in tumor tissues than adjacent normal tissues. Truly, overexpression of SOCS3 promoted proliferation, migration, and invasion capacity of lung cancer cells. We found that SOCS3 interacts with NOD2 and SOCS3 ubiquitinates NOD2 directly. Furthermore, lung cancer tissues with higher SOCS3 expression showed lower NOD2 expression. We confirmed overexpression of NOD2 leads to suppressed tumorigenicity of lung cancer cells, and these effects occurred through MAPK pathway.

Conclusion: Collectively, our work reveals novel roles of SOCS3 in lung tumorigenesis and proposes SOCS3 as a promising biomarker candidate for therapeutic and diagnostic target for lung cancer.