Transcriptional regulation of the major zinc uptake protein hZip1 in prostate cancer cells

Abstract

AbstracthZip1 has been characterized as the major zinc uptake transporter regulating the accumulation of zinc in prostate cells. The mechanisms regulating expression of hZip1 have not been described. To explore the mechanisms of transcriptional regulation of the hZip1 gene, we determined the putative promoter sequence for hZip1 and identified the potential transcription start site within the predicted hZip1 promoter region. To further characterize the promoter region for basal hZip1 transcription, 3′ and 5′ deletion constructs and constructs with mutated binding sites for putative transcription factors were generated by PCR amplification and assessed for transcriptional activity with a luciferase reporter assay in PC-3 prostate cancer cells. The ability of the specific transcription factors to bind the hZip1 core promoter was confirmed by EMSA, Gel Supershift and ChIP assays. Our experiments identified the core promoter region responsible for constitutive expression of hZip1 and demonstrated critical roles for SP1 and CREB1 in transcriptional regulation of the hZip1 gene in prostate cancer cells.

Ras responsive element binding protein‐1 (RREB‐1) down‐regulates hZIP1 expression in prostate cancer cells

“…Our luciferase assays shown in Figure 2 locate the minimal promoter around TSS 1 (construct Prom(−1040/−721)) which confirms the results obtained by Makhov et al [6] On the other hand, the region around the TSS 2 did not lead to luciferase expression (construct PromΔ(−1507/−276)). The comparison of the luciferase activities with Prom(−1596/+121) and Prom(−1596/−622) reveals the presence of an inhibitory region located downstream of the TSS 1 between base pairs −622 and +121 (Fig.…”

“…1A). TSS1 is consistent with the TSS described by Makhov et al [6] The second TSS (TSS 2 ) is located 84 bp upstream of the translation start codon of hZIP1 and corresponds to a transcript with three exons (Fig. 1B).…”

“…Although our 5′RACE experiment identified two TSSs (−804 bp from a four exon transcript and −84 bp from a three exon transcript), luciferase assays located a minimal promoter only around the most 5′TSS. Therefore, our minimal promoter is consistent with the core promoter described by Makhov et al [6]. Interestingly, our luciferase assays allowed us to identify the 3′ region of hZIP1 promoter as a region involved in the inhibition of hZIP1 expression.…”

“…Makhov et al [6] recently characterized the transcription start site (TSS) and the minimal promoter of hZIP1 in prostate cancer cells. The location of the TSS is consistent with a transcript containing four exons.…”

Assessing prostate cancer growth with citrate measured by intact tissue proton magnetic resonance spectroscopy

“…As a very active research arena, the relationships between oncogenic mutations of prostate epithelial cells and the levels of zinc concentrations, zinc transporter protein expression, and the metabolic intensity of citrate in these cells have been proposed, 13,14 and widely tested, 15–17 including the proposals of imaging. 18,19 Briefly, it is known that zinc levels in the benign tissue of prostate peripheral zone are the highest among any soft tissue in the human body; these levels do not change in BPH, but are diminished in PCa.…”