ABSTRACT: Hypoxia-independent gene expression signature associated with radiosensitisation of prostate cancer cell lines by histone deacetylase inhibition
Project description:We aimed to investigate gene expression associated with radiosensitisation of normoxic and hypoxic prostate cancer cells by the class I/II histone deacetylase inhibitor (HDACi) vorinostat. A pronounced deregulation of DNA repair and chromatin organization genes by vorinostat in DU 145 than in PC-3 or 22Rv1 was found and was a likly mechanism underlying radiosensitisation of DU 145. Expression of these genes was generally not affected by hypoxia and was altered by vorinostat in DU 145 towards the baseline levels of PC-3 and 22Rv1. A 56-gene expression signature associated with radiosensitisation under normoxia and hypoxia, including 8 genes with baseline expression characteristic of the radiosensitising effect was generated. These findings propose a hypoxia independent expression signature to predict the radiosensitising effect of vorinostat.
Project description:Histone deacetylase (HDAC) inhibitors are part of a new generation of epigenetic drugs for cancer treatment. It is known that histone acetylation plays a key role in controlling essential chromosome functions, including gene regulation, and this process has been linked with cancer development and progression. Better understanding of molecular mechanisms involving HDAC inhibitors is needed for the design of new targeted drugs, and also to evaluate the effectiveness of current treatments. In this study, an untargeted metabolomics approach was used to identify intracellular metabolite deregulation after treating cancer cell lines with the HDAC inhibitor HC-Toxin. Metabolomics analysis was performed using high resolution mass spectrometry, in combination with univariate and multivariate statistics and pathway analysis. HDAC inhibition showed highly specific metabolic changes in cancer cell lines compared to non-cancerous cells. In particular, N-acetyl-L-cysteine, N-acetylmethionine, and N-acetyl-L-carnitine showed a dose dependent change. Moreover, pathways controlling protein biosynthesis, as well as tryptophan, cysteine and methionine metabolism were significantly altered by HDAC inhibition. This study illustrates that HDAC inhibition has multiple effects on different metabolic pathways and our results can be extrapolated to inform on the molecular transitions in human cells.
Project description:We aimed to investigate the transcriptional program associated with pimonidazole staining in prostate cancer. A pimonidazole gene signature was identified that showed positive correlation to Ki67 labeling index, indicating increased proliferation in pimonidazole positive tumors. A positive correlation to clinical tumor stage and presence of lymph node metastasis was also found, consistent with associations between pimonidazole staining and clinico-pathological parameters. Moreover, the gene signature was associated with high Gleason score in a validation cohort of 59 patients and showed prognostic impact independent of Gleason score and other clinical markers in a watchful waiting validation cohort of 281 patients. Our work reveals the molecular basis of an aggressive prostate cancer phenotype reflected by pimonidazole staining, and suggests that genes involved in proliferation, DNA repair and hypoxia response contribute to this phenotype. We combined pimonidazole immunohistochemistry data and expression profiles to identify transcriptional program activated in pimonidazole positive tumors. Whole-genome gene expression profiles were determined in tumor biopsies from an investigation cohort of 46 patients, where 39 patients had received pimonidazole prior to surgery. Gene ontology analysis of 1046 genes upregulated in pimonidazole positive tumors, as defined by a staining fraction above 10%, showed significant enrichment of the biologic processes cell cycle, translation and cellular response to stress. Gene set analysis based on this result identified gene expressions in proliferation, DNA repair and hypoxia response as major parts of the transcriptional program associated with pimonidazole staining. Gene expression data of four prostate cancer cell lines were used to generate hypoxia response gene sets for this analysis. A signature of the 32 most essential genes in the program was constructed and shown to be associated with prostate cancer aggressiveness in two independent validation cohorts.
Project description:Systemic metabolic alterations associated with increased consumption of saturated fat and obesity are linked with increased risk of prostate cancer progression and mortality, but the molecular underpinnings of this association are poorly understood. Here, we demonstrate in a murine prostate cancer model, that high-fat diet (HFD) enhances the MYC transcriptional program through metabolic alterations that favour histone H4K20 hypomethylation at the promoter regions of MYC regulated genes, leading to increased cellular proliferation and tumour burden. Saturated fat intake (SFI) is also associated with an enhanced MYC transcriptional signature in prostate cancer patients. The SFI-induced MYC signature independently predicts prostate cancer progression and death. Finally, switching from a high-fat to a low-fat diet, attenuates the MYC transcriptional program in mice. Our findings suggest that in primary prostate cancer, dietary SFI contributes to tumour progression by mimicking MYC over expression, setting the stage for therapeutic approaches involving changes to the diet.
Project description:Hypoxia is a common feature of many solid tumors due to aberrant proliferation and angiogenesis that is associated with tumor progression and metastasis. Most of the well-known hypoxia effects are mediated through hypoxia-inducible factors (HIFs). Identification of the long-lasting effects of hypoxia beyond the immediate HIF-induced alterations could provide a better understanding of hypoxia-driven metastasis and potential strategies to circumvent it. Here, we uncovered a hypoxia-induced mechanism that exerts a prolonged effect to promote metastasis. In breast cancer patient-derived circulating tumor cell (CTC) lines and common breast cancer cell lines, hypoxia downregulated tumor intrinsic type I interferon (IFN) signaling and its downstream antigen presentation (AP) machinery in luminal breast cancer cells, via both HIF-dependent and HIF-independent mechanisms. Hypoxia induced durable IFN/AP suppression in certain cell types that was sustained after returning to normoxic conditions, presenting a “hypoxic memory” phenotype. Hypoxic memory of IFN/AP downregulation was established by specific hypoxic priming, and cells with hypoxic memory had an enhanced ability for tumorigenesis and metastasis. Overexpression of IRF3 enhanced IFN signaling and reduced tumor growth in normoxic, but not hypoxic, conditions. The histone deacetylase inhibitor (HDACi) entinostat upregulated IFN targets and erased the hypoxic memory. These results point to a mechanism by which hypoxia facilitates tumor progression through a long-lasting memory that provides advantages for CTCs during the metastatic cascade.
Project description:Hypoxia is a common feature of many solid tumors due to aberrant proliferation and angiogenesis that is associated with tumor progression and metastasis. Most of the well-known hypoxia effects are mediated through hypoxia-inducible factors (HIFs). Identification of the long-lasting effects of hypoxia beyond the immediate HIF-induced alterations could provide a better understanding of hypoxia-driven metastasis and potential strategies to circumvent it. Here, we uncovered a hypoxia-induced mechanism that exerts a prolonged effect to promote metastasis. In breast cancer patient-derived circulating tumor cell (CTC) lines and common breast cancer cell lines, hypoxia downregulated tumor intrinsic type I interferon (IFN) signaling and its downstream antigen presentation (AP) machinery in luminal breast cancer cells, via both HIF-dependent and HIF-independent mechanisms. Hypoxia induced durable IFN/AP suppression in certain cell types that was sustained after returning to normoxic conditions, presenting a “hypoxic memory” phenotype. Hypoxic memory of IFN/AP downregulation was established by specific hypoxic priming, and cells with hypoxic memory had an enhanced ability for tumorigenesis and metastasis. Overexpression of IRF3 enhanced IFN signaling and reduced tumor growth in normoxic, but not hypoxic, conditions. The histone deacetylase inhibitor (HDACi) entinostat upregulated IFN targets and erased the hypoxic memory. These results point to a mechanism by which hypoxia facilitates tumor progression through a long-lasting memory that provides advantages for CTCs during the metastatic cascade.
Project description:Background: Hypoxia gene signatures measured in a biopsy are promising biomarkers in prostate cancer. We determined the ability of a previously developed signature to correctly classify tumours as more or less hypoxic and investigated how intratumour heterogeneity affected its biomarker performance. Methods: The 32-gene signature was determined from gene expression data of 141 biopsies from the dominant (index) lesion of 94 patients treated with prostatectomy. Hypoxic fraction was measured by pimonidazole immunostaining of whole-mount and biopsy sections and used as reference standard for hypoxia. Results: The signature was correlated with hypoxic fraction in whole-mount sections, and the parameters showed almost the same association with tumour aggressiveness. Gene- and pimonidazole-based classification of patients differed considerably. However, the signature had low intratumour heterogeneity compared to hypoxic fraction in biopsies and showed prognostic significance in three independent cohorts. Conclusion: The biopsy-based 32-gene signature from the index lesion reflects hypoxia-related aggressiveness in prostate cancer.
Project description:miRNA expression profiling of prostate cancer cell lines, PC-3, DU145, LAPC-4, VCaP, LNCaP, 22rv1, and normal prostate epithelial cells, PrECs, was done after treating the cells with DNA demethylating agent 5-aza-2'-deoxycytidine (5azadC; Sigma-Aldrich, St. Louis, MO) and histone deacetylase inhibitor trichostatin A (TSA; Sigma-Aldrich). These treatments relieve epigenetic modifications, and thus reveal potentially epigenetically silenced miRNAs amongst the miRNAs with increased expression after the treatments.