DOCSLIB.ORG

Alterations of the P16 Gene in Head and Neck Cancer: Frequency and Association with P53, PRAD-1 and HPV

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Alterations of the P16 Gene in Head and Neck Cancer: Frequency and Association with P53, PRAD-1 and HPV Oncogene (1997) 14, 811 ± 818 1997 Stockton Press All rights reserved 0950 ± 9232/97 $12.00 Alterations of the p16 gene in head and neck cancer: frequency and association with p53, PRAD-1 and HPV Andrew F Olshan1,2, Mark C Weissler2, Hong Pei1, Kathleen Conway1, Steven Anderson3, Daniel B Fried1 and Wendell G Yarbrough2 1Department of Epidemiology, School of Public Health, University of North Carolina, Chapel Hill, North Carolina; 2Division of Otolaryngology/Head and Neck Surgery, School of Medicine, University of North Carolina, Chapel Hill, North Carolina; 3Department of Molecular Biology and Pathology, Laboratory Corporation of America, Research Triangle Park, North Carolina, USA Alterations, especially homozygous deletions, of the suppressor gene (Brachman, 1994). Recently, the putative tumor suppressor gene, p16 (p16INK4A, MTS1, cyclin-dependent kinase inhibitor, p16 (p16INK4A, CDKN2) have been found in tumor cell lines from a MTS1, CDKN2), has been proposed as the tumor variety of neoplasms. Recent studies have reported suppressor gene at 9p21 (Serrano et al., 1993, 1996; frequent p16 gene deletions in cell lines from squamous Kamb et al., 1994; Nobori et al., 1994; Lukas et al., cell carcinomas of the head and neck (SCCHN), 1995a; Koh et al., 1995; Spillare et al., 1996). Related although the prevalence of alterations was variable in CDK-inhibitors have also been isolated including primary tumors. This study determined the prevalence of p15INK4b, p18INK4C and p19INK4d (Sherr and Roberts, point mutations and deletions of the p16 gene in 33 1995). Further, the p16INK4a locus yields two transcripts SCCHN. In addition, the association of p16 gene one encoding p16INK4a and another encoding p19ARF alterations and abnormalities of p53, PRAD-1 (cyclin (Quelle et al., 1995). All of these genes participate D1), and the presence of human papillomavirus (HPV) either directly or indirectly in the control of the cell was examined. We found an overall prevalence of p16 cycle. alterations of 36% (nine deletions, three single base The transition from G1 to S in the cell cycle relies on substitutions, including one polymorphism). Seven tumors a coordinated interaction of several gene products (of 29, 24%) had an alteration of p16 and p53; ®ve (of including the retinoblastoma protein (Rb), cyclin D1, 33, 15%) had alterations of p16 and PRAD-1; three (of and its catalytic partners CDK4 and CDK6, and the 29, 10%) had alterations of all three genes. In addition, cyclin-dependent kinase inhibitor, p16 (Peter and of the ®ve tumors with human papillomavirus detected, Herskowitz, 1994; Grana and Reddy, 1995; Yeudall only one also had a p16 gene alteration. The results and Jakus, 1995). Loss of control of the G1 to S indicate a potentially important role for the p16 gene in transition is a common defect observed in many head and neck tumorigenesis. In addition, the presence of dierent tumor types and can occur through a variety tumors with multiple somatic gene alterations suggest a of mechanisms (Hartwell and Kastan, 1994; Kamb, possible interaction in the dysregulation of the cell cycle. 1995). Viruses that are associated with tumors, such as the human papillomavirus (HPV) and SV40, produce Keywords: head and neck neoplasms; mutation; p53; proteins that inactivate Rb and p53. Also, mutations p16INKA4; HPV; PRAD-1 and/or deletions of RB, p53, and p16 and ampli®cation and overexpression of cyclin D1 are relatively common events in a wide range of tumors. Recently, evidence for transcriptional repression of p16 through promotor Introduction methylation has been observed in all major solid tumor types, suggesting another mechanism through which Squamous cell carcinoma of the head and neck loss of control of the G1-S transition can occur (Merlo (SCCHN, including oral cavity, pharynx and larynx) et al., 1995). It has been suggested that dierent genes provides an excellent model for understanding the related to the control of the cell cycle represent carcinogenic process due to the de®ned risk factors alternate targets and that functionally inactivating (tobacco and alcohol consumption) and emerging any one component will have the same consequence molecular characteristics. Cytogenetic, allelotyping, of loss of cell cycle control. Little research has been loss of heterozygosity, and gene ampli®cation studies done to evaluate alternate pathways by examining the have implicated 11q as the site of a putative oncogene, interrelationship among abnormalities in cell cycle and 17p, 9p and 3p as sites of putative tumor genes in tumors. The relationship betwen p16 and suppressor genes in SCCHN (Cowan et al., 1992; other genes, including HPV has not been directly Nawroz et al., 1994; Van der Reit et al., 1994). investigated in SCCHN. Molecular studies have identi®ed candidate genes for Examination of primary tumors and cell lines for these regions, namely cyclin D1 (PRAD-1, CCND1) as alterations of the p16 gene has yielded con¯icting the protooncogene and p53 as a putative tumor results. Initial reports indicated a high frequency of homozygous deletions of p16 in a variety of cell lines (Kamb et al., 1994; Nobori et al., 1994). In addition, Correspondence: AF Olshan point mutations were identi®ed in cell lines without Received 14 June 1996; revised 18 October 1996; accepted 18 October deletions. Other studies using primary tumors reported 1996 a much lower prevalence of p16 deletions and p16 gene alterations and head and neck cancer A F Olshan et al 812 mutations, suggesting that tumor cells might acquire a p16 defects as a consequence of forming established 12345678 lines (Carins et al., 1994; Spruck et al., 1994). More GAPDH recent studies suggest that p16 defects are not an p16 artifact of establishing cell lines because they occur in a high percentage of certain types of primary carcinomas (Mori et al., 1994; Zhou et al., 1994; Caldas et al., p16 1994; Schmidt et al., 1994; Carins et al., 1995). Two CPT analyses of primary head and neck tumors have reported a prevalence of point mutations of 7% and 10%, con®rming that the loss of p16 function more commonly occurs through deletion (Carins et al., 1994; Zhang et al., 1994). Two recent reports indicated a b higher prevalence of p16 gene alterations in head and 123456 neck tumors 25% (16/65; all deletions; Carins et al., GAPDH 1995) and 19% (7/36; six deletions; Lydiatt et al., p16 1995). None of the studies of SCCHN evaluated the relationship between p16 gene alterations and the p16 presence of alterations of other cell cycle associated CPT genes. In this study, we determined the prevalence of p16 0 20 40 60 80 100 somatic alterations in 33 SCCHN tumors and have % Normal DNA examined the association of p16 mutation or deletion Figure 1 Representative deletion analysis of p16 gene in head with aberrations of other tumor suppressor genes and and neck tumors. (a), PCR products from six tumors and two oncogenes, and with the presence of human papillo- control samples with two reference genes, GAPDH and CPT. mavirus (HPV). Our results provide additional Lanes 2, 4, 5, deletions of the p16 target gene. Lane 7, sample of normal tonsil tissue. Lane 8, cell line with p16 homozygous evidence for the role of the inactivation of p16 in the deletion (K562). The estimated percentage of contaminating development of head and neck cancer. normal cells and ratio of the intensity of the target gene band to the reference gene (CPT) was: lane 1 (70%, 1.04), 2 (25%, 0.24), 3 (60%, 1.03), 4 (70%, 0.64), 5 (60%, 0.63), 6 (60%, 1.05), 7 (100%, 1.00), 8 (0%, 0.00). (b) Comparison PCR using a mixed Results DNA template from human foreskin ®broblast and a human leukemia cell line (K562) with a known homozygous deletion of Among the 33 tumors examined, a total of 12 (36%) the p16 gene and GAPDH and CPT as reference genes. The had either a deletion (n=9) or single base substitution percentage of normal DNA mixed in the template is shown at the in exon 2 of the p16 gene (n=3). Using dierential bottom of the lanes. The ratio of the intensity of the target gene band to the reference gene (CPT) band for each sample was: lane PCR, independently coampli®ed each time with a 1 (0.00), 2 (0.31), 3 (0.53), 4 (0.69), 5 (0.78), 6 (1.01) dierent set of reference genes (PGR/d-IFN, GAPDH/CPT), we detected p16 deletions in 9 (27%) of the tumors (Figure 1 and Table 1). Figure 2 shows an example of selected mutations. tumors had a p16 base change, did not show any p16 Four mutations were identi®ed in three tumors mutations or deletions. Although there were some including an A4T transversion (GAC4GTC, dierences, no signi®cant association was found Asp4Val) at codon 76 (case #2300), a G4A between the presence of a p16 mutation and SCCHN transition (GCG4ACG, Ala4Thr) at codon 140 site (P=0.74), recurrence status (P=0.43), or history (case #4165), and a tumor (case #3515) with two of preoperative radio- or chemotherapy (P=0.42). G4T transversion mutations, one at codon 79 Additionally, there was no relation between p16 (CGG4CTG, Arg4Leu), the other at codon 80 alterations and Tumor-Node-Metastasis (TNM) stage (GAG4TAG, Glu4Stop). Mutations at codon 76 classi®cation (P=0.47). have been reported in a previous study of head and We were also able to successfully screen 29 of the 33 neck tumors and in a study of esophageal cancer SCCHN tumors for p53 mutations using SSCP and (Spruck et al., 1994; Mori et al., 1994). In both cases, direct sequencing. Twelve of 29 (41%) tumors were the sequence change was a transition from GAC to found to have a mutation of the p53 gene and seven of AAC; in our study the change was a transversion these 12 also had a p16 alteration (®ve deletions and from GAC to GTC.
Load more

Recommended publications
  • The Retinoblastoma Tumor-Suppressor Gene, the Exception That Proves the Rule
    Oncogene (2006) 25, 5233–5243 & 2006 Nature Publishing Group All rights reserved 0950-9232/06 $30.00 www.nature.com/onc REVIEW The retinoblastoma tumor-suppressor gene, the exception that proves the rule DW Goodrich Department of Pharmacology & Therapeutics, Roswell Park Cancer Institute, Buffalo, NY, USA The retinoblastoma tumor-suppressor gene (Rb1)is transmission of one mutationally inactivated Rb1 allele centrally important in cancer research. Mutational and loss of the remaining wild-type allele in somatic inactivation of Rb1 causes the pediatric cancer retino- retinal cells. Hence hereditary retinoblastoma typically blastoma, while deregulation ofthe pathway in which it has an earlier onset and a greater number of tumor foci functions is common in most types of human cancer. The than sporadic retinoblastoma where both Rb1 alleles Rb1-encoded protein (pRb) is well known as a general cell must be inactivated in somatic retinal cells. To this day, cycle regulator, and this activity is critical for pRb- Rb1 remains an exception among cancer-associated mediated tumor suppression. The main focus of this genes in that its mutation is apparently both necessary review, however, is on more recent evidence demonstrating and sufficient, or at least rate limiting, for the genesis of the existence ofadditional, cell type-specific pRb func- a human cancer. The simple genetics of retinoblastoma tions in cellular differentiation and survival. These has spawned the hope that a complete molecular additional functions are relevant to carcinogenesis sug- understanding of the Rb1-encoded protein (pRb) would gesting that the net effect of Rb1 loss on the behavior of lead to deeper insight into the processes of neoplastic resulting tumors is highly dependent on biological context.
    [Show full text]
  • DNA Microarrays (Gene Chips) and Cancer
    DNA Microarrays (Gene Chips) and Cancer Cancer Education Project University of Rochester DNA Microarrays (Gene Chips) and Cancer http://www.biosci.utexas.edu/graduate/plantbio/images/spot/microarray.jpg http://www.affymetrix.com Part 1 Gene Expression and Cancer Nucleus Proteins DNA RNA Cell membrane All your cells have the same DNA Sperm Embryo Egg Fertilized Egg - Zygote How do cells that have the same DNA (genes) end up having different structures and functions? DNA in the nucleus Genes Different genes are turned on in different cells. DIFFERENTIAL GENE EXPRESSION GENE EXPRESSION (Genes are “on”) Transcription Translation DNA mRNA protein cell structure (Gene) and function Converts the DNA (gene) code into cell structure and function Differential Gene Expression Different genes Different genes are turned on in different cells make different mRNA’s Differential Gene Expression Different genes are turned Different genes Different mRNA’s on in different cells make different mRNA’s make different Proteins An example of differential gene expression White blood cell Stem Cell Platelet Red blood cell Bone marrow stem cells differentiate into specialized blood cells because different genes are expressed during development. Normal Differential Gene Expression Genes mRNA mRNA Expression of different genes results in the cell developing into a red blood cell or a white blood cell Cancer and Differential Gene Expression mRNA Genes But some times….. Mutations can lead to CANCER CELL some genes being Abnormal gene expression more or less may result
    [Show full text]
  • P14ARF Inhibits Human Glioblastoma–Induced Angiogenesis by Upregulating the Expression of TIMP3
    P14ARF inhibits human glioblastoma–induced angiogenesis by upregulating the expression of TIMP3 Abdessamad Zerrouqi, … , Daniel J. Brat, Erwin G. Van Meir J Clin Invest. 2012;122(4):1283-1295. https://doi.org/10.1172/JCI38596. Research Article Oncology Malignant gliomas are the most common and the most lethal primary brain tumors in adults. Among malignant gliomas, 60%–80% show loss of P14ARF tumor suppressor activity due to somatic alterations of the INK4A/ARF genetic locus. The tumor suppressor activity of P14ARF is in part a result of its ability to prevent the degradation of P53 by binding to and sequestering HDM2. However, the subsequent finding of P14ARF loss in conjunction with TP53 gene loss in some tumors suggests the protein may have other P53-independent tumor suppressor functions. Here, we report what we believe to be a novel tumor suppressor function for P14ARF as an inhibitor of tumor-induced angiogenesis. We found that P14ARF mediates antiangiogenic effects by upregulating expression of tissue inhibitor of metalloproteinase–3 (TIMP3) in a P53-independent fashion. Mechanistically, this regulation occurred at the gene transcription level and was controlled by HDM2-SP1 interplay, where P14ARF relieved a dominant negative interaction of HDM2 with SP1. P14ARF-induced expression of TIMP3 inhibited endothelial cell migration and vessel formation in response to angiogenic stimuli produced by cancer cells. The discovery of this angiogenesis regulatory pathway may provide new insights into P53-independent P14ARF tumor-suppressive mechanisms that have implications for the development of novel therapies directed at tumors and other diseases characterized by vascular pathology. Find the latest version: https://jci.me/38596/pdf Research article P14ARF inhibits human glioblastoma–induced angiogenesis by upregulating the expression of TIMP3 Abdessamad Zerrouqi,1 Beata Pyrzynska,1,2 Maria Febbraio,3 Daniel J.
    [Show full text]
  • Review Article PTEN Gene: a Model for Genetic Diseases in Dermatology
    The Scientific World Journal Volume 2012, Article ID 252457, 8 pages The cientificWorldJOURNAL doi:10.1100/2012/252457 Review Article PTEN Gene: A Model for Genetic Diseases in Dermatology Corrado Romano1 and Carmelo Schepis2 1 Unit of Pediatrics and Medical Genetics, I.R.C.C.S. Associazione Oasi Maria Santissima, 94018 Troina, Italy 2 Unit of Dermatology, I.R.C.C.S. Associazione Oasi Maria Santissima, 94018 Troina, Italy Correspondence should be addressed to Carmelo Schepis, [email protected] Received 19 October 2011; Accepted 4 January 2012 Academic Editors: G. Vecchio and H. Zitzelsberger Copyright © 2012 C. Romano and C. Schepis. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. PTEN gene is considered one of the most mutated tumor suppressor genes in human cancer, and it’s likely to become the first one in the near future. Since 1997, its involvement in tumor suppression has smoothly increased, up to the current importance. Germline mutations of PTEN cause the PTEN hamartoma tumor syndrome (PHTS), which include the past-called Cowden, Bannayan- Riley-Ruvalcaba, Proteus, Proteus-like, and Lhermitte-Duclos syndromes. Somatic mutations of PTEN have been observed in glioblastoma, prostate cancer, and brest cancer cell lines, quoting only the first tissues where the involvement has been proven. The negative regulation of cell interactions with the extracellular matrix could be the way PTEN phosphatase acts as a tumor suppressor. PTEN gene plays an essential role in human development. A recent model sees PTEN function as a stepwise gradation, which can be impaired not only by heterozygous mutations and homozygous losses, but also by other molecular mechanisms, such as transcriptional regression, epigenetic silencing, regulation by microRNAs, posttranslational modification, and aberrant localization.
    [Show full text]
  • Wnt-Independent and Wnt-Dependent Effects of APC Loss on the Chemotherapeutic Response
    International Journal of Molecular Sciences Review Wnt-Independent and Wnt-Dependent Effects of APC Loss on the Chemotherapeutic Response Casey D. Stefanski 1,2 and Jenifer R. Prosperi 1,2,3,* 1 Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46617, USA; [email protected] 2 Mike and Josie Harper Cancer Research Institute, South Bend, IN 46617, USA 3 Department of Biochemistry and Molecular Biology, Indiana University School of Medicine-South Bend, South Bend, IN 46617, USA * Correspondence: [email protected]; Tel.: +1-574-631-4002 Received: 30 September 2020; Accepted: 20 October 2020; Published: 22 October 2020 Abstract: Resistance to chemotherapy occurs through mechanisms within the epithelial tumor cells or through interactions with components of the tumor microenvironment (TME). Chemoresistance and the development of recurrent tumors are two of the leading factors of cancer-related deaths. The Adenomatous Polyposis Coli (APC) tumor suppressor is lost in many different cancers, including colorectal, breast, and prostate cancer, and its loss correlates with a decreased overall survival in cancer patients. While APC is commonly known for its role as a negative regulator of the WNT pathway, APC has numerous binding partners and functional roles. Through APC’s interactions with DNA repair proteins, DNA replication proteins, tubulin, and other components, recent evidence has shown that APC regulates the chemotherapy response in cancer cells. In this review article, we provide an overview of some of the cellular processes in which APC participates and how they impact chemoresistance through both epithelial- and TME-derived mechanisms. Keywords: adenomatous polyposis coli; chemoresistance; WNT signaling 1.
    [Show full text]
  • Teacher Background on P53 Tumor Suppressor Protein
    Cancer Lab p53 – Teacher Background on p53 Tumor Suppressor Protein Note: The Teacher Background Section is meant to provide information for the teacher about the topic and is tied very closely to the PowerPoint slide show. For greater understanding, the teacher may want to play the slide show as he/she reads the background section. For the students, the slide show can be used in its entirety or can be edited as necessary for a given class. What Is p53 and Where Is the Gene Located? While commonly known as p53, the official name of this gene is Tumor Protein p53 and its official symbol is TP53. TheTP53 gene codes for the TP53 (p53) protein which acts as a tumor suppressor and works in response to DNA damage to orchestrate the repair of damaged DNA. If the DNA cannot be repaired, the p53 protein prevents the cell from dividing and signals it to undergo apoptosis (programmed cell death). The name p53 is due to protein’s 53 kilo-Dalton molecular mass. The gene which codes for this protein is located on the short (p) arm of chromosome 17 at position 13.1 (17p13.1). The gene begins at base pair 7,571,719 and ends at base pair 7, 590,862 making it 19,143 base pairs long. (1, 2) What Does the p53 Gene Look Like When Translated Into Protein? The TP53 gene has 11 exons and a very large 10 kb intron between exons 1 and 2. In humans, exon 1 is non-coding and it has been shown that this region could form a stable stem-loop structure which binds tightly to normal p53 but not to mutant p53 proteins.
    [Show full text]
  • The NF2 Tumor Suppressor Merlin Interacts with Ras and Rasgap, Which May Modulate Ras Signaling
    Oncogene (2019) 38:6370–6381 https://doi.org/10.1038/s41388-019-0883-6 ARTICLE The NF2 tumor suppressor merlin interacts with Ras and RasGAP, which may modulate Ras signaling 1 1 2 1 1 1 Yan Cui ● Susann Groth ● Scott Troutman ● Annemarie Carlstedt ● Tobias Sperka ● Lars Björn Riecken ● 2 3 1 Joseph L. Kissil ● Hongchuan Jin ● Helen Morrison Received: 5 July 2018 / Revised: 31 March 2019 / Accepted: 1 May 2019 / Published online: 16 July 2019 © The Author(s) 2019. This article is published with open access Abstract Inactivation of the tumor suppressor NF2/merlin underlies neurofibromatosis type 2 (NF2) and some sporadic tumors. Previous studies have established that merlin mediates contact inhibition of proliferation; however, the exact mechanisms remain obscure and multiple pathways have been implicated. We have previously reported that merlin inhibits Ras and Rac activity during contact inhibition, but how merlin regulates Ras activity has remained elusive. Here we demonstrate that merlin can directly interact with both Ras and p120RasGAP (also named RasGAP). While merlin does not increase the catalytic activity of RasGAP, the interactions with Ras and RasGAP may fine-tune Ras signaling. In vivo, loss of RasGAP in 1234567890();,: 1234567890();,: Schwann cells, unlike the loss of merlin, failed to promote tumorigenic growth in an orthotopic model. Therefore, modulation of Ras signaling through RasGAP likely contributes to, but is not sufficient to account for, merlin’s tumor suppressor activity. Our study provides new insight into the mechanisms of merlin-dependent Ras regulation and may have additional implications for merlin-dependent regulation of other small GTPases. Introduction ependymomas, and astrocytomas [1].
    [Show full text]
  • Cancer Biology Introduction Proto-Oncogenes Tumor
    Introduction • Tissue homeostasis depends on the regulated cell division and self-elimination (programmed cell Cancer Biology death) of each of its constituent members except its stem cells • A tumor arises as a result of uncontrolled cell division and failure for self-elimination Chapter 18 • Alterations in three groups of genes are responsible Eric J. Hall., Amato Giaccia, for the deregulated control mechanisms that are the hallmarks of cancer cells: proto-oncogenes, tumor- Radiobiology for the Radiologist supressor genes, and DNA stability genes Proto-oncogenes Tumor-suppressor genes • Proto-oncogenes are components of signaling • Tumor-suppressor genes are also components of networks that act as positive growth the same signaling networks as proto-oncogenes, except that they act as negative growth regulators regulators in response to mitogens, cytokines, • They modulate proliferation and survival by and cell-to-cell contact antagonizing the biochemical functions of proto- • A gain-of-function mutation in only one copy oncogenes or responding to unchecked growth signals of a protooncogene results in a dominantly • In contrast to oncogenes, inactivation of both acting oncogene that often fails to respond to copies of tumor-suppressor genes is required for extracellular signals loss of function in most cases DNA stability genes Mechanisms of carcinogenesis • DNA stability genes form a class of genes • A single genetic alteration that leads to the involved in both monitoring and activation of an oncogene or loss of a tumor maintaining
    [Show full text]
  • Expression of a Down-Regulated Target, Ssecks, Reverses V-Jun-Induced Transformation of 10T1/2 Murine ®Broblasts
    Oncogene (2001) 20, 141 ± 146 ã 2001 Nature Publishing Group All rights reserved 0950 ± 9232/01 $15.00 www.nature.com/onc ORIGINAL PAPERS Expression of a down-regulated target, SSeCKS, reverses v-Jun-induced transformation of 10T1/2 murine ®broblasts Steven B Cohen1, Anke Waha2, Iwin H Gelman3 and Peter K Vogt*,2 1Gen-Probe Incorporated, 10210 Genetic Center Drive, San Diego, California CA 92121, USA; 2Department of Molecular and Experimental Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California CA 92037, USA; 3Department of Microbiology, Mount Sinai School of Medicine, New York, NY 10029-6574, USA Line 10T1/2 mouse ®broblast overexpressing the v-Jun its cellular counterpart by a 27-amino acid deletion and oncoprotein were morphologically altered, grew into by two amino acid substitutions (Nishimura and Vogt, multilayered foci in culture and formed colonies when 1988). These mutations synergize to make Jun suspended in agar. The growth rate of the v-Jun- independent of cellular regulation and to turn it into transformed 10T1/2 cells was not changed signi®cantly a strong growth promoter (Abate et al., 1990; Boyle et from that of the untransformed parental cells, but the al., 1991; Chida and Vogt, 1992; Hibi et al., 1993; saturation density of the transformed cultures exceeded Morgan et al., 1993; 1994). that of normal controls by a factor of 2. mRNA v-Jun induces oncogenic transformation by aberrant extracted from v-Jun-transformed 10T1/2 cells was regulation of speci®c target genes. The dierential analysed for dierential gene expression with DNA expression of these targets determines the neoplastic micro-array technology.
    [Show full text]
  • The Functional Loss of the Retinoblastoma Tumour Suppressor
    Available online http://breast-cancer-research.com/content/10/5/R75 ResearchVol 10 No 5 article Open Access The functional loss of the retinoblastoma tumour suppressor is a common event in basal-like and luminal B breast carcinomas Jason I Herschkowitz1,2,4, Xiaping He1,2, Cheng Fan1 and Charles M Perou1,2,3 1Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA 2Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA 3Department of Pathology & Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA 4Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, DeBakey M635, Houston, TX 77030, USA Corresponding author: Charles M Perou, [email protected] Received: 19 Jun 2008 Revisions requested: 31 Jul 2008 Revisions received: 22 Aug 2008 Accepted: 9 Sep 2008 Published: 9 Sep 2008 Breast Cancer Research 2008, 10:R75 (doi:10.1186/bcr2142) This article is online at: http://breast-cancer-research.com/content/10/5/R75 © 2008 Herschkowitz et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Introduction Breast cancers can be classified using whole Results RB1 loss of heterozygosity was observed at an overall genome expression into distinct subtypes that show differences frequency of 39%, with a high frequency in basal-like (72%) and in prognosis. One of these groups, the basal-like subtype, is luminal B (62%) tumours.
    [Show full text]
  • Utimmunohistochemical Detection of the Alternate Ink4a-Encoded
    utImmunohistochemical Detection of the Alternate INK4a-Encoded Tumor Suppressor Protein p14ARF in Archival Human Cancers and Cell Lines Using Commercial Antibodies: Correlation with p16INK4a Expression Joseph Geradts, M.D., Robb E. Wilentz, M.D., Helen Roberts, B.Sc. Nuffield Department of Clinical Laboratory Sciences (JG, HR), University of Oxford, John Radcliffe Hospital, Oxford, UK; and Department of Pathology (REW), The Johns Hopkins University School of Medicine, Baltimore, Maryland KEY WORDS: Antibodies, Immunohistochemistry, The INK4a locus encodes two structurally unrelated INK4a, p14ARF, p16INK4a. tumor suppressor proteins, p16INK4a and p14ARF. Mod Pathol 2001;14(11):1162–1168 Although the former is one of the most common targets for inactivation in human neoplasia, the fre- The INK4a gene on chromosome 9p21 is one of the quency of p14ARF abrogation is not established. We most common targets for inactivation in human have developed an immunohistochemical assay neoplasia. The gene is unusual in that it encodes that allows the evaluation of p14ARF expression in two structurally unrelated proteins, p16INK4a and formalin-fixed, paraffin-embedded tissues, using p14ARF, the human homologue of murine p19ARF. commercially available antibodies. p14ARF positive Two different first exons are spliced in different cells showed nuclear/nucleolar staining, which was reading frames to common exon 2 (1). p16INK4a acts absent in all cell lines and tumors with homozygous as a retinoblastoma protein (pRB) agonist by inhib- deletions of the INK4a gene. The assay was applied iting the phosphorylation of pRB by activated to 34 paraffin-embedded cell buttons, 30 non-small cyclin-dependent kinases 4 and 6 (2). The principal INK4a cell lung cancers and 28 pancreatic carcinomas, and methods of p16 inactivation are homozygous the staining results were correlated with p16INK4a deletion of the gene, promoter methylation of exon ARF 1␣, and intragenic mutation (3).
    [Show full text]
  • Cancer Genes & Cancer Genetics
    Cancer Genes & Cancer Genetics NO office hours this Friday (5-1). Please set up an appointment if you any questions. [email protected] READING: pp. 202-220 Somatic Cells/Germ line mutations This nothing to do with + bugs Mutations passed on to progeny, all tissues, Mendelian Mutations usually little effect, cell death GERM LINE for damaged female: eggs cell; however, all cancers arise from somatic cell (precursors) mutation, one cell confined male: sperm to one tissue SOMATIC CELLS embryo proper all tissues GO STOP Cell Proliferation and Death STOP GO + Uncontrolled cell Cell division comes from suicide accumulation of (programmed cell death) genetic defects that lead to too much "go" signal, too little "stop" signal, and loss of cell suicide proliferation and programmed cell death tightly regulated to ensure the integrity of organs and tissues Checkpoint The Cell Cycle Mitosis (M-phase) STOP GO M G2 G1 S G1 G2 S STOP Checkpoint tumor suppressors (-) STOP proto-oncogenes (+) GO Checkpoints ensure the cell cycle proceeds without errors Cancer Genes Accumulation of multiple mutations Potential cancer genes - about 100 (0.3% of total) genes Inappropriate signals about need for cell division (hormonal signaling pathways: growth factors) GO Malfunctions in (CDK-cyclin) complexes controlling cell cycle transitions STOP Checkpoint breakdowns leading to DNA instability Loss of programmed cell death (cell suicide) Invasion/Metastasis Part 1: Tumor Suppressor Genes Loss-of-Function (LOF) Function no checkpoint stop; no DNA repair; STOP signal
    [Show full text]