GUILHERME FRANCISCO
Projetos de Pesquisa
Unidades Organizacionais
LIM/24 - Laboratório de Oncologia Experimental, Hospital das Clínicas, Faculdade de Medicina
3 resultados
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- Arg72Pro TP53 polymorphism and cancer susceptibility: a comprehensive meta-analysis of 302 case-control studies(2011) FRANCISCO, Guilherme; MENEZES, Paulo Rossi; ELUF-NETO, Jose; CHAMMAS, RogerArg72Pro is a common polymorphism in TP53, showing differences in its biological functions. Case-control studies have been performed to elucidate the role of Arg72Pro in cancer, although the results are conflicting and heterogeneous. Here, we analyzed pooled data from case-control studies to determine the role of Arg72Pro in different cancer sites. We performed a systematic review and meta-analysis of 302 case-control studies that analyzed Arg72Pro in cancer susceptibility. Odds ratios were estimated for different tumor sites using distinct genetic models, and the heterogeneity between studies was explored using I(2) values and meta-regression. We adopted quality criteria to classify the studies. Subgroup analyses were done for tumor sites according to ethnicity, histological, and anatomical sites. Results indicated that Arg72Pro is associated with higher susceptibility to cancer in some tumor sites, mainly hepatocarcinoma. For some tumor sites, quality of studies was associated with the size of genetic association, mainly in cervical, head and neck, gastric, and lung cancer. However, study quality did not explain the observed heterogeneity substantially. Meta-regression showed that ethnicity, allelic frequency and genotyping method were responsible for a substantial part of the heterogeneity observed. Our results suggest ethnicity and histological and anatomical sites may modulate the penetrance of Arg72Pro in cancer susceptibility. This meta-analysis denotes the importance for more studies with good quality and that the covariates responsible for heterogeneity should be controlled to obtain a more conclusive response about the function of Arg72Pro in cancer.
- Association between the p27 rs2066827 variant and tumor multiplicity in patients harboring MEN1 germline mutations(2014) LONGUINI, Viviane C.; LOURENCO JR., Delmar M.; SEKIYA, Tomoko; MEIRELLES, Osorio; GONCALVES, Tatiana D.; COUTINHO, Flavia L.; FRANCISCO, Guilherme; OSAKI, Luciana H.; CHAMMAS, Roger; ALVES, Venancio A. F.; SIQUEIRA, Sheila A. C.; SCHLESINGER, David; NASLAVSKY, Michel S.; ZATZ, Mayana; DUARTE, Yeda A. O.; LEBRAO, Maria Lucia; GAMA, Patricia; LEE, Misu; MOLATORE, Sara; PEREIRA, Maria Adelaide A.; JALLAD, Raquel S.; BRONSTEIN, Marcello D.; CUNHA-NETO, Malebranche B.; LIBERMAN, Bernardo; FRAGOSO, Maria Candida B. V.; TOLEDO, Sergio P. A.; PELLEGATA, Natalia S.; TOLEDO, Rodrigo A.Objective: To date, no evidence of robust genotype-phenotype correlation or disease modifiers for multiple endocrine neoplasia type 1 (MEN1) syndrome has been described, leaving the highly variable clinical presentation of patients unaccounted for. Design: As the CDKN1B (p27) gene causes MEN4 syndrome and it is transcriptionally regulated by the product of the MEN1 gene (menin), we sought to analyze whether p27 influences the phenotype of MEN1-mutated patients. The cohort consisted of 100 patients carrying germline MEN1 gene mutations and 855 population-matched control individuals. Methods: Genotyping of the coding p27 c.326T>G (V109G) variant was performed by sequencing and restriction site digestion, and the genotypes were associated with clinical parameters by calculating odds ratios (ORs) and their 95% CIs using logistic regression. Results: There were significant differences in p27 V109G allele frequencies between controls and MEN1-mutated patients (OR=2.55, P=0.019, CI=1.013-5.76). Among patients who are >= 30 years old carrying truncating MEN1 mutations, the T allele was strongly associated with susceptibility to tumors in multiple glands (three to four glands affected vs one to two glands affected; OR=18.33; P=0.002, CI=2.88-16.41). This finding remained significant after the Bonferroni's multiple testing correction, indicating a robust association. No correlations were observed with the development of MEN1-related tumors such as hyperparathyroidism, pituitary adenomas, and enteropancreatic and adrenocortical tumors. Conclusions: Our study suggests that the p27 tumor suppressor gene acts as a disease modifier for the MEN1 syndrome associated with MEN1 germline mutations. If confirmed in independent patient cohorts, this finding could facilitate the management of this clinically complex disease.
- Predominant role of DNA polymerase eta and p53-dependent translesion synthesis in the survival of ultraviolet-irradiated human cells(2017) LERNER, Leticia K.; FRANCISCO, Guilherme; SOLTYS, Daniela T.; ROCHA, Clarissa R. R.; QUINET, Annabel; VESSONI, Alexandre T.; CASTRO, Ligia P.; DAVID, Taynah I. P.; BUSTOS, Silvina O.; STRAUSS, Bryan E.; GOTTIFREDI, Vanesa; STARY, Anne; SARASIN, Alain; CHAMMAS, Roger; MENCK, Carlos F. M.Genome lesions trigger biological responses that help cells manage damaged DNA, improving cell survival. Pol eta is a translesion synthesis (TLS) polymerase that bypasses lesions that block replicative polymerases, avoiding continued stalling of replication forks, which could lead to cell death. p53 also plays an important role in preventing cell death after ultraviolet (UV) light exposure. Intriguingly, we show that p53 does so by favoring translesion DNA synthesis by pol eta. In fact, the p53-dependent induction of pol eta in normal and DNA repair-deficient XP-C human cells afterUV exposure has a protective effect on cell survival after challenging UV exposures, which was absent in p53-and Pol H-silenced cells. Viability increase was associated with improved elongation of nascent DNA, indicating the protective effect was due to more efficient lesion bypass by pol eta. This protection was observed in cells proficient or deficient in nucleotide excision repair, suggesting that, from a cell survival perspective, proper bypass of DNA damage can be as relevant as removal. These results indicate p53 controls the induction of pol eta in DNA damaged human cells, resulting in improved TLS and enhancing cell tolerance to DNA damage, which parallels SOS responses in bacteria.