Tiago Collares

Publications (35) View all

• Article: Ewing Sarcoma: influence of TP53 Arg72Pro and MDM2 T309G SNPs.

  Helena S Thurow, Fernando P Hartwig, Clarice S Alho, Deborah S B S Silva, Rafael Roesler, Ana Lucia Abujamra, Caroline Brunetto de Farias, Algemir Lunardi Brunetto, Bernardo L Horta, Odir A Dellagostin, Tiago Collares, Fabiana K Seixas
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  ABSTRACT: The Ewing Sarcoma is an important tumor of bone and soft tissue. The SNPs Arg72Pro of TP53 and T309G of MDM2 have been associated with many cancer types and have been differently distributed among populations worldwide. Based on a case-control design, this study aimed to assess the role of these SNPs in 24 Ewing Sarcoma patients, compared to 91 control individuals. DNA samples were extracted from blood and genotyped for both SNPs by PCR-RFLP and confirmed by DNA sequencing. The results showed an association between the G allele of the T309G and Ewing Sarcoma (P = 0.02). Comparing to the TT carriers, the risk of G allele carriers was 3.35 (95 % CI = 1.22-9.21) with P = 0.02. At the genotypic level, an association of the TT genotype with the control group (P = 0.03) was found. Comparing to the TT genotype, the risk of TG and GG was 2.97 (95 % CI = 1.03-8.58) with P = 0.04 and 5.00 (95 % CI = 1.23-20.34) with P = 0.02, respectively. No associations regarding the Arg72Pro SNP were found. Considering that the T309G has been associated with several types of cancer, including sarcomas, our results indicate that this SNP may also be important to Ewing Sarcoma predisposition.
  Molecular Biology Reports 05/2013; · 2.93 Impact Factor
• Source

  Available from: Fernando Hartwig

  Article: Telomere dysfunction and tumor suppression responses in dyskeratosis congenita: balancing cancer and tissue renewal impairment.

  Fernando Pires Hartwig, Tiago Collares
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  ABSTRACT: Dyskeratosis congenita (DC) encompasses a large spectrum of diseases and clinical manifestations generally related to premature aging, including bone marrow failure and cancer predisposition. The major risk factor for DC is to carry germline telomere-related mutations-in telomerase or telomere shelterin genes-which results in premature telomere dysfunction, thus increasing the risk of premature aging impairments. Despite the advances that have been accomplished in DC research, the molecular aspects underlying the phenotypic variability of the disease remain poorly understood. Here different aspects of telomere biology, concerning adult stem cells senescence, tumor suppression and cancer are considered in the context of DC, resulting in two translational models: late onset of DC symptoms in telomere-related mutations carriers is a potential indicator of increased cancer risk and differences in tumor suppression capacities among the genetic subgroups are (at least partial) causes of different clinical manifestations of the disease. The limitations of both models are presented, and further experiments for their validation, as well as clinical implications, are discussed.
  Ageing research reviews 03/2013; · 5.62 Impact Factor
• Article: Binding pattern and toxicological effects of lectins from genus Canavalia on bovine sperm.

  Cristian Kaefer, Eliza R Komninou, Vinicius F Campos, Priscila M de Leon, Francisco Vassiliepe S Arruda, Kyria S Nascimento, Edson H Teixeira, Francielli M Stefanello, Alethéa G Barschak, João Carlos Deschamps, Fabiana K Seixas, Benildo S Cavada, Tiago Collares
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  ABSTRACT: The aim of this study was to determine the binding patterns of Canavalia ensiformis (ConA), Canavalia boliviana (ConBol) and Canavalia brasiliensis (ConBr) lectins to bovine sperm and their effects on sperm motility, viability, lipid peroxidation, reactive oxygen species production and fertilization ability. ConA bound to whole spermatozoa, with the exception of the equatorial segment, ConBol did not interact with the acrosome region and ConBr exhibited a fragmented binding pattern. The three lectins decreased sperm motility but did not affect cell viability or lipid peroxidation. Nevertheless, ROS production was increased in comparison to controls and a reduction in the cleavage and blastocyst ratio was induced in comparison to controls. In conclusion, this study determined that structurally similar lectins interact differently with bovine sperm and affect sperm motility, viability, lipid peroxidation, ROS production and fertilization ability in various ways.
  Reproductive Toxicology 03/2013; · 3.23 Impact Factor
• Article: Chemical Characterization, Antioxidant and Cytotoxic Activities of Brazilian Red Propolis.

  Caroline Olivieri da Silva Frozza, Charlene Silvestrin Celi Garcia, Gabriela Gambato, Marcia Denize Oliveira de Souza, Mirian Salvador, Sidnei Moura, Francine Ferreira Padilha, Fabiana Kömmling Seixas, Tiago Collares, Sibele Borsuk, Odir Antonio Dellagostin, João Antonio Pêgas Henriques, Mariana Roesch-Ely
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  ABSTRACT: Propolis is known for a long time for its health benefits and biological activities. Here, the red variety from the northeast of Brazil was chemically analyzed and extracts were investigated regarding their antioxidant and antitumor activity. Hydroalcoholic extracts, obtained from the red propolis, revealed polyphenol content, 2,2-diphenyl-1-picrylhydrazyl scavenging potential and enzymatic activities for Catalase-like and Superoxide dismutase-like. Cytotoxic activity was evaluated for human laryngeal epidermoid carcinoma cell (Hep-2), human cervical adenocarcinoma (HeLa) and human normal epithelial embryonic kidney (Hek-293). Survival analysis for non-tumor cell line showed greater IC50 compared to tumor cell lines, suggesting an increased sensitivity that may correlate with the higher proliferative index of the tumor vs. normal cells. Our results indicate that the Brazilian red propolis is capable of inhibiting cancer cell growth and constitutes an excellent source of antioxidant and antitumor natural agent.
  Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association 11/2012; · 2.99 Impact Factor
• Article: Erythropoietin non-viral gene therapy does not affect motility, viability, morphology or concentration of rabbit sperm.

  T F Collares, V F Campos, G Urtiaga, P M M Leon, M G Amaral, C P Hartleben, A J McBride, O A Dellagostin, J C Deschamps, F K Seixas, T Collares
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  ABSTRACT: Erythropoietin (EPO) gene therapy can be used for several purposes; however, its effects on reproductive performance are unknown. The aim of this study was to evaluate the toxicological effects of non-viral (EPO) gene transfer on sperm motility, viability, morphology and concentration. Rabbit EPO cDNA was cloned into a pTarget mammalian expression vector. Rabbits were administered with: (1) pTarget/EPO vector, (2) recombinant human EPO (rHuEpo) and (3) saline (control). Both pTarget/EPO and rHuEpo significantly increased (P < 0.05) hematocrit levels 1 week after injection and they remained significantly higher than the control for up to 5 weeks (P < 0.05), showing that both EPO treatments were effective in stimulating the production of red blood cells in rabbits. The EPO gene transfer or rHuEPO administration had no significant effect (P > 0.05) on sperm motility, vigor, viability, concentration or morphology in the testis.
  animal 11/2012; · 1.74 Impact Factor