Presence of BRCA1 Gene Mutation in Bitches with Malignant Mammary Tumors

Camila Calvi Menegassi Ferreira, Stefhano Luis Cândido, Luciana Maria Curtio Soares, Matias Bassinello Stocco, Andresa de Cássia Martini, Lianna Ghisi Gomes, Luciano Nakazato, Roberto Lopes de Souza


BackgroundMammary tumors (MTs) in bitches are similar to breast cancers in women. Thus, they can be used as a model for human breast cancer and findings can be extrapolated for use in human medicine. BRCA1 is a tumor suppressor gene. When the gene has a mutation, it cannot repair damaged DNA, which causes genetic instability and tumorigenesis. Therefore, we aimed to study the frequency of single nucleotide polymorphisms (SNPs) in the BRCA1 gene that are associated with distinct histological types of malignant MT in bitches.

Materials, Methods & Results: The study population consisted of 91 bitches, including a control group of 6 animals with healthy mammary glands and 85 animals with MTs. All animals underwent a presurgery evaluation consisting of a questionnaire administered to the person responsible for the animal, a physical examination, collection of peripheral blood for hematological and serum biochemistry evaluations, an electrocardiogram, and a preanesthesia evaluation. In addition, distant metastasis was studied via chest radiography and abdominal ultrasound. After evaluations were complete, the animals that could undergo surgery were administered general anesthesia and underwent a mastectomy or mammary gland sample collection. Histopathological examination and molecular analysis were performed to identify mutations in the BRCA1 gene. Histopathological examinations found 10 different types of malignant tumors in 36 sick animals. Tumor samples plus samples from the 6 control animals were subjected to DNA extraction, polymerase chain reaction (PCR) analysis, and genetic sequencing. The tumor with the highest incidence (33.33%) was a complex carcinoma, followed by carcinoma in mixed tumor (13.88), tubular carcinoma (13.88) and carcinosarcoma (13.88). Molecular analysis revealed 3 different SNP points in 5 samples (4006G>A, 3619A>G, and 3761C>T). The allelic variant 4006G>A (1/36) resulted in the alteration of the amino acid valine by isoleucine (V1336 I). The mutation 3619A>G (2/36) inserted the amino acid alanine instead of threonine (T1207 A). The mutation 3761C>T (2/36) led to the alteration of the amino acid serine by phenylalanine (S1254 F), a mutation for which there are no published reports. The histological types that showed BRCA1mutations were complex carcinoma (1/5), carcinoma in mixed tumor (1/5), papillary carcinoma (1/5) and tubular carcinoma (2/5). Software analysis identified the new SNP (nucleotide 3761) in BRCA1 and 2 points mutations in nucleotides 4006 and 3619 and responsible for genetic instability.

Discussion: The development of breast cancer is caused by many endogenous and exogenous factors. The results of our study show that these factors have a greater presence in female, mixed breed, uncastrated, and older dogs, confirming the data in the veterinary literature. In the present study, we found different histological types of malignant breast tumors with mutations in the BRCA1 gene, as other authors have reported. However, we also found the mutation 3761C>T, which, to the best of our knowledge, has not been reported in the literature. This shows the need for studies in veterinary medicine that assess mutations in the BRCA1 gene and the most common histological types. In conclusion, SNPs in the BRCA1 gene cause genetic instability, resulting in additional mutations that lead to the development of breast tumors. They are point mutations that affect transcription, resulting in truncated proteins. These proteins may have a loss of function, leading to carcinogenesis.

Keywords: polymorphism, BRCA1 gene, cancer, dogs.

Descritores:polimorfismo, gene BRCA1, câncer, cães.

 Título: Presença da mutação do gene BRCA1 em cadelas com tumores mamários malignos.


Full Text:



Borge K.S., Borresen-Dale A.L. & Lingaas F. 2011. Identification of genetic variation in 11 candidate genes of canine mammary tumour. Veterinary and Comparative Oncology. 9(4): 241-250. DOI: 10.1111/j.1476-5829.2010.00250.x.

Enginler S.O., Akis I., Toydemir T.S.F., Oztabak K., Haktanir D., Gündüz M.C., Kırşan I. & Fırat I. 2014. Genetic variations of BRCA1 and BRCA2 genes in dogs with mammary tumours. Veterinary Research Communications. 38(1): 21-27. DOI: 10.1007/s11259-013-9577-7.

Fossum T.W. 2008. Cirurgia de Pequenos Animais. 3.ed. Rio de Janeiro: Elsevier, pp.702-774.

Gomes M.C.B., Costa M.M., Vieira R., Gomes-Filho F.A., Koifman S., Koifman R.J., Sun P. & Narod S.A. 2011. Prevalência da mutação BRCA1 e BRCA2 em pacientes com câncer de mama em uma população do Rio de Janeiro, Brasil. Revista Brasileira de Oncologia Clínica. 8(27): 24-28.

Im K.S., Kim I.H., Kim N.H., Lim H.Y., Kim J.H. & Sur J.H. 2013. Breed-related differences in altered BRCA1 expression, phenotype and subtype in malignant canine mammary tumors. The Veterinary Journal. 195(3): 366-372. DOI: 10.1016/j.tvjl.2012.07.014.

Kim J.H., Yu C.H., Yhee J.Y., Im K.S. & Sur J.H. 2010. Lymphocyte infiltration, expression of interleukin IL-1, IL-6 and expression of mutated breast cancer susceptibility gene-1 correlate with malignancy of canine mammary tumours. Journal of Comparative Pathology. 142(2-3): 177-186. DOI: 10.1016/j.jcpa.2009.10.023.

Klopfleisch R. & Gruber A.D. 2009. Increased expression of BRCA2 and RAD51 in lymph node metastases of canine mammary adenocarcinomas. Veterinary Pathology. 46(3): 416-422. DOI: 10.1354/vp.08-VP-0212-K-FL.

Lana S.E, Rutteman G.R. & Withrow S.J. 2007. Tumors of the mammary gland. In: Withrow S.J. & Vail D.M. (Eds). Withrow & MacEwen's Small Animal Clinical Oncology. 4th edn. St. Louis: Saunders, pp.619-636.

Lee C.H., Kim W.H., Lim J.H., Kang M.S., Kim D.Y. & Kweon O.K. 2004. Mutation and overexpression of p53 as prognostic factor in canine mammary tumors. Journal of Veterinary Science. 5(1): 63-69.

Marafon C.M. 2007. Genética do câncer de mama hereditário. Revista de Ciências Médicas e Biológicas. 6(1): 86-90.

Melin M., Rivera P., Arendt M., Elvers I., Murén E., Gustafson U., Starkey M., Borge K.S., Lingaas F., Häggström J., Saellström S., Rönnberg H. & Lindblad-Toh K. 2016. Genome-wide Analysis Identifies Germ-line risk factors associated with canine mammary tumours. PLoS Genetics. 12(5): e1006029. DOI: 10.1371/journal.pgen.1006029.

Misdorp W. 2002. Tumors of the mammary gland. In: Meuten D.J. (Ed). Tumors in Domestic Animals. 4th edn. Ames: Iowa State Press. pp.575-606.

Nieto A., Péres-Alenza M.D., Del-Castillo N., Tabanera E., Castaño M. & Peña L. 2003. BRCA1 expression in canine mammary dysplasias and tumours: Relationship with prognostic variables. Journal of Comparative Pathology. 128(4): 260-268. DOI: 10.1053/jcpa.2002.0631.

Oliveira J.C.F., Kommers G.D., Masuda E.K., Marques B.M.F.P.P., Fighera R.A., Irigoyen L.F. & Barros C.S.L. 2010. Estudo retrospectivo de 1.647 tumores mamários em cães. Pesquisa Veterinária Brasileira. 30(2): 177-185. DOI: 10.1590/S0100-736X2010000200014.

Qiu H. & Lin D. 2016. Roles of DNA mutation in the coding region and DNA methylation in the 5’ flanking region of BRCA1 in canine mammary tumors. The Journal of Veterinary Medical Science. 78(6): 943-949. DOI: 10.1292/jvms.15-0557.

Ribas C.R., Dornbusch P.T., Faria M.R., Wouk A.F.P.F. & Ciro S.M. 2012. Alterações Clínicas relevantes em cadelas com neoplasias mamárias estiadas. Archives of Veterinary Science. 17(1): 60-68.

Rieger P.T. 2004. The biology of cancer genetics. Seminars in Oncology Nursing. 20(3): 145-154. DOI: 10.1053/j.soncn.2004.04.001.

Rivera P., Melin M., Biagi T., Fall T., Häggström J., Lindblad-Toh K. & Von-Euler H. 2009. Mammary tumor development in Dogs is associated with BRCA1 and BRCA2. Molecular Biology, Pathobiology and Genetics. 69(22): 8770-8774. DOI: 10.1158/0008-5472.

Rivera P. & Von-Euler H. 2011. Molecular biological aspects on canine and human mammary tumors. Veterinary Pathology. 48(1): 132-146. DOI: 10.1177/0300985810387939.

Rutteman G.R., Withrow S.J. & MacEwen E.G. 2001. Tumors of the mammary gland. In: Withrow S.J. & MacEwen E.G. (Eds). Small Animal Clinical Oncology. 3rd edn. Philadelphia: Saunders, pp.455-477.

Sambrook J. & Russell D.W. 2001. Molecular cloning: a laboratory manual. 3rd edn. New York: Cold Spring Harbor Laboratory Press, pp.8.18-8.113.

Silva A.R., Garcia S.B., Chahud F. & Zucoloto S. 2005. Impacto prognóstico da expressão imuno-histoquímica do BRCA1 nos carcinomas mamários esporádicos. Jornal Brasileiro de Patologia e Medicina Laboratorial. 41(3): 197-203. DOI: 10.1590/S1676-24442005000300010.

Thuróczy J., Reisvaag G.J.K., Perge E., Tibold A., Szilágyi J. & Balogh L. 2007. Immunohistochemical detection of progesterone and cellular proliferation in canine mammary tumours. Journal of Comparative Pathology. 137(2-3): 122-129. DOI: 10.1016/j.jcpa.2007.05.005.

Tsuchida S., Ikemoto S. & Tagawa M. 2001. Microsatellite Polymorphism in Intron 14 of the Canine BRCA1 Gene. Journal of Veterinary Medical Science. 63(4): 479-481. DOI: 10.1292/jvms.63.479.

Vascellari M., Capello K., Carminato A., Zanardello C., Baioni E. & Mutinelli F. 2016. Incidence of mammary tumors in the canine population living in the Veneto region (Northeastern Italy): Risk factors and similarities to human breast cancer. Preventive Veterinary Medicine. 1(126): 183-189. DOI: 10.1016/j.prevetmed.2016.02.008.

Walsh E.M., Farrell M.P., Nolan C., Gallagher F., Clarke R., McCaffrey J.A., Kennedy M.J., Barry M., Kell M.R. & Gallagher D.J. 2016. Breast cancer detection among Irish BRCA1 & BRCA2 mutation carriers: a population-based study. Irish Journal of Medical Science. 185(1): 189-194. DOI: 10.1007/s11845-015-1267-8.


Copyright (c) 2021 Camila Calvi Menegassi Ferreira, Stéfhano Luis Cândido, Luciana Maria Curtio Soares, Matias Bassinello Stocco, Andresa de Cássia Martini, Lianna Ghisi Gomes, Luciano Nakazato, Roberto Lopes de Souza

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.