Transcriptional regulation of aldo-keto reductase 1C1 in HT29 @entity1 XXXX cells resistant to @entity1499 : role in the cell cycle and apoptosis.

@entity1 @entity15337 @entity1500 @entity3419 @entity28549 @entity1499 @entity694
While studying differentially expressed genes between sensitive and 10(-5)M @entity1499 ( @entity1500 ) resistant HT29 @entity1 @entity694 cells, we identified some members of the aldo-keto reductase (AKR) superfamily. The study was followed with the member @entity15337 (EC 1.1.1.213), validating its increase in mRNA and protein levels in @entity1500 resistant cells. The genomic content for @entity15337 remained unchanged between sensitive and resistant cells, thereby excluding a mechanism of @entity15337 gene amplification. Thus, we cloned the @entity15337 @entity1 promoter and performed luciferase experiments that revealed a transcriptional regulation of the gene in the resistant cells. Computational studies showed a putative binding site for the transcription factor @entity3419 . The co-transfection of @entity3419 or @entity28549 with different constructs of @entity15337 promoter deletions, including and excluding the proximal GC-box, demonstrated a key role for these factors in regulating @entity15337 transcriptional activity. Gel-shift assays revealed an increase in @entity3419 and @entity28549 binding in resistant compared to sensitive cells, without differences in @entity3419 protein levels. Dephosphorylation of the extracts coincided with a decrease in @entity3419 binding, which is consistent with a process of regulation of @entity3419 by phosphorylation. We also investigated the possible relationship between @entity15337 expression and @entity1500 action. Overexpression of @entity15337 counteracted the S-phase accumulation of cells and apoptosis caused by @entity1500 treatment. This suggests a role of @entity15337 in cell proliferation. Finally, overexpression of @entity15337 in @entity1500 sensitive HT29 cells conferred resistance to the chemotherapeutic agent and silencing of @entity15337 by means of iRNA technology sensitized the cells to @entity1500 .
