ABSTRACT
BACKGROUND: Nova Circular RNA (circRNA) of non-coding RNA has gradually become an important regulatory factor, and it has made people attach great concern over the occurrence and development of many diseases, particularly carcinomas. circ_RPPH1 is a newly discovered circRNA. Gene Expression Omnibus (GEO) analysis showed that there are high contents of circ_RPPH1 in breast cancer (BC), but the mechanism of circRNA in BC remains unclear. METHODS: Real-time quantitative PCR (qRT-PCR) was applied to test the role of circ_RPPH1 in BC patients, and functional experiments were applied to test the role of circ_RPPH1 on BC tumor. Fluorescence in situ hybridization, double luciferase reporter gene analysis, RNA pull-down and RNA immunoprecipitation experiments were performed to explore the correlation of circ_RPPH1 with miR-146b-3p/E2F2 in BC. RESULTS: circ_RPPH1 was evidently enhanced in BC, and its content was related to the clinical stage and pathological grade. circ_RPPH1 can accelerate the proliferation, migration and invasion, and promote tumorigenesis and metastasis. Mechanism exploration indicated that circ_RPPH1 acted as ceRNA (competing endogenous RNA) of miR-146b-3p, so as to reduce the inhibitory role of miR-146b-3p on its target E2F2. CONCLUSION: Circ_RPPH1/miR-146b-3p/E2F2 axis can promote the progression of BC, and it might be a latent therapeutic target for clinical BC.
Subject(s)
Breast Neoplasms/genetics , Breast Neoplasms/physiopathology , Carcinoma/genetics , E2F2 Transcription Factor/genetics , MicroRNAs/genetics , RNA, Circular/genetics , Animals , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Carcinoma/metabolism , Carcinoma/pathology , Carcinoma/physiopathology , Cell Line, Tumor , Cell Proliferation , E2F2 Transcription Factor/metabolism , Female , Gene Expression Regulation, Neoplastic , Humans , Mice, Inbred BALB C , MicroRNAs/metabolism , Neoplasm Metastasis , RNA, Circular/metabolismABSTRACT
OBJECTIVE: Deoxyribonucleoside kinase of Drosophila melanogaster (Dm-dNK) mutants have been reported to exert suicide gene effects in combined gene/chemotherapy of cancer. Here, we aimed to further evaluate the capacity of the mutanted enzyme and its potential for inhibiting cancer cell growth. METHODS: We altered the sequence of the last 10 amino acids of Dm-dNK to perform site-directed mutagenesis and constructed active site mutanted Dm-dNK (Dm-dNKmut), RT-PCR and western bloting studies were used to reveal the expression of lentivirus mediated Dm-dNKmut in a breast cancer cell line (Bcap37), a gastric cancer cell line (SGC7901) and a colorectal cancer cell line (CCL187). [3H]-labeled substrates were used for enzyme activity assays, cell cytotoxicity was assessed by MTT assays, cell proliferation using a hemocytometer and apoptosis induction by thenannexin-V-FITC labeled FACS method. In vivo, an animal study was set out in which BALB/C nude mice bearing tumors were treated with lentivirus mediated expression of Dm-dNKmut with the pyrimidine nucleoside analog brivudine (BVDU, (E)-5-(2-bromovinyl)-(2-deoxyuridine). RESULTS: The Dm-dNKmut could be stably expressed in the cancer cell lines and retained its enzymatic activity. Moreover, the cells expressing Dm-dNKmut exhibited increased sensitivity in combination with BVDU, with induction of apoptosis in vitro and in vivo. CONCLUSION: These findings underlined the importance of BVDU phosphorylated by Dm-dNKmut in transduced cancer cells and the potential role of Dm-dNKmut as a suicide gene, thus providing the basis for future intensive research for cancer therapy.
