We evaluated 493 PCa cases from the Genomic Data Commons cohort using aCGH and RNAseq data through an in silico analysis and found that 124 from 449 genes related to immune and inflammatory responses were differentially expressed between PTEN loss (n=104) versus PTEN intact (n=398) cases. We have demonstrated that the 124 differentially expressed genes were associated with type I and II interferon responses and that the downstream regulators of these pathways are STATs proteins. We then evaluated the expression of PTEN, STAT1, pSTAT3, and CD8+ TIL through immunohistochemistry of 286 PCa cases from The Centre Hospitalier de l'Université de Montréal. In this cohort, we detected that PTEN protein loss is directly associated with reduced STAT1, pSTAT3, and CD8+ TIL density. In addition, we found that the downregulation of STAT1 and pSTAT3 increases the chance of PCa bone metastasis (Manuscript submitted to JAMA Oncology). In this proposal, we aim to validate the expression of the differentially expressed genes using a different cohort. We will perform immunohistochemistry in 150 PCa samples from Hospital das Clínicas - FMRP/USP in tissue microarrays. The immunohistochemistry will be conducted with the top ten most differentially expressed genes obtained in our in silico analysis. Next, we will quantify the mRNA expression of 770 immune markers of six PTEN loss and six PTEN intact PCa samples through NanoString nCounter PanCancer Immune Profiling platform. The results obtained with NanoString and IHC experiments will also be validated in another PCa cohort using RNAseq and whole genome sequencing data available through dbGaP data portal. Since it is likely that these expression data derive from a mixture of both tumor and stroma cells, we will then evaluate our overall NanoString immune cell profiling through an in silico analysis with CIBERSORT, a computational framework for accurately quantifying the relative abundance of various cell types present in a mixed population using RNA expression data. The experiments proposed will establish a primary relationship between the deletion status of the PTEN gene and its expression and the IFN-dependent activation of STAT1 and STAT3 protein in the tumor microenvironment of PCa. The identification of PTEN differential expression in cases of PCa with different disease risks can confirm the role of this gene in regulating immune and inflammatory responses that favor PCa tumor progression.
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