The effects of 5-aza-2'-deoxycytidine and trichostatin A on FBI-1 gene expression in choriocarcinoma cell lines

Abstract

Choriocarcinoma is a rare, aggressive malignant epithelial tumor that can be arisen from gestational or non-gestational origins. Gestational choriocarcinoma is found primarily in uterus and is a malignant form of gestational trophoblastic disease. The tumor can easily metastasize to other organs through blood vessels and fatal outcome would be resulted if untreated. Nevertheless, the underlying pathogenesis is not fully explored and understood.

FBI-1 is a proto-oncogene and acts as a transcriptional repressor for many cellular processes. Overexpression of FBI-1 was observed in various types of cancers including gestational choriocarcinoma. However, little is known on the mechanisms of regulation of FBI-1 gene expression. In this study, by treating with two epigenetic remodeling drugs, 5-aza-2’-deoxycytidine (5-aza-dc) and trichostatin A (TSA), mRNA and protein expressions of FBI-1 were investigated in gestational choriocarcinoma cell lines, JEG-3 and JAR by using quantitative real-time PCR and western blotting. The morphological changes and cell survival after treatment of 5-aza-dc or TSA on JEG-3 and JAR cell lines was also assessed, the latterby3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT) assay.

This study demonstrated that FBI-1 protein was overexpressed in JEG-3 and JAR cells compared to normal trophoblastic cell line. Moreover, FBI-1 expressions in JEG-3 and JAR cells were down-regulated in TSA treatment but remained unchanged in 5-aza-dc treatment. It implies that HDAC inhibitor is able to regulate the expression of FBI-1 gene.

After treatment with TSA at 0.3Mor 0.6M, both JEG-3 and JAR cells demonstrated significant morphological changes when comparing with the untreated controls, becoming elongated, distorted, rounder and smalleras well as increasingly detached and floating suggestive of cell death. Such changes were not significantly observed in 5-aza-dctreated cells. In addition, more significant reduction in cell survival as assessed by MTT assay was found in TSA than in 5-aza-dc treatment. This may be related to the decrease inFBI-1 expression after TSA treatment.

In summary, histone modification may play a role in the regulation of FBI-1 expression in gestational choriocarcinoma cells affecting the cell survival.