The miR-143 target TARDBP may serve as a marker for cervical cancer

Abstract

BACKGROUND: The microRNA miR-143 has been demonstrated to be downregulated in cervical cancer. However its targets in cervical cancer are not well characterized but could potentially yield useful markers for the malignancy. OBJECTIVES: (1) To determine the cellular expression pattern of miR-143 in normal and cancerous cervices. (2) To explore miR-143 and its targets as makers of cervical cancer. DESIGN: Cells expressing miR-143 in normal cervix, CIN, and SCC were identified with in situ hybridization. Ten potential miR-143 target genes were chosen from in silico prediction using three algorithms (PicTar, miRanda and miRtarget2). Their transcript and protein expression levels were characterized in five cervical cancer cell lines (HeLa, SiHa, CaSki, C4-I and C33A) and in HeLa with miR-143 overexpression. One of the genes was verified as true target by luciferase reporter assay. Its expression in cervical tissues was assessed with immunohistochemistry. RESULTS: miR-143 was strongly expressed in blood vessels and smooth muscle in all samples. Weaker and scattered staining could be detected in normal epithelium. However miR-143 could not be found in SCC cells. Ten potential miR-143 target genes were chosen from in silico prediction (ITGA6, MSI2, PHF6, TARDBP, VAPB, MAP3K7, CRELD1, AKAP6, CBFB, RBM24). All candidates except MAP3K7 displayed certain degree of upregulation in at least one of the cervical cancer cell lines in comparison with HaCat. However, only TARDBP and PHF6 were downregulated by miR-143 overexpression in HeLa. Luciferase transcript with the 3’UTR of TARDBP was also found to be downregulated by miR-143. Such down-regulation was abolished when the miR-143 binding site was mutated. TARDBP was found to be overexpressed in SCC in comparison with CIN2/3, CIN1 and normal cervix by immunocytochemistry. CONCLUSION: TARDBP is a target of miR-143 and is overexpressed in SCC. TARDBP may serve as an immune-histochemical marker for detection of cervical cancer.