ARMCX1 inhibits lung adenocarcinoma progression by recruiting FBXW7 for c-Myc degradation

Armadillo Repeat Containing X-Linked 1 (ARMCX1), a member of the ARM Repeat X-linked protein family, exerts inhibitory function in various tumors. However, its biological role in lung adenocarcinoma (LUAD) and the underlying molecular mechanisms require further exploration. LUAD tissue microarrays and bioinformatic databases were used to evaluate the relationship between ARMCX1 and clinicopathological features. The influence of ARMCX1 on LUAD cell proliferation, migration, and invasion in vitro was determined by colony formation, CCK-8, EdU incorporation, cell cycle, wound healing, and Transwell assays. The impact of ARMCX1 on LUAD cell growth and metastasis in vivo was determined by subcutaneously transplanted tumor and pulmonary metastasis assays. Western blot, immunoprecipitation, immunofluorescence, cycloheximide, and proteasome inhibitor assays were finally conducted to explore the potential underlying molecular mechanisms. ARMCX1 expression was downregulated in clinical LUAD samples due to which patient prognoses were poor. Functional experiments indicated that ARMCX1 overexpression inhibited the growth and metastasis of LUAD cells in vitro and in vivo. The molecular mechanism suggested that ARMCX1 recruits the E3 ubiquitin ligase FBXW7 for mediating ubiquitinated degradation of c-Myc, suppressing its nuclear accumulation, and ultimately inactivating cell cycle and epithelial-mesenchymal transition (EMT) signals. ARMCX1 inhibits LUAD cell proliferation and metastasis by interacting with c-Myc and enhancing its ubiquitination and degradation. Consequently, it can act as a tumor suppressor in this disease. These results suggest that ARMCX1 is a potential target in the treatment of LUAD.