Serum Creatinine-Cystatin C Based Screening of Sarcopenia in Community Dwelling Older Adults: A Cross-Sectional Analysis.

OBJECTIVES: To compare the discriminative capabilities for the manifestation of sarcopenia or physical frailty between serum creatinine- and cystatin C-derived indices among community-dwelling older adults. DESIGN: Cross-sectional study. SETTING: Primary Care and Community. PARTICIPANTS: We utilized a subset of data from the Frail Elderly in the Sasayama-Tamba Area (FESTA) study, which was initiated in 2015 to gather comprehensive information on various health-related parameters among community-dwelling older individuals (age ≥65 years). MEASUREMENTS: Five serum creatinine-cystatin C based indices including the Sarcopenia Index, the serum creatinine/cystatin C ratio, the disparity between serum cystatin-C-based and creatinine-based estimated GFR, the total body muscle mass index (TBMM), and the prediction equation for skeletal muscle mass index (pSMI) were employed. Sarcopenia and physical frailty were identified based on the Asian Working Group for Sarcopenia criteria and the revised Japanese version of the Cardiovascular Health Study criteria, respectively. The receiver operating characteristic (ROC) and logistic regression analyses were performed to assess the discriminative abilities of these tools. RESULTS: In the analysis of 954 participants, 52 (5.5%) were identified with sarcopenia and 35 (3.7%) with physical frailty. Regarding sarcopenia discrimination, TBMM and pSMI both exhibited area under the curve (AUC) values exceeding 0.8 for both men and women. Concerning the identification of physical frailty, AUC values ranged from 0.61 to 0.77 for males and 0.50 to 0.69 for females. In the multivariate logistic regression analyses, only TBMM and pSMI consistently displayed associations with sarcopenia, irrespective of sex (P<0.001, respectively). On the other hand, no consistent associations were observed between the indices and physical frailty. CONCLUSIONS: This study provides a robust association of a serum creatinine- and cystatin C-derived indices, especially TBMM and pSMI, with sarcopenia among community-dwelling older adults. Conversely, the application of these indices for the screening of physical frailty has its constraints, necessitating further investigation.

A screen for potential ferredoxin electron transfer partners uncovers new, redox dependent interactions.

Ferredoxin (Fd) is the primary soluble acceptor at the end of the photosynthetic electron transport chain, and is known to directly transfer electrons to a wide range of proteins for use in metabolism and regulatory processes. We have conducted a screen to identify new putative Fd interaction partners in the cyanobacteria Synechocystis sp. PCC 6803 using Fd-chromatography in combination with MALDI-TOF mass spectrometry. Many novel interactions were detected, including several redox enzymes, which are now candidates for further experiments to investigate electron transfer with Fd. In addition, some proteins with regulatory activity related to photosynthesis were identified. We cloned and expressed one such protein, known as RpaA, which is a specific regulator of energy transfer between phycobilisomes and PSI. Using the recombinant protein we confirmed direct interaction with Fd, and discovered that this was dependent on redox state. The screen for putative Fd-binding proteins was repeated, comparing oxidizing and reducing conditions, identifying many proteins whose interaction with Fd is redox dependent. These include several additional signaling molecules, among them the LexA repressor, Ycf53 and NII, which are all involved in interpreting the redox state of the cell.

Therapeutic results of the modified Cadenat procedure for acromioclavicular joint separations compared with the modified Dewar procedure.

AIM AND BACKGROUND: The surgical treatment for acromioclavicular joint dislocations is recommended for Rockwood's classification types 4, 5 and 6. In this study we evaluate the therapeutic results of the modified Cadenat procedure on type 5 acromioclavicular joint dislocation, and report on a comparative study of the modified Dewar procedure also on type 5 acromioclavicular joint dislocation. SUBJECTS AND METHODS: The modified Cadenat procedure was performed on 73 patients (66 males and 7 females, group C). The mean age at the time of the surgery was 35.4 years. On the other hand, the modified Dewar procedure was performed on 55 patients (51 males and 4 females, group D). The mean age at the time of the surgery was 34.5 years. RESULTS: The mean therapeutic results were 28.2 points in group C and 27.3 in group D according to the UCLA scoring system. In group C, the subluxation that represented less than 5 mm superior translation of the clavicle, occurred only in 18 of 73 patients. Meanwhile, in group D, the subluxation that represented less than 5 mm, occurred only in 14; that which represented 5 to 10 mm was in seven patients, and the complete dislocation occurred in three patients. Also, the occurrence of osteoarthritic changes in the acromioclavicular joint was nine patients in group C and 20 in group D, respectively. CONCLUSION: The modified Cadenat procedure could provide satisfactory therapeutic results and avoid postoperative failure of reduction compared to the modified Dewar procedure. However the modified Cadenat procedure does not aim to restore the anatomical coracoclavicular ligaments. It is believed that anatomic restoration of both coracoclavicular ligaments could best restore the function of the acromioclavicular joint.

Relevance of level IIb neck dissection in patients with papillary thyroid carcinoma.

BACKGROUND: Cervical nodal metastasis is a key prognostic factor in patients with papillary thyroid carcinoma. The role of lymph nodes in papillary thyroid carcinoma management and prognosis remains controversial. METHODS: Level IIb lymph nodes obtained from 44 patients with papillary thyroid carcinoma were histopathologically examined retrospectively. Specimens were classified as ipsilateral or contralateral. The number of dissected nodes and prevalence of level IIb metastasis were compared according to pre-operative clinical nodal stage. RESULTS: In the node-negative neck, the prevalence of contralateral and ipsilateral IIb nodes was 0 out of 20 and 0 out of 3, respectively. In the node-positive neck, the prevalence of contralateral and ipsilateral IIb nodes was 1 out of 13 (7.70 per cent) and 3 out of 41 (7.32 per cent), respectively. Clinically determined and pathologically confirmed level IIb node negativity were significantly associated. Thirty-four patients (77.3 per cent) developed accessory nerve complications from level IIb dissection. CONCLUSION: Level IIb neck dissection for papillary thyroid carcinoma may be required if pre-operative examination reveals multilevel, level IIa or suspicious level IIb metastasis.

Human Sgo1 downregulation leads to chromosomal instability in colorectal cancer.

BACKGROUND AND AIMS: Chromosomal instability (CIN) is recognised as a hallmark of cancer and is caused by a spindle assembly checkpoint disorder or chromosome mis-segregation during mitosis. Although the recent identification of human shugoshin (hSgo1), an important player in proper chromosome segregation, has suggested the involvement of hSgo1 in colorectal tumourigenesis, little is known about how it is involved. The aim of this study was to obtain information about the status of hSgo1 in human colorectal cancer. METHOD AND RESULTS: Among the 46 colorectal cancer cases, hSgo1 mRNA expression was decreased in the tumour tissue in comparison with the corresponding normal tissue (p = 0.032). Human Sgo1-downregulated tumours (tumour to normal mucosa ratio<0.5) had preferential location on the left side large bowel rather than on the right side (p = 0.012), and a higher variation of centromere numbers revealed by fluorescence in situ hybridisation (FISH). To assess the effects of hSgo1 downregulation, hSgo1 knockdown was performed by transfecting the diploid HCT116 cell line with a short hairpin RNA expression vector. hSgo1 knockdown cells proliferated slowly because of both G(2)/M arrest and apoptosis (p<0.001), and markers of CIN in the form of aneuploidy (p<0.001) and micronuclei (p<0.005) were later observed in hSgo1 knockdown cells. Increased centrosome amplification (p<0.05), the presence of binucleated cells and mitotic catastrophes were also noted in hSgo1 knockdown cells. CONCLUSIONS: These findings suggest that hSgo1-downregulated colorectal cancers have a clinicopathological character of CIN, and hSgo1 downregulation leads to CIN in colorectal cancer cells.

Induction of centrosome amplification and chromosome instability in p53-deficient lung cancer cells exposed to benzo[a]pyrene diol epoxide (B[a]PDE).

Benzo[a]pyrene diol epoxide (B[a]PDE), the ultimate carcinogenic metabolite of benzo[a] pyrene, has been implicated in the mutagenesis of the p53 gene involved in smoking-associated lung cancer. To further understand the role of B[a]PDE in lung tumour progression, we investigated its effect on the numerical integrity of centrosomes and chromosome stability in lung cancer cells lacking p53. Exposure of p53-deficient H1299 lung cancer cells to B[a]PDE resulted in S-phase arrest, leading to abnormal centrosome amplification. Analysis of H1299 cells stably expressing fluorescence-tagged centrin (a known centriolar marker) revealed that the centrosome amplification was primarily attributable to excessive centrosome duplication rather than to centriole splitting. Forced expression of POLK DNA polymerase, which has the ability to bypass B[a]PDE-guanine lesions in an error-free manner, suppressed the B[a]PDE-induced centrosome amplification. Fluorescence in situ hybridization analyses with probes specific for chromosomes 2, 3, and 16 revealed that B[a]PDE exposure also led to chromosome instability, which was likely to have resulted from centrosome amplification. We extended these findings to primary lung carcinomas containing non-functional p53, and found a strong association between centrosome amplification and a high level of B[a]PDE-DNA accumulation. Therefore B[a]PDE contributes to neoplasia by inducing centrosome amplification and consequent chromosome destabilization as well as its mutagenic activity.

Direct evidence for the role of centrosomally localized p53 in the regulation of centrosome duplication.

Abnormal amplification of centrosomes is the major cause of mitotic defects and chromosome instability in cancer cells. Centrosomes duplicate once in each cell cycle, and abrogation of the regulatory mechanism underlying centrosome duplication leads to centrosome amplification. p53 tumor suppressor protein is involved in the regulation of centrosome duplication: loss of p53 as well as expression of certain p53 mutants result in deregulated centrosome duplication and centrosome amplification. p53 at least in part depends on its transactivation function to control centrosome duplication, primarily via upregulation of p21 cyclin-dependent kinase (CDK) inhibitor, which prevents untimely activation of CDK2/cyclin E, a key initiator of centrosome duplication. However, numerous studies have shown the presence of p53 at centrosomes, yet the role of the centrosomally localized p53 in the regulation of centrosome duplication had been enigmatic. Here, we comparatively examined wild-type p53 and p53 mutants that are transactivation(+)/centrosome-binding(-), transactivation(-)/centrosome-binding(+) and transactivation(-)/centrosome-binding(-) for their abilities to control centrosome duplication. We found that the transactivation(+)/centrosome-binding(-) and transactivation(-)/centrosome-binding(+) mutants suppress centrosome duplication only partially compared with wild-type p53. Moreover, the transactivation(-)/centrosome-binding(-) mutant almost completely lost the ability to suppress centrosome duplication. These observations provide direct evidence for the centrosomally localized p53 to participate in the regulation of centrosome duplication in a manner independent of its transactivation function in addition to its transactivation-dependent regulation of centrosome duplication.

Adenine excisional repair function of MYH protein on the adenine:8-hydroxyguanine base pair in double-stranded DNA.

Adenine paired with 8-hydroxyguanine (oh(8)G), a major component of oxidative DNA damage, is excised by MYH base excision repair protein in human cells. Since repair activity of MYH protein on an A:G mismatch has also been reported, we compared the repair activity of His(6)-tagged MYH proteins, expressed in Spodoptera frugiperda Sf21 cells, on A:oh(8)G and A:G mismatches by DNA cleavage assay and gel mobility shift assay. We also compared the repair ability of type 1 mitochondrial protein with type 2 nuclear protein, as well as of polymorphic type 1-Q(324) and 2-Q(310) proteins with type 1-H(324) and 2-H(310) proteins by DNA cleavage assay and complementation assay of an Escherichia coli mutM mutY strain. In a reaction buffer with a low salt (0-50 mM) concentration, adenine DNA glycosylase activity of type 2 protein was detected on both A:oh(8)G and A:G substrates. However, in a reaction buffer with a 150 mM salt concentration, similar to physiological conditions, the glycosylase activity on A:G, but not on A:oh(8)G, was extremely reduced and the binding activity of type 2 protein for A:G, but not for A:oh(8)G, was proportionally reduced. The glycosylase activity on A:oh(8)G and the ability to suppress spontaneous mutagenesis were greater for type 2 than type 1 enzyme. There was apparently no difference in the repair activities between the two types of polymorphic MYH proteins. These results indicate that human MYH protein specifically catalyzes the glycosylase reaction on A:oh(8)G under physiological salt concentrations.

Greater development of 1,2-dimethylhydrazine-induced colon cancer in a rat model of type 2 diabetes mellitus.

Several clinical cohort and case-control studies have suggested a link between diabetes and colon cancer. Otsuka Long-Evans Tokushima Fat (OLETF) rats spontaneously develop type 2 diabetes mellitus and Long-Evans Tokushima Otsuka (LETO) rats are non-diabetic. The relationship between type 2 diabetes mellitus and colon cancer was examined in these rats. The carcinogen 1,2-dimethylhydrazine was administered subcutaneously once weekly for 10 weeks, and the animals were killed and necropsied in week 29. All OLETF rats and 80% of the LETO rats developed cancer. The number of colon cancers per rat was significantly greater in the diabetic than in the non-diabetic rats. Although the tumours tended to be larger in diabetic rats, the difference was not statistically significant. No significant differences were observed in the depth of invasion or histological type of cancer in the two groups. Type 2 diabetes mellitus may enhance the generation and growth of colon cancer.

Cloning of a human homolog of the yeast OGG1 gene that is involved in the repair of oxidative DNA damage.

We report the cloning of a human homolog of the yeast OGGC1 gene, which encodes a DNA glycosylase that excises an oxidatively damaged form of guanine, 8-hydroxyguanine (also known as 7,8-dihydro-8-oxoguanine). Since the deduced amino acid sequence (68 amino acids) of a human expressed sequence tag, N55394, matched a short stretch of yeast OGG1 protein with greater than 40% amino acid identity, a full length cDNA clone was isolated from a HeLa cell cDNA library with the N55394 clone as a probe. The cDNA clone encodes a predicted protein of 345 amino acids which is homologous to yeast OGG1 protein throughout the entire polypeptide sequence and shares 38% amino acid identity with yeast OGG1 protein. Moreover, we found that both a human homolog and yeast OGG1 protein possess two distinct DNA binding motifs, a helix-hairpin-helix (HhH) motif and a C2H2 zinc finger like motif, and a domain homologous to human and E. coli MutY proteins. Expression of a human homolog suppressed spontaneous mutagenesis of an E. coli (mutM mutY) mutant as in the case of yeast OGG1 protein. The gene was ubiquitously expressed in a variety of human organs and mapped to chromosome 3p26.2. These results strongly suggest that the gene isolated here is a human counterpart of the yeast OGGI gene and is involved in the repair of oxidative DNA damage in human cells.

Genetic polymorphisms and alternative splicing of the hOGG1 gene, that is involved in the repair of 8-hydroxyguanine in damaged DNA.

The hOGG1 gene encodes a DNA glycosylase that excises 8-hydroxyguanine (oh8Gua) from damaged DNA. Structural analyses of the hOGG1 gene and its transcripts were performed in normal and lung cancer cells. Due to a genetic polymorphism at codon 326, hOGG1-Ser326 and hOGG1-Cys326 proteins were produced in human cells. Activity in the repair of oh8Gua was greater in hOGG1-Ser326 protein than in hOGG1-Cys326 protein in the complementation assay of an E. coli mutant defective in the repair of oh8Gua. Two isoforms of hOGG1 transcripts produced by alternative splicing encoded distinct hOGG1 proteins: one with and the other without a putative nuclear localization signal. Loss of heterozygosity at the hOGG1 locus was frequently (15/ 23, 62.2%) detected in lung cancer cells, and a cell line NCI-H526 had a mutation leading to the formation of the transcripts encoding a truncated hOGG1 protein. However, the oh8Gua levels in nuclear DNA were similar among lung cancer cells and leukocytes irrespective of the type of hOGG1 proteins expressed. These results suggest that the oh8Gua levels are maintained at a steady level, even though multiple hOGG1 proteins are produced due to genetic polymorphisms, mutations and alternative splicing of the hOGG1 gene.

Inhibition of glycolysis or increased perfusate H+ buffering capacity, but not their combination, attenuates myocardial stunning.

OBJECTIVE: Both inhibition of glycolysis and enhancement of the H+ buffering capacity of the perfusate during ischaemia reduce myocardial reperfusion injury. The aim of the study was to investigate whether these manoeuvres, performed separately or together, could reduce myocardial stunning after brief global ischaemia. METHODS: The hearts of male Sprague-Dawley rats were preperfused for 10 min with oxygenated or hypoxic buffer (pH 7.4) containing 100 mM sucrose, 100 mM HEPES, or 5 mM 2-deoxyglucose plus 100 mM sucrose, followed by 15 min of total ischaemia and 30 min of reperfusion. In some hearts, 5 mM 2-deoxyglucose was combined with 100 mM HEPES during the 10 min preperfusion period. RESULTS: Brief hypoxic preperfusion, 2-deoxyglucose, or HEPES reduced myocardial stunning as well as improving the metabolic recovery and reducing Ca2+ overload after reperfusion. These changes were associated with a smaller increase in intracellular Na+ and a smaller decrease of coronary effluent pH at the end of ischaemia. In contrast, the combination of HEPES with hypoxic preperfusion or 2-deoxyglucose depressed functional recovery and increased the intracellular Na+ level at the end of ischaemia as well as increasing Ca2+ overload after reperfusion. This happened even though the decrease in coronary effluent pH was attenuated to the same extent as before. CONCLUSIONS: Both inhibition of glycolysis and enhancement of the perfusate H+ buffering capacity before ischaemia attenuated myocardial stunning, but the protective effect of each manoeuvre was lost when they were combined.

Loss of protection by hypoxic preconditioning in aging Fischer 344 rat hearts related to myocardial glycogen content and Na+ imbalance.

OBJECTIVES: The objective of this study was to determine whether hypoxic preconditioning (HP) could lessen the myocardial increase in [Na+]i, thus protecting the aging myocardium against ischemia. BACKGROUND: A decrease in ischemic tolerance with aging is associated with an accelerated increase in [Na+]i during ischemia. Ischemic preconditioning fails to protect the middle-aged and senescent myocardium against ischemia. METHODS: Isolated hearts of young adult (12-week-old), middle-aged (50-week-old) and senescent (100-week-old) Fischer 344 rats were subjected to 25 min of ischemia with or without HP followed by 30 min of reperfusion. Left ventricular (LV) function, myocardial energy metabolites and [Na+]i were measured. RESULTS: In the older groups, the recovery of LV function and high-energy phosphates (HEPs) was lower with an increased release of creatine kinase (CK) during reperfusion than in the young group. The increased [Na+]i at the end of ischemia was greater in the former groups than in the young group. HP decreased myocardial glycogen and lessened the increased [Na+]i in the young group, resulting in an improved recovery of LV function and HEPs, as well as decreased CK release. However, the levels of glycogen before HP in the older groups were higher than in the young group and its levels after HP were similar to that before HP in the young group. HP did not affect the [Na+]i, exacerbated CK release and inhibited the recovery of LV function and HEPs in the older groups. CONCLUSIONS: HP failed to lessen the increased [Na+]i or to protect the aging hearts, probably due to the preexistence of increased glycogen level.

Effect of brief hypoxia on reperfusion arrhythmias and release of Ca2+ by rat heart homogenate blocked by ryanodine.

OBJECTIVES: We previously reported that a brief period of hypoxic perfusion (BHP) prior to ischemia in rat hearts improved functional recovery upon reperfusion with reduced Ca2+ overload. The present study was designed to determine whether the effect of BHP would be associated with a reduction in reperfusion arrhythmias and a preservation of function of the sarcoplasmic reticulum (SR). METHODS: Hearts were subjected to 40 min of global ischemia and 30 min of reperfusion after a 20 min period of oxygenated perfusion (oxygenated group: OG), or a 10 min period of oxygenation and 10 min of hypoxic perfusion (hypoxic group: HG). We evaluated the release of Ca2+ by SR blocked by ryanodine, the recovery of left ventricular function, and the reperfusion induced ventricular tachycardia/fibrillation (VT/VF). RESULTS: Functional recovery improved and the incidence and duration of reperfusion VT/VF were reduced in HG. In HG the uptake of Ca2+ in SR decreased during ischemia, but this decrease was less than that in OG. However, recovery of Ca2+ uptake after reperfusion did not differ between groups. The release of Ca2+ by SR blocked by ryanodine was inhibited in HG throughout the ischemia-reperfusion sequence. CONCLUSIONS: Observations suggest that the benefits of BHP on recovery of function and reperfusion arrhythmias were associated with a decrease in release of Ca2+ by SR blocked by ryanodine.

The OGG1 gene encodes a repair enzyme for oxidatively damaged DNA and is involved in human carcinogenesis.

8-Hydroxyguanine (oh8G) is a major base lesion produced by reactive oxygen species. oh8G in DNA causes G:C to T:A transversions and, thus, could be responsible for mutations that lead to carcinogenesis. A human DNA glycosylase/AP lyase encoded by the OGG1 gene has an activity to remove directly oh8G from DNA, and suppresses the mutagenic effect of oh8G. OGG1 protein has a helix-hairpin-helix-GPD motif as a domain for both DNA binding and catalysis, a nuclear localization signal, and a mitochondria targeting signal. Among multiple OGG1 isoforms, OGG1-type la is expressed predominantly in human cells and repairs chromosomal DNA in the nucleus. Inactivation of the OGG1 gene in yeast and mice leads to elevated spontaneous mutation frequency in the cells. The human OGG1 gene maps to chromosome 3p26.2, and allelic deletions of this region occur frequently in a variety of human cancers. Moreover, the OGG1 gene is somatically mutated in some cancer cells and is highly polymorphic among human populations. Repair activities of some mutated and polymorphic OGG1 proteins are lower than those of wild-type OGG1-type la-Ser326 protein and, thus, could be involved in human carcinogenesis.

Expression of IFN-gamma in cerebrovascular endothelial cells from aged mice.

Recently, it has become clear that interferon-gamma (IFN-gamma) plays a role in the central nervous system (CNS) as well as in the immune system. However, the reason for the alteration in IFN-gamma production in the brain with aging remains unknown. In this study, we investigated the expression of IFN-gamma in the brain in terms of both mRNA and protein and compared the expression in young adult brain with that in aged mice. The cerebrum and cerebellum were collected from young adult (8-10 weeks old) and aged (24-26 months old) BALB/c mice, and the expressions of IFN-gamma and IFN-gamma receptor-1 (IFNGR-1) mRNA were examined by RT-PCR. Expression of IFN-gamma mRNA was detected in the brains from aged mice but not in those from young adult mice. However, IFNGR-1 mRNA was expressed in the brains from both young adult and aged mice. Moreover, IFN-gamma levels in the cerebrum and cerebellum from aged mice were detectable by ELISA, but IFN-gamma was undetectable in these tissues from young adult mice. To identify the cellular source of IFN-gamma in the brain of aged mice, immunostaining using antimouse IFN-gamma monoclonal antibody (mAb) was done. Immunoreactivity of IFN-gamma appeared to be located in cerebrovascular endothelial cells, including the choroid plexus of the cerebellum from aged mice. Expression of IFN-gamma and IFNGR-1 was also identified in isolated microvessels from brains. These results suggest that IFN-gamma plays a role in age-associated changes.

Stage-dependent evaluation of microsatellite instability in gastric carcinoma with familial clustering.

Familial clustering of gastric cancer is probably caused by multifactorial processes, both environmental and genetic. In this report, the incidence of microsatellite instability (MSI) in 31 cases of gastric cancer in Japanese (33 lesions) with familial clustering (two or more gastric cancers within second-degree relatives) was compared to MSI in Japanese cases without a family of any cancer in age ( +/- 10 years)-, stage-, and histological subtype-matched case-control study. Although the difference noted was not significant, we noted a strong trend for MSI at any of up to seven loci of CA repeats to occur more frequently in the patients with a family history of gastric than in the control patients in early cancer (intramucosal and submucosal), whereas the prevalence of MSI was similar in both groups in more advanced cases, in which the tumor invaded beyond the proper muscle layer of the gastric wall. Because the contribution of a family history of gastric cancer to MSI apparently differs in early and advanced gastric cancer, interpretation of MSI in familial gastric cancer cases published previously require reevaluation in terms of stage and proper controls. An acquisition of CA repeat alterations in the early stage rather than in the late stage of gastric carcinogenesis may have in common etiological factors, at least in some cases, with the familial clustering of gastric cancer.

hOGG1 Ser326Cys polymorphism and lung cancer susceptibility.

The human homologue of the yeast OGG1 gene, hOGG1, has been cloned, and its genetic structure has been determined. Several polymorphisms in the hOGG1 gene were detected in the Japanese populations, and among them, the Ser-Cys polymorphism at codon 326 has been shown to have a functional difference in complementation of mutant Escherichia coli that is defective in the repair of 8-hydroxyguanine. Activity in the repair of 8-hydroxyguanine is greater in hOGG1-Ser326 protein than in hOGG1(326) protein. Because many environmental carcinogens produce 8-hydroxyguanine residue and mismatching to this modified base potentially causes oncogenic mutations, the capacity to repair these lesions can be involved in cancer susceptibility in human beings. We, therefore, examined allele distributions of the Ser326Cys polymorphism in a case-control study of male lung cancer in Okinawa. The analyses based on 241 cases and 197 hospital controls disclosed the following findings. (a) Those with the Cys/Cys genotype were at an increased risk of squamous cell carcinoma and nonadenocarcinoma compared to those with the Ser/Cys and those with the Ser/Ser genotypes combined. The odds ratios adjusted for age and smoking history were 3.01 (95% confidence interval, 1.33-6.83) and 2.18 (95% confidence interval, 1.05-4.54), respectively. (b) The odds ratios for other histological subtypes of lung cancer or those in total were not significant. Those for Cys/Cys or Ser/Cys genotype against Ser/Ser did not reach statistical significance in any cell type. (c) The distributions of this polymorphism varied for different populations (Chinese, Japanese, Micronesians, Melanesians, Hungarians, and Australian Caucasians), with much less prevalence of Cys allele in the latter three populations. Although our sample size was limited, these results indicate that the Ser326Cys variant may be related to squamous cell lung cancer susceptibility. The Cys/Cys genotype appears to be more susceptible to squamous cell carcinoma, although the risk is less than that previously reported to be associated with the CYP1A1 gene. Further studies are needed to assess the importance of the interpopulation variation to cancer susceptibility.

Somatic mutations and single nucleotide polymorphisms of base excision repair genes involved in the repair of 8-hydroxyguanine in damaged DNA.

To elucidate the involvement of 8-hydroxyguanine (oh(8)G) repair genes in human lung carcinogenesis, 47 lung cancer cell lines and 55 primary lung cancers were examined for somatic mutations and genetic polymorphisms in all coding exons of the MYH and APEX genes, and exon 8 of the OGG1 gene by polymerase chain reaction-single strand conformation polymorphism analysis. In the MYH gene, one missense mutation was detected in a cell line, NCI-H157, whereas no mutations were detected in primary cancers. There were no mutations in the APEX and OGG1 genes in the cell lines or primary cancers. Ten single nucleotide polymorphisms (SNPs) were identified, and seven of them were accompanied by amino acid substitutions. Differences in the oh(8)G repair activities of MYH, APEX and OGG1 proteins due to somatic mutations and SNPs can be involved in human carcinogenesis.

Expression of the OGG1-type 1a (nuclear form) protein in cancerous and non-cancerous human cells.

The human OGG1 gene encodes 8-hydroxyguanine DNA glycosylase. By RT-PCR analysis, five novel type 1 transcripts, in addition to eight known types (OGG1-types 1a to 1c and 2a to 2e), were identified. Among them, only the type 1a isoform contains both a nuclear localization signal and the entire DNA binding motif, suggesting the involvement of type 1a in chromosomal DNA repair. By Western blot analysis using a monoclonal antibody prepared by immunizing the whole type 1a protein, a 39 kDa type 1a protein was detected in lung cancer cell lines and peripheral lymphocytes. The type 1a protein was expressed at a similar level, irrespective of its polymorphic types characterized by distinct repair activity. By an immunocytochemical study, the majority of type 1a protein was localized in the nucleus. These results indicate that OGG1-type 1a protein is involved in the repair of 8-hydroxyguanine in chromosomal double-stranded DNA and constitutively expressed in cancerous and non-cancerous human cells.