Sir Peter MacCallum Department of Oncology - Research Publications
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ItemExploring the oncoproteomic response of human prostate cancer to therapeutic radiation using data-independent acquisition (DIA) mass spectrometry(WILEY, 2018-06-01)INTRODUCTION: The development of radioresistance in prostate cancer (PCa) is an important clinical issue and is still largely uninformed by personalized molecular characteristics. The aim of this study was to establish a platform that describes the early oncoproteomic response of human prostate tissue to radiation therapy (RT) using a prospective human tissue cohort. METHODS: Fresh and fixed transperineal biopsies from eight men with clinically localized tumors were taken prior to and 14 days following a single fraction of high-dose-rate brachytherapy. Quantitative protein analysis was achieved using an optimized protein extraction pipeline and subsequent data-independent acquisition mass spectroscopy (DIA-MS). Ontology analyses were used to identify enriched functional pathways, with the candidates further interrogated in formalin-fixed paraffin-embedded tissue biopsies from five additional patients. RESULTS: We obtained a mean coverage of 5660 proteins from fresh tissue biopsies; with the principal post-radiation change observed being an increase in levels amongst a total of 49 proteins exhibiting abundance changes. Many of these changes in abundance varied between patients and, typically to prostate cancer tissue, exhibited a high level of heterogeneity. Ontological analysis revealed the enrichment of the protein activation cascades of three immunological pathways: humoral immune response, leukocyte mediated immunity and complement activation. These were predominantly associated with the extracellular space. We validated significant expression differences in between 20% and 61% of these candidates using the separate fixed-tissue cohort and established their feasibility as an experimental tissue resource by acquiring quantitative data for a mean of 5152 proteins per patient. DISCUSSION: In this prospective study, we have established a sensitive and reliable oncoproteomic pipeline for the analysis of both fresh and formalin-fixed human PCa tissue. We identified multiple pathways known to be radiation-responsive and have established a powerful database of candidates and pathways with no current association with RT. This information may be beneficial in the advancement of personalized therapies and potentially, predictive biomarkers.
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ItemE6AP promotes prostate cancer by reducing p27 expression(IMPACT JOURNALS LLC, 2017-06-27)Prostate cancer (PC) is the most common cancer in men. Elevated levels of E3 ligase, E6-Associated Protein (E6AP) were previously linked to PC, consistent with increased protein expression in a subset of PC patients. In cancers, irregular E3 ligase activity drives proteasomal degradation of tumor suppressor proteins. Accordingly, E3 ligase inhibitors define a rational therapy to restore tumor suppression. The relevant tumor suppressors targeted by E6AP in PC are yet to be fully identified. In this study we show that p27, a key cell cycle regulator, is a target of E6AP in PC. Down regulation of E6AP increases p27 expression and enhances its nuclear accumulation in PC. We demonstrate that E6AP regulates p27 expression by inhibiting its transcription in an E2F1-dependent manner. Concomitant knockdown of E6AP and p27 partially restores PC cell growth, supporting the contribution of p27 to the overall effect of E6AP on prostate tumorigenesis. Overall, we unravelled the E6AP-p27 axis as a new promoter of PC, exposing an attractive target for therapy through the restoration of tumor suppression.
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ItemE6AP Promotes a Metastatic Phenotype in Prostate Cancer(CELL PRESS, 2019-12-20)Although primary prostate cancer is largely curable, progression to metastatic disease is associated with very poor prognosis. E6AP is an E3 ubiquitin ligase and a transcriptional co-factor involved in normal prostate development. E6AP drives prostate cancer when overexpressed. Our study exposed a role for E6AP in the promotion of metastatic phenotype in prostate cells. We revealed that elevated levels of E6AP in primary prostate cancer correlate with regional metastasis and demonstrated that E6AP promotes acquisition of mesenchymal features, migration potential, and ability for anchorage-independent growth. We identified the metastasis suppressor NDRG1 as a target of E6AP and showed it is key in E6AP induction of mesenchymal phenotype. We showed that treatment of prostate cancer cells with pharmacological agents upregulated NDRG1 expression suppressed E6AP-induced cell migration. We propose that the E6AP-NDRG1 axis is an attractive therapeutic target for the treatment of E6AP-driven metastatic prostate cancer.
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ItemP53: A Guardian of Immunity Becomes Its Saboteur through Mutation(MDPI, 2020-05)Awareness of the importance of immunity in controlling cancer development triggered research into the impact of its key oncogenic drivers on the immune response, as well as their value as targets for immunotherapy. At the heart of tumour suppression is p53, which was discovered in the context of viral infection and now emerges as a significant player in normal and cancer immunity. Wild-type p53 (wt p53) plays fundamental roles in cancer immunity and inflammation. Mutations in p53 not only cripple wt p53 immune functions but also sinisterly subvert the immune function through its neomorphic gain-of-functions (GOFs). The prevalence of mutant p53 across different types of human cancers, which are associated with inflammatory and immune dysfunction, further implicates mutant p53 in modulating cancer immunity, thereby promoting tumorigenesis, metastasis and invasion. In this review, we discuss several mutant p53 immune GOFs in the context of the established roles of wt p53 in regulating and responding to tumour-associated inflammation, and regulating innate and adaptive immunity. We discuss the capacity of mutant p53 to alter the tumour milieu to support immune dysfunction, modulate toll-like receptor (TLR) signalling pathways to disrupt innate immunity and subvert cell-mediated immunity in favour of immune privilege and survival. Furthermore, we expose the potential and challenges associated with mutant p53 as a cancer immunotherapy target and underscore existing therapies that may benefit from inquiry into cancer p53 status.
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ItemHigh dose-rate brachytherapy of localized prostate cancer converts tumors from cold to hot(BMJ PUBLISHING GROUP, 2020)BACKGROUND: Prostate cancer (PCa) has a profoundly immunosuppressive microenvironment and is commonly immune excluded with few infiltrative lymphocytes and low levels of immune activation. High-dose radiation has been demonstrated to stimulate the immune system in various human solid tumors. We hypothesized that localized radiation therapy, in the form of high dose-rate brachytherapy (HDRBT), would overcome immune suppression in PCa. METHODS: To investigate whether HDRBT altered prostate immune context, we analyzed preradiation versus postradiation human tissue from a cohort of 24 patients with localized PCa that received HDRBT as primary treatment (RadBank cohort). We performed Nanostring immune gene expression profiling, digital spatial profiling, and high-throughput immune cell multiplex immunohistochemistry analysis. We also resolved tumor and nontumor zones in spatial and bioinformatic analyses to explore the immunological response. RESULTS: Nanostring immune profiling revealed numerous immune checkpoint molecules (eg, B7-H3, CTLA4, PDL1, and PDL2) and TGFβ levels were increased in response to HDRBT. We used a published 16-gene tumor inflammation signature (TIS) to divide tumors into distinct immune activation states (high:hot, intermediate and low:cold) and showed that most localized PCa are cold tumors pre-HDRBT. Crucially, HDRBT converted 80% of these 'cold'-phenotype tumors into an 'intermediate' or 'hot' class. We used digital spatial profiling to show these HDRBT-induced changes in prostate TIS scores were derived from the nontumor regions. Furthermore, these changes in TIS were also associated with pervasive changes in immune cell density and spatial relationships-in particular, between T cell subsets and antigen presenting cells. We identified an increased density of CD4+ FOXP3+ T cells, CD68+ macrophages and CD68+ CD11c+ dendritic cells in response to HDRBT. The only subset change specific to tumor zones was PDL1- macrophages. While these immune responses were heterogeneous, HDRBT induced significant changes in immune cell associations, including a gained T cell and HMWCK+ PDL1+ interaction in tumor zones. CONCLUSION: In conclusion, we showed HDRBT converted "cold" prostate tumors into more immunologically activated "hot" tissues, with accompanying spatially organized immune infiltrates and signaling changes. Understanding and potentially harnessing these changes will have widespread implications for the future treatment of localized PCa, including rational use of combination radio-immunotherapy.