G protein-mediated neuronal DNA fragmentation induced by familial Alzheimer's disease-associated mutants of APP.

Missense mutations in the 695-amino acid form of the amyloid precursor protein (APP695) cosegregate with disease phenotype in families with dominantly inherited Alzheimer's disease. These mutations convert valine at position 642 to isoleucine, phenylalanine, or glycine. Expression of these mutant proteins, but not of normal APP695, was shown to induce nucleosomal DNA fragmentation in neuronal cells. Induction of DNA fragmentation required the cytoplasmic domain of the mutants and appeared to be mediated by heterotrimeric guanosine triphosphate-binding proteins (G proteins).

Regulation of Cl- channels by multifunctional CaM kinase.

cAMP kinase has been shown to mediate the cAMP pathway for regulation of Cl- channels in lymphocytes, but the mediator of an alternative, Ca2+ pathway has not been identified. We show here that Ca2+ ionophore activates Cl- currents in cell-attached and whole-cell patch-clamp recordings of Jurkat T lymphocytes, but this activation is not direct. The effect of Ca2+ ionophore on whole-cell Cl- currents is inhibited by a specific peptide inhibitor of multifunctional Ca2+/calmodulin-dependent protein kinase (CaM kinase). Furthermore, Cl- channels are activated in excised patches by purified CaM kinase in a fashion that mimics the effect of Ca2+ ionophore in cell-attached recordings. These results suggest that CaM kinase mediates the Ca2+ pathway of Cl- channel activation.

Fatty acid synthase expression in squamous cell carcinoma of the tongue: clinicopathological findings.

BACKGROUND: Overexpression of fatty acid synthase (FAS), the cytosolic enzyme responsible for the conversion of dietary carbohydrates to fatty acids, has been reported in several human malignancies and pointed as a potential prognostic marker for some tumors. This study investigated whether FAS immunohistochemical expression is correlated with the clinicopathological characteristics of oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: The clinical features of 102 patients with OSCC of the tongue treated in a single institution were obtained from the medical records and all histopathological diagnoses were reviewed. The expression of FAS was determined by the standard immunoperoxidase technique in formalin-fixed and paraffin-embedded specimens and correlated with the clinicopathological characteristics of the tumors. RESULTS: Eighty-one cases (79.41%) were positive for FAS. Microscopic characteristics such as histological grade (P < 0.05), lymphatic permeation (P < 0.001), perineural infiltration (P < 0.05), and nodal metastasis (P < 0.02) were associated with FAS status. A significantly lower survival probability for patients with advanced clinical stage (log-rank test, P < 0.001), lymph nodes metastasis (log-rank test, P < 0.001), presence of vascular permeation (log-rank test, P = 0.05), and perineural invasion (log-rank test, P = 0.01) was observed in the studied samples. CONCLUSION: The expression of FAS in OSCC of the tongue is associated with the microscopic characteristics that determine disease progression and prognosis.

Head and neck mucosal melanoma: clinicopathological analysis of 51 cases treated in a single cancer centre and review of the literature.

Head and neck mucosal melanoma (HNMM) is a rare and aggressive malignancy. The objective of this study was to describe the outcomes of patients with HNMM. Clinical and pathological data from 51 patients with primary HNMM were reviewed. All patients were treated at a single cancer centre between 1954 and 2012. Most tumours involved the nasal cavity (35.3%) and upper gingiva (29.4%). The majority of lesions were ulcerated (54.9%) and pigmented (84.3%). Forty-three patients underwent surgical treatment and 21 (41.2%) underwent adjuvant chemotherapy and/or radiotherapy. Eight patients (15.7%) received palliative treatment. The median follow-up period was 21 months. During this period, 30 (58.8%) patients had tumour recurrences. At the last clinical evaluation, only seven (13.7%) patients were alive with no evidence of disease and three (5.9%) were alive with HNMM. There were significant differences in overall survival probability according to the presence of ulceration (P=0.004), metastatic lymph nodes (P=0.003), and treatment including a radical surgical procedure (P<0.001). On multivariate analysis, ulceration was the only variable associated with an increased risk of death. Despite the poor prognosis, there was significant improvement in overall survival in the most recent years in this sample, mainly due to advances in diagnosis and reconstruction techniques.

Neuronal apoptosis by apolipoprotein E4 through low-density lipoprotein receptor-related protein and heterotrimeric GTPases.

The epsilon4 genotype of apolipoprotein E (apoE4) is the most established predisposing factor in Alzheimer's disease (AD); however, it remains unclear how apoE4 contributes to the pathophysiology. Here, we report that the apoE4 protein (ApoE4) evokes apoptosis in neuronal cells through the low-density lipoprotein receptor-related protein (LRP) and heterotrimeric GTPases. We examined neuron/neuroblastoma hybrid F11 cells and found that these cells were killed by 30 microg/ml ApoE4, but not by 30 microg/ml ApoE3. ApoE4-induced death occurred with typical features for apoptosis in time- and dose-dependent manners, and was observed in SH-SY5Y neuroblastomas, but not in glioblastomas or non-neuronal Chinese hamster ovary cells. Activated, but not native, alpha2-macroglobulin suppressed this ApoE4 toxicity. Suppression by the antisense oligonucleotide to LRP and inhibition by low nanomolar concentrations of LRP-associated protein RAP provided evidence for the involvement of LRP. The involvement of heterotrimeric GTPases was demonstrated by the findings that (1) ApoE4-induced death was suppressed by pertussis toxin (PTX), but not by heat-inactivated PTX; and (2) transfection with PTX-resistant mutant cDNAs of Galpha(i) restored the toxicity of ApoE4 restricted by PTX. We thus conclude that one of the neurotoxic mechanisms triggered by ApoE4 is to activate a cell type-specific apoptogenic program involving LRP and the G(i) class of GTPases and that the apoE4 gene may play a direct role in the pathogenesis of AD and other forms of dementia.

Insulin-like growth factor I (IGF-I) protects cells from apoptosis by Alzheimer's V642I mutant amyloid precursor protein through IGF-I receptor in an IGF-binding protein-sensitive manner.

It has been found that insulin-like growth factor I (IGF-I) exerts cytoprotection against Abeta amyloid-induced neuronal cell death. Deposits of Abeta amyloid are one of the pathological hallmarks of Alzheimer's disease (AD). Here, we examined whether IGF-I exerts protective activity against cell death induced by a familial AD (FAD)-linked mutant of amyloid precursor protein (APP), and we found that IGF-I protected cells from toxicity of FAD-associated V642I mutant of APP in multiple cell systems. IGFBP-3 blocked this action of IGF-I, but not of des(1-3)IGF-I, which was as active as IGF-I in the presence of IGFBP-3. The data also demonstrated that the IGF-I receptor (IGF-IR) mediates the protective activity of IGF-I. The antagonizing function of the IGF-I/IGF-IR system against V642I-APP, which is further antagonized by IGFBP-3, provides a molecular clue to the understanding of AD pathophysiology and to the establishment of potential therapy for AD.

Detailed characterization of neuroprotection by a rescue factor humanin against various Alzheimer's disease-relevant insults.

A novel factor, termed Humanin (HN), antagonizes against neurotoxicity by various types of familial Alzheimer's disease (AD) genes [V642I and K595N/M596L (NL) mutants of amyloid precursor protein (APP), M146L-presenilin (PS) 1, and N141I-PS2] and by Abeta1-43 with clear action specificity ineffective on neurotoxicity by polyglutamine repeat Q79 or superoxide dismutase 1 mutants. Here we report that HN can also inhibit neurotoxicity by other AD-relevant insults: other familial AD genes (A617G-APP, L648P-APP, A246E-PS1, L286V-PS1, C410Y-PS1, and H163R-PS1), APP stimulation by anti-APP antibody, and other Abeta peptides (Abeta1-42 and Abeta25-35). The action specificity was further indicated by the finding that HN could not suppress neurotoxicity by glutamate or prion fragment. Against the AD-relevant insults, essential roles of Cys(8) and Ser(14) were commonly indicated, and the domain from Pro(3) to Pro(19) was responsible for the rescue action of HN, in which seven residues turned out to be essential. We also compared the neuroprotective action of S14G HN (HNG) with that of activity-dependent neurotrophic factor, IGF-I, or basic FGF for the antagonism against various AD-relevant insults (V642I-APP, NL-APP, M146L-PS1, N141I-PS2, and Abeta1-43). Although all of these factors could abolish neurotoxicity by Abeta1-43, only HNG could abolish cytotoxicities by all of them. HN and HN derivative peptides may provide a new insight into the study of AD pathophysiology and allow new avenues for the development of therapeutic interventions for various forms of AD.

c-Jun N-terminal kinase (JNK)-interacting protein-1b/islet-brain-1 scaffolds Alzheimer's amyloid precursor protein with JNK.

Using a yeast two-hybrid method, we searched for amyloid precursor protein (APP)-interacting molecules by screening mouse and human brain libraries. In addition to known interacting proteins containing a phosphotyrosine-interaction-domain (PID)-Fe65, Fe65L, Fe65L2, X11, and mDab1, we identified, as a novel APP-interacting molecule, a PID-containing isoform of mouse JNK-interacting protein-1 (JIP-1b) and its human homolog IB1, the established scaffold proteins for JNK. The APP amino acids Tyr(682), Asn(684), and Tyr(687) in the G(681)YENPTY(687) region were all essential for APP/JIP-1b interaction, but neither Tyr(653) nor Thr(668) was necessary. APP-interacting ability was specific for this additional isoform containing PID and was shared by both human and mouse homologs. JIP-1b expressed by mammalian cells was efficiently precipitated by the cytoplasmic domain of APP in the extreme Gly(681)-Asn(695) domain-dependent manner. Reciprocally, both full-length wild-type and familial Alzheimer's disease mutant APPs were precipitated by PID-containing JIP constructs. Antibodies raised against the N and C termini of JIP-1b coprecipitated JIP-1b and wild-type or mutant APP in non-neuronal and neuronal cells. Moreover, human JNK1beta1 formed a complex with APP in a JIP-1b-dependent manner. Confocal microscopic examination demonstrated that APP and JIP-1b share similar subcellular localization in transfected cells. These data indicate that JIP-1b/IB1 scaffolds APP with JNK, providing a novel insight into the role of the JNK scaffold protein as an interface of APP with intracellular functional molecules.

Multiple domains interacting with Gs in the porcine calcitonin receptor.

The molecular basis for Gs activation by the calcitonin (CT) receptor was investigated. Based upon the analysis of conserved regions in G protein-coupled receptors, two nonoverlapping regions in the heptahelical porcine CT receptor (CTR) were selected as candidate Gs-interacting domains: the third intracellular loop residues 327-344 (KLKESQEAESHMYLKAVR, P3 region) and the C-tail residues 404-418 (KRQWNQYQAQRWAGR, P4 region). To assess their Gs-interacting function, we expressed these sequences in hybrid insulin-like growth factor II receptors in which the receptor native Gi-interacting domain was converted to CTR sequences. In COS cells transfected with either P3- or P4-substituted hybrid receptor, membrane adenylyl cyclase activity significantly increased. The up-regulated activity of cAMP was confirmed by measuring the transcriptional activity of the cAMP response element in cells expressing either hybrid receptor. A mutant CTR lacking the P4 region maintained positive cAMP response but with an attenuated maximal capacity to produce cAMP. In contrast, we could not assess the function of the P3 region using a conventional deletion method, as CT bound poorly to cells transfected with either of the two P3-deficient CTRs (one lacking the P3 region and the other lacking P3 but having the P3 sequence in reverse orientation). These data suggest that the third intracellular loop and the C-tail in CTR have domain-specific roles in Gs activation and that the hybrid receptor approach used here, combined with a conventional mutagenesis approach, is useful for intact cell analysis and functional dissection of G protein-coupled receptors.

Interferon-gamma impairs physiologic downregulation of cyclin-dependent kinase inhibitor, p27Kip1, during G1 phase progression in macrophages.

Cell cycle progression of mouse macrophage cells was impaired by interferon-gamma (IFN-gamma). The blockage of G1/S transition was associated with diminution of cyclin-dependent kinase-2 (CDK2)-associated kinase activities. The expression of p21Cip1 was not upregulated by IFN-gamma. Instead, the physiologic downregulation of p27Kip1 necessary for normal cell cycle progression did not take place sufficiently in the presence of IFN-gamma. During normal cell cycle progression, the levels of p27Kip1 were maximal at early G1 and then decreased gradually. In the presence of IFN-gamma, however, the levels of p27Kip1 discontinued to decrease at a late mid G1 point and were consistently as high as, or higher than, levels observed there. The steady, relatively high-level attachment of p27Kip1 to CDK2 contributed to the insufficient formation of active cyclin/CDK2, possibly deferring cells from entering S phase.

A new paradigm for neurotoxicity by FAD mutants of betaAPP: a signaling abnormality.

We have demonstrated that normal betaAPP695 behave as a signaling receptor and indicated that point mutations at V642 create autoactive betaAPP in signal transduction. Cellular expression of those familial Alzheimer's disease-associated mutants causes neuronal cells to undergo apoptotic death; and procedures inhibiting the signal of normal betaAPP block the mutant-induced apoptosis. We have also shown that the mutant-induced death is mediated by intracellular G protein activity but not by secretion of Abeta peptides. Accordingly, the mutant-induced death requires a cytoplasmic domain but not the 41st and 42nd residues of the Abeta region. These studies provide a novel insight that betaAPP may play a normal role as a death receptor and that Alzheimer's disease-relevant abnormality occurred in this function may lead neurons to suicidal degeneration.

Possible requirement of serum progression factors for transformation of BALB/c 3T3 fibroblasts by v-ras p21.

To form colonies in soft agar, ras-transformed 3T3 fibroblasts require serum. We examined what growth factors in serum were essential for ras-induced transformation. Temperature-sensitive (ts) v-Ki-ras-transfected BALB/c 3T3 cells were used to strictly control both the activity of the ras protein and the cell cycle. When G0-arrested ts cells were cultured with 10% serum at a permissive temperature, greater than 50% of cells formed colonies. A similar colony-forming activity was observed in the presence of 10% platelet-poor plasma, but not in the presence of 10% plasma isolated from hypophysectomized rats. Inhibitors of IGF signals attenuated colony formation in the presence of serum. These data suggest that progression factors, probably IGFs, are essential components in serum for ras-induced transformation of 3T3 fibroblasts.

Amino acids 356-372 constitute a Gi-activator sequence of the alpha 2-adrenergic receptor and have a Phe substitute in the G protein-activator sequence motif.

The human alpha 2-adrenergic receptor contains the sequence KASRWRGRQNREKRFTF (amino acids 356-372) at the C-terminal end of its third intracellular loop. This sequence satisfies the structural criteria for G protein-activating sequences [(1992) J. Biol. Chem. 267, 8342-8346] except that the C-terminal sequence is B-B-X-X-Phe instead of B-B-X-B or B-B-X-X-B (B: basic residue, X: non-basic residue). Nevertheless, the synthetic peptide corresponding to this sequence (peptide alpha 2-F) was found to activate Gi and Go strongly with a saturated effect at 1-3 microM. Furthermore, the substitution of the C-terminal Phe of peptide alpha 2-F with Arg, Trp, and Tyr (but not Ala or Asp) did not appreciably affect the Gi-activating potency. It is suggested that the C-terminal basic residue of the B-B-X-X-B motif in Gi-activating sequences can be replaced by an aromatic residue.

Measurement of GTP gamma S binding to specific G proteins in membranes using G-protein antibodies.

We developed a novel method to quantitatively measure GTP gamma S binding to specific G proteins in crude membranes using G-protein antibodies. The basic strategy was that the materials were initially incubated with [35S]GTP gamma S at 37 degrees C. After 4 degrees C incubation in the wells of an ELISA plate precoated with G-protein antibodies, the radioactivity of each well was counted. This method, using an anti-Gi antiserum and an anti-Gs antiserum, quantitatively and specifically detected the binding of GTP gamma S to purified Gi2 and Gs. In S49 cell membranes, GTP gamma S binding to immunoreactive Gs was observed in a time-dependent manner that obeyed first-order kinetics, and the rate constant was stimulated approximately twofold in response to isoproterenol. The effect of isoproterenol was not observed in unc mutant membranes. The present method thus makes it possible to quantitatively measure GTP gamma S binding to specific G proteins in cell membranes.

Potential CRE suppression by familial Alzheimer's mutants of APP independent of adenylyl cyclase regulation.

In familial Alzheimer's disease (FAD), mutations to I, F, and G have been discovered at V642 in the neuron-specific version of the amyloid precursor protein APP695. It has been found that expression of each FAD mutant suppresses the transcriptional activity of the cAMP response element CRE in a G alpha(o)-dependent manner in a COS cell clone NK1 [Ikezu et al. (1996) EMBO J. 15, 2468-2475]. Here we show that adenylyl cyclase (AC) inhibition is probably not the prerequisite for this pathway. First, expression of each FAD mutant in NK1 cells had no effect on AC activity stimulated by cholera toxin and by mutationally activated G alpha(s), although the same expression completely repressed the stimulated CRE. Second, a transfected activating mutant of G alpha(o) inhibited CRE without detectable suppression of AC, whereas similarly transfected activating G alpha(i2) inhibited both AC and CRE. Third, FAD mutant-induced inhibition occurred for CRE activity stimulated by dibutyryl cAMP. These data suggest that CRE suppression by FAD mutants of APP could occur independently of AC.

GTP-binding protein-activator sequences in the insulin receptor.

Some functions of the insulin receptor (insR) are assumed to be mediated by pertussis toxin-sensitive Gi/G(o) proteins. Here we have located G-protein-activator domains in the cytoplasmic region of the human insR. We searched the sequence of insR and found three candidate regions at residues 1039-1061, 1147-1168 and 1325-1345, referred to as ISRP1, ISRP2 and ISRP3, respectively. Among them, the Gi/G(o)-activating function was observed only in peptide ISRP3. ISRP1 specifically activated Gs, whereas ISRP2 had no effect on G proteins. ISRP2 and ISRP3 contained five of six autophosphorylated tyrosine residues in insR. After tyrosine phosphorylation, ISRP2 showed specific Gi-activating function, and ISRP3 potentiated its ability and became capable of activating G proteins generally. This is the first study that specifies G-protein-activator domains in insR and describes their modification by autophosphorylation.

A novel system that reports the G-proteins linked to a given receptor: a study of type 3 somatostatin receptor.

SSTR3, a somatostatin (SST) receptor, is an adenylyl cyclase (AC)-inhibiting receptor. To assign the G-protein alpha-subunit (G alpha) linked to this receptor, we created a novel reporter system which utilizes the well-established facts that the C-terminal 5 residues of G alpha are the receptor contact site and G alpha(s) stimulates all subtypes of AC. We constructed chimeric G alpha(s) the C-terminal 5 residues of which were replaced with the corresponding C-terminus of each known G alpha, and examined which chimera confers SSTR3-induced activation of AC. Cellular transfection of SSTR3 and measurement of SST-dependent AC activity through co-transfected chimeric G alpha(s) revealed that SSTR3 recognizes the C-termini of G alpha(i1/2) but not of G alpha(o) or G alpha(z), and those of G alpha(14) and G alpha(16), but not of G alpha(q) or G alpha(11). As predicted by the chimeric G alpha(s), SST-bound SSTR3 stimulated polyphosphoinositide turnover only when G alpha(16) or G alpha(14) was co-transfected. We conclude that the chimeric G alpha(s) system provides a new approach towards the assignment of G-proteins linked to a given receptor.

Cytochrome P450 2E1 polymorphism in gastric cancer in Brazil: case-control studies of Japanese Brazilians and non-Japanese Brazilians.

Cytochrome P450 2E1 (Cyp2E1) is involved in the metabolic oxidation of carcinogenic nitroso compounds, including N-nitrosoamines. There is an RsaI polymorphism in the transcriptional regulatory region of this gene, and in vitro evidence suggests that the variant type of this polymorphic site has higher transcriptional activity but less chlorzoxazone-metabolizing activity. Interindividual differences in the metabolic capacity of Cyp2E1 are assumed to be associated with cancer susceptibility, but the results of the previous studies on the relation between Cyp2E1 RsaI polymorphism and cancer susceptibility have been inconsistent. Two case-control studies of gastric cancer in Japanese Brazilians (96 cases, 192 controls) and Brazilians not of Japanese ancestry (non-Japanese Brazilians; 236 cases, 236 controls) in São Paulo were designed to clarify the role of the Cyp2E1 RsaI genotype in susceptibility to gastric cancer after considering multifactorial environmental influences. The subjects with variant RsaI genotypes amounted to 47% (28 of 59) and 48% (64 of 133), respectively, of the Japanese cases and controls, and 6% (11 of 187) and 10% (19 of 192), respectively, of the non-Japanese cases and controls. As expected, a difference in the distributions of the two groups was observed. The odds ratio of the RsaI variant genotype of Cyp2E1 was 0.46 (95% confidence interval, 0.21-1.04) in the non-Japanese Brazilian population and 0.98 (95% confidence interval, 0.50-1.90) in the Japanese Brazilian population after adjusting for sex, age, tobacco use, and meat consumption. Additional adjustment for potential confounding factors did not change the odds ratio substantially. No significant interactions were observed between the polymorphism and environmental factors. In regard to the histological type of gastric cancer, the variant genotype was significantly more prevalent than the common genotype in Japanese subjects with diffuse type gastric cancer. Our study suggests that the Cyp2E1 RsaI polymorphism is associated with a reduced risk of gastric cancer, although how the assumed increase in Cyp2E1 expression produced by this polymorphism is related to a reduced risk of cancer remains unclear. The observations in this study are consistent with the recent observations of esophageal cancer in endemic areas of China.

Expression of gelatinases A and B, stromelysin-3 and matrilysin genes in breast carcinomas: clinico-pathological correlations.

The purpose of this study was to investigate the association among matrix metalloproteinases (gelatinases A and B, stromelysin-3 (ST3) and matrilysin) mRNAs expressed in primary breast carcinomas and standard prognostic parameters and clinical outcome. mRNA levels were determined by Northern analysis in samples of 81 breast cancer patients (median follow-up, 40 months) and 27 samples of uninvolved adjacent breast tissue. Proteases were expressed by the majority of the tumors and normal breast tissues examined. ST3, gelatinase A and matrilysin mRNAs were more often expressed at high levels in carcinomatous than in normal breast tissues. Differences in the distribution of gelatinase B mRNA were not found. However, paired normal tissues generally produced weaker signals when compared to matched tumor samples. Univariate analysis showed no significant association of gelatinase A and matrilysin mRNAs with the classical prognostic markers (age, menopausal status, stage, size, nodal status, vascular infiltrate, necrosis, steroid receptors, metastasis and survival). Overexpression of ST3 was more frequently found in tumors of post-menopausal women (P < 0.022). Elevated expression of gel B mRNA was associated with the presence of vascular infiltrate (P < 0.026), necrosis (P < 0.039), PR negative tumors (P < 0.014) and inversely correlated to the number of survivors (P < 0.021). Multivariate analysis including 68 patients for whom all information was available indicated that neither stromelysin correlated significantly with pathological, clinical or biochemical features. High levels of gelatinase A and B mRNAs were inversely associated with the number of survivors. Our findings suggest that measurements of gelatinase A and B mRNAs expression in breast carcinoma may help to identify patients with an aggressive form of the disease.

hOGG1 exon7 polymorphism and gastric cancer in case-control studies of Japanese Brazilians and non-Japanese Brazilians.

Polymorphism of hOGG1 may be capable of serving as a genetic marker for individual susceptibility to various cancers because of its role in the repair of oxyradical DNA damage. We examined the distribution of the hOGG1 Ser326Cys polymorphism and its presumed correlation with gastric cancer risk in two case-control studies of different ethnic groups in São Paulo, Brazil. Potentially eligible Japanese (JB) and non-Japanese Brazilian (NJB) case subjects were defined as patients with newly diagnosed malignant neoplasms of the stomach in 13 hospitals in São Paulo. Ninety-six JBs and 236 NJBs were adopted as subjects. Two controls were matched for each JB case, and one control for each NJB case. The subjects were interviewed using a questionnaire and their blood samples were collected. A significant difference in the distribution of this polymorphism between the two ethnic groups was observed (chi(2)=58.3, P<0.01). The mutant type (Ser/Cys or Cys/Cys) was predominant (approximately 65%) in the JBs, but was only present in approximately 40% of the NJBs. Logistic regression analysis showed no significant increased risk for either the Ser/Cys or Cys/Cys type in either group. The odds ratios of the Cys allele for gastric cancer were 1.01 (95% confidence interval (CI): 0.52-1.93) in the JBs and 0.85 (95% CI: 0.57-1.26) in the NJBs. In the NJBs, a significant increased risk of smoking was shown only in the Ser/Ser type, and no increased risk was shown in the genotypes with the Cys allele. However, no statistically significant interactions were observed with smoking or other possible confounding factors. No statistically significant difference in the distribution of the polymorphism was observed between the intestinal type and diffuse type of gastric cancer in either the JBs or the NJBs. The ethnic difference in hOGG1 Ser326Cys polymorphism was much greater than the case-control difference, and this polymorphism is unlikely to be associated with gastric cancer.