Abstract

Background: All-trans retinoic acid (ATRA) is a natural vitamin A derivative that has a profound effect on the regulation of cell growth, differentiation and death.

Aim: To investigate the tissue dynamic and cellular invasion effects of ATRA in choriocarcinoma (CCA), an aggressive trophoblastic tumour, by using a three-dimensional organotypic culture model system and cell invasion assay, respectively.

Methods: An organotypic culture model of two CCA cell lines, JAR and JEG, was established. The effects of 1 μM ATRA on proliferation, differentiation and apoptosis on this CCA model were assessed by morphological assessment of the mitotic and apoptotic figures as well as by Ki-67 and caspase-related M30 cytoDeath antibody immunohistochemistry and the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL) assay. The effect of ATRA on p53 and its regulated protein product, WAF1/Cip1, was also evaluated with DO7 and p21^WAF1 antibodies, respectively. Moreover, the effect of ATRA on cellular (CCA) invasion was also investigated with Cell Invasion Kit on the JEG cell line.

Results: ATRA was found to induce marked apoptosis in organotypic cultures of both cell lines, as evidenced by increased M30-positive cells (p<0.0001) and increased TUNEL-positive cells (p<0.0001) in treated cultures; to decrease proliferation, as evidenced by decreased Ki-67-positive cells (p<0.0001); and to decrease p53-DO7 immunoreactivity (p<0.0001) and increase p21^WAF1 (p<0.0001) immunoreactivity. 1.5 μM ATRA was found to effectively inhibit JEG cell invasion in the cell invasion assay.

Conclusion: ATRA treatment was found to inhibit invasion and proliferation and enhance apoptosis, probably by the activation of caspases and induction of differentiation. ATRA and synthetic retinoids may be alternative agents for the treatment of CCA.