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The great majority of colorectal cancers have defects in the Wnt signaling pathway indicating that this pathway has an important role in carcinogenesis. Alterations in the β-catenin gene are observed in 10-50% of the patients with colorectal cancer. Mutations of the β-catenin gene frequently occur in a region coding the protein phosphorylation domain harboring the Ser33/37/Thr41 and Ser45 sites and the inhibition of phosphorylation. Disruption of the β-catenin regulation plays a critical role in tumor development. In this study, we analyzed expression and mutations of β-catenin and phosphorylation of the Ser45 and Ser33/37/Thr41 residues in the tumors and matched normal tissue samples of patients with colorectal cancer. We did not observe significant differences in the phosphorylation rates between the patients and the control group. Samples displaying different levels of phosphorylation in the tumor and normal tissue were analyzed for exon 3 mutations of the β-catenin gene. In three of 57 patients, a novel G to A substitution was found at codon 15. This nucleotide change has not been reported previously in the literature. β-catenin protein levels and the degree of Ser45 or Ser33/37/Thr41 phosphorylation in tumor and normal tissue were not associated with the clinical parameters. Our results indicate that differences in the expression and phosphorylation of β-catenin are not very frequent in colon cancer, but mutations in exon 3 of the β-catenin gene may be responsible for a significant proportion of the tumors.

Genetic factors that contribute to the risk of breast cancer are largely not known and association studies have revealed several genes with low penetrance risk alleles for breast cancer. Analysis of these genes may provide important information on the risk factors affecting carcinogenesis. Variations in the ARLTS1, RAD51 and MDM2 genes have been associated with increased risk of different cancer types but for breast cancer the results are not consistent. In this study we investigated the role of the allelic variants in candidate genes acting in the tumor suppressor, DNA repair and p53 pathways as risk factors for familial breast cancer in 147 patients displaying characteristics of familial disease. Presence of the polymorphic variants were investigated by amplification of the corresponding regions and restriction fragment length polymorphism analysis. Genotype and allele frequencies in the patients were significantly different for all three variants. Our results indicate that the polymorphic variants might affect individual susceptibility towards breast cancer.

Background: DNA methylation markers appear to be useful in cancer detection, in evaluating the prognosis associated with disease progression, and in detecting the metastatic potential of tumors., Methods: We present an approach for relative quantification of methylated gene sequences. The technique combines conventional PCR and LightCycler fluorescence PCR. In the conventional PCR step, bisulfite-modified molecules are selectively enriched, irrespective of their methylation status, and used as template in the second step, the LightCycler fluorescence PCR, which includes methylation-specific primers and fluorescently labeled probes. After amplification, a stepwise increase in temperature leads to the generation of melting curves reflecting fluorescence emission induced by disassociation of the probe-target complexes. Quantification is based on calculation of the peak areas for melting curves using a Gaussian fit curve. The area under this curve indicates the relative amounts of methylated sequences in each sample., Results: By normalizing the peak areas by template concentrations, a methylation index was calculated for each sample. This approach was then used to carry out a relative quantification of p16INK4A gene methylation in bone marrow and blood mononuclear cells from patients with positive translocation status., Conclusions: If validated in further studies, this approach represents a highly specific technique that can be used in analyzing paired samples of cancer patients.

Polymorphic variations may affect the rate of gene transcription, the stability of the mRNA, or the quantity and activity of the resulting protein. In this study we evaluated the association between the interleukin-1B C-31T, catechol-O-methyltransferase Val158Met, and thymidylate synthase (TS) 1494del6 polymorphisms and breast cancer. Each genetic polymorphism was investigated by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis. No significant difference in either the genotype distribution or the allelic frequencies of the IL-1B and COMT gene polymorphisms was observed between the patient and control groups. For the TS 1494del6 polymorphism a significant difference was observed for both the genotypes (P=0.01) and the allele frequencies (P=0.0097), indicating a decreased risk associated with the variant allele. Our data do not provide evidence for an association between the polymorphic variants of the IL-1B and COMT genes and breast cancer risk. On the other hand, the TS 1494del6 polymorphism is associated with a significantly lower risk of breast cancer and may be a potential genetic marker., (2007 Wiley-Liss, Inc.)

Background: Folate deficiency is implicated in cancer development. Single nucleotide polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene can modulate the effect of folate. In this case-controlled study, a possible effect of the common MTHFR C677T (ala-->val) polymorphism on breast cancer susceptibility in Turkish patients was investigated., Materials and Methods: Polymorphism analysis was performed by melting curve analysis., Results: The variant allele valine (677T) was more frequent among the patients (30.1%) than in controls (23.9%). This difference was weakly significant (p = 0.046; OR = 1.37) and due to a significantly higher frequency of the valine homozygotes (677TT) among the patients (12.1% vs. 5.4%; p = 0.013, OR = 2.5). Among the patients diagnosed at more than 40 years of age, a more pronounced association of the valine homozygotes with breast cancer risk was observed (p = 0.009; OR = 3.3)., Conclusion: Homozygosity for the low-activity C677T genotype (TT) may represent a genetic determinant increasing breast cancer risk.

The estrogen receptor (ER) and the human epithelial growth factor receptor 2 (HER2) genes have been implicated in the development and prognosis of breast cancer. Several genetic polymorphic sites in these genes have been identified and associated with the risk of breast cancer. We have investigated the association between the estrogen receptor codon 594 (ACA to ACG) and HER2 codon 655 (ATC to GTC) polymorphisms and breast cancer risk. Genomic DNA from breast cancer patients and control subjects was analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). When allelic frequencies of the ER codon 594 and HER2 codon 655 gene were compared, no significant differences were observed between the patient and control groups. (P = 0.063, OR = 1.55, 95% CI = 0.25-9.41 and P = 0.949, OR = 1.01, 95% CI = 0.55-1.88, respectively). In conclusion, our results support the view that both the ER codon 594 and HER2 codon 655 polymorphisms are not associated with increased risk of breast cancer.

Background: Methylenetetrahydrofolate reductase (MTHFR) plays a critical role in folate metabolism and displays common genetic polymorphisms affecting the enzyme activity. The MTHFR genetic polymorphisms have been associated with a decrease in the risk of developing the lymphoid but not myeloid form of pediatric and adult leukemias., Aim: In this study we describe the genotyping of the MTHFR C677T polymorphism by melting curve analysis with the LightCycler in a case-controlled study of patients with acute lymphocytic leukemia (ALL), myelogenous leukemia (AML), and chronic myelogenous leukemia (CML), and assess the effect of this common polymorphism on the leukemia risk in adult patients in Turkey., Methods: DNA from peripheral blood lymphocytes was used for genotyping in the LightCycler PCR by melting curve analysis. The risk of leukemia associated with the MTHFR polymorphism was evaluated by comparing the genotype frequencies between the control and patient groups., Results: The frequency of the homozygote variant genotype (677TT) was lower than that in healthy individuals in all three leukemia groups. The 677TT genotype did not appear to have a protective effect in patients with ALL (Odds ratio [OR] = 0.78 with a 95% confidence interval [CI] = 0.24-2.59), compared with healthy controls. The difference was higher (4.3-fold) in patients with AML, but still non-significant (OR = 0.23 with a 95% CI = 0.03-1.83). In patients with CML, the frequencies of both heterozygous (677CT) and homozygote variant genotypes were lower (OR = 0.72 and 0.66, respectively)., Conclusions: Our results suggest that the MTHFR C677T polymorphism displays a similar distribution pattern in lymphoid and myeloid leukemias and that the frequency of the homozygote variant genotype (677TT) is lower in all leukemia types.

CD44 is a cell surface glycoprotein expressed on different cell types that functions in lymphocyte activation and homing, extracellular matrix adhesion and cellular migration. CD44 is encoded by a single gene composed of at least 20 exons. The standard CD44 protein (CD44S or CD44H) is the hematopoietic form of CD44 in lymphoid cells. Variant isoforms (designated from v1 to v10) are formed by addition of new exons to the extracellular domain. High levels of CD44v6 expression has been observed in some tumors and are associated with metastatic spread. The aim of the present study was to investigate and evaluate expression of the CD44v6 and v6-containing variants as a possible marker in chronic myeloid leukemia and lymphoma by reverse transcription-polymerase chain reaction. CD44 exon v6 was detected in all patients and all individuals in the control group. CD44v6-v10 mRNA was observed in 25 patients but in none of the subjects in the control group. CD44v6/v9-10, CD44v6-v7, CD44v6/v10 transcripts were detected in 11, 6, and 2 patients, respectively. CD44v6-7/v9-10 transcripts were not observed in either the patients or the healthy individuals. We conclude that CD44v6-v10 expression may be associated with hematologic malignancies.