Antitumor activity of miR-34a in peritoneal mesothelioma relies on c-MET and AXL inhibition: persistent activation of ERK and AKT signaling as a possible cytoprotective mechanism

Abstract

BackgroundThe value of microRNAs (miRNAs) as novel targets for cancer therapy is now widely recognized. However, no information is currently available on the expression/functional role of miRNAs in diffuse malignant peritoneal mesothelioma (DMPM), a rapidly lethal disease, poorly responsive to conventional treatments, for which the development of new therapeutic strategies is urgently needed. Here, we evaluated the expression and biological effects of miR-34a—one of the most widely deregulated miRNAs in cancer and for which a lipid-formulated mimic is already clinically available—in a large cohort of DMPM clinical samples and a unique collection of in house-developed preclinical models, with the aim to assess the potential of a miR-34a-based approach for disease treatment.MethodsmiR-34a expression was determined by qRT-PCR in 45 DMPM and 7 normal peritoneum specimens as well as in 5 DMPM cell lines. Following transfection with miR-34a mimic, the effects on DMPM cell phenotype, in terms of proliferative potential, apoptotic rate, invasion ability, and cell cycle distribution, were assessed. In addition, three subcutaneous and orthotopic DMPM xenograft models were used to examine the effect of miR-34a on tumorigenicity. The expression of miRNA targets and the activation status of relevant pathways were investigated by western blot.ResultsmiR-34a was found to be down-regulated in DMPM clinical specimens and cell lines compared to normal peritoneal samples. miR-34a reconstitution in DMPM cells significantly inhibited proliferation and tumorigenicity, induced an apoptotic response, and declined invasion ability, mainly through the down-regulation of c-MET and AXL and the interference with the activation of downstream signaling. Interestingly, a persistent activation of ERK1/2 and AKT in miR-34a-reconstituted cells was found to counteract the antiproliferative and proapoptotic effects of miRNA, yet not affecting its anti-invasive activity.ConclusionsOur preclinical data showing impressive inhibitory effects induced by miR-34a on DMPM cell proliferation, invasion, and growth in immunodeficient mice strongly suggest the potential clinical utility of a miR-34a-replacement therapy for the treatment of such a still incurable disease. On the other hand, we provide the first evidence of a potential cytoprotective/resistance mechanism that may arise towards miRNA-based therapies through the persistent activation of RTK downstream signaling.Electronic supplementary materialThe online version of this article (doi:10.1186/s13045-016-0387-6) contains supplementary material, which is available to authorized users.

Circulating microRNA-34 family low expression correlates with poor prognosis in patients with non-small cell lung cancer

“…In terms of NSCLC patients, miR-34 family could regulate platelet-derived growth factor receptor alpha and beta (PDGFR-α and PDGFR-β) to promote tumor necrosis factor ligand superfamily member 10 (TRAIL)-induced apoptosis and reduce invasiveness of lung cancer cells, thereby inhibiting the migratory and invasive capacity of NSCLC cells (15). The results in our study were found that plasma miR34a expression was negatively associated with lymph node metastasis, This might arise from the inhibition of cell proliferation, invasion as well as migration by miR-34a through regulating several pathways (27,(30)(31)(32). Previous study revealed that high miR-34a expression was associated with a lower risk of recurrence or death from breast cancer adjusted by multivariate analysis (33).…”

“…Overexpression of miR-34a could contribute to tumor suppression via repressing human homolog of murine double minute 4 (HDM4) and p53 (30). Upregulated miR-34a expression could inhibit c-MET and AXL by extracellular signal regulated kinase (ERK) and serine/threonine kinase (AKT) signalling activation, suppressing diffuse malignant peritoneal mesothelioma (DMPM) cells proliferation and invasion, thereby resulting in the inhibition of tumorigenesis and tumor growth (31). Also, miR-34a could induce G1 cell cycle arrest, senescence and apoptosis to suppress tumor cells proliferation and promote differentiation, thereby repressing tumor growth and demonstrating the tumorsuppressive role (27); Furthermore, miR-34a overexpression Accumulating OS rate Accumulating OS rate Accumulating OS rate Accumulating OS rate Accumulating OS rate Accumulating OS rate could regulate the Snail1-mediated epithelial-mesenchymal transition (EMT) and the Notch signalling pathway to repress the migration and invasion of pancreatic cancer cells, thereby inhibiting tumor metastasis and pancreatic cancer progression (32).…”

Identification of pAKT as a pharmacodynamic marker for MER kinase in human melanoma G361 cells

“…pAKT is an important biomarker for human cancer [22][23][24][25]. To establish pAKT as a direct phosphorylation target of MER kinase, we developed a MER cellular assay and compared the inhibition of MER activation and AKT phosphorylation.…”

Integrated analysis identifies microRNA-195 as a suppressor of Hippo-YAP pathway in colorectal cancer

“…The 5-year survival rate for localized stage CRC is 90%, whereas as CRC spreads to the regional lymph nodes or distant parts of the body, the 5-year survival rate plunges from 71% to 13% in the United States [2]. These malignancies are ascribed to accumulation of genetic alterations, including dissemination of proto-oncogenes, losing or inactivating of tumor suppressor genes, and EMT, which ultimately lead to tumor evolution and progression [3–7]. …”