miR-603 promotes cell proliferation and differentiation by targeting TrkB in acute promyelocytic leukemia.

Arsenic trioxide (ATO) treatment effectively prolongs the overall survival of patients with acute promyelocytic leukemia (APL). Mutations in the oncogene PML::RARA were found in patients with ATO-resistant and relapsed APL. However, some relapsed patients do not have such mutations. Here, we performed microarray analysis of samples from newly diagnosed and relapsed APL, and found different microRNA (miRNA) expression patterns between these two groups. Among the differentially expressed miRNAs, miR-603 was expressed at the lowest level in relapsed patients. The expression of miR-603 and its predicted target tropomyosin-related kinase B (TrkB) were determined by PCR and Western blot. Proliferation was measured using an MTT assay, while apoptosis, cell cycle and CD11b expression were analyzed using flow cytometry. In APL patients, the expression of miR-603 was negatively correlated with that of TrkB. miR-603 directly targeted TrkB and downregulated TrkB expression in the APL cell line NB4. miR-603 increased cell proliferation by promoting the differentiation and inhibiting the apoptosis of NB4 cells. This study shows that the miR-603/ TrkB axis may be a potent therapeutic target for relapsed APL.

Circular RNA circ_IRAK3 contributes to tumor growth through upregulating KIF2A via adsorbing miR-603 in breast cancer.

BACKGROUND: Breast cancer (BC) threatens the health of women around the world. Researchers have proved that hsa_circ_0005505 (circ_IRAK3) facilitates BC cell invasion and migration, but the regulatory mechanisms of circ_IRAK3 in BC remain mostly unknown. We aim to explore a new mechanism by which circ_IRAK3 promotes BC progression. METHODS: Levels of circ_IRAK3, microRNA (miR)-603, and kinesin family member 2A (KIF2A) mRNA in BC tissues and cells were examined by quantitative real-time polymerase chain reaction (qRT-PCR). The cell cycle progression, colony formation, and proliferation of BC cells were evaluated by flow cytometry, plate clone, or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assays. The migration, invasion, and apoptosis of BC cells were determined by transwell or flow cytometry assays. Several protein levels were detected using western blotting. The targeting relationship between circ_IRAK3 or KIF2A and miR-603 was verified via dual-luciferase reporter assay. The role of circ_IRAK3 in vivo was verified by xenograft assay. RESULTS: We observed higher levels of circ_IRAK3 in BC tissues and cell lines than their respective controls. Functional experiments presented that circ_IRAK3 silencing induced BC cell apoptosis, curbed cell proliferation, migration, and invasion in vitro, and decreased tumor growth in vivo. Mechanistically, circ_IRAK3 could modulate kinesin family member 2A (KIF2A) expression through acting as a microRNA (miR)-603 sponge. miR-603 silencing impaired the effects of circ_IRAK3 inhibition on the malignant behaviors of BC cells. Also, the repressive effects of miR-603 mimic on the malignant behaviors of BC cells were weakened by KIF2A overexpression. CONCLUSIONS: circ_IRAK3 exerted a promoting effect on BC progression by modulating the miR-603/KIF2A axis, providing a piece of novel evidence for circ_IRAK3 as a therapeutic target for BC.

Association of MAPK and its regulatory miRNAs (603, 4301, 8485, and 4731) with the malignant transformation of oral lichen planus.

Oral lichen planus (OLP) is a potentially malignant oral lesion that may transform into oral squamous cell carcinoma (OSCC). The purpose of this study was to assess the level of expression of MAPK/ERK1/2 gene, and microRNA (miR)-603, 4301, 8485, and 4731 in the MAPK signaling pathway in OLP and OSCC lesions. This case-control study evaluated 26 OSCC, 20 OLP and 20 healthy control tissue specimens. After RNA extraction, the respective miRNA and MAPK/ERK1/2 mRNA levels were assessed by quantitative reverse transcription polymerase chain reaction (RT-PCR). Significant upregulation of MAPK/ERK1/2 gene was noted in the OLP and OSCC specimens compared with healthy controls (p < 0.001). The expression level of miR-4731 was significantly lower in the OLP and OSCC specimens than in the healthy specimens (p < 0.001). The expression of MiR-603 was the lowest in OLP, followed by OSCC and then the control group (p < 0.001). No significant difference was found in miR-4801 levels between OSCC and OLP specimens compared with healthy controls (p = 0.43 and p = 0.86, respectively). In addition, a non-significant decrease in miR-8485 levels was noted in the OSCC and OLP specimens compared with healthy controls (p = 0.98 and p = 0.61, respectively). A significant decrease in level of miR-603 was noted in OLP compared with OSCC group (p < 0.001). The miR-4801 and miR-8485 expression levels were directly correlated with MAPK/ERK1/2 mRNA expression (p = 0.01). Higher expression level of MAPK/ERK1/2, miR-603, miR-4801, and miR-4731, and lower expression level of miR-8485 were correlated with significantly lower overall survival rate in OSCC patients. The increased expression of MAPK/ERK1/2 and decreased expression of miR-603 and miR-4731 are associated with greater risk of OLP malignant transformation and poor histopathological characteristics of OSCC.

Thymoquinone inhibits cell proliferation, migration, and invasion by regulating the elongation factor 2 kinase (eEF-2K) signaling axis in triple-negative breast cancer.

BACKGROUND/PURPOSE: Triple-negative breast cancer (TNBC) is the most aggressive and chemoresistant subtype of breast cancer. Therefore, new molecular targets and treatments need to be developed to improve poor patient prognosis and survival. We have previously shown that eukaryotic elongation factor 2 kinase (eEF-2K) is highly expressed in TNBC cells, is associated with poor patient survival and prognosis, and promotes cell proliferation, migration, and invasion. In vivo targeting of eEF-2K significantly reduces the tumor growth of orthotopic TNBC xenograft mouse models, suggesting that eEF-2K may serve as a potential novel therapeutic target. METHODS/RESULTS: In the current study, we identified thymoquinone (TQ), an active ingredient of Nigella sativa, as a potential safe and effective eEF-2K inhibitor in TNBC. We demonstrated for the first time that TQ inhibits the protein and mRNA expression of eEF-2K, as well as the clinically relevant downstream targets, including Src/FAK and Akt, and induces the tumor suppressor miR-603, in response to NF-kB inhibition. This effect was associated with a significant decrease in the proliferation, colony formation, migration, and invasion of TNBC cells. Furthermore, systemic in vivo injection of TQ (20 and 100 mg/kg) significantly reduced the growth of MDA-MB-231 tumors and inhibited the eEF-2K expression in an orthotopic tumor model in mice. CONCLUSION: Our study provides first evidence that TQ treatment inhibits cell proliferation, migration/invasion, and tumor growth, in part through the inhibition of eEF-2K signaling in TNBC. Thus, our findings suggest that systemic TQ treatment may be used as a targeted therapeutic strategy for the inhibition of eEF-2K in TNBC tumor growth and progression.

Targeted Liposomes Encapsulating miR-603 Complexes Enhance Radiation Sensitivity of Patient-Derived Glioblastoma Stem-Like Cells.

Despite potential for clinical efficacy, therapeutic delivery of microRNAs (miRNA) remains a major translational barrier. Here, we explore a strategy for miRNA delivery in the treatment of glioblastoma, the most common form of adult brain cancer, that involves complexation of miRNA with polyethylenimine (PEI) and encapsulation in targeted liposomes. miRNA 603 (miR-603) is a master regulatory miRNA that suppresses glioblastoma radiation resistance through down-regulation of insulin-like growth factor 1 (IGF1) signaling. miR-603 was complexed with PEI, a cationic polymer, and encapsulated into liposomes decorated with polyethylene glycol (PEG) and PR_b, a fibronectin-mimetic peptide that specifically targets the α5ß1 integrin that is overexpressed in glioblastomas. Cultured patient-derived glioblastoma cells internalized PR_b-functionalized liposomes but not the non-targeted liposomes. The integrin targeting and complexation of the miRNA with PEI were associated with a 22-fold increase in intracellular miR-603 levels, and corresponding decreases in IGF1 and IGF1 receptor (IGF1R) mRNA expression. Moreover, treatment of glioblastoma cells with the PR_b liposomes encapsulating miR-603/PEI sensitized the cells to ionizing radiation (IR), a standard of care treatment for glioblastomas. These results suggest that PR_b-functionalized PEGylated liposomes encapsulating miR-603/PEI complexes hold promise as a therapeutic platform for glioblastomas.

Radiation-induced extracellular vesicle (EV) release of miR-603 promotes IGF1-mediated stem cell state in glioblastomas.

BACKGROUND: Recurrence after radiation therapy is nearly universal for glioblastomas, the most common form of adult brain cancer. The study aims to define clinically pertinent mechanisms underlying this recurrence. METHODS: microRNA (miRNA) profiling was performed using matched pre- and post-radiation treatment glioblastoma specimens from the same patients. All specimens harbored unmethylated O6-methylguanine-DNA methyltransferase promoters (umMGMT) and wild-type isocitrate dehydrogenase (wtIDH). The most altered miRNA, miR-603, was characterized. FINDINGS: While nearly all miRNAs remained unchanged after treatment, decreased levels of few, select miRNAs in the post-treatment specimens were observed, the most notable of which involved miR-603. Unbiased profiling of miR-603 targets revealed insulin-like growth factor 1 (IGF1) and IGF1 receptor (IGF1R). Ionizing radiation (IR) induced cellular export of miR-603 through extracellular vesicle (EV) release, thereby de-repressing IGF1 and IGF1R. This de-repression, in turn, promoted cancer stem-cell (CSC) state and acquired radiation resistance in glioblastomas. Export of miR-603 additionally de-repressed MGMT, a DNA repair protein responsible for detoxifying DNA alkylating agents, to promote cross-resistance to these agents. Ectopic miR-603 expression overwhelmed cellular capacity for miR-603 export and synergized with the tumoricidal effects of IR and DNA alkylating agents. INTERPRETATION: Profiling of matched pre- and post-treatment glioblastoma specimens revealed altered homeostasis of select miRNAs in response to radiation. Radiation-induced EV export of miR-603 simultaneously promoted the CSC state and up-regulated DNA repair to promote acquired resistance. These effects were abolished by exogenous miR-603 expression, suggesting potential for clinical translation. FUNDING: NIH 1R01NS097649-01, 9R44GM128223-02, 1R01CA240953-01, the Doris Duke Charitable Foundation Clinical Scientist Development Award, The Sontag Foundation Distinguished Scientist Award, the Kimmel Scholar Award, and BWF 1006774.01 (C.C.C).

MicroRNA 603 acts as a tumor suppressor and inhibits triple-negative breast cancer tumorigenesis by targeting elongation factor 2 kinase.

Triple negative breast cancer (TNBC) is an aggressive type of breast cancer characterized by the absence of defined molecular targets, including estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and is associated with high rates of relapse and distant metastasis despite surgery and adjuvant chemotherapy. The lack of effective targeted therapies for TNBC represents an unmet therapeutic challenge. Eukaryotic elongation factor 2 kinase (eEF2K) is an atypical calcium/calmodulin-dependent serine/threonine kinase that promotes TNBC tumorigenesis, progression, and drug resistance, representing a potential novel molecular target. However, the mechanisms regulating eEF2K expression are unknown. Here, we report that eEF2K protein expression is highly up-regulated in TNBC cells and patient tumors and it is associated with poor patient survival and clinical outcome. We found that loss/reduced expression of miR-603 leads to eEF2K overexpression in TNBC cell lines. Its expression results in inhibition of eEF2K by directly targeting the 3-UTR and the inhibition of tumor cell growth, migration and invasion in TNBC. In vivo therapeutic gene delivery of miR-603 into TNBC xenograft mouse models by systemic administration of miR-603-nanoparticles led to a significant inhibition of eEF2K expression and tumor growth, which was associated with decreased activity of the downstream targets of eEF2K, including Src, Akt, cyclin D1 and c-myc. Our findings suggest that miR-603 functions as a tumor suppressor and loss of miR-603 expression leads to increase in eEF2K expression and contributes to the growth, invasion, and progression of TNBC. Taken together, our data suggest that miR-603-based gene therapy is a potential strategy against TNBC.

Primate-specific miR-603 is implicated in the risk and pathogenesis of Alzheimer's disease.

Alzheimer's disease (AD) is a serious neurodegenerative disease, and microRNAs (miRNAs) have been linked to its pathogenesis. miR-603, a novel primate-specific miRNA and an intronic miRNA of a human brain highly expressed gene KIAA1217, is implicated in the risk and pathogenesis of AD. The rs11014002 single nucleotide polymorphism (SNP) (C/U), which locates in miR-603 precursor (pre-miR-603), exhibits a protective effect towards AD risk. Additionally, the rs11014002 SNP promotes the biogenesis of mature miR-603. miR-603 downregulates LRPAP1 mRNA and protein levels through directly binding the 3' untranslated region (3'UTR) of LRPAP1. Moreover, miR-603 increases LRP1 protein expression. LRPAP1 and LRP1, playing opposite roles, are involved in Aß clearance and pathogenesis of AD. Strikingly, miR-603 exhibits a relatively higher expression and there is a loss of a negative correlation between miR-603 and LRPAP1/RND1 mRNA levels in the hippocampi of patients with AD. In addition, miR-603 directly downregulates a key neuronal apoptotic component-E2F1, and prevents HeLa cells from undergoing H2O2-induced apoptosis. This work suggests that miR-603 may be a novel AD-relevant miRNA and that its rs11014002 SNP may serve as a protective factor against AD.

miR-603 promotes glioma cell growth via Wnt/ß-catenin pathway by inhibiting WIF1 and CTNNBIP1.

Gliomas are the most common and deadly type of brain tumor. In spite of progressive treatments, patient prognosis has not improved significantly. MicroRNAs are considered promising candidates for glioma therapy. MiR-603 was found overexpressed in both glioma tissues and cell lines. MiR-603 promoted cell proliferation, cell cycle progression and neurosphere formation. Conversely, inhibition of miR-603 remarkably reduced these effects. We confirmed that WIF1 and CTNNBIP1 are bona fide targets of miR-603. The negative correlation between miR-603 and these molecules' expression was shown by Pearson correlation in 50 primary glioma tissue samples. Furthermore, overexpression of miR-603 promoted nuclear ß-catenin levels and TOPflash luciferase activity, indicating that miR-603 activates the Wnt/ß-catenin signaling pathway. Our in vivo results confirmed the positive role of miR-603 in glioma development. We demonstrate that miR-603 regulates glioma development via its WIF1 and CTNNBIP1 targets, which suggests that miR-603 may be a promising candidate for therapeutic applications in glioma treatment.

Associations between hsa-miR-603 polymorphism, lifestyle-related factors and colorectal cancer risk.

BACKGROUND: Accumulated studies have suggested that single nucleotide polymorphisms (SNPs) in microRNAs are associated with risk of colorectal cancer (CRC). OBJECTIVE: We tested our hypothesis that rs11014002 in hsa-miR-603 may be associated with CRC risk with a crosstalk of life-related factors. METHODS: We conducted a case-control study which included 102 CRC patients and 204 matched cancer-free controls in Xiaoshan County. RESULTS: We observed that subjects with rs11014002 CT/TT genotype had an increased susceptibility for CRC (CT vs. CC: odds ratio (OR)=2.352, 95% confidence interval (CI): 1.142-4.840, P=0.020; CT+TT vs. CC: OR=2.031, 95% CI: 1.063-3.883, P=0.032). After stratification by lifestyle-related factors, similar results were found among nonsmokers (CT vs. CC: OR=2.753, 95% CI: 1.085-6.983, P=0.033; CT+TT vs. CC: OR=2.971, 95% CI: 1.188-7.435, P=0.020) and non-alcohol drinkers (CT+TT vs. CC: OR=3.279, 95% CI: 1.071-10.033, P=0.037). CONCLUSIONS: Our data suggest that hsa-miR-603 may be involved in colorectal tumorigenesis, and the genetic polymorphism in hsa-miR-603 is associated with CRC susceptibility.