A review on the interactions between the tumour microenvironment and androgen receptor signaling in prostate cancer

Prostate cancer growth is controlled by androgen receptor signaling via both androgen-dependent and androgen-independent pathways. Furthermore, the prostate is an immune competent organ with inflammatory changes both within the systemic and local environment contributing to the reprogramming of the prostatic epithelium with consistently elevated lymphocyte infiltration and pro-inflammatory cytokines being found in prostate cancer. The crosstalk between the tumour microenvironment and androgen receptor signaling is complex with both pro-tumorigenic and anti-tumourigenic roles observed. However, despite an increase in immune checkpoint inhibitors and inflammatory signaling blockades available for a range of cancer types, we are yet to see substantial progress in the treatment of prostate cancer. Therefore, this review aims to summarize the tumour microenvironment and its impact on androgen receptor signaling in prostate cancer

Androgen receptor phosphorylation at serine 81 and serine 213 in castrate-resistant prostate cancer

Background: Despite increases in diagnostics and effective treatments, over 300,000 men die from prostate cancer highlighting the need for specific and differentiating biomarkers. AR phosphorylation associates with castrate-resistance, with pARser213 promoting transcriptional activity. We hypothesise that combined pARser81 and pARser213 reduces survival and would benefit from dual-targeting androgen-dependent and Akt-driven disease. Methods: Immunohistochemistry and immunofluorescence were performed on matched hormone-naive and castrate-resistant prostate cancer samples. TempO-Seq gene profiling was analysed using DESeq2 package. LNCaP-AI cells were stimulated with DHT or EGF. WST-1 assays were performed to determine effects of Enzalutamide and BKM120 on cell viability. Results: Following the development of castrate-resistance, pARser81 expression reduced and pARser213 expression increased. Castrate-resistance pARser81 expression was not associated with survival but high pARser213 expression was associated with reduced survival from relapse. Combined high pARser81 and pARser213 was associated with reduced survival from relapse. pARser81 expression was induced by 10 nM DHT or 10 nM EGF and pARser213 expression was induced by treatment with 10 nM EGF in LNCaP-AI cells. Cell viability was reduced following treatment with 10 nM Enzalutamide and 10 nM BKM120. Eight genes were differentially expressed between hormone-naive and castrate-resistant tumours and twenty-five genes were differentially expressed between castrate-resistant tumours with high and low pARser213 expression. Conclusion: Combined pARser81 and pARser213 provides a novel prognostic biomarker for castrate-resistant disease and a potential predictive and therapeutic target for prostate cancer. Further studies will be required to investigate the combined effects of targeting AR and PI3K/AKT signalling

The Intestinal Microbiota in Colorectal Cancer Metastasis - Passive Observer or Key Player?

The association between colorectal cancer (CRC) and alterations in intestinal microbiota has been demonstrated by several studies, and there is increasing evidence that bacteria are an important component of the tumour microenvironment. Bacteria may contribute to the development of CRC metastasis by signalling through metabolites, promoting epithelial-mesenchymal transition, creating an immunosuppressive microenvironment and through the impairment of the gut-vascular barrier. Host immunity and intestinal microbiome symbiosis play a key role in determining innate and adaptive immune responses at the local and systemic level. How this gut-systemic axis might contribute to the development of CRC metastasis is however unclear. Several clinical trials are investigating the impact of microbiome-targeted interventions on the systemic inflammatory response, treatment-related complications, and side effects. This review examines pre-clinical and clinical studies which have examined the role of microbes in relation to CRC metastasis, the mechanisms which may contribute to tumour dissemination, and directions for future work