Neurotensin Signaling Activates MicroRNAs-21 and -155 and Akt, Promotes Tumor Growth in Mice, and Is Increased in Human Colon Tumors

Abstract

Background and Aims Neurotensin (NT) promotes colon cancer and inflammation via NT receptor-1 (NTR1). MicroRNAs regulate protein synthesis by targeting mRNAs. We determined the microRNA signature of NTR1 stimulation on human colonic (NCM460) epithelial cells. Methods RNA from NT-stimulated NCM460 cells overexpressing NTR1 was used for microarray expression analysis. NF-κB binding sites were identified by sequence homology, ChIP-assay and qPCR. Tumorigenesis was assessed by the soft agar assay and HCT-116 tumor xenografts in SCID mice. Down-stream targets of NT-regulated microRNAs were identified via bioinformatics, real time PCR and Western blot. Results NT stimulated differential expression of 38 microRNAs. We identified NF-κB binding sites on miR-21 and miR-155, previously implicated in tumor growth. NT increased the number of colonies of HCT-116 cells and antisense-microRNAs against miR-21 and/or miR-155 inhibited this response (p<0.001). NT administration (i.p.) increased the rate of tumor growth in xenograft tumors while miR-21 and/or miR-155 antisense attenuated this response. Since potential downstream targets of miR-21 and miR-155 are PTEN and SOCS1, respectively, and both are upstream of Akt, we investigated the effect of NT on Akt activation. NT activated Akt in HCT-116 cells, an effect inhibited by miR-21 and/or miR-155 antisense (p<0.001). We report for the first time PPP2CA phosphatase as a miR-155 target exerting the effects of NT on Akt. Conclusions NT stimulates miR-21 and miR-155 expression in colonocytes via Akt and NF-κB, and both microRNAs mediate colon tumor growth in response to NT. Importantly, this NT-microRNA circuit is found perturbated in human colon cancers and correlates with tumor stage, suggesting its relevance to human colon carcinogenesis.

NF-κB–driven suppression of FOXO3a contributes to EGFR mutation-independent gefitinib resistance

“…Previous studies reported that TGF-β-mediated Smad4 expression induces miR-155 promoter activity and enriches miR-155 expression to contribute to cell migration and invasion (38), and found that NF-κB, STAT5, or CCAAT/enhancer binding protein beta (C/EBPβ) could bind to miR-155 promoter region and induce miR-155 expression in colon cancer, cutaneous T-cell lymphoma, or fat cells (20,39,40). miR-155 has been considered an "oncomicroRNA" by targeting several tumor suppressors, including SOCS1, FOXO3a, RhoA, C/EBPβ, PP2A/C, and von Hippel-Lindau tumor suppressor (VHL), and it has been found to promote the EMT, invasion, metastasis, growth, and angiogenesis of cancer cells (20,(41)(42)(43). In addition, the up-regulation of miR-155 has been reported to promote tumor angiogenesis by targeting VHL and is associated with poor prognosis for breast cancer (43); additionally, the loss of VHL has been reported to induce NF-κB activity (44).…”

“…5B, Right). In addition, a previous study indicated that NF-κB could bind to a region of the miR-155 promoter (20). To further investigate whether NF-κB is vital for the regulation of miR-155 promoter activity in gefitinib-resistant cells, wild-type or mutant putative NF-κB binding sites of miR-155 promoter were transfected into PC9/WT and PC9/GR cells.…”

Transcriptional activation of the IGF-II/IGF-1R axis and inhibition of IGFBP-3 by miR-155 in hepatocellular carcinoma

“…miR-155 has been demonstrated to be involved in the development of a number of types of malignancies, such as B cell malignancies (8), breast cancer (9) and colon cancer (10), in addition to hepatocellular carcinoma (11), which was the focus of the present study. It has been reported that miR-155 is an oncomiR that is frequently upregulated in HCC (12).…”

NTSR1 (neurotensin receptor 1 (high affinity))

“…NTSR1 activates miR-21 and miR-155, via Akt and NFkB, to down-regulate PTEN and SOCS1 and promote growth of tumors in mice. NTR1, miR-21, and miR-155 levels are increased in human colon tumor samples and correlate with tumor stage (Bakirtzi et al, 2011).…”