Discovery Of Oncogenes Research Articles

Medical marvels The 100 greatest advances in medicine

Eugene Straus, professor emeritus of medicine at the State University of New York Health Science Center, has followed up his interesting biography, Rosalyn Yalow, Nobel laureate: her life and work in medicine (1), with Medical marvels: the 100 greatest advances in medicine. Coauthored with journalist Alex Straus, with interesting and stimulating black-and-white illustrations by Bette Korman, the volume examines the science and art of many key medical advances throughout history, selected based on the criteria that they changed the course of medicine, relieved suffering, furthered our understanding of health and disease, and culminated in improvements in disease prevention, diagnosis, or therapeusis. Each of the 100 advances is described concisely within individual 3- to 5-page chapters, thus serving as a launching pad for the reader to acquire additional information on specific topics of interest. Naturally, the breakthroughs that most scientists, physicians, and lay readers will be familiar with appear. These include the discovery of viruses, oncogenes, antibiotics, and stem cells; smallpox vaccination; gene therapy; and, of course Watson, Crick, Wilkins, and Franklin’s identification of the structure of DNA and the elucidation of the human genetic code, regarded as the most important biological experiments in history. The authors also examine the evolution of some of the experimental and diagnostic approaches that researchers and physicians have come to rely on daily, including: history taking and the physical exam, surgical anesthesia, tissue culture, the x-ray, the ECG, and PCR. The authors revisit Antonie van Leeuwenhoek’s construction of the single-lens microscope and William Beaumont’s examination via a perforation in the anterior wall of the stomach of a patient following a shotgun wound, which provided the earliest insights into the digestive process and its regulation in vivo. This led to the work of Ivan Pavlov, whose experiments with dogs provided great insight into the mechanisms of salivation, pancreatic function, hunger, and satiation and identified the phenomenon now known as classical conditioning. As an additional resource, the authors include as part of their discussion of solid organ transplantation contact information for national organizations that assist patients in need of transplants. In the 1940s, as a naval medical corpsman, I had the great fortune to be among the first to administer a new drug — penicillin — to casualties from the Pacific Island invasions. At that time the results obtained from using penicillin were astounding and never before equaled by any therapeutic agent for infections. Alexander Fleming and Howard Florey’s work toward the discovery and commercial production of penicillin rightly appears on Straus’s list, and this drug represents a true medical marvel. Throughout the text each chapter is admixed with others concerned with social and economic problems associated with socialized medicine, medical ethics, health maintenance organizations, patient advocacy, and related subjects. These include the evolution of the doctor-patient relationship into one of a provider and customer, the management of addictive behavior, and the underrepresentation of minorities and women in the pursuit of medicine. As interesting and important as the sections on the social aspects of medicine are, they distract from the flow of scientific information and would have better constituted a separate section of the book. This is not to diminish the importance of these sections, but rather to note that they interrupt the sequence of summaries of medical research–related accomplishments. Based on my own experience in medicine and research since 1953, I would have included several additional advances in the physical sciences, akin to some of those highlighted by John Gribbin in The scientists: a history of science told through the lives of its greatest inventors (2), along with the elucidation of the structure of the psychotropic serum vasoconstrictor serotonin and the research of Erwin Chargaff that actually laid the groundwork for the discovery of the double-helix structure of DNA. I would hope to see these featured if a second edition of this volume is released. Thus, we have an interesting, richly illustrated book for both the layman and scientist who wish to develop broad baseline information on major medical advances. However, more than simply a compendium of breakthroughs in medical technology, Medical marvels intertwines the social and ethical aspects of the practice of medicine with the science, impressing upon the reader the dedication of individuals committed to enhancing the quality of human life. The text is strongly recommended as interesting, informative, and stimulating reading.

The impact of genomic alterations on the transcriptome: a prostate cancer cell line case study

Genetic instability may lead to the loss/gain of transcriptional control. Here we investigated the effect of genomic instability, that is loss/gain of chromosomal regions on the global transcriptome of prostate cancer cell line DU145. The genomic loss/gain map obtained through BAC array-based CGH was superimposed on the dynamic transcriptome of DU145 cells treated with serum for 0 h (serum starved), 2 h and 12 h. The genomic analysis suggested that in DU145 cells: (1) chromosomal gains are prominent than losses and (2) copy number changes are associated with chromosome-specific and dynamic gene expression regulatory mechanisms. A significant proportion of the genes in the stable regions of the chromosome were up-regulated whereas a higher proportion of genes were down-regulated at 2 and 12 h in the deleted regions of the chromosomes following serum treatment. No change in expression was observed for the genes in the gained regions over a period of time. This analysis led us to propose that loss of heterozygosity leads to an overall transcriptional down-regulation that may further lead to a decrease in the expression of putative tumor suppressors. The genomic profile of DU145 is similar to pathological specimens of prostate cancer, hence the genomic/transcriptomic signature of DU145 can be used to understand the pathology of prostate cancer. It is expected that this analysis will allow a better understanding of transcriptional regulatory mechanisms in the context of genomic loss and gain and may lead to the discovery of novel oncogenes and tumor suppressors and the underlying regulatory pathways.

Recent translational research: Oncogene discovery by insertional mutagenesis gets a new boost

Knowledge of the genes and genetic pathways involved in onco-genesis is essential if we are to identify novel targets for cancer therapy. Insertional mutagenesis in mouse models is among the most efficient tools to detect novel cancer genes. Retrovirus-mediated insertional mutagenesis received a tremendous boost by the availability of the mouse genome sequence and new PCR methods. Application of such advances were limited to lympho-magenesis but are now also being applied to mammary tumourigenesis. Novel transposons that allow insertional muta-genesis studies to be conducted in tumors of any mouse tissue may give cancer gene discovery a further boost.

Functional and physical communication between oncoproteins and tumor suppressors.

The discovery of oncogenes (c-onc's) and tumor suppressors (TS's) has led to the concept that cancer arises from defects in each of these classes of genes or their products. More recently, it has been appreciated that c-onc and TS proteins often affect one another's functions. Within this context, I review the two classical TS's, p53 and the retinoblastoma protein, and the consequences of their inactivation. The various forms of genomic instability (GI) that underly the high mutation rates of transformed cells are then discussed. Particular emphasis is placed upon the concept that GI is not only an integral part of the transformed state but is a prerequisite. Increased oxidative DNA damage, and/or an inabiliy to repair it, can lead to GI. The review then discusses recent observations showing that loss of the TS protein peroxiredoxin 1 (prdx 1) and increased expression of the c-onc protein c-Myc, each leads to increased oxidative DNA damage. The critical nature of the c-onc-TS interaction is underscored by that occurring between prdx1 and c-Myc, with the former protein regulating the production of DNA-damaging reactive oxygen species by the latter. The intimate association between these proteins and others serves as a paradigm for the exquisite balancing act that c-onc's and TS's must maintain in order to properly control normal DNA replication and cellular proliferation while simultaneously minimizing the acquisition of potentially neoplastic mutations.

Getting at MYC through RAS

The discovery of oncogenes provided insight into the molecular underpinnings of cancer and suggested the promise of novel molecular strategies for cancer treatment as highlighted in this issue by Yaari et al. and by Bishop previously ([1][1], [2][2]). However, only recently have effective drugs that

Genetic changes in localized prostate cancer of Japanese patients shown by comparative genomic hybridization

To search for additional amplification and deletion sites that may serve as a starting point for the discovery of new oncogenes or tumor suppressor genes, 30 Japanese localized prostate cancers were analyzed by comparative genomic hybridization (CGH) in this study. CGH was used to search for changes in DNA sequence copy-number in a series of 30 primary prostate adenocarcinomas, consisting of 22 cases of pT2N0 (organ confined; without capsular invasion) and 8 cases of pT3N0 (with capsular invasion), removed by radical prostatectomy. CGH revealed that the shortest regions of overlap (SRO) of gains in pT2N0 were at 8q22.2∼q24.2, 11q13.1∼q14.1, and 12q23∼q24.2, whereas the SRO of losses were seen at 8p23.3∼p22, 13q21.2∼p22, and 18q21∼q22. The SRO of gains in pT3N0 were noted at 5q32∼q34, 8q22.3∼q24.1, 11q14.1∼q22.3, and 12q22∼q24.2, whereas the SRO of losses were seen at 18q21.2∼q23. These results suggest that gains or losses of DNA in these regions are important for prostate cancer progression. The detection of the SRO may serve as a starting point to discover novel oncogenes and tumor suppressor genes involved in prostate cancer progression.

Seven Novel and Stable Translocations Associated with Oncogenic Gene Expression in Malignant Melanoma

Cytogenetics has not only precipitated the discovery of several oncogenes, but has also led to the molecular classification of numerous malignancies. The correct identification of aberrations in many tumors has, however, been hindered by extensive tumor complexity and the limitations of molecular cytogenetic techniques. In this study, we have investigated five malignant melanoma (MM) cell lines from at least three different passages using high-resolution R-banding and the recently developed methods of comparative genomic hybridization and multicolor or multiplex fluorescence in situ hybridization. We subsequently detected nine consistent translocations, seven of which were novel: dic(1;11)(p10;q14), der(9)t(3;9)(p12;p11), der(4)t(9;4;7)(q33::p15-q23::q21), der(14)t(5;14) (q12;q32), der(9)t(9;22)(p21;q11), der(19)t(19;20)(p13.3;p11), der(10)t(2;12;7;10)(q31::p12→pter::q11.2→q31::q21),der(19)t(10;19)(q23;q13), and der(20)t(Y;20)(q11.23;q13.3). Furthermore, using the human HG-U133A Gene-Chip, positive expression levels of oncogenes or tumor-related genes located at the regions of chromosomal breakpoints were identified, including AKT1, BMI1, CDK6, CTNNB1, E2F1, GPNMB, GPRK7, KBRAS2, LDB2, LIMK1, MAPK1, MEL, MP1, MUC18, NRCAM, PBX3, RAB22A, RAB38, SNK, and STK4, indicating an association between chromosomal breakpoints and altered gene expression. Moreover, we also show that growth of all five cell lines can be significantly reduced by downregulating CDK6 gene expression with small interfering RNA (siRNA). Because the majority of these breakpoints have been reported previously in MM, our results support the idea of commonmechanisms in this disease.

Oncogenes as Novel Targets for Cancer Therapy (Part I)

In the past 10 years, progress made in cancer biology, genetics, and biotechnology has led to a major transition in cancer drug design and development. There has been a change from an emphasis on non-specific, cytotoxic agents to specific, molecular-based therapeutics. Mechanism-based therapy is designed to act on cellular and molecular targets that are causally involved in the formation, growth, and progression of human cancers. These agents, which may have greater selectivity for cancer versus normal cells, and which may produce better anti-tumor efficacy and lower host toxicity, can be small molecules, natural or engineered peptides, proteins, antibodies, or synthetic nucleic acids (e.g. antisense oligonucleotides, ribozymes, and siRNAs). Novel targets are identified and validated by state-of-the-art approaches, including high-throughput screening, combinatorial chemistry, and gene expression arrays, which increase the speed and efficiency of drug discovery and development. Examples of oncogene-based, molecular therapeutics that show promising clinical activity include trastuzumab (Herceptin), imatinib (Gleevec), and gefitinib (Iressa). However, the full potential of oncogenes as novel targets for cancer therapy has not been realized and many challenges remain, from the validation of novel targets, to the design of specific agents, to the evaluation of these agents in both preclinical and clinical settings. In maximizing the benefits of molecular therapeutics in monotherapy or combination therapy of cancer, it is necessary to have an understanding of the underlying molecular abnormalities and mechanisms involved. This is the first part of a four-part review in which we discuss progress made in the last decade as it relates to the discovery of novel oncogenes and signal transduction pathways, in the context of their potential as targets for cancer therapy. This part delineates the latest discoveries about the potential use of growth factors and protein tyrosine kinases as targets for therapy. Later parts focus on intermediate signaling pathways, transcription factors, and proteins involved in cell cycle, DNA damage, and apoptotic pathways.

SynMuv verité—Myb comes into focus: Figure 1.

Over the past 25 years, tremendous progress has been made in the identification of the genetic alterations that cause cancer. The discovery of oncogenes and tumorsuppressor genes relied largely on studies of animal retroviruses, consistent chromosomal aberrations in human cancers, transfection of human tumor DNA into rodent cells, DNA tumor viruses, and rare familial cancer syndromes (Bishop 1995). A major challenge has been to understand the function of the protein products of these genes in both normal and malignant cells. In many cases studies of developmental genetics in model organisms have provided key insights that have illuminated the pathways that go awry in human cancer. In particular, the awesome power of beast genetics in the nematode and fruit fly has benefited from the speed and rela

More Than One Mutation Is Required for Leukemia Development Following Retroviral Vector-Mediated Gene Transfer.

As recent case reports have suggested that proto-oncogene activation by replication-deficient retroviral vectors may trigger leukemia in mice and men, there is an urgent need for models allowing predictive investigations into the pathomechanisms of this complication. Previously, we have shown that dose-escalated replication-defective retrovirus vectors (such as HaMDR1 or SF91dsRedpre) may trigger combinatorial leukemia-initiating events in single cells, with a probability that allows prospective studies in simple mouse models (C57Bl/6). Meanwhile, we have performed molecular analyses for 5 different leukemias, harboring 6 to 12 vector insertions according to Southern blot. 34 insertions recovered from these clones by LM-PCR and LAM-PCR showed that 4 leukemias had combinatorial hits in at least one established proto-oncogene (class 1 genes: Hivep1, Mllt3, Fli1, HoxA7, Brd2, Evi1, Csfr3, Bcl11a, Ski) with at least one hit in other signaling genes (class 2 genes). One leukemia for which 2 insertions remain to be identified showed at least 3 class 2 hits, so far without a class 1 event. All leukemias presented with hits in genes involved in cytoplasmic signal cascades along with genes contributing to nuclear regulatory networks. Some of these leukemias had a normal karyotype. A comparison with 62 insertion sites from healthy control animals (determined in peripheral blood DNA harvested 7 months after transplantation) revealed a significant enrichment of class 1 hits in leukemias (14-fold over expected and 3-fold over control). Healthy animals still showed 6 hits (~10%) in class 1 genes, obviously not being sufficient for leukemia induction. Three of these occurred upstream of Evi1, one upstream of Nfic, one upstream of Pdclg2, and one in Bcl11a. Interestingly, upstream vector insertion was preferred in class 1 gene hits. Overall, insertions recovered from both normal and leukemic samples revealed an overrepresentation of hits within (or upstream of) known or predicted genes (89 and 90%, respectively). In line with the data of a related murine marking study (Kustikova, Fehse et al., ASH 2004), our study strongly suggests that single hits in class 1 or class 2 genes are not sufficient to induce leukemia in mice. However, certain combinations of such events in single cells may well be leukemogenic with a given latency. Our findings establish a powerful approach for both oncogene discovery and safety validation in gene therapy.

Comprehensive Genome-Wide Profile of Regional Gains and Losses in Multiple Myeloma Using Array-CGH: The 1q21 Amplification and Potential Role of the BCL-9 Gene in Multiple Myeloma Pathogenesis.

Multiple Myeloma (MM) is characterized by a clonal proliferation of abnormal plasma cells in the bone marrow and is among the most frequent and lethal hematological diseases. In spite of significant effort towards the identification of the molecular events leading to this malignancy, the genetic alterations responsible for the pathogenesis of this disease remain poorly understood. Regional copy number alterations (CNAs) in cancer genomes have been among the most informative structural changes in cancer and have led to the discovery of many oncogenes and tumor supressor genes. Using array comparative genomic hybridization (array-CGH) and expression microarray technologies we have analyzed a large collection of cell lines and clinically annotated primary tumors. This high-resolution genomic analysis has identified all previously reported regional gains and losses as well as many novel highly recurrent genetic loci with potential biological and clinical relevance. In particular, we have identified an amplification at chromosome 1q21 as one of the most recurrent genetic changes in cell lines and in a subgroup of primary tumors. This chromosomal change has been previously implicated with disease progression. Analysis across several cell lines has allowed the identification of a Minimal Common Region (MCRs) of amplification at 1q21. Correlation between DNA copy number changes and expression profiling data has identified a limited set of candidate genes within this MCR that are amplified and overexpressed. Using shRNAi technology we have identified BCL-9 as a candidate gene residing at the 1q21 MCR. In vitro and in vivo functional data about the role of BL-9 will be presented. These data will provide critical understanding on the diverse pathways leading to Multiple Myeloma progression.

Abnormal constitutional karyotypes in patients with neuroblastoma: a report of four new cases and review of 47 others in the literature

Anomalies of constitutional karyotype, which have led to the discovery of oncogenes and tumor-suppressor genes in embryonal tumors such as retinoblastoma and Wilms tumor, have, until recently, rarely been reported until recently in neuroblastoma. We present four new cases of neuroblastoma associated with (a) a mosaicism for monosomy 22; (b) an 11q interstitial deletion; (c) a pericentric inversion of chromosome 9 at band 9p21; and (d) a Robertsonian translocation t(13;14). These anomalies and 47 others in the literature are worthy of interest, because some are recurrent, involving the same chromosome regions (1p36, 2p23, 3q, 11q23, and 15q), and some anomalies are situated on chromosome regions known to contain genes involved in neuroblastoma development (1p, 2p, 9p, 11q, 16q, and 17q). Chromosome regions 3q and 15q, observed several times, may also contain genes significant for neuroblastoma onset or development. Furthermore, the lack of neuroblastoma in patients with Down syndrome and Klinefelter or triple-X syndromes, together with a probable excess of neuroblastoma in patients with Turner syndrome, suggests that genes of importance for neuroblastoma may map to chromosomes X and 21. A search for genes implicated in neuroblastoma biology should use these data.

Treatment by design in leukemia, a meeting report, Philadelphia, Pennsylvania, December 2002.

Novel approaches have been designed to treat leukemia based on our understanding of the genetic and biochemical lesions present in different malignancies. This meeting report summarizes some of the recent advances in leukemia treatment. Based on the discoveries of cellular oncogenes, chromosomal translocations, monoclonal antibodies, multidrug resistance pumps, signal transduction pathways, genomics/proteonomic approaches to clinical diagnosis and mutations in biochemical pathways, clinicians and basic scientists have been able to identify the particular genetic mutations and signal transduction pathways involved as well as design more appropriate treatments for the leukemia patient. This meeting report discusses these exciting new therapies and the results obtained from ongoing clinical trials. Furthermore, rational approaches to treat complications of tumor lysis syndrome by administration of the recombinant urate oxidase protein, also known as rasburicase, which corrects the biochemical defect present in humans, were discussed. Clearly, over the past 25 years, molecular biology and biotechnology has provided the hematologist/oncologist novel bullets in their arsenal that will allow treatment by design in leukemia.

A screen to identify drug resistant variants to target-directed anti-cancer agents.

The discovery of oncogenes and signal transduction pathways important for mitogenesis has triggered the development of target-specific small molecule anti-cancer compounds. As exemplified by imatinib (Gleevec), a specific inhibitor of the Chronic Myeloid Leukemia (CML)-associated Bcr-Abl kinase, these agents promise impressive activity in clinical trials, with low levels of clinical toxicity. However, such therapy is susceptible to the emergence of drug resistance due to amino acid substitutions in the target protein. Defining the spectrum of such mutations is important for patient monitoring and the design of next-generation inhibitors. Using imatinib and BCR/ABL as a paradigm for a drug-target pair, we recently reported a retroviral vector-based screening strategy to identify the spectrum of resistance-conferring mutations. Here we provide a detailed methodology for the screen, which can be generally applied to any drug-target pair.

Emerging opportunities and career paths for the young physician-scientist.

1‐3 . Physician-scientists are vital members of the medical research enterprise, because the scientific questions they ask reflect the experiences they gain from taking care of sick people. This generalization can be illustrated by listing some of their notable achievements, such as the discovery of oncogenes, the low-density lipoprotein receptor, prions, HIV, pulmonary surfactant, and the defective genes in many inherited disorders; the eradication of smallpox and the near-eradication of polio; cures for childhood leukemia, Hodgkin disease, and testicular cancer; the development of open-heart surgery, of organ and bone-marrow transplantation, and of approaches to decrease mortality after heart attacks and strokes. The kinds of questions that physicianscientists tend to ask will become even more important as information about the human genome swells in this ‘post-genomic’ era. They are also in an ideal position to communicate and collaborate, both with PhD scientists and with health-care providers. Finally, physician-scientists can make the strongest case for the medical relevance of basic research to legislators, advocates and health agencies 4

Elements of signal transduction in drug discovery with special reference to inhibitors of protein kinase C.

Although for a few malignancies, such as childhood leukaemia, Hodgkin’s disease, and testicular cancer, impressive progress has been achieved, cancer mortality as a whole has remained almost unchanged during the last two decades despite enormous worldwide efforts. This is particularly surprising in view of the tremendous progress that has been achieved during the last 20–25 years with regard to our understanding of the molecular mechanisms underlying the regulation of normal growth and dysregulation of malignant growth. Major scientific breakthroughs — the discovery of oncogenes, tumour suppressor genes, mechanisms of angiogenesis, and apoptosis — have occurred during the last two to three decades, but these have not led to any major progress in cancer treatment.

Ets and retroviruses - transduction and activation of members of the Ets oncogene family in viral oncogenesis.

Studies of retroviral-induced oncogenesis in animal systems led to the initial discovery of viral oncogenes and their cellular homologs, and provided critical insights into their role in the neoplastic process. V-ets, the founding member of the ETS oncogene family, was originally identified as part of the fusion oncogene encoded by the avian acute leukemia virus E26 and subsequent analysis of virus induced leukemias led to the initial isolation of two other members of the ETS gene family. PU.1 was identified as a target of insertional activation in the majority of tumors induced by the murine Spleen Focus Forming virus (SFFV), while fli-1 proved to be the target of Friend murine leukemia virus (F-MuLV) in F-MuLV induced erythroleukemia, as well as that of the 10A1 and Graffi viruses. The common features of the erythroid and myeloid diseases induced by these viruses provided the initial demonstration that these and other members of the ETS family play important roles in hematopoietic development as well as disease. This review provides an overview of the role of ETS genes in retrovirally induced neoplasia, their possible mechanisms of action, and how these viral studies relate to current knowledge of the functions of these genes in hematopoiesis.

Proliferative and apoptotic responses in cancers with special reference to oral cancer.

The study of signal transduction pathways for mechanisms of apoptosis and proliferation has significantly advanced our understanding of human cancer, subsequently leading to more effective treatments. Discoveries of growth factors and oncogenes, especially those that function through phosphorylation on tyrosine residues, have greatly benefited our appreciation of the biology of cancer. The regulation of proliferation and apoptosis through phosphorylation via tyrosine kinases and phosphatases is discussed, as well as the contributions of other systems, such as serine and threonine kinases and phosphatases. Receptors with seven-transmembrane domains, steroid hormones, genes, and "death domains" will also be discussed. This review attempts to compare the regulation of the growth of normal tissues and cancers with an effort to highlight the current knowledge of these factors in the growth regulation of oral/oropharyngeal cancers. Despite the strides made in our understanding of growth regulation in human cancers, the study of oral/oropharyngeal cancer specifically lags behind. More research must be done to further our understanding of oral cancer biology, if we are to develop better, more effective treatment protocols.

TELOMERASE: THE ACHILLES' HEEL OF CANCER?

In the past 20 years, the discovery of oncogenes and tumor-suppressor genes has revolutionized cancer biology and directly affected clinical practice.

TELOMERASE: THE ACHILLES' HEEL OF CANCER?

In the past 20 years, the discovery of oncogenes and tumor-suppressor genes has revolutionized cancer biology and directly affected clinical practice.