Hypoxia-independent downregulation of hypoxia inducible factor 1 targets by androgen deprivation therapy in prostate cancer.

ABSTRACT: Hypoxia inducible factor 1 (HIF1) has been shown to cooperate with the androgen receptor (AR) in activation of oncogenic pathways in prostate cancer (PCa). Here we hypothesized that HIF1 also plays a role in PCa response to androgen deprivation therapy (ADT). Comparison of gene expression profiles of androgen exposed (AE) and androgen deprived (AD) CWR22 PCa xenografts identified 596 upregulated and 748 downregulated genes after ADT. Gene ontology (GO) analysis of the differentially expressed genes showed significant enrichment of the biological processes cell proliferation, cell cycle and metabolism and suggested suppression of these processes after ADT. A set of 80 hypoxia-inducible genes were identified in 22Rv1 and LNCaP cell lines treated with hypoxia and showed considerable overlap (53%) with the downregulated genes. Immunostaining of the hypoxia marker pimonidazole showed no difference between AE- and AD-tumors. Comparison of the differentially expressed genes with lists of 1115 direct AR- and 276 direct HIF1-target genes identified 138 AR- and 40 HIF1-targets that were regulated after ADT, including six shared AR- and HIF1-targets for which downregulation was confirmed with RT-PCR. Most HIF1-targets were downregulated and included in the significant biological processes and the set of hypoxia-inducible genes. The downregulation of HIF1-targets was consistent with decreased HIF1A immunostaining in AD- compared to AE-tumors (p=0.002). A decrease in HIF1A immunostaining after ADT was also demonstrated in a cohort of 35 PCa patients (p<0.001). These data suggest suppressed HIF1-signaling after ADT and a shared role of HIF1 and AR in the regressive phase of PCa after ADT. Prostate cancer xenografts were subjected to adrogen deprivation therapy and analysed with regard to changes in gene expressions. Cell culture experiments were performed to generate prostate cancer specific gene lists associated with hypoxia.

ORGANISM(S): Homo sapiens

SUBMITTER: Heidi Lyng 

PROVIDER: E-GEOD-42868 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress