Biomedical subjects

Zhengdong Zhang

Publications and source records attributed to Zhengdong Zhang.

At least 19 recordsLinked to original sources

PubMed2024

Genetic variants reduced POPs-related colorectal cancer risk via altering miRNA binding affinity and m6A modification.

Exposure to persistent organic pollutants (POPs) may contribute to colorectal cancer risk, but the underlying mechanisms of crucial POPs exposure remain unclear. Hence, we systematically investigated the associations among POPs exposure, genetics and epigenetics and their effects on colorectal cancer. A case-control study was conducted in the Chinese population for detecting POPs levels. We measured the concentrations of 24 POPs in the plasma using gas chromatography-tandem mass spectrometry (GC-MS/MS) and evaluated the clinical significance of POPs by calculating the area under the receiver operating characteristic curve (AUC). To assess the associations between candidate genetic variants and colorectal cancer risk, unconditional logistic regression was used. Compared with healthy control individuals, individuals with colorectal cancer exhibited higher concentrations of the majority of POPs. Exposure to PCB153 was positively associated with colorectal cancer risk, and PCB153 demonstrated superior accuracy (AUC=0.72) for predicting colorectal cancer compared to other analytes. On PCB153-related genes, the rs67734009 C allele was significantly associated with reduced colorectal cancer risk and lower plasma levels of PCB153. Moreover, rs67734009 exhibited an expression quantitative trait locus (eQTL) effect on ESR1, of which the expression level was negatively related to PCB153 concentration. Mechanistically, the risk allele of rs67734009 increased ESR1 expression via miR-3492 binding and m6A modification. Collectively, this study sheds light on potential genetic and epigenetic mechanisms linking PCB153 exposure and colorectal cancer risk, thereby providing insight into the accurate protection against POPs exposure.

Humans↗

PubMed2006

Genetic variants of the vitamin D receptor gene alter risk of cutaneous melanoma.

Sunlight causes DNA damage but also induces production of vitamin D whose metabolite 1,25-(OH)2D3 has antiproliferative and pro-differentiative effects in both melanocytes and cutaneous melanoma (CM) cells mediated through the vitamin D receptor (VDR). We hypothesized that genetic polymorphisms of VDR are associated with risk of CM. In a hospital-based case-control study of 602 non-Hispanic white CM patients and 603 cancer-free control subjects frequency matched by age and sex, we genotyped two VDR polymorphisms (TaqI and FokI) and assessed their association with CM risk. We found that a significantly decreased risk was associated with VDR-TaqI Tt (adjusted odds ratio (OR), 0.70; 95% confidence interval (CI), 0.54-0.90) and Tt+tt (OR=0.70; 95% CI, 0.55-0.89) genotypes, compared with the VDR-TaqI TT genotype, whereas an increased risk was associated with VDR-FokI Ff genotype (OR=1.32; 95% CI, 1.03-1.68), and a borderline significantly increased risk was associated with Ff+ff (OR=1.26; 95% CI, 1.00-1.59) genotypes, compared with the VDR-FokI FF genotype. In conclusion, genetic variants (i.e., TaqI t protective allele and FokI f risk allele) in VDR may alter risk of CM.

Alleles↗

PubMed2006

Polymorphisms of FAS and FAS ligand genes involved in the death pathway and risk and progression of squamous cell carcinoma of the head and neck.

PURPOSE: Alteration of the FAS/FAS ligand (FASLG) pathway regulating cell death may lead to cancer development, but the effects of functional promoter polymorphisms of the FAS and FASLG genes on risk of squamous cell carcinoma of the head and neck (SCCHN) are unknown. DESIGN: We genotyped the FAS -1377 G>A, FAS -670 A>G, FASLG -844 C>T, and FASLG IVS2nt -124 A>G polymorphisms in 721 case patients with SCCHN and 1,234 cancer-free non-Hispanic White control subjects frequency-matched by age and sex. Multivariate logistic regression was used to assess the adjusted odds ratios (OR) and 95% confidence intervals (CI). RESULTS: Compared with the FAS -1377 GG and -670 AA genotypes, the FAS -1377 AA and -670 (GG+AG) genotypes were associated with an increased risk of SCCHN (OR, 2.23; 95% CI, 1.07-4.64 and OR, 1.24; 95% CI, 1.01-1.52, respectively), whereas no risk of SCCHN was associated with any of the FASLG genotypes. When we used the combined FAS -1377 (GG+AG)/-670 AA genotypes as the reference, we found that the individuals carrying the FAS -1377 AA/-670 (GG+AG) had the highest risk (OR, 2.69; 95% CI, 1.24-5.83), whereas individuals carrying genotypes other than FAS -1377 (GG+AG)/-670 AA had a higher risk of SCCHN (OR, 1.24; 95% CI, 1.01-1.52). Furthermore, the elevated risk was particularly evident for pharyngeal cancer with the larger tumors without regional lymph metastasis (OR, 1.77; 95% CI, 1.07-2.94). CONCLUSIONS: The FAS (but not FASLG) polymorphisms seem to contribute to risk of developing SCCHN, particularly the pharyngeal cancer in non-Hispanic Whites. However, potential selection bias warrants future population-based studies to verify the findings.

Adolescent↗

PubMed2006

Low concentrations mono-butyl phthalate stimulates steroidogenesis by facilitating steroidogenic acute regulatory protein expression in mouse Leydig tumor cells (MLTC-1).

Di-n-butyl phthalate (DBP) is one of the most dominant phthalate esters and is widely distributed environmental contaminant. Although previous studies have demonstrated that DBP led to a variety of male reproductive abnormalities similar to those caused by androgen receptor antagonists, DBP and its active metabolite, mono-butyl phthalate (MBP), have been demonstrated no affinity for the androgen receptor, but rather exert anti-androgenic effect by altering testosterone biosynthesis. Furthermore, all these results were obtained from very high administrations of DBP or MBP. The purpose of this study was to determine the onset and the site of action of relatively low concentration of MBP on steroidogenesis in vitro. The mouse Leydig tumor cells (MLTC-1) was employed as a cellular model to investigate the effect of MBP on steroidogenesis. Various concentrations of MBP (1, 10, 100 and 1000nmol/l) and its solvent dimethyl sulfoxide (DMSO) were added to the medium for 24h followed by stimulation of some compounds such as human chorionic gonadotrophin (hCG), cholera toxin (CT), forskolin, cAMP analog 8-Br-cAMP, 22(R)-hydroxycholesterol (22R-HC) and pregnenolone. Progesterone in the medium and amounts of intracellular cAMP were measured by RIA. Expression of steroidogenic acute regulatory protein (StAR) was monitored by real-time PCR and Western blotting. The results revealed that the increases of progesterone production in the presence of hCG, CT, forskolin and 8-Br-cAMP were augmented by MBP. In contrast, the levels of intracellular cAMP exhibited no statistical significance when MLTC-1 cells were treated as above. These results implied that the site in the steroid biosynthesis pathway affected by MBP occurs after PKA activation in MLTC-1 cells. Moreover, supplementing the medium with 22R-HC and pregnenolone as progesterone precursors for P450 side chain cleavage enzyme (P450scc) and 3beta-hydroxysteroid dehydrogenase (3beta-HSD), respectively, resulted in no rise in progesterone production, making clear that MBP did not influence the P450scc and 3beta-HSD but on the rate-limiting step, cholesterol transportation into mitochondria. In fact, the above results were confirmed by the upgraded StAR expression in MBP-treated cells. These data support that MBP promotes steroid hormone production by facilitating StAR expression in MLTC-1 cells.

17-Hydroxysteroid Dehydrogenases↗

PubMed2006

MDM2 gene promoter polymorphisms and risk of lung cancer: a case-control analysis.

The MDM2 protein negatively regulates p53 expression level in modulating DNA repair, cell-cycle control, cell growth and apoptosis. Polymorphisms in the promoter region of the MDM2 gene have been shown to alter protein expression and may, thus, play a role in carcinogenesis. To test our hypothesis that the MDM2 promoter polymorphisms are associated with risk of lung cancer, we conducted a hospital-based, case-control study of 1026 non-Hispanic white patients newly diagnosed with lung cancer and 1145 cancer-free controls who were frequency-matched by age (+/-5 years), sex, ethnicity and smoking status. We genotyped for the MDM2 promoter G2580T (also called SNP309) and G2164A polymorphisms that have a minor allele frequency >0.05. The distributions of the MDM2-2580G variant allele and genotypes were significantly less common among the cases than among the controls (P = 0.038 and 0.045, respectively), but this was not evident for MDM2-2164G (P = 0.865 and 0.614, respectively). Compared with the MDM2-2580TT genotype, the MDM2-2580G variant genotypes were associated with a decreased risk of lung cancer [odds ratio = 0.81 and 95% confidence interval = 0.67-0.98 for GT, 0.83 (0.63-1.08) for GG, and 0.81 (0.68-0.97) for the combined GT/GG genotype]. However, no significant association was observed between the MDM2-2164G variant genotypes and lung cancer risk. Our results suggest that the MDM2-2580G allele may be a marker of reduced genetic susceptibility to lung cancer in the non-Hispanic white population, a finding that seems to contradict previous reports.

Adult↗

PubMed2006

The DNA sequence, annotation and analysis of human chromosome 3.

After the completion of a draft human genome sequence, the International Human Genome Sequencing Consortium has proceeded to finish and annotate each of the 24 chromosomes comprising the human genome. Here we describe the sequencing and analysis of human chromosome 3, one of the largest human chromosomes. Chromosome 3 comprises just four contigs, one of which currently represents the longest unbroken stretch of finished DNA sequence known so far. The chromosome is remarkable in having the lowest rate of segmental duplication in the genome. It also includes a chemokine receptor gene cluster as well as numerous loci involved in multiple human cancers such as the gene encoding FHIT, which contains the most common constitutive fragile site in the genome, FRA3B. Using genomic sequence from chimpanzee and rhesus macaque, we were able to characterize the breakpoints defining a large pericentric inversion that occurred some time after the split of Homininae from Ponginae, and propose an evolutionary history of the inversion.

Animals↗

PubMed2006

The finished DNA sequence of human chromosome 12.

Human chromosome 12 contains more than 1,400 coding genes and 487 loci that have been directly implicated in human disease. The q arm of chromosome 12 contains one of the largest blocks of linkage disequilibrium found in the human genome. Here we present the finished sequence of human chromosome 12, which has been finished to high quality and spans approximately 132 megabases, representing approximately 4.5% of the human genome. Alignment of the human chromosome 12 sequence across vertebrates reveals the origin of individual segments in chicken, and a unique history of rearrangement through rodent and primate lineages. The rate of base substitutions in recent evolutionary history shows an overall slowing in hominids compared with primates and rodents.

Animals↗

PubMed2006

Microbial identification by mass cataloging.

BACKGROUND: The public availability of over 180,000 bacterial 16S ribosomal RNA (rRNA) sequences has facilitated microbial identification and classification using hybridization and other molecular approaches. In their usual format, such assays are based on the presence of unique subsequences in the target RNA and require a prior knowledge of what organisms are likely to be in a sample. They are thus limited in generality when analyzing an unknown sample.Herein, we demonstrate the utility of catalogs of masses to characterize the bacterial 16S rRNA(s) in any sample. Sample nucleic acids are digested with a nuclease of known specificity and the products characterized using mass spectrometry. The resulting catalogs of masses can subsequently be compared to the masses known to occur in previously-sequenced 16S rRNAs allowing organism identification. Alternatively, if the organism is not in the existing database, it will still be possible to determine its genetic affinity relative to the known organisms. RESULTS: Ribonuclease T1 and ribonuclease A digestion patterns were calculated for 1,921 complete 16S rRNAs. Oligoribonucleotides generated by RNase T1 of length 9 and longer produce sufficient diversity of masses to be informative. In addition, individual fragments or combinations thereof can be used to recognize the presence of specific organisms in a complex sample. In this regard, 140 strains out of 1,921 organisms (7.3%) could be identified by the presence of a unique RNase T1-generated oligoribonucleotide mass. Combinations of just two and three oligoribonucleotide masses allowed 54% and 72% of the specific strains to be identified, respectively. An initial algorithm for recovering likely organisms present in complex samples is also described. CONCLUSION: The use of catalogs of compositions (masses) of characteristic oligoribonucleotides for microbial identification appears extremely promising. RNase T1 is more useful than ribonuclease A in generating characteristic masses, though RNase A produces oligomers which are more readily distinguished due to the large mass difference between A and G. Identification of multiple species in mixtures is also feasible. Practical applicability of the method depends on high performance mass spectrometric determination, and/or use of methods that increase the one dalton (Da) mass difference between uracil and cytosine.

Algorithms↗

PubMed2006

Carbaryl inhibits basal and FSH-induced progesterone biosynthesis of primary human granulosa-lutein cells.

Carbaryl is known to impede female reproductive function, however, the mechanisms through which the adverse effects are mediated are not clearly elucidated. In order to get insight into the mechanisms, this study was conducted to raise fresh concerns about the potential effects of carbaryl on steroidogenesis by primary human granulosa-lutein cells (hGLCs) and explore the possible nature of this action. hGLCs were co-incubated with various concentrations of carbaryl at 0, 1, 5, 25, 125 micromol/L for 24 h to examine effects of this carbamate pesticide on progesterone accumulation. We observed that the carbaryl inhibited basal and FSH-induced progesterone production in a dose-dependent manner. We also investigated the effects of carbaryl on 22(R)-hydroxycholesterol (22R-HC)-stimulated progesterone yield, basal and FSH-stimulated StAR gene expression and cyclic adenosine monophosphate (cAMP) production, as well as forskolin (non-specific activator of adenylyl cyclase)-induced progesterone and cAMP production of hGLCs. We found that the decreased progesterone biosynthesis was accompanied with a reduced cAMP abundance on both basal and FSH-induced condition. Furthermore, our results demonstrated that the 22R-HC could remove the carbaryl-induced restraint of progesterone biosynthesis, suggesting that carbaryl caused a disruption of cholesterol transport across mitochondrial membranes, which was further confirmed by the observation that carbaryl inhibited the gene expression of steroidogenic acute regulatory protein (StAR). In addition, the inhibitory effects of carbaryl on progesterone and cAMP production were completely reversed by addition of forskolin to the cell culture, which indicated a repaired site on the upstream components of adenylate cyclase or adenylate cyclase per se by carbaryl in the cAMP-mediated signal pathway. All the effects mentioned above were not due to a detrimental action of carbaryl on cell viability by MTS assay. In conclusion, carbaryl may inhibit steroidogenesis, at least in part, by obstructing the delivery of cholesterol over mitochondrial membranes and attenuating cAMP generation.

Carbaryl↗

PubMed2006

Functional polymorphisms in the promoter regions of the FAS and FAS ligand genes and risk of bladder cancer in south China: a case-control analysis.

BACKGROUND: FAS and FASLG together initiate apoptosis, which prevents tumor development. FAS and FASLG polymorphisms in the promoter regions can alter the transcriptional activities and thus alter risk of cancer. We hypothesized that the FAS -1377G>A, -670A>G, and FASLG -844T>C polymorphisms are associated with risk of bladder cancer. METHODS: In a hospital-based case-control study of 216 case patients with newly diagnosed bladder transitional cell carcinoma and 252 cancer-free controls frequency-matched by age and sex, we genotyped polymorphisms using PCR-restriction fragment length polymorphism. RESULTS: We found a statistically significantly increased risk of bladder cancer associated with the FASLG -844CC genotype [adjusted OR=1.51; 95% CI 1.03-2.23] compared with -844 (CT+TT). Consistently, the FAS haplotype genotypes with 2-4 variant (risk) alleles (-1377A and -670A) were associated with an increased risk of bladder cancer compared to 0-1 variants (OR=2.14; 95% CI 1.10-4.16). Furthermore, when we evaluated these three polymorphisms together, we found that the combined genotypes with 4-6 variant (risk) alleles (-1377A, -670A, and -844C) were associated with an increased risk of bladder cancer (OR=1.58; 95% CI 1.07-2.34) compared to 1-3 variants, and this increased risk was more pronounced among subgroups of aged >50 years (OR=1.70; 95% CI 1.11-2.61) and smokers (OR=1.88; 95% CI 1.06-3.32). CONCLUSIONS: FAS and FASLG polymorphisms appear to jointly contribute to risk of bladder cancer in this southern Chinese population. Larger studies are needed to verify these findings.

Adult↗

PubMed2006

Polymorphisms of the FAS and FAS ligand genes associated with risk of cutaneous malignant melanoma.

The FAS/FAS ligand (FASLG) system has a key role in regulating cell growth and thus tumorigenesis. Functional promoter polymorphisms of the FAS and FASLG genes alter the transcriptional activities, but no published study has investigated the role of these polymorphisms in the etiology of cutaneous malignant melanoma (CMM). In a hospital-based, case-control study of 602 non-Hispanic white CMM patients and 603 cancer-free age- and sex-matched control subjects, we genotyped FAS-1377G>A, FAS-670A>G, FASLG-844T>C and FASLG-IVS2nt-124G>A polymorphisms and assessed their respective associations with CMM risk. We found that an increased risk of CMM was associated with the FAS-1377GG [adjusted odds ratio (OR)=1.32; 95% confidence interval (CI)=1.00-1.75 for -1377GG] and -670AA (adjusted OR=1.28; 95% CI=1.00-1.65 for -670AA) genotypes compared to the -1377AA/AG and -670AG/GG genotypes, respectively; an increased risk of CMM was associated with the FASLG-IVS2nt-124AG+GG (OR=1.54; 95% CI=1.18-2.01) genotype compared to the AA genotype, but no evident risk was associated with any of the FAS-844T>C genotypes. In the combined analysis of these four variant alleles, we found that, compared to those having 0-3 variants, those having 4-8 variant alleles had a significantly increased risk for CMM (OR=1.38; 95% CI=1.10-1.73), and this risk was more pronounced in subgroups of old (>50 years) males, and those who were at low risk of sunlight-induced CMM, except for having fair skin colour, moles, dysplastic nevi and a family history of cancer. In conclusion, genetic variants in the FAS and FASLG genes may contribute to the etiology of CMM in the general population, particularly in those with a low risk of sunlight-induced CMM.

Alleles↗

PubMed2006

Association of genetic variants of O6-methylguanine-DNA methyltransferase with risk of lung cancer in non-Hispanic Whites.

O6-methylguanine, a methylated damage lesion in DNA, correlates with spontaneous G:C --> A:T transition mutations and leads to activation of oncogene K-ras or dysfunction of the tumor suppressor gene p53. O6-methylguanine-DNA methyltransferase (MGMT) is critical for repairing damage to the O6-position of guanine. Therefore, we tested our hypothesis that genetic variants of MGMT are associated with increased lung cancer risk in a Caucasian population of 1,121 lung cancer patients and 1,163 matched cancer-free controls. We genotyped four potentially functional single nucleotide polymorphisms (SNPs) of MGMT: exon 3 codon 84C --> T (L84F), exon 5 codon 143A --> G (I143V), and two promoter SNPs 135G --> T and 485C --> A. The allele frequency distributions of the SNPs of codon 84C --> T and the promoter 135G --> T in the cases were borderline different from that in the controls. After defining the minor allele (T for codon 84C --> T and G for codon 143A --> G) as the variant allele, we categorized the MGMT genotypes as either 0 variants (84CC-143AA) or 1-4 variants. Compared with 0 variants, those with 1-4 variants showed a statistically significantly increased risk of lung cancer (P = 0.040). Further stratification analysis showed that this increased risk was more pronounced in women, current smokers, and non-small cell lung cancer. We did not find any association between the MGMT promoter SNPs and lung cancer risk. Our findings suggest that non-synonymous SNPs in MGMT are associated with modestly increased risk of lung cancer in Caucasians and need to be further investigated.

Case-Control Studies↗

PubMed2005

Exon 3 polymorphisms and haplotypes of O6-methylguanine-DNA methyltransferase and risk of bladder cancer in southern China: a case-control analysis.

Methylating agents are involved in bladder carcinogenesis. O6-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair protein that removes methyl group from O6-methylguanine and thus plays an important role in the etiology of cancer. We hypothesized that two MGMT polymorphisms in exon 3, C16195T (or MGMT L53L) and C16286T (or MGMT L84F) are associated with risk of bladder cancer. In a hospital-based case-control study of 167 patients with bladder cancer and 204 cancer-free controls frequency-matched by age, sex, smoking status, and alcohol use, we genotyped these two MGMT polymorphisms. We found that these two polymorphisms alone had a non-significant main effect on risk of bladder cancer. However, when these two polymorphisms were evaluated together, individuals with the combined genotypes or haplotypes with one or more variant alleles (i.e. the 16195T and 16286T alleles) had statistically significantly increased risk of bladder cancer (adjusted odd ratio [OR]=1.67, 95% confidence interval [CI], 1.01-2.77) compared with those with no variant allele. In the stratification analysis, the risk of bladder cancer was increased in a dose-response manner as the age increased (P(trend)=0.010), and the increased risk was more pronounced among old subjects (>65 years) (adjusted OR=2.51, 95% CI, 1.05-6.04), men (1.76, 1.00-3.10), and non-drinkers (1.91, 1.08-3.36). In conclusion, these two MGMT polymorphisms may jointly play a role, in the etiology of bladder cancer in southern Chinese population. Larger studies are warranted to validate our findings.

Adult↗

PubMed2005

Overexpression of S100A2 protein as a prognostic marker for patients with stage I non small cell lung cancer.

S100A2, a calcium-binding protein, recently became of major interest because of its differential expression during transformation and metastasis in various tumors. The purpose of this study was to investigate the prognostic significance of S100A2 expression in the early-stage non small lung cancer (NSCLC). Immunohistochemical analysis to determine the percentage of cells staining positive for S100A2 was performed on 11 NSCLC tissue microarray slides containing samples from 113 patients with pathologic stage I NSCLC who had undergone curative surgery. S100A2 was expressed in samples from 79 patients (69.9%). Kaplan-Meier analysis showed that patients whose tumors had positive S100A2 expression had a significantly lower overall survival and disease-specific survival rate at 5 years after surgery than did patients with negative S100A2 expression (p < 0.001 and p < 0.001, respectively). Age at diagnosis, histologic type of cancer, degree of differentiation and smoking history did not have a statistically significant effect on survival. Multivariate analysis confirmed that S100A2 expression is a better predictor for disease-specific survival than were other clinical and histologic variables tested. Our results suggested that the expression of the S100A2 protein in stage I NSCLC indicates poor prognosis and may be used to identify patients with early-stage NSCLC who might benefit from adjuvant treatment.

Aged↗

PubMed2005

Polymorphisms of thymidylate synthase in the 5'- and 3'-untranslated regions associated with risk of gastric cancer in South China: a case-control analysis.

Fruits and certain vegetables have a protective effect on gastric cancer (GC) and folate is one of the nutrients in fruits and vegetables. We hypothesized that the polymorphisms of thymidylate synthase (TYMS) gene involved in folate metabolism are associated with GC risk. In a population-based case-control study of 337 GC cases and 326 controls, frequency-matched by age, sex and residential areas in a southern Chinese population, we genotyped the 28 bp tandem repeat in the TYMS 5'-untranslated enhanced region (TSER) and the 6 bp deletion/insertion at bp 1494 in the TYMS 3'-untranslated region (TS3'UTR). We found that although the TSER polymorphism had no main effect on GC risk, the TS3'UTR 6 bp/6 bp genotype was associated with a significantly increased risk of GC [adjusted odds ratio (OR) = 1.96, 95% confidence interval (CI) = 1.18-3.25], especially the non-cardiac gastric cancer (2.16, 1.22-3.82), compared with the 0 bp/0 bp genotype. However, when we evaluated these two polymorphisms together and used the combined genotype with zero variant allele (TSER 2R and TS3'UTR 6 bp variant alleles) as the reference, we found that the combined genotype with three or four variant alleles was associated with a significantly increased risk of GC (2.06, 1.12-3.79), especially the non-cardiac gastric cancer (2.33, 1.19-4.59), and this significant association was more pronounced among older women (>60 years old), non-smokers, and never tea drinkers. In conclusion, the TYMS polymorphisms, especially the TS3'UTR polymorphism, are associated with GC risk, especially the non-cardiac gastric cancer, and the TSER 2R and TS3'UTR 6 bp alleles may jointly play a role in the etiology of GC in the southern Chinese population. Larger studies are warranted to verify these findings.

3' Untranslated Regions↗

PubMed2005

Polymorphisms and haplotypes of serine hydroxymethyltransferase and risk of squamous cell carcinoma of the head and neck: a case-control analysis.

Low dietary intake of fruits and vegetables, particularly folate deficiency, has been associated with the risk of squamous cell carcinoma of the head and neck (SCCHN). We hypothesized that polymorphisms of the cytosolic serine hydroxymethyltransferase (SHMT1) gene involved in folate-dependent, one-carbon metabolism are associated with SCCHN risk. In a hospital-based, case-control study of 721 non-Hispanic white SCCHN patients and 1,234 control subjects, frequency-matched by age and sex, three known SHMT1 polymorphisms (34761C>T, 34840C>G and 34859C>T) were genotyped. It was found that none of these three polymorphisms alone had a significant main effect on the risk of SCCHN. However, when the three polymorphisms were evaluated together by the number of the variant (risk) haplotype alleles (i.e. 34761 T, 34840G or 34859 T), the risk of SCCHN was significantly increased in a dose-response manner as the number of variant haplotype alleles increased compared to those with zero variant alleles [adjusted odd ratio (OR)=1.39, 95% confidence interval (CI)=1.14-1.70 for 1-3 variant alleles and OR=1.46, 95% CI=1.09-1.97 for 4-6 variant alleles; Ptrend=0.001]. In stratification analysis, this significant association was confined to younger men (<or=64 years), ever smokers, ever drinkers and patients whose primary tumor site was in the pharynx or larynx. In conclusion, these three SHMT1 polymorphisms may play a joint role in the etiology of SCCHN in a non-Hispanic white population.

Aged↗

PubMed2005

Polymorphisms of methionine synthase and methionine synthase reductase and risk of lung cancer: a case-control analysis.

Although tobacco is the major lung cancer risk factor, folate deficiency has also been implicated as a risk. Methionine synthase (MS; gene symbol, MTR) and methionine synthase reductase (MSR; gene symbol, MTRR) play important roles in the folate metabolism pathway. It was hypothesized that polymorphisms of MTR and MTRR are associated with lung cancer risk and interact with dietary intake of folate-related nutrients in lung cancer etiology. In a hospital-based, case-control study of 1,035 lung cancer cases and 1,148 controls of non-Hispanic whites, frequency matched by age, sex, ethnicity and smoking status, the MTR 2756A>G and MTRR 66A>G polymorphisms were genotyped. It was found that the MTRRG allele was associated with a significantly increased lung cancer risk [adjusted odd ratio (OR)=1.34, 95% confidence interval (CI)=1.06-1.70 for the AG genotype and OR=1.39, 95% CI=1.08-1.78 for the GG genotype compared to the AA genotype]. Further analysis suggested some evidence of gene-diet interactions between the MTRR 66A>G polymorphism and dietary intake of total folate and vitamin B12. When the two polymorphisms were evaluated together by the number of the variant alleles (i.e. the MTR2756G and MTRR66A), lung cancer risk was significantly increased in a dose-dependent manner (Ptrend=0.045). The risk of lung cancer was 1.29 (0.98-1.69) for one variant allele, and 1.36 (1.04-1.77) for two or more variant alleles compared to the wild-type (0 variant allele) genotype. In conclusion, our data provide evidence supporting the association between the MTR 2756A>G and MTRR 66A>G polymorphisms and lung cancer risk, which may be modulated by dietary nutrient intake.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗

PubMed2005

Polymorphisms of vitamin D receptor gene protect against the risk of head and neck cancer.

Vitamin D has potent anti-tumour properties. Calcitriol [1,25(OH)2D3], the hormonal derivative of vitamin D3, is an antiproliferative and prodifferentiation factor for several cell types, including human squamous cells of the head and neck. Several polymorphisms of the vitamin D receptor (VDR) gene have been described, including a FokI restriction fragment-length polymorphism (RFLP) in exon 2 and an adjacent TaqI RFLP in exon 9. We hypothesized that the VDR FokI and TaqI polymorphisms are associated with the risk of developing squamous cell carcinoma of the head and neck (SCCHN). We conducted a hospital-based, case-control study of 719 SCCHN cases and 821 cancer-free controls (all non-Hispanic Whites) to assess the association between VDR polymorphisms and SCCHN risk. The cases and controls were frequency-matched on age, sex and ethnicity. Polymorphisms at the TaqI and FokI restriction sites were determined from genomic DNA by polymerase chain reaction-RFLP methods. Both homozygous variant genotypes (ff and tt) were associated with a decreased risk of SCCHN [odds ratio (OR)=0.72, 95% confidence interval (CI)=0.53-0.98 and OR=0.64, 95% CI=0.47-0.87, respectively] compared to the common FF and TT genotypes. The VDR variant genotypes were associated with a decreasing risk of SCCHN in a variant allele dose-dependent manner, and the decreasing trend in OR was statistically significant, particularly for the combined genotypes (Ptrend<0.001). These data suggest that the VDR f and t alleles and their genotypes may protect against SCCHN. However, further studies are warranted to confirm these findings.

Adult↗