High potential of SOX21 gene promoter methylation as an epigenetic biomarker for early detection of colorectal cancer.

BACKGROUND: Despite the advances in screening during the past decades, colorectal cancer (CRC) still is a leading cause of cancer deaths worldwide. Therefore, the development of new diagnostic methods is necessary. AIM: The aim of this study was to compare methylation changes of SRY-Box 21 (SOX21) gene promoter in tumor tissues and their normal adjacent mucosa in patients with CRC and to examine the relationship between the methylation levels and demographic/clinicopathological factors. MATERIALS AND METHODS: A total of 41 CRC patients participated in the present study. After the extraction of DNA and bisulfite treatment of the samples, the methylation levels were determined by using the MethyLight method. STATISTICAL ANALYSIS: Two-sided Mann-Whitney U test was used to compare the median level of methylation in tumor tissues and their adjacent normal mucosa. RESULTS: The methylation rates in tumor tissue samples were significantly higher compared to their adjacent normal mucosa (P < 0.0001). No association between demographic/clinicopathological factors and methylation status observed in tumor tissues. A receiver operating characteristics curve was constructed and tissue samples exhibited a sensitivity of 80.5% and specificity of 97.6% for SOX21 promoter methylation. CONCLUSION: The results of this study indicated the high potential of SOX21 gene promoter methylation as a candidate noninvasive diagnostic biomarker in stool and plasma of colorectal cancer patients. However, further studies with larger sample sizes are required to evaluate the specific role of SOX21 methylation as a biomarker for early detection of CRC.

A Practical Non-Extraction Direct Liquid Chromatography Method for Determination of Thiopurine S-Methyltransferase Activity in Inflammatory Bowel Disease.

Thiopurine drugs remain pivotal therapies for the wide varieties of diseases such as inflammatory bowel disease (IBD). Here, thiopurine S-methyltransferase (TPMT) phenotype, the main metabolizing enzyme of thiopurine-drugs, was studied. This is for the first time that TPMT activity is measured in Iranian IBD patients. We used an improved direct liquid chromatography assay without need for solvent extraction and minimize excess labor handling making it ideal for use in routine referral medical centers. TPMT activity in whole blood was determined by a non-extraction HPLC method. We evaluated 427 individuals including 215 IBD patients and 212 unrelated healthy individuals as control group from Iran's western population. TPMT phenotyping of this study demonstrated no frequency for deficient, 2.8 % for low and 97.2% for normal activity, which is different with results of other studies. There was a significant negative correlation between TPMT activities as calculated based on nmol/grHb/h and the Hb-levels in IBD and control groups (r= -0.54, P<0.001 and r= -0.27, P<0.001), respectively. Interestingly a significant positive correlation between Hb levels and TPMT-activities were seen when the activity calculated in mU/L in IBD patients and control subjects (r=0.14, P=0.05 and r=0.43, P<0.001), respectively. We strongly suggest the use of international unit (mU/L) is more appropriate than nmol6MTG/grHb/h for expressing TPMT-activity in IBD patients. In addition, in comparison with other providers of TPMT test activity and centers around the world the risk of toxicity is much lower after utilizing thiopurine drugs for IBD patients in this region.

Whole-Blood Thiopurine S-Methyltransferase Genotype and Phenotype Concordance in Iranian Kurdish Ulcerative Colitis (UC) Patients.

BACKGROUND: Thiopurine methyl transferase (TPMT), a drug-metabolizing enzyme, catalyzes methylation and consequently, the metabolism of thiopurine compounds used for treatment of inflammatory bowel disease (IBD). Individuals who are homozygous recessive or have extremely low TPMT activity need to avoid thiopurines because of concern for significant leukopenia. The aim of this research was to determine TPMT phenotypes and genotypes in IBD patients to predict the risk of thiopurine toxicity before treatment. METHODS: The present case-control study consisted of 210 ulcerative colitis patients and 212 unrelated healthy controls from the population of western Iran. TPMT phenotype and genotype were determined by HPLC and allele specific PCR and PCR-RFLP, respectively. RESULTS: TPMT phenotyping and genotyping were compatible and demonstrated no frequency for deficient, 2.2% for low, and 97.8% for normal-activity which is different compared with the results of other studies. There was a significant negative correlation between TPMT activities as calculated based on nmol6MTG/gHb/h and the Hb levels in both UC (r = -0.54, p < 0.001) and control groups (r = -0.27, p < 0.001). Interestingly, a significant positive correlation between Hb levels and TPMT activities was seen when the enzyme activity was calculated in mU/L in both UC patients (r = 0.14, p = 0.05) and in control subjects (r = 0.43, p < 0.001). The overall concordance rate between TPMT phenotypes and genotypes of mutants to alleles (9 out of 422), based on receiver-operating characteristic (ROC) curve, yielded a sensitivity of 94.7% and specificity of 90% for mU/L and a sensitivity of 85.6% and specificity of 90% for nmol6MTG/gHb/h. CONCLUSIONS: The use of mU/L is more appropriate than nmol6MTG/gHb/h for expressing TPMT activity, and there is better correlation between genotypes and phenotypes of TPMT based on mU/L. The frequency of known mutant TPMT alleles in western Iran (Kurd population) is low suggesting low risk of thiopurine drug toxicity in IBD patients from this region.