MicroRNA-494 Downregulates KIT and Inhibits Gastrointestinal Stromal Tumor Cell Proliferation

Abstract

Purpose: Gain-of-function mutations and KIT overexpression are well-known tumorigenesis mechanisms in gastrointestinal stromal tumors (GIST). This study aimed to discover microRNAs (miRNA) that target KIT and reveal the relationship between the discovered miRNAs and KIT expression in GISTs.Experimental Design: Fresh-frozen GISTs from 31 patients were used to confirm the relationship between miR-494 and KIT expression using quantitative reverse transcription-PCR to assess miR-494 expression levels and Western blotting to assess KIT protein expression levels. A luciferase assay was conducted for the target evaluation. The functional effects of miR-494 on GIST882 cells (GIST cell line with activating KIT mutation) were validated by a cell proliferation assay and fluoresce-activated cell sorting analysis.Results: An inverse relationship was found between the expression levels of miR-494 and KIT in GISTs (r ¼ À0.490, P ¼ 0.005). The direct targeting of KIT by miR-494 was shown by the reduction in KIT expression after miR-494 overexpression and the increase in KIT expression after inhibiting endogenous miR-494 expression. We showed that miR-494 regulates KIT by binding two different seed match sites. Induced miR-494 overexpression in GIST882 reduced the expression of downstream molecules in KIT signaling transduction pathways, including phospho-AKT and phospho-STAT3. Finally, miR-494 overexpression provoked apoptosis and inhibited GIST cell growth, which were accompanied by changes in G 1 and S phase content.Conclusion: Our findings indicate that miR-494 is a negative regulator of KIT in GISTs and overexpressing miR-494 in GISTs may be a promising approach to GIST treatment.

MiR-494 is regulated by ERK1/2 and modulates TRAIL-induced apoptosis in non–small-cell lung cancer through BIM down-regulation

“…We identified several miRNAs down-regulated after the PED S104G overexpression and, among these, we focused on miR-494 because it exhibited the highest fold change. MiR-494 is known as an oncomir in gastrointestinal stromal tumors targeting the proto-oncogene KIT (28). In addition, miR-494 enhances myocyte survival by targeting PTEN, ROCK1, and CAMKIId and protects against ischemia/reperfusion-induced cardiac injury (29).…”

MicroRNA-494 Reduces ATF3 Expression and Promotes AKI

“…8 In addition, miR-494 has been reported to promote cancer cell death. 10,21 These findings suggest that miR-494 exhibits differential effects on divergent targets to balance a common signaling pathway and eventually, determine the expression phenotype. Regardless, miR-494 is abundantly expressed in a variety of organs, such as the brain, heart, liver, and kidneys ( Figure 2).…”

“…9 As for the physiologic functions of miR-494, almost all focus has been on cancer research. 10,11 In the heart, experiments with transgenic mice overexpressing cardiac-specific miR-494 showed that elevation of miR-494 improved the post-I/R recovery of cardiac function and suppressed I/R-triggered cardiomyocyte apoptosis and necrosis. 8 However, whether miR-494 plays an important role in the regulation of renal I/R injury is unknown.…”

Correlation of miR-494 expression with tumor progression and patient survival in pancreatic cancer

“…Furthermore, Romano et al (2012) found that miR-494 was regulated by ERK1/2 and modulated by tumor necrosis factorrelated apoptosis-inducing ligand-induced apoptosis in non-small-cell lung cancer through BIM downregulation. The findings by Kim et al (2011) indicated that miR-494 was a negative regulator of KIT in gastrointestinal stromal tumors (GISTs), and overexpressing miR-494 in GISTs might be a promising approach to GIST treatment. Previously, Li et al found that downregulation of miR-494 via the loss of SMAD4 increased FOXM1 and β-catenin signaling in pancreatic cancer cells.…”