Jonathan Andreas

A Systems Genetics Approach Identifies CXCL14, ITGAX, and LPCAT2 as Novel Aggressive Prostate Cancer Susceptibility Genes

Although prostate cancer typically runs an indolent course, a subset of men develop aggressive, fatal forms of this disease. We hypothesize that germline variation modulates susceptibility to aggressive prostate cancer. The goal of this work is to identify susceptibility genes using the C57BL/6-Tg(TRAMP)8247Ng/J (TRAMP) mouse model of neuroendocrine prostate cancer. Quantitative trait locus (QTL) mapping was performed in transgene-positive (TRAMPxNOD/ShiLtJ) F2 intercross males (nu200a=u200a228), which facilitated identification of 11 loci associated with aggressive disease development. Microarray data derived from 126 (TRAMPxNOD/ShiLtJ) F2 primary tumors were used to prioritize candidate genes within QTLs, with candidate genes deemed as being high priority when possessing both high levels of expression-trait correlation and a proximal expression QTL. This process enabled the identification of 35 aggressive prostate tumorigenesis candidate genes. The role of these genes in aggressive forms of human prostate cancer was investigated using two concurrent approaches. First, logistic regression analysis in two human prostate gene expression datasets revealed that expression levels of five genes (CXCL14, ITGAX, LPCAT2, RNASEH2A, and ZNF322) were positively correlated with aggressive prostate cancer and two genes (CCL19 and HIST1H1A) were protective for aggressive prostate cancer. Higher than average levels of expression of the five genes that were positively correlated with aggressive disease were consistently associated with patient outcome in both human prostate cancer tumor gene expression datasets. Second, three of these five genes (CXCL14, ITGAX, and LPCAT2) harbored polymorphisms associated with aggressive disease development in a human GWAS cohort consisting of 1,172 prostate cancer patients. This study is the first example of using a systems genetics approach to successfully identify novel susceptibility genes for aggressive prostate cancer. Such approaches will facilitate the identification of novel germline factors driving aggressive disease susceptibility and allow for new insights into these deadly forms of prostate cancer.

GNL3 and SKA3 are novel prostate cancer metastasis susceptibility genes.

Prostate cancer (PC) is very common in developed countries. However, the molecular determinants of PC metastasis are unclear. Previously, we reported that germline variation influences metastasis in the C57BL/6-Tg(TRAMP)8247Ng/J (TRAMP) mouse model of PC. These mice develop prostate tumors similar to a subset of poor outcome, treatment-associated human PC tumors. Here, we used TRAMP mice to nominate candidate genes and validate their role in aggressive human PC in PC datasets and cell lines. Candidate metastasis susceptibility genes were identified through quantitative trait locus (QTL) mapping in 201 (TRAMPxa0×xa0PWK/PhJ) F2 males. Two metastasis-associated QTLs were identified; one on chromosome 12 (LODxa0=xa05.86), and one on chromosome 14 (LODxa0=xa04.41). Correlation analysis using microarray data from (TRAMPxa0×xa0PWK/PhJ) F2 prostate tumors identified 35 metastasis-associated transcripts within the two loci. The role of these genes in susceptibility to aggressive human PC was determined through in silico analysis using multiple datasets. First, analysis of candidate gene expression in two human PC datasets demonstrated that five candidate genes were associated with an increased risk of aggressive disease and lower disease-free survival. Second, four of these genes (GNL3, MAT1A, SKA3, and ZMYM5) harbored SNPs associated with aggressive tumorigenesis in the PLCO/CGEMS GWAS of 1172 PC patients. Finally, over-expression of GNL3 and SKA3 in the PC-3 human PC cell line decreased in vitro cell migration and invasion. This novel approach demonstrates how mouse models can be used to identify metastasis susceptibility genes, and gives new insight into the molecular mechanisms of fatal PC.

Mapping Complex Traits in a Diversity Outbred F1 Mouse Population Identifies Germline Modifiers of Metastasis in Human Prostate Cancer

It is unclear how standing genetic variation affects the prognosis of prostate cancer patients. To provide one controlled answer to this problem, we crossed a dominant, penetrant mouse model of prostate cancer to Diversity Outbred mice, a collection of animals that carries over 40 million SNPs. Integration of disease phenotype and SNP variation data in 493 F1 males identified a metastasis modifier locus on Chromosome 8 (LODxa0= 8.42); further analysis identified thexa0genes Rwdd4, Cenpu, and Casp3 as functional effectors of this locus. Accordingly, analysis of over 5,300 prostate cancer patient samples revealed correlations between the presence of genetic variants atxa0these loci, their expression levels, cancer aggressiveness, and patient survival. We also observed that ectopic overexpression of RWDD4 and CENPU increased the aggressiveness of two human prostate cancer cell lines. In aggregate, our approach demonstrates how well-characterized genetic variation in mice can be harnessed in conjunction with systems genetics approaches to identify and characterize germline modifiers of human disease processes.

Analytical Validation of a Next-Generation Sequencing Assay to Monitor Immune Responses in Solid Tumors

We have developed a next-generation sequencing assay to quantify biomarkers of the host immune response in formalin-fixed, paraffin-embedded (FFPE) tumor specimens. This assay aims to provide clinicians with a comprehensive characterization of the immunologic tumor microenvironment as a guide for therapeutic decisions on patients with solid tumors. The assay relies on RNA-sequencing (seq) to semiquantitatively measure the levels of 43 transcripts related to anticancer immune responses and 11 transcripts that reflect the relative abundance of tumor-infiltrating lymphocytes, as well as on DNA-seq to estimate mutational burden. The assay has a clinically relevant 5-day turnaround time and can be conducted on as little as 2.5 ng of RNA and 1.8 ng of genomic DNA extracted from three to five standard FFPE sections. The standardized next-generation sequencing workflow produced sequencing reads adequate for clinical testing of matched RNA and DNA from several samples in a single run. Assay performance for gene-specific sensitivity, linearity, dynamic range, and detection threshold was estimated across a wide range of actual and artificial FFPE samples selected or generated to address preanalytical variability linked to specimen features (eg, tumor-infiltrating lymphocyte abundance, percentage of necrosis), and analytical variability linked to assay features (eg, batch size, run, day, operator). Analytical precision studies demonstrated that the assay is highly reproducible and accurate compared with established orthogonal approaches.

PD-L2 amplification and durable disease stabilization in patient with urothelial carcinoma receiving pembrolizumab

ABSTRACT We report the immunological profile of a patient with upper-tract urothelial carcinoma experiencing stable disease on pembrolizumab for 20 months. The tumor exhibited extensive infiltration by CD8+ cytotoxic T lymphocytes, low-to-moderate mutational burden, no PD-L1 staining by commercially available immunohistochemical assays, but amplification of CD274 (coding for PD-L1) and/or PDCD1LG2 (encoding PD-L2) by fluorescence in situ hybridization. RNA-seq revealed multiple biomarkers of an ongoing immune response and compensatory immune evasion, including moderate PD-L1 levels coupled with robust PD-L2 expression. Pending validation in additional patients, these findings suggest that PD-L2 expression levels may constitute a biomarker of response to immune checkpoint blockade in urothelial carcinoma.

Abstract 2261: DLGAP5, MAT1A, SKA3, and ZMYM5 are novel susceptibility genes for aggressive prostate cancer

Prostate cancer is a common disease with approximately 233,000 men estimated to be diagnosed in the United States alone in 2014. Yet, it is usually an indolent disease with only 13% of patients succumbing to prostate cancer, and the molecular determinants of aggressive prostate cancer remain unclear. Previously, we reported that germline variation influences disease aggressiveness in the C57BL/6-Tg(TRAMP)8247Ng/J (TRAMP) mouse model. These mice develop neuroendocrine prostate tumors similar to a subset of human prostate tumors associated with poor outcomes. Here, we used a multifaceted approach to identify candidate genes for susceptibility to aggressive prostate tumorigenesis and metastasis using the TRAMP mouse model. Candidate prostate cancer metastasis susceptibility genes were identified through quantitative trait locus (QTL) mapping in 201 (TRAMP x PWK/PhJ) F2 males. Two aggressive disease QTLs were identified; one for lymph node metastasis burden on chromosome 12 (LOD = 5.86) and one for distant metastasis-free survival on chromosome 14 (LOD = 4.41). Correlation analysis using microarray data derived from 27 (TRAMP x PWK/PhJ) F2 prostate tumors identified 35 metastasis-associated transcripts within the two loci. The role of these genes in susceptibility to aggressive human prostate cancer was analyzed in two different datasets. First, logistic regression and survival analyses in human prostate cancer gene expression datasets demonstrated that the expression levels of 5 of the 35 candidate genes was associated with both an increased risk of aggressive disease and a poorer disease-free survival. Second, four of these genes - DLGAP5, MAT1A, SKA3, and ZMYM5 - harbored SNPs associated with aggressive tumorigenesis in the PLCO/CGEMS GWAS cohort of 1,172 prostate cancer patients. This approach, novel to the prostate cancer field, demonstrates how mouse models can be used to identify aggressive disease susceptibility genes, and gives new insight into the molecular mechanisms of aggressive disease. Citation Format: Minnkyong Lee, Kendra A. Williams, Ying Hu, Jonathan Andreas, Shashankkumar J. Patel, Suiyuan Zhang, Nigel PS Crawford. DLGAP5, MAT1A, SKA3, and ZMYM5 are novel susceptibility genes for aggressive prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2261. doi:10.1158/1538-7445.AM2015-2261

Abstract 4952: Germline variation modulates susceptibility to aggressive disease development in a mouse model of prostate tumorigenesis

Although prostate cancer is common, with over 238,000 new cases being diagnosed in the US in 2012, it typically runs an indolent course with most men succumbing to unrelated disease processes. This is reflected in the low prostate cancer-specific mortality, with approximately 29,000 men succumbing in the same period. It is of critical importance to identify modifiers that increase susceptibility to aggressive disease to allow physicians to more accurately identify men at risk of fatal disease forms. The goal of this work is to map prostate tumor progression and metastasis modifier loci mapping using the C57BL/6-Tg(TRAMP)8247Ng/J (TRAMP) mouse model of aggressive neuroendocrine prostate carcinoma. We hypothesize that germline variation influences tumor progression and metastasis in prostate cancer. The effect of germline variation in TRAMP mice was investigated by crossing it to Collaborative Cross progenitor strains and quantifying tumor progression and metastasis in transgene-positive F1 males. Those strains with the greatest phenotypic variation from the wildtype TRAMP C57BL6/J mice were chosen for modifier mapping using an F2 intercross approach. F2 mice were genotyped using a linkage panel consisting of 1,449 SNPs and modifier loci analyzed using j/qtl. The greatest number of loci achieving genomewide significance were observed in the TRAMPxNOD/ShiLtJ F2 cross (n=232). Modifier loci associated with primary tumor growth were observed on chromosomes 4, 7 and 8. Additionally, loci associated with metastasis were observed on chromosomes 1, 11, 13 and 17. We have therefore identified multiple loci associated with aggressive disease development in a mouse model of prostate cancer. Candidate gene identification is ongoing, and focuses upon characterizing cis-eQTLs in TRAMPxNOD/ShiLtJ F2 primary tumors. Additionally, we are performing high resolution modifier mapping in TRAMPxJ:DO F1 mice. Our eventual aim is to confirm the relevance of candidate genes identified in the TRAMP mouse in human association cohorts. Citation Format: Kendra A. Williams, Sujata Bupp, Shashank Patel, Jonathan Andreas, Suiyuan Zhang, Alfredo Molinolo, Silvio Gutkind, Nigel Crawford. Germline variation modulates susceptibility to aggressive disease development in a mouse model of prostate tumorigenesis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4952. doi:10.1158/1538-7445.AM2014-4952