Kinases are downstream modulators and effectors of several cellular signaling cascades and play key roles in the development of neoplastic disease. In this study, we aimed to evaluate SRC, LYN and CKB protein and mRNA expression, as well as their promoter methylation, in gastric cancer. We found elevated expression of SRC and LYN kinase mRNA and protein but decreased levels of CKB kinase, alterations that may have a role in the invasiveness and metastasis of gastric tumors. Expression of the three studied kinases was also associated with MYC oncogene expression, a possible biomarker for gastric cancer. To understand the mechanisms that regulate the expression of these genes, we evaluated the DNA promoter methylation of the three kinases. We found that reduced SRC and LYN methylation and increased CKB methylation was associated with gastric cancer. The reduced SRC and LYN methylation was associated with increased levels of mRNA and protein expression, suggesting that DNA methylation is involved in regulating the expression of these kinases. Conversely, reduced CKB methylation was observed in samples with reduced mRNA and protein expression, suggesting CKB expression was found to be only partly regulated by DNA methylation. Additionally, we found that alterations in the DNA methylation pattern of the three studied kinases were also associated with the gastric cancer onset, advanced gastric cancer, deeper tumor invasion and the presence of metastasis. Therefore, SRC, LYN and CKB expression or DNA methylation could be useful markers for predicting tumor progression and targeting in anti-cancer strategies.

No abstract

Breast cancer in families with germ line mutations in the TP53 gene has been described in the medical literature. Mutation screening for susceptibility genes should allow effective prophylactic and preventive measures. Using single-strand conformational polymorphism, we screened for mutations in exons 5, 6, 7 and 8 of gene TP53 in the peripheral blood of 8 young non-affected members (17 to 36 years old) of families with a history of breast cancer. Studies of this type on young patients (mean age, 25 years) are very rare in the literature. The identification of these mutations would contribute to genetic counseling of members of families with predisposition to breast cancer. The results obtained did not show any polymorphism indicating mutation. In our sample, the familial tumorigenesis is probably related to other gene etiologies.

As lesões benignas da mama geralmente comportam-se como proliferações inócuas e limitadas, mas algumas vezes podem representar patologias pré-cancerosas. A importância prática do estudo das hiperplasias epiteliais (HE) está relacionada com o seu potencial de transformação maligna. O gene supressor de tumor TP53 é o que sofre o maior número de mutações em câncer humano. Usando a técnica do polimorfismo conformacional de fita simples, triamos mutações nos exons 5 ao 8 do gene TP53 em hiperplasias epiteliais da mama. Os resultados obtidos não revelaram qualquer polimorfismo indicativo de mutação. A ausência de mutação é um indicativo de que este gene não está envolvido no processo de iniciação da malignização, reforçando a hipótese de que as mutações no gene TP53 são um evento tardio na carcinogênese mamária.