MiR-223 Suppresses Cell Proliferation by Targeting IGF-1R

Abstract

To study the roles of microRNA-223 (miR-223) in regulation of cell growth, we established a miR-223 over-expression model in HeLa cells infected with miR-223 by Lentivirus pLL3.7 system. We observed in this model that miR-223 significantly suppressed the proliferation, growth rate, colony formation of HeLa cells in vitro, and in vivo tumorigenicity or tumor formation in nude mice. To investigate the mechanisms involved, we scanned and examined the potential and putative target molecules of miR-223 by informatics, quantitative PCR and Western blot, and found that insulin-like growth factor-1 receptor (IGF-1R) was the functional target of miR-223 inhibition of cell proliferation. Targeting IGF-1R by miR-223 was not only seen in HeLa cells, but also in leukemia and hepatoma cells. The downstream pathway, Akt/mTOR/p70S6K, to which the signal was mediated by IGF-1R, was inhibited as well. The relative luciferase activity of the reporter containing wild-type 3′UTR(3′untranslated region) of IGF-1R was significantly suppressed, but the mutant not. Silence of IGF-1R expression by vector-based short hairpin RNA resulted in the similar inhibition with miR-223. Contrarily, rescued IGF-1R expression in the cells that over-expressed miR-223, reversed the inhibition caused by miR-223 via introducing IGF-1R cDNA that didn't contain the 3′UTR. Meanwhile, we also noted that miR-223 targeted Rasa1, but the downstream molecules mediated by Rasa1 was neither targeted nor regulated. Therefore we believed that IGF-1R was the functional target for miR-223 suppression of cell proliferation and its downstream PI3K/Akt/mTOR/p70S6K pathway suppressed by miR-223 was by targeting IGF-1R.

miR-223 reverses experimental pulmonary arterial hypertension

“…Thus, we could also speculate that miR-223 downregulation can also lead to increased KLF5 expression observed in PAH (8). Moreover, downstream miR-223 targets IGF-1R and HSP90␤ seem to act on proliferation through the phosphatidylinositol 3-kinase, Akt, and mammalian target of rapamycin (PI3K/Akt/ mTOR) pathway (13,18) known to play a role in PAH pathophysiology (10,26,36).…”

“…Other downstream targets of miR-223 not explored in the current study might also contribute to PAH development including F-box and WD repeat domain-containing 7 (FBW7), insulin-like growth factor 1 receptor (IGF-1R), and heat shock protein 90␤ (HSP90␤), as they all play a role in cell proliferation and apoptosis in cancer (13,18,38), which share many similarities with PAH (31). Wang et al (38) demonstrated that miR-223 is a repressor of FBW7, which regulates Kruppel-like factor 5 (KLF5) expression.…”

Serum microRNA expression profiling in patients with multiple system atrophy

“…It has been demonstrated that upregulation of miR-223 is associated with the pathophysiology of infection, inflammation and cancer (30). An in vitro study indicated that miR-223 downregulated the IGF-1 receptor and inhibited cell proliferation (10). In addition, the serum IGF-1 level increased in patients with MSA and is associated with disease progression (9).…”

“…Since IGF-1 signaling has been revealed to be regulated by several miRNAs (10,11), it may be hypothesized that miRNAs and IGF-1 contribute to the pathogenesis of MSA.…”

MiRNA-181b suppresses IGF-1R and functions as a tumor suppressor gene in gliomas

“…IGF-1R activates multiple downstream signaling cascades, including PI3K/AKT and MAPK/ERK signaling pathways, which regulate cell proliferation, differentiation, and survival (Baserga et al 2003;Cao et al 2007). More recently, several miRNAs, such as miR-7, miR-145, miR-223, and miR-375, have been reported to negatively regulate IGF-1R (Shi et al 2007;Jia et al 2011;Kong et al 2012;Zhao et al 2012), suggesting that miRNAs targeting IGF-1R have an important role in carcinogenesis and are potential therapeutic agents for human cancer.…”