Effects of green tea epigallocatechin-3-gallate on transcription factors regulating expression of FLT3.

Purpose: In our previous paper we previously reported that epigallocatechin-3-gallate (EGCG) inhibits FLT3 expression in cell lines harboring FLT3 mutations. In this research, we carried on to investigate the influence of EGCG on FLT3 promoter activity and FLT3 transcription. Methods The effect of EGCG on the mRNA expression of flt3 and flt3-promoter activity was evaluated using semiquantitative reverse transcription-PCR and luciferase reporter assay. The gene expression profiling analysis was done for detecting the effect of EGCG on flt3-transcription factors. Then, the protein level of C-MyB was obsvered using western blot analysis.

Results: The results showed that EGCG reduced the transcription level of FLT3 by suppressing its promoter activity. By doing gene expression profile analysis in MOLM-13 cells established from acute monocytic leukemia patient with two mutations within FLT3 EXON 14 in a time-dependent manner, we found that the expression of mRNA of FLT3 was first observed to downregulate at 6 h together with the decreasing of Homeobox A9 (HOXA9) transcription factor after EGCG treatment. The changing of C/EBPα expression was found at 8 h. Interestingly, the reducing mRNA of c-Myb by EGCG was observed at 4 h, earlier than FLT3 was downregulated. There was no change in Meis Homeobox 1 (Meis1) by EGCG. We also found the protein level c-Myb was inhibited by EGCG in MOLM-13 and MOLM-14 cells after treating these cells with 60µM of EGCG for 8 h.

Conclusion: This data indicated the involvement of transcription factors in controlling the expression of FLT3 by EGCG.