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Ravella L, Lopez J, Descotes F, Giai J, Lapras V, Denier ML, Borson-Chazot F, Lifante JC, Decaussin-Petrucci M. Preoperative Role of RAS or BRAF K601E in the Guidance of Surgery for Indeterminate Thyroid Nodules. World J Surg 2020; 44:2264-71. [PMID: 32227276 DOI: 10.1007/s00268-020-05487-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND RAS and K601E BRAF mutations are not a reliable indicator of malignancy in fine-needle aspirations (FNA) of thyroid indeterminate cytologic nodules. We aimed to evaluate the histologic characteristics, the risk of malignancy associated with such mutations in FNA and their potential interest for preoperative clinical management of nodules. METHODS We evaluated 69 indeterminate thyroid nodules with RAS or K601E BRAF mutations with available histopathologic follow-up. All FNA specimens were indeterminate according to the thyroid Bethesda system. Diagnosis of malignant, benign or indolent neoplasms was classified according to 2017 WHO classification. Carcinoma, NIFTP (noninvasive follicular thyroid neoplasm with papillary-like features) and WDTUMP (well-differentiated tumor of uncertain malignant potential) were considered "surgical," as they require surgical excision. Adenoma was considered "non-surgical." The risk of malignancy and the risk of "surgical disease" were evaluated. RESULTS Pathologic evaluation of the 69 mutated nodules demonstrated benign, indolent and malignant histology in 17 cases (25%), 21 cases (30%) and 31 cases (45%), respectively. The risk of malignancy was 45%, and the risk of surgical disease was 75%. The majority of carcinomas were a follicular variant of papillary thyroid carcinoma. On follow-up, there have been no recurrences to date. CONCLUSION Preoperative RAS or BRAF K601E mutations detection in cytologic indeterminate thyroid nodules carries a high risk of surgical disease and may benefit from surgical management. Most surgical lesions harboring those mutations are low-risk tumors, which may be in favor of an initial lobectomy.
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2
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Shrestha RT, Kizilgul M, Shahi M, Amin K, Evasovich MR, Burmeister LA. Impact of molecular testing on thyroid nodule neoplastic diagnosis, stratified by 4-cm size, in a surgical series. Sci Rep 2019; 9:17861. [PMID: 31780751 PMCID: PMC6883052 DOI: 10.1038/s41598-019-52581-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 10/17/2019] [Indexed: 11/09/2022] Open
Abstract
Whether molecular testing adds diagnostic value to the evaluation of thyroid nodules 4-cm or larger is unknown. The impact of molecular testing on cytopathologic-histopathologic diagnosis of neoplasm (adenoma or malignant), stratified by nodule size
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Affiliation(s)
| | - Muhammed Kizilgul
- Department of Medicine, University of Minnesota, Minneapolis, USA
- Department of Endocrinology and Metabolism, UHS Diskapi Training and Research Hospital, Ankara, Turkey
| | - Maryam Shahi
- Department of Pathology, University of Minnesota, Minneapolis, USA
| | - Khalid Amin
- Department of Pathology, University of Minnesota, Minneapolis, USA
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3
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Kim HK, Lee I, Lee J, Chang HS, Soh EY, Park IS, Kim JH, Rho YS, Lee DJ. BRAF wild papillary thyroid carcinoma has two distinct mRNA expression patterns with different clinical behaviors. Head Neck 2018; 40:1707-1718. [PMID: 29573027 DOI: 10.1002/hed.25151] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 11/06/2017] [Accepted: 02/05/2018] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Using a large set of genomic data from The Cancer Genome Atlas (TCGA), we classified BRAFwild papillary thyroid carcinomas (PTCs) into 2 subtypes with distinct molecular patterns and different clinical behaviors. We also suggested gene signatures (RAS-score) to predict molecular subtypes and clinical behaviors of BRAFwild PTC. METHOD Integrated genomic analysis was done using all genomic data of PTC in TCGA data portal (https://tcga-data.nci.nih.gov) and cancer browser (https://genome-cancer.ucsc.edu). Using Gene Ontology and a logistic regression test, we selected gene signatures (RAS-score) and applied this prediction model to the validation cohort (GSE60542). RESULT When we performed multiplatform genomic analysis, BRAFwild PTCs were divided into 2 molecular subtypes. Each subtype showed distinct molecular patterns and clinical behaviors. Gene signatures successfully predicted molecular subtype in another validation cohort. CONCLUSION We found that BRAFwild PTCs were divided into 2 molecular subtypes and each subtype showed distinct molecular patterns, different activated pathways, and different clinical behaviors.
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Affiliation(s)
- Hyeung Kyoo Kim
- Department of Surgery, Ajou University School of Medicine, Suwon, South Korea.,Department of Surgery, Graduate School, Yonsei University College of Medicine, Seoul, South Korea
| | - Inhwa Lee
- Department of Surgery, Ajou University School of Medicine, Suwon, South Korea
| | - Jeonghun Lee
- Department of Surgery, Ajou University School of Medicine, Suwon, South Korea
| | - Hang-Seok Chang
- Department of Surgery, Graduate School, Yonsei University College of Medicine, Seoul, South Korea
| | - Euy Young Soh
- Department of Surgery, Ajou University School of Medicine, Suwon, South Korea
| | - Il Seok Park
- Department of Otolaryngology - Head and Neck Surgery, Kangnam Sacret Heart Hospital, Hallym University College of Medicine, Seoul, South Korea
| | - Jin Hwan Kim
- Department of Otolaryngology - Head and Neck Surgery, Kangnam Sacret Heart Hospital, Hallym University College of Medicine, Seoul, South Korea
| | - Young Soo Rho
- Department of Otolaryngology - Head and Neck Surgery, Kangnam Sacret Heart Hospital, Hallym University College of Medicine, Seoul, South Korea
| | - Dong Jin Lee
- Department of Otolaryngology - Head and Neck Surgery, Kangnam Sacret Heart Hospital, Hallym University College of Medicine, Seoul, South Korea
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4
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Sipos JA, Blevins TC, Shea HC, Duick DS, Lakhian SK, Michael BE, Thomas MJ, Sosa JA. LONG-TERM NONOPERATIVE RATE OF THYROID NODULES WITH BENIGN RESULTS ON THE AFIRMA GENE EXPRESSION CLASSIFIER. Endocr Pract 2016; 22:666-72. [PMID: 26789352 DOI: 10.4158/ep151006.or] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
OBJECTIVE The primary objective was to assess the operative rate in patients with a benign result from the Afirma gene expression classifier (GEC) during long-term follow-up at nonacademic medical facilities. The secondary endpoint of this study was the treating physician's opinion regarding the safety of GEC use compared to the hypothetical situation of providing thyroid nodule management without the GEC. METHODS This was a retrospective study of nonacademic medical practices utilizing the GEC. Those clinicians utilizing the GEC testing who had three or more 'benign' results during the data collection period (September 2010 through June 2014) were invited to participate. Operative status and patient demographics were documented for patients with GEC testing at least 36 months (± 3 months) prior to the date of data collection. A survey also was administered to the treating physicians to assess their perceived safety of using the GEC in patient care. RESULTS During 36 months (± 3 months) of follow-up, 17 of 98 patients (17.3%) with a 'benign' GEC result underwent surgery. Within the first 2 years after a 'benign' GEC, 88% of surgeries were performed. Regarding safety of the GEC, the treating physicians reported that patient safety was improved by using the GEC compared to not using the GEC in 78 of 91 cases (86%). CONCLUSION It appears that a 'benign' result on the GEC is associated with a reduction in the rate of thyroid surgeries compared to published data when patients are followed for 36 months after testing. A nonoperative approach to follow-up was felt to be a safe alternative to diagnostic surgery by the majority of responsible physicians in the study. ABBREVIATIONS AUS = atypia of undetermined significance FLUS = follicular lesion of undetermined significance FN = follicular neoplasm FNA = fine-needle aspiration GEC = gene expression classifier.
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5
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Affiliation(s)
- Tae Sook Hwang
- Department of Pathology, Konkuk University School of Medicine, Seoul, Korea
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6
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Le Mercier M, D'Haene N, De Nève N, Blanchard O, Degand C, Rorive S, Salmon I. Next-generation sequencing improves the diagnosis of thyroid FNA specimens with indeterminate cytology. Histopathology 2014; 66:215-24. [PMID: 24834793 DOI: 10.1111/his.12461] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 05/14/2014] [Indexed: 01/21/2023]
Abstract
AIMS The assessment of thyroid nodules is a common clinical challenge. Fine-needle aspiration (FNA) is the standard pre-operative tool for thyroid nodule diagnosis. However, up to 30% of the samples are classified as indeterminate. This often leads to unnecessary surgery. In this study, we evaluated the added value of next-generation sequencing (NGS) for helping in the diagnosis of FNA samples. METHODS AND RESULTS We analysed retrospectively 34 indeterminate FNA samples for which surgical resection was performed. DNA was obtained from cell blocks or from stained smears and subjected to NGS to analyse mutations in 50 genes. Mutations in BRAF, NRAS, KRAS and PTEN, that are known to be involved in thyroid cancer biology, were detected in seven FNA samples. The presence of a mutation in these genes was a strong indicator of cancer because five (71%) of the mutation-positive FNA samples had a malignant diagnosis after surgery. Moreover, there was only an 8% cancer risk in nodules with an indeterminate cytological diagnosis but with a negative molecular test. CONCLUSION This study demonstrates that thyroid FNA can be analysed successfully by NGS. The detection of mutations known to be involved in thyroid cancer improves the sensitivity of thyroid FNA diagnosis.
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Affiliation(s)
- Marie Le Mercier
- Department of Pathology, Erasme University Hospital, Université Libre de Bruxelles (ULB), Brussels, Belgium
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7
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Ando K, Oki E, Saeki H, Yan Z, Tsuda Y, Hidaka G, Kasagi Y, Otsu H, Kawano H, Kitao H, Morita M, Maehara Y. Discrimination of p53 immunohistochemistry-positive tumors by its staining pattern in gastric cancer. Cancer Med 2014; 4:75-83. [PMID: 25354498 PMCID: PMC4312120 DOI: 10.1002/cam4.346] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 08/13/2014] [Accepted: 08/15/2014] [Indexed: 01/04/2023] Open
Abstract
Immunohistochemistry staining of p53 is a cheap and simple method to detect aberrant function of p53. However, there are some discrepancies between the result of immunohistochemistry staining and mutation analysis. This study attempted to find a new definition of p53 staining by its staining pattern. Immunohistochemistry staining of p53 and TP53 gene mutation analysis were performed in 148 gastric cancer patients. Also SNP-CGH array analysis was conducted to four cases. Positive staining of p53 was observed in 88 (59.5%) tumors. Tumors with positive p53 staining showed malignant features compared to negative tumors. Mutation of TP53 gene was observed in 29 (19.6%) tumors with higher age and differentiated type. In positive p53 tumors, two types could be distinguished; aberrant type and scattered type. With comparison to TP53 gene mutation analysis, all the scattered type had wild-type TP53 gene (P = 0.0003). SNP-CGH array showed that scattered-type tumors had no change in the structure of chromosome 17. P53-scattered-type staining tumors may reflect a functionally active nonmutated TP53 gene. In interpretation of p53 immunohistochemistry staining, distinguishing p53-positive tumors by their staining pattern may be important in gastric cancer.
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Affiliation(s)
- Koji Ando
- Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka City, Fukuoka, 812-8582, Japan
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8
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Abstract
Thyroid nodules are common, and the accurate diagnosis of cancer or benign disease is important for the effective clinical management of patients. Molecular markers are a helpful diagnostic tool, particularly for cytologically indeterminate thyroid nodules. In the past few years, significant progress has been made in developing molecular markers for clinical use in fine-needle aspiration specimens, including gene mutation panels and gene expression classifiers. With the availability of next generation sequencing technology, gene mutation panels can be expanded to interrogate multiple genes simultaneously and to provide yet more accurate diagnostic information. In addition, recently several new molecular markers of thyroid cancer have been identified that offer diagnostic, prognostic, and therapeutic information that might be of value in guiding individualized management of patients with thyroid nodules.
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Affiliation(s)
- Susan J Hsiao
- Division of Molecular and Genomic PathologyDepartment of Pathology, University of Pittsburgh School of Medicine, 3477 Euler Way, Room 8031, Pittsburgh, Pennsylvania 15213, USA
| | - Yuri E Nikiforov
- Division of Molecular and Genomic PathologyDepartment of Pathology, University of Pittsburgh School of Medicine, 3477 Euler Way, Room 8031, Pittsburgh, Pennsylvania 15213, USA
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9
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Abstract
Molecular diagnostics offers great promise for the evaluation of cytologically indeterminate thyroid nodules. Numerous molecular genetic and immunohistochemical tests have been developed that may be performed on thyroid specimens obtained during standard fine-needle aspiration, some of which may greatly improve diagnostic yield. A sound understanding of the diagnostic performance of these tests, and how they can enhance clinical practice, is important. This article reviews the diagnostic utility of immunohistochemical and molecular testing for the clinical assessment of thyroid nodules, and makes recommendations about how these tests can be integrated into clinical practice for patients with cytologically indeterminate thyroid nodules.
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Affiliation(s)
- Sann Yu Mon
- Division of Endocrinology, University of Pittsburgh School of Medicine, 200 Lothrop Street, BST 1140, Pittsburgh, PA 15213, USA
| | - Steven P Hodak
- Division of Endocrinology, Center for Diabetes and Endocrinology, University of Pittsburgh School of Medicine, 3601 Fifth Avenue, Suite 587, Pittsburgh, PA 15213, USA.
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10
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Ohori NP, Schoedel KE. Ancillary Studies in Thyroid Cytopathology. Surg Pathol Clin 2014; 7:47-60. [PMID: 26839268 DOI: 10.1016/j.path.2013.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Recent advances in thyroid imaging, clinical evaluation, cytopathology, surgical pathology, and molecular diagnostics have contributed toward greater understanding of thyroid nodules. In particular, the development of the Bethesda System for Reporting Thyroid Cytopathology (BSRTC) has brought standardization to the field and the system dovetails well with the implementation of immunohistochemistry and molecular testing to diagnostic practice. Among the molecular strategies available, the application of the molecular panel of common genetic alterations can stratify indeterminate BSRTC diagnoses into low-risk and high-risk groups. The molecular panel markers have a high positive predictive value and therefore, the panel is considered to be a "rule-in" test. In contrast, the Afirma gene expression classifier by Veracyte Corporation is a test that has been reported to have a high negative predictive value, and therefore, considered to be a "rule-out" test. With further advances, refinements are expected to be made. In particular, the application of next-generation sequencing technology holds promise in bringing thyroid cytopathology to the next level.
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Affiliation(s)
- N Paul Ohori
- Department of Pathology, University of Pittsburgh Medical Center-Presbyterian, A610, 200 Lothrop Street, Pittsburgh, PA 15213, USA.
| | - Karen E Schoedel
- Department of Pathology, University of Pittsburgh Medical Center-Presbyterian, A610, 200 Lothrop Street, Pittsburgh, PA 15213, USA
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11
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Gupta N, Dasyam AK, Carty SE, Nikiforova MN, Ohori NP, Armstrong M, Yip L, LeBeau SO, McCoy KL, Coyne C, Stang MT, Johnson J, Ferris RL, Seethala R, Nikiforov YE, Hodak SP. RAS mutations in thyroid FNA specimens are highly predictive of predominantly low-risk follicular-pattern cancers. J Clin Endocrinol Metab 2013; 98:E914-22. [PMID: 23539734 PMCID: PMC5393462 DOI: 10.1210/jc.2012-3396] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 02/20/2013] [Indexed: 01/21/2023]
Abstract
INTRODUCTION RAS mutations are common in thyroid tumors and confer a high risk of cancer when detected in fine-needle aspiration (FNA) specimens. Specific characteristics of RAS-positive thyroid cancers are not well described. METHODS From April 2007 to April 2009, 921 consecutive patients undergoing FNA were evaluated prospectively with a panel of molecular markers. Ultrasonographic, cytological, histological, and surgical outcomes were retrospectively assessed. RESULTS Sixty-eight aspirates from 66 patients were positive for RAS mutations including 63 cytologically indeterminate (93%), 3 malignant (4%), and 2 benign (3%) specimens. Cancer was histologically confirmed in 52 of 63 aspirates (83%) including the following: 46 papillary thyroid cancers, 4 follicular thyroid cancers, 1 medullary cancer, and 1 anaplastic cancer. All 46 RAS-positive papillary thyroid cancers, including 1 metastatic cancer, had follicular variant histology papillary thyroid cancer; only 11 tumors demonstrated vascular/capsular invasion and 4 had infiltrative growth. Of 48 patients with differentiated thyroid cancer, lymph node metastasis was uncommon and bilateral cancer was present in 48%. Only 33% of malignant nodules were suspicious by preoperative ultrasonography. At a mean follow-up of 22 months, 31 of 35 differentiated thyroid cancer patients (89%) have no evidence of recurrence, 4 patients (9%) have detectable thyroglobulin, 1 patient has bone metastases, and both patients with medullary and anaplastic cancer have died. CONCLUSION Most RAS-positive thyroid cancers have indeterminate cytology, lack suspicious ultrasound features, and are histologically low-grade follicular variant histology papillary thyroid cancer. Lymph node and distant metastases are uncommon but bilateral disease is frequent. Total thyroidectomy should be considered for initial surgical management of most patients with RAS-positive FNA results. The role of prophylactic lymphadenectomy remains unclear.
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Affiliation(s)
- Nikhil Gupta
- Division of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA
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12
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Abstract
Thyroid cancer is the most common type of endocrine malignancy, with approximately 55,000 new cases diagnosed in the United States in 2012. However, thyroid nodules are much more prevalent, particularly with increased age, and only a small fraction of those are malignant. Therefore, the major clinical challenge is to reliably differentiate those nodules that are malignant and need to be treated surgically from the majority of nodules that are benign and do not require surgery. The traditional diagnostic approach to this clinical situation is ultrasound-guided fine-needle aspiration (FNA) of the thyroid nodule followed by cytologic examination, which together reliably establish the diagnosis in 70% to 80% of cases. However, in the rest of nodules the presence of cancer cannot be ruled out by FNA cytology, hampering appropriate surgical management and frequently resulting in unnecessary surgical interventions. New approaches to diagnosis of cancer in thyroid nodules are based on mutational and other molecular markers, which can be reliably detected in cells aspirated during the FNA procedure. These markers offer significant improvement in the diagnostic accuracy of FNA cytology and are poised to make a profound effect on the management of patients with thyroid nodules. In addition to the molecular markers that have recently become available for clinical use, rapid development of new sequencing techniques is expected to further improve the accuracy of cancer diagnosis in thyroid nodules and allow for a fully individualized approach to the management of patients with thyroid nodules.
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Affiliation(s)
- Yuri E Nikiforov
- Department of Pathology and Laboratory Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
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13
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Nikiforov YE, Ohori NP, Hodak SP, Carty SE, LeBeau SO, Ferris RL, Yip L, Seethala RR, Tublin ME, Stang MT, Coyne C, Johnson JT, Stewart AF, Nikiforova MN. Impact of mutational testing on the diagnosis and management of patients with cytologically indeterminate thyroid nodules: a prospective analysis of 1056 FNA samples. J Clin Endocrinol Metab 2011; 96:3390-7. [PMID: 21880806 PMCID: PMC3205883 DOI: 10.1210/jc.2011-1469] [Citation(s) in RCA: 542] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 08/03/2011] [Indexed: 12/12/2022]
Abstract
CONTEXT Thyroid nodules are common in adults, but only a small fraction of them is malignant. Fine-needle aspiration (FNA) cytology provides a definitive diagnosis of benign or malignant disease in many cases, whereas about 25% of nodules are indeterminate, hindering most appropriate management. OBJECTIVE The objective of the investigation was to study the clinical utility of molecular testing of thyroid FNA samples with indeterminate cytology. DESIGN Residual material from 1056 consecutive thyroid FNA samples with indeterminate cytology was used for prospective molecular analysis that included the assessment of cell adequacy by a newly developed PCR assay and testing for a panel of mutations consisted of BRAF V600E, NRAS codon 61, HRAS codon 61, and KRAS codons 12/13 point mutations and RET/PTC1, RET/PTC3, and PAX8/PPARγ rearrangements. RESULTS The collected material was adequate for molecular analysis in 967 samples (92%), which yielded 87 mutations including 19 BRAF, 62 RAS, 1 RET/PTC, and five PAX8/PPARγ. Four hundred seventy-nine patients who contributed 513 samples underwent surgery. In specific categories of indeterminate cytology, i.e. atypia of undetermined significance/follicular lesion of undetermined significance, follicular neoplasm/suspicious for a follicular neoplasm, and suspicious for malignant cells, the detection of any mutation conferred the risk of histologic malignancy of 88, 87, and 95%, respectively. The risk of cancer in mutation-negative nodules was 6, 14, and 28%, respectively. Of 6% of cancers in mutation-negative nodules with atypia of undetermined significance/follicular lesion of undetermined significance cytology, only 2.3% were invasive and 0.5% had extrathyroidal extension. CONCLUSION Molecular analysis for a panel of mutations has significant diagnostic value for all categories of indeterminate cytology and can be helpful for more effective clinical management of these patients.
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Affiliation(s)
- Yuri E Nikiforov
- Department of Pathology and Laboratory Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
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14
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Abstract
The beta-catenin pathway has been conclusively demonstrated to regulate differentiation and patterning in multiple model systems. In thyroid cancer, alterations are often seen in proteins that regulate beta-catenin, including those of the RAS, PI3K/AKT, and peroxisome proliferation activated receptor-gamma (PPARgamma) pathways, and evidence from the literature suggests that beta-catenin may play a direct role in the dedifferentiation commonly observed in late-stage disease. RET/PTC rearrangements are frequent in thyroid cancer and appear to be exclusive from mutational events in RAS and BRAF. Activation of AKT by phosphatidylinositide-3 kinase (PI3K), a RAS effector, results in GSK3beta phosphorylation and deactivation and subsequent beta-catenin upregulation in thyroid cancer. Activating mutations in beta-catenin, which have been demonstrated in late-stage thyroid tumors, correlate with beta-catenin nuclear localization and poor prognosis. We hypothesize that activation of the RAS, PI3K/AKT, and PPARgamma pathways ultimately impinges upon beta-catenin. We further propose that if mutations in BRAF, RAS, and RET/PTC rearrangements are mutually exclusive in certain thyroid tumors or tumor types, as has already been shown for papillary thyroid cancer, then these interconnected pathways may cooperate in the initiation and promotion of the disease. We believe that clinical benefit for thyroid cancer patients could be derived from disrupting the middle or distal pathway effectors of these pathways, such as AKT or beta-catenin.
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Affiliation(s)
- Phillip H Abbosh
- Indiana University School of Medicine, Medical Sciences, Bloomington, Indiana, USA.
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15
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Bardeesy N, Kim M, Xu J, Kim RS, Shen Q, Bosenberg MW, Wong WH, Chin L. Role of epidermal growth factor receptor signaling in RAS-driven melanoma. Mol Cell Biol 2005; 25:4176-88. [PMID: 15870287 PMCID: PMC1087708 DOI: 10.1128/mcb.25.10.4176-4188.2005] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2004] [Revised: 09/15/2004] [Accepted: 01/25/2005] [Indexed: 11/20/2022] Open
Abstract
The identification of essential genetic elements in pathways governing the maintenance of fully established tumors is critical to the development of effective antioncologic agents. Previous studies revealed an essential role for H-RAS(V12G) in melanoma maintenance in an inducible transgenic model. Here, we sought to define the molecular basis for RAS-dependent tumor maintenance through determination of the H-RAS(V12G)-directed transcriptional program and subsequent functional validation of potential signaling surrogates. The extinction of H-RAS(V12G) expression in established tumors was associated with alterations in the expression of proliferative, antiapoptotic, and angiogenic genes, a profile consistent with the observed phenotype of tumor cell proliferative arrest and death and endothelial cell apoptosis during tumor regression. In particular, these melanomas displayed a prominent RAS-dependent regulation of the epidermal growth factor (EGF) family, leading to establishment of an EGF receptor signaling loop. Genetic complementation and interference studies demonstrated that this signaling loop is essential to H-RAS(V12G)-directed tumorigenesis. Thus, this inducible tumor model system permits the identification and validation of alternative points of therapeutic intervention without neutralization of the primary genetic lesion.
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MESH Headings
- Animals
- Autocrine Communication
- Cell Line, Tumor
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Cell Transformation, Neoplastic/pathology
- ErbB Receptors/metabolism
- Gene Expression Profiling
- Gene Expression Regulation, Neoplastic
- Melanocytes/metabolism
- Melanocytes/pathology
- Melanoma/genetics
- Melanoma/metabolism
- Melanoma/pathology
- Mice
- Mice, SCID
- Mice, Transgenic
- Mitogen-Activated Protein Kinases/metabolism
- Neoplasm Transplantation
- Oncogene Protein p21(ras)/genetics
- Oncogene Protein p21(ras)/metabolism
- RNA, Neoplasm/analysis
- RNA, Neoplasm/genetics
- Signal Transduction
- Transcription, Genetic/genetics
- raf Kinases/metabolism
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Affiliation(s)
- Nabeel Bardeesy
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.
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16
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Cheng G, Meinkoth JL. Enhanced sensitivity to apoptosis in Ras-transformed thyroid cells. Oncogene 2001; 20:7334-41. [PMID: 11704863 DOI: 10.1038/sj.onc.1204928] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2001] [Revised: 08/09/2001] [Accepted: 08/15/2001] [Indexed: 11/09/2022]
Abstract
Ras mutations occur at high frequency in thyroid cancer. In vitro, the effects of Ras in thyroid cells are pleiotropic in that expression of activated Ras has been reported to stimulate proliferation and apoptosis. An understanding of the factors that contribute to the survival versus demise of Ras-transformed cells is essential to our understanding of the contribution of Ras to thyroid neoplasia and other cancers. Constitutive expression of oncogenic H-Ras sensitized Wistar rat thyroid (WRT) cells to apoptosis stimulated by multiple insults. When deprived of matrix attachment, Ras-transformed cells perished by apoptotic cell death at a high frequency. In contrast, parental cells were more resistant to suspension-induced cell death. Ras effects on anchorage-independent cell death were reproduced by a mutant protein that signals selectively to Raf-1, but not by mutant Ras that preferentially binds to RalGDS. Expression of a Ras mutant that selectively activates PI3K resulted in substantial protection from detachment-induced cell death. MAPK activity was increased in adherent Ras12V- and Ras12V35S-expressing cells, but abolished upon detachment. Interestingly, impaired MAPK activity was sufficient to stimulate apoptosis in adherent Ras-transformed cells, but not in parental cells. Treatment with a PI3K inhibitor also stimulated apoptosis selectively in Ras-transformed cells. These results demonstrate that constitutive expression of activated Ras elicits differential effects on the survival of thyroid cells. Moreover, Ras expression results in a greater dependence of thyroid cells on MAPK and PI3K activity for their survival.
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Affiliation(s)
- G Cheng
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, PA 19104-6084, USA
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17
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Abstract
Tumours derived from the thyroid follicular epithelium represent an informative model for understanding the molecular pathogenesis of multistage tumourigenesis, which is the prevailing theory on cancer development and progression nowadays. The early stages of thyroid tumour development appear to be the consequence of the activation or 'de novo' expression of several proto-oncogenes or growth factor receptors, such as ras, ret, NTRK, met, gsp and the thyrotropin (TSH) receptor. Alterations in the expression pattern of these genes are associated with the development of differentiated neoplasms, ranging from benign toxic adenomas (gsp and TSH receptor), to follicular (ras) and papillary (ret/PTC, NTRK, met) carcinomas. They may all be considered to be early events of thyroid cell transformation and, for some, experimental evidence derived from gene transfer studies supports this hypothesis. Alterations in tumour suppressor genes (p53, Rb) are associated instead with the most aggressive and poorly differentiated forms of thyroid cancer, indicating that, in the thyroid tumourigenic process, they represent late genetic events. Specific environmental factors (iodine deficiency, ionizing radiations) have been shown to play a crucial role in promoting the development of thyroid cancer, influencing both its genotypic and phenotypic features. Interestingly, a high percentage of genetic lesions causing thyroid cancer originate from gene rearrangements and chromosomal translocations (ret/PTC, NTRK, Pax-8/PPARgamma) a finding which, being a rare event in most epithelial tumours, makes the molecular pathogenesis of thyroid cancer unique. The uninterrupted flow of information on the molecular genetics of thyroid nodules and cancer will broaden the correlation between genotype and phenotype and will also provide important information for the development of more accurate preoperative diagnostic tools and more efficient treatment choices for the different forms of thyroid cancer.
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Affiliation(s)
- F Moretti
- Institute of Experimental Medicine, National Research Council
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18
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Abstract
Since 1982, Ras has been the subject of intense research scrutiny, focused on determining the role of aberrant Ras function in human cancers and defining the mechanism by which Ras mediates its actions in normal and neoplastic cells. The long-term goal has been to develop antagonists of Ras as novel approaches for cancer treatment. Although impressive strides have been made in these endeavours, and our knowledge of Ras is quite extensive, it appears that we are at the beginning, rather than at the end, of fully understanding Ras function. This review highlights new issues that have further complicated our efforts to understand Ras.
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Affiliation(s)
- J M Shields
- Depts of Pharmacology and Cell Biology, and Anatomy, University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
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19
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Abstract
The histological differentiation of thyroid carcinoma is known to correlate with prognosis. Ras oncogene mutations, which have been identified in various human cancers, have been suspected playing an important role in carcinogenesis and tumor progression. The purpose of this study was to clarify the mechanism of thyroid tumor progression, focusing on ras oncogenes. We examined ras mutations using nested polymerase chain reaction (PCR) and direct sequencing methods. The ras oncogene product was also examined immunohistochemically. Our results indicated that the incidence of ras mutations correlated with the histological differentiation of thyroid cancer. Three poorly differentiated carcinomas showed a higher rate of ras mutations than did 17 well-differentiated counterparts. Hot spots were not identified except for a relative accumulation of the N-ras gene at codon 61. There was a correlation between the immunoreactivity of the ras oncogene product and ras mutation, although the immunoreactivity of ras-p21 did not correlate with the histological differentiation. Mutation of the ras gene seemed to be one of the important events in the progression from well-differentiated carcinoma to poorly differentiated thyroid carcinoma.
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Affiliation(s)
- N Motoi
- Department of Pathology, Faculty of Medicine, University of Tokyo, Japan.
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20
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Kaserer K, Schmaus J, Bethge U, Migschitz B, Fasching S, Walch A, Herbst F, Teleky B, Wrba F. Staining patterns of p53 immunohistochemistry and their biological significance in colorectal cancer. J Pathol 2000; 190:450-6. [PMID: 10699994 DOI: 10.1002/(sici)1096-9896(200003)190:4<450::aid-path545>3.0.co;2-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Immunohistochemistry (IHC) is a cheap and rapid method to detect p53 inactivation but the results are often discordant with gene mutation analysis. This study aimed to investigate whether there is a difference in the immunohistochemical staining patterns of p53-positive cells on comparing tumours with inactivating gene mutations with those without. Tissues of 142 colorectal cancers were investigated for p53 inactivation simultaneously by IHC and gene analysis using SSCP of exons 4-9 and sequencing. In addition, tumours were investigated immunohistochemically for the expression of mdm-2 protein, known to be transcriptionally transactivated by the wild-type (wt) p53 gene. p53-positive cells of tumours without detectable p53 gene mutations were microdissected using a PALM laser microscope system and subjected to p53 sequence analysis. Among the 142 cases of colorectal cancer (male/female=88/54; mean age 66a+/-11 years, range 24-90 years), 74% (n=105) of tumours were positive by p53 IHC and mutations in the p53 gene were found in 51% (73 patients). In 16% (12 patients) with mutations in the p53 gene, IHC for p53 was negative. In tumours with mutations in the p53 gene and positive p53 IHC, staining of all nuclei of the tumour was more frequently (57/61, 93%) found than in tumours without p53 gene mutations, where staining of scattered single cells was predominantly seen (29/44, 66%; p<0.0001). mdm-2 positivity (n=33) showed only staining of scattered single cells, predominantly (24/33, 82%; p<0.0001) in tumours without gene mutations. Single cell microdissection followed by mutation analysis of scattered p53-positive cells revealed no gene mutations. A scattered positive immunohistochemical reactivity of p53 in colorectal cancer cells might therefore represent a functionally active non-mutated p53 gene and should not be considered as a marker of gene mutation and inactivation.
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Affiliation(s)
- K Kaserer
- Department of Clinical Pathology, University of Vienna, Medical School, Austria.
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21
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Best CJ, Tanzer LR, Phelps PC, Merriman RL, Boder GG, Trump BF, Elliget KA. H-ras-transformed NRK-52E renal epithelial cells have altered growth, morphology, and cytoskeletal structure that correlates with renal cell carcinoma in vivo. In Vitro Cell Dev Biol Anim 1999; 35:205-14. [PMID: 10478800 DOI: 10.1007/s11626-999-0028-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We studied the effect of the ras oncogene on the growth kinetics, morphology, cytoskeletal structure, and tumorigenicity of the widely used NRK-52E rat kidney epithelial cell line and two H-ras oncogene-transformed cell lines, H/1.2-NRK-52E (H/1.2) and H/6.1-NRK-52E (H/6.1). Population doubling times of NRK-52E, H/1.2, and H/6.1 cells were 28, 26, and 24 h, respectively, with the transformed cells reaching higher saturation densities than the parent cells. NRK-52E cells had typical epithelial morphology with growth in colonies. H/1.2 and H/6.1 cell colonies were more closely packed, highly condensed, and had increased plasma membrane ruffling compared to parent cell colonies. NRK-52E cells showed microfilament, microtubule, and intermediate filament networks typical of epithelial cells, while H/1.2 and H/6.1 cells showed altered cytoskeleton architecture, with decreased stress fibers and increased microtubule and intermediate filament staining at the microtubule organizing center. H/1.2 and H/6.1 cells proliferated in an in vitro soft agar transformation assay, indicating anchorage-independence, and rapidly formed tumors in vivo with characteristics of renal cell carcinoma, including mixed populations of sarcomatoid, granular, and clear cells. H/6.1 cells consistently showed more extensive alterations of growth kinetics, morphology, and cytoskeleton than H/1.2 cells, and formed tumors of a more aggressive phenotype. These data suggest that analysis of renal cell characteristics in vitro may have potential in predicting tumor behavior in vivo, and significantly contribute to the utility of these cell lines as in vitro models for examining renal epithelial cell biology and the role of the ras proto-oncogene in signal transduction involving the cytoskeleton.
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Affiliation(s)
- C J Best
- Department of Pathology, University of Maryland School of Medicine, Baltimore 21201, USA
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22
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Miller MJ, Rioux L, Prendergast GV, Cannon S, White MA, Meinkoth JL. Differential effects of protein kinase A on Ras effector pathways. Mol Cell Biol 1998; 18:3718-26. [PMID: 9632754 PMCID: PMC108954 DOI: 10.1128/mcb.18.7.3718] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/1997] [Accepted: 03/26/1998] [Indexed: 02/07/2023] Open
Abstract
Ras mutants with the ability to interact with different effectors have played a critical role in the identification of Ras-dependent signaling pathways. We used two mutants, RasS35 and RasG37, which differ in their ability to bind Raf-1, to examine Ras-dependent signaling in thyroid epithelial cells. Wistar rat thyroid cells are dependent upon thyrotropin (TSH) for growth. Although TSH-stimulated mitogenesis requires Ras, TSH activates protein kinase A (PKA) and downregulates signaling through Raf and the mitogen-activated protein kinase (MAPK) cascade. Cells expressing RasS35, a mutant which binds Raf, or RasG37, a mutant which binds RalGDS, exhibited TSH-independent proliferation. RasS35 stimulated morphological transformation and anchorage-independent growth. RasG37 stimulated proliferation but not transformation as measured by these indices. TSH exerted markedly different effects on the Ras mutants and transiently repressed MAPK phosphorylation in RasS35-expressing cells. In contrast, TSH stimulated MAPK phosphorylation and growth in cells expressing RasG37. The Ras mutants, in turn, exerted differential effects on TSH signaling. RasS35 abolished TSH-stimulated changes in cell morphology and thyroglobulin expression, while RasG37 had no effect on these activities. Together, the data indicate that cross talk between Ras and PKA discriminates between distinct Ras effector pathways.
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Affiliation(s)
- M J Miller
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6084, USA
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23
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Li X, Tsuji T, Wen S, Mimura Y, Sasaki K, Shinozaki F. Detection of numeric abnormalities of chromosome 17 and p53 deletions by fluorescence in situ hybridization in pleomorphic adenomas and carcinomas in pleomorphic adenoma. Correlation with p53 expression. Cancer 1997; 79:2314-9. [PMID: 9191518 DOI: 10.1002/(sici)1097-0142(19970615)79:12<2314::aid-cncr4>3.0.co;2-l] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND A fluorescence in situ hybridization (FISH) technique using specific DNA probes allows for the detection of chromosomal aberrations and gene deletions and gains, even in interphase nuclei in human solid tumors. A high frequency of aberrations of chromosome 17 and mutation of the p53 gene have been reported in some human tumors. The correlation of p53 expression with abnormalities of chromosome 17 and p53 gene deletion in salivary gland tumors has not yet been investigated. METHODS The authors analyzed the numeric aberrations of chromosome 17 and p53 gene deletions in 11 paraffin embedded pleomorphic adenomas (PA) and 9 carcinomas in pleomorphic adenoma (CIPA), using FISH techniques. The centromere specific DNA probe for chromosome 17 and p53 cosmid DNA probe was used. The aberrations of chromosome 17 and p53 deletion were correlated with immunohistochemical detection of p53 protein. RESULTS Monosomy 17 was detected in 30.8% of CIPA cells and 29.6% of PA cells, and polysomy 17 was detected in 19.6% of CIPA cells and 9.6% of PA cells. p53 protein expression was observed in 6 of 9 CIPA specimens (66.7%) and 2 of 75 PA specimens (2.7%). Deletion of the p53 gene was frequent in p53 protein positive specimens. A statistically significant correlation existed between p53 protein expression and polysomy 17 (P = 0.0417). CONCLUSIONS It was observed that loss of chromosome 17 may occur in PA before its transformation to carcinoma. p53 expression was frequently associated with deletion of the p53 gene as detected by FISH. Polysomy 17 was more frequent in CIPA than PA and was associated with mutation of p53.
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Affiliation(s)
- X Li
- Department of Oral and Maxillofacial Surgery, Yamaguchi University School of Medicine, Ube, Japan
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24
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Uchiyama M, Iwasaka T, Matsuo N, Hachisuga T, Mori M, Sugimori H. Correlation between human papillomavirus positivity and p53 gene overexpression in adenocarcinoma of the uterine cervix. Gynecol Oncol 1997; 65:23-9. [PMID: 9103386 DOI: 10.1006/gyno.1997.4613] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In the pathogenesis of cervical squamous cell carcinoma, an inverse correlation between human papillomavirus (HPV) infection and mutation of the p53 anti-oncogene has been suggested. Much less is known of a possible correlation in the case of adenocarcinoma of cervix. Twenty-five cervical adenocarcinomas and 7 adenosquamous carcinomas were analyzed for presence of HPV DNA sequences and overexpression of the p53 gene. Polymerase chain reaction revealed that 11 were positive for HPV DNA (34%). Seven were positive for HPV 16 and 5 for HPV 18. A mixed infection with HPV 16 and 18 was observed in 1 case. Patients with HPV-positive carcinoma were significantly younger than those with HPV-negative carcinoma (43 +/- 13.3 years versus 57 +/- 17.4 years, P = 0.01). Immunohistochemical staining showed that p53 was overexpressed in 11 of 32 cases (34%). Overexpression of the p53 gene was found in only 1 of 11 HPV-positive cases (9%) yet was evident in 10 of 21 HPV-negative cases (48%). This inverse association was statistically significant (P < 0.05). Prognostic analysis revealed that HPV-negative adenocarcinomas had a poorer prognosis than HPV-positive cases (P < 0.01) and that tumors with p53 overexpression also had a poorer prognosis than those without such overexpression (P < 0.01). Our observations suggest that HPV-negative or p53-positive adenocarcinomas may be a biologically distinct subset with a poorer prognosis.
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MESH Headings
- Adenocarcinoma/chemistry
- Adenocarcinoma/complications
- Adenocarcinoma/genetics
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Base Sequence
- Carcinoma, Adenosquamous/chemistry
- Carcinoma, Adenosquamous/complications
- Carcinoma, Adenosquamous/genetics
- Cervix Uteri/chemistry
- Cervix Uteri/metabolism
- Cervix Uteri/virology
- DNA, Neoplasm/analysis
- DNA, Neoplasm/chemistry
- DNA, Neoplasm/genetics
- DNA, Viral/analysis
- DNA, Viral/chemistry
- DNA, Viral/genetics
- Female
- Gene Expression Regulation, Neoplastic
- Humans
- Immunohistochemistry
- Middle Aged
- Mutation
- Papillomaviridae/genetics
- Papillomaviridae/isolation & purification
- Papillomavirus Infections/complications
- Papillomavirus Infections/metabolism
- Polymerase Chain Reaction
- Prognosis
- Tumor Suppressor Protein p53/analysis
- Tumor Suppressor Protein p53/genetics
- Tumor Suppressor Protein p53/metabolism
- Tumor Virus Infections/complications
- Tumor Virus Infections/metabolism
- Uterine Cervical Neoplasms/chemistry
- Uterine Cervical Neoplasms/complications
- Uterine Cervical Neoplasms/genetics
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Affiliation(s)
- M Uchiyama
- Department of Obstetrics and Gynecology, Saga Medical School, Japan
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25
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Abstract
It has been suggested that an important step in the progression of some epithelial tumours is the loss of responsiveness to the growth-inhibitory effects of transforming growth factor beta (TGFbeta). Here we describe the use of a model of thyroid tumorigenesis to investigate this question. Seven genetically closely related epithelial cell lines were derived following infection of primary cultures of rat thyroid epithelium with retroviral vectors encoding mutant ras. A strong negative correlation (p < 0.001) was found between the responsiveness of the lines to TGFbeta growth inhibition in vitro and their tumorigenicity in nude mice. Whereas TGFbeta-unresponsive and TGFbeta-stimulated lines formed rapidly growing, poorly differentiated tumours at all injection sites, cells that retained a partial inhibitory response formed much more slowly growing tumours, which showed a high degree of glandular differentiation. A line which retained full inhibition by TGFbeta formed slowly growing tumours at only 30% of injection sites, and cells explanted from these tumours subsequently showed a much reduced TGFbeta response in vitro. Our data using thyroid cells thus greatly strengthen the suggestion from previous studies that loss of growth inhibition by TGFbeta is associated with malignant progression of epithelial tumours. We also present an experimental model of papillary thyroid cancer which may prove useful in identifying the molecular changes involved in progression to the anaplastic form of the disease.
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Affiliation(s)
- J P Blaydes
- Department of Pathology, University of Wales, Cardiff, United Kingdom
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26
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Bartsch D, Shevlin DW, Tung WS, Kisker O, Wells SA, Goodfellow PJ. Frequent mutations of CDKN2 in primary pancreatic adenocarcinomas. Genes Chromosomes Cancer 1995; 14:189-95. [PMID: 8589035 DOI: 10.1002/gcc.2870140306] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The gene encoding the cell-cycle regulatory protein p16, CDKN2, is localized on chromosome band 9p21. CDKN2 is frequently deleted or mutated in a variety of tumor cell lines, including pancreatic cancer cell lines and xenografts, as well as in some primary tumors. We examined 32 primary pancreatic adenocarcinomas for CDKN2 mutations and for loss of heterozygosity of 9p21 sequences to assess the role of CDKN2 in pancreatic carcinogenesis. Single-strand conformation variant analysis (SSCV) and direct sequencing of the variants revealed somatic CDKN2 mutations in 11 of 32 tumors (five frame-shift mutations, five nonsense mutations, and one missense mutation). One tumor appeared to be characterized by homozygous deletion of CDKN2. These results suggest that CDKN2 plays an important role during tumorigenesis or tumor progression in a significant proportion of pancreatic adenocarcinomas.
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Affiliation(s)
- D Bartsch
- Department of Surgery, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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27
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Affiliation(s)
- D Wynford-Thomas
- Department of Pathology, University of Wales College of Medicine, Cardiff, United Kingdom
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28
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Abstract
One hundred and thirty-one thyroid tumours were examined immunohistochemically for expression of retinoblastoma (RB) and p53 protein. The results demonstrate that RB protein is not lost in any cases, indicating that inactivation of the RB gene is unlikely to play a central role in the pathogenesis of thyroid tumours. Eighteen of 24 (75 per cent) undifferentiated carcinomas, 6 of 32 (19 per cent) papillary carcinomas, 5 of 29 (17 per cent) follicular carcinomas, and 6 of 46 (13 per cent) medullary carcinomas showed p53 protein nuclear staining. In 46 per cent of the undifferentiated carcinomas many of the tumour cells had accumulated p53 protein, whereas in the other positive cases less than 5 per cent of the cells had increased p53 protein levels. Our results strongly suggest that p53 protein abnormalities play a crucial role in the progression of well-differentiated to undifferentiated thyroid carcinomas.
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Affiliation(s)
- R Holm
- Department of Pathology, Norwegian Radium Hospital, Oslo
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29
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Abstract
We describe the existence in normal human primary thyroid cultures of a hitherto unrecognised sub-population of epithelial cells. This variant phenotype is characterised by squamoid morphology, absence of thyroglobulin, and an altered profile of intermediate filament expression. We suggest that these cells are derived from scattered foci of squamous metaplasia present in the normal gland. Although they are initially present at a frequency of less than 10(-4), their very high proliferative capacity enables them to outgrow the 'classical' follicular cells and confers a much increased capacity for gene transduction. Recognition of these cells is therefore crucial in the interpretation of long-term thyroid culture experiments and those involving in vitro gene transfer.
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Affiliation(s)
- J A Bond
- Department of Pathology, University of Wales College of Medicine, Heath Park, Cardiff, UK
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30
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Abstract
Epidemiological studies of heritable cancer have demonstrated that cancer predisposition is a dominant trait; these studies have also predicted the recessive outcome of the neoplastic process. Biochemical studies of dominantly heritable cancer have demonstrated the relevance of systemic effects. The systemic effects are presumably due to a dominant mutation at the "initiator locus." Collectively they define cancer initiation at the cellular level (as described in this review). Molecular biological studies have demonstrated that cancer progression and the appearance of clinical cancer occur through an accumulation of recessive mutations at critical loci. We must continue to try to define not only the inherited and acquired gene defects that initiate the neoplastic state but also the subsequent genetic alterations and biomarkers involved in tumor progression. These genetic defects are already proving useful in diagnosis and prognostication. The hope is that these biomarkers may be useful for designing specific differentiation therapy.
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Affiliation(s)
- L Kopelovich
- Laboratory of Cancer Genetics and Cancer Prevention, VA Medical Center, Bay Pines, Florida 33504
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