Combined epigenetic/genetic study identified an ALS age of onset modifier

Age at onset of amyotrophic lateral sclerosis (ALS) is highly variable (eg, 27-74 years in carriers of the G4C2-expansion in C9orf72). It might be influenced by environmental and genetic factors via the modulation of DNA methylation (DNAm) at CpG-sites. Hence, we combined an epigenetic and genetic approach to test the hypothesis that some common single nucleotide polymorphisms (SNPs) at CpG-sites (CpG-SNPs) could modify ALS age of onset. Our genome-wide DNAm analysis suggested three CpG-SNPs whose DNAm levels are significantly associated with age of onset in 249 ALS patients (q < 0.05). Next, genetic analysis validated the association of rs4970944 with age of onset in the discovery (n = 469; P = 0.025) and replication (n = 4160; P = 0.007) ALS cohorts. A meta-analysis of the cohorts combined showed that the median onset in AA-carriers is two years later than in GG-carriers (n = 4629; P = 0.0012). A similar association was observed with its tagging SNPs, implicating a 16 Kb region at the 1q21.3 locus as a modifier of ALS age of onset. Notably, rs4970944 genotypes are also associated with age of onset in C9orf72-carriers (n = 333; P = 0.025), suggesting that each A-allele delays onset by 1.6 years. Analysis of Genotype-Tissue Expression data revealed that the protective A-allele is linked with the reduced expression of CTSS in cerebellum (P = 0.00018), which is a critical brain region in the distributed neural circuits subserving motor control. CTSS encodes cathepsin S protein playing a key role in antigen presentation. In conclusion, we identified a 16 Kb locus tagged by rs4970944 as a modifier of ALS age of onset. Our findings support the role of antigen presenting processes in modulating age of onset of ALS and suggest potential drug targets (eg, CTSS). Future replication studies are encouraged to validate the link between the locus tagged by rs4970944 and age of onset in independent ALS cohorts, including different ethnic groups.

The Intersection between COVID-19, the Gene Family of ACE2 and Alzheimer's Disease

We reviewed factors that might influence COVID-19 outcomes (eg, neurological symptoms), including the link to Alzheimer's disease. Since the virus triggers COVID-19 infection through binding to ACE2, we focused on the ACE2 gene family, including ACE. Both ACE2 and ACE are involved in the renin-angiotensin system (RAS). In general, ACE causes inflammation and vasoconstriction, while ACE2 leads to anti-inflammation activity and vasodilation. The disturbed balance between these counter-regulatory pathways could influence susceptibility to COVID-19. Notably, dysregulation of the RAS-equilibrium contributes to Alzheimer's disease. Differences in the incidence and symptoms of COVID-19 in diverse populations could be attributed to variability in the human genome. For example, ACE and ACE2 variations could modify the outcome of COVID-19 in different populations. It would be important to conduct genome-wide studies to detect variants influencing COVID-19 presentation, with a special focus on variants affecting immune-related pathways and expression of RAS-related genes.

Extreme heat exposure in pregnancy and risk for preterm birth, low birth weight and stillbirths

Background

Exposure to high ambient temperatures during pregnancy may increase the risk of adverse pregnancy outcomes due to physiological and anatomical changes in pregnancy compromising the ability to thermoregulate.

Methods

A systematic review and meta-analysis of studies that assessed associations between ambient heat, and preterm birth, birth weight and stillbirths. Articles were identified through a search of Medline (PubMed) and Web of Science. Titles and abstracts were screened, eligible studies extracted and risk of bias assessed using the Joanna Briggs Institute appraisal tools.

Results

14,880 records were screened and a total of 70 studies included. In 40 of 47 studies, preterm births were more frequent at higher than lower temperatures. In random effects meta-analysis, the odds of a preterm birth rose 1.05-fold per 1 °C increase in temperature (95%CI=1.03, 1.07), and 1.16 fold during heat waves (95%CI=1.10, 1.23). Reduced birth weight associated with higher temperature was found in in 18 of 28 studies, with considerable heterogeneity. Studies on stillbirths (n = 8) all showed temperature-stillbirth associations, with stillbirths increasing 1.05-fold per 1 °C rise in temperature (95%CI=1.01, 1.08). Associations between temperature and outcomes were largest among women in lower socioeconomic groups and at age extremes. The multiple temperature metrics and lag analyses limited comparison between studies and settings.

Conclusions

As frequency of heat exposures is increasing, prevention for pregnant women during heat waves should become a standard aspect of heat adaptation.

Key messages

Increase in extreme temperature events may have major implications for child health unless much more is done to provide heat adaptation services for pregnant women. Links between socio-economic status and study outcomes suggest higher vulnerability for already disadvantaged groups.

miR-130b is a potent stimulator of hepatic very-low-density lipoprotein assembly and secretion via marked induction of microsomal triglyceride transfer protein

miR-130b is a microRNA whose expression is particularly elevated within adipose tissue and in the circulation in diabetic states. Hepatic miR-130b expression has been linked to hepatocellular carcinoma and changes in lipid metabolism. Here, we investigated the role of miR-130b in hepatic lipid homeostasis and lipoprotein export. We observed that overexpression of miR-130b-3p or -5p in HepG2 cells markedly enhanced the secretion of very-low-density lipoprotein (VLDL) particles, enhanced the secretion of [³H]glycerol metabolically labeled triglyceride (TG), and significantly increased the number or the average size of lipid droplets (LDs), respectively. Overexpression of miR-130b also altered the expression of key genes involved in lipid metabolism and in particular markedly increased both mRNA and protein expression levels of microsomal triglyceride transfer protein (MTP). Conversely, the miR-130b inhibitor decreased mRNA levels of MTP and fatty acid synthase (FAS) in HepG2 cells. However, dual-luciferase reporter assays indicated that MTP is not a direct target of miR-130b-3p. miR-130b overexpression did not alter de novo synthesized TG or the stability and secretion of apolipoprotein B 100. Interestingly, knockdown of phosphatase and tensin homolog (PTEN) blocked the upregulation of MTP mRNA induced by miR-130b. Finally, miR-130b-induced stimulation of VLDL secretion was also observed in a second hepatocyte cell culture model, immortalized human hepatocytes, confirming the effects observed in HepG2 cells. Overall, these data suggest a potential role for miR-130b in promoting hepatic VLDL assembly and secretion mediated by marked stimulation of MTP expression and TG mobilization. Thus miR-130b overexpression corrects the defect in VLDL production in HepG2 cells.

The association between SMAD7 polymorphisms and colorectal cancer susceptibility as well as clinicopathological features in the Iranian population

AIM

Our aim was to investigate the association between two single nucleotide polymorphisms (SNPs) of SMAD7 and the risk of CRC among Iranian individuals.

BACKGROUND

Genome-wide association studies (GWAS) have identified 18q21 as a risk locus for colorectal cancer (CRC), which maps to the SMAD7 gene.

METHODS

This case-control study was conducted on 109 CRC cases and 109 controls in the Iranian population to evaluate the influence of two SNPs of SMAD7, rs2337106 and rs6507874, on the risk of CRC as well as on clinicopathological features. Genotype determination was performed by TaqMan assay via an ABI 7500 Real Time PCR System (Applied Biosystems) for the DNA of peripheral blood. Descriptive analysis and logistic regression model were used for statistical analyses.

RESULTS

Genotyping of the SNPs in the SMAD7 gene revealed that the frequency of G allele of rs2337106 was 53.7% in controls and 56.4% in cases (p-value=0.564) while the frequency of C allele of rs6507874 was 55.5% in controls and 56.3% in cases (p-value=0.772). Further, there were no significant differences in genotype frequencies of these SNPs between CRC patients and controls. The SMAD7 genotypes were not associated with the risk of CRC or with any clinicopathological characteristics such as tumor site, tumor grade, and stage TNM in CRC patients (p-value>0.05), even after adjustment for sex, age, and smoking status.

CONCLUSION

Our results provided the first evidence that SMAD7 genotypes, rs2337106 and rs6507874, could not be predisposing markers in genetic susceptibility to CRC in an Iranian population, at least in the studied population.

Single Nucleotide Polymorphism (A870G) of the CCND1 gene: association with colorectal cancer susceptibility

AIM

The aim of this study is to demonstrate the role of CCND1 gene polymorphism, A870G, in susceptibility to sporadic colorectal cancer in Iranian population.

BACKGROUND

It has been distinguished that CCND1 gene is one of the main genes in Wnt signaling pathway which involves in generating colorectal cancer. Nonetheless, there is no consistent result in terms of association between the genetic variations of this gene and colorectal cancer risk.

METHODS

We designed a case-control study consisting of 100 subjects with colorectal cancer (CRC) and 100 healthy controls to investigate the effect of A870G polymorphism on CRC susceptibility in an Iranian population. Genotype determination was performed by PCR-RFLP method.

RESULTS

The frequency of GG, AG and AA genotypes for cases were 24%, 51% and 25% respectively, while the genotype frequency for controls were 21%, 50% and 29% respectively. It was identified that there is no significant association between A870G polymorphism and risk of CRC, even after adjusting sex, age and smoking status variables (P = 0.777; OR=1.32 95% CI: 0.6-2.93)..

CONCLUSION

Despite the well-known role of CCND1 gene in cell cycle regulation, our results revealed that A870G polymorphism could not be a potential predisposing risk factor in genetic susceptibility to CRC, at least in the studied population.

Novel Missense Mutation at Codon 2774 (C.8321 G>A) p.S2774N of APC Gene in a Denovo Case of Familial Adenomatous Polyposis

Familial adenomatous polyposis (FAP) is an autosomal dominant inherited disease caused by germline mutation in Adenomatous Polyposis Coli (APC) gene. FAP accounts less than 1% of all colorectal cancers incidence. Patients generally present hundreds to thousands of adenomas in colon and rectum and develop colorectal cancer by age 35 - 40 if left untreated. A milder form of FAP with fewer numbers of polyps (< 100) is Attenuated FAP (AFAP) and in comparison with classical FAP, it usually diagnosed at an older age. Approximately 15% - 20% of FAP patients are ''de novo'' cases without any family history of the disease and novel APC mutations account for approximately 25% of FAP cases. In our study, we reported a novel missense mutation at the APC gene in a denovo patient with AFAP like phenotype.

Lack of influence of the SMAD7 gene rs2337107 polymorphism on risk of colorectal cancer in an Iranian population

SMAD7 has been identified as a functional candidate gene for colorectal cancer (CRC). SMAD7 protein is a known antagonist of the transforming growth factor beta (TGF-β) signaling pathway which is involved in tumorigenesis. Polymorphisms in SMAD7 may thus alter cancer risk. The aim of this study was to investigate the influence of a SMAD7 gene polymorphism (rs2337107) on risk of CRC and clinicopathological features in an Iranian population. In total, 210 subjects including 105 patients with colorectal cancer and 105 healthy controls were recruited in our study. All samples were genotyped by TaqMan assay via an ABI 7500 Real Time PCR System (Applied Biosystems) with DNA from peripheral blood. The polymorphism was statistically analyzed to investigate the relationship with the risk of colorectal cancer and clinicopathological properties. Logistic regression analysis revealed that there was no significant association between rs2337107 and the risk of colorectal cancer. In addition, no significant association between genotypes and clinicopathological features was observed (p value>0.05). Although there was not any association between genotypes and disorder, CT was the most common genotype in this population. This genotype prevalence was also higher in the patients with well grade (54.9%) and colon (72.0%) tumors. Our results provide the first evidence that this polymorphism is not a potential contributor to the risk of colorectal cancer and clinicopathological features in an Iranian population, and suggests the need of a large-scale case-control study to validate our results.

The prostaglandin synthase 2/cyclooxygenase 2 (PTGS2/ COX2) rs5277 polymorphism does not influence risk of colorectal cancer in an Iranian population

BACKGROUND

The prostaglandin-endoperoxide synthase 2 [PTGS2, commonly known as cyclooxygenase-2 (COX-2)] is an enzyme induced by proinflammatory stimuli that is often overexpressed in malignant tissue and involved in the synthesis of prostaglandins and thromboxanes, regulators of processes such as inflammation, cell proliferation, and angiogenesis, all relevant for cancer development. We investigated whether a functional genetic polymorphism, rs5277, in COX-2 may have a risk-modifying effect on sporadic colorectal cancer in an Iranian population.

MATERIALS AND METHODS

We conducted a case-control study on 167 patients with colorectal cancer and 197 cancer-free controls in Taleghani Hospital in Tehran, Iran, between 2007 and 2011. Peripheral blood samples of both groups were processed for DNA extraction and genotyping of the COX-2 gene polymorphism (rs5277) using PCR-RFLP. RFLP results were confirmed by direct sequencing. Logistic regression analysis was performed to calculate the adjusted odds ratio (OR) and 95% confidence interval (95% CI).

RESULTS

There was no significant difference in the distribution of COX-2 gene rs5277 polymorphism genotype and the allelic form, among CRC patients compared with the healthy control group (p: 0.867).

CONCLUSIONS

Our results suggest that rs5277 polymorphism in COX2 could not be a good prognostic indicator for patients with CRC.

Molecular analysis of imperative polymorphisms of MLH1 gene in sporadic colorectal cancer

BACKGROUND

Single nucleotide polymorphisms in mismatch repair genes may be associated with different protein expression, production, and efficiency according to allele status and influence the risk of developing colorectal cancer.

OBJECTIVE

This research aimed at analyzing two important polymorphisms in MLH1 gene and their association in colorectal cancer susceptibility.

METHODS

In total, 219 CRC patients and 248 healthy controls were genotyped with PCR/RFLP for I219V and IVS12-169 C>T polymorphisms in MLH1 gene. Sequencing performed to ensure work flow and results. We used unconditional logistic regression after adjusting for age and sex to evaluate the association between each polymorphism and colorectal cancer.

RESULTS

The MLH1 I219V polymorphism was associated with colorectal cancer susceptibility (P=0.01). Stratified data analysis for gender demonstrated association of AG (P=0.009) and GG (P=0.021) genotypes with risk of colorectal cancer in women. In contrast there is no association with IVS 12-169 C>T polymorphism and colorectal cancer risk.

CONCLUSIONS

I219V SNP might be a susceptibility factor for CRC and gender is a factor that must be considered when it is analyzing. Further tests need to be done to define it as a dependable prognosis factor.

Telomere shortening: a biological marker of sporadic colorectal cancer with normal expression of p53 and mismatch repair proteins

Uncontrolled growth of cells, a main criterion of cancer, is merged with pathologic telomere length alteration. Thereby, measurement of telomere length could provide important information on cell proliferation and senescence in cancer tissues. Telomere shortening and its potential correlation with clinicopathological predictive markers in sporadic colorectal cancer (CRC) with normal expression of mismatch repair (MMR) proteins (including Mlh1, Msh2, Pms2, and Msh6) and normal p53 expression was completely explored. Relative telomere length (RTL) was quantitatively measured in a cohort of 164 samples (68 patients with sporadic CRC and 96 healthy unrelated controls). Our results demonstrated a significant shortening of RTL in the tumor-derived tissue of patients compared with the control group (p<0.001). Interestingly, significant telomere shortening was observed in tumors from an ascending and sigmoid colon in comparison with tumors located in a descending colon. Additionally, the telomere length was significantly shorter in those with lymph node metastasis (p<0.05). The results suggest that pathological telomere shortening, leading to genome instability and lymphatic transformation, could serve as a potential sensitive detection and also as a classification marker for facilitating diagnosis and management of CRC.

Correlation between the EGF gene intronic polymorphism, rs2298979, and colorectal cancer

Colorectal cancer (CRC) is an important disorder that results from genetic and epigenetic alterations in one colonic epithelial cell. Epidermal growth factor (EGF) is critical in the development of tumors in epithelial tissues. Variations in the DNA sequence of the EGF gene may be particularly significant with regard to susceptibility to CRC. The present study aimed to investigate the effect of the EGF gene single nucleotide polymorphism (SNP), rs2298979, on CRC. In this prospective study, 220 samples were collected from patients with CRC and compared with 220 matched healthy controls. Genotyping was performed using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method, and the result was validated by direct sequencing. A significant correlation was observed between the rs2298979 variant in the EGF gene and CRC. The frequency of the A/G genotype in the control group was higher than in the patients with sporadic CRC [odds ratio (OR), 0.488; 95% confidence interval (CI), 0.307–0.774; P=0.002]. In this study there were no individuals with a G/G genotype. Although the frequency of the G and A alleles was similar in the healthy control and CRC patient groups, individuals with the A/G genotype were less susceptible to CRC compared with those with the A/A genotype.

Different frequency of epidermal growth factor rs76189946 polymorphism genotype in an Iranian colorectal cancer

AIM

This study aimed to determinant association between rs76189946 polymorphism of EGF gene and risk of colorectal cancer in an Iranian population.

BACKGROUND

Colorectal cancer (CRC) is the third most prevalent cancer in both genders worldwide. The determination of genetic variation becomes a new way to etiology of colorectal cancer. Epidermal growth factor (EGF) is a mitogen that plays an important role in cell growth and tumourigenesis, this protein acts by binding its receptor, EGFR.

PATIENTS AND METHODS

DNA samples taken from totally 125 CRC patients and healthy controls were amplified by polymerase chain reaction (PCR) for the rs76189946 polymorphism. Genotypes were analyzed using restriction fragment length polymorphism (RFLP). Finally to confirm the RFLP procedure, 20 of the PCR products were sequenced using the ABI PRISM 3130xl Genetic Analyzer and chain termination method (Applied Biosystems, Carlsbad, CA).

RESULTS

Genotype distribution and allele frequency was similar in CRC patients and controls individuals. We expect observe C and G allele in both groups but only was found C allele.

CONCLUSION

In this study for first time we identified genetic distribution of exonic rs76189946 polymorphism in EGF gene both CRC patients and healthy controls. These results suggest there wasn't association between EGF polymorphism rs76189946 and risk of colorectal cancer in an Iranian population.

Clinical implications of BRAF mutation test in colorectal cancer

Knowledge about the clinical significance of V-Raf Murine Sarcoma Viral Oncogene Homolog B1 (BRAF) mutations in colorectal cancer (CRC) is growing. BRAF encodes a protein kinase involved with intracellular signaling and cell division. The gene product is a downstream effector of Kirsten Ras 1(KRAS) within the RAS/RAF/MAPK cellular signaling pathway. Evidence suggests that BRAF mutations, like KRAS mutations, result in uncontrolled, non-growth factor-dependent cellular proliferation. Similar to the rationale that KRAS mutation precludes effective treatment with anti-EGFR drugs. Recently, BRAF mutation testing has been introduced into routine clinical laboratories because its significance has become clearer in terms of effect on pathogenesis of CRC, utility in differentiating sporadic CRC from Lynch syndrome (LS), prognosis, and potential for predicting patient outcome in response to targeted drug therapy. In this review we describe the impact of BRAF mutations for these aspects.

The effect of 5'untranslated region polymorphism in EGF gene, rs4444903, on colorectal cancer

AIM

The purpose of this study was to determine the relationship of rs4444903 (EGF+61A/G) SNP genotype with colorectal cancer and tumor stage in an Iranian population.

BACKGROUND

Epidermal growth factor (EGF) is one of the important proteins that determine survival of cells. EGF binds to its receptor on the cell surface and then activates some of the cell signaling pathway networks within cells that lead to activation or deactivation of factors which are responsible for growth and apoptosis of cells. In this study we assessed the association in EGF polymorphism rs4444903 with colorectal cancer (CRC) in Iranian population.

PATIENTS AND METHODS

We conducted case-control study to investigate the association of polymorphism rs4444903 in EGF, with colorectal cancer risk in Iranian population. Analyzed Polymorphism of EGF rs4444903 with restriction fragment length polymorphisms (RFLP) among two groups of subjects consisting of including 220 cases with colorectal cancer and 220 healthy individuals as controls. Mutations were confirmed in 10% of the samples by direct sequencing.

RESULTS

The frequencies of AA, AG and GG genotypes among cases with colorectal cancer were 28.2, 46.8, and 25.0 % respectively and in controls genotype frequencies were 23.2, 56.4, and 20.5 %, respectively. Frequency of A allele among case group was 51.6% and for control group was 51.4%. The frequency of G allele in case and control was, respectively 48.4% and 48.6% (OR= 1.009, 95% CI= 0.775-1.315; P= 0.946). The percentage of Stage 0, I, II, III, IV were 5%, 9.35%, 38.84%, 30.21% and 16.54%, respectively, among the cases. However, no significant association between this polymorphism and CRC stage was observed (p=0.626).

CONCLUSION

Our data suggest a SNP rs4444903 may not represent a risk factor in the development and progression of CRC among Iranian population.

Prevalence of ATP7B Gene Mutations in Iranian Patients With Wilson Disease

BACKGROUND

Wilson disease (WD) is an autosomal recessive disorder. The WD gene, ATP7B, encodes a copper-transporting ATPase involved in the transport of copper into the plasma protein ceruloplasmin and in excretion of copper from the liver. ATP7B mutations cause copper to accumulate in the liver and brain.

OBJECTIVES

We examined the ATP7B mutation spectrum in Wilson disease patients in Iran.

PATIENTS AND METHODS

Genomic DNA was extracted from patients with Wilson disease. The entire coding region of the ATP7B gene was amplified using PCR and analyzed using direct sequencing.

RESULTS

We identified five novel mutations in 5 Iranian patients with Wilson disease. The first was a transversion, c.2363C > T, which led to an amino acid change from threonine to isoleucine. The second mutation was a deletion, c.2532delA (Val845Ser), which occurred in exon 10. The third mutation was a transition mutation, c.2311C > G (Leu770Leu), which occurred in the TM4 domain of the ATP7B protein. The fourth mutation was a transversion, (c.3061G > A) (Lys1020Lys), in exon 14. Lastly, we identified a transversion, c.3206C > A (His1069Asn) in exon 14 which led to a change in function of the ATP loop domain of the ATP7B protein. The H1069Q mutation was identified as the most common mutation in our study population.

CONCLUSIONS

Based on our findings, the H1069Q may be a biomarker that can be used in a rapid detection assay for diagnosing WD patients.

The role of kras mutations and MSI status in diagnosis of colorectal cancer

AIM

The aim of the current investigation was to examine the profile of Kras mutations accompanied with MSI (microsattelite instability) status in polyps and colorectal carcinoma tissues in an Iranian population.

BACKGROUND

Kras mutations in colorectal cancer cause resistance to anti-Epidermal Growth Factor Receptor (EGFR). So it can be considered as a true indicator of EGFR pathway activation status. Kras mutations can be detected in approximately 30% to 40% of all patients with colorectal cancer. The most hot spot of the gene is located in exons 2 and 3.

PATIENTS AND METHODS

In this study we examined exons 2 and 3 Kras gene using polymerase chain reactions and subsequent sequencing of the exons in 95 patients with sporadic colorectal cancer including 48 tumors and 47 polyps. This study was performed using biopsy samples from the patients. We sequenced the Kras gene in a panel of human colorectal tumors and polyps in addition to detecting MSI status using fluorescent technique.

RESULTS

We could detect 6 mutations in tumors including 5 mutations in codon 12 and one mutation in codon 13. Moreover, in polyps 2 mutations were determined in codon 13 and one in codon 12. Microsatellite instability assay revealed the presence of 5 and 6 MSI in tumors and polyps, respectively. Among the MSI mononucleotide markers, NR-21 marker demonstrated the most frequency (60%) in the both groups.

CONCLUSION

Our findings showed that probably the profile of mutations in tumors is not entirely compatible with the pattern of mutations in polyps. However, just one of the mutations, Gly12Asp, was similar in both groups.

Simplified MSI marker panel for diagnosis of colorectal cancer

BACKGROUND

Colorectal cancers (CRCs) tumors are diagnosed by microsatellite instability (MSI) due to accumulation of insertion/deletion mutations in tandem repeats of short DNA motifs (1-6 bp) called microsatellites. Microsatellite instability (MSI) is not only a hallmark marker for screening of hereditary nonpolyposis colorectal cancer (HNPCC), but also a prognostic and predictive marker for sporadic colorectal cancer. Our objective was to determine and study of five mononucleotide microsatellite markers status among Iranian patients with HNPCC and sporadic colorectal cancer.

MATERIALS AND METHODS

In the current investigation 80 sporadic CRC and 80 HNPCC patients were evaluated for MSI. The pentaplex panel including 5 quasimonomorphic mononucleotide repeats (NR-21, BAT-26, BAT-25, NR-27 and NR-24) was used.

RESULTS

Our findings showed that the NR-21 was the most frequent instable marker among the other markers. 53% and 25.6% specimens had instability in sporadic CRC and HNPCC, respectively. Furthermore, the frequencies of instability BAT-25 was determined in 20% sporadic CRC and 23% HNPCC samples. Interestingly our results demonstrated that the frequency of instability NR-24 was similar 20% sporadic CRC and 20.5% HNPCC. Moreover, percentage of NR-27 in HNPCC was 19.2 and 0% in sporadic CRC. Finally, BAT-26 was instable in 21.8% HNPCC patients while we could find 6.6% instability for BAT-26 in sporadic cases.

CONCLUSION

It seems that among 5 mononucleotides markers NR-21 was the most useful marker for diagnosis HNPCC and sporadic cancer. Following NR-21, BAT-25 and NR-24 are the most reliable markers. Therefore using a triplex panel including 3 aforementioned MSI markers should be more promising markers for identifying MSI status in both patients with HNPCC and/or sporadic colorectal cancer.

Impact of EXO1 polymorphism in susceptibility to colorectal cancer

BACKGROUND AND AIM

One candidate gene for colorectal cancer (CRC) susceptibility is exonuclease 1 (EXO1). It is a member of RAD2 nuclease family, which plays a major role in mismatch repair, DNA replication, and recombination. Single-nucleotide polymorphisms are shown to be related with cancer incidence. The aim of the present study was to examine the association between the L757P polymorphism at exon 13 of the EXO1 gene and the risk of CRC in Iranian patients.

METHODS

In this case-control study, 90 cases and 98 healthy control samples were analyzed genetically. The EXO1 polymorphism, P757L, was analyzed by polymerase chain reaction-restriction fragment length polymorphism. The obtained polymorphisms were examined for the relationship with CRC risk and also clinicopathological characteristics.

RESULTS

Our findings showed that patients with the Leu/Leu genotype have a reduced risk of CRC (adjusted odds ratio [OR] = 0.192, 95% confidence interval [CI]: 0.040-0.921) when the Pro/Leu and Pro/Pro genotypes were blended and they were considered as the reference. The Leu/Leu genotype also showed a reduced risk (adjusted OR = 0.168, 95% CI: 0.034-0.816) when the Pro/Pro genotype was a reference; nevertheless, the Pro/Leu genotype did not reveal a significant association with CRC at the same status (adjusted OR = 0.686, 95% CI: 0.367-1.284).

CONCLUSIONS

Our results provide evidence diagnosing that the Leu/Leu genotype of EXO1 showed an inverse association with CRC. In addition, despite other investigations, we could define a significant association between the Leu allele and CRC (p = 0.001).

Association between MTHFR polymorphism (C677T) with nonfamilial colorectal cancer

The enzyme 5,10-methylene-tetrahydrofolate reductase (MTHFR) is linked to DNA methylation, synthesis, and repair. C677T is one of the most important polymorphisms in the MTHFR gene. The single nucleotide polymorphism C677T has been found to be associated with decreased enzyme activity and plasma folate, and thus may play a crucial role in the etiology of colorectal cancer. This decrease was observable in people with either high or low folate status. We aimed to test the hypothesis that the C677T genotype is involved in colorectal cancer. Using pyrosequencing, we analyzed the MTHFR genotypes in 234 colorectal cancer patients and 257 matched controls. We examined the polymorphisms in MTHFR and folate intake in relation to risk of colon cancer in an Iranian population-based case-control study. Our finding revealed that the CC, CT, and TT genotypes of MTHFR among the colorectal cancer patients were 50%, 29.1%, and 20.9%, respectively. On the other hand, we could find 29.5% of 677CC, 46% of 677CT and 24.5% of 677TT in the controls. A decreased risk of colon cancer for participants with wild-type genotype was observed. Interestingly, this association was stronger at higher levels of folate intake. Our study corroborates previous findings of an inverse association of the MTHFR 677TT genotype with colorectal cancer, in particular at high levels of folate.

Frequent MSI mononucleotide markers for diagnosis of hereditary nonpolyposis colorectal cancer

BACKGROUND

Failure in the DNA mismatch repair system is commonly accompanied by microsatellite instability and leads to colorectal cancer. The aim of this study was to find the most frequent of five mononucleotide markers in order to devise the simplest diagnostic strategy for identification of patients with hereditary nonpolyposis colorectal cancer (HNPCC) who were defined by defects in mismatch repair system.

MATERIALS AND METHODS

78 patients with colorectal cancer were recruited for this investigation. Five mononucleotide markers, NR-27, NR-21, NR-24, BAT-25 and BAT-26, were used as a pentaplex panel to determine MSI status.

RESULTS

Two out of five mononucleotide markers, NR-21 (25.6%) and BAT-25 (23.1%) showed more instability than the others.

CONCLUSION

In defining individuals with colorectal cancer, BAT25 and NR-21 may provide diagnostic assistance.

Comparison of survival between patients with hereditary non polyposis colorectal cancer (HNPCC) and sporadic colorectal cancer

BACKGROUND

Hereditary non polyposis colorectal cancer (HNPCC) appears to have a better prognosis than sporadic cancer. In the present study we evaluated the clinical outcomes of HNPCC patients with their sporadic colorectal cancer counterparts arising from the general population recorded in a population-based cancer registry in Iran.

PATIENTS AND METHODS

The population studied consisted of 121 individuals including 61 patients with sporadic colorectal cancer and 60 with HNPCC who were followed-up between 2003 and 2008 in Taleghani Hospital Tehran. The subjects with HNPCC were screened according to Amsterdam criteria II and Bethesda Guidelines. Subjects with sporadic cancer had no familial history of colorectal cancer. Observed survival was estimated using the Kaplan-Meier method and compared with the log rank test. Multivariate analysis was performed using Cox' regression analysis.

RESULTS

In the HNPCC group, 85.0% showed tumors in the colon, vs. 68.9% in the sporadic cancer group. The 5-year survival was 82.5% in the HNPCC study group compared with only 56.4% in the sporadic colorectal cancer group (P= 0.044). The age distribution at diagnosis of sporadic patients was significantly higher than HNPCC patients (mean 50.1 years vs 44.3 years P= 0.008). The hazard ratio for sporadic cases was 2.93 (95% CI 1.06-8.11) compared with the HNPCC group (P= 0.038).

CONCLUSION

Our findings corroborate the results of previous studies which showed overall survival of colorectal cancer in patients with HNPCC is better than with sporadic CRC patients.

Methylation profiles of 22 candidate genes in breast cancer using high-throughput MALDI-TOF mass array

Alterations of DNA methylation patterns have been suggested as biomarkers for diagnostics and therapy of cancers. Every novel discovery in the epigenetic landscape and every development of an improved approach for accurate analysis of the events may offer new opportunity for the management of patients. Using a novel high-throughput mass spectrometry on matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) silico-chips, we determined semiquantitative methylation changes of 22 candidate genes in breast cancer tissues. For the first time we analysed the methylation status of a total of 42 528 CpG dinucleotides on 22 genes in 96 different paraffin-embedded tissues (48 breast cancerous tissues and 48 paired normal tissues). A two-way hierarchical cluster analysis was used to classify methylation profiles. In this study, 10 hypermethylated genes (APC, BIN1, BMP6, BRCA1, CST6, ESRb, GSTP1, P16, P21 and TIMP3) were identified to distinguish between cancerous and normal tissues according to the extent of methylation. Individual assessment of the methylation status for each CpG dinucleotide indicated that cytosine hypermethylation in the cancerous tissue samples was mostly located near the consensus sequences of the transcription factor binding sites. These hypermethylated genes may serve as biomarkers for clinical molecular diagnosis and targeted treatments of patients with breast cancer.

Comparison of survival between patients with hereditary non polyposis colorectal cancer (HNPCC) and sporadic colorectal cancer

BACKGROUND

Hereditary non polyposis colorectal cancer (HNPCC) appears to have a better prognosis than sporadic cancer. In the present study we evaluated the clinical outcome of HNPCC patients with respect to that of patients with colorectal cancer recorded in a population-based cancer registry. Aim of our study was to examine survival rates in Iranian HNPCC patients with colorectal cancer and compare them with survival rates of sporadic cases arising from the general population.

PATIENTS AND METHODS

The population studied consists of 121 individuals including 61 patients with sporadic colorectal cancer and 60 patients with HNPCC who were followed-up between 2003 and 2008 in Taleghani hospital Tehran. The subjects with HNPCC were screened according to Amsterdam criteria II and Bethesda Guidelines. All those with sporadic cancer had no familial history of colorectal cancer. Observed survival was estimated using the Kaplan-Meier method and compared with log rank test. Multivariate analysis was performed using the Cox regression analysis.

RESULTS

In the HNPCC group, 85.0% showed tumors in colon, vs. 68.9% in the sporadic cancer group. The 5-year survival was 82.5% in the HNPCC study group compared with only 56.4% in the general population group (P= 0.044). The age distribution at diagnosis of sporadic patients was significantly higher than HNPCC patients (mean 50.1 years vs 44.3 years P= 0.008). The hazard ratio for sporadic for tumor location was 3.233 (95% CI 1.123-9.307) compared with the HNPCC group (P= 0.030).

CONCLUSION

Our findings corroborate the results of previous study which showed overall survival of colorectal cancer in patients with HNPCC is better than sporadic CRC patients.

High-throughput hacking of the methylation patterns in breast cancer by in vitro transcription and thymidine-specific cleavage mass array on MALDI-TOF silico-chip

Over the last decade, the rapidly expanding interest in the involvement of DNA methylation in developmental mechanisms, human diseases, and malignancies has highlighted the need for an accurate, quantitative, and high-throughput assay. Existing methods are limited and are often too laborious for high-throughput analysis or inadequate for quantitative analysis of methylation. Recently, a MassCLEAVE assay has been developed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to analyze base-specific methylation patterns after bisulfite conversion. To find an efficient and more cost-effective high-throughput method for analyzing the methylation profile in breast cancer, we developed a method that allows for the simultaneous detection of multiple target CpG residues by using thymidine-specific cleavage mass array on matrix-assisted laser desorption/ionization time-of-flight silicon chips. We used this novel quantitative approach for the analysis of DNA methylation patterns of four tumor suppressor genes in 96 breast tissue samples from 48 patients with breast cancer. Each individual contributed a breast cancer specimen and corresponding adjacent normal tissue. We evaluated the accuracy of the approach and implemented critical improvements in experimental design.

Mitochondrial DNA content in paired normal and cancerous breast tissue samples from patients with breast cancer

INTRODUCTION

We develop a multiplex quantitative real-time PCR for synchronized analysis of mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) to investigate relative mtDNA abundance in paired normal and cancerous breast tissues.

MATERIALS AND METHODS

The amounts of nDNA and mtDNA in 102 tissue samples were quantified for both glyceraldehype-3-phosphodehydrogenase (GAPDH) gene and mtDNA encoded ATPase (MTATP) 8 gene. The average threshold cycle (Ct) number values of the nDNA and mtDNA were used to calculate relative mtDNA content in breast tissues.

RESULTS

The median delta Ct (DeltaCt) and the median mtDNA content for normal and cancerous breast tissues were 6.73 and 2.54, as well as 106.50 and 5.80 (P = 0.000, respectively). The mtDNA content was decreased in 82% of cancerous breast tissues compared with the normal ones. The changes were associated with hormone receptor status.

CONCLUSION

Our finding suggests that decreased mtDNA content in breast cancer may have diagnostic and prognostic value for the disease.

Association between the 1793G> A MTHFR polymorphism and sporadic colorectal cancer in Iran

BACKGROUND

It has been proposed that folate and polymorphisms of the enzyme methylenetetrahydrofolate reductase (MTHFR), which regulates influx of folate for methylation reactions for DNA synthesis and repair, are involved in colorectal cancer. This study was designed to determine the influence of a genetic variant (MTHFR G1793A) and folate on colon cancer in Iran.

MATERIALS AND METHODS

We analyzed 227 cases and 239 normal unmatched controls using pyrosequencing. Odds ratios and 95% confidence intervals (95% CI) were calculated to evaluate associations of the MTHFR gene polymorphism with colorectal cancer risk.

RESULTS

A significantly reduced risk of recurrence was observed in patients heterozygous for the MTHFR G1793A polymorphism (OR: 0.17; 95% CI, 0.05-0.52). The frequency of GG, GA and AA genotypes of MTHFR among the colorectal cancer patients were 98%, 2% and 0% respectively, while the frequencies among controls were 90%, 10% and 0%, respectively. Furthermore, a significant reduction in recurrence risk was seen in MTHFR G1793A heterozygotes limited to those who received folate supplements.

CONCLUSION

Our study is compatible with previous findings concerning a reverse association between the MTHFR 1793G> A genotype with cancers in different populations.