MicroRNA expression abnormalities in pancreatic endocrine and acinar tumors are associated with distinctive pathologic features and clinical behavior
ABSTRACT We investigated the global microRNA expression patterns in normal pancreas, pancreatic endocrine tumors and acinar carcinomas to evaluate their involvement in transformation and malignant progression of these tumor types. MicroRNAs are small noncoding RNAs that regulate gene expression by targeting specific mRNAs for degradation or translation inhibition. Recent evidence indicates that microRNAs can contribute to tumor development and progression and may have diagnostic and prognostic value in several human malignancies.
Using a custom microarray, we studied the global microRNA expression in 12 nontumor pancreas and 44 pancreatic primary tumors, including 12 insulinomas, 28 nonfunctioning endocrine tumors, and four acinar carcinomas.
Our data showed that a common pattern of microRNA expression distinguishes any tumor type from normal pancreas, suggesting that this set of microRNAs might be involved in pancreatic tumorigenesis; the expression of miR-103 and miR-107, associated with lack of expression of miR-155, discriminates tumors from normal; a set of 10 microRNAs distinguishes endocrine from acinar tumors and is possibly associated with either normal endocrine differentiation or endocrine tumorigenesis; miR-204 is primarily expressed in insulinomas and correlates with immunohistochemical expression of insulin; and the overexpression of miR-21 is strongly associated with both a high Ki67 proliferation index and presence of liver metastasis.
These results suggest that alteration in microRNA expression is related to endocrine and acinar neoplastic transformation and progression of malignancy, and might prove useful in distinguishing tumors with different clinical behavior.
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ABSTRACT: Several previous reports indicated that microRNA-504 (miR-504) has an oncogenic function through negatively regulating p53. On the other hand, a recent study revealed that miR-504 inhibits cancer cell proliferation through targeting CDK6 in hypopharyngeal squamous cell carcinoma (HSCC), suggesting the tumor suppressive role of this miRNA. However, the role of miR-504 in human malignant glioma remains unclear. Therefore, the aim of this study was to investigate the clinical significance of miR-504 expression in high pathological grade glioma. Quantitative real-time reverse transcriptive-PCR (qRT-PCR) was performed to examine miR-504 expression levels in 63 glioma tissues including 13 anaplastic astrocytomas (AA, WHO grade III) and 50 glioblastomas (GBM, WHO grade IV), as well as 10 non-neoplastic brain tissues. Associations between miR-504 expression and clinicopathological factors and prognosis of glioma patients were statistically analyzed. MiR-504 showed significant decreased expression levels both in AAs and GBMs relative to non-neoplastic brains (P ≤ 0.001, respectively). Additionally, low expression level of miR-504 was significantly associated with advanced WHO grade (P = 0.01). Moreover, Kaplan-Meier survival analysis showed that patients with low expression of miR-504 had significantly poor survival rate (P = 0.002). Cox regression analysis showed that miR-504 expression was independent prognosis-predicting factor for malignant glioma patients (P = 0.038; risk ration = 2.5). Our results suggest that miR-504 may be a prognostic predictor and be involved in tumorigencity as a tumor suppressor of malignant glioma.
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ABSTRACT: Aberrant expression of microRNAs (miRNAs) was reported frequently in different human cancers. The major role of miRNA is targeting 3′-UTR of coding gene and causing translational repression or mRNA degradation. miR-10b overexpression was reported to promote breast cancer metastasis by up-regulating RHOC expression. But its expression in hepatocellular carcinoma (HCC) remains unclear. Our study indicated that the expression of miR-10b was different in HCC and adjacent tissue samples, and reduced expression of miR-10b in HCC was related to vein invasion. High-level expression of RHOC was also related to vein invasion in HCC. But no correlation was found between miR-10b and RHOC expression. These results suggest that miR-10b and RHOC are independent predictors of HCC invasion and metastasis.Chinese Science Bulletin 07/2014; 59(19):2249-2253. DOI:10.1007/s11434-014-0271-0 · 1.37 Impact Factor
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ABSTRACT: MicroRNAs (miRNAs) have been implicated in the development of some if not all cancer types and have been identified as attractive targets for prognosis, diagnosis, and therapy of the disease. miRNAs are a class of small non-coding RNAs (20-22 nt in length) that bind imperfectly to the 3'-untranslated region of target mRNA regulating gene expression. Aberrantly expressed miRNAs in cancer, sometimes known as oncomiRNAs, have been shown to play a major role in oncogenesis, metastasis, and drug resistance. Amplification of oncomiRNAs during cancer development correlates with the silencing of tumor suppressor genes; on the other hand, down-regulation of miRNAs has also been observed in cancer and cancer stem cells (CSCs). In both cases, miRNA regulation is inversely correlated with cancer progression. Growing evidence indicates that miRNAs are also involved in the metastatic process by either suppressing or promoting metastasis-related genes leading to the reduction or activation of cancer cell migration and invasion processes. In particular, circulating miRNAs (vesicle-encapsulated or non-encapsulated) have significant effects on tumorigenesis: membrane-particles, apoptotic bodies, and exosomes have been described as providers of a cell-to-cell communication system transporting oncogenic miRNAs from tumors to neighboring cells and distant metastatic sites. It is hypothesized that miRNAs control cancer development in a traditional manner, by regulating signaling pathways and factors. In addition, recent developments indicate a non-conventional mechanism of cancer regulation by stem cell reprograming via a regulatory network consisting of miRNAs and Wnt/β-catenin, Notch, and Hedgehog signaling pathways, all of which are involved in controlling stem cell functions of CSCs. In this review, we focus on the role of miRNAs in the Notch-pathway and how they regulate CSC self-renewal, differentiation and tumorigenesis by direct/indirect targeting of the Notch-pathway.Frontiers in Oncology 01/2014; 4:389. DOI:10.3389/fonc.2014.00389