Identification of Germline Mutations in Genes Involved in Classic FAP in Patients from Northern Brazil.

BACKGROUND: Colorectal cancer is a common cancer worldwide, with 5-10% of cases being hereditary. Familial adenomatous polyposis syndrome (FAP) is caused by germline mutations in the APC gene or rarely in the MUTYH gene. PATIENTS AND METHODS: This work did not identify germline mutations in the MUTYH, NTHL1, POLD1 and POLE genes in 15 individuals belonging to five families with classic FAP, who had the mutation in the APC gene confirmed in a previous study. Our results support mutations in the APC gene as the main genetic contribution of classical FAP with severe phenotype. In the family that had the most aggressive form of the disease, we performed an array-based Comparative Genomic Hybridization analysis and identified the germinal loss of an allele of the NOTCH2 and BMPR2 genes in the mother (proband) and daughter. In order to validate the involvement of these genes in the other four families of this study, we analyzed the DNA copy number variation in the peripheral blood of the 15 participants. RESULTS: FAP is a syndrome with considerable genetic and phenotypic heterogeneity and this phenomenon may explain the presence of secondary genetic alterations, such as the allelic loss of NOTCH2 and BMPR2 genes, found only in one family in this study. The CNV analysis confirmed that only the two members of the FAP2 family (patient 02H and 02F) had a deletion of these two genes, as the aCGH methodology had found. The other study participants did not show allelic loss for these two genes. CONCLUSION: Validation in a larger number of families could confirm the presence of these new genetic alterations in classic FAP and improve understanding of the different types of aggressiveness of the disease.

Significance of P16INK4A Expression and PTEN Loss of Heterozygosity in Human Papilloma Virus-related Oral Squamous Cell Carcinoma.

BACKGROUND/AIM: p16 and PTEN are tumor suppressor genes. Loss of these molecules in oral squamous cell carcinoma (OSCC) has been studied worldwide. In this study, we explored whether p16 cooperates with inactive PTEN during the pathogenesis of OSCC, especially in regard to tumor aggressiveness and proliferation. MATERIALS AND METHODS: Immunocytochemistry and western blot analysis were used to examine the levels of p16 and PTEN. Sequencing analysis was performed to identify mutations in the PTEN gene and HPV infection. Fluorescence in situ hybridization was used to examine the presence of the PTEN locus. RESULTS: PTEN analysis showed high positivity in T4 samples. HPV-positive tumors correlated with tabagism, tumor size 3 and 4, disease stages 3 and 4, presence of lymph node metastasis (N1) and poor differentiation. Immunoexpression of p16 was strongly correlated with the presence of HPV. CONCLUSION: PTEN demonstrated a higher reactivity in advanced disease stages and p16 was strongly associated with HPV. Viral presence decreases tumor aggressiveness. Patients with advanced stage lesions demonstrated lower survival rate.

Deregulation of the SRC Family Tyrosine Kinases in Gastric Carcinogenesis in Non-human Primates.

BACKGROUND/AIM: The evolution of gastric carcinogenesis remains largely unknown, as the regulatory mechanisms involved in the aggressiveness of gastric cancer are still poorly understood. Kinases are downstream modulators and effectors of various cell signaling cascades and play key roles in the development of neoplastic diseases. The objective of this study was to evaluate the expression of genes and proteins of the SRC family, including FYN, YES, BLK, FGR, LYN and SRC, in a model of intestinal gastric carcinogenesis generated by treating Cebus apella, a New World non-human primate, with N-methyl nitrosourea (MNU). MATERIALS AND METHODS: mRNA expression of genes was measured by real-time reverse transcription quantitative PCR (RT-qPCR) and protein expression was measured by western blotting in six Cebus apella treated with N-methyl-nitrosourea (MNU) for about 2.5 years. RESULTS: Elevated mRNA and protein expression mainly of the SRC and LYN kinases was observed. Their expression was gradually increasing as non-atrophic gastritis was evolving to gastric cancer. CONCLUSION: SRC family kinases play a key role in tumor progression and metastasis and may be a promising target for the treatment of gastric cancer.

Molecular biology as a tool for the treatment of cancer.

Cancer is a genetic disease characterized by uncontrolled cell growth and metastasis. Cancer can have a number of causes, such the activation of oncogenes, the inactivation of tumor-suppressing genes, mutagenesis provoked by external factors, and epigenetic modifications. The development of diagnostic tools and treatments using a molecular biological approach permits the use of sensitive, low-cost, noninvasive tests for cancer patients. Biomarkers can be used to provide rapid, personalized oncology, in particular the molecular diagnosis of chronic myeloid leukemia, and gastric, colon, and breast cancers. Molecular tests based on DNA methylation can also be used to direct treatments or evaluate the toxic effects of chemotherapy. The adequate diagnosis, prognosis, and prediction of the response of cancer patients to treatment are essential to ensure the most effective therapy, reduce the damaging effects of treatment, and direct the therapy to specific targets, and in this context, molecular biology has become increasingly important in oncology. In this brief review, we will demonstrate the fundamental importance of molecular biology for the treatment of three types of cancer-chronic myeloid leukemia, hereditary diffuse gastric cancer, and astrocytomas (sporadic tumors of the central nervous system). In each of these three models, distinct biological mechanisms are involved in the transformation of the cells, but in all cases, molecular biology is fundamental to the development of personalized analyses for each patient and each type of neoplasia, and to guarantee the success of the treatment.

Frequency of the Loss of Heterozygosity of the NF2 Gene in Sporadic Spinal Schwannomas.

BACKGROUND/AIM: Individuals with type 2 Neurofibromatosis are predisposed for the appearance of schwannomas. In the present study we analyzed the loss of heterozygosity and mutations in the NF2 gene in patients with sporadic Schwannoma without Neurofibromatosis type 2. MATERIALS AND METHODS: We analyzed 39 patients with sporadic spinal schwannoma. We quantified the number of alleles by FISH and sequenced the NF2 gene. RESULTS: We identified 16/39 patients with point mutations and/or LOHs in the tumor samples analyzed. The LOHs were found in 7/39 patients. Two homozygous mutations were detected in 4/39 tumors, and the presence of the mutation in heterozygosis was revealed in 3/39 patients. In two tumors, we detected the loss of one allele of the NF2 gene, with no mutation. CONCLUSION: The genetic alterations observed in the NF2 gene indicated that spinal schwannomas are associated with genetic alterations also found in other schwannomas and type 2 Neurofibromatosis, which reinforces the etiological role of this gene.

Prevalence of occult hepatitis B in a population from the Brazilian Amazon region.

In the present study, we evaluated the prevalence of occult hepatitis B (OBI) in a population from the Brazilian Amazon region, identify circulating genotypes, and mutations in the S gene. One hundred eighty-one patients with negative serology for HBsAg and anti-HBs and positive serology for anti-HBc participated in the study. Detection of viral DNA, genotyping by sequencing, and analysis of nucleotide sequences to detect possible mutations were performed. HBV DNA was detected in 14.36% of the patients. Genotyping revealed genotype A in 88.46% of HBV DNA-positive subjects, with subgenotype A1 being the most prevalent (78.26%) followed by subgenotype A2 (21.74%). Genotype F was detected in 11.54% (all of them subgenotype F2). Amino acid substitutions were observed in the amplified S gene in individuals with OBI compared to HBsAg-positive individuals (evident infection). In conclusion, the results show a high prevalence of OBI in the population studied, with a pattern of genotypes A and F that circulate in the Brazilian Amazon region. Amino acid substitutions were detected in part of the S gene in patients with OBI. Further studies on the molecular epidemiology of HBV in this region are important to identify patients considered healthy but who are potential transmitters of the disease.