Citations

Abstract Glioblastoma (GBM) is the most common malignant primary brain cancer. With a median survival of about a year, new approaches to treating this disease are necessary. To identify signaling molecules regulating GBM progression in a genetically engineered murine model of proneural GBM, we quantified phosphotyrosine-mediated signaling using mass spectrometry. Oncogenic signals, including phosphorylated ERK MAPK, PI3K, and PDGFR, were found to be increased in the murine tumors relative to brain. Phosphorylation of CDK1 pY15, associated with the G2 arrest checkpoint, was identified as the most differentially phosphorylated site, with a 14-fold increase in phosphorylation in the tumors. To assess the role of this checkpoint as a potential therapeutic target, syngeneic primary cell lines derived from these tumors were treated with MK-1775, an inhibitor of Wee1, the kinase responsible for CDK1 Y15 phosphorylation. MK-1775 treatment led to mitotic catastrophe, as defined by increased DNA damage and cell death by apoptosis. To assess the extensibility of targeting Wee1/CDK1 in GBM, patient-derived xenograft (PDX) cell lines were also treated with MK-1775. Although the response was more heterogeneous, on-target Wee1 inhibition led to decreased CDK1 Y15 phosphorylation and increased DNA damage and apoptosis in each line. These results were also validated in vivo, where single-agent MK-1775 demonstrated an antitumor effect on a flank PDX tumor model, increasing mouse survival by 1.74-fold. This study highlights the ability of unbiased quantitative phosphoproteomics to reveal therapeutic targets in tumor models, and the potential for Wee1 inhibition as a treatment approach in preclinical models of GBM. Mol Cancer Ther; 15(6); 1332–43. ©2016 AACR.

ABSTRACTEpithelial‐mesenchymal transition (EMT) is a process whereby epithelial cells assume mesenchymal characteristics to facilitate cancer metastasis. However, EMT also contributes to the initiation and development of primary tumors. Prior studies that explored the hypothesis that EMT gene variants contribute to epithelial ovarian carcinoma (EOC) risk have been based on small sample sizes and none have sought replication in an independent population. We screened 15,816 single‐nucleotide polymorphisms (SNPs) in 296 genes in a discovery phase using data from a genome‐wide association study of EOC among women of European ancestry (1,947 cases and 2,009 controls) and identified 793 variants in 278 EMT‐related genes that were nominally (P < 0.05) associated with invasive EOC. These SNPs were then genotyped in a larger study of 14,525 invasive‐cancer patients and 23,447 controls. A P‐value <0.05 and a false discovery rate (FDR) <0.2 were considered statistically significant. In the larger dataset, GPC6/GPC5 rs17702471 was associated with the endometrioid subtype among Caucasians (odds ratio (OR) = 1.16, 95% CI = 1.07–1.25, P = 0.0003, FDR = 0.19), whereas F8 rs7053448 (OR = 1.69, 95% CI = 1.27–2.24, P = 0.0003, FDR = 0.12), F8 rs7058826 (OR = 1.69, 95% CI = 1.27–2.24, P = 0.0003, FDR = 0.12), and CAPN13 rs1983383 (OR = 0.79, 95% CI = 0.69–0.90, P = 0.0005, FDR = 0.12) were associated with combined invasive EOC among Asians. In silico functional analyses revealed that GPC6/GPC5 rs17702471 coincided with DNA regulatory elements. These results suggest that EMT gene variants do not appear to play a significant role in the susceptibility to EOC.

Extracellular RNAs (exRNAs) have been identified in all tested biofluids and have been associated with a variety of extracellular vesicles, ribonucleoprotein complexes and lipoprotein complexes. Much of the interest in exRNAs lies in the fact that they may serve as signalling molecules between cells, their potential to serve as biomarkers for prediction and diagnosis of disease and the possibility that exRNAs or the extracellular particles that carry them might be used for therapeutic purposes. Among the most significant bottlenecks to progress in this field is the lack of robust and standardized methods for collection and processing of biofluids, separation of different types of exRNA‐containing particles and isolation and analysis of exRNAs. The Sample and Assay Standards Working Group of the Extracellular RNA Communication Consortium is a group of laboratories funded by the U.S. National Institutes of Health to develop such methods. In our first joint endeavour, we held a series of conference calls and in‐person meetings to survey the methods used among our members, placed them in the context of the current literature and used our findings to identify areas in which the identification of robust methodologies would promote rapid advancements in the exRNA field.

We investigated the pH dependence and the effects of thimerosal and dithiothreitol (DTT) upon the Ca2+ release induced by cADP-ribose (cADPR) and nicotinate–adenine dinucleotide phosphate (NAADP) in sea urchin egg homogenates. Both Ca2+ release triggered by cADPR and the binding of [3H]cADPR to sea urchin egg homogenates were decreased by alkalization of the assay media from pH 7.2 to 8.9. In contrast, NAADP-triggered Ca2+ release was not influenced by changes in pH. The Ca2+ release induced by cADPR was potentiated by thimerosal and inhibited by DTT, but neither thimerosal nor DTT had any effect upon the Ca2+ release induced by NAADP. We conclude that cADPR-sensitive Ca2+-release mechanisms are dependent on pH of the assay media and are sensitive to thiol group modification. On the other hand, these functional properties are not shared by NAADP-regulated Ca2+ channels.

Abstract Background: Genomic assessment of cancer has been revolutionized by Next-Generation sequencing and is increasingly being applied to guide clinical prognostic and therapeutic decision-making. Initial clinical applications have been limited to gene panels and whole exome based strategies due to challenges with time to reporting of results, specimen quantity, analyte quality, and ethical-legal-social issues (ELSI). Methods: Excisional or core tumor biopsies or bone marrow biopsies were obtained from consenting participants. Nucleic acid was extracted from fresh or frozen samples followed by WGS/WES/RNASeq on the Illumina HiSeq2000 or HiSeq2500 and bioinformatics analysis. Therapeutic targets were then prioritized by a multi-disciplinary Genomic Tumor Board (GTB) and CLIA validated using Sanger sequencing, RT-qPCR, FISH and/or IHC. Treatment was delivered using on/off-label FDA approved drugs, available clinical trials and single patient INDs. Results: We consented 64 and enrolled 35 patients with advanced, treatment-refractory cancers. Median age was 59 (range 27-91) with 62% male. The majority had ECOG scores of 1 (94%). A median of 79 (range 28-8891) potentially functional somatic point mutations were identified in each case. One to two mutations/case were further identified as therapeutically targetable in 60% of the cases. The median time from tissue acquisition to CLIA validated results was 116 days (range 42-282) with CLIA validation of targets achieved in 21 of 22 patients. Genomic, target directed treatment was ultimately instituted in 13 patients utilizing: on/off label FDA approved drugs (n = 9), clinical trial (n = 3) and single patient IND (n = 1). Preliminary clinical efficacy was noted in 5 patients (2 PR, 3 SD). Integration of WES, long-insert WGS and RNA-Seq identified a case with an ERRFI1 mutant allele present in only 11% of the DNA reads while 82% of the RNA-Seq reads had the mutant transcript. The patient was treated with erlotinib and achieved a partial response by RECIST criteria. In another case, a fusion between FGFR2-MGEA5 was observed in WES and RNA-Seq data leading to prioritization as a drug target. Reasons for patients not receiving targeted therapy included: inability to access treatment (n = 1), death prior to intended treatment (n = 3), results returned after death (n = 3), no targets identified (n = 2) and decision to pursue alternate therapy (n = 5). Conclusions: Integrating whole genome analysis in a CLIA setting is not only feasible, but also valuable, in the prioritization and selection of potential targeted therapies for patients with advanced tumors. Continued barriers to broad application include the need for shorter time to reporting as well as broad availability of therapies through basket studies. Citation Format: Mitesh J. Borad, Jan Egan, Mia Champion, Katherine Hunt, Robert McWilliams, Ann McCullough, Jessica Aldrich, Sara Nasser, Winnie Liang, Michael Barrett, David Craig, Ramesh Ramanathan, John Carpten, A. Keith Stewart, Alan Bryce. Implementation of CLIA enabled integrated whole genome (WGS)/exome (WES)/transcriptome (RNAseq) next-gen sequencing to identify therapeutically relevant targets in advanced cancer patients. [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 CT112. doi:10.1158/1538-7445.AM2015-CT112

Abstract Androgen deprivation therapy (ADT) for hormone-sensitive prostate cancer (HSPC) and chemotherapy for castration-resistant prostate cancer (CRPC) are considered standard of care. However, there are no clinical tests or factors that can reliably predict treatment responses for the advanced prostate cancer patients. Examination of tumor component in circulation, also known as liquid biopsy, has shown promise for predicting treatment outcomes and survival. To capture the tumor-derived genomic alterations and decrease the surrogacy of using PSA measurements as is currently performed, we propose a Plasma Genomic Abnormality (PGA) score and Treatment Efficacy (TEff) index based on copy number variations as estimated by cell free DNA (cfDNA) in plasma. We first performed whole genome and targeted sequencing (NimbleGen comprehensive cancer panel) to examine plasma cfDNA for tumor-associated genetic and genomic aberrations in 10 HSPC patients receiving ADT and 10 CRPC patients receiving chemotherapy. For each patient, we tested plasma from two time points: pre-treatment and 4 months post-treatment. We then calculated the PGA score by summing the most significant genomic abnormalities with higher PGA score indicating greater tumor DNA content in cfDNA. TEff index was derived from comparison of PGA score difference between treatments with higher TEff index reflecting a better treatment response. The sequencing-based copy number analysis revealed locus-specific gains or losses including those previously reported in prostate cancers, such as 8q gains, AR amplifications, PTEN losses and TMPRSS2-ERG fusions. We found that overall PGA score was significantly higher in CRPC patients than in HSPC patients (p&lt;0.0005), possibly reflecting increased tumor burden during the disease progression. Patients with low TEff index often demonstrated poor response to treatments, and patients with high initial PGA score or low TEff index tended to have poor overall survival. As examples of the PGA-based TEff associations with outcome we presented three CRPC patients including two with neuro-endocrine origin (small cell carcinoma). Comparison of mutational profiles between pre- and post-treatments showed that treatments caused more diverse gene mutations, in particular, in the genes involving androgen biosynthesis, AR activation, DNA repair and chemotherapy resistance, suggesting subclonal evolution of heterogeneous tumor genomes in response to these treatments. Our results strongly support the feasibility of using non-invasive liquid biopsy as a potential powerful tool to study biological mechanisms underlying therapy-specific resistance and monitor disease progression in the advanced prostate cancer. Further studies are needed to develop and validate the genomics-based PGA score and TEff index for clinical applications. Citation Format: Liang Wang, Shu Xia, Meijun Du, Rachel Ditmar, Tiezheng Yuan, Yongchen Guo, Yuan Wang, Adam Lee, Michael Tschannen, Elizabeth Worthey, Howard Jacobs, Chiang-Ching Huang, Manish Kohli. Plasma genetic and genomic abnormalities predict treatment response and clinical outcome in advanced 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 5231. doi:10.1158/1538-7445.AM2015-5231

Abstract Diffuse large B-cell lymphoma (DLBCL) is an aggressive subtype of non-Hodgkin lymphoma (NHL) and is the most common NHL subtype diagnosed worldwide. Some epidemiologic data have indicated differences in DLBCL incidence rates and subtype distributions between Eastern Asian and Western countries. The first large-scale genome-wide association study (GWAS) of DLBCL with over 4000 cases conducted among individuals of European ancestry recently identified five independent SNPs that achieved genome-wide significance, and two SNPs that showed a suggestive association with DLBCL risk. In order to evaluate whether Eastern Asians and individuals of European ancestry share similar genetic risk factors for this disease, we attempted to replicate these GWAS findings in a pooled series of 1124 DLBCL cases and 3596 controls from Hong Kong, South Korea, and Thailand. Three of the five genome-wide significant SNPs from the DLBCL GWAS were significantly associated with DLBCL in our study population, including the top finding from the GWAS, EXOC2 rs116446171, which achieved genome-wide significance in our data (per allele OR = 2.04, 95% CI = 1.63-2.56; ptrend = 3.9 × 10-10). Additionally, we observed a significant association with PVT1 rs13255292 (per allele OR = 1.34, 95% CI = 1.19-1.52; ptrend = 2.1 × 10-6), which was the second strongest finding in the GWAS, and with HLA-B rs2523607 (per allele OR = 3.05, 95% CI = 1.32-7.05; ptrend = 0.009). Our study, which provides the first evaluation in Eastern Asians of SNPs definitively associated with DLBCL risk in individuals of European ancestry, indicates that at least some of the genetic factors associated with risk of DLBCL are similar between these populations. Citation Format: Nathaniel Rothman, Bryan A. Bassig, James R. Cerhan, Wing-Yan Au, Hee Nam Kim, Suleeporn Sangrajrang, Wei Hu, Jovic Tse, Sonja Berndt, Tongzhang Zheng, Heping Zhang, Pattarapong Pornsopone, Je-Jung Lee, Hyeoung-Joon Kim, Christine F. Skibola, Joseph Vijai, Laurie Burdette, Meredith Yeager, Paul Brennan, Min-Ho Shin, Raymond Liang, Stephen Chanock, Qing Lan. Genetic susceptibility to diffuse large B-cell lymphoma in a pooled study of three Eastern Asian populations. [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 4626. doi:10.1158/1538-7445.AM2015-4626

Abstract Background: Genome-wide association studies (GWAS) have so far reported 12 loci associated with serous epithelial ovarian cancer (EOC) risk. We hypothesized that some of these loci function through nearby transcription factor (TF) genes and that putative target genes of these TFs as identified by coexpression may also be enriched for additional EOC risk associations. Methods: We selected TF genes within 1 Mb of the top signal at the 12 genome-wide significant risk loci. Mutual information, a form of correlation, was used to build networks of genes strongly coexpressed with each selected TF gene in the unified microarray dataset of 489 serous EOC tumors from The Cancer Genome Atlas. Genes represented in this dataset were subsequently ranked using a gene-level test based on results for germline SNPs from a serous EOC GWAS meta-analysis (2,196 cases/4,396 controls). Results: Gene set enrichment analysis identified six networks centered on TF genes (HOXB2, HOXB5, HOXB6, HOXB7 at 17q21.32 and HOXD1, HOXD3 at 2q31) that were significantly enriched for genes from the risk-associated end of the ranked list (P &lt; 0.05 and FDR &lt; 0.05). These results were replicated (P &lt; 0.05) using an independent association study (7,035 cases/21,693 controls). Genes underlying enrichment in the six networks were pooled into a combined network. Conclusion: We identified a HOX-centric network associated with serous EOC risk containing several genes with known or emerging roles in serous EOC development. Impact: Network analysis integrating large, context-specific datasets has the potential to offer mechanistic insights into cancer susceptibility and prioritize genes for experimental characterization. Cancer Epidemiol Biomarkers Prev; 24(10); 1574–84. ©2015 AACR.