NF-kappaB P50/P65 hetero-dimer mediates differential regulation of CD166/ALCAM expression via interaction with micoRNA-9 after serum deprivation, providing evidence for a novel negative auto-regulatory loop

Abstract

CD166/ALCAM plays an important role in tumor aggression and progression as well as protecting cancer cells against apoptosis and autophagy. However, the mechanism by which pro-cell death signals control CD166 expression remains unclear. Here we show that following serum deprivation (SD), upregulation of CD166 protein is shorter than that of CD166 mRNA. Molecular analysis revealed both CD166 and miR-9-1 as two novel NF-κB target genes in hepatoma cells. In vivo activation and translocation of the NF-κB P50/P65 hetero-dimer into the nucleus following the phosphorylation and accompanied degradation of its inhibitor, IκBα, contributes to efficient transcription of both genes following SD. We show that following serum starvation, delayed up-regulation of miR-9 represses translation of CD166 protein through its target sites in the 3′-UTR of CD166 mRNA. We also propose that miR-9 promotes cell migration largely due to inhibition of CD166. Collectively, the study elucidates a novel negative auto-regulatory loop in which NF-κB mediates differential regulation of CD166 after SD.

CD166 plays a pro-carcinogenic role in liver cancer cells via inhibition of FOXO proteins through AKT

“…5F). These two types of proteins play opposing roles in the regulation of tumorigenesis in liver cancer (6,7,11,18,19). Nuclear localization of FOXO proteins induces expression of anti-carcinogenic genes (11), whereas CD166 facilitates translocation of FOXO proteins from the nucleus to the cytoplasm (Fig.…”

“…Bel-7402 cells (5x10 6 ) expressing proteins as indicated were subcutaneously injected into athymic nude mice (Bikai, Shanghai, China). Tumor size was measured every six days using a caliper, and the tumor volume was calculated as 0.5 x L x W 2 , with L indicating length and W indicating width.…”

“…Gene silencing of CD166 decreases the concentration of Bcl-2 and increases the level of apoptosis (PARP, active caspase-7) (5). We previously reported that the activation of anti-apoptotic canonical NF-κB signaling greatly induces CD166 expression in liver cancer cells after serum deprivation (6), suggesting its important roles in regulating apoptosis. Most recently, we revealed that CD166 can exert its anti-apoptotic role by enhancing YAP function, demonstrating that CD166 is an upstream regulator of YAP (7).…”

“…The FOX transcription factors that belong to the other (O) subfamily (FOXO) include four members (FOXO1, 3,4,6) in mammals (8). Overexpression of FOXO proteins inhibits tumor growth in vitro and tumor size in vivo (9).…”

Cloning and Expression of C2 and V Domains of ALCAM Protein in E. coli BL21 (DE3)

“…In addition, this protein performs a vital role in invasion and development of tumour in colorectal [14][15][16] and breast cancers [6].…”