Apoptosis, necroptosis and autophagy in colorectal cancer: Associations with tumor aggressiveness and p53 status

OBJECTIVE

Cleaved caspase-3 (CC3), phosphorylated-mixed-lineage kinase domain-like protein (p-MLKL), and microtubule-associated protein-1 light chain-3B (LC3B) have pivotal functions in apoptosis, necroptosis, and autophagy, respectively. In vitro studies have shown that interaction of these proteins are complex and their roles in cancer can be influenced by many factors. However, these findings are not adequately assessed in human tissues. Here, we determined CC3, p-MLKL, and LC3B expression in colorectal cancers (CRCs), and assessed their associations with clinicopathological parameters, and with KRAS and p53 status.

METHODS

We immunohistochemically assessed 113 CRC specimens for levels of CC3, p-MLKL, LC3B, and p53. KRAS gene status was analyzed using the Scorpion- amplification refractory mutation system.

RESULTS

High levels of CC3 (CC3^High) and LC3B (LC3B^High) were detected in 38% and 35% of the 113 CRCs, respectively, but no or only a few p-MLKL-positive cells were observed in any of the tumors. CC3^High was significantly associated with high pT status (P = 0.03), vascular invasion (P = 0.03) and high pStage (P = 0.04) and was marginally associated with lymph node (P = 0.06) and distant metastases (P = 0.06). LC3B^High was also significantly associated with high pT status (P = 0.02) and lymphatic invasion (P = 0.002), and was marginally associated with nerve plexus invasion (P = 0.06). In combined analysis, compared with CC3^Low/LC3B^Low tumors, tumors that were either CC3^High, LC3B^High, or both were significantly associated with high pT status (P = 0.0007), lymphatic invasion (P = 0.03), vascular invasion (P = 0.003), distant metastasis (P = 0.04) and high pStage (P = 0.04). LC3B^High was significantly associated with a mutant-type expression pattern of p53 (P = 0.003).

CONCLUSION

To the best of our knowledge, this is the first study to examine the combination of CC3/LC3B and p-MLKL expression in clinical CRC samples and to correlate these expression data with clinicopathological parameters and EGFR and p53 status. Our results suggest that necroptosis is a rare process in CRC, apoptosis and autophagy are upregulated in aggressive CRCs, and p53 mutation may lead to the upregulation of autophagy.

Autophagy in normal tissues of camel (Camelus dromedarius) with focus on immunoexpression of LC3 and LC3B

Autophagy is a highly regulated intracellular pathway for degradation and recycling of cytoplasmic protein aggregates and entire organelles. The autophagic pathway is stimulated by nutrient starvation, which prompted us to study the desert camel. Various organs of the camel undergo ecological and physiological stress due to food and water deprivation, dehydration and long exposure to solar radiation. We investigated the immunohistochemical expression of specific biomarkers of autophagy under normal conditions as a baseline for later work on stressed individuals. The autophagy-specific biomarkers, microtubule-associated protein1 light chain 3 (LC3), and its cleaved variant, LC3B, were strongly expressed in the cytosol of all tissues examined. The cytosolic immunoreactivity of LC3 was relatively weak, diffuse and vacuolar, while that of LC3B was stronger, punctate and at lower levels. LC3 appears to be associated with the autophagosomal membranes, either free or lysosome-bounded. LC3B is specific for the autophagosome-lysosome complexes and their degraded, granular contents. Autophagy was strongly expressed in CNS neurons and intestinal neural elements, which suggests a protective function for the nervous system. Autophagic markers also were seen in deformed immune-competent cells with fragmented nuclei in lymph nodes, spleen and gut-associated lymphoid tissue (GALT), which suggests a "suicidal" activity of eliminating unneeded cells. Autophagy, as measured by LC3 and LC3B expression, may participate in a general regulatory mechanism in tissues of the desert camel.

Anti-hyperglycemic Effect of Long-Term Bis(hinokitiolato)zinc Complex ([Zn(hkt)2]) Ingestion on Insulin Resistance and Pancreatic Islet Cells Protection in Type 2 Diabetic KK-Ay Mice

Zinc (Zn) is a trace element with anti-diabetes mellitus (anti-DM) effects. Zn complexes exhibit stronger insulin-like activity than Zn ions. Bis(hinokitiolato)zinc complex ([Zn(hkt)₂]) was recently reported to be a potent anti-DM candidate. We examined the effects of [Zn(hkt)₂] on insulin resistance and pancreatic islet cells through in vivo long-term ingestion studies. In an in vivo study, we performed 4-month long-term [Zn(hkt)₂] administration experiments in KK-A^y mice as a type 2 DM animal model. Ingestion of [Zn(hkt)₂] resulted in lower blood glucose levels compared with the non-treated KK-A^y mice (control group). Additionally, [Zn(hkt)₂] treatment decreased plasma insulin concentration compared with that of the non-treated KK-A^y group. [Zn(hkt)₂] treatment resulted in a significant suppression of islet cell enlargement and a significantly decreased number of insulin-positive cells compared with the non-treated KK-A^y control group. The [Zn(hkt)₂] treatment group showed the increasing tendency in the amount of Zn levels in peripheral organs; liver, muscle, adipose, and pancreas, compared with the non-treated KK-A^y control group. However, the Zn level in the pancreas of the [Zn(hkt)₂] treatment group did not show the significant increase compared with the non-treated KK-A^y control group. This accumulation of Zn in pancreas suggested that [Zn(hkt)₂] mainly effects on the peripheral tissue, and [Zn(hkt)₂] has the less effect on the pancreas directly. Thus, we concluded that [Zn(hkt)₂] exerted the main effect on peripheral organs by ameliorating insulin resistance.

Expression of chromosomal regional maintenance protein-1 may be associated with subcellular survivin expression in human gastric and colorectal carcinoma

Survivin, a member of the inhibitor of apoptosis protein family, is a potential prognostic marker and molecular target for anticancer therapies. Chromosomal regional maintenance protein-1 (CRM-1) mediates the nuclear export of proteins such as survivin. The aims of the present study were to compare the expression and subcellular localization of CRM-1 in human gastric and colorectal carcinomas and to assess the association between CRM-1 and survivin expression in these tumor types. The nuclear and cytoplasmic CRM-1 expression rates in gastric carcinoma were 61% (42/69) and 29% (20/69), respectively, while the nuclear and cytoplasmic CRM-1 expression rates in colorectal carcinoma were 55% (43/78) and 37% (29/78), respectively. Nuclear and cytoplasmic CRM-1 expression was found to be significantly correlated with nuclear and cytoplasmic survivin expression in colorectal carcinoma, but not gastric carcinoma. These results indicate that CRM-1 expression patterns differ between gastric and colorectal carcinomas and thus, we hypothesize that CRM-1-mediated nuclear export of survivin may be deregulated in gastric carcinoma. Therefore, CRM-1 may exhibit different functions in gastric and colorectal carcinoma.

Localization of Palatal Area in Human Somatosensory Cortex

To determine the ’hard palate representing’ area in the primary somatosensory cortex, we recorded somatosensory-evoked magnetic fields from the cortex in ten healthy volunteers, using magnetoencephalography. Following electrical stimulation of 3 sites on the hard palate (the first and third transverse palatine ridges, and the greater palatine foramen), magnetic responses showed peak latencies of 15, 65, and 125 ms. Equivalent current dipoles for early magnetic responses were found along the posterior wall of the inferior part of the central sulcus. These dipoles were localized anterior-inferiorly, compared with locations for the hand area in the cortex. However, there were no significant differences in three-dimensional locations among the 3 selected regions for hard palate stimulation. These results demonstrated the precise location of palatal representation in the primary somatosensory cortex, the actual area being small.

Organic cation transporter 2 for predicting cisplatin-based neoadjuvant chemotherapy response in gastric cancer

Some studies have shown the usability of neoadjuvant chemotherapy (NAC) in gastric cancer (GC). Nevertheless there are a few predictive markers of the effectiveness of NAC in GC. The aim of this study is to assess the predictive impact of organic cation transporter 2 (OCT2) expression on response to neoadjuvant chemotherapy (NAC) in gastric cancer. We retrospectively assessed 66 patients with advanced gastric cancer received NAC with S-1/cisplatin or paclitaxel/cisplatin. Expression levels of OCT2 were assessed by immunohistochemistry in pre-chemotherapy biopsies and correlated with clinicopathologic parameters including pathologic response. High expression level of OCT2 (OCT2(high)) was significantly associated with intestinal type according to Laurén classification (P = 0.03) and low histologic grade (P = 0.03). In univariate analysis of the entire cohort, no variables showed any significant association with a response, although intestinal type (P = 0.09), low histologic grade (P = 0.09), and OCT2(high) (P = 0.07) tended to be more frequent in responders compared with non-responders. When the two treatment groups were separately assessed in the univariate analysis, a significantly higher rate of OCT2(high) was observed in responders compared with non-responders in the S-1/cisplatin group (P = 0.001). In addition, multivariate analysis identified OCT2(high) as the sole independent predictor of response (P = 0.04). However, in the paclitaxel/cisplatin group, no variables were associated with response. Taken together, our results suggest that OCT2(high) may represent a potential predictor of response to NAC with S-1/cisplatin in gastric cancer.

Smac/DIABLO expression in human gastrointestinal carcinoma: Association with clinicopathological parameters and survivin expression

Lack of apoptosis is a key factor in carcinogenesis and tumor progression. Survivin is a member of the inhibitor of apoptosis protein (IAP) family. Second mitochondria-derived activator of caspases/direct inhibitor of apoptosis-binding protein with low pI (Smac/DIABLO) is an antagonist of IAPs. Recently, Smac/DIABLO was identified as a potent therapeutic target. However, the clinical significance of Smac/DIABLO in gastrointestinal carcinomas remains unclear. In the present study, Smac/DIABLO expression was analyzed by immunohistochemistry in 72 gastric adenocarcinomas and 78 colorectal adenocarcinomas. The expression of Smac/DIABLO was significantly higher in colorectal carcinoma than in gastric carcinoma. Additionally, a correlation was found between the expression of Smac/DIABLO and nuclear survivin in well- to moderately-differentiated colorectal adenocarcinomas (r=0.245; P<0.01). Based on these results, it was hypothesized that gastric and colorectal carcinomas differ in the level of Smac/DIABLO expression. Our previous studies revealed that the expression of cleaved caspase-9 was significantly lower in colorectal carcinoma than in gastric carcinoma (P<0.0001). Conversely, the expression levels of microtubule-associated protein 1 light chain 3 (LC3), an autophagy marker, and survivin were significantly higher in colon cancer than in gastric cancer (P<0.0001 and P<0.01, respectively). Taken together, these results indicate that not only LC3 and survivin expression, but also Smac/DIABLO expression, are significantly higher in colorectal carcinoma than in gastric carcinoma. We hypothesize that the analysis of Smac/DIABLO, survivin and LC3 expression in colorectal carcinoma is likely to aid cancer therapy due to the involvement of these markers in apoptosis and/or autophagy.

Phosphorylation status of Akt and caspase-9 in gastric and colorectal carcinomas

The serine/threonine protein kinase B/Akt plays a central role in the coordination of multiple signal transduction processes involved in transcriptional regulation, cell survival, and apoptosis. Activation of Akt kinase is a prognostic factor in several types of cancers; however, its role in gastrointestinal cancers is not fully understood. Caspase-9 is an Akt substrate that belongs to the caspase family of proteases, which function as initiators of the mitochondrial apoptotic pathway. Little is known about the role of caspase-9 phosphorylation, which downregulates the apoptotic activity of the enzyme. In this study, we investigated the expression of phosphorylated (p)-Akt and phosphorylated (p)-caspase-9 in gastric and colorectal carcinoma and the relationship between p-Akt and p-caspase-9 expression and clinicopathological parameters of gastric and colorectal cancer patients. In total, 75 samples of advanced gastric adenocarcinoma (37 well-to-moderately differentiated and 38 poorly differentiated) and 76 samples of advanced colorectal adenocarcinoma (69 well-to-moderately differentiated and 7 poorly differentiated) were analyzed for p-Akt and p-caspase-9 expression by immunohistochemistry. Our results reveal a correlation between p-Akt and p-caspase-9 expression in gastric and colorectal cancers. Levels of p-caspase-9 were significantly higher in colorectal cancer than in gastric cancer, indicating tumor-specific regulation. Although the biological role of p-Akt/p-caspase-9 signaling remains unclear, we suggest that phosphorylation of caspase-9 may be a useful tool to assess the state of gastrointestinal cancer and the effects of anti-cancer therapy.

Immunohistochemical expression of nuclear and cytoplasmic survivin in gastrointestinal carcinoma

Survivin is a protein that is highly expressed in many embryonic tissues, as well as most human tumors. Prior studies have reported both positive and negative correlations between survivin expression and cancer prognosis, but these associations remain controversial. In the present study, we assessed the expression of nuclear and cytoplasmic survivin in gastrointestinal carcinomas. Using these data, we determined the correlation between nuclear and cytoplasmic survivin and, further, investigated correlations between survivin expression and clinicopathological parameters. Seventy-two advanced gastric adenocarcinomas and 78 colorectal adenocarcinomas were analyzed for survivin expression by immunohistochemistry. Expression of both nuclear and cytoplasmic survivin was significantly higher in colorectal carcinomas than in gastric carcinomas (P < 0.01). There was a positive correlation between nuclear and cytoplasmic expression of survivin (r = 0.42, P < 0.001). In gastric carcinomas, the level of survivin protein expression was associated with tumor differentiation, patient age, and lymphatic invasion (P < 0.05, 0.01, and 0.01, respectively). In colorectal carcinomas, the level of nuclear survivin expression was significantly higher in females than in males (P < 0.05). There were no significant associations between survivin expression and most of the clinicopathological parameters. Nevertheless, there was a trend towards an inverse correlation between nuclear survivin expression and tumor aggressiveness in gastric carcinoma; there was a similar trend for cytoplasmic survivin expression. In summary, our results suggest that levels of nuclear and cytoplasmic survivin expression differ between gastric carcinoma and colorectal carcinoma.

Immunohistochemical characterization of pyrimidine synthetic enzymes, thymidine kinase-1 and thymidylate synthase, in various types of cancer

Thymidine kinase-1 (TK-1) and thymidylate synthase (TS) are key enzymes for salvage and de novo pyrimidine synthesis, respectively. Numerous studies have suggested that increased TS levels are associated closely with resistance to fluoropyrimidine-based chemotherapy. TAS-102 is a novel drug containing trifluorothymidine, which is phosphorylated by TK-1 to its active monophosphated form, that in turn can inhibit TS. TAS-102 has been shown to exhibit antitumor activity in fluoropyrimidine-resistant human cancer cells. TAS-102 is currently undergoing clinical trials for use in gastrointestinal cancers. In the present study, we used immunohistochemistry to investigate the expression of TK-1 and TS in various types of cancer. TK-1 and TS expression was markedly different between cancer types. High TK-1 expression was detected prominently in gastrointestinal adenocarcinomas and esophageal and uterine squamous cell carcinomas. Gastrointestinal adenocarcinomas and squamous cell uterine carcinomas were often accompanied by high TS expression, indicating activation of pyrimidine synthesis through both the salvage and de novo pathways. These results led us to consider that TAS-102 may also be effective for esophageal and uterine squamous cell carcinomas, as well as for gastrointestinal adenocarcinomas, even in fluoropyrimidine-resistant cases with high TS expression. In contrast, thyroid papillary carcinomas, lung adenocarcinomas, hepatocellular carcinomas, pancreatic ductal carcinomas, and renal cell carcinomas, which exhibit low TK-1 expression, may be resistant to TAS-102. In non-small cell lung cancers, high TK-1 expression was demonstrated in squamous cell carcinomas, but not in adenocarcinomas. This result suggests that TAS-102 efficacy and the pyrimidine synthetic pathway may differ depending on histological type. Our results indicate that administration of TAS-102 could be selected on the basis of the immunohistochemical evaluation of TK-1 and TS.

Cortical representation area of human dental pulp

To elucidate the dental pulp-representing area in the human primary somatosensory cortex and the presence of A-beta fibers in dental pulp, we recorded somatosensory-evoked magnetic fields from the cortex in seven healthy persons using magnetoencephalography. Following non-painful electrical stimulation of the right maxillary first premolar dental pulp, short latency (27 ms) cortical responses on the magnetic waveforms were observed. However, no response was seen when stimulation was applied to pulpless teeth, such as devitalized teeth. The current source generating the early component of the magnetic fields was located anterior-inferiorly compared with the locations for the hand area in the primary somatosensory cortex. These results demonstrate the dental pulp representation area in the primary somatosensory cortex, and that it receives input from intradental A-beta neurons, providing a detailed organizational map of the orofacial area, by adding dental pulp to the classic "sensory homunculus".

Cortical neuromagnetic fields preceding voluntary jaw movements

Slow cortical potentials (readiness potentials, RPs) reflecting the central programming of voluntary jaw movements were reported to appear preceding the movements. However, the current source producing the RP has not yet been localized. This study aimed to determine the cortical regions involved in the central programming of bilaterally symmetrical voluntary jaw movements, by locating the current source of the neuromagnetic counterpart of the RP (readiness field, RF). The RFs were found in the fronto-lateral region bilaterally, starting around 860 and 600 ms prior to the onset of masseter and digastric electromyograms (EMGs), respectively, and gradually increasing in magnitude to the peak within 100 ms before the EMG onset. Thus, the RFs appeared long before the reported onset of the excitability increase of pyramidal tract neurons. The current sources producing the RFs were located in the precentral gyrus bilaterally, with no bilateral differences in strength. We conclude that the primary motor cortex is involved bilaterally in central programming as well as in execution of bilaterally symmetrical voluntary jaw movements.

Divergence of mobile genetic elements involved in the distribution of xenobiotic-catabolic capacity

Bacteria adapt rapidly to environmental stimuli, such as exposure to xenobiotics. Mobile genetic elements (MGEs) play a major role in such bacterial adaptation, via the dispersal of catabolic capacity; and, in fact, genes that encode the degradation enzymes for xenobiotics are often located on MGEs. The list of reported catabolic MGEs keeps growing as researchers continue to isolate and characterize xenobiotic degraders and the corresponding catabolic genes. Major catabolic MGEs include (conjugative) plasmids, transposons, and conjugative transposons. Catabolic transposons can be divided into class I elements (composite transposons) and class II elements (Tn 3 family transposons). This review includes a comprehensive list of naturally occurring discrete catabolic MGEs, together with a brief description for each. While MGEs are often rather large, genome-wide or large-scale sequence analyses have provided useful information on the whole genetic structure of MGEs, with clues to their function (transfer, maintenance, catabolism, etc.) and behavior in a complex natural environment. This review also gives an insight into MGE functions, based on the complete sequencing of several catabolic plasmids and two Pseudomonas genomes.

Troglitazone not only increases GLUT4 but also induces its translocation in rat adipocytes

Thiazolidinediones, insulin-sensitizing agents, have been reported to increase glucose uptake along with the expression of glucose transporters in adipocytes and cardiomyocytes. Recently, we have further suggested that the translocation of GLUT4 is stimulated by thiazolidinediones in L6 myocytes. However, the direct effects of thiazolidinediones on translocation of glucose transporters have not yet been determined. In this study, using hemagglutinin epitope-tagged GLUT4 (GLUT4-HA), we provide direct evidence of the effect of troglitazone on the translocation of GLUT4 in rat epididymal adipocytes. Primary cultures of rat adipocytes were transiently transfected with GLUT4-HA and overexpressed eightfold compared with endogenous GLUT4 in transfected cells. A total of 24 h of treatment with troglitazone (10(-4) mol/l) increased the cell surface level of GLUT4-HA by 1.5 +/- 0.03-fold (P < 0.01) without changing the total amount of GLUT4-HA, whereas it increased the protein level of endogenous GLUT4 (1.4-fold) without changing that of GLUT1. Thus, the direct effect on the translocation can be detected apart from the increase in endogenous GLUT4 content using GLUT4-HA. Troglitazone not only increased the translocation of GLUT4-HA on the cell surface in the basal state but also caused a leftward shift in the dose-response relations between GLUT4-HA translocation and insulin concentration in the medium (ED(50): from approximately 0.1 to 0.03 nmol/l). These effects may partly contribute to the antidiabetic activity of troglitazone in patients with obesity and type 2 diabetes.

Lack of association between hepatocyte nuclear factor-1beta gene and common forms of type 2 diabetes in the Japanese population

Mutations in the hepatocyte nuclear factor-1beta (HNF-1beta) gene have been shown to be a cause of maturity-onset diabetes of the young (MODY). We studied the contribution of the HNF-1beta gene to susceptibility to common forms of Type 2 diabetes in the genetically homogeneous Japanese population, by investigating the allelic association of Type 2 diabetes with two markers in the HNF-1beta region. The frequency of a nonsense mutation, R177X, which was previously reported in a Japanese family, was also studied by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method using a mismatch primer. A total of 200 subjects were studied. There was no significant difference in allele frequencies of either of the two polymorphisms studied between patients with Type 2 diabetes and control subjects, or between subgroups of patients subdivided by the presence of mild or severe diabetic nephropathy. None of the subjects studied had R177X mutation, giving a frequency of less than 1.1% in common forms of Type 2 diabetes in Japan. These results suggest that mutations in the HNF-1beta gene derived from a limited number of founders are not a major cause of common forms of Type 2 diabetes, even in the genetically homogeneous Japanese population.

Genetic polymorphisms and functional characterization of the 5'-flanking region of the human CYP2C9 gene: in vitro and in vivo studies

OBJECTIVE

Genetic polymorphisms were identified in the 5'-flanking region of the human CYP2C9 gene, and their effects on the phenotype were evaluated on the basis of the luciferase reporter gene assay and the in vivo pharmacokinetics of phenytoin.

METHODS

Genetic polymorphisms were screened by polymerase chain reaction-single-strand conformational polymorphism analysis, following sequencing with DNA samples obtained from 50 healthy volunteers and 133 adult epileptic patients. HepG2 hepatoma cells were cotransfected with various sequence patterns of 5'-flanking region-luciferase reporter gene constructs. Pharmacokinetic parameters of phenytoin in relation to the corresponding sequence patterns were estimated by the Bayesian method, and the results were compared with in vitro activities.

RESULTS

Genetic analysis revealed the existence of 7 single nucleotide polymorphisms (SNPs). Allele frequencies of T-->C transition at position -1912 (T-1912C), C-1886G, C-1566T, G-1538A, C-1189T, G-982A, and A-162G were 0.019, 0.019, 0.077, 0.019, 0.579, 0.019, and 0.003, respectively. Some mutations occurred simultaneously, and a total of 6 sequence patterns (patterns 1-6) were observed. The luciferase reporter gene assay indicated that the presence of mutation(s) resulted in a reduction in luciferase activity of 41.4% (pattern 2) to 86.8% (pattern 5) compared with the activity of the wild-type construct. The calculated intrinsic clearance of phenytoin was also lower (up to a 40% reduction for pattern 2) when a mutation(s) was present.

CONCLUSION

In addition to the two major mutations in the coding region (CYP2C9*2 and CYP2C9*3 ), mutations in the 5'-flanking region of the human CYP2C9 gene appear to contribute to the large interindividual variability in drug metabolism activity.

Transgenic overexpression of leptin rescues insulin resistance and diabetes in a mouse model of lipoatrophic diabetes

Lipoatrophic diabetes is caused by a deficiency of adipose tissue and is characterized by severe insulin resistance, hypoleptinemia, and hyperphagia. The A-ZIP/F-1 mouse (A-ZIPTg/+) is a model of severe lipoatrophic diabetes and is insulin resistant, hypoleptinemic, hyperphagic, and shows severe hepatic steatosis. We have also produced transgenic "skinny" mice that have hepatic overexpression of leptin (LepTg/+) and no adipocyte triglyceride stores, and are hypophagic and show increased insulin sensitivity. To explore the pathophysiological and therapeutic roles of leptin in lipoatrophic diabetes, we crossed LepTg/+ and A-ZIPTg/+ mice, producing doubly transgenic mice (LepTg/+:A-ZIPTg/+) virtually lacking adipose tissue but having greatly elevated leptin levels. The LepTg/+:A-ZIPTg/+ mice were hypophagic and showed improved hepatic steatosis. Glucose and insulin tolerance tests revealed increased insulin sensitivity, comparable to LepTg/+ mice. These effects were stable over at least 6 months of age. Pair-feeding the A-ZIPTg/+ mice to the amount of food consumed by LepTg/+:A-ZIPTg/+ mice did not improve their insulin resistance, diabetes, or hepatic steatosis, demonstrating that the beneficial effects of leptin were not due to the decreased food intake. Continuous leptin administration that elevates plasma leptin concentrations to those of LepTg/+:A-ZIPTg/+ mice also effectively improved hepatic steatosis and the disorder of glucose and lipid metabolism in A-ZIP/F-1 mice. These data demonstrate that leptin can improve the insulin resistance and diabetes of a mouse model of severe lipoatrophic diabetes, suggesting that leptin may be therapeutically useful in the long-term treatment of lipoatrophic diabetes.

Polymorphism in gene for islet autoantigen, IA-2, and type 1 diabetes in Japanese subjects

Autoantibodies against IA-2 have been detected in up to 86% of newly diagnosed patients with type 1 diabetes and appear to identify a subgroup of prediabetic subjects who rapidly progress to type 1 diabetes. We examined the association of IA-2 gene polymorphism with type 1 diabetes in Japanese subjects. A total of 276 Japanese subjects were studied for disease association and, in addition, another 53 patients were studied for association with the autoantibody status to IA-2. A microsatellite marker D2S1753E, located in the intron of the IA-2 gene, was used as a genetic marker in this study. In Japanese, two alleles (161mu and 165mu) were more frequent, and the 163mu allele was less frequent than in Caucasians (p = 0.0001). There was no significant difference in frequencies of alleles between diabetic patients and control subjects. The frequency of IA-2 gene polymorphism was not significantly different between patients stratified by age-at-onset, or between patients with and without susceptible HLA, DRB1*0405, DRB1*0802 and DRB1*0901. There was no significant difference in allele frequency of the IA-2 gene polymorphism between patients with and without autoantibody to IA-2. In conclusion, IA-2 gene polymorphism is not associated with either susceptibility to, or heterogeneity in type 1 diabetes in Japanese subjects.

Troglitazone induces GLUT4 translocation in L6 myotubes

A number of studies have demonstrated that insulin resistance in the skeletal muscle plays a pivotal role in the insulin resistance associated with obesity and type 2 diabetes. A decrease in GLUT4 translocation from the intracellular pool to the plasma membranes in skeletal muscles has been implicated as a possible cause of insulin resistance. Herein, we examined the effects of an insulin-sensitizing drug, troglitazone (TGZ), on glucose uptake and the translocation of GLUT4 in L6 myotubes. The prolonged exposure (24 h) of L6 myotubes to TGZ (10(-5) mol/l) caused a substantial increase in the 2-deoxy-[3H]D-glucose (2-DG) uptake without changing the total amount of the glucose transporters GLUT4, GLUT1, and GLUT3. The TGZ-induced 2-DG uptake was completely abolished by cytochalasin-B (10 micromol/l). The ability of TGZ to translocate GLUT4 from light microsomes to the crude plasma membranes was greater than that of insulin. Both cycloheximide treatment (3.5 x 10(-6) mol/l) and the removal of TGZ by washing reversed the 2-DG uptake to the basal level. Moreover, insulin did not enhance the TGZ-induced 2-DG uptake additively. The TGZ-induced 2-DG uptake was only partially reversed by wortmannin to 80%, and TGZ did not change the expression and the phosphorylation of protein kinase B; the expression of protein kinase C (PKC)-lambda, PKC-beta2, and PKC-zeta; or 5'AMP-activated protein kinase activity. a-Tocopherol, which has a molecular structure similar to that of TGZ, did not increase 2-DG uptake. We conclude that the glucose transport in L6 myotubes exposed to TGZ for 24 h is the result of an increased translocation of GLUT4. The present results imply that the effects of troglitazone on GLUT4 translocation may include a new mechanism for improving glucose transport in skeletal muscle.

Sequence analysis of candidate genes for common susceptibility to type 1 and type 2 diabetes in mice

Although type 1 and type 2 diabetes are regarded as clinically distinct diseases, several lines of evidence have suggested common genetic factors between the two types of diabetes. The non-obese diabetic (NOD) mouse, an animal model of type 1 diabetes, and the Nagoya-Shibata-Yasuda (NSY) mouse, a model of type 2 diabetes, are derived from the same outbred colony, Jcl:HCR, suggesting a shared susceptibility between the two types of diabetes in mice. Genetic as well as functional studies have supported the possibility that Tcf2, which encodes the transcription factor, hepatocyte nuclear factor 1beta (HNF-1beta), is a candidate gene for the common susceptibility between NSY and NOD mice. Txn, encoding thioredoxin which is a redox (reduction/oxidation)-active protein, is also a positional and functional candidate for a common susceptibility gene. To investigate whether either of these two genes is a common susceptibility gene, the coding nucleotide sequences of these two genes were compared among the NSY, NOD and control C3H strains. The coding sequence of Tcf2 of the NOD mouse was identical to that of the C3H mouse, but was different from that of the NSY mouse. The coding sequence of Txn was identical in the three strains. These data suggest that neither of the two genes is a common susceptiblity gene between type 1 and type 2 diabetes in mice.

[Pathology and significance of leptin resistance in obesity]

Leptin, the protein product of the ob gene, is predominantly secreted from white adipose tissue, and acts on the brain to regulate food intake, energy expenditure, and neuroendocrine function. Obese rodent and humans are mostly associated with high circulating leptin levels. These findings have led to the conclusion that obese individuals are relatively insensitive to endogenous leptin termed 'leptin resistance'. The potential sites for leptin resistance include the blood-brain-barrier transport system and the leptin signaling mechanism in leptin-responsive neurons in the hypothalamus. In this review, we describe leptin, leptin receptor, and potential hypothesis of leptin resistance.

Ghrelin, an endogenous growth hormone secretagogue, is a novel orexigenic peptide that antagonizes leptin action through the activation of hypothalamic neuropeptide Y/Y1 receptor pathway

Ghrelin, an endogenous ligand for growth hormone secretagogue (GHS) receptor originally isolated from the stomach, occurs in the hypothalamic arcuate nucleus and may play a role in energy homeostasis. Synthetic GHSs have activated the hypothalamic arcuate neurons containing neuropeptide Y (NPY), suggesting the involvement of NPY in some of ghrelin actions. This study was designed to elucidate the role of ghrelin in the regulation of food intake. A single intracerebroventricular (ICV) injection of ghrelin (5-5,000 ng/rat) caused a significant and dose-related increase in cumulative food intake in rats. Ghrelin (500 ng/rat) was also effective in growth hormone-deficient spontaneous dwarf rats. Hypothalamic NPY mRNA expression was increased in rats that received a single ICV injection of ghrelin (500 ng/rat) (approximately 160% of that in vehicle-treated groups, P < 0.05). The ghrelin's orexigenic effect was abolished dose-dependently by ICV co-injection of NPY Y1 receptor antagonist (10-30 microg/rat). The leptin-induced inhibition of food intake was reversed by ICV co-injection of ghrelin in a dose-dependent manner (5-500 ng/rat). Leptin reduced hypothalamic NPY mRNA expression by 35% (P < 0.05), which was abolished by ICV co-injection of ghrelin (500 ng/rat). This study provides evidence that ghrelin is an orexigenic peptide that antagonizes leptin action through the activation of hypothalamic NPY/Y1 receptor pathway.

Prognostic results of cisplatin IP and carboplatin IV with G-CSF in patients with ovarian cancer

We performed a dose-escalation study of carboplatin combined with a fixed dose of intraperitoneal cisplatin and G-CSF in patients with epithelial ovarian cancer, and analyzed the progression-free and overall survival. Six of the patients who entered the study with stage IC and II disease are still alive with no evidence of disease. The five-year survival rate was 61% for the 18 patients with stage III and IV disease; progression-free survival over 5 years was 32%. Our results show this to be an effective treatment regimen for epithelial ovarian cancer. Prognosis is good with this combined carboplatin/cisplatin/G-CSF therapy, especially for those patients with microscopic or no residual disease.

Structure-activity relationship of orally potent tripeptide-based HIV protease inhibitors containing hydroxymethylcarbonyl isostere

We designed and synthesized a new class of peptidomimetic human immunodeficiency virus protease inhibitors containing a unique unnatural amino acid, allophenylnorstatine [Apns; (2S,3S)-3-amino-2-hydroxy-4-phenylbutyric acid], with a hydroxymethylcarbonyl isostere as the active moiety. From a structure-activity relationship study of HIV-1 protease inhibition, enzyme selectivity for other aspartyl proteases, the antiviral activity and pharmacokinetics in rats, 24c (KNI-227) and 24d (KNI-272, our first clinical candidate) were found to be selective and orally potent HIV protease inhibitors. Moreover, an improvement of the pharmacokinetic features of KNI-272 provided two long-lasting and highly bioavailable compounds (24g: JE-2178, 24h: JE-2179).

Age-related association of MHC class I chain-related gene A (MICA) with type 1 (insulin-dependent) diabetes mellitus

To assess the contribution of the HLA class I region to susceptibility to and heterogeneity of type 1 diabetes, we investigated the association of polymorphism of MHC class I chain-related gene A (MICA) with age-at-onset as well as susceptibility to type 1 diabetes. One hundred one Japanese patients and 110 healthy control subjects were studied. The frequency of A4 allele was significantly higher and that of A6 allele was significantly lower in patients than in control subjects. The frequency of A5.1 allele was highest in early-onset patients (23.0%), intermediate in intermediate-onset patients (9.2%) and lowest in late-onset patients (7.7%) (trend chi-squared test, p = 0.0098). A5. 1 allele was strongly associated with HLA-B7 and Cw7, suggesting that MICA*A5.1-B7-Cw7 haplotype contains a gene responsible for age-at-onset. A4 allele was associated with a susceptible haplotype, DR4-DQB1*0401, and A6 allele was associated with a protective haplotype, DR2-DQB1*0601, suggesting that the association of MICA with type 1 diabetes susceptibility may be due to linkage disequilibrium with class II haplotypes. These data suggest that MICA gene is associated with age-at-onset and that a gene (or genes) responsible for age-at-onset of type 1 diabetes is located in the HLA class I region, probably near the region of MICA-B-C.

Comparative evaluation of conjugate vaccines in the Haemophilus influenzae infection model

We used a murine model of Haemophilus influenzae type b (Hib) infection to analyze the immunologic response to two commercially available PRP conjugate vaccines (HbOC, PRP-T). The mortality rate in mice infected with a large dose of the bacteria after vaccination with HbOC or PRP-T at two and three doses was significantly lower than in non-vaccinated mice and mice vaccinated by one dose. Furthermore, for infections caused by a small bacterial dose, the mortality rate in mice vaccinated with one, two, or three doses was significantly lower than in non-vaccinated mice. The induction level of anti-PRP antibodies, especially IgG, in serum of mice vaccinated by two or three doses was higher than in those vaccinated with a single dose. Our results indicate that the dose of vaccine influences its efficacy in protecting against Hib infection. Our results also showed a lack of difference between two different PRP conjugate vaccines.

Downregulation of leptin by free fatty acids in rat adipocytes: effects of triacsin C, palmitate, and 2-bromopalmitate

Free fatty acid (FFA) has been reported to decrease leptin mRNA levels in 3T3-L1 adipocytes. When using this cell line, it is difficult to determine the protein levels because a very small amount of leptin is secreted into the medium. The effect of FFA on leptin secretion from adipocytes has not yet been determined. In addition, in vivo studies have failed to demonstrate a FFA-induced decrease in plasma leptin levels. To clarify the effect of FFA on leptin production, we investigated the leptin protein level in the medium and the mRNA level in primary cultured rat adipocytes treated with triacsin C, which is a potent inhibitor of acyl-coenzyme A (CoA) synthetase, palmitate, and 2-bromopalmitate. Triacsin C (0 to 5 x 10(-5) mol/L) decreased leptin concentrations in the culture medium in a dose-dependent manner. Leptin mRNA levels were decreased to 10% of the control in the presence of triacsin C. The concentration of triacsin C needed to suppress leptin production was similar to the Ki value (approximately 10(-5) mol/L) for inhibition of acyl-CoA synthetase. Both palmitate and 2-bromopalmitate decreased leptin concentra-tions but did not affect the triacsin C-induced decrease in leptin additively. In conclusion, both protein and mRNA levels of leptin were decreased by triacsin C and FFA in primary cultured rat adipocytes. Our findings suggest that FFA is involved in the regulation of leptin production in adipocytes.

[Insulin resistance, role of leptin and leptin receptor]

Leptin, the obese gene product, is an adipocyte-derived satiety factor which is involved in the regulation of food intake and energy expenditure. Obesity often accompanies insulin resistance and high levels of leptin. In in vitro studies, leptin has been reported to increase fatty acid oxidation and decrease fatty acid synthesis in adipocytes and hepatocytes. The direct effects of leptin on glucose metabolism and insulin signaling have not been clarified yet. In in vivo studies, however, leptin has been reported to improve insulin sensitivity and glucose metabolism in normal and obese rodents acting mainly through hypothalamus. Moreover leptin has been reported to have antidiabetic effects in insulin-deficient diabetes rats and lipoatrophic diabetes mice. It is suggested that leptin modulates insulin sensitivity and glucose disposal and that leptin may have a pathophysiological and therapeutic implications in diabetes.

Thyrotropin decreases leptin production in rat adipocytes

Leptin, which is secreted from adipocytes, has a role in the regulation of appetite and energy expenditure. The thyrotropin receptor (TSH-R) was recently found in adipocytes. We examined the effects of TSH on leptin production and lipolysis in rat epididymal adipocytes. TSH decreased the concentration of leptin in the medium time (approximately 24 hours)- and dose (approximately 10(-7) mol/L)-dependently (half-maximal inhibition [IC50] approximately 10(-9) mol/L). TSH also decreased the ob mRNA level approximately 55% in adipocytes. We confirmed the presence of TSH-R mRNA in the adipocytes by reverse transcription-polymerase chain reaction (RT-PCR). TSH stimulated glycerol release dose-dependently (IC50 approximately 10(-8) mol/L) in adipocytes. This TSH-induced glycerol release was further enhanced by adenosine deaminase (ADA). In summary, TSH reduced leptin production and stimulated lipolysis in rat epididymal adipocytes. Although the pathophysiological relevance of the regulation of leptin production and lipolysis by TSH is unknown, we speculate that TSH may affect the regulation of appetite and energy expenditure in pathophysiological states.

Abnormal blinking of newscasters

When compared with a control group, blink rates of Japanese TV newscasters were increased, suggesting a possible reaction to reading the news under stressful studio conditions. Frequent blinking may be distractive to the viewing audience.

JE-2147: a dipeptide protease inhibitor (PI) that potently inhibits multi-PI-resistant HIV-1

We designed, synthesized, and identified JE-2147, an allophenylnorstatine-containing dipeptide HIV protease inhibitor (PI), which is potent against a wide spectrum of HIV-1, HIV-2, simian immunodeficiency virus, and various clinical HIV-1 strains in vitro. Drug-resistant clinical HIV-1 strains, isolated from seven patients who had failed 9-11 different anti-HIV therapeutics after 32-83 months, had a variety of drug-resistance-related amino acid substitutions and were highly and invariably resistant to all of the currently available anti-HIV agents. JE-2147 was, however, extremely potent against all such drug-resistant strains, with IC(50) values ranging from 13-41 nM (<2-fold changes in IC(50) compared with that of wild-type HIV-1). The emergence of JE-2147-resistant HIV-1 variants in vitro was substantially delayed compared with that of HIV-1 resistant to another allophenylnorstatine-containing compound, KNI-272, and other related PIs. Structural analysis revealed that the presence of a flexible P2' moiety is important for the potency of JE-2147 toward wild-type and mutant viruses. These data suggest that the use of flexible components may open a new avenue for designing PIs that resist the emergence of PI-resistant HIV-1. Further development of JE-2147 for treating patients harboring multi-PI-resistant HIV-1 is warranted.

Association of plasma fibrinogen level and blood pressure with diabetic retinopathy, and renal complications associated with proliferative diabetic retinopathy, in Type 2 diabetes mellitus

AIM

To clarify the association of several clinical parameters, including plasma fibrinogen level, with diabetic retinopathy in patients with Type 2 diabetes mellitus (DM).

METHODS

A total of 294 Japanese patients with Type 2DM were studied; 53 patients with no diabetic retinopathy (NDR), 90 with background diabetic retinopathy (BDR), and 151 with proliferative diabetic retinopathy (PDR). Multiple logistic regression analysis was performed to assess variables independently associated with diabetic retinopathy in two settings: presence of retinopathy of any severity and presence of advanced retinopathy.

RESULTS

The following parameters were identified as independent factors associated with the presence of diabetic retinopathy (NDR vs. BDR + PDR): type of therapy (P<0.0005), log-transformed plasma fibrinogen level (P < 0.05), mean blood pressure (P < 0.05), and duration of diabetes (P < 0.05). The independent variables associated with advanced retinopathy were type of therapy (P<0.00005), age (P<0.0005) and nephropathy (P<0.05). Body mass index, smoking and hypertensive status, HbA1c and total cholesterol levels were not independently associated.

CONCLUSIONS

These data suggest that in patients with Type 2 DM, an increased blood viscosity due to high fibrinogen level as well as an elevated intravessel pressure play a role in the development of diabetic retinopathy, and that the progression to PDR is influenced or accompanied by the deterioration of renal status.

A dose-finding study of nedaplatin and cyclophosphamide for patients with gynecological malignancies

BACKGROUND

Nedaplatin is a new analogue of cisplatin with similar efficacy but less renal toxicity. We investigated the appropriate dose of nedaplatin in combination with cyclophosphamide for patients with gynecological malignancies.

METHODS

Nine patients (five with ovarian cancer and four with uterine cervical cancer) were studied. Three patients received 60 mg/m2 of nedaplatin combined with 500 mg/m2 of cyclophosphamide every 4 weeks. Another three patients were each administered 80 or 100 mg/m2 of nedaplatin with the same dose of cyclophosphamide. A total of 27 courses was given.

RESULTS

No patient needed dose reduction due to myelosuppression and no severe adverse events were observed.

CONCLUSIONS

Treatment with 100 mg/m2 of nedaplatin and 500 mg/m2 of cyclophosphamide is feasible for patients with gynecological malignancies. However, phase II studies are needed to clarify the efficacy of this combination chemotherapy.

Down regulation of peroxisome proliferator-activated receptorgamma expression by inflammatory cytokines and its reversal by thiazolidinediones

AIMS/HYPOTHESIS

Previous studies show that inflammatory cytokines play a part in the development of insulin resistance. Thiazolidinediones were developed as insulin-sensitizing drugs and are ligands for the peroxisome proliferator-activated receptory (PPARgamma). We hypothesized that the anti-diabetic mechanism of thiazolidinediones depends on the quantity of PPARgamma in the insulin resistant state in which inflammatory cytokines play a part.

METHODS

We isolated rat PPARgamma1 and gamma2 cDNAs and examined effects of various cytokines and thiazolidinediones on PPARgamma mRNA expression in rat mature adipocytes.

RESULTS

Various inflammatory cytokines, such as tumour necrosis factor-alpha (TNF-alpha), interleukin-1alpha (IL-1alpha), IL-1beta, IL-6 and leukaemia inhibitory factor decreased PPARgamma mRNA expression. In addition, hydrogen peroxide, lysophosphatidylcholine or phorbol 12-myristate 13-acetate also decreased the expression of PPARgamma. The suppression of PPARgamma mRNA expression caused by 10 nmol/l of TNF-alpha was reversed 60% and 55% by treatment with 10(-4) mol/l of troglitazone and 10(-4) mol/l of pioglitazone, respectively. The suppression of glucose transporter 4 mRNA expression caused by TNF-alpha was also reversed by thiazolidinediones. Associated with the change of PPARgamma mRNA expression, troglitazone improved glucose uptake suppressed by TNF-alpha.

CONCLUSION/INTERPRETATION

Our study suggests that inflammatory cytokines could be factors that regulate PPARgamma expression for possible modulation of insulin resistance. In addition, we speculate that the regulation of PPARgamma mRNA expression may contribute to the anti-diabetic mechanism of thiazolidinediones.

Structure-activity relationship of small-sized HIV protease inhibitors containing allophenylnorstatine

We designed and synthesized a new class of peptidomimetic human immunodeficiency virus (HIV) protease inhibitors containing a unique unnatural amino acid, allophenylnorstatine [Apns; (2S, 3S)-3-amino-2-hydroxy-4-phenylbutyric acid], with a hydroxymethylcarbonyl (HMC) isostere as the active moiety. A systematic evaluation of structure-activity relationships for HIV protease inhibition, anti-HIV activities, and pharmacokinetic profiles has led to the delineation of a set of structural charateristics that appear to afford an orally available HIV protease inhibitor. Optimum structures, exemplified by 21f (JE-2147), incorporated 3-hydroxy-2-methylbenzoyl groups as the P2 ligand, (R)-5,5-dimethyl-1,3-thiazolidine-4-carbonyl (Dmt) residue at the P1' site, and 2-methylbenzylcarboxamide group as the P2' ligand. The present study demonstrated that JE-2147 has potent antiviral activities in vitro and exhibits good oral bioavailability and plasma pharmacokinetic profiles in two species of laboratory animals.

A phase I study of cisplatin i.p. and carboplatin i.v. with G-CSF in patients with ovarian cancer

We conducted a dose-escalation study with a fixed dose of intraperitoneal cisplatin and G-CSF support of carboplatin using the Calvert formula in epithelial ovarian cancer. Twenty-five patients were entered in this study. On day 1, carboplatin was administered intravenously at target AUCs of 4, 5, 6, and 7. On day 2, cisplatin was given i.p. in 70 mg/m2. G-CSF, 50 microgram/m2, was administered subcutaneously from day 7 to 16. Cycles were scheduled to be delivered every four weeks. A total of 85 cycles were administered. The maximum tolerated dose was AUC 7 mg/ml x min of carboplatin. The overall response rate was 80% (12/15). The combination in this regimen is feasible, and a phase II study of this regimen is warranted.

A phase I trial of the pharmacokinetics, toxicity, and activity of KNI-272, an inhibitor of HIV-1 protease, in patients with AIDS or symptomatic HIV infection

The pharmacokinetics, toxicity, and activity of KNI-272, a transition state inhibitor of HIV-1 protease, was assessed in a phase I trial. After an initial phase in which the pharmacokinetics were assessed, 37 patients with AIDS or symptomatic HIV infection and 100-400 CD4 cells/mm3 were entered in an escalating dose study. KNI-272 was administered four times daily for up to 12 weeks. Oral bioavailability ranged from 22 to 55% and was not appreciably different in the fasting and post-prandial state. The dose limiting toxicity was hepatic transaminase elevation; this could be reduced by escalating the dose over 4 weeks. When administered this way, the maximum tolerated oral dose was 40 mg/kg per day. At the highest two tolerated doses (26.4 and 40 mg/kg per day), there was some evidence of an anti-HIV effect with median decreases of 0.2-0.3 log10 copies/ml plasma HIV RNA; these decreases persisted through 7-8 weeks of treatment. There was an upward trend in the CD4 count at the 40 mg/kg per day dose but not at other doses. Additional studies focused on approaches to improve the therapeutic index of KNI-272 may be warranted.

Hepatocyte nuclear factor-1alpha gene and non-insulin-dependent diabetes mellitus in the Japanese population

Recently, hepatocyte nuclear factor-1alpha(HNF-1alpha, which is encoded by the TCF1 gene) mutations were reported in a subset of patients with maturity onset diabetes of the young (MODY3). We studied the contribution of TCF1 to genetic susceptibility to common non-insulin-dependent diabetes mellitus (type 2) in Japanese subjects by investigating allelic association with type 2 diabetes use of three markers. We also studied the frequency of the G191D mutation, the only mutation of TCF1 reported so far in late-onset type 2 diabetes. A total of 356 subjects were studied. There were no significant differences in allele frequency of the three markers between patients with type 2 diabetes and control subjects. A G191D mutation was not found in the subjects studied, giving a frequency of less than 0.4% in common type 2 diabetes. The lack of association of type 2 diabetes with three markers in and near TCF1 suggests that mutations in TCF1 derived from a limited number of founders are not a major cause of common type 2 diabetes even in the genetically homogeneous Japanese population. The data also indicate that the G191D mutation in TCF1 plays little, if any, role in susceptibility to common type 2 diabetes in the Japanese.

Asp905Tyr polymorphism of the gene for the skeletal muscle-specific glycogen-targeting subunit of protein phosphatase 1 in NIDDM

OBJECTIVE

To clarify the contribution of the Asp905Tyr polymorphism of the muscle-specific glycogen-targeting subunit of protein phosphatase 1 (PP1G) to insulin resistance and related diseases.

RESEARCH DESIGN AND METHODS

We investigated the Asp905Tyr polymorphism of the PPP1R3 gene, which encodes the muscle-specific glycogen-targeting subunit of PP1G, in 259 Japanese patients with NIDDM and 194 healthy control subjects.

RESULTS

No significant difference was found in the genotype distribution between NIDDM patients (N = 259; Asp/Asp = 0.10, Asp/Tyr = 0.44, Tyr/Try = 0.46) and healthy control subjects (n = 194; Asp/Asp = 0.13, Asp/Tyr = 0.37, Tyr/Tyr = 0.50) or between patient groups subdivided by the mode of treatment: NIDDM patients with insulin therapy (Asp/Asp = 0.14, Asp/Tyr = 0.46, Tyr/Tyr = 0.40) and those without insulin therapy (Asp/Asp = 0.07, Asp/Tyr = 0.43, Tyr/Tyr = 0.50). However, NIDDM patients with the Tyr allele, which was previously reported to be associated with insulin resistance, tended to have lower BMIs than those without this allele (Asp/Asp: 24.5 +/- 1.1 kg/m2, Asp/Tyr: 22.6 +/- 0.4 kg/m2, Tyr/Tyr: 22.8 + 0.3 kg/m2, P = 0.06 by analysis of variance).

CONCLUSIONS

These data suggest that the Asp905Tyr polymorphism of the PPP1R3 gene is not associated with NIDDM or high BMI, both of which are known to be insulin-resistant states, in the Japanese population.