Recent studies have focused on molecular factors, which serve a function in carcinoma development. Thus, as a prospective consequence, novel treatment strategies targeting these factors and their receptors have been improved. The IGF signaling axis is among the major target themes of many studies searching for new strategies in tumor treatment. The IGF signaling axis comprises three growth factors (IGF-1, IGF-2, and insulin), three membrane receptors (IGF-1R, IGF-2R, and IR), six circulating IGF-binding proteins (IGFBP1 to IGFBP6), and proteases that modulate ligand availability [
23],[
24]. IGF-1R serves many important functions in various pathways of mitogenesis, angiogenesis, transformation, apoptosis, and cell motility [
25]. IGF-1Rs also interfere with mitogenic and antiapoptotic events in malignant cells. Thus, IGF-1R serves a potential function in carcinogenesis. Activated phosphorylated IGF-1R recruits and activates signaling adaptor proteins, including IRS-I, IRS-2, and Shc [
26]. IRS phosphorylation activates the phosphoinositide-3-kinase/Akt pathway, thereby resulting in the synthesis of membrane-associated phosphatidylinositol (3, 4, 5)-trisphosphate. Consequently, Akt and protein kinase B are activated. Akt is a kinase-activating molecule that induces antiapoptotic proteins [
27]. As a result of this signaling, many IGF-1R effects are mediated, including mitogenesis, proliferation, cell-cycle control, and inhibition of apoptosis [
28]. We examined the mechanisms underlying the loss of IGF-1R-inhibited cellular growth and metabolism through the Akt pathway in glioma cells. Downregulation of IGF-1R inhibited the activity of Akt and suppressed cellular growth and metabolism.
Dysregulation of miRNA sequences is a common feature in human cancers, including glioma. miRNA is a small non-coding single-stranded RNA comprising 21 nucleotides to 25 nucleotides and regulates the expression of target genes by interacting with specific sites on messenger RNA, thereby repressing protein translation. miRNA sequences have important regulatory functions in basic biological processes, such as development, cellular differentiation, proliferation, and apoptosis. Altered miRNA regulation is involved in glioma pathogenesis via oncogene and tumor suppressor modulation, which subsequently affects downstream signaling pathways [
29]-[
31]. Consistent with previous reports, miR-7 was downregulated in human glioma tissues in the current study [
17]. Upregulation of miR-7 inhibited cellular growth and glucose metabolism. Bioinformatics analysis results indicated that IGF-1R could be a target of miR-7. Western blot and luciferase reporter assays showed that miR-7 modulated IGF-1R expression by directly targeting the binding site within the 3'-UTR.