Aledson Vitor Felipe

DNA methylation as an epigenetic biomarker in colorectal cancer.

Sporadic colorectal cancer (CRC) is a consequence of the accumulation of genetic and epigenetic alterations that result in the transformation of normal colonic epithelial cells to adenocarcinomas. Studies have indicated that a common event in the tumorigenesis of CRC is the association of global hypomethylation with discrete hypermethylation at the promoter regions of specific genes that are involved in cell cycle regulation, DNA repair, apoptosis, angiogenesis, adhesion and invasion. The present study aimed to investigate the epigenetic changes (DNA methylation) in 24 candidate genes in CRC. A total of 10 candidate hypermethylated (HM) and unmethylated (UM) genes were identified that may be useful epigenetic markers for non-invasive CRC screening. The five genes that had the highest average UM percentages in the control group were MLH1 (71.7%), DKK2 (69.6%), CDKN2A (68.4%), APC (67.5%) and hsa-mir-342 (67.4%). RUNX3 (58.9%), PCDH10 (55.5%), SFRP5 (52.1%), IGF2 (50.4%) and Hnf1b (50.0%) were the five genes with the highest average HM percentages in the test group. In summary, the present preliminary study identified the methylation profiles of normal and cancerous colonic epithelial tissues, and provided the groundwork for future large-scale methylation studies.

N-Acetyltransferase 2 genetic polymorphisms and risk of colorectal cancer

AIM To investigate the possible association between meat intake, cigarette smoking and N-acetyltransferase 2 (NAT2) genetic polymorphisms on colorectal cancer (CRC) risk. METHODS Patients with CRC were matched for gender and age to healthy controls. Meat intake and cigarette smoking were assessed using a specific frequency questionnaire. DNA was extracted from peripheral blood and the genotypes of the polymorphism were assessed by polymerase chain reaction-restriction fragment length polymorphism. Five NAT2 alleles were studied (WT, M1, M2, M3 and M4) using specific digestion enzymes. RESULTS A total of 147 patients with colorectal cancer (76 women and 90 men with colon cancer) and 212 controls were studied. The mean age of the two groups was 62 years. More than half the subjects (59.8% in the case group and 51.9% in the control group) were NAT2 slow acetylators. The odds ratio for colorectal cancer was 1.38 (95% CI: 0.90-2.12) in slow acetylators. Although the number of women was small (n = 76 in the case group), the cancer risk was found to be lower in intermediate (W/Mx) acetylators [odds ratio (OR): 0.55, 95% confidence interval (95% CI): 0.29-1.02]. This difference was not observed in men (OR: 0.56, 95% CI: 0.16-2.00). Among NAT2 fast acetylators (W/W or W/Mx), meat consumption more than 3 times a week increased the risk of colorectal cancer (OR: 2.05, 95% CI: 1.01-4.16). In contrast, cigarette smoking increased the risk of CRC among slow acetylators (OR: 1.97, 95% CI: 1.02-3.79). CONCLUSION The risk of CRC was higher among fast acetylators who reported a higher meat intake. Slow NAT2 acetylation was associated with an increased risk of CRC.

lnterleukin-8 gene polymorphism and susceptibility to gastric cancer in a Brazilian population.

BACKGROUND Studies have demonstrated that some polymorphisms in different interleukin genes may increase the risk of cancer. The aim of this study was to investigate the association between the IL-8 (rs4073) -251A/T gene polymorphism and the risk of gastric cancer (GC). PATIENTS AND METHODS A case-control study was conducted on patients with noncardia gastric cancer. DNA was extracted from leukocytes and the IL-8 (rs4073) -251A/T polymorphism was analyzed by PCR-RFLP. Infection with Helicobacter pylori was investigated in the serum by ELISA. RESULTS The sample consisted of 104 patients with GC and 196 controls. Cigarette smoking (P=0.007) and high fat intake (P=0.01) were more frequent in patients with GC. The proportion of patients infected with H. pylori was similar in the two groups (P=0.101). The frequency of the genotype A/T was higher in the cancer group (P=0.008). An increased risk of GC was found in subjects carrying the genotype A/T (OR=2.50, CI: 1.27-4.90), subjects with high fat intake (OR=1.92, CI: 1.17-3.15), and smokers (OR=2.00, CI: 1.203.31). CONCLUSIONS Subjects with the heterozygous A/T genotype, high fat intake and smokers or ex-smokers presented an increased risk of GC. Individuals with A/A genotype may have protective effect for GC.

RNA interference: a promising therapy for gastric cancer.

Gastric cancer (GC) remains a virtually incurable disease when metastatic and requires early screening tools for detection of early tumor stages. Therefore, finding effective strategies for prevention or recurrence of GC has become a major overall initiative. RNA-interference (RNAi) is an innovative technique that can significantly regulate the expression of oncogenes involved in gastric carcinogenesis, thus constituting a promising epigenetic approach to GC therapy. This review presents recent advances concerning the promising biomolecular mechanism of RNAi for GC treatment.

Genetic polymorphisms of vitamin D receptor (VDR), CYP27B1 and CYP24A1 genes and the risk of colorectal cancer.

Introduction Vitamin D receptor (VDR) and proteins encoded by the genes CYP27B2 and CYP24A1 involved in the production and inactivation of vitamin D can influence vitamin D and the susceptibility to colorectal cancer (CRC). The objective of this study was to investigate the relationship between the risk of CRC and polymorphisms in VDR, CYP27B1 and CYP24A1, lifestyle and dietary habits. Methods The study included 152 patients with CRC and 321 controls. All participants answered a questionnaire on their dietary habits, alcohol consumption and smoking habits. DNA was extracted from peripheral blood. Polymorphisms of BsmI and ApaI were identified by performing PCR-RFLP. Identification of CYP24A1 (rs6013897, rs158552 and rs17217119) and CYP27B1 (rs10877012) polymorphisms was performed by gene sequencing. Results Smoking, alcohol use, and low or no consumption of fruit, cereals and dairy products were associated with an increased risk of CRC. A heterozygous genotype Aa or an association genotype aa + Aa of the VDR ApaI polymorphism increased the risk of CRC. The VDR BsmI polymorphism was not significantly associated with the risk of CRC. Multivariate analysis showed that heterozygous and association genotype AT + AA of the rs6013897 polymorphism, genotype CT of the rs158552 polymorphism, association genotype CT + CC and genotypes AA and GG of the rs17217119 polymorphism of CYP24A1, and heterozygous genotype GT and association genotype GT + TT of the rs10877012 polymorphism in CYP27B1 were associated with a higher risk of CRC. Conclusions Dietary habits, lifestyle, and polymorphisms in VDR (ApaI), CYP24A1 (rs6013897, rs158552, rs17217119) and CYP27B1 (rs10877012) were associated with a higher risk of CRC.

Association between ABCB1 Immunohistochemical Expression and Overall Survival in Gastric Cancer Patients

Gastric cancer (GC) is one of the most common malignancies worldwide. The ABCB1 protein, a member of the ATP-binding cassette (ABC) transporter family, encoded by the ABCB1 gene, considerably influences the distribution of drugs across cell membranes as well as multidrug resistance (MDR) of antineoplastic drugs. In contrast to the extensive knowledge on the pharmacological action of ABCB1 protein, the correlation between the clinical-pathological data and ABCB1 protein expression in patients with GC remains unclear. The aim was to investigate association between ABCB1 expression and overall survival in GC patients. Human tumor fragments from 57 GC patients were examined by immunohistochemistry assay. We observed lower survival rate of patients with GC who were positive for ABCB1 expression (p=0.030). Based on these observations, we conclude that GC patients with positive ABCB1 protein immunohistochemical expression in their tumors suffer shorter overall survival.

Association between the C3435T single-nucleotide polymorphism of multidrug resistance 1 gene and risk of gastric cancer

The multidrug resistance 1 (MDR1) gene encodes P-glycoprotein, which confers resistance to antineoplastic drugs, but also affects the kinetic disposition of certain drugs and carcinogens. The C3435T polymorphism of the MDR1 gene may influence the transport and excretion of carcinogens, increasing the risk of cancer. The aim of this study was to evaluate the association between this polymorphism and the risk of gastric cancer (GC). Ninety-eight patients with non-cardia GC and 203 healthy subjects participated in the study. DNA was extracted from leukocytes and the MDR1 polymorphism was analyzed using PCR-RFLP. Serology was performed by ELISA for the investigation of infection with Helicobacter pylori. No significant difference in the genotype (p=0.668) or allele (p=0.745) frequency of the C3435T polymorphism was observed between the GC and control groups. There was no association between the genotypes studied and the risk of GC in patients infected with H. pylori (p=0.662). Patient survival was not correlated with the genotypes studied (p=0.454). No correlation was observed between the C3435T polymorphism of the MDR1 gene and GC risk or prognosis in the population studied.

Establishment and Partial Characterization of an Epirubicin- Resistant Gastric Cancer Cell Line with Upregulated ABCB1

Multidrug resistance (MDR) is a major impediment to successful chemotherapy of gastric cancer. Our aim was to establish an epirubicin-resistant cell subline (AGS/EPI) and to elucidate the mechanisms involved in acquired EPI resistance. The AGS/EPI cell subline developed by exposing parental AGS cells to stepwise increasing concentrations of EPI demonstrated 2.52-fold resistance relative to the AGS cell line, and mRNA expression of the ATP-dependent drug-efflux pump P-glycoprotein (Pgp), more recently known as ABCB1 protein, was similarly upregulated. An AGS/EPI cell subline could thus be effectively established, and MDR mechanism of these cells was shown to be related to the overexpression of mRNA of the ABCB1 gene.

Genetic polymorphisms of vitamin D metabolism genes and serum level of vitamin D in colorectal cancer

Background The metabolism of vitamin D is complex, its receptor (VDR) and proteins encoded by the genes CYP27B2 and CYP24A1 can influence vitamin D serum levels. The aim of this study was to investigate the relationship of the polymorphisms of VDR (ApaI and BsmI), CYP27B1 and CYP24A1 with serum vitamin D levels in both forms, 25(OH)D3 (circulating form) and 1,25(OH)2D3 (active form), in colorectal cancer (CRC) patients. Methods One hundred fifty-two CRC patients and 321 controls were included. DNA was extracted from peripheral blood. Polymorphisms of BsmI and ApaI were identified by PCR-RFLP. Those of CYP24A1 (rs6013897, rs158552 and rs17217119) and CYP27B1 (rs10877012) were determined by gene sequencing. Results The median serum levels of circulating vitamin D were not different between CRC patients and controls; however, the percentage of those with deficient vitamin D was higher in patients with cancer. The active form of the vitamin D was higher in CRC patients. VDR, CYP27B1 and CYP24A1 polymorphic genotypes had no influence on serum levels of circulating vitamin D. The correlation between circulating and active vitamin D forms was lower among patients with CRC, regardless of the presence or absence of any genetic polymorphism. The mean serum levels of active vitamin D were higher among patients with polymorphic genotype variants of Apa1 or Bsm1. Conclusions CRC patients had a higher frequence of insufficient vitamin D and a higher concentration of active vitamin D. These concentration were higher between patients with polymorphic genotypes variants of ApaI and BsmI, CYP24A1 and CYP27B1. Polymorphic genotypes cause a lower correlation between the forms of vitamin D.

The influence of nutritional status and disease on adiponectin and TNF-α levels in colorectal cancer patients

BACKGROUND The aim of this study was to evaluate the association between adiponectin and tumor necrosis factor-α;(TNF-α;) serum levels in colorectal cancer (CRC) patients and compare these levels to clinical stage and nutritional status. METHODS A total of 79 patients were enrolled in the study (39 with CRC and 40 in the control). Nutritional status was assessed by Patient-Generated Subjective Global Assessment (PG-SGA), body mass index (BMI), and phase angle (PhA). Adiponectin and TNF-α;serum concentrations were determined using an enzyme-linked immunosorbent assay. RESULTS Serum adiponectin levels were higher among CRC patients (p = 0.001). TNF-α;serum levels were not significantly different between the groups, but patients with stage III or IV CRC had higher levels of TNF-α;than those with lower stage disease (p = 0.037). The three tools used for the assessment of nutritional status (BMI, PhA, and PG-SGA) demonstrated that patients with a more severe nutritional deficit had higher adipocytokine levels, although these differences were significant only to TNF- , when distributed PhA in tertiles. CONCLUSIONS Adiponectin levels were higher among CRC patients. Although TNF-α;serum levels from CRC patients did not differ significantly to the control group, CRC patients with stage III or IV had higher levels compared to those with stage I and II tumors. Nutritional status, as determined by BMI, PhA, and PG-SGA, demonstrated that patients with a greatest nutritional deficit, had higher levels of adipocytokines; however, these differences were significant only for TNF-, when distributed PhA in tertiles.