Expression and regulation of an antisense RNA transcript of the human connective tissue growth factor gene in human tumour cells

Objective: To characterise a natural antisense transcript of connective tissue growth factor. Materials and Methods: RNA from several cell lines was analysed by RNase protection assay to detect antisense transcripts. To characterise the regulatory aspect of the transcribed area, chimeras were constructed in which the firefly luciferase gene was fused with the corresponding segment of ctgf/ccn2, and the gene expression was monitored. Results: A natural antisense transcript complementary to the 3′-untranslated region of ctgf/ccn2 mRNA in cultured human tumour cells was detected. The luciferase gene fused with the full-length antisense 3′-untranslated region showed strikingly low levels of luciferase expression compared with the control. Based on a series of deletion analyses, the major repressive element was located in the middle portion within the 3′-untranslated region, which corresponded to the antisense transcribed area. Conclusion: These results suggest that controlled expression of antisense RNAs against the 3′-untranslated region of ctgf/ccn2 mRNA may be involved in the determination of phenotypes in certain oral malignancies.