ABSTRACT
Epigenetic silencing through methylation is one of the major mechanisms for downregulation of tumor suppressor miRNAs in various malignancies. The aim of this study was to identify novel tumor suppressor miRNAs which are silenced by DNA hypermethylation and investigate the role of at least one of these in oral squamous cell carcinoma (OSCC) pathogenesis. We treated cells from an OSCC cell line SCC131 with 5-Azacytidine, a DNA methyltransferase inhibitor, to reactivate tumor suppressor miRNA genes silenced/downregulated due to DNA methylation. At 5-day post-treatment, total RNA was isolated from the 5-Azacytidine and vehicle control-treated cells. The expression of 2,459 mature miRNAs was analysed between 5-Azacytidine and control-treated OSCC cells by the microRNA microarray analysis. Of the 50 miRNAs which were found to be upregulated following 5-Azacytidine treatment, we decided to work with miR-6741-3p in details for further analysis, as it showed a mean fold expression of >4.0. The results of qRT-PCR, Western blotting, and dual-luciferase reporter assay indicated that miR-6741-3p directly targets the oncogene SRSF3 at the translational level only. The tumor-suppressive role of miR-6741-3p was established by various in vitro assays and in vivo study in NU/J athymic nude mice. Our results revealed that miR-6741-3p plays a tumor-suppressive role in OSCC pathogenesis, in part, by directly regulating SRSF3. Based on our observations, we propose that miR-6741-3p may serve as a potential biological target in tumor diagnostics, prognostic evaluation, and treatment of OSCC and perhaps other malignancies.
Subject(s)
Carcinoma, Squamous Cell , Gene Expression Regulation, Neoplastic , MicroRNAs , Mouth Neoplasms , Serine-Arginine Splicing Factors , MicroRNAs/genetics , MicroRNAs/metabolism , Humans , Mouth Neoplasms/genetics , Mouth Neoplasms/pathology , Animals , Cell Line, Tumor , Carcinoma, Squamous Cell/genetics , Carcinoma, Squamous Cell/pathology , Mice , Gene Expression Regulation, Neoplastic/drug effects , Serine-Arginine Splicing Factors/genetics , Serine-Arginine Splicing Factors/metabolism , DNA Methylation , Introns/genetics , Mice, Nude , Azacitidine/pharmacology , Oncogenes/geneticsABSTRACT
BACKGROUND: Neurological paraneoplastic syndromes are rarely the first manifestation of an underlying cancer. A high index of suspicion is thus needed to diagnose such conditions. Paraneoplastic limbic encephalitis is one such entity which is well described in association with small cell lung cancers, testicular germ cell tumors, breast cancers and ovarian tumors. This article describes the entity being associated with an ovarian tumor. CASE: A 36-year-old female presented with abnormal behaviour, mood swings and delusions. She was evaluated for her psychiatric symptoms and found to have an underlying ovarian tumor. Anti-NMDA receptor titers were strongly positive. She underwent oophorectomy, and post-operatively there was a significant improvement in her psychiatric symptoms. CONCLUSIONS: Ovarian tumors like teratomas are implicated in the pathogenesis of paraneoplastic limbic encephalitis. An underlying ovarian tumor must be evaluated in all young females presenting with sudden onset of psychiatric symptoms.
