The effects of thymidylate synthase 3'UTR genotype on methylation of tumor-specific genes promoter in 22 colorectal cancer patients from southern Iran.

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.

Bilirubin, an endogenous antioxidant that affects p53 protein and its downstream apoptosis/autophagy-related genes in LS180 and SW480 cell culture models of colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) is one of the commonest neoplasms worldwide, which its pathogenesis is strongly correlated with p53 mutations. Antioxidants are believed to decelerate the CRC progression, possibly through interfering with p53 and its downstream target genes and mechanisms. Regarding the potential antioxidant effects of bilirubin, as an incredible endogenous antioxidant, we sought to investigate how bilirubin affected the expression levels of p53 protein and its downstream target genes, including Mdm2, Bcl-2, BECN1 and LC3, in LS180 and SW480 cell culture models of CRC. METHODS AND RESULTS: Using the MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazolium bromide) assay, 50 and 100 µM concentrations of bilirubin were determined to be non-toxic for both LS180 and SW480 cell lines. Western blot analysis was employed to evaluate the protein expression levels of p53. The results revealed that p53 protein levels were higher in LS180 cells treated with bilirubin compared to the control group. Notwithstanding, in SW480 cells, no considerable changes were observed in p53 protein levels of treated cells compared to the control ones. The quantitative reverse transcriptase-polymerase chain reaction (q RT-PCR) method was used to measure the mRNA expression levels of the apoptosis/autophagy-related genes, Mdm2, Bcl-2, BECN1, and LC3 , as the p53's downstream target genes. Consequently, the expression of Bcl-2 and Mdm2 genes were affected by p53, while BECN1 and LC3 expression levels were decreased in both cell lines. CONCLUSION: Bilirubin is an endogenous antioxidant with significant anti-tumor effects in the studied CRC cell lines, probably through the regulation of p53 protein expression levels and subsequent control of apoptosis and autophagy, as two key processes involved in cell survival and progression of tumor cells.

PIWI interacting RNAs perspectives: a new avenues in future cancer investigations.

As a currently identified small non-coding RNAs (ncRNAs) category, the PIWI-interacting RNAs (piRNAs) are crucial mediators of cell biology. The human genome comprises over 30.000 piRNA genes. Although considered a new field in cancer research, the piRNA pathway is shown by the existing evidence as an active pathway in a variety of different types of cancers with critical impacts on main aspects of cancer progression. Among the regulatory molecules that contribute to maintaining the dynamics of cancer cells, the P-element Induced WImpy testis (PIWI) proteins and piRNAs, as new players, have not been broadly studied so far. Therefore, the identification of cancer-related piRNAs and the assessment of target genes of piRNAs may lead to better cancer prevention and therapy strategies. This review articleaimed to highlight the role and function of piRNAs based on existing data. Understanding the role of piRNA in cancer may provide perspectives on their applications as particular biomarker signature in diagnosis in early stage, prognosis and therapeutic strategies.

A Significant Breakthrough in the Incidence of Childhood Cancers and Evaluation of its Risk Factors in Southern Iran.

BACKGROUND AND OBJECTIVE: This study investigates epidemiologic and practical information about the incidence and risk factors of childhood cancer in a population of Southern Iranian children. MATERIALS AND METHODS: A total number of 300 cancer patients along with 600 age- and gender-matched healthy control were interviewed by a trained physician regarding their demographic characteristics, and major family-associated risk factors, childhood malignancies. RESULTS: The average annual percentage change for cancers in the studied population is calculated as 45%. Our study indicated that possible risk factors which could contribute to the development of childhood cancer are maternal oral contraceptive pill use during pregnancy, exposure to radiation during pregnancy, parental smoking, residence near high voltage electricity lines, exposure to pesticides and fertilizers, patient allergy, contact with domestic animals and father's educational degree. Furthermore, new ecological risk factors such as air pollution due to nonstandard petroleum or toxic inhalant particles, nonhealthy food consumption, and satellite jamming are other predisposing factors. CONCLUSION: Our study reported a higher average annual percentage change of childhood cancers in our area, compared to the existing literature. In conclusion, detection and prevention of the consistent and possible new environmental risk factors such as nonstandard petroleum or satellite jamming from all around the country should be taking into consideration.