[Transcriptional activity of WT1 gene promoter and enhancer in diverse cell lines]

The objective of study was to investigate tissue-specific transcriptional activity of WT1 (Wilms' tumor gene) promoter and enhancer in cell lines with diverse tissue origin for leukemic gene therapy depending on WT1 transcriptional regulation elements. WT1 promoter and enhancer were ligated into pEGFP-1 to construct a recombinant vectors with EGFP gene as a reporter. By using electroporation or lipofectamine, the resultant constructs were transfected into 13 cell lines including WT1-expressing hematopoietic cell lines (K562, NB4, THP-1 and SHI-1), WT1-nonexpressing hematopoietic cell lines (U937 and Jurkat), WT1-expressing nonhematopoietic cell lines (MCF-7, T47D and 293) and WT1-nonexpressing nonhematopoietic cell lines (ECV304, SMMC7721, HT-29 and SHG44). The mean fluorescence intensity (MFI) of EGFP representing the transcriptional activities of promoter and/or enhancer was analyzed by using flow cytometry in the transfected cells which stably expressed EGFP. The results indicated that the vectors, pEWP containing WT1 promoter and pEWPA containing both WT1 enhancer and promoter, were constructed by recombinant DNA technique. Among nonhematopoietic cell lines, pEWP induced the highest EGFP expression in ECV304 (16.54 +/- 2.45 times as high as pEGFP-1), mildly higher in MCF-7 and SHG44 (9.46 +/- 1.10 and 7.29 +/- 0.73 times of pEGFP-1 level), and lowest in HT-29 (0.99 +/- 0.02 times as much as pEGFP-1) respectively. Among hematopoietic cell lines, EGFP expression was highest in K562 cell line (2.93 +/- 0.27 times of pEGFP-1), which was statistically higher than those in Jurkat and SHI-1 cell lines (0.74 +/- 0.03 and 0.84 +/- 0.09 times of pEGFP-1 level) respectively. pEWPA, with WT1 enhancer inserted at Afl II site near SV40 polyA, increased basal transcription levels of the WT1 promoter in HT-29, SHI-1 and K562 cells by 4.81, 3.06 and 1.01-fold respectively. It is concluded that the transcriptional activities of WT1 promoter in the recombinant vector seem unrelated to the constitutional expression level of endogenous WT1 gene. The WT1 enhancer promotes the transcriptional activities of WT1 promoter in some of the cell lines regardless of the hematopoietic tissue origin.