Role of MicroRNA 30a Targeting Insulin Receptor Substrate 2 in Colorectal Tumorigenesis

Abstract

d MicroRNAs (miRNAs) are dysregulated in many types of malignant diseases, including colorectal cancer. miRNA 30a (miR-30a) is a member of the miR-30 family and has been implicated in many types of cancers. In this study, we determined the expression of miR-30a in human colon cancer tissues and cell lines. miR-30a was found to be significantly downregulated in both the tissues and cell lines. Furthermore, overexpression of miR-30a inhibited, while silencing of miR-30a promoted, cell proliferation, migration, and invasion in vitro. Consistently, stable overexpression of miR-30a suppressed the growth of colon cancer cell xenografts in vivo. Moreover, bioinformatic algorithms and luciferase reporter assays revealed that insulin receptor substrate 2 (IRS2) is a direct target of miR-30a. Further functional studies suggested that repression of IRS2 by miR-30a partially mediated the tumor suppressor effect of miR-30a. In addition, miR-30a inhibited constitutive phosphorylation of Akt by targeting IRS2. Additionally, clinicopathological analysis indicated that miR-30a has an inverse correlation with the staging in patients with colon cancer. Taken together, our study provides the first evidence that miR-30a suppressed colon cancer cell growth through inhibition of IRS2. Thus, miR-30a might serve as a promising therapeutic strategy for colon cancer treatment. Colorectal cancer (CRC) is the third most common cancer in males and females, with an estimated 142,820 new cases and 50,830 deaths in the United States in 2013. The overall CRC incidence is 5% in the general population, and the 5-year survival rate ranges from 40% to 60% (1). Despite the improvement of currently available treatment strategies, including surgical resection, radiotherapy, and chemotherapy, the survival rate of patients with CRC has changed little over the past 10 years. Almost 50% of CRC patients will die of the disease, mainly due to metastasis to the liver. Thus, it is imperative to achieve earlier diagnosis and better tailoring of treatments to improve CRC outcomes.MicroRNAs (miRNAs) are a family of endogenous small noncoding RNAs that regulate gene expression via the sequence-specific base pairing on the 3= untranslated regions (3= UTRs) of target mRNAs, resulting in mRNA cleavage or translation inhibition (2). More than 30% of the protein-coding genes are controlled by miRNAs, as indicated by bioinformatics predictions. miRNAs are involved in a plethora of biological processes, such as proliferation, migration, invasion, and apoptosis (3, 4). In recent years, miRNAs have been recognized as critical regulators in development and progression of cancer, including CRC (5-8).miRNA 30a (miR-30a) is a member of the miR-30 family, which consists of six distinct mature miRNA sequences: miR-30a/ miR-30c-2, miR-30d/miR-30b, and miR-30e/miR-30c-1 (9). There is considerable evidence suggesting that the dysregulation of miR-30a is correlated with several types of malignant tumors, including breast cancer, lung cancer, thyroid cancer, gastric cancer, and leuke...

Overexpression of miR-30a in lung adenocarcinoma A549 cell line inhibits migration and invasion via targeting <italic>EYA2</italic>

“…These genes include PIK3CD [3], VIM [10], SEPT7 [12], DLL4 [9], CD99 [8], LOX [7], DTL [4], IRS2 [5], FOXL2 [13], etc. In addition, the signaling pathways of miR-30a implicated in the pathogenesis of cancers have also been reported.…”

“…It is clear now that miRNAs perform their biological functions by guiding the RNA-induced silencing complex (RISC) toward 3′ UTR of target mRNAs [2]. miR-30a locates in human chromosome 6q13 and increasing evidence indicates that miR-30a can act as a tumor suppressor to inhibit the growth of various tumors including colorectal carcinoma [3][4][5], breast cancer [6], anaplastic thyroid cancer [7], Ewing's tumor [8], clear cell renal cell carcinoma [9], gastric cancer [10], and nasopharyngeal carcinoma [10,11]. In addition, miR-30a also shows the feature of an oncogene.…”

Downregulation of miR‑30a is associated with proliferation and invasion via targeting MEF2D in cervical cancer

“…miR-30a promotes tumorigenesis in these cancers by directly targeting tumor-associated proteins. Zhang et al (24) demonstrated that miR-30c inhibited the growth and lung metastasis of colon cancer by targeting ADAM metallopeptidase domain 19. miR-30a has also been reported to target insulin receptor substrate 2 in colorectal tumorigenesis (18). However, the expression and role of miR-30a in the progression of cervical cancer remains unclear.…”

“…The cycling conditions for the qPCR were 95˚C for 2 min followed by 45 cycles of 95˚C for 15 sec and 60˚C for 30 sec. The primer sequences for miR-30a and MEF2D were described previously (18,25). miR-30a expression in each sample was calculated by normalizing with U6 and the MEF2D expression in each sample was calculated by normalizing with GAPDH.…”

“…Accumulating evidence indicates that the dysregulation of miR-30a contributes to various malignant tumors, including lung, thyroid, gastric, breast and colon cancer (18)(19)(20)(21)(22)(23). miR-30a promotes tumorigenesis in these cancers by directly targeting tumor-associated proteins.…”