Ahmet Kurdoglu

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.

Niche adaptation and genome expansion in the chlorophyll d-producing cyanobacterium Acaryochloris marina

Acaryochloris marina is a unique cyanobacterium that is able to produce chlorophyll d as its primary photosynthetic pigment and thus efficiently use far-red light for photosynthesis. Acaryochloris species have been isolated from marine environments in association with other oxygenic phototrophs, which may have driven the niche-filling introduction of chlorophyll d. To investigate these unique adaptations, we have sequenced the complete genome of A. marina. The DNA content of A. marina is composed of 8.3 million base pairs, which is among the largest bacterial genomes sequenced thus far. This large array of genomic data is distributed into nine single-copy plasmids that code for >25% of the putative ORFs. Heavy duplication of genes related to DNA repair and recombination (primarily recA) and transposable elements could account for genetic mobility and genome expansion. We discuss points of interest for the biosynthesis of the unusual pigments chlorophyll d and α-carotene and genes responsible for previously studied phycobilin aggregates. Our analysis also reveals that A. marina carries a unique complement of genes for these phycobiliproteins in relation to those coding for antenna proteins related to those in Prochlorococcus species. The global replacement of major photosynthetic pigments appears to have incurred only minimal specializations in reaction center proteins to accommodate these alternate pigments. These features clearly show that the genus Acaryochloris is a fitting candidate for understanding genome expansion, gene acquisition, ecological adaptation, and photosystem modification in the cyanobacteria.

Integrated genomic characterization reveals novel, therapeutically relevant drug targets in FGFR and EGFR pathways in sporadic intrahepatic cholangiocarcinoma.

Advanced cholangiocarcinoma continues to harbor a difficult prognosis and therapeutic options have been limited. During the course of a clinical trial of whole genomic sequencing seeking druggable targets, we examined six patients with advanced cholangiocarcinoma. Integrated genome-wide and whole transcriptome sequence analyses were performed on tumors from six patients with advanced, sporadic intrahepatic cholangiocarcinoma (SIC) to identify potential therapeutically actionable events. Among the somatic events captured in our analysis, we uncovered two novel therapeutically relevant genomic contexts that when acted upon, resulted in preliminary evidence of anti-tumor activity. Genome-wide structural analysis of sequence data revealed recurrent translocation events involving the FGFR2 locus in three of six assessed patients. These observations and supporting evidence triggered the use of FGFR inhibitors in these patients. In one example, preliminary anti-tumor activity of pazopanib (in vitro FGFR2 IC50≈350 nM) was noted in a patient with an FGFR2-TACC3 fusion. After progression on pazopanib, the same patient also had stable disease on ponatinib, a pan-FGFR inhibitor (in vitro, FGFR2 IC50≈8 nM). In an independent non-FGFR2 translocation patient, exome and transcriptome analysis revealed an allele specific somatic nonsense mutation (E384X) in ERRFI1, a direct negative regulator of EGFR activation. Rapid and robust disease regression was noted in this ERRFI1 inactivated tumor when treated with erlotinib, an EGFR kinase inhibitor. FGFR2 fusions and ERRFI mutations may represent novel targets in sporadic intrahepatic cholangiocarcinoma and trials should be characterized in larger cohorts of patients with these aberrations.

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.

The genome of Heliobacterium modesticaldum, a phototrophic representative of the Firmicutes containing the simplest photosynthetic apparatus.

Despite the fact that heliobacteria are the only phototrophic representatives of the bacterial phylum Firmicutes, genomic analyses of these organisms have yet to be reported. Here we describe the complete sequence and analysis of the genome of Heliobacterium modesticaldum, a thermophilic species belonging to this unique group of phototrophs. The genome is a single 3.1-Mb circular chromosome containing 3,138 open reading frames. As suspected from physiological studies of heliobacteria that have failed to show photoautotrophic growth, genes encoding enzymes for known autotrophic pathways in other phototrophic organisms, including ribulose bisphosphate carboxylase (Calvin cycle), citrate lyase (reverse citric acid cycle), and malyl coenzyme A lyase (3-hydroxypropionate pathway), are not present in the H. modesticaldum genome. Thus, heliobacteria appear to be the only known anaerobic anoxygenic phototrophs that are not capable of autotrophy. Although for some cellular activities, such as nitrogen fixation, there is a full complement of genes in H. modesticaldum, other processes, including carbon metabolism and endosporulation, are more genetically streamlined than they are in most other low-G+C gram-positive bacteria. Moreover, several genes encoding photosynthetic functions in phototrophic purple bacteria are not present in the heliobacteria. In contrast to the nutritional flexibility of many anoxygenic phototrophs, the complete genome sequence of H. modesticaldum reveals an organism with a notable degree of metabolic specialization and genomic reduction.

Alzheimer's disease is associated with altered expression of genes involved in immune response and mitochondrial processes in astrocytes

Alzheimers disease (AD) is characterized by deficits in cerebral metabolic rates of glucose in the posterior cingulate (PC) and precuneus in AD subjects, and in APOEε4 carriers, decades before the onset of measureable cognitive deficits. However, the cellular and molecular basis of this phenotype remains to be clarified. Given the roles of astrocytes in energy storage and brain immunity, we sought to characterize the transcriptome of AD PC astrocytes. Cells were laser capture microdissected from AD (n = 10) and healthy elderly control (n = 10) subjects for RNA sequencing. We generated >5.22 billion reads and compared sequencing data between controls and AD patients. We identified differentially expressed mitochondria-related genes including TRMT61B, FASTKD2, and NDUFA4L2, and using pathway and weighted gene coexpression analyses, we identified differentially expressed immune response genes. A number of these genes, including CLU, C3, and CD74, have been implicated in beta amyloid generation or clearance. These data provide key insights into astrocyte-specific contributions to AD, and we present this data set as a publicly available resource.

Extramedullary myeloma whole genome sequencing reveals novel mutations in Cereblon, proteasome subunit G2 and the glucocorticoid receptor in multi drug resistant disease.

Extramedullary disease (EMD) in Multiple Myeloma (MM) is characterized by the detection of monoclonal plasma cells outside the bone marrow niche, and is frequently associated with poor prognosis. Here we describe novel genomic events leading to drug refractory disease in a heavily pretreated 37-year-old IgG-kappa MM patient presenting with progressive, multi-drug refractory EMD. For the first time we report an acquired truncating mutation of Cereblon (CRBN) as well as point mutations in proteasome subunit G2 and the glucocorticoid receptor as an explanation for drug resistance. Initial myeloma treatment for the patient occurred over multiple years and included the immunomodulatory drugs (IMiDs) thalidomide and lenalidomide, the proteasome inhibitor bortezomib, cortiosteroids, radiation, one autologous and two allogeneic transplantations. She experienced extramedullary relapse, presenting as an extensive neck mass and smaller soft tissue nodules in the upper left triceps. The most recent therapy immediately prior to genomic sequencing was hyper-CVAD (hyperfractionated cyclophosphamide, vincristine, doxorubicin and dexamethasone) incorporating alkylating agent cyclophosphamide with transient minor response. The patient was then enrolled in a pilot study utilizing next generation sequencing (NGS) to identify novel markers and potential therapeutic targets. Samples were acquired with patient consent in compliance with Mayo Clinic Institutional Review Board. For this study we completed array comparative genomic hybridization, whole exome, whole genome (insert = 1 kb) and RNA sequencing (RNASeq) of a biopsy taken from the neck mass to thoroughly interrogate the tumour genome of this patient. The presence of mutations of interest was evaluated by capillary sequencing in an expanded cohort of 25 CD138+ MM samples with low CRBN expression. The neck mass pathology confirmed sheets of atypical plasma cells, kappa light chain restriction, CD138+, CD20− and CD45−. Array comparative genomic hybridization revealed multiple copy number abnormalities, most notably del1(p13.2–34.2), monosomy 13 and monosomy X. Therapy subsequent to biopsy for genome sequencing was with pomalidomide and dexamethasone without response. Unfortunately, the patient succumbed to her disease in less than the 12 weeks required at the time for sequencing and data analysis. Sequencing revealed a highly disturbed genome (Figure 1) consisting of 4 somatic insertions/deletions, 38 intra-chromosomal rearrangements, and 35 translocations, including the high risk marker and initiating tumour event t(14;16). Furthermore, 271 nonsynonymous, somatic point mutations were detected in genes including KRAS, PIK3CA, ATM, and NFKB2 (Table I). Importantly, a Q99* truncating mutation as well as a R283K point mutation were observed in CRBN, that we recently demonstrated as essential for the anti-MM action of IMiDs (Zhu, et al 2011). To our knowledge this is the first documented mutation of Cereblon in a primary myeloma sample. Additional sequencing of CRBN in the expanded cohort of 25 patients revealed a synonymous mutation in only one sample. Figure 1 Circos plot depicting genome wide somatic variants, rearrangements and copy number changes derived from next generation sequencing. Numbers with circles around them indicate the following: 1) somatic single nucleotide variation (SNV), 2) location of SNV ... Table I Summary of clinically relevant single nucleotide variations We also observed in the patient biopsy a potentially clinically relevant nonsynonymous point mutation in proteasome assembly chaperone 2, PSMG2 (E171K). PSMG2 is a proteasome assembly protein involved in mammalian 20S proteasome maturation (Hirano, et al 2005). Mutations in proteasome assembly components contribute to proteasome inhibitor resistance (Keats, et al 2007), possibly explaining this patient’s bortezomib-refractory disease. Capillary sequencing of PSMG2 in our expanded cohort revealed no mutations, although exonic deletion of PSMG2 has also been reported in myeloma (Walker, et al 2012). The last nonsynonymous point mutation associated with drug resistance was identified in NR3C1 (G369A), a glucocorticoid receptor. Mutation of NR3C1 has been associated with resistance to steroid therapy (Bray and Cotton 2003), which this patient received and proved refractory. No NR3C1 mutations were identified in our expanded cohort and none have been previously reported in other myeloma genomes (Chapman, et al 2011, Walker, et al 2012). Mutations in NR3C1 have however been described in the glucocorticoid resistant MM.1R cell line (Moalli, et al 1992). Patients with low NR3C1 expression levels who received thalidomide demonstrated better progression-free survival and overall survival than those with low NR3C1 who did not receive thalidomide (Heuck, et al 2012). While these mutations suggest causality of drug-refractory disease, they do not identify pathways that can be exploited with targeted therapies. Additional mutations were observed in pathways for which targeted therapies are available. This patient had mutations in KRAS (G12C) and in ATM (T1985I), both of which affect the signalling of MEK downstream, thus making MEK a therapeutic target of interest in this patient. While there are no approved MEK inhibitors available for MM treatment, more than 100 trials are currently investigating MEK inhibitors, of which three of these trials are being conducted in MM patients (www.clinicaltrials.gov). The patient tumour also contained canonical, activating mutations in PIK3CA (E542K). Interestingly, one study demonstrated that 64% of PIK3CA mutations occur in exon 9, where codon 542 is located. Moreover, 19% of patients with PIK3CA mutations also presented with KRAS mutations, of which 9% are G12C (Janku, et al 2012), found in our patient. The PI3K pathway is vitally important as it regulates downstream targets, such as AKT and MTOR, which are responsible for cell proliferation, growth, survival and metastasis (Bartholomeusz and Gonzalez-Angulo 2012). In addition, a number of clinical trials are currently investigating PIK3 inhibitors (www.clinicaltrials.gov). In summary, this is the first description of CRBN mutations in a primary myeloma sample and furthermore of a “triple negative” MM patient possessing mutations probably contributing to resistance to all three major drug classes utilized in MM therapy. These mutations were not replicated in our validation cohort of 25 patients with low level CRBN expression and functional data have not yet been obtained, thus further investigation is necessary to better understand the mutation frequency and the functional significance of mutation in these genes. In summary, our approach utilizing comprehensive next generation sequencing not only identified mutations suggestive of the patient’s refractory disease, but also revealed unforeseen therapeutic options highlighting the importance of this technology in advancing individualized medicine.

Metabolic flexibility revealed in the genome of the cyst-forming α-1 proteobacterium Rhodospirillum centenum

BackgroundRhodospirillum centenum is a photosynthetic non-sulfur purple bacterium that favors growth in an anoxygenic, photosynthetic N2-fixing environment. It is emerging as a genetically amenable model organism for molecular genetic analysis of cyst formation, photosynthesis, phototaxis, and cellular development. Here, we present an analysis of the genome of this bacterium.ResultsR. centenum contains a singular circular chromosome of 4,355,548 base pairs in size harboring 4,105 genes. It has an intact Calvin cycle with two forms of Rubisco, as well as a gene encoding phosphoenolpyruvate carboxylase (PEPC) for mixotrophic CO2 fixation. This dual carbon-fixation system may be required for regulating internal carbon flux to facilitate bacterial nitrogen assimilation. Enzymatic reactions associated with arsenate and mercuric detoxification are rare or unique compared to other purple bacteria. Among numerous newly identified signal transduction proteins, of particular interest is a putative bacteriophytochrome that is phylogenetically distinct from a previously characterized R. centenum phytochrome, Ppr. Genes encoding proteins involved in chemotaxis as well as a sophisticated dual flagellar system have also been mapped.ConclusionsRemarkable metabolic versatility and a superior capability for photoautotrophic carbon assimilation is evident in R. centenum.

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.

Novel pathogenic variants and genes for myopathies identified by whole exome sequencing

Neuromuscular diseases (NMD) account for a significant proportion of infant and childhood mortality and devastating chronic disease. Determining the specific diagnosis of NMD is challenging due to thousands of unique or rare genetic variants that result in overlapping phenotypes. We present four unique childhood myopathy cases characterized by relatively mild muscle weakness, slowly progressing course, mildly elevated creatine phosphokinase (CPK), and contractures. We also present two additional cases characterized by severe prenatal/neonatal myopathy. Prior extensive genetic testing and histology of these cases did not reveal the genetic etiology of disease. Here, we applied whole exome sequencing (WES) and bioinformatics to identify likely causal pathogenic variants in each pedigree. In two cases, we identified novel pathogenic variants in COL6A3. In a third case, we identified novel likely pathogenic variants in COL6A6 and COL6A3. We identified a novel splice variant in EMD in a fourth case. Finally, we classify two cases as calcium channelopathies with identification of novel pathogenic variants in RYR1 and CACNA1S. These are the first cases of myopathies reported to be caused by variants in COL6A6 and CACNA1S. Our results demonstrate the utility and genetic diagnostic value of WES in the broad class of NMD phenotypes.