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Colorectal cancer is the third cause of cancer and the second leading cause of death worldwide. The CD44 gene plays a key role in malignant processes, including growth, survival, epithelial to mesenchymal transition and metastasis. It is also known that some variants as rs187116 (c.67+4883G>A) and rs7116432 (c.2024+779A>G) can modulate the function of the CD44 gene and malignant transformation in several neoplasms. This study aims to explore, for the first time, the association of the CD44 rs187116 and rs7116432 variants in patients with colorectal cancer. Genomic DNA from 250 patients and 250 healthy blood donors were analyzed. The identification of variants was made by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methodology. Association was calculated by the odds ratio (OR) test and multivariate analysis. Individuals carrying the G/A and A/A genotypes for the rs187116 polymorphism showed an increased risk for colorectal cancer (OR = 3.11, 95% CI: 1.87-5.16, P = 0.001 and OR = 3.59, 95% CI: 2.06-6.25, P = 0.001, respectively). After adjusting for age and gender, these same genotypes and the G/G genotype of the rs7116432 polymorphism were associated with TNM stage and tumor location in the colon. Moreover, the A-G (rs187116 and rs7116432) haplotype was associated with increased risk; while, the haplotype G-A (rs187116 and rs7116432) was related with decreased risk. In conclusion, our results suggest that the here analyzed CD44 variants are involved with risk, TNM stage and tumor location in colorectal cancer.

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of death worldwide. The named "destruction complex" has a critical function in the Wnt/β-catenin pathway regulating the level of β-catenin in the cytoplasm and nucleus. Alterations in this complex lead to the cellular accumulation of β-catenin, which participates in the development and progression of CRC. This study aims to determine the contribution of polymorphisms in the genes of the β-catenin destruction complex to develop CRC, specifically adenomatous polyposis coli (APC) (rs11954856 G>T and rs459552 A>T), axis inhibition protein 1 (AXIN1) (rs9921222 C>T and rs1805105 C>T), AXIN2 (rs7224837 A>G), and dishevelled 2 (DVL2) (2074222 G>A and rs222836 C>T). Genomic DNA from 180 sporadic colorectal cancer patients and 150 healthy blood donors were analyzed. The identification of polymorphisms was made by polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP) methodology. Association was calculated by the odds ratio (OR) test. Increased susceptibility to CRC was associated with the polymorphic variants rs11954856 (APC), rs222836 (DVL2), and rs9921222 (AXIN1). Decreased susceptibility was associated with the polymorphisms rs459552 (APC) and 2074222 (DVL2). Association was also observed with advanced Tumor-Node-Metastasis (TNM) stages and tumor location. The haplotypes G-T in APC (rs11954856-rs459552) and A-C in DVL2 (rs2074222-rs222836) were associated with decreased risk of CRC, while the G-T haplotype in the DVL2 gene was associated with increased CRC risk. In conclusion, our results suggest that variants in the destruction complex genes may be involved in the promotion or prevention of colorectal cancer.

Molecular diagnosis of fragile X syndrome (FXS) is carried out by Southern blot or polymerase chain reaction-Southern analysis; however, these procedures are expensive and time consuming, making it impractical for mass screening programs. Willemsen et al. developed and tested the diagnostic potential of a rapid antibody test on blood smears, based on the presence of fragile X mental retardation protein ( FMRP) in peripheral lymphocytes from normal individuals and its absence in male patients with FXS. The diagnostic power of this antibody test is perfect for men, whereas the results are less specific for women. Validation of this procedure has been achieved mainly in the Caucasian population, but no reports including Latin American individuals have been published. To test this procedure, expression of FMRP in peripheral lymphocytes was achieved both in Mexican FXS patients and normal men and was compared with the molecular analysis of the CGG repetitive sequences of the FMR1 gene. The results of the antibody test, which measure the FMRP expression, entirely correlated with the molecular tests using polymerase chain reaction on DNA modified. Sensitivity and specificity of the test and the positive and negative predictive values were 100%. This noninvasive test requires one or two blood drops; it is rapid, simple, and inexpensive, making this procedure an ideal choice for screening large groups of male patients with mental retardation.

Fragile X syndrome is the most common cause of inherited mental retardation; it is caused by expansion of CGG repeats in the first exon of the FMR1 gene. The number of CGG repeats varies between 6 and 50 triplets in normal individuals; the most common alleles have 29 or 30 repeats. Allelic patterns in the global populations are similar; however; some reports show statistical differences among several populations. In Mexico, except by a single report on a western Mestizo population, the allelic frequencies of the FMR1 gene are unknown. In this study, we analyze 207, 140, 138, and 40 chromosomes from Mestizos, Tarahumaras, Huichols, and Purepechas respectively. After PCR amplification on DNA modified by sodium bisulfite treatment, molecular analysis of the FMR1 gene showed 30 different alleles among the 525 chromosomes evaluated. Trinucleotide repeat number in the different Mexican populations varied from 15 to 87, with modal numbers of 32 and 30 in Mestizos and Tarahumaras, 29 and 32 in Purepechas and 30 among Huichols. Together, these allelic patterns differ significantly from those reported for Caucasian, Chinese, African, Indonesian, Brazilian, and Chilean populations. The increased number of the unusual allele of 32 repeats observed in the Mexican mestizo population can be explained from its frequency in at least two Mexican native populations. Am. J. Hum. Biol., 2008. © 2008 Wiley-Liss, Inc.

A group of mutations characterized by trinucleotide repeat expansion causes human diseases such as the Fragile X syndrome, Huntington disease (HD), and myotonic dystrophy. Methods based on PCR amplification of the CGG and CAG repeats region could facilitate the development of a rapid screening assay; unfortunately, amplification across CGG and CAG repeats can be inefficient and unreliable due to the G + C base composition. The utility of the PCR on modified DNA for amplification of the CGG and CAG repeats at the Fragile X syndrome and HD has been reported. In the present study, we analyzed the utility of PCR on modified DNA as a rapid screening method for diagnosis of patients with Fragile X syndrome and HD. A comparative analysis realized with 38 Fragile X and 29 HD patients showed that the molecular diagnosis by simple PCR on modified DNA has a sensitivity and specificity of 100% in Fragile X patients and 94.1% and 91.6% in HD patients. The results achieved from the statistical analysis allowed us to conclude that the amplification by simple PCR on modified DNA is a reliable and useful method for the molecular diagnosis of the Fragile X syndrome, but not for the HD.

Background Fragile X syndrome is the most frequent cause of inherited mental retardation; it is caused by expansion of CGG repeats in the first exon of the FMR1 gene. Number of CGG repeats varies between 6 and 50 triplets in normal individuals and the most common alleles have 29 or 30 repeats. Allelic patterns in the global population are similar; however, some reports show statistical differences among several populations. Distribution of allelic frequencies for FMR1 locus has not been reported in Mexican population. Methods Determination of the CGG repeat number was achieved by polymerase chain reaction (PCR) on modified DNA from 129 unrelated Mexican mestizos (46 FRAXA-negative males with mental retardation and 83 healthy individuals). DNA modification by sodium bisulfite achieves conversion of unmethylated cytosine residues to uracil, which allows efficient amplification by single PCR. Methylation status of FMR1 region for each individual was also established. DNA sequencing of a number of amplified samples was realized to validate the procedure. Results Molecular analysis of the FMR1 gene showed 23 different alleles. Statistical comparison of allelic length between healthy and affected individuals does not show significant differences. Trinucleotide repeat number varied from 16–40, with modal number of 32 (27.58%), second peak at 30 (25.28%), and minor peak at 34 (10.34%). Together, allelic distribution in the Mexican sample differs significantly from those reported for Caucasian, Chinese, African, Indonesian, Brazilian, Chilean, and Mixtec populations. An excess of large alleles (≥34 repeats) was evident. Conclusions Allele distribution in FMR1 gene from Mexican mestizos is different from that of other reported populations around the world. This unusual modal pattern probably is related to the particular ethnic background of the Mexican population. On the other hand, PCR on modified DNA is a valuable and efficient method for determination of CGG repetitive sequences in FMR1 gene.

Background and Aims Although sporadic cases of cancer in patients with fragile X syndrome (FXS) have been reported, extensive studies carried out in Denmark and Finland concluded that cancer incidence in these patients is lower than in the general population. On the other hand, the FMR1 protein, which is involved in the translation process, is absent in FXS patients. Hence, it is reasonable to assume that these patients exhibit an abnormal expression of some proteins involved in regulating tumor suppressor genes and/or oncogenes, thus explaining its decreased cancer frequency. We undertook this study to analyze the expression of oncogenes and tumor suppressor genes in fragile X syndrome patients. Methods Molecular analysis of the FMR1 gene was achieved in 10 male patients and controls. Total RNA from peripheral blood was used to evaluate expression of oncogenes and tumor suppressor genes included in a 10,000 gene microarray library. Quantitative real-time PCR was utilized to confirm genes with differential expression. Results Among 27 genes showing increased expression in FXS patients, only eight genes exhibited upregulation in at least 50% of them. Among these, ARMCX2 and PPP2R5C genes are tumor suppressor related. Likewise, 23/65 genes showed decreased expression in >50% of patients. Among them, WNT7A gene is a ligand of the β-catenin pathway, which is widely related to oncogenic processes. Decreased expression of WNT7A was confirmed by quantitative RT-PCR. Expression of c-Myc , c-Jun , cyclin-D and PPARδ genes, as target of the β-catenin pathway, was moderately reduced in FXS patients. Conclusions Results suggest that this diminished expression of the WNT7A gene may be related to a supposed protection of FXS patients to develop cancer.

Introduccion. Actualmente se conoce un grupo de mutaciones por la expansion de tripletes de nucleotidos, los cuales resultan muy inestables en meiosis y mitosis. Cuatro tipos de tripletes tienen capacidad de expansion patogenica en seres humanos (CGG/GCC, CAG/GTC, CTG/GAC y GAA/CTT) y pueden localizarse tanto en secuencias codificadoras (atrofia muscular bulboespinal, enfermedad de Huntington y algunas ataxias espinocerebelosas) como no codificadoras (sindrome X fragil, ataxia de Friedreich, distrofia miotonica). La expansion trinucleotida puede producir ganancia o perdida de la funcion genica y parece asociarse a una variedad de factores, algunos directamente relacionados con el proceso expansivo (cis-actuantes) y otros cuya interaccion con los tripletes contribuye a su inestabilidad (trans-actuantes). Las expansiones de tamano intermedio (premutaciones), aunque clinicamente silentes, muestran una marcada tendencia a expandirse a mutaciones completas durante la transicion por linea germinal. Los modelos propuestos para explicar la expansion de tripletes involucran los procesos de replicacion y recombinacion genica; sin embargo, no han logrado explicar por completo los fenomenos relacionados con la mutacion o la expresion fenotipica en estas enfermedades. Desarrollo. Este trabajo examina los conceptos mas recientes en relacion a los procesos de mutacion dinamica causantes de enfermedades humanas y revisa los mas importantes aspectos clinicobiologicos observados en estas. Conclusiones. Los procesos de mutacion dinamica representan un nuevo concepto en la biologia molecular de las mutaciones genicas. Un numero continuamente creciente de patologias son causadas por este tipo de alteraciones en el ADN, las cuales muestran, en conjunto, caracteristicas clinicobiologicas muy interesantes.

Background WNT7a, a member of the Wnt ligand family implicated in several developmental processes, has also been reported to be dysregulated in some types of tumors; however, its function and implication in oncogenesis is poorly understood. Moreover, the expression of this gene and the role that it plays in the biology of blood cells remains unclear. In addition to determining the expression of the WNT7A gene in blood cells, in leukemia-derived cell lines, and in samples of patients with leukemia, the aim of this study was to seek the effect of this gene in proliferation. Methods We analyzed peripheral blood mononuclear cells, sorted CD3 and CD19 cells, four leukemia-derived cell lines, and blood samples from 14 patients with Acute lymphoblastic leukemia (ALL), and 19 clinically healthy subjects. Reverse transcription followed by quantitative Real-time Polymerase chain reaction (qRT-PCR) analysis were performed to determine relative WNT7A expression. Restoration of WNT7a was done employing a lentiviral system and by using a recombinant human protein. Cell proliferation was measured by addition of WST-1 to cell cultures. Results WNT7a is mainly produced by CD3 T-lymphocytes, its expression decreases upon activation, and it is severely reduced in leukemia-derived cell lines, as well as in the blood samples of patients with ALL when compared with healthy controls (p ≤0.001). By restoring WNT7A expression in leukemia-derived cells, we were able to demonstrate that WNT7a inhibits cell growth. A similar effect was observed when a recombinant human WNT7a protein was used. Interestingly, restoration of WNT7A expression in Jurkat cells did not activate the canonical Wnt/β-catenin pathway. Conclusions To our knowledge, this is the first report evidencing quantitatively decreased WNT7A levels in leukemia-derived cells and that WNT7A restoration in T-lymphocytes inhibits cell proliferation. In addition, our results also support the possible function of WNT7A as a tumor suppressor gene as well as a therapeutic tool.

Background Fragile X Syndrome (FXS) and its associated disorders are caused by the expansion of the CGG repeat in the 5’ untranslated region of the fragile X mental retardation 1 (FMR1) gene, with disease classification based on the number of CGG repeats. The mechanisms of repeat expansion are dependent on the presence of cis elements and the absence of trans factors both of which are not mutually exclusive and contribute to repeat instability. Expansions associated with trans factors are due to the haploinsuffient or reduced expression of several DNA repair/metabolizing proteins. The reduction of expression in trans factors has been primarily conducted in animal models without substantial examination of many of these expansion mechanisms and trans factors in humans. Results To understand the trans factors and pathways associated with trinucleotide repeat expansion we have analyzed two microarray datasets which characterized the transcript expression in patients with FXS and in controls. Conclusion We observed significant down regulation of DNA damage/repair pathway transcripts. This observation was consistent in both datasets, which used different populations. Within these datasets, several transcripts overlapped in the direction of association and fold change. Further characterization of these genes will be critical to understand their role in trinucleotide repeat instability in FXS.