miR-34a and miR-15a/16 are co-regulated in non-small cell lung cancer and control cell cycle progression in a synergistic and Rb-dependent manner

Abstract

BackgroundmicroRNAs (miRNAs) are small non-coding RNAs that are frequently involved in carcinogenesis. Although many miRNAs form part of integrated networks, little information is available how they interact with each other to control cellular processes. miR-34a and miR-15a/16 are functionally related; they share common targets and control similar processes including G1-S cell cycle progression and apoptosis. The aim of this study was to investigate the combined action of miR-34a and miR-15a/16 in non-small cell lung cancer (NSCLC) cells.MethodsNSCLC cells were transfected with miR-34a and miR-15a/16 mimics and analysed for cell cycle arrest and apoptosis by flow cytometry. Expression of retinoblastoma and cyclin E1 was manipulated to investigate the role of these proteins in miRNA-induced cell cycle arrest. Expression of miRNA targets was assessed by real-time PCR. To investigate if both miRNAs are co-regulated in NSCLC cells, tumour tissue and matched normal lung tissue from 23 patients were collected by laser capture microdissection and compared for the expression of these miRNAs by real-time PCR.ResultsIn the present study, we demonstrate that miR-34a and miR-15a/16 act synergistically to induce cell cycle arrest in a Rb-dependent manner. In contrast, no synergistic effect of these miRNAs was observed for apoptosis. The synergistic action on cell cycle arrest was not due to a more efficient down-regulation of targets common to both miRNAs. However, the synergistic effect was abrogated in cells in which cyclin E1, a target unique to miR-15a/16, was silenced by RNA interference. Thus, the synergistic effect was due to the fact that in concerted action both miRNAs are able to down-regulate more targets involved in cell cycle control than each miRNA alone. Both miRNAs were significantly co-regulated in adenocarcinomas of the lung suggesting a functional link between these miRNAs.ConclusionsIn concerted action miRNAs are able to potentiate their impact on G1-S progression. Thus the combination of miRNAs of the same network rather than individual miRNAs should be considered for assessing a biological response. Since miR-34a and miR-15a/16 are frequently down-regulated in the same tumour tissue, administrating a combination of both miRNAs may also potentiate their therapeutic impact.

Large-scale screening identifies a novel microRNA, miR-15a-3p, which induces apoptosis in human cancer cell lines

“…In addition, the ectopic miR-15a-5p and miR-16, were able to inhibit growth and induce apoptosis in some tumors with high Bcl-2 expression levels. 6,[61][62][63] The present findings broaden the role of the miR-15a/16 cluster to activate apoptosis cascade in Bcl-x L -overexpressing tumors by miR-15a-3p. These findings extend the potential of this miRNA cluster as a tumor suppressor in cancer-related miRNAs therapies.…”

The effects of lanthanum chloride on proliferation and apoptosis of cervical cancer cells: involvement of let-7a and miR-34a microRNAs

“…miR-34 family mediates such functions through additive or synergistic effects on multiple targets, including cyclin-dependent kinase 4 (CDK4), CDK6, E2F3, cyclin D1, cyclin E2, Bcl-2, and others (Antonini et al 2010;Bommer et al 2007;Sun et al 2008). Reportedly, miR-34a is able to down-regulate the antiapoptosis protein Bcl-2 in non-small cell lung cancer and induce apoptosis by activating apoptotic protein caspase-3 in pancreatic cancer stem cells (CSCs) (Bandi and Vassella 2011;Nalls et al 2011). Our data revealed that lanthanum chloride induced a significant increase of mir-34a and a decrease in Bcl-2 and Cyclin D1 levels, finally resulted in cell cycle arrest at G1 phase.…”

Regression of A549 lung cancer tumors by anti-miR-150 vector

“…miR-155 and miR-21) (5). Indeed, several miRNAs are reported to have important roles in different types of cancer, including acute myelogenous leukemia (6,7), chronic myelogenous leukemia (CML) (8)(9)(10), lung cancer (11,12), and breast cancer (13), among others. miRNAs have also been shown to play a role in cancer progression through the modulation of cellular adhesion, cell matrix and signaling activities (14,15).…”