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The Journal of Clinical Endocrinology & Metabolism Vol. 89, No. 9 4267-4271
Copyright © 2004 by The Endocrine Society

Special Feature

BRAF Mutations Are Not a Major Event in Post-Chernobyl Childhood Thyroid Carcinomas

Jorge Lima, Vítor Trovisco, Paula Soares, Valdemar Máximo, João Magalhães, Giuliana Salvatore, Massimo Santoro, Tatyana Bogdanova, Mykola Tronko, Alexander Abrosimov, Steve Jeremiah, Gerry Thomas, Dillwyn Williams and Manuel Sobrinho-Simões

Institute of Molecular Pathology and Immunology (J.L., V.T., P.S., V.M., J.M., A.A., M.S.-S.) and Medical Faculty (J.L., V.T., P.S., M.S.-S.), University of Porto, 4200-465 Porto, Portugal; Department of Pathology (J.M., M.S.-S.), Hospital S. João, 4200 Porto, Portugal; Centro di Endocrinologia ed Oncologia Sperimentale del Consiglio Nazionale delle Ricerche, Dipartimento di Biologia e Patologia Cellulare e Molecolare (G.S., M.S.), Università di Napoli Federico II, 80137 Italia; Institute of Endocrinology and Metabolism (T.B., M.T.), 254114 Kiev, Ukraine; Medical Radiological Research Centre of Russian Academy of Medical Sciences (A.A.), 249020 Obninsk, Russian Federation; South West Wales Cancer Institute (S.J., G.T.), Swansea Clinical School, Singleton Hospital, SA2 8QA Swansea, United Kingdom; and Strangeways Research Laboratory (D.W.), University of Cambridge, CB1 8RN Cambridge, United Kingdom

Address all correspondence and requests for reprints to: Dr. Manuel Sobrinho-Simões, Institute of Molecular Pathology and Immunology, University of Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto, Portugal. E-mail: ssimoes{at}ipatimup.pt.


   Abstract
Top
 Abstract
Introduction
 Patients and Methods
 Results
 Discussion
 References
 
The BRAF gene has been shown to be a major target for mutations in papillary thyroid carcinoma (PTC) (36–69%), which forms almost all of the over 2000 cases of thyroid carcinoma that have occurred in Chernobyl. BRAF is activated by point mutation, and were it to occur at a high frequency in Chernobyl-related tumors, it would challenge the dominant role of double-strand breaks in radiation-induced PTC. In a previous study, we detected the BRAF V600E mutation in 46% (23 of 50) of sporadic adult PTC. Using the same methodology, we have analyzed 34 post-Chernobyl PTC and detected RET/PTC rearrangements in 14 (41%) and BRAF mutations (V600E) in four (12%). These two alterations did not coexist in any PTCs. The mean age at exposure of patients with PTC showing BRAF mutation was higher than that of patients with tumors without BRAF mutation irrespective of their RET status. We have also analyzed 17 sporadic cases of childhood PTC and found that only one (6%) harbored the BRAF V600E mutation. We conclude that the frequency of BRAF mutations is significantly lower (P = 0.0008) in post-Chernobyl PTC than in adult sporadic PTC, whereas no significant difference was found between post-Chernobyl and sporadic childhood PTCs.


   Introduction
Top
 Abstract
 Introduction
Patients and Methods
 Results
 Discussion
 References
 
MOLECULAR BIOLOGICAL STUDIES of post-Chernobyl thyroid tumors revealed a high prevalence of rearrangements of the RET protooncogene (57–76%) in papillary thyroid carcinoma (PTC) (1, 2). RET/PTC3 was found to be the most frequent type of rearrangement and was also associated with more aggressive tumors (1, 2). Studies on the frequency of NTRK1 rearrangements, which are also associated with PTC, demonstrated that this type of rearrangement was present in a low percentage in post-Chernobyl PTC (3). Genes frequently activated by point mutation in human cancer (P53 and H-, N-, and K-RAS) were absent or only rarely involved in these radiation-induced tumors (4, 5, 6). Thus, RET/PTC rearrangements are, to date, the only genetic event consistently associated with post-Chernobyl PTC.

Recently, mutations in BRAF were found in various types of sporadic human cancers, including melanomas, thyroid cancer, colon cancer, lung cancer, and ovarian cancer (7, 8, 9, 10, 11, 12, 13, 14, 15), as well as benign nevi lesions (16). BRAF belongs to the RAF family of kinases, which includes two other isoforms: ARAF and CRAF (RAF-1). BRAF has a serine/threonine kinase activity and is located downstream of RAS and upstream of MEK in the classic MAPK cascade (17, 18, 19). Screening studies revealed a hotspot at position 1799, resulting in a substitution of a valine for a glutamate at residue 600 [previously position 1796 and residue 599, but according to recent data sequence, numbering of codons and nucleotides after exon 1 of BRAF were changed by +1 and +3, respectively (20)]. This mutation is located in the activating segment of BRAF and represents the vast majority of tumor-associated BRAF mutations (12). Functional studies led to the conclusion that this mutation resulted in a 70-to 138-fold increase of the activity of BRAF, independently of RAS stimulation, predicted to result in a proliferation stimulus to the cells and, ultimately, in cancer (12). Our group has shown that 46% (23 of 50) of sporadic adult PTCs harbored the BRAF V600E mutation (14) and, more recently, that BRAF V600E mutation appeared to be restricted to PTCs displaying a papillary or a mixed papillary/follicular growth pattern (21). The frequency of BRAF mutations in sporadic adult PTC is the second highest reported in human cancer, after melanoma (12, 16). These results fit with those published by other groups who found the V600E mutation in frequencies varying from 29–69% of PTCs (13, 15, 22, 23, 24, 25). In the series of sporadic PTCs we have previously published (14), RET/PTC rearrangements were present in 18% of cases and did not coexist with BRAF V600E mutation in any case. A similar finding was reported by Kimura et al. (13), who detected RET/PTC rearrangements in 16% of their cases. The same holds true regarding RAS mutations that did not coexist with BRAF mutations in our series nor in that of Kimura et al. (13, 14).

The results we and other groups obtained in sporadic thyroid cancer support the claim that BRAF mutations are a major event in sporadic thyroid papillary carcinogenesis (13, 14, 15, 21, 22, 23, 24, 25). However, to date, only one study has analyzed specifically radiation-induced PTC that occurred as a consequence of the Chernobyl accident. In this study, the authors found a similar frequency of BRAF mutations in these radiation-induced PTCs (three of 10, 30%) when compared with sporadic PTCs (29–69%), even though a lower frequency (one of five, 20%) was found when analyzing only radiation-induced PTCs in children (26). We undertook the present study to determine the frequency of such mutations in a series of post-Chernobyl childhood thyroid tumors, to find out whether or not the inverse relationship between BRAF mutations and RET/PTC rearrangements observed in sporadic thyroid tumors is also present in cases occurring in a radiation setting and to increase our understanding of the mechanisms involved in radiation carcinogenesis.


   Patients and Methods
Top
 Abstract
 Introduction
 Patients and Methods
Results
 Discussion
 References
 
We analyzed 34 cases of PTC (nine males and 25 females) and 11 follicular adenomas (FAs) (two males and nine females) that occurred in contaminated regions in Ukraine. For each case of PTC and each FA, we studied DNA and RNA extracted from frozen samples of tumor tissue and adjacent normal thyroid tissue. The pathology of the samples was confirmed by frozen section before homogenization and nucleic acid extraction. DNA from the peripheral blood of 15 PTCs and four FAs was also available and studied. The material we studied (DNA and RNA from tumor and normal thyroid tissue and blood samples) was obtained from the Chernobyl Tissue Bank (http://www.chernobyltissuebank.com). We have also studied DNA from 17 paraffin-embedded cases of sporadic PTC that occurred in nonexposed children under the age of 18 [12 cases from the files of Hospital S. João in Porto and five cases from a survey of childhood thyroid cancer in England and Wales (27)].

The diagnosis of all the Chernobyl cases was confirmed by the members of the Pathology Panel of the Chernobyl Tumor Bank. The diagnosis of the nonexposed cases and the subclassification of all the cases were carried out by at least two of four experienced thyroid pathologists among the authors (T.B., J.M., D.W., and M.S.-S.).

BRAF mutation analysis

To screen for BRAF mutations, we analyzed DNA from tumor tissue and, when available, adjacent thyroid tissue and peripheral blood of the patients. We studied the two regions of BRAF where mutations have been identified, G loop region and activation segment, which are encoded by exons 11 and 15, respectively. Both exons were amplified by PCR using conditions described elsewhere (12). The amplicons were then subjected to single strand conformation polymorphism (SSCP) analysis: PCR products of BRAF exons 11 and 15 were diluted 1:1 with loading buffer (95% formamide, 0.05% bromophenol blue, and 0.05% xylene cyanol), denatured at 98 C for 10 min, and cooled on ice for 5 min. Electrophoresis of the denatured PCR products was carried out in nondenaturing 0.8x mutation detection enhancement gels (BMA, Rockland, ME) at 180 V and 8 C for 15 h. PCR/SSCP products were visualized by standard DNA silver staining.

BRAF sequencing analysis

Whenever a sample presented aberrant bands in the SSCP analysis, these bands were excised from the mutation detection enhancement gel, and the PCR products were eluted and used as template for a second PCR using the aforementioned PCR conditions. PCR products from this second PCR were subjected to a purifying treatment using Exonuclease I (New England Biolabs, Beverly, MA) and Shrimp Alkaline Phosphatase (Amersham Biosciences, Piscataway, NJ) and subjected to automatic sequencing, using ABI Prism dGTP BigDye Terminator Ready Reaction Kit (Perkin-Elmer, Foster City, CA) and an ABI prism 3100 Genetic Analyzer (Perkin-Elmer). Sequencing was performed on both strands using the aforementioned primers. Whenever an alteration was identified by sequencing, the DNA sample was subjected to a second mutation analysis, including PCR amplification from genomic DNA of the exon containing the alteration, SSCP analysis, and sequencing of the amplified fragment, to confirm the existence of the alteration.

In both SSCP and sequencing analysis, we used the TPC-1 cell line as a negative control for BRAF mutations and the HT-29 cell line as a positive control for BRAF V600E mutation.

Expression of RET/PTC1 and RET/PTC3

The prevalence of RET/PTC1 and RET/PTC3 rearrangements were analyzed by using the RT-PCR assay. A common antisense and different forward oligodeoxynucleotides, specific for the H4 and RFG genes, were used as before (6). The sequence of the forward primers used were: RET/PTC1, 5'-ATTGTCATCTCGCCGTTC-3' (nucleotides 196–214 of RET/PTC1); and RET/PTC3, 5'-AAGCAAACCTGCCAGTGG-3' (nucleotides 697–714 of RET/PTC3). The sequence of the reverse primer was: 5'-TGCTTCAGGACGTTGAAC-3' (nucleotides 543–561 of RET/PTC1). One microgram of RNA was reverse transcribed and subsequently subjected to 35 cycles of PCR with a thermal cycler (Perkin-Elmer-Cetus). The product of the reaction was analyzed on a 2% agarose gel and hybridized with a RET probe covering the TK domain. The quality of the RNA samples was assayed by amplifying the HPRT mRNA. The HPRT specific primers were: forward primer, 5'-CCTGCTGGATTACATCAAAGCACTG-3', corresponding to nucleotides 316–340 of the third exon of the human gene; and reverse primer, 5'-CCTGAAGTATTCATTATAGTCTCAAGG-3', corresponding to nucleotides 685–661 of the eighth exon of the human gene.

Statistical analysis

The statistical analysis of the results was performed using the {chi}2 test with the Yates correction and Fisher’s exact test. A P value < 0.05 was considered statistically significant.

Informed consent

Informed consent was obtained in accordance with National Institutes of Health guidelines for all the tissues from the Chernobyl-related tumors. The use of spare sections from the paraffin blocks of the sporadic tumors was in accordance with the guidelines of the ethical committee of the University Hospital of S. João (Porto, Portugal).


   Results
Top
 Abstract
 Introduction
 Patients and Methods
 Results
Discussion
 References
 
We detected the presence of a BRAF mutation in four of 34 post-Chernobyl PTCs (12%); all four cases showed the 1799T-A mutation in exon 15 of BRAF, leading to substitution of a valine for glutamate at position 600 (Table 1Go). The four post-Chernobyl PTCs with BRAF mutation displayed signs of local invasiveness; vascular invasion or distant metastasis were not detected, and only one showed cervical node metastasis. The BRAF V600E mutation was also detected in one of 17 PTCs (6%) that occurred in nonexposed children (Table 1Go). The mutation was detected in the tumor tissue and was not present in normal thyroid samples or peripheral blood.


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  		TABLE 1. Prevalence of RET/PTC rearrangements and BRAF mutations in post-Chernobyl (irradiated) tumors and in sporadic childhood PTC

 
The study of RET/PTC rearrangements revealed that 14 of 34 post-Chernobyl PTCs (41%) were found to possess either RET/PTC1 or RET/PTC3 (Table 1Go). BRAF V600E mutation and RET/PTC rearrangements did not coexist in any of the cases.

Three of the four post-Chernobyl cases presenting the V600E mutation were conventional forms of PTC with a predominantly papillary growth pattern, and the remaining case was a follicular variant of PTC (Table 2Go). No solid variant of PTC displayed the BRAF V600E mutation, in contrast to the occurrence of RET/PTC rearrangements in four of the eight cases of this variant (Table 2Go).


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  		TABLE 2. Prevalence of RET/PTC rearrangements and BRAF mutations in conventional, solid variant, and follicular variant of post-Chernobyl PTC

 
The only sporadic childhood PTC presenting the V600E mutation displayed a predominant papillary growth pattern. Ten other cases with this subtype lacked a BRAF mutation, as did all six cases of the follicular variant of PTC. There was no case of solid variant of PTC in the group of sporadic childhood PTC.

Among the five cases who were oldest at time of exposure, three showed a BRAF mutation, whereas only one showed a RET/PTC rearrangement. Patients with RET/PTC rearrangements had the lowest mean age at exposure of any group (Table 3Go).


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  		TABLE 3. Female to male ratio and age at the time of accident and operation of patients with post-Chernobyl PTC

 
Analysis of the 11 FA revealed one tumor (9%) presenting a BRAF mutation in codon 601, which resulted in a substitution of a lysine for a glutamate; no V600E mutation was disclosed (Table 1Go).

No mutations in exon 11 of BRAF were found in any of 45 post-Chernobyl tumors (Table 1Go).


   Discussion
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Discussion
References
 
The Chernobyl accident resulted in the highest number of a specific type of human cancer (PTC) that occurred as a consequence of a single event in a single place, at a specific time, ever recorded (28). This dramatic increase in the number of thyroid cancers in Belarus, Ukraine, and parts of the Russian Federation, which began just 4 years after the Chernobyl accident, has provided a unique chance to study the molecular pathology of thyroid cancer, specifically radiation-induced thyroid cancer.

It is well known that sporadic PTCs are commonly associated with rearrangements of the RET protooncogene (3–60%) (29). In the post-Chernobyl irradiation setting, this association is even more evident; 57–76% of cases have been reported to show RET/PTC rearrangements, with RET/PTC3 and RET/PTC1 being the most prevalent (1, 2). RET/PTC3 was found in an unusually high frequency in the earlier tumors and was associated with a solid pattern of growth and clinical aggressiveness (1). It is still unclear whether this apparent high frequency of RET/PTC rearrangements is related to radiation or to age; a similar frequency of RET/PTC rearrangement was found in unexposed children with papillary carcinoma in England and Wales (30). Nevertheless, there is still a high percentage of post-Chernobyl PTCs with no genetic alterations yet disclosed.

After the discovery of BRAF mutations as a major event in sporadic PTC (13, 14, 15), we were interested both to assess the prevalence of BRAF mutations in a cohort of post-Chernobyl tumors and sporadic childhood PTCs and to ascertain whether BRAF mutations and RET/PTC rearrangements were mutually exclusive. Our results revealed a significantly lower percentage of BRAF mutations in post-Chernobyl PTC (12%) than in our own series of sporadic adult PTC studied with the same techniques (46%) (P = 0.0009) (14), whereas the opposite occurs (as one would expect) regarding the prevalence of RET/PTC rearrangement (14). The frequency of BRAF mutations in sporadic adult PTC in our series (14) is similar to most of those reported in other studies (Table 4Go).


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  		TABLE 4. Prevalence of BRAF mutations and RET/PTC rearrangements in several studies reported in the literature

 
The low frequency of BRAF mutations in post-Chernobyl tumors could reflect the nature of the etiological agent. Ionizing radiation is known to be particularly effective in inducing DNA double-strand breaks, rather than point mutations, although the latter do occur (31). Thus, our results could be interpreted as supporting the view that a major mechanism of thyroid carcinogenesis in Chernobyl-related thyroid carcinomas is the formation of rearrangements after radiation-induced double-strand break in DNA. The presence of 12% of BRAF-positive cases could represent the minor effect of radiation in inducing point mutations, or it could be related to the normal background incidence. The incidence of thyroid carcinoma in northern Ukraine has increased about 10-fold, so that about 10% of the tumors could represent sporadic nonradiation-induced tumors. The rapid drop in sensitivity to radiation carcinogenesis in the thyroid with increasing age at exposure and the increasing sporadic incidence with increasing age in childhood and adolescence suggest that the sporadic cases are more likely to be found among those who were older at exposure. Although the number of cases is very limited, it is interesting that the BRAF-positive cases were on average older at exposure than the BRAF-negative cases. Some could well represent sporadic cases, thus strengthening the relationship between radiation and rearrangements.

However, there are other interrelated possibilities that must be considered. The earlier BRAF studies have been carried out in adult patients, whereas our Chernobyl-related studies have included only children and adolescents. To investigate possible age-related effects, we have compared the results in post-Chernobyl PTC with the findings in 17 sporadic PTCs that occurred in children under 18 yr. In this setting, we observed that only one PTC of 17 (6%) harbored the BRAF V600E mutation. This frequency is similar to that observed in post-Chernobyl PTC but significantly lower than that of sporadic PTC occurring in adults (P = 0.0016) (14).

Our findings revealed that BRAF mutations are usually rare in sporadic childhood thyroid carcinoma, both in an irradiation setting and in sporadic tumors. Therefore, it is possible that the route to thyroid carcinogenesis that involves a BRAF mutation may have a longer latent period than the route involving a rearrangement. This explanation can only be tested by waiting another few years and then reassessing the frequency of BRAF mutations and RET/PTC rearrangements in adult Chernobyl-related thyroid carcinomas and in the more readily available age-matched adult patients.

In addition, our study has confirmed codon 600 (nucleotide 1799) as a mutational hotspot in BRAF coding sequence and the V600E mutation as specific to PTC. As has been observed in other studies (13, 14, 24), no mutation was found in BRAF exon 11 in PTC, nor in FA. Interestingly, we observed in one FA a mutation in codon 601 (K601E); an identical mutation had been previously detected in one sporadic FA (14) as well as in 9% of cases of follicular variant of PTC (21). Further studies are needed to assess the frequency and the putative clinical significance of this mutation in both benign and malignant thyroid tumors.

Our findings show that BRAF mutations are much less common in PTC in children and adolescents, both sporadic and radiation related, than in any of the reported series of sporadic PTC. They emphasize the importance of taking age into account when comparing mutation frequency in different series. Continuing study of the Chernobyl-related tumors and of the relationship between the frequency of BRAF mutation and age in sporadic tumors is needed to ascertain whether the etiological agent, latent period, and/or age is the cause of this marked difference in mutation frequency.


   Acknowledgments
 
We thank the Chernobyl Tissue Bank (http://www.chernobyltissuebank.com) for providing the material used in this study.


   Footnotes
 
This work was partially supported by the Portuguese Science and Technology Foundation (Ph.D. Grants SFRH/BD/8425/2002 to J.L. and SFRH/BD/13055/2003 to V.T. and Postdoctoral Grant SFRH/BPD/14594/2003 to V.M.) and by further funding from the same source (Project Programa Operacional Ciência Tecnologia e Inovação/Ciências Biomédicas e Oncológicas/47477/2002).

Abbreviations: FA, Follicular adenoma; PTC, papillary thyroid carcinoma; SSCP, single strand conformation polymorphism.

Received December 30, 2003.

Accepted April 16, 2004.


   References
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Discussion
 References
 

  1. Thomas GA, Bunnell H, Cook HA, Williams ED, Nerovnya A, Cherstvoy ED, Tronko ND, Bogdanova TI, Chiappetta G, Viglietto G, Pentimalli F, Salvatore G, Fusco A, Santoro M, Vecchio G 1999 High prevalence of RET/PTC rearrangements in Ukrainian and Belarussian post-Chernobyl thyroid papillary carcinomas: a strong correlation between RET/PTC3 and the solid-follicular variant. J Clin Endocrinol Metab 84:4232–4238[Abstract/Free Full Text]
  2. Nikiforov YE, Rowland JM, Bove KE, Monforte-Munoz H, Fagin JA 1997 Distinct pattern of ret oncogene rearrangements in morphological variants of radiation-induced and sporadic thyroid papillary carcinomas in children. Cancer Res 57:1690–1694[Abstract/Free Full Text]
  3. Beimfohr C, Klugbauer S, Demidchik EP, Lengfelder E, Rabes HM 1999 NTRK1 re-arrangement in papillary thyroid carcinomas of children after the Chernobyl reactor accident. Int J Cancer 80:842–847[CrossRef][Medline]
  4. Suchy B, Waldmann V, Klugbauer S, Rabes HM 1998 Absence of RAS and p53 mutations in thyroid carcinomas of children after Chernobyl in contrast to adult thyroid tumours. Br J Cancer 77:952–955[Medline]
  5. Nikiforov YE, Nikiforova MN, Gnepp DR, Fagin JA 1996 Prevalence of mutations of ras and p53 in benign and malignant thyroid tumors from children exposed to radiation after the Chernobyl nuclear accident. Oncogene 13:687–693[Medline]
  6. Santoro M, Thomas GA, Vecchio G, Williams GH, Fusco A, Chiappetta G, Pozcharskaya V, Bogdanova TI, Demidchik EP, Cherstvoy ED, Voscoboinik L, Tronko ND, Carss A, Bunnell H, Tonnachera M, Parma J, Dumont JE, Keller G, Hofler H, Williams ED 2000 Gene rearrangement and Chernobyl related thyroid cancers. Br J Cancer 82:315–322[CrossRef][Medline]
  7. Singer G, Oldt III R, Cohen Y, Wang BG, Sidransky D, Kurman RJ, Shih I 2003 Mutations in BRAF and KRAS characterize the development of low-grade ovarian serous carcinoma. J Natl Cancer Inst 95:484–486[Abstract/Free Full Text]
  8. Naoki K, Chen TH, Richards WG, Sugarbaker DJ, Meyerson M 2002 Missense mutations of the BRAF gene in human lung adenocarcinoma. Cancer Res 62:7001–7003[Abstract/Free Full Text]
  9. Brose MS, Volpe P, Feldman M, Kumar M, Rishi I, Gerrero R, Einhorn E, Herlyn M, Minna J, Nicholson A, Roth JA, Albelda SM, Davies H, Cox C, Brignell G, Stephens P, Futreal PA, Wooster R, Stratton MR, Weber BL 2002 BRAF and RAS mutations in human lung cancer and melanoma. Cancer Res 62:6997–7000[Abstract/Free Full Text]
  10. Rajagopalan H, Bardelli A, Lengauer C, Kinzler KW, Vogelstein B, Velculescu VE 2002 Tumorigenesis: RAF/RAS oncogenes and mismatch-repair status. Nature 418:934[CrossRef][Medline]
  11. Pollock PM, Meltzer PS 2002 A genome-based strategy uncovers frequent BRAF mutations in melanoma. Cancer Cell 2:5–7[CrossRef][Medline]
  12. Davies H, Bignell GR, Cox C, Stephens P, Edkins S, Clegg S, Teague J, Woffendin H, Garnett MJ, Bottomley W, Davis N, Dicks E, Ewing R, Floyd Y, Gray K, Hall S, Hawes R, Hughes J, Kosmidou V, Menzies A, Mould C, Parker A, Stevens C, Watt S, Hooper S, Wilson R, Jayatilake H, Gusterson BA, Cooper C, Shipley J, Hargrave D, Pritchard-Jones K, Maitland N, Chenevix-Trench G, Riggins GJ, Bigner DD, Palmieri G, Cossu A, Flanagan A, Nicholson A, Ho JW, Leung SY, Yuen ST, Weber BL, Seigler HF, Darrow TL, Paterson H, Marais R, Marshall CJ, Wooster R, Stratton MR, Futreal PA 2002 Mutations of the BRAF gene in human cancer. Nature 417:949–954[CrossRef][Medline]
  13. Kimura ET, Nikiforova MN, Zhu Z, Knauf JA, Nikiforov YE, Fagin JA 2003 High prevalence of BRAF mutations in thyroid cancer: genetic evidence for constitutive activation of the RET/PTC-RAS-BRAF signaling pathway in papillary thyroid carcinoma. Cancer Res 63:1454–1457[Abstract/Free Full Text]
  14. Soares P, Trovisco V, Rocha AS, Lima J, Castro P, Preto A, Maximo V, Botelho T, Seruca R, Sobrinho-Simoes M 2003 BRAF mutations and RET/PTC rearrangements are alternative events in the etiopathogenesis of PTC. Oncogene 22:4578–4580[CrossRef][Medline]
  15. Cohen Y, Xing M, Mambo E, Guo Z, Wu G, Trink B, Beller U, Westra WH, Ladenson PW, Sidransky D 2003 BRAF mutation in papillary thyroid carcinoma. J Natl Cancer Inst 95:625–627[Abstract/Free Full Text]
  16. Pollock PM, Harper UL, Hansen KS, Yudt LM, Stark M, Robbins CM, Moses TY, Hostetter G, Wagner U, Kakareka J, Salem G, Pohida T, Heenan P, Duray P, Kallioniemi O, Hayward NK, Trent JM, Meltzer PS 2003 High frequency of BRAF mutations in nevi. Nat Genet 33:19–20[CrossRef][Medline]
  17. Peyssonnaux C, Eychene A 2001 The Raf/MEK/ERK pathway: new concepts of activation. Biol Cell 93:53–62[CrossRef][Medline]
  18. Avruch J, Khokhlatchev A, Kyriakis JM, Luo Z, Tzivion G, Vavvas D, Zhang XF 2001 Ras activation of the Raf kinase: tyrosine kinase recruitment of the MAP kinase cascade. Recent Prog Horm Res 56:127–155[Abstract]
  19. Kolch W 2000 Meaningful relationships: the regulation of the Ras/Raf/MEK/ERK pathway by protein interactions. Biochem J 351:289–305
  20. Kumar R, Angelini S, Hemminki K 2003 Activating BRAF and N-Ras mutations in sporadic primary melanomas: an inverse association with allelic loss on chromosome 9. Oncogene 22:9217–9224[CrossRef][Medline]
  21. Trovisco V, Vieira de Castro I, Soares P, Maximo V, Silva P, Magalhaes J, Abrosimov A, Guiu XM, Sobrinho-Simoes M 2004 BRAF mutations are associated with some histological types of papillary thyroid carcinoma. J Pathol 202:247–251[CrossRef][Medline]
  22. Nikiforova MN, Kimura ET, Gandhi M, Biddinger PW, Knauf JA, Basolo F, Zhu Z, Giannini R, Salvatore G, Fusco A, Santoro M, Fagin JA, Nikiforov YE 2003 BRAF mutations in thyroid tumors are restricted to papillary carcinomas and anaplastic or poorly differentiated carcinomas arising from papillary carcinomas. J Clin Endocrinol Metab 88:5399–5404[Abstract/Free Full Text]
  23. Fukushima T, Suzuki S, Mashiko M, Ohtake T, Endo Y, Takebayashi Y, Sekikawa K, Hagiwara K, Takenoshita S 2003 BRAF mutations in papillary carcinomas of the thyroid. Oncogene 22:6455–6457[CrossRef][Medline]
  24. Namba H, Nakashima M, Hayashi T, Hayashida N, Maeda S, Rogounovitch TI, Ohtsuru A, Saenko VA, Kanematsu T, Yamashita S 2003 Clinical implication of hot spot BRAF mutation, V599E, in papillary thyroid cancers. J Clin Endocrinol Metab 88:4393–4397[Abstract/Free Full Text]
  25. Xu X, Quiros RM, Gattuso P, Ain KB, Prinz RA 2003 High prevalence of BRAF gene mutation in papillary thyroid carcinomas and thyroid tumor cell lines. Cancer Res 63:4561–4567[Abstract/Free Full Text]
  26. Xing M, Vasko V, Tallini G, Larin A, Wu G, Udelsman R, Ringel MD, Ladenson PW, Sidransky D 2004 BRAF T1796A transversion mutation in various thyroid neoplasms. J Clin Endocrinol Metab 89:1365–1368[Abstract/Free Full Text]
  27. Harach HR, Williams ED 1995 Childhood thyroid cancer in England and Wales. Br J Cancer 72:777–783[Medline]
  28. Williams D 2002 Cancer after nuclear fallout: lessons from the Chernobyl accident. Nat Rev Cancer 2:543–549[CrossRef][Medline]
  29. Nikiforov YE 2002 RET/PTC rearrangement in thyroid tumors. Endocr Pathol 13:3–16[CrossRef][Medline]
  30. Williams GH, Rooney S, Thomas GA, Cummins G, Williams ED 1996 RET activation in adult and childhood papillary thyroid carcinoma using a reverse transcriptase-n-polymerase chain reaction approach on archival-nested material. Br J Cancer 74:585–589[Medline]
  31. Dahm-Daphi J, Sass C, Alberti W 2000 Comparison of biological effects of DNA damage induced by ionizing radiation and hydrogen peroxide in CHO cells. Int J Radiat Biol 76:67–75[CrossRef][Medline]



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A Salajegheh, E B Petcu, R A Smith, and A K-Y Lam
Follicular variant of papillary thyroid carcinoma: a diagnostic challenge for clinicians and pathologists
Postgrad. Med. J., February 1, 2008; 84(988): 78 - 82.
[Abstract] [Full Text] [PDF]

Home page
 Endocr Relat CancerHome page
G. Riesco-Eizaguirre and P. Santisteban
New insights in thyroid follicular cell biology and its impact in thyroid cancer therapy
Endocr. Relat. Cancer, December 1, 2007; 14(4): 957 - 977.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
R. Ciampi and Y. E. Nikiforov
RET/PTC Rearrangements and BRAF Mutations in Thyroid Tumorigenesis
Endocrinology, March 1, 2007; 148(3): 936 - 941.
[Abstract] [Full Text] [PDF]

Home page
 Eur J EndocrinolHome page
M. Santoro, R. M. Melillo, and A. Fusco
RET/PTC activation in papillary thyroid carcinoma: European Journal of Endocrinology Prize Lecture.
Eur. J. Endocrinol., November 1, 2006; 155(5): 645 - 653.
[Abstract] [Full Text] [PDF]

Home page
 Endocr Relat CancerHome page
M Niedziela
Pathogenesis, diagnosis and management of thyroid nodules in children.
Endocr. Relat. Cancer, June 1, 2006; 13(2): 427 - 453.
[Abstract] [Full Text] [PDF]

Home page
 Endocr Relat CancerHome page
L Fugazzola, E Puxeddu, N Avenia, C Romei, V Cirello, A Cavaliere, P Faviana, D Mannavola, S Moretti, S Rossi, et al.
Correlation between B-RAFV600E mutation and clinico-pathologic parameters in papillary thyroid carcinoma: data from a multicentric Italian study and review of the literature.
Endocr. Relat. Cancer, June 1, 2006; 13(2): 455 - 464.
[Abstract] [Full Text] [PDF]

Home page
 J. Clin. Endocrinol. Metab.Home page
P. Castro, A. P. Rebocho, R. J. Soares, J. Magalhaes, L. Roque, V. Trovisco, I. Vieira de Castro, M. Cardoso-de-Oliveira, E. Fonseca, P. Soares, et al.
PAX8-PPAR{gamma} Rearrangement Is Frequently Detected in the Follicular Variant of Papillary Thyroid Carcinoma
J. Clin. Endocrinol. Metab., January 1, 2006; 91(1): 213 - 220.
[Abstract] [Full Text] [PDF]

Home page
 Epidemiol RevHome page
M. Hatch, E. Ron, A. Bouville, L. Zablotska, and G. Howe
The Chernobyl Disaster: Cancer following the Accident at the Chernobyl Nuclear Power Plant
Epidemiol. Rev., July 1, 2005; 27(1): 56 - 66.
[Full Text] [PDF]

Home page
 INT J SURG PATHOLHome page
P. Castro, L. Roque, J. Magalhaes, and M. Sobrinho-Simoes
A Subset of the Follicular Variant of Papillary Thyroid Carcinoma Harbors the PAX8-PPAR{gamma} Translocation
International Journal of Surgical Pathology, July 1, 2005; 13(3): 235 - 238.
[Abstract] [PDF]

Home page
 Endocr Relat CancerHome page
M Xing
BRAF mutation in thyroid cancer
Endocr. Relat. Cancer, June 1, 2005; 12(2): 245 - 262.
[Abstract] [Full Text] [PDF]

Home page
 J. Clin. Endocrinol. Metab.Home page
J. A. Fagin
Challenging Dogma in Thyroid Cancer Molecular Genetics--Role of RET/PTC and BRAF in Tumor Initiation
J. Clin. Endocrinol. Metab., September 1, 2004; 89(9): 4264 - 4266.
[Full Text] [PDF]

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