fakhraddin naghibalhossaini

To investigate the effects of thymidylate synthase (TS) 3'UTR genotype on promotor methylation of tumor-related genes in 22 patients with sporadic colorectal cancer (CRC) from southern Iran. We evaluated the correlations of TS 3'UTR genotype with promoter methylation of hTERT, hMLH1, MSH2, MMP2, CDH1, p14, p16, and p21 genes in CRC patients. The polymorphism of TS 3′UTR was evaluated through mutagenically specific PCR. The genes promoter methylation was determined using methylation-specific PCR. For 10 patients, the gene expression profile of epigenetic regulating enzymes, histone deacetylases (HDACs) and DNA methyltransferases (DNMTs), was also examined in both tumor and normal adjacent tissues by quantitative real time PCR. There was a significant association between the hMLH1 methylation and age of patients (P= 0.039) and also between MSH2 methylation and tumor site (P= 0.036). There was insignificant association between gene-specific methylation and TS 3′UTR genotype. However, all polymorphic genotypes of TS were associated with higher methylation of hMLH1 and CDH1 and lower methylation of MSH2. The -6bp/+6bp (heterozygous mutant) and [-6bp/+6bp, +6bp/+6bp] (homozygous mutant) genotypes resulted in higher methylation of p16, and -6bp/+6bp and [-6bp/+6bp, +6bp/+6bp] genotypes were correlated with lower methylation of MMP2. The overexpression of epigenetic enzymes, HDACs and DNMTs, was also demonstrated. There was no association between DNMTs transcript levels and gene-specific hypermethylation. The polymorphic TS genotypes, especially -6bp/+6bp, could affect methylation frequencies of studied genes. Moreover, promoter methylation status was not dependent on DNMTs gene expression. Large sample size studies may contribute to validate these findings.

 Emerging evidence suggests that epigenetic mechanisms contribute to 5-fluorouracil (5-FU) resistance in colorectal cancer (CRC). However, there is limited research on the direct impact of 5-FU on epigenetic alterations in CRC. This study aimed to investigate how 5-FU treatment affects the expression of enzymes involved in epigenome regulation and promoter DNA methylation in human CRC cells.

 The viability of CRC cell lines (SW48, HCT116, LS180, and HT29) was evaluated after 48 hours of 5-FU treatment using MTT assay in both monolayer and hanging drop spheroid cultures. The cells were treated with an IC20 concentration of 5-FU and then the relative expressions of histone deacetylases (HDAC) and DNA methyltransferas1 (DNMT1) in 5-FU-treated and untreated cells were measured by quantitative RT-PCR (qRT-PCR). The status of promoter methylation of selected genes was analyzed using the methylation-specific PCR (MSP) method.

 The 3D cultures of cells were more resistant to 5-FU than their 2D counterparts. The effect of 5-FU on HDAC1 expression was greater in 3D cultures compared to 2D cultures. 5-FU downregulated SIRT1 and DNMT1 in 2D culture of HCT116 and SW48 and upregulated them in 3D cultures of HT29 and LS180 cells. In both monolayer and spheroid cultures, 5-FU downregulated HDAC2 in HCT116, LS180, and HT29 and HDAC4 in HCT116, LS180, and SW48 cells. 5-FU primarily changed promoter methylation in monolayer cultures.

 The epigenetic response to 5-FU is cell line-specific and depends on the culture method. 5-FU modulates epigenome in CRC cells by regulating DNMT1 and HDAC expressions. 3D cultures were found to be considerably more resistant to 5-FU-induced cytotoxicity and promoter DNA methylation changes than 2D cultures. 5-FU downregulated HDAC and DNMT1, particularly in the drug-sensitive cells, and increased the levels of DNMT1 in the drug-resistant cells.

Intense stress can change pain perception and induce hyperalgesia; a phenomenon called stress-induced hyperalgesia (SIH). However, the neurobiological mechanism of this effect remains unclear. The present study aimed to investigate the effect of the spinal cord µ-opioid receptors (MOR) and α2-adrenergic receptors (α2-AR) on pain sensation in rats with SIH.

Eighteen Sprague-Dawley male rats, weighing 200- 250 g, were randomly divided into two groups (n=9 per group), namely the control and stress group. The stress group was evoked by random 1-hour daily foot-shock stress (0.8 mA for 10 seconds, 1 minute apart) for 3 weeks using a communication box. The tail-flick and formalin tests were performed in both groups on day 22. The real-time RT-PCR technique was used to observe MOR and α2-AR mRNA levels at the L4-L5 lumbar spinal cord. Statistical analysis was performed using the GraphPad Prism 5 software (San Diego, CA, USA). Student’s t test was applied for comparisons between the groups. P<0.05 was considered statistically significant.

There was a significant (P=0.0014) decrease in tailflick latency in the stress group compared to the control group. Nociceptive behavioral responses to formalin-induced pain in the stress group were significantly increased in the acute (P=0.007) and chronic (P=0.001) phases of the formalin test compared to the control group. A significant reduction was also observed in MOR mRNA level of the stress group compared to the control group (P=0.003). There was no significant difference in α2-AR mRNA level between the stress and control group.

The results indicate that chronic stress can affect nociception and lead to hyperalgesia. The data suggest that decreased expression of spinal cord MOR causes hyperalgesia.

Pterygium is one of the most common eye conditions without any clear etiology. Some studies have suggested an association between sun exposure and pterygium, but others have proposed the role of genetic variations in its pathogenesis. To date, no study has investigated the association of inflammatory transcription factor, NFκB genes with pterygium in the Middle East. We examined the changes in expression of 3 inflammatory related NFκB1, NFκB2, and RELA genes in patients with pterygium. Thirty patients with pterygium and 30 age and sex-matched controls were enrolled in this case-control study. None of the participants showed any clinical signs of inflammation in their conjunctiva. Demographic information was obtained and the expression levels of three genes including NFκB1, NFκB2, and RELA were measured in their conjunctiva by real-time RT-PCR using gene-specific primers. Mean expression level of NFκB1, NFκB2 and RELA genes in patients were 2.4±0.3, 1.9± 0.5, and 1.8±0.4 times higher than normal subjects, respectively. Higher levels of gene expression were observed in individuals with more outdoor activity and sun exposure. Moreover, a significant correlation was observed between the expression levels of NFκB2 and RELA genes, suggesting a possible NFκB2- RELA heterodimer formation in patients with pterygium. This study has indicated a significant association between expressions of inflammatory-related NFκB1, NFκB2 and RELA genes, and pterygium. Further studies to verify the role of inflammation in the pathogenesis of pterygium, may provide new targets for managing pterygia.

Previous studies have suggested a protective role for Polyunsaturated Fatty Acids (PUFA) against cancer, cardiovascular, and other diseases. To provide new insights into the in vivo effects of PUFA on gene expression, the effects of dietary PUFA on DNMT3b and PPARα gene expression and global DNA methylation were investigated in selected rat tissues. Thirty sprague-dawley rats were allotted into 3 dietary groups of ten animals each, received experimental diets containing PUFAs every day by gavages for 12 weeks as follows: control group fed a normal diet and water; n-3 PUFAs group received 300 mg/kg/day n-3 PUFAs supplementation; mixed-PUFAs group received 300 mg/kg/day of a mixture of n-3, -6, -9 PUFAs supplementations. The expressions of DNMT3b and PPARα genes were quantitated using real-time RT-PCR. The genome-wide 5-methylcytosine contents in rat tissues were determined by ELISA method. The average expression of the DNMT3b mRNA was 50% lower in the colon and liver of rats fed the n-3- or mixed-PUFAs supplemented diet than control group (p=0.00). However, PPARα expression was significantly upregulated both in the colon and liver of PUFAs-supplemented rats (p<0.001). No significant difference was observed in the blood, colon, and liver DNA methylation levels between PUFAs-supplemented and control animals. The results indicate that dietary PUFAs could modulate the expressions of PPARα and DNMT3b genes in various rat tissues. The findings of this study provide additional insights into the in vivo mechanism of PUFA-mediated regulation of gene expression and could provide an opportunity to develop personalized diets for related disease control.

5-fluorouracil (5-FU) is one of the major components of many standard regimens for chemotherapy of colorectal cancer (CRC) and some other malignancies. Given the known relationship between thymidylate synthase (TS) and methylenetetrahydrofolate reductase (MTHFR) activity and 5-FU metabolism, this study investigated the impact of selected functional polymorphisms of the TS and MTHFR genes on chemotherapy resistance in 5 human CRC cell lines. HCT116, SW1116, HT29/219, LS180, and Caco-2 CRC cells were cultured as monolayer and their chemosensitivity to 5-FU, oxaliplatin, and irinotecan was determined by MTT assay. Genomic DNA was extracted from the cultured cells, and a 6-bp insertion or deletion (6-bp ins/del) polymorphism in 3´-UTR of the TS gene was determined by the PCR-RFLP method. Genotyping of MTHFR 677 C/T and 1298A/C single nucleotide polymorphism (SNP) was also performed by MS-PCR and PCR-RFLP, respectively. Caco-2 with the homozygous TS 6-bp ins/ins and MTHFR 677 T/T and 1298 C/C genotype, was the most 5-FU resistant cell line. HCT116 with the homozygous TS 6-bp del/del and MTHFR 1298 A/A and heterozygous MTHFR 677 C/T genotype was the least 5-FU resistant cell. LS180, the second most 5-FU resistant cell line, was heterozygous for all three polymorphic sits. HT29/219 and SW1116 cells with homozygous TS 6-bp ins/ins and heterozygous MTHFR 677 C/T and 1298 A/C genotypes had intermediate 5-FU sensitivity. The results indicate that TS 3´-UTR 6-bp insertion and MTHFR 677T and 1298C alleles increase 5-FU resistance in CRC cells. No relationship was observed between TS and MTHFR genotypes and oxaliplatin or irinotecan sensitivity in these cells.

Understanding the mechanism of tumor resistance is critical for cancer therapy. In this study, we investigated the effect of carcinoembryonic antigen (CEA) overexpression on UV-and 5-fluorouracil (5-FU)-induced apoptosis and autophagy in colorectal cancer cells. We used histone deacetylase (HDAC) inhibitor, NaB and DNA demethylating agent, 5- azacytidine (5-AZA) to induce CEA expression in HT29/219 and SW742 colorectal cancer cell lines. MTT assay was used to measure IC50 value of the cells exposed to graded concentrations of 5- FU with either 0.1 mM NaB or 1 μM 5-AZA for 72 h . Using CHO- and SW742-CEA transfectants, we also investigated the effect of CEA expression on UV- and 5-FU-induced apoptosis and autophagy. Treatment of HT29/219 cell line with NaB and 5-AZA increased CEA expression by 29% and 31%, respectively. Compared with control cells, the IC50 value for 5-FU of NaB and 5-AZA-treated cells increased by 40% and 57%, respectively. Treatment of SW742 cells with NaB or 5-AZA increased neither CEA expression nor the IC50 value for 5-FU. In comparison to parental cells, CEA expression also significantly protected transfected cells against UV-induced apoptosis. Decreased proportions of autophagy and apoptosis were also observed in 5-FU treated SW742- and CHO-CEA transfectants. We conclude that CEA expression can effectively protect colorectal cancer cells against radiation and drug-induced apoptosis and autophagy.

Multiple sclerosis (MS) is a demyelinating neuro- inflammatory autoimmune disease of the central nervous system. Genetic predisposition has long been suspected in the etiology of this disease. The association between MTHFR polymorphisms and MS has been ivestigated in different ethnic groups. We investigated the association between MTHFR C677T and A1298C missense variants and MS in 180 patients and 231 age- and gender-matched healthy controls in a Southern Iranian population. The mutagenically separated PCR (MS-PCR) and PCR-RFLP methods were used to genotype MTHFR at position 677 and 1298, respectively. Compared with controls, we observed a strong association between two MTHFR variants and the risk of developing MS. Subjects carrying 677T allele (CT and TT genotypes) had increased susceptibility to MS as compared to those carrying CC genotype (odds ratio (OR) for CT= 2.9, 95% confidence interval (95% CI)= 1.88-4.49; OR for TT= 6.23, 95% CI= 3.08-12.59). The variant 1298AC genotype also increased the risk for MS among our study population (OR= 2.14, 95% CI= 1.37-3.34). Combined genotype analysis for two MTHFR SNPs revealed that compared to the wild type genotypes (677CC/1298AA), 3 genotypes including TT/AC, CT/AC, and TT/AA were significantly at increased risk for MS development (OR= 13.9, 5.3, and 4.9, respectively). Our results suggest a possible gene dose- dependent association between MTHFR mutrant alleles and the risk of MS development.

Carcinoembryonic antigen (CEA), a glycophosphatidyl inositol (GPI) anchored glycoprotein, is over-expressed in various cancers, including colorectal carcinomas. Inhibition of cell differentiation can cause cancer. Previous studies show transfection and over-expression of CEA gene in myoblasts or colonocytes leads to inhibition of cell differentiation. We investigated whether soluble CEA has a role in inhibition of cell differentiation.

Monolayer cultures of L6, C2C12, Caco-2 and CHO cell lines were grown in dulbecco's modification of eagle's medium (DMEM) containing 10% fetal bovine serum (FBS). For differentiation induction C2C12 and L6 cell lines media, was changed to DMEM containing 2% horse serum. CEA concentration was measured in harvested media by ELISA assay. H&E staining, CK assay and RT-PCR for myogenin gene were used for C2C12 differentiation experiments.

The results showed although commercial pure CEA and LS-180 conditioned media (contain high level of CEA) have inhibitory effects on Caco-2 differentiation, but it can also inhibit differentiation of control groups. We observed the effect of high concentration of CEA (5μg/ml) on L6 differentiation is identical with the effect of BSA as control. C2C12 differentiation was inhibited in response to LS-180 conditioned media at morphological level and myogenin expression. CK activity was significantly lower in LS-180 conditioned media (P= 0.0012) and CHO (P= 0.0002) conditioned media groups in comparison to control group.

Our finding shows soluble CEA antigen did not have a significant effect on cell differentiation.