Genetic Variants of HOTAIR Associated with Colorectal Cancer: A Case-Control Study in the Saudi Population.

Genetic polymorphism in long noncoding RNA (lncRNA) HOTAIR is linked with the risk and susceptibility of various cancers in humans. The mechanism involved in the development of CRC is not fully understood but single nucleotide polymorphisms (SNPs) can be used to predict its risk and prognosis. In the present case-control study, we investigated the relationship between HOTAIR (rs12826786, rs920778, and rs1899663) polymorphisms and CRC risk in the Saudi population by genotyping using a TaqMan genotyping assay in 144 CRC cases and 144 age- and sex-matched controls. We found a significant (p < 0.05) association between SNP rs920778 G > A and CRC risk, and a protective role of SNPs rs12826786 (C > T) and rs1899663 (C > A) was noticed. The homozygous mutant "AA" genotype at rs920778 (G > A) showed a significant correlation with the female sex and colon tumor site. The homozygous TT in SNP rs12816786 (C > T) showed a significant protective association in the male and homozygous AA of SNP rs1899663 (C > A) with colon tumor site. These results indicate that HOTAIR can be a powerful biomarker for predicting the risk of colorectal cancer in the Saudi population. The association between HOTAIR gene polymorphisms and the risk of CRC in the Saudi population was reported for the first time here.

Expression and Polymorphism of TSLP/TSLP Receptors as Potential Diagnostic Markers of Colorectal Cancer Progression.

Colorectal cancer (CRC) is the third most common malignancy and the fourth leading cause of cancer-related mortality worldwide. Inflammation is considered as a critical driver for CRC development and growth. We investigated the association between polymorphisms/expression levels of thymic stromal lymphopoietin (TSLP) /TSLP receptors and CRC risk in Saudi population. DNA samples were isolated from blood samples from 220 participants. Case subjects were 112 patients diagnosed with CRC, while control subjects were 108 healthy individuals, who were not diagnosed with any type of malignancy. We selected two single nucleotide polymorphisms (SNPs) located in the thymic stromal lymphopoietin gene (rs10043985 and rs2289276), three SNPs in TSLP receptor gene (TSLPR; rs36139698, rs36177645, and rs36133495), and two other SNPs in interleukin-7 receptor gene (IL-7R; rs12516866 and rs1053496), and designated these SNPs for a case-control genotyping study. The gene expression was analyzed using quantitative RT-PCR and immunohistochemistry assays array on 20 matching colorectal cancer/normal tissues. mRNA expressions and protein levels of TSLP, TSLPR-α subunit, and IL-7R-α subunit showed a 4-fold increase in colon cancer tissues when compared to normal colon tissues. Furthermore, two SNPs (rs10043985 of TSLP and rs1053496 of IL-7R) showed statistically significant correlations with CRC susceptibility. Interestingly, only rs10043985 showed a statistically significant association (p < 0.0001) in the genotypic and phenotypic levels with CRC for all clinical parameters (age, gender, and tumor location) tested. However, IL-7R rs1053496 genotyping results presented a significant correlation (p < 0.05) in male CRC patients and in individuals under 57 years of age. TSLP rs2289276, IL-7R rs12516866, and all TSLPR variants did not display any significant genotypic or phenotypic correlations in all tested clinical parameters. This study identified that TSLP rs10043985 and IL-7R rs1053496 SNPs, and the expression levels of TSLP and TSLPR-α subunit, can be used as markers for CRC development and treatment. However, additional investigations are required on larger group of patients from diverse ethnicities to confirm the genetic association of these variants to CRC.

Correlation between genetic variation in thymine DNA glycosylase and smoking behavior.

Cigarette smoking is a major lifestyle factor leading to different human diseases. The DNA repair gene, thymine DNA glycosylase, is important to cell survival because it stops cells from becoming cancerous protecting/preventing DNA. Exposure to CS may induce genetic changes such as single nucleotide polymorphisms in DNA repair genes. Therefore, the purpose of this study was to investigate the genotype and allele distributions of four TDG SNPs with only smoking behavior in normal patients. Four TDG SNPs-rs4135066 (C/T), rs3751209 (A/G), rs1866074 (C/T), and rs1882018 (C/T) were analyzed by genotyping 235 and 239 blood samples collected from cigarette smokers and non-smokers, among the Saudi population. The results showed that TDG rs4135066 has a significant susceptibility effect observed in long-term smokers (>5 years; OR = 4.53; P = 0.0347) but not in short-term smokers (≤5 years) in contrast with non-smokers. Also, in smokers aged less than 29 years, the "CT," "TT," and "CT + TT" alleles of rs1882018 increased the risk of developing all diseases related to smoking by approximately 6, 4, and 5 times, respectively, in contrast with the ancestral "CC" homozygous allele. A comparison of the allele distributions of TDG SNPs in a Saudi population with those in other populations represented in the HapMap project showed that the genetic makeup of the Saudi Arabian population appears to differ from that of other ethnicities. Exceptions include the Yoruba people in Ibadan, Nigeria; those of Mexican ancestry in Los Angeles, California; the Luhya population in Webuye, Kenya; Gujarati Indians in Houston, Texas; and the Tuscan population in Italy, which showed similar allelic frequencies for rs3751209 compared to our Saudi population. In this ethnic, we have found a high variation in the distribution of the alleles and genotype frequencies on TDG gene. This variation on TDG SNP's with smoking could lead to increase the susceptibility to many diseases related to smoking habits in this population.

TSLP and TSLP receptors variants are associated with smoking.

BACKGROUND: To search for new prevention markers for early detection of the diseases caused by tobacco, we aimed to investigate the polymorphisms in TSLP and TSLPRs associated with cigarette smoking in the Saudi population. MATERIALS AND METHODS: Samples were collected from 177 smokers and 126 healthy controls. Three TSLP SNPs [rs3806933, rs2289276, and rs10043985], three TSLPR SNPs [rs36133495, rs36177645, and rs36139698], and two IL7R SNPs rs1053496 and rs12516866 were analyzed by genotyping. RESULTS: Two TSLP SNPs (rs10043985 and rs3806933) and one TSLPR SNP (rs36139698) showed significant correlations with smoking behavior, but not IL7R rs12516866 and rs1053496. rs10043985 showed a clear association with long-term smoking regardless of daily cigarette consumption. rs2289276 was associated with short-term smoking but not with daily cigarette consumption. rs3806933 was highly associated with different smoker subgroups. Rs36139698 was highly associated with long-term smokers who consumed ≥20 cigarettes/day, and the "T" allele was associated only with individuals who smoked ≤20 cigarettes/day. Rs36139698 corresponds to a P195L substitution and produces a TSLPR mutant with a predicted ΔΔG increase of 2.15 kcal/mol and has a more stable structure than the wild-type variant. CONCLUSIONS: Investigating TSLP and TSLPR polymorphisms is crucial for elucidating the mechanisms underlying tobacco-induced diseases.

TDG Gene Polymorphisms and Their Possible Association with Colorectal Cancer: A Case Control Study.

Genetic alterations that might lead to colorectal cancer involve essential genes including those involved in DNA repair, inclusive of base excision repair (BER). Thymine DNA glycosylase (TDG) is one of the most well characterized BER genes that catalyzes the removal of thymine moieties from G/T mismatches and is also involved in many cellular functions, such as the regulation of gene expression, transcriptional coactivation, and the control of epigenetic DNA modification. Mutation of the TDG gene is implicated in carcinogenesis. In the present study, we aimed to investigate the association between TDG gene polymorphisms and their involvement in colon cancer susceptibility. One hundred blood samples were obtained from colorectal cancer patients and healthy controls for the genotyping of seven SNPs in the TDG gene. DNA was extracted from the blood, and the polymorphic sites (SNPs) rs4135113, rs4135050, rs4135066, rs3751209, rs1866074, and rs1882018 were investigated using TaqMan genotyping. One of the six TDG SNPs was associated with an increased risk of colon cancer. The AA genotype of the TDG SNP rs4135113 increased the risk of colon cancer development by more than 3.6-fold, whereas the minor allele A increased the risk by 1.6-fold. It also showed a 5-fold higher risk in patients over the age of 57. SNP rs1866074 showed a significant protective association in CRC patients. The GA genotype of TDG rs3751209 was associated with a decreased risk in males. There is a significant relationship between TDG gene function and colorectal cancer progression.

Expression and allele frequencies of Thymic stromal lymphopoietin are a key factor of breast cancer risk.

BACKGROUND: Thymic stromal Lymphopoeitin (TSLP) is a key cytokine involved in inflammation and cancer progression. TSLP gene polymorphisms have been associated with increased susceptibility to cancer progression in different organs. We performed a control case study to examine the correlation of expression and polymorphisms of three nucleotides in TSLP with breast cancer (BC) risk in Saudi Arabian females. MATERIALS AND METHODS: The study was conducted on 116 healthy control subjects and 127 female patients with BC for the purpose of genotyping. Ten matching tissues provided data on immunohistochemistry to evaluate TSLP expression. Three SNPs (rs10043985, rs2289276, and rs3806933) were genotyped with TaqMan allelic discrimination assay. The patients' ages and estrogen receptor statuses were used to investigate the potential correlations between the different variations of TSLP genotypes and BC risk. RESULTS: BC tissues expressed positive immuno-staining for TSLP at a high rate compared to normal matching breast tissues. Malignant breast tumors exhibited higher TSLP expression than benign breast tumors. We also found that the rs3806933 (T) allele frequency decreased the risk of developing BC in the study population (OR = 0.356, p = 0.00027) significantly (0.356 times). Interestingly, statistical analysis revealed that the genotype mutant (AC) and the allele mutant (C) of rs10043985 within TSLP were significantly correlated with an increased BC risk (odds ratio [OR] = 4.762, confidence interval [CI] = 1.000-22.666, p = 0.03244; OR = 4.762, CI = 1.000-22.666, p = 0.03244; and OR = 4.575, CI = 0.975-21.464, p = 0.03516, respectively). In addition, the AC and AC + CC genotypes of TSLP rs10043985 were confirmed to be associated with an increased risk of BC risk in women aged above 48 years, compared with the AA genotype (AC and AC + CC vs. AA: OR = 9.468, CI = 0.493-181.768, p = 0.04537). CONCLUSION: The results reveal significant correlation between SNPs in TSLP and BC progression in Saudi Arabian female patients.

Novel sequence variants in the TLR6 gene associated with advanced breast cancer risk in the Saudi Arabian population.

Herein, we evaluated the association of the Toll-like receptor 6 (TLR6) single nucleotide polymorphisms (SNPs) rs3796508 (Val327Met) and rs5743810 (Ser249Pro) with breast cancer (BC) susceptibility in Saudi Arabian women, using in silico analysis. We found no significant differences in genotypic and allelic frequencies for rs3796508 between the BC patients (n = 127) and healthy individuals (n = 116). However, 86% of the BC patients, versus 98% of the healthy controls, carried the rs5743810 Pro allele (OR = 0.103, CI = 0.036-0.293, P = 0.00001). Advanced analysis based on the comparison of the estrogen receptor (ER)-positive and -negative patients with the healthy controls indicated a significant association between rs5743810 allelic frequency and BC risk protection (OR = 0.100, CI = 0.034-0.297, P = 0.00001 for ER+ BC cases; OR = 0.102, CI = 0.033-0.318, P = 0.00001 for ER-BC cases). Furthermore, rs5743810 was associated with BC risk protection at either above or below 48 years of age at diagnosis (OR = 0.101, CI = 0.022-0.455, P = 0.00037 for age ≤48 years; OR = 0.120, CI = 0.028-0.519, P = 0.00087 for age >48 years). Such associations were not found for rs3796508. In silico analysis indicated that these SNPs had neutral effects within the TLR6 structure, confirming the protective role of rs5743810. Our findings therefore suggest a strong association between rs5743810 and protection against BC risk in Saudi Arabian women. Importantly, the rs5743810 Pro allele could be a potential BC diagnostic biomarker in this ethnic population.

The Effect of Poly(ADP-ribose) Polymerase-1 Gene 3'Untranslated Region Polymorphism in Colorectal Cancer Risk among Saudi Cohort.

Background. DNA repair systems are essential for each cell to repair and maintain the genome integrity. Base excision repair pathway is one of the crucial pathways to maintain genome integrity and PARP-1 plays a key role in BER pathway. The purpose of this study is to evaluate the association between polymorphisms in PARP-1 3'untranslated region (3'UTR) SNP rs8679 and its expression in colorectal cancer. Methods. Genotyping and gene expression were performed using TaqMan assays. The effects of age, gender, and tumor location were evaluated in cases and controls regarding the genotyping results. Resulting data was analyzed using SPSS software. Results and Conclusions. Genotyping analysis for SNP rs8679 showed decreased susceptibility to colorectal cancer at heterozygous TC allele and at minor allele C. Further this protective association was also observed in younger age patients (≤57), in female patients, and also in patients with tumors located at colon and rectum. PARP-1 expression levels are significantly different in colorectal cancer compared to matched normal tissue. Our findings proved that the upregulation of PARP-1 is associated with tumor progression and poor prognosis in Saudi patients with colorectal cancer, suggesting that PARP-1 can be novel and valuable signatures for predicting the clinical outcome of patients with colorectal cancer.

Polymorphisms in DNA Repair Gene XRCC3 and Susceptibility to Breast Cancer in Saudi Females.

We investigated three common polymorphisms (SNPs) in the XRCC3 gene (rs861539, rs1799794, and rs1799796) in 143 Saudi females suffering from breast cancer (median age = 51.4 years) and 145 age matched normal healthy controls. DNA was extracted from whole blood and genotyping was conducted using PCR-RFLP. rs1799794 showed significant association, where AA and AA+AG occurred at a significantly higher frequency in the cancer patients compared to the control group (OR: 28.1; 95% CI: 3.76-21.12; χ (2): 22.82; p < 0.0001). The G allele was protective and presented with a dominant model. The genotype and allele frequencies of rs861539 C>T and rs1799796 A>G did not show a significant difference when the results in the patients and controls were compared. However, the frequency of rs1799796 differed significantly in patients with different age of diagnosis, tumor grade, and ER and HER2 status. The wild type A allele occurred at a higher frequency in the ER- and HER2- group. Our results among Saudis suggest that some variations in XRCC3 may contribute to breast cancer susceptibility. In conclusion, the results obtained during this study suggest that rs1799794 in XRCC3 shows strong association with breast cancer development in Saudi females.

Expression and Polymorphism of Toll-Like Receptor 4 and Effect on NF-κB Mediated Inflammation in Colon Cancer Patients.

Our aim was to evaluate the association between the expression and the polymorphism of TLR4/NF-κB pathways and colon cancer. TLR4 (rs4986790, rs10759932, rs10759931 and rs2770150) were genotyped in blood samples from Colorectal patients and healthy controls. TLR4 and cytokines inflammatory expression were evaluated by real time PCR on 40 matching normal and colon tissues and the protein level by Immunohistochemistry. The high level of TLR4 expression in colon cancer tissues is mainly due to infections by bacteria in the human colon and leads to induction of an acute secretion of inflammatory cytokines mediated by NF-κB. Also, we report here a clear evidence for an association between TLR4 rs10759931 polymorphism (OR = 0.086, CI: 0.04-0.18, P = <0.00001). This polymorphism affects the entire population without being specific to either gender or to any age group. In contrast, the rs2770150 is associated with colon cancer in women aged over 50 years and is closely linked with the decreased levels of female sex hormones during the post-menopausal period (OR = 0.188, CI: 0.074-0.48, P = <0.00084). rs10759932 and rs4986790 appear to have any association with colon cancer. Our data suggest that TLR4 SNPs could possibly serve as biomarkers for decision making in colon cancer treatment.

Novel hypoxanthine guanine phosphoribosyltransferase gene mutations in Saudi Arabian hyperuricemia patients.

Over the past decade, a steady increase in the incidence of HPRT-related hyperuricemia (HRH) has been observed in Saudi Arabia. We examined all the nine exons of HPRT gene for mutations in ten biochemically confirmed hyperuricemia patients, including one female and three normal controls. In all, we identified 13 novel mutations in Saudi Arabian HPRT-related hyperuricemia patients manifesting different levels of uric acid. The Lys103Met alteration was highly recurrent and was observed in 50% of the cases, while Ala160Thr and Lys158Asn substitutions were found in two patients. Moreover, in 70% of the patients ≥2 mutations were detected concurrently in the HPRT gene. Interestingly, one of the patients that harbored Lys103Met substitution along with two frameshift mutations at codons 85 and 160 resulting in shortened protein demonstrated unusually high serum uric acid level of 738 µmol/L. Two of the seven point mutations that resulted in amino acid change (Lys103Met and Val160Gly) were predicted to be damaging by SIFT and Polyphen and were further analyzed for their protein stability and function by molecular dynamics simulation. The identified novel mutations in the HPRT gene may prove useful in the prenatal diagnosis and genetic counseling.