Function and Regulation of Phosphatidylinositol 3,4,5-Triphosphate-Dependent Rac Exchanger 1 (P-Rex1) in Cancer
type: CreativeWork
description: Up-regulated phosphatidylinositol-3,4,5-trisphosphate-dependent Rac exchange factor 1 (P-Rex1) promotes tumorigenesis and metastasis of various cancers, and thus could be a potential therapeutic target. The first objective of my study was to determine the molecular mechanism regulating P-Rex1 gene expression. We found that P-Rex1 expression was much higher in metastatic prostate cancer cells than in prostate epithelial cells and non-metastatic prostate cancer cells. Histone deacetylase (HDAC) inhibitors or silence of endogenous HDAC1 and HDAC2 markedly elevated P-Rex1 transcription in non-metastatic prostate cancer cells, whereas overexpression of recombinant HDAC1 in metastatic prostate cancer cells suppressed P-Rex1 expression. HDAC inhibitor trichostatin A (TSA) also significantly increased P-Rex1 promoter activity and caused acetylated histones to accumulate and associate with the P-Rex1 promoter. One Sp1 site, essential for basal promoter activity, was identified as critical for the TSA effect. TSA treatment did not alter the DNA-binding activity of Sp1 toward the P-Rex1 promoter; however, it facilitated the dissociation of the repressive HDAC1 and HDAC2 from the Sp1 binding region. Interestingly, HDAC1 association with Sp1 and with the P-Rex1 promoter was much weaker in metastatic prostate cancer PC-3 cells than in non-metastatic prostate cancer cells, and HDAC inhibitors only had very modest stimulatory effects on P-Rex1 promoter activity and P-Rex1 expression in PC-3 cells. Altogether, our studies demonstrate that HDACs could regulate P-Rex1 gene transcription by interaction with Sp1 and by region-specific changes in histone acetylation within the P-Rex1 promoter. Disassociation of HDACs from Sp1 on the P-Rex1 promoter may contribute to aberrant up-regulation of P-Rex1 in cancer. |HDAC inhibitors are promising anti-cancer drugs because they can restore expression of silenced tumor suppressor genes. However, our data caution that these inhibitors could have s…
abstract: Up-regulated phosphatidylinositol-3,4,5-trisphosphate-dependent Rac exchange factor 1 (P-Rex1) promotes tumorigenesis and metastasis of various cancers, and thus could be a potential therapeutic target. The first objective of my study was to determine the molecular mechanism regulating P-Rex1 gene expression. We found that P-Rex1 expression was much higher in metastatic prostate cancer cells than in prostate epithelial cells and non-metastatic prostate cancer cells. Histone deacetylase (HDAC) inhibitors or silence of endogenous HDAC1 and HDAC2 markedly elevated P-Rex1 transcription in non-metastatic prostate cancer cells, whereas overexpression of recombinant HDAC1 in metastatic prostate cancer cells suppressed P-Rex1 expression. HDAC inhibitor trichostatin A (TSA) also significantly increased P-Rex1 promoter activity and caused acetylated histones to accumulate and associate with the P-Rex1 promoter. One Sp1 site, essential for basal promoter activity, was identified as critical for the TSA effect. TSA treatment did not alter the DNA-binding activity of Sp1 toward the P-Rex1 promoter; however, it facilitated the dissociation of the repressive HDAC1 and HDAC2 from the Sp1 binding region. Interestingly, HDAC1 association with Sp1 and with the P-Rex1 promoter was much weaker in metastatic prostate cancer PC-3 cells than in non-metastatic prostate cancer cells, and HDAC inhibitors only had very modest stimulatory effects on P-Rex1 promoter activity and P-Rex1 expression in PC-3 cells. Altogether, our studies demonstrate that HDACs could regulate P-Rex1 gene transcription by interaction with Sp1 and by region-specific changes in histone acetylation within the P-Rex1 promoter. Disassociation of HDACs from Sp1 on the P-Rex1 promoter may contribute to aberrant up-regulation of P-Rex1 in cancer. |HDAC inhibitors are promising anti-cancer drugs because they can restore expression of silenced tumor suppressor genes. However, our data caution that these inhibitors could have s…
author: Wong, Chuu-Yun
language: en_US
date published: 2013-09-16
date modified: 2026-07-24T01:50:46Z
provider: Creighton University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Creighton University

PropertyValue
property ID: Handle
value: http://hdl.handle.net/10504/46068