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"Carpten, John"
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Exploring the genetic and molecular basis of differences in multiple myeloma of individuals of African and European descent
2024
Multiple Myeloma is a typical example of a neoplasm that shows significant differences in incidence, age of onset, type, and frequency of genetic alterations between patients of African and European ancestry. This perspective explores the hypothesis that both genetic polymorphisms and spontaneous somatic mutations in the
TP53
tumor suppressor gene are determinants of these differences. In the US, the rates of occurrence of MM are at least twice as high in African Americans (AA) as in Caucasian Americans (CA). Strikingly, somatic
TP53
mutations occur in large excess (at least 4–6-fold) in CA versus AA. On the other hand,
TP53
contains polymorphisms specifying amino-acid differences that are under natural selection by the latitude of a population and have evolved during the migrations of humans over several hundred thousand years. The p53 protein plays important roles in DNA strand break repair and, therefore, in the surveillance of aberrant DNA recombination, leading to the B-cell translocations that are causal in the pathogenesis of MM. We posit that polymorphisms in one region of the
TP53
gene (introns 2 and 3, and the proline-rich domain) specify a concentration of the p53 protein with a higher capacity to repress translocations in CA than AA patients. This, in turn, results in a higher risk of acquiring inactivating, somatic mutations in a different region of the
TP53
gene (DNA binding domain) in CA than in AA patients. Such a mechanism, by which the polymorphic status of a gene influencing its own “spontaneous” mutation frequency, may provide a genetic basis to address ethnicity-related differences in the incidence and phenotypes of many different forms of cancer.
Journal Article
Translating RNA sequencing into clinical diagnostics: opportunities and challenges
by
Carpten, John D.
,
Byron, Sara A.
,
Van Keuren-Jensen, Kendall R.
in
631/1647/2217/2218
,
631/1647/514/2254
,
631/208/191/2018
2016
Key Points
RNA-based measurements have the potential for application across diverse areas of human health, including disease diagnosis, prognosis and therapeutic selection. Current clinical applications include infectious diseases, cancer, transplant medicine and fetal monitoring.
RNA sequencing (RNA-seq) allows for the detection of a wide variety of RNA species, including mRNA, non-coding RNA, pathogen RNA, chimeric gene fusions, transcript isoforms and splice variants, and provides the capability to quantify known, pre-defined RNA species and rare RNA transcript variants within a sample. In addition to differential expression and detection of novel transcripts, RNA-seq also supports the detection of mutations and germline variation for hundreds to thousands of expressed genetic variants, facilitating assessment of allele-specific expression of these variants.
Circulating RNAs and small regulatory RNAs, such as microRNAs, are very stable. These RNA species are vigorously being tested for their potential as biomarkers. However, there are currently few agreed upon methods for isolation or quantitative measurements and a current lack of quality controls that can be used to test platform accuracy and sample preparation quality.
Analytical, bioinformatic and regulatory challenges exist, and ongoing efforts toward the establishment of benchmark standards, assay optimization for clinical conditions and demonstration of assay reproducibility are required to expand the clinical utility of RNA-seq.
RNA sequencing (RNA-seq) is a powerful approach for comprehensive analyses of transcriptomes. This Review describes the widespread potential applications of RNA-seq in clinical medicine, such as detecting disease-associated mutations and gene expression disruptions, as well as characteristic non-coding RNAs, circulating extracellular RNAs or pathogen RNAs. The authors also highlight the challenges in adopting RNA-seq routinely into clinical practice.
With the emergence of RNA sequencing (RNA-seq) technologies, RNA-based biomolecules hold expanded promise for their diagnostic, prognostic and therapeutic applicability in various diseases, including cancers and infectious diseases. Detection of gene fusions and differential expression of known disease-causing transcripts by RNA-seq represent some of the most immediate opportunities. However, it is the diversity of RNA species detected through RNA-seq that holds new promise for the multi-faceted clinical applicability of RNA-based measures, including the potential of extracellular RNAs as non-invasive diagnostic indicators of disease. Ongoing efforts towards the establishment of benchmark standards, assay optimization for clinical conditions and demonstration of assay reproducibility are required to expand the clinical utility of RNA-seq.
Journal Article
Comprehensive molecular profiling of 718 Multiple Myelomas reveals significant differences in mutation frequencies between African and European descent cases
by
Auclair, Daniel
,
Kittles, Rick A.
,
Jewell, Scott
in
Adult
,
Biology and Life Sciences
,
Black or African American
2017
Multiple Myeloma (MM) is a plasma cell malignancy with significantly greater incidence and mortality rates among African Americans (AA) compared to Caucasians (CA). The overall goal of this study is to elucidate differences in molecular alterations in MM as a function of self-reported race and genetic ancestry. Our study utilized somatic whole exome, RNA-sequencing, and correlated clinical data from 718 MM patients from the Multiple Myeloma Research Foundation CoMMpass study Interim Analysis 9. Somatic mutational analyses based upon self-reported race corrected for ancestry revealed significant differences in mutation frequency between groups. Of interest, BCL7A, BRWD3, and AUTS2 demonstrate significantly higher mutation frequencies among AA cases. These genes are all involved in translocations in B-cell malignancies. Moreover, we detected a significant difference in mutation frequency of TP53 and IRF4 with frequencies higher among CA cases. Our study provides rationale for interrogating diverse tumor cohorts to best understand tumor genomics across populations.
Journal Article
Validation of Myc-Associated Protein X (MAX) regulation in growth hormone secreting and nonfunctional pituitary adenoma
by
Zada, Gabriel
,
Shiroishi, Mark S.
,
Tucker, Douglass W.
in
Adenoma
,
Adenoma - pathology
,
Binding sites
2023
Many patients with growth hormone-secreting pituitary adenoma (GHPA) fail to achieve biochemical remission, warranting investigation into epigenetic and molecular signatures associated with tumorigenesis and hormonal secretion. Prior work exploring the DNA methylome showed Myc-Associated Protein X (MAX), a transcription factor involved in cell cycle regulation, was differentially methylated between GHPA and nonfunctional pituitary adenoma (NFPA). We aimed to validate the differential DNA methylation and related MAX protein expression profiles between NFPA and GHPA.
DNA methylation levels were measured in 52 surgically resected tumors (37 NFPA, 15 GHPA) at ~100,000 known MAX binding sites derived using ChIP-seq analysis from ENCODE. Findings were correlated with MAX protein expression using a constructed tissue microarray (TMA). Gene ontology analysis was performed to explore downstream genetic and signaling pathways regulated by MAX.
GHPA had more hypomethylation events across all known MAX binding sites. Of binding sites defined using ChIP-seq analysis, 1,551 sites had significantly different methylation patterns between the two cohorts; 432 occurred near promoter regions potentially regulated by MAX, including promoters of TNF and MMP9. Gene ontology analysis suggested enrichment in genes involved in oxygen response, immune system regulation, and cell proliferation. Thirteen MAX binding sites were within coding regions of genes. GHPA demonstrated significantly increased expression of MAX protein compared to NFPA.
GHPA have significantly different DNA methylation and downstream protein expression levels of MAX compared to NFPA. These differences may influence mechanisms involved with cellular proliferation, tumor invasion and hormonal secretion.
Journal Article
Integrated Genomic Characterization Reveals Novel, Therapeutically Relevant Drug Targets in FGFR and EGFR Pathways in Sporadic Intrahepatic Cholangiocarcinoma
by
Christoforides, Alexis
,
Placek, Pamela
,
Craig, David W.
in
Analysis
,
Antimitotic agents
,
Antineoplastic agents
2014
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.
Journal Article
Making cancer research more inclusive
2021
We have been aware for some time that cancer research, from careers to clinical trials, is not as inclusive as it should be. The Black Lives Matter movement and protests against racism have emphasized that the time has come to stop talking about the lack of diversity, health inequities and structural racism in cancer research and instead work towards solutions. In that spirit, and on the basis of a virtual discussion during the American Association for Cancer Research 2020 Annual Meeting, we asked several scientists actively working to increase representation of Black American populations in cancer research how they are addressing these issues.Based on a virtual discussion during the American Association for Cancer Research (AACR) 2020 Annual Meeting, we asked several scientists actively working to improve representation of Black American populations in cancer research how they are addressing these issues.
Journal Article
Resolving spatial subclonal genomic heterogeneity of loss of heterozygosity and extrachromosomal DNA in gliomas
2025
Mapping the spatial organization of DNA-level somatic copy number changes in tumors can provide insight to understanding higher-level molecular and cellular processes that drive pathogenesis. We describe an integrated framework of spatial transcriptomics, tumor/normal DNA sequencing, and bulk RNA sequencing to identify shared and distinct characteristics of an initial cohort of eleven gliomas of varied pathology and a replication cohort of six high-grade glioblastomas. We identify focally amplified extrachromosomal DNA (ecDNA) in four of the eleven initial gliomas, with subclonal tumor heterogeneity in two
EGFR
-amplified grade IV glioblastomas. In a
TP53
-mutated glioblastoma, we detect a subclone with
EGFR
amplification on ecDNA coupled to chromosome 17 loss of heterozygosity. To validate subclonal somatic aneuploidy and copy number alterations associated with ecDNA double minutes, we examine the replication cohort, identifying
MDM2/MDM4
ecDNA subclones in two glioblastomas. The spatial heterogeneity of
EGFR
and p53 inactivation underscores the role of ecDNA in enabling rapid oncogene amplification and enhancing tumor adaptability under selective pressure.
Currently, there is limited knowledge about the spatial heterogeneity of glioma-driving molecular events. Here, the authors employ a multiomics approach to characterize the spatial transcriptomic heterogeneity of various types of gliomas and identify spatially distinct tumor subclones with genomic plasticity driven by mutations on extrachromosomal DNA.
Journal Article
A transforming mutation in the pleckstrin homology domain of AKT1 in cancer
by
Blanchard, Kerry L.
,
Donoho, Gregory P.
,
Touchman, Jeffrey
in
Amino acids
,
Animals
,
Binding sites
2007
Although AKT1 (v-akt murine thymoma viral oncogene homologue 1) kinase is a central member of possibly the most frequently activated proliferation and survival pathway in cancer, mutation of AKT1 has not been widely reported. Here we report the identification of a somatic mutation in human breast, colorectal and ovarian cancers that results in a glutamic acid to lysine substitution at amino acid 17 (E17K) in the lipid-binding pocket of AKT1. Lys 17 alters the electrostatic interactions of the pocket and forms new hydrogen bonds with a phosphoinositide ligand. This mutation activates AKT1 by means of pathological localization to the plasma membrane, stimulates downstream signalling, transforms cells and induces leukaemia in mice. This mechanism indicates a direct role of AKT1 in human cancer, and adds to the known genetic alterations that promote oncogenesis through the phosphatidylinositol-3-OH kinase/AKT pathway. Furthermore, the E17K substitution decreases the sensitivity to an allosteric kinase inhibitor, so this mutation may have important clinical utility for AKT drug development.
Journal Article
Germline Mutations in HOXB13 and Prostate-Cancer Risk
by
Lange, Ethan M
,
Gielzak, Marta
,
Walsh, Patrick C
in
Biological and medical sciences
,
Chromosome 17
,
Chromosomes, Human, Pair 17
2012
Prostate cancer runs in families. However, the genes that affect the incidence remain largely undefined. The authors have identified a rare germline variant of a homeobox gene,
HOXB13,
in four families with a history of prostate cancer.
Prostate cancer is the most common noncutaneous cancer diagnosed in men in the United States, with more than 240,000 new cases expected in 2011.
1
Despite the demonstration of a strong familial component, identification of the genetic basis for hereditary prostate cancer has been challenging. Linkage studies of families with hereditary prostate cancer have provided inconsistent results.
2
In contrast, genomewide association studies have led to the identification of more than 30 single-nucleotide polymorphisms (SNPs) that are consistently associated with prostate cancer.
3
However, the magnitude of risk elevation attributed to each individual SNP is low, with an increased elevation in risk by . . .
Journal Article
The secreted glycoprotein lubricin protects cartilage surfaces and inhibits synovial cell overgrowth
by
Carpten, John D.
,
Lefebvre, Véronique
,
Marcelino, Jose
in
Animals
,
Biomedical research
,
Cartilage
2005
The long-term integrity of an articulating joint is dependent upon the nourishment of its cartilage component and the protection of the cartilage surface from friction-induced wear. Loss-of-function mutations in lubricin (a secreted glycoprotein encoded by the gene PRG4) cause the human autosomal recessive disorder camptodactyly-arthropathy-coxa vara-pericarditis syndrome (CACP). A major feature of CACP is precocious joint failure. In order to delineate the mechanism by which lubricin protects joints, we studied the expression of Prg4 mRNA during mouse joint development, and we created lubricin-mutant mice. Prg4 began to be expressed in surface chondrocytes and synoviocytes after joint cavitation had occurred and remained strongly expressed by these cells postnatally. Mice lacking lubricin were viable and fertile. In the newborn period, their joints appeared normal. As the mice aged, we observed abnormal protein deposits on the cartilage surface and disappearance of underlying superficial zone chondrocytes. In addition to cartilage surface changes and subsequent cartilage deterioration, intimal cells in the synovium surrounding the joint space became hyperplastic, which further contributed to joint failure. Purified or recombinant lubricin inhibited the growth of these synoviocytes in vitro. Tendon and tendon sheath involvement was present in the ankle joints, where morphologic changes and abnormal calcification of these structures were observed. We conclude that lubricin has multiple functions in articulating joints and tendons that include the protection of surfaces and the control of synovial cell growth.
Journal Article