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Thakkar MK, Lee J, Meyer S, Chang VY. RecQ Helicase Somatic Alterations in Cancer. Front Mol Biosci 2022; 9:887758. [PMID: 35782872 PMCID: PMC9240438 DOI: 10.3389/fmolb.2022.887758] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 05/23/2022] [Indexed: 11/13/2022] Open
Abstract
Named the “caretakers” of the genome, RecQ helicases function in several pathways to maintain genomic stability and repair DNA. This highly conserved family of enzymes consist of five different proteins in humans: RECQL1, BLM, WRN, RECQL4, and RECQL5. Biallelic germline mutations in BLM, WRN, and RECQL4 have been linked to rare cancer-predisposing syndromes. Emerging research has also implicated somatic alterations in RecQ helicases in a variety of cancers, including hematological malignancies, breast cancer, osteosarcoma, amongst others. These alterations in RecQ helicases, particularly overexpression, may lead to increased resistance of cancer cells to conventional chemotherapy. Downregulation of these proteins may allow for increased sensitivity to chemotherapy, and, therefore, may be important therapeutic targets. Here we provide a comprehensive review of our current understanding of the role of RecQ DNA helicases in cancer and discuss the potential therapeutic opportunities in targeting these helicases.
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Affiliation(s)
- Megha K. Thakkar
- Department of Pediatrics, Division of Pediatric Hematology-Oncology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Jamie Lee
- Department of Pediatrics, Division of Pediatric Hematology-Oncology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Stefan Meyer
- Division of Cancer Studies, University of Manchester, Manchester, United Kingdom
- Department of Pediatric Hematology Oncology, Royal Manchester Children’s Hospital and Christie NHS Foundation Trust, Manchester, United Kingdom
| | - Vivian Y. Chang
- Department of Pediatrics, Division of Pediatric Hematology-Oncology, University of California, Los Angeles, Los Angeles, CA, United States
- Childrens Discovery and Innovation Institute, UCLA, Los Angeles, CA, United States
- Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, CA, United States
- *Correspondence: Vivian Y. Chang,
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Wang P, Wang Y, Langley SA, Zhou YX, Jen KY, Sun Q, Brislawn C, Rojas CM, Wahl KL, Wang T, Fan X, Jansson JK, Celniker SE, Zou X, Threadgill DW, Snijders AM, Mao JH. Diverse tumour susceptibility in Collaborative Cross mice: identification of a new mouse model for human gastric tumourigenesis. Gut 2019; 68:1942-1952. [PMID: 30842212 PMCID: PMC6839736 DOI: 10.1136/gutjnl-2018-316691] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 02/11/2019] [Accepted: 02/12/2019] [Indexed: 12/20/2022]
Abstract
OBJECTIVE The Collaborative Cross (CC) is a mouse population model with diverse and reproducible genetic backgrounds used to identify novel disease models and genes that contribute to human disease. Since spontaneous tumour susceptibility in CC mice remains unexplored, we assessed tumour incidence and spectrum. DESIGN We monitored 293 mice from 18 CC strains for tumour development. Genetic association analysis and RNA sequencing were used to identify susceptibility loci and candidate genes. We analysed genomes of patients with gastric cancer to evaluate the relevance of genes identified in the CC mouse model and measured the expression levels of ISG15 by immunohistochemical staining using a gastric adenocarcinoma tissue microarray. Association of gene expression with overall survival (OS) was assessed by Kaplan-Meier analysis. RESULTS CC mice displayed a wide range in the incidence and types of spontaneous tumours. More than 40% of CC036 mice developed gastric tumours within 1 year. Genetic association analysis identified Nfκb1 as a candidate susceptibility gene, while RNA sequencing analysis of non-tumour gastric tissues from CC036 mice showed significantly higher expression of inflammatory response genes. In human gastric cancers, the majority of human orthologues of the 166 mouse genes were preferentially altered by amplification or deletion and were significantly associated with OS. Higher expression of the CC036 inflammatory response gene signature is associated with poor OS. Finally, ISG15 protein is elevated in gastric adenocarcinomas and correlated with shortened patient OS. CONCLUSIONS CC strains exhibit tremendous variation in tumour susceptibility, and we present CC036 as a spontaneous laboratory mouse model for studying human gastric tumourigenesis.
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Affiliation(s)
- Pin Wang
- Department of Gastroenterology, Nanjing Drum Tower Hospital, Affiliated Hospital of Nanjing University Medical School, Nanjing, Jiangsu, China,Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Yunshan Wang
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA,Clinical Laboratory, Second Hospital of Shandong University, Jinan, China
| | - Sasha A Langley
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Yan-Xia Zhou
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA,College of Marine Science, Shandong University, Weihai, China
| | - Kuang-Yu Jen
- Department of Pathology, University of California Davis Medical Center, Sacramento, California, USA
| | - Qi Sun
- Department of Pathology, Nanjing Drum Tower Hospital, Affiliated Hospital of Nanjing University Medical School, Nanjing, China
| | - Colin Brislawn
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Carolina M Rojas
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, USA,Department of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas, USA
| | - Kimberly L Wahl
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, USA,Department of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas, USA
| | - Ting Wang
- Department of Pathology, Nanjing Drum Tower Hospital, Affiliated Hospital of Nanjing University Medical School, Nanjing, China
| | - Xiangshan Fan
- Department of Pathology, Nanjing Drum Tower Hospital, Affiliated Hospital of Nanjing University Medical School, Nanjing, China
| | - Janet K Jansson
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Susan E Celniker
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Xiaoping Zou
- Department of Gastroenterology, Nanjing Drum Tower Hospital, Affiliated Hospital of Nanjing University Medical School, Nanjing, Jiangsu, China
| | - David W Threadgill
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, USA,Department of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas, USA
| | - Antoine M Snijders
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Jian-Hua Mao
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
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3
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Prediction of response to anti-cancer drugs becomes robust via network integration of molecular data. Sci Rep 2019; 9:2379. [PMID: 30787419 PMCID: PMC6382934 DOI: 10.1038/s41598-019-39019-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 01/11/2019] [Indexed: 12/20/2022] Open
Abstract
Despite the widening range of high-throughput platforms and exponential growth of generated data volume, the validation of biomarkers discovered from large-scale data remains a challenging field. In order to tackle cancer heterogeneity and comply with the data dimensionality, a number of network and pathway approaches were invented but rarely systematically applied to this task. We propose a new method, called NEAmarker, for finding sensitive and robust biomarkers at the pathway level. scores from network enrichment analysis transform the original space of altered genes into a lower-dimensional space of pathways. These dimensions are then correlated with phenotype variables. The method was first tested using in vitro data from three anti-cancer drug screens and then on clinical data of The Cancer Genome Atlas. It proved superior to the single-gene and alternative enrichment analyses in terms of (1) universal applicability to different data types with a possibility of cross-platform integration, (2) consistency of the discovered correlates between independent drug screens, and (3) ability to explain differential survival of treated patients. Our new screen of anti-cancer compounds validated the performance of multivariate models of drug sensitivity. The previously proposed methods of enrichment analysis could achieve comparable levels of performance in certain tests. However, only our method could discover predictors of both in vitro response and patient survival given administration of the same drug.
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4
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Snijders AM, Lee SY, Hang B, Hao W, Bissell MJ, Mao JH. FAM83 family oncogenes are broadly involved in human cancers: an integrative multi-omics approach. Mol Oncol 2017; 11:167-179. [PMID: 28078827 PMCID: PMC5527452 DOI: 10.1002/1878-0261.12016] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 09/16/2016] [Accepted: 10/21/2016] [Indexed: 01/15/2023] Open
Abstract
The development of novel targeted therapies for cancer treatment requires identification of reliable targets. FAM83 (‘family with sequence similarity 83’) family members A, B, and D were shown recently to have oncogenic potential. However, the overall oncogenic abilities of FAM83 family genes remain largely unknown. Here, we used a systematic and integrative genomics approach to investigate oncogenic properties of the entire FAM83 family members. We assessed transcriptional expression patterns of eight FAM83 family genes (FAM83A‐H) across tumor types, the relationship between their expression and changes in DNA copy number, and the association with patient survival. By comparing the gene expression levels of FAM83 family members in cancers from 17 different tumor types with those in their corresponding normal tissues, we identified consistent upregulation of FAM83D and FAM83H across the majority of tumor types, which is largely driven by increased DNA copy number. Importantly, we found also that a higher expression level of a signature of FAM83 family members was associated with poor prognosis in a number of human cancers. In breast cancer, we found that alterations in FAM83 family genes correlated significantly with TP53 mutation, whereas significant, but inverse correlation was observed with PIK3CA and CDH1 (E‐cadherin) mutations. We also identified that expression levels of 55 proteins were significantly associated with alterations in FAM83 family genes including a decrease in GATA3, ESR1, and PGR proteins in tumors with alterations in FAM83. Our results provide strong evidence for a critical role of FAM83 family genes in tumor development, with possible relevance for therapeutic target development.
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Affiliation(s)
- Antoine M Snijders
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, CA, USA
| | - Sun-Young Lee
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, CA, USA
| | - Bo Hang
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, CA, USA
| | - Wenshan Hao
- Nanjing Biotech and Pharmaceutical Valley Development Center, China
| | - Mina J Bissell
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, CA, USA
| | - Jian-Hua Mao
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, CA, USA
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Adamia S, Kriangkum J, Belch AR, Pilarski LM. Aberrant posttranscriptional processing of hyaluronan synthase 1 in malignant transformation and tumor progression. Adv Cancer Res 2015; 123:67-94. [PMID: 25081526 DOI: 10.1016/b978-0-12-800092-2.00003-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
It is becoming increasingly apparent that splicing defects play a key role in cancer, and that alterations in genomic splicing elements promote aberrant splicing. Alternative splicing increases the diversity of the human transcriptome and increases the numbers of functional gene products. However, dysregulation that leads to aberrant pre-mRNA splicing can contribute to cancer. Hyaluronan (HA), known to be an important component of cancer progression, is synthesized by hyaluronan synthases (HASs). In cancer cells, hyaluronan synthase 1 (HAS1) pre-mRNA is abnormally spliced to generate a family of aberrant splice variants (HAS1Vs) that synthesize extracellular and intracellular HA. HAS1Vs are clinically relevant, being found almost exclusively in malignant cells. Expression of aberrant HAS1Vs predicts poor survival in multiple myeloma. In this review, we summarize the unusual properties of HAS1Vs and their relationship to cancer. HAS1Vs form heterogeneous multimers with normally spliced HAS1 as well as with each other and with HAS3. Aberrant variants of HAS1 synthesize HA. Extracellular HA synthesized by HAS1Vs is likely to promote malignant spread. We speculate that synthesis of intracellular HA plays a fundamental and early role in oncogenesis by promoting genetic instability and the emergence of viable cancer variants that lead to aggressive disease.
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Affiliation(s)
- Sophia Adamia
- Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA.
| | - Jitra Kriangkum
- Department of Oncology, University of Alberta and Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Andrew R Belch
- Department of Oncology, University of Alberta and Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Linda M Pilarski
- Department of Oncology, University of Alberta and Cross Cancer Institute, Edmonton, Alberta, Canada
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Yan KH, Lee LM, Hsieh MC, Yan MD, Yao CJ, Chang PY, Chen TL, Chang HY, Cheng AL, Lai GM, Chuang SE. Aspirin antagonizes the cytotoxic effect of methotrexate in lung cancer cells. Oncol Rep 2013; 30:1497-505. [PMID: 23799623 DOI: 10.3892/or.2013.2561] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 05/09/2013] [Indexed: 11/06/2022] Open
Abstract
Methotrexate (MTX) has been widely used for the treatment of cancer and rheumatoid arthritis (RA). Aspirin (ASA) is a non-selective cyclooxygenase (COX) inhibitor that contributes to the treatment of inflammatory conditions such as RA. It has been observed that the antitumor effect of ASA can be attributed to inhibition of cell cycle progression, induction of apoptosis and inhibition of angiogenesis. In the present study, we revealed that the treatment with a combination of MTX and ASA resulted in antagonism of the cytotoxic effect as demonstrated by SRB and colony formation assays. ASA alleviated the MTX-mediated S phase accumulation and recovered the G1 phase. MTX-mediated accumulation of the S phase marker cyclin A was also alleviated by ASA. Notably, FAS protein levels were upregulated by MTX in A549 cells. The antagonism of MTX efficacy caused by ASA was accompanied by altered expression of caspase-3, Bcl-2 and FAS but not dihydrofolate reductase (DHFR). This suggests that the alteration of caspase-3, Bcl-2 and FAS was involved in the antagonism between ASA and MTX. Exogenously added folic acid reversed the MTX-mediated DHFR inhibition following either MTX or MTX + ASA treatments. Most importantly, we demonstrated for the first time that the commonly used non-steroidal anti-inflammatory drug for headache ASA and possibly other COX-1/2 inhibitors can produce a strong antagonistic effect on the growth inhibition of lung cancer cells when administered in combination with MTX. The clinical implication of our finding is obvious, i.e., the clinical efficacy of MTX therapy can be compromised by ASA and their concomitant use should be avoided.
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Affiliation(s)
- Kun-Huang Yan
- Department of Urology, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan, R.O.C
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Chung TH, Mulligan G, Fonseca R, Chng WJ. A novel measure of chromosome instability can account for prognostic difference in multiple myeloma. PLoS One 2013; 8:e66361. [PMID: 23840451 PMCID: PMC3688789 DOI: 10.1371/journal.pone.0066361] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 05/04/2013] [Indexed: 11/25/2022] Open
Abstract
Multiple myeloma (MM) is characterized by complex genetic abnormalities whose complexity signifies varying degree of chromosomal instability (CIN). In this study, we introduced a novel CIN measure, chromosome instability genome event count (CINGEC), which considered both copy number aberrations and interstitial breakpoints from high-resolution genome-wide assays. When assessed in two aCGH MM datasets, higher CINGEC was associated with poor survival. We then derived a CINGEC-associated gene expression profile (GEP) signature, CINGECS, using a dataset that has both aCGH and GEP. Genes in CINGECS were mainly involved in DNA damage responses besides in aneuploidy and other generic oncogenic processes contrary to other CIN associated GEP signatures. Finally, we confirmed its survival association in three GEP datasets that encompassed newly diagnosed patients treated with transplant-based protocol with or without novel agents for induction as well as relapsed patients treated with bortezomib. Furthermore, CINGECS was independent of many GEP-based prognostic signatures. In conclusion, our novel CIN measure has definite biological and clinical significance in myeloma.
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Affiliation(s)
- Tae-Hoon Chung
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
| | - George Mulligan
- Millenium: The Takeda Oncology, Cambridge, Massachusetts, United States of America
| | - Rafael Fonseca
- Mayo Clinic Comprehensive Cancer Center, Scottsdale, Arizona, United States of America
| | - Wee Joo Chng
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Haematology-Oncology, National University Cancer Institute of Singapore, National University Health System, Singapore, Singapore
- * E-mail:
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Martin SA, McCarthy A, Barber LJ, Burgess DJ, Parry S, Lord CJ, Ashworth A. Methotrexate induces oxidative DNA damage and is selectively lethal to tumour cells with defects in the DNA mismatch repair gene MSH2. EMBO Mol Med 2010; 1:323-37. [PMID: 20049736 PMCID: PMC3378145 DOI: 10.1002/emmm.200900040] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Mutations in the MSH2 gene predispose to a number of tumourigenic conditions, including hereditary non-polyposis colon cancer (HNPCC). MSH2 encodes a protein in the mismatch repair (MMR) pathway which is involved in the removal of mispairs originating during replication or from damaged DNA. To identify new therapeutic strategies for the treatment of cancer arising from MMR deficiency, we screened a small molecule library encompassing previously utilized drugs and drug-like molecules to identify agents selectively lethal to cells lacking functional MSH2. This approach identified the drug methotrexate as being highly selective for cells with MSH2 deficiency. Methotrexate treatment caused the accumulation of potentially lethal 8-hydroxy-2'-deoxyguanosine (8-OHdG) oxidative DNA lesions in both MSH2 deficient and proficient cells. In MSH2 proficient cells, these lesions were rapidly cleared, while in MSH2 deficient cells 8-OHdG lesions persisted, potentially explaining the selectivity of methotrexate. Short interfering (si)RNA mediated silencing of the target of methotrexate, dihydrofolate reductase (DHFR), was also selective for MSH2 deficiency and also caused an accumulation of 8-OHdG. This suggested that the ability of methotrexate to modulate folate synthesis via inhibition of DHFR, may explain MSH2 selectivity. Consistent with this hypothesis, addition of folic acid to culture media substantially rescued the lethal phenotype caused by methotrexate. While methotrexate has been used for many years as a cancer therapy, our observations suggest that this drug may have particular utility for the treatment of a subset of patients with tumours characterized by MSH2 mutations.
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Affiliation(s)
- Sarah A Martin
- Cancer Research UK Gene Function and Regulation Group, The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, UK
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Davari P, Hebert JL, Albertson DG, Huey B, Roy R, Mancianti ML, Horvai AE, McDaniel LD, Schultz RA, Epstein EH. Loss of Blm enhances basal cell carcinoma and rhabdomyosarcoma tumorigenesis in Ptch1+/- mice. Carcinogenesis 2009; 31:968-73. [PMID: 19995795 DOI: 10.1093/carcin/bgp309] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Basal cell carcinomas (BCCs) have relative genomic stability and relatively benign clinical behavior but whether these two are related causally is unknown. To investigate the effects of introducing genomic instability into murine BCCs, we have compared ionizing radiation-induced tumorigenesis in Ptch1(+/-) mice versus that in Ptch1(+/-) mice carrying mutant Blm alleles. We found that BCCs in Ptch1(+/-) Blm(tm3Brd/tm3Brd) mice had a trend toward greater genomic instability as measured by array comprehensive genomic hybridization and that these mice developed significantly more microscopic BCCs than did Ptch1(+/-) Blm(+/tm3Brd) or Ptch1(+/-) Blm(+/+) mice. The mutant Blm alleles also markedly enhanced the formation of rhabdomyosarcomas (RMSs), another cancer to which Ptch1(+/)(-) mice and PTCH1(+/)(-) (basal cell nevus syndrome) patients are susceptible. Highly recurrent but different copy number changes were associated with the two tumor types and included losses of chromosomes 4 and 10 in all BCCs and gain of chromosome 10 in 80% of RMSs. Loss of chromosome 11 and 13, including the Trp53 and Ptch1 loci, respectively, occurred frequently in BCCs, suggesting tissue-specific selection for genes or pathways that collaborate with Ptch deficiency in tumorigenesis. Despite the quantitative differences, there was no dramatic qualititative difference in the BCC or RMS tumors associated with the mutant Blm genotype.
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Affiliation(s)
- Parastoo Davari
- Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr Way, Oakland, CA 94609, USA
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Hattinger CM, Stoico G, Michelacci F, Pasello M, Scionti I, Remondini D, Castellani GC, Fanelli M, Scotlandi K, Picci P, Serra M. Mechanisms of gene amplification and evidence of coamplification in drug-resistant human osteosarcoma cell lines. Genes Chromosomes Cancer 2009; 48:289-309. [PMID: 19105235 DOI: 10.1002/gcc.20640] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Gene amplification and copy number changes play a pivotal role in malignant transformation and progression of human tumor cells by mediating the activation of genes and oncogenes, which are involved in many different cellular processes including development of drug resistance. Since doxorubicin (DX) and methotrexate (MTX) are the two most important drugs for high-grade osteosarcoma (OS) treatment, the aim of this study was to identify genes gained or amplified in six DX- and eight MTX-resistant variants of the human OS cell lines U-2OS and Saos-2, and to get insights into the mechanisms underlying the amplification processes. Comparative genomic hybridization techniques identified amplification of MDR1 in all six DX-resistant and of DHFR in three MTX-resistant U-2OS variants. In addition, progressive gain of MLL was detected in the four U-2OS variants with higher resistance levels either to DX or MTX, whereas gain of MYC was found in all Saos-2 MTX-resistant variants and the U-2OS variant with the highest resistance level to DX. Fluorescent in situ hybridization revealed that MDR1 was amplified in U-2OS and Saos-2/DX-resistant variants manifested as homogeneously staining regions and double minutes, respectively. In U-2OS/MTX-resistant variants, DHFR was amplified in homogeneously staining regions, and was coamplified with MLL in relation to the increase of resistance to MTX. Gene amplification was associated with gene overexpression, whereas gene gain resulted in up-regulated gene expression. These results indicate that resistance to DX and MTX in human OS cell lines is a multigenic process involving gene copy number and expression changes.
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Affiliation(s)
- Claudia M Hattinger
- Laboratorio di Ricerca Oncologica, Istituti Ortopedici Rizzoli, Bologna, Italy
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Morales C, García MJ, Ribas M, Miró R, Muñoz M, Caldas C, Peinado MA. Dihydrofolate reductase amplification and sensitization to methotrexate of methotrexate-resistant colon cancer cells. Mol Cancer Ther 2009; 8:424-32. [DOI: 10.1158/1535-7163.mct-08-0759] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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12
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Stromal control of oncogenic traits expressed in response to the overexpression of GLI2, a pleiotropic oncogene. Oncogene 2008; 28:625-37. [PMID: 19015636 PMCID: PMC2643346 DOI: 10.1038/onc.2008.421] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hedgehog signaling is often activated in tumors, yet it remains unclear how GLI2, a transcription factor activated by this pathway, acts as an oncogene. We show that GLI2 is a pleiotropic oncogene. Overexpression induces genomic instability and blocks differentiation, likely mediated in part by enhanced expression of the stem cell gene SOX2. GLI2 also induces TGFβ dependent transdifferentiation of foreskin and tongue, but not gingival fibroblasts into myofibroblasts, creating an environment permissive for invasion by keratinocytes, which are in various stages of differentiation having down regulated GLI2. Thus, up-regulated GLI2 expression is sufficient to induce a number of the acquired characteristics of tumor cells; however the stroma, in a tissue specific manner, determines whether certain GLI2 oncogenic traits are expressed.
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