Search

The present study aimed to analyze the methylation pattern of the MIR200 family in the colorectal tissues and peripheral blood of colorectal cancer (CRC) patients. Previous informed consent, 102 samples of colorectal tissues (tumor and adjacent normal tissues) and 40 peripheral blood samples were collected from CRC patients. Additionally, we included a reference group of 40 blood samples. DNA extraction was done for colorectal tissues and peripheral blood. For methylation-specific PCR, we used bisulfite-treated DNA and controls for methylated and unmethylated DNA were included to each assay. PCR fragments were separated by 6% polyacrylamide gel electrophoresis. Methylation-positive and methylation-negative results were confirmed by bisulfite genomic sequencing technique. We analyzed 102 colorectal tissues and 40 blood samples from 51 CRC patients. MIR200B/MIR200A/MIR429 methylation analysis discloses no differences among tissues (p>0.05). However, MIR200C/MIR141 methylation showed differences between colorectal tissues and peripheral blood of CRC patients (p

This study aimed to investigate the frequency of the somatic BRAF p. V600E in patients with colorectal cancer (CRC) in Mexico and compare it with those estimated for Latin American and Caribbean populations. One hundred and one patients with CRC with AJCC stages ranging I-IV from Western Mexico were included, out of which 55% were male and 61% had AJCC stage III-IV, with a mean age of 60 years. PCR-Sanger sequencing was used to identify the BRAF p. V600E variant. In addition, a systematic literature search in PubMed/Medline database and Google of the 42 countries in Latin America and the Caribbean led to the collection of information on the BRAF p. V600E variant frequency of 17 population reports. To compare the BRAF variant prevalence among populations, a statistical analysis was performed using GraphPad Prism V.6.0. We found that 4% of patients with CRC were heterozygous for the p. V600E variant. The χ2 test showed no significant difference (p>0.05) in p. V600E detection when comparing with other Latin American and Caribbean CRC populations, except for Chilean patients (p=0.02). Our observational study provides the first evidence on the frequency of BRAF p. V600E in patients with CRC from Western Mexico, which is 4%, but increases to 7.8% for all of Latin America and the Caribbean. The patient mean age and genetic descent on the observed frequencies of the variant in populations could influence the frequency differences.

The ZNF217 gene, a potential oncogene amplified and overexpressed in several cancers including colorectal cancer (CRC), acts as a transcription factor that activates or represses target genes. The polymorphisms rs16998248 (T>A) and rs35720349 (C>T) in coronary artery disease have been associated with reduced expression of ZNF217. In this study, we analyzed the 2 polymorphisms in Mexican patients with CRC. Genotyping of rs16998248 and rs35720349 sites was performed by polymerase chain reaction-restriction fragment length polymorphism in 203 Mexican Mestizos, 101 CRC patients, and 102 healthy blood donors. Although no statistical differences regarding genotype and allele frequencies of ZNF217 polymorphisms were observed (P > 0.05), linkage disequilibrium was significant in CRC patients (r(2) = 0.39, P < 0.0001), as a result of reduced AC haplotype frequency. Thus, the AC haplotype may protect against CRC.

We analyzed a possible association between RUNX3 gene polymorphisms and haplotypes in Mexican patients with colorectal cancer (CRC). Genomic DNA samples were obtained from the peripheral blood of 176 Mexican patients with CRC at diagnosis and from 195 individuals that formed the control group. The polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism. Association was estimated by odds ratio (OR). The haplotypes and linkage disequilibrium were established using the Arlequin v3.5 software. We found that the RUNX3 polymorphisms analyzed were in Hardy-Weinberg equilibrium. The RUNX3 rs2236852 AA genotype and A allele showed association with CRC (OR = 0.39, 95%CI = 0.21-0.73, P < 0.01; OR = 0.65, 95%CI = 0.49-0.87, P < 0.01, respectively), while the rs6672420, rs11249206, and rs760805 polymorphisms did not show significant association with CRC. The TA haplotype (SNPs rs760805 and rs2236852) showed an increased risk for CRC (OR = 2.52, 95%CI = 1.47-4.30, P < 0.001). In conclusion, we found that the AA genotype and A allele of rs2236852 polymorphism confer a decreased CRC risk, while the TA haplotype appears to increase the risk of CRC development in Mexican patients.

DNA repair proteins maintain DNA integrity; polymorphisms in genes coding for these proteins can increase susceptibility to colorectal cancer (CRC) development. We analyzed a possible association of MLH1 -93GA and 655AG and XRCC1 Arg194Trp and Arg399Gln polymorphisms with CRC in Mexican patients. Genomic DNA samples were obtained from peripheral blood of 108 individuals with CRC (study group) at diagnosis and 120 blood donors (control group) from Western Mexico; both groups were mestizos. The polymorphisms were detected by PCR-RFLP. Association was estimated by calculating the odds ratio (OR). We found that the MLH1 and XRCC1 polymorphisms were in Hardy- Weinberg equilibrium. The MLH1 655AG polymorphism in the 655G allele was associated with a 2-fold increase risk for CRC (OR = 2.04 and 95% confidence interval (95%CI) = 1.12-3.69; P0.01), while the MLH1 -93GA polymorphism allele was associated with a protective effect (OR = 0.60, 95%CI = 0.40-0.89; P = 0.01 in the -93A allele and OR = 0.32, 95%CI = 0.13-0.79; P = 0.01 in the AA genotype). The XRCC1 Arg194Trp and Arg399Gln polymorphisms did not show any significant associations. In conclusion, we found that MLH1 -93GA and 655AG polymorphisms are associated with CRC in Mexican patients.

Leptin and adiponectin are cytokines produced by adipose tissue with opposite effects on tumor growth: the former stimulate whereas the latter inhibit it. The objective was to analyze the association of LEP A19G and ADIPOQ+45 T/G and +276 G/T polymorphisms in Mexican patients with colorectal cancer (CRC). 68 unrelated patients with CRC (study group) and 102 blood donors (control group); all subjects were Mestizos from western Mexico. The polymorphisms were established by PCR-RFLP on DNA samples obtained from peripheral blood. The LEP A19G polymorphism showed significant differences between CRC patients and control group (p= 0.01 for G/A genotype and p= 0.02 for the recessive model G/G +G/A); yet, in the analysis stratified by gender, this difference remained significant only in males. The ADIPOQ polymorphisms did not shown any significant differences. Our results suggest that the A19G LEP polymorphism is associated with CRC in Mexican patients.

To determine the influence of the MDR1 C3435T polymorphism on the development of childhood acute lymphoblastic leukemia (ALL), we studied 107 children with ALL and 111 healthy subjects. All subjects were genotyped for the C3435T polymorphism using the polymerase chain reaction-restriction fragment length polymorphism method. The genotype frequencies in the patients were 17% homozygous CC, 61% heterozygous CT, and 22% homozygous TT; in healthy individuals the genotype frequencies were 14% CC, 53% CT, and 33% TT. In patients with ALL the allele frequencies were 0.47 for the C allele and 0.53 for the T allele; in the healthy group these allele frequencies were 0.40 and 0.60 for the C and T alleles, respectively. No significant differences in allele frequency (p > 0.176) and genotype frequency (p > 0.255) were detected between the two groups. These findings suggest that the CT or TT genotype does not increase the risk for childhood ALL in Mexican patients. On the other hand, significant differences in allele frequencies were detected in the comparison of Mexican healthy subjects with other populations. Whether these differences are fortuitous or related to diverse genetic backgrounds remains to be elucidated.