期刊
FRONTIERS IN CELL AND DEVELOPMENTAL BIOLOGY
卷 8, 期 -, 页码 -出版社
FRONTIERS MEDIA SA
DOI: 10.3389/fcell.2020.575903
关键词
c-Myc; MICAL-L2; NSCLC; proliferation; deubiquitination
资金
- National Natural Science Foundation of China [81773107, 82073226, 81602561]
- Science Foundation of Jiangsu Commission of Health [Z2019056]
- Training Programs of Innovation and Entrepreneurship for Undergraduates by Jiangsu Province [201810312018Z]
- Nanjing Medical University Science and Technology Development Funds [NMUB2019003]
The study showed that MICAL-L2 is highly expressed in human NSCLC and plays a role in promoting cancer cell proliferation by interacting with and stabilizing c-Myc protein. Depletion of MICAL-L2 led to reduced c-Myc stability and decreased cancer cell proliferation. This suggests that MICAL-L2 may be a potential therapeutic target for NSCLC.
Objectives: MICAL-L2, a member of the molecules interacting with the CasL (MICAL) family, was reported to be highly expressed in several types of cancers, however, the roles of MICAL-L2 in NSCLC pathogenesis remain to be explored. This study is designed to clarify the mechanisms by which MICAL-L2 participates in NSCLC cell proliferation. Materials and Methods: The expression levels of MICAL-L2 in human lung cancer samples were assessed by immunohistochemical staining. Cells were transfected with siRNA or plasmids to regulate MICAL-L2 expression. Cell proliferation was measured by EdU staining and CCK-8 assays. MICAL-L2 and phosphorylated/total c-Myc expression were examined by Western blotting analysis. Interaction between MICAL-L2 and c-Myc was assessed by immunofluorescence staining, Western blotting and co-immunoprecipitation assays. Western blotting, polyubiquitylation detection and protein stability assays were used to assess whether MICAL-L2 exerts its oncogenic effect via c-Myc. Results: We found that MICAL-L2 was highly expressed in human NSCLC. While overexpressing MICAL-L2 increased NSCLC cell proliferation, MICAL-L2 depletion decreased the proliferation of NSCLC cells, an effect that was linked to cell cycle arrest. MICAL-L2 physically interacted with the c-Myc protein and functioned to maintain nuclear c-Myc levels and prolonged its half-life. Knockdown of MICAL-L2 expression led to decreased c-Myc protein stability through accelerating polyubiquitylation of c-Myc and gave rise to c-Myc degradation. We further found that MICAL-L2 deubiquitinated c-Myc and blocked its degradation, presumably by inhibiting c-Myc phosphorylation at threonine residue 58. Conclusions: These results indicate that MICAL-L2 is a key regulator of c-Myc deubiquitination and stability in the nucleus, and this activity may be involved in promoting NSCLC cell proliferation.
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