Shripad Sinari

Germline Mutations in HOXB13 and Prostate-Cancer Risk

BACKGROUND Family history is a significant risk factor for prostate cancer, although the molecular basis for this association is poorly understood. Linkage studies have implicated chromosome 17q21-22 as a possible location of a prostate-cancer susceptibility gene. METHODS We screened more than 200 genes in the 17q21-22 region by sequencing germline DNA from 94 unrelated patients with prostate cancer from families selected for linkage to the candidate region. We tested family members, additional case subjects, and control subjects to characterize the frequency of the identified mutations. RESULTS Probands from four families were discovered to have a rare but recurrent mutation (G84E) in HOXB13 (rs138213197), a homeobox transcription factor gene that is important in prostate development. All 18 men with prostate cancer and available DNA in these four families carried the mutation. The carrier rate of the G84E mutation was increased by a factor of approximately 20 in 5083 unrelated subjects of European descent who had prostate cancer, with the mutation found in 72 subjects (1.4%), as compared with 1 in 1401 control subjects (0.1%) (P=8.5x10(-7)). The mutation was significantly more common in men with early-onset, familial prostate cancer (3.1%) than in those with late-onset, nonfamilial prostate cancer (0.6%) (P=2.0x10(-6)). CONCLUSIONS The novel HOXB13 G84E variant is associated with a significantly increased risk of hereditary prostate cancer. Although the variant accounts for a small fraction of all prostate cancers, this finding has implications for prostate-cancer risk assessment and may provide new mechanistic insights into this common cancer. (Funded by the National Institutes of Health and others.).

Whole-genome sequencing of multiple myeloma from diagnosis to plasma cell leukemia reveals genomic initiating events, evolution, and clonal tides

The longitudinal evolution of a myeloma genome from diagnosis to plasma cell leukemia has not previously been reported. We used whole-genome sequencing (WGS) on 4 purified tumor samples and patient germline DNA drawn over a 5-year period in a t(4;14) multiple myeloma patient. Tumor samples were acquired at diagnosis, first relapse, second relapse, and end-stage secondary plasma cell leukemia (sPCL). In addition to the t(4;14), all tumor time points also shared 10 common single-nucleotide variants (SNVs) on WGS comprising shared initiating events. Interestingly, we observed genomic sequence variants that waxed and waned with time in progressive tumors, suggesting the presence of multiple independent, yet related, clones at diagnosis that rose and fell in dominance. Five newly acquired SNVs, including truncating mutations of RB1 and ZKSCAN3, were observed only in the final sPCL sample suggesting leukemic transformation events. This longitudinal WGS characterization of the natural history of a high-risk myeloma patient demonstrated tumor heterogeneity at diagnosis with shifting dominance of tumor clones over time and has also identified potential mutations contributing to myelomagenesis as well as transformation from myeloma to overt extramedullary disease such as sPCL.

Copy number and targeted mutational analysis reveals novel somatic events in metastatic prostate tumors

Advanced prostate cancer can progress to systemic metastatic tumors, which are generally androgen insensitive and ultimately lethal. Here, we report a comprehensive genomic survey for somatic events in systemic metastatic prostate tumors using both high-resolution copy number analysis and targeted mutational survey of 3508 exons from 577 cancer-related genes using next generation sequencing. Focal homozygous deletions were detected at 8p22, 10q23.31, 13q13.1, 13q14.11, and 13q14.12. Key genes mapping within these deleted regions include PTEN, BRCA2, C13ORF15, and SIAH3. Focal high-level amplifications were detected at 5p13.2-p12, 14q21.1, 7q22.1, and Xq12. Key amplified genes mapping within these regions include SKP2, FOXA1, and AR. Furthermore, targeted mutational analysis of normal-tumor pairs has identified somatic mutations in genes known to be associated with prostate cancer including AR and TP53, but has also revealed novel somatic point mutations in genes including MTOR, BRCA2, ARHGEF12, and CHD5. Finally, in one patient where multiple independent metastatic tumors were available, we show common and divergent somatic alterations that occur at both the copy number and point mutation level, supporting a model for a common clonal progenitor with metastatic tumor-specific divergence. Our study represents a deep genomic analysis of advanced metastatic prostate tumors and has revealed candidate somatic alterations, possibly contributing to lethal prostate cancer.

Genome and Transcriptome Sequencing in Prospective Metastatic Triple-Negative Breast Cancer Uncovers Therapeutic Vulnerabilities

Triple-negative breast cancer (TNBC) is characterized by the absence of expression of estrogen receptor, progesterone receptor, and HER-2. Thirty percent of patients recur after first-line treatment, and metastatic TNBC (mTNBC) has a poor prognosis with median survival of one year. Here, we present initial analyses of whole genome and transcriptome sequencing data from 14 prospective mTNBC. We have cataloged the collection of somatic genomic alterations in these advanced tumors, particularly those that may inform targeted therapies. Genes mutated in multiple tumors included TP53, LRP1B, HERC1, CDH5, RB1, and NF1. Notable genes involved in focal structural events were CTNNA1, PTEN, FBXW7, BRCA2, WT1, FGFR1, KRAS, HRAS, ARAF, BRAF, and PGCP. Homozygous deletion of CTNNA1 was detected in 2 of 6 African Americans. RNA sequencing revealed consistent overexpression of the FOXM1 gene when tumor gene expression was compared with nonmalignant breast samples. Using an outlier analysis of gene expression comparing one cancer with all the others, we detected expression patterns unique to each patients tumor. Integrative DNA/RNA analysis provided evidence for deregulation of mutated genes, including the monoallelic expression of TP53 mutations. Finally, molecular alterations in several cancers supported targeted therapeutic intervention on clinical trials with known inhibitors, particularly for alterations in the RAS/RAF/MEK/ERK and PI3K/AKT/mTOR pathways. In conclusion, whole genome and transcriptome profiling of mTNBC have provided insights into somatic events occurring in this difficult to treat cancer. These genomic data have guided patients to investigational treatment trials and provide hypotheses for future trials in this irremediable cancer. Mol Cancer Ther; 12(1); 104–16. ©2012 AACR.

Phylogeography of Francisella tularensis subspecies holarctica from the country of Georgia

BackgroundFrancisella tularensis, the causative agent of tularemia, displays subspecies-specific differences in virulence, geographic distribution, and genetic diversity. F. tularensis subsp. holarctica is widely distributed throughout the Northern Hemisphere. In Europe, F. tularensis subsp. holarctica isolates have largely been assigned to two phylogenetic groups that have specific geographic distributions. Most isolates from Western Europe are assigned to the B.Br.FTNF002-00 group, whereas most isolates from Eastern Europe are assigned to numerous lineages within the B.Br.013 group. The eastern geographic extent of the B.Br.013 group is currently unknown due to a lack of phylogenetic knowledge about populations at the European/Asian juncture and in Asia. In this study, we address this knowledge gap by describing the phylogenetic structure of F. tularensis subsp. holarctica isolates from the country of Georgia, and by placing these isolates into a global phylogeographic context.ResultsWe identified a new genetic lineage of F. tularensis subsp. holarctica from Georgia that belongs to the B.Br.013 group. This new lineage is genetically and geographically distinct from lineages previously described from the B.Br.013 group from Central-Eastern Europe. Importantly, this new lineage is basal within the B.Br.013 group, indicating the Georgian lineage diverged before the diversification of the other known B.Br.013 lineages. Although two isolates from the Georgian lineage were collected nearby in the Ukrainian region of Crimea, all other global isolates assigned to this lineage were collected in Georgia. This restricted geographic distribution, as well as the high levels of genetic diversity within the lineage, is consistent with a relatively older origin and localized differentiation.ConclusionsWe identified a new lineage of F. tularensis subsp. holarctica from Georgia that appears to have an older origin than any other diversified lineages previously described from the B.Br.013 group. This finding suggests that additional phylogenetic studies of F. tularensis subsp. holarctica populations in Eastern Europe and Asia have the potential to yield important new insights into the evolutionary history and phylogeography of this broadly dispersed F. tularensis subspecies.

Next-Generation Sequencing of Coccidioides immitis Isolated during Cluster Investigation

Next-generation sequencing enables use of whole-genome sequence typing (WGST) as a viable and discriminatory tool for genotyping and molecular epidemiologic analysis. We used WGST to confirm the linkage of a cluster of Coccidioides immitis isolates from 3 patients who received organ transplants from a single donor who later had positive test results for coccidioidomycosis. Isolates from the 3 patients were nearly genetically identical (a total of 3 single-nucleotide polymorphisms identified among them), thereby demonstrating direct descent of the 3 isolates from an original isolate. We used WGST to demonstrate the genotypic relatedness of C. immitis isolates that were also epidemiologically linked. Thus, WGST offers unique benefits to public health for investigation of clusters considered to be linked to a single source.

PTTG1 overexpression in adrenocortical cancer is associated with poor survival and represents a potential therapeutic target

BACKGROUND Adrenocortical carcinoma (ACC) is associated with poor survival rates. The objective of the study was to analyze ACC gene expression profiling data for prognostic biomarkers and therapeutic targets. METHODS We profiled 44 ACC and 4 normal adrenals on Affymetrix U133 Plus 2 expression microarrays. Pathway and transcriptional enrichment analysis was performed. Protein levels were determined by Western blot. Drug efficacy was assessed against ACC cell lines. Previously published expression datasets were analyzed for validation. RESULTS Pathway enrichment analysis identified marked dysregulation of cyclin-dependent kinases and mitosis. Overexpression of PTTG1, which encodes securin, a negative regulator of p53, was identified as a marker of poor survival. Median survival for patients with tumors expressing high PTTG1 levels (log2 ratio of PTTG1 to average β-actin <-3.04) was 1.8 years compared with 9.0 years if tumors expressed lower levels of PTTG1 (P < .0001). Analysis of a previously published dataset confirmed the association of high PTTG1 expression with a poor prognosis. Treatment of 2 ACC cell lines with vorinostat decreased securin levels and inhibited cell growth (median inhibition concentrations of 1.69 μmol/L and 0.891 μmol/L, for SW-13 and H295R, respectively). CONCLUSION Overexpression of PTTG1 is correlated with poor survival in ACC. PTTG1/securin is a prognostic biomarker and warrants investigation as a therapeutic target.

Paired Tumor and Normal Whole Genome Sequencing of Metastatic Olfactory Neuroblastoma

Background Olfactory neuroblastoma (ONB) is a rare cancer of the sinonasal tract with little molecular characterization. We performed whole genome sequencing (WGS) on paired normal and tumor DNA from a patient with metastatic-ONB to identify the somatic alterations that might be drivers of tumorigenesis and/or metastatic progression. Methodology/Principal Findings Genomic DNA was isolated from fresh frozen tissue from a metastatic lesion and whole blood, followed by WGS at >30X depth, alignment and mapping, and mutation analyses. Sanger sequencing was used to confirm selected mutations. Sixty-two somatic short nucleotide variants (SNVs) and five deletions were identified inside coding regions, each causing a non-synonymous DNA sequence change. We selected seven SNVs and validated them by Sanger sequencing. In the metastatic ONB samples collected several months prior to WGS, all seven mutations were present. However, in the original surgical resection specimen (prior to evidence of metastatic disease), mutations in KDR, MYC, SIN3B, and NLRC4 genes were not present, suggesting that these were acquired with disease progression and/or as a result of post-treatment effects. Conclusions/Significance This work provides insight into the evolution of ONB cancer cells and provides a window into the more complex factors, including tumor clonality and multiple driver mutations.

Whole genome sequencing reveals potential targets for therapy in patients with refractory KRAS mutated metastatic colorectal cancer

BackgroundThe outcome of patients with metastatic colorectal carcinoma (mCRC) following first line therapy is poor, with median survival of less than one year. The purpose of this study was to identify candidate therapeutically targetable somatic events in mCRC patient samples by whole genome sequencing (WGS), so as to obtain targeted treatment strategies for individual patients.MethodsFour patients were recruited, all of whom had received > 2 prior therapy regimens. Percutaneous needle biopsies of metastases were performed with whole blood collection for the extraction of constitutional DNA. One tumor was not included in this study as the quality of tumor tissue was not sufficient for further analysis. WGS was performed using Illumina paired end chemistry on HiSeq2000 sequencing systems, which yielded coverage of greater than 30X for all samples. NGS data were processed and analyzed to detect somatic genomic alterations including point mutations, indels, copy number alterations, translocations and rearrangements.ResultsAll 3 tumor samples had KRAS mutations, while 2 tumors contained mutations in the APC gene and the PIK3CA gene. Although we did not identify a TCF7L2-VTI1A translocation, we did detect a TCF7L2 mutation in one tumor. Among the other interesting mutated genes was INPPL1, an important gene involved in PI3 kinase signaling. Functional studies demonstrated that inhibition of INPPL1 reduced growth of CRC cells, suggesting that INPPL1 may promote growth in CRC.ConclusionsOur study further supports potential molecularly defined therapeutic contexts that might provide insights into treatment strategies for refractory mCRC. New insights into the role of INPPL1 in colon tumor cell growth have also been identified. Continued development of appropriate targeted agents towards specific events may be warranted to help improve outcomes in CRC.

Preclinical investigation of nanoparticle albumin-bound paclitaxel as a potential treatment for adrenocortical cancer.

Background:Traditional drug discovery methods have a limited role in rare cancers. We hypothesized that molecular technology including gene expression profiling could expose novel targets for therapy in adrenocortical carcinoma (ACC), a rare and lethal cancer. SPARC (secreted protein acidic rich in cysteine) is an albumin-binding matrix-associated protein that is proposed to act as a mechanism for the increased efficacy of a nanoparticle albumin-bound preparation of the antimicrotubular drug Paclitaxel (nab-paclitaxel). Methods:The transcriptomes of 19 ACC tumors and 4 normal adrenal glands were profiled on Affymetrix U133 Plus2 expression microarrays to identify genes representing potential therapeutic targets. Immunohistochemical analysis for target proteins was performed on 10 ACC, 6 benign adenomas, and 1 normal adrenal gland. Agents known to inhibit selected targets were tested in comparison with mitotane in the 2 ACC cell lines (H295R and SW-13) in vitro and in mouse xenografts. Results:SPARC expression is increased in ACC samples by 1.56 ± 0.44 (&mgr; ± SD) fold. Paclitaxel and nab-paclitaxel show in vitro inhibition of H295R and SW-13 cells at IC50 concentrations of 0.33 &mgr;M and 0.0078 &mgr;M for paclitaxel and 0.35 &mgr;M and 0.0087 &mgr;M for nab-paclitaxel compared with mitotane concentrations of 15.9 &mgr;M and 46.4 &mgr;M. In vivo nab-paclitaxel treatment shows a greater decrease in tumor weight in both xenograft models than mitotane. Conclusions:Biological insights garnered through expression profiling of ACC tumors suggest further investigation into the use of nab-paclitaxel for the treatment of ACC.