58º Congresso Brasileiro de Genética
Resumos do 58o Congresso Brasileiro de Genética • 11 a 14 de setembro de 2012
Rafain Palace Hotel e Convention Center • Foz do Iguaçu • PR • Brasil
www.sbg.org.br - ISBN 978-85-89109-06-2
84
Evaluation of the benefits of the treatment
with melatonin in canine mammary tumors
estrogen-dependent or no
Lopes, JR1,2; Maschio, LB2; Jardim, BV1,2; Ferreira, LC1,2; Borin, TF2; Moschetta, MG2; Gonçalves, NN2; Leonel, C1,2;
Gelaleti, GB1,2; Zuccari, DAPC1,2
1
Graduate Program in Genetics, Universidade Estadual Paulista - UNESP/IBILCE, São José do Rio Preto, SP, Brazil;
2
Laboratory of Cancer Molecular Investigation (LCMI), Departament of Molecular Biology - Faculdade de Medicina de
São José do Rio Preto, FAMERP, São José do Rio Preto, SP, Brazil.
[email protected]
Keywords: Immunohistochemistry, Cell culture, Cancer agent, Breast cancer, Estrogen receptor.
Mammary cancer is the most common tumor in female dogs, accounting for approximately 52% of all tumors in
this animal population. The identification of new molecules that can be use as alternative treatment for this tumor
type has proven to be potentially useful. The administration of melatonin, a hormone secreted by the pineal gland,
can have oncostatic effects in several types of cancer. Regarding breast cancer, its importance is significant and the
probable mechanism of action is its interaction with estrogenic receptors in epithelial cells. From this interaction,
melatonin would be able to inhibit the proliferation of neoplastic cells in vitro, especially in estrogen-dependent
breast tumors. Thus, the aim of this study was to evaluate the immunohistochemical expression of estrogen
receptor in tumor tissue of female dogs in order to compare them with the cellular response to melatonin. Tumor
fragments of two female dogs were collected and divided in two: the first was placed in formaldehyde to perform
the immunohistochemical procedure for estrogen receptor (ER) and the second was placed in transport medium to
perform the cell culture and the treatment with melatonin. The mammary cancer fragments were cultured in medium
DMEM (E) and incubated at 37°C in 5% CO2. It was established two groups: Control group (untreated) and Group
treated with different concentrations of melatonin (0,5mM, 1mM, 2mM, 5mM and 10mM). Cell viability was
verified by MTT assay. The results were analyzed evaluating the mean and standard error. The expression of estrogen
receptor (ER) was detected by Immunohistochemistry using anti-ER primary antibody (Santa Cruz ®), 1: 150 and
were considered positive when more than 10% of tumor cells showed nuclear and cytoplasmatic staining. It was
found that the ER- negative tumor is more resistant, because it was required a higher dose of melatonin (10mM)
to reduce in 40% the cell viability. For tumor ER- positive the 1mM of melatonin was the most effective. Our
results suggest that melatonin decreases the viability of neoplastic cells, being more effective for tumors ER-positive,
what opens a new pathway for its use as a therapeutic agent in cancer treatment, in agreement with the literature.
Financial Support: CNPq and FAPESP.