miR-484 Functions as an Onco-miR in Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer (BC), with a poor prognosis with currently used therapies, and thus represents an unmet therapeutic challenge. Lack of molecular targets (i.e. ER, PR, HER2) and significant genetic heterogeneity are the major reasons contributing to early relapse and high mortality rates. Numerous studies have indicated that microRNAs (miRs) have an important role in BC progression, invasion, angiogenesis, and metastasis. We analyzed miRNA expression profiles of BC patient data bases and identified that miR-484 is highly upregulated in all subtypes of BC patients, with the highest expression in TNBC patients. miR-484 was found to be associated with significantly shorter patient survival, while inhibition of miR-484 in TNBC cells led to significant reduction of cell proliferation, motility and invasion, and induced cell cycle arrest and apoptosis. Furthermore, we found that miR-484 is inversely correlated with levels of HOXA5 in patients’ tumors and demonstrated that miR-484 directly binds to the 3¢-untranslated region (3¢-UTR) of HOXA5 mRNA to suppress its expression. Moreover, HOXA5 over-expression recapitulated the effects of miR-484 inhibition. In vivo therapeutic targeting of miR-484 by systemic administration of anti-miR-484 nanoparticles significantly induced HOXA5 expression and suppressed tumor growth and progression in orthotopic xenograft mouse models of TNBC. Thus, our findings provide new insights about the oncogenic role of miR-484 and suggest that miR-484 represents a novel therapeutic target in TNBC

Dual Suppressive Effect of miR-34a on the FOXM1/eEF2-Kinase Axis Regulates Triple-Negative Breast Cancer Growth and Invasion

Purpose: Recent studies indicated that dysregulation of noncoding KNAs (ncRNA) such as miRNAs is involved in pathogenesis of various human cancers. However, the molecular mechanisms underlying miR-34a are not fully understood in triple-negative breast cancer (TNBC). Experimental Design: We performed in vitro functional assays on TNBC cell lines to investigate the role of mi R-34a in FOLM1/eEF2K signaling axis. TNBC tumor xenograft models were used for in vivo therapeutic delivery of miR-34a. Results: In this study, we investigated the role of p53-driven ncRNA miR-34a and found that miR-34a is associated with significantly longer patient survival in TNBC and inversely correlated with levels of proto-oncogenic eEF2K, which was associated with significantly shorter overall patient survival, We showed that miR-34a directly binds to the 3'-untranslated region of eEF2K and FOXM1 mRNAs and suppresses their expression, leading to inhibition of TNBC cell proliferation, motility, and invasion. Notably, restoring miR-34a expression recapitulated the effects of inhibition of eEF2K and FOXM1, the transcription factor for eEF2K and the direct target of p53, in TNBC cell lines, whereas overexpression of eEF2K and FOXM1 rescued the effects and signaling pathways mediated by miR-34a. Moreover, in vivo therapeutic delivery of miR-34a nanopartides by systemic intravenous administration delayed tumor growth of two different orthotopic TNBC tumor xenograft models by inhibiting eEF2K and FOXM1, intratumoral proliferation and angiogenesis, and inducing apoptosis. Conclusions: Overall, our findings provide new insights into the tumor suppressor role of miR-34a by dual-targeting of FOXM1/eEF2K signaling axis and suggest that miR-34a-based gene therapy may be a potential therapeutic strategy in TNBC. (C)2018 AACR.NIH/NCIUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Cancer Institute (NCI) [R21CA199050, P30CA016672]; noncoding RNA center; NATIONAL CANCER INSTITUTEUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Cancer Institute (NCI) [P30CA016672] Funding Source: NIH RePORTERThis work was supported in part by grants from the NIH/NCI (R21CA199050 and P30CA016672) and the funding from noncoding RNA center and used the Functional Proteomics RPPA Core Facility

The Modulatory Role of MicroRNA-873 in the Progression of KRAS-Driven Cancers

KRAS is one of the most frequently mutated proto-oncogenes in pancreatic ductal adenocarcinoma (PDAC) and aberrantly activated in triple-negative breast cancer (TNBC). A profound role of microRNAs (miRNAs) in the pathogenesis of human cancer is being uncovered, including in cancer therapy. Using in silico prediction algorithms, we identified miR-873 as a potential regulator of KRAS, and we investigated its role in PDAC and TNBC. We found that reduced miR-873 expression is associated with shorter patient survival in both cancers. miR-873 expression is significantly repressed in PDAC and TNBC cell lines and inversely correlated with KRAS levels. We demonstrate that miR-873 directly bound to the 3′ UTR of KRAS mRNA and suppressed its expression. Notably, restoring miR-873 expression induced apoptosis; recapitulated the effects of KRAS inhibition on cell proliferation, colony formation, and invasion; and suppressed the activity of ERK and PI3K/AKT, while overexpression of KRAS rescued the effects mediated by miR-873. Moreover, in vivo delivery of miR-873 nanoparticles inhibited KRAS expression and tumor growth in PDAC and TNBC tumor models. In conclusion, we provide the first evidence that miR-873 acts as a tumor suppressor by targeting KRAS and that miR-873-based gene therapy may be a therapeutic strategy in PDAC and TNBC. Keywords: KRAS, oncogene, non-coding RNA, microRNA, ncRNA, miR-873, proliferation, invasion, gene regulation, tumorigenesis, gene silencing, therapy, nanoparticles, pancreatic cancer, liposomes, breast cancer, triple-negative breast cance