Crosstalk between transcription factors in regulation of the human glutathione S-transferase P1 gene expression in Me45 melanoma cells

Abstract

Aim. The human GSTP1 is a major enzyme of phase II detoxification in the most cell types. Aberrant expression of GSTP1 is associated with carcinogenesis and development of multidrug resistance. The GSTP1 gene expression is regulated at multiple levels including transcriptional, post-transcriptional and post-translational. We concentrated our attention on the transcriptional level of regulation. Methods. Transient transfection of Me45 melanoma cells with constructs containing the luciferase gene under the control of complete and truncated GSTP1 promoter was utilized to identify a role of different promoter regions in regulation of the gene transcription in Me45 cells. To identify the transcription factors, interacting with the GSTP1 promoter sites, the competitive EMSA and super shift assay were applied. Results. GSTP1 transcription in Me45 cells is positively regulated by binding NF-kB to the cognate site and ERb in complex with unknown protein to the ARE site; the complex of ERb with c-Fos negatively regulates the gene expression via CRE site. The interaction of c-Fos/ERb with GSTP1 CRE site and indirect interaction of ERb with GSTP1 ARE were identified. Conclusions. The positive regulation of the human GSTP1 gene in Me45 melanoma cells is exerted via NF-kB and ARE sites and the negative one via CRE site of the promoter. ERb is indirectly involved in the regulation of GSTP1 transcription. It is bound via c-Fos with CRE site and via unknown protein with ARE site.