CADM1 promotes malignant features of small-cell lung cancer by recruiting 4.1R to the plasma membrane

https://doi.org/10.1016/j.bbrc.2020.11.121Get rights and content
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Highlights

  • CADM1 promotes anchorage-independent growth of SCLC cells through the 4.1 proteins.

  • CADM1 recruits 4.1R to the cell-cell contact sites of SCLC cells.

  • Co-expression of CADM1 and 4.1R associates with advanced tumor grade of SCLC.

Abstract

Cell adhesion molecule 1 (CADM1), which mediates intercellular adhesion between epithelial cells, is shown to be highly expressed in small-cell lung cancer (SCLC) and to enhance tumorigenicity of SCLC cells in nude mice. Here, we investigated the molecular mechanism underlying the oncogenic role of CADM1 in SCLC. CADM1 promoted colony formation of SCLC cells in soft agar. Analysis of deletion and point mutants of the conserved protein-binding motifs in CADM1 revealed that the 4.1 protein-binding motif in the cytoplasmic domain is responsible for the promotion of colony formation. Among the actin-binding 4.1 proteins, 4.1R was the only protein whose localization to the plasma membrane is dependent on CADM1 expression in SCLC cells. Knockdown of 4.1R suppressed the colony formation enhanced by CADM1, suggesting that 4.1R is required for the oncogenic role of CADM1 in SCLC. In primary SCLC, CADM1 expression was correlated with membranous localization of 4.1R, as was observed in a SCLC cell line. Moreover, membranous co-localization of CADM1 and 4.1R was associated with more advanced tumor stage. These results suggest that the formation of CADM1–4.1R complex would promote malignant features of SCLC.

Keywords

Cell adhesion molecule
Small-cell lung cancer
CADM1
4.1R

Abbreviations

ATLL
adult T-cell leukemia/lymphoma
CADM1
cell adhesion molecule 1
MAGuK
membrane-associated guanylate kinase homolog
PDZ
PSD95/Dlg/ZO-1
SCLC
small-cell lung cancer

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