Cerulenin, an inhibitor of protein acylation, selectively attenuates nutrient stimulation of insulin release: a study in rat pancreatic islets

Nutrients such as glucose stimulate insulin release from pancreatic beta-cells through both ATP-sensitive K+ channel-independent and -dependent mechanisms, which are most likely interrelated. Although little is known of the molecular basis of ATP-sensitive K+ channel-independent insulinotropic nutrient actions, mediation by cytosolic long-chain acyl-CoA has been implicated. Because protein acylation might be a sequel of cytosolic long-chain acyl-CoA accumulation, we examined if this reaction is engaged in nutrient stimulation of insulin release, using cerulenin, an inhibitor of protein acylation. In isolated rat pancreatic islets, cerulenin inhibited the glucose augmentation of Ca2+-stimulated insulin release evoked by a depolarizing concentration of K+ in the presence of diazoxide and Ca2+-independent insulin release triggered by a combination of forskolin and phorbol ester under stringent Ca2+-free conditions. Cerulenin inhibition of glucose effects was concentration dependent, with a 50% inhibitory concentration (IC50) of 5 microg/ml and complete inhibition at 100 microg/ml. Cerulenin also inhibited augmentation of insulin release by alpha-ketoisocaproate, a mitochondrial fuel. Furthermore, cerulenin abolished augmentation of both Ca2+-stimulated and Ca2+-independent insulin release by 10 micromol/l palmitate, which causes palmitoylation of cellular proteins. In contrast, cerulenin did not attenuate insulin release elicited by nonnutrient secretagogues, such as a depolarizing concentration of K+, activators of protein kinases A and C, and mastoparan. Glucose oxidation, ATP content in islets, and palmitate oxidation were not affected by cerulenin. In conclusion, cerulenin inhibits nutrient augmentation of insulin release with a high selectivity. The finding is consistent with a prominent role of protein acylation in the process of beta-cell nutrient sensing.     

Overexpression of the aldo-keto reductase family protein AKR1B10 is highly correlated with smokers' non-small cell lung carcinomas.

PURPOSE: Squamous cell carcinoma (SCC) and adenocarcinoma of the lung are currently subject to similar treatment regimens despite distinct differences in histology and epidemiology. The aim of this study is to identify a molecular target with diagnostic and therapeutic values for SCC. EXPERIMENTAL DESIGN: Genes specifically up-regulated in SCC were explored through microarray analysis of 5 SCCs, 5 adenocarcinomas, 10 small cell lung carcinomas, 27 normal tissues, and 40 cancer cell lines. Clinical usefulness of these genes was subsequently examined mainly by immunohistochemical analysis. RESULTS: Seven genes, including aldo-keto reductase family 1, member B10 (AKR1B10), were identified as SCC-specific genes. AKR1B10 was further examined by immunohistochemical analysis of 101 non-small cell lung carcinomas (NSCLC) and its overexpression was observed in 27 of 32 (84.4%) SCCs and 19 of 65 (29.2%) adenocarcinomas. Multiple regression analysis showed that smoking was an independent variable responsible for AKR1B10 overexpression in NSCLCs (P < 0.01) and adenocarcinomas (P < 0.01). AKR1B10 staining was occasionally observed even in squamous metaplasia, a precancerous lesion of SCC. CONCLUSION: AKR1B10 was overexpressed in most cases with SCC, which is closely associated with smoking, and many adenocarcinoma cases of smokers. These results suggest that AKR1B10 is a potential diagnostic marker specific to smokers' NSCLCs and might be involved in tobacco-related carcinogenesis.     

Hypoxic status in ovarian serous and mucinous tumors: relationship between histological characteristics and HIF-1α/GLUT-1 expression

Material and methods We analyzed the expression of hypoxia inducible factor-1α (HIF-1α) and glucose transporter-1 (GLUT-1) by immunohistochemistry in ovarian serous and mucinous tumors from the point view of the histological characteristics and acquisition of malignancy. A total of 102 ovarian tumors were examined, composed of 31 adenomas (serous 17 and mucinous 14), 32 borderline tumors (serous 13 and mucinous 19), and 39 adenocarcinomas (serous 21 and mucinous 18). Results The overall positive ratios were as follows: HIF-1α, 74% of adenomas, 91% of borderline tumors, and 100% of adenocarcinomas; and GLUT-1, 68% of adenomas, 95% of borderline tumors, and 100% of adenocarcinomas. Comparing serous tumors and mucinous tumors, there was no significant difference in the positive ratios of HIF-1α and GLUT-1 of adenomas, borderline tumors, and adenocarcinomas. However, both markers were more strongly expressed in serous adenocarcinomas (HIF-1α, 3 + 100%; GLUT-1, 3 + 76%) than in mucinous adenocarcinomas (HIF-1α, 3 + 61%; GLUT-1, 3 + 28%). The results of immunoblotting and mRNA expression level analyses corresponded with those of immunohistochemical expression profiles. DNA binding assay also demonstrated that HIF-1 is more commonly activated in serous adenocarcinomas than in mucinous adenocarcinomas. Conclusion HIF-1α and GLUT-1 expressions seemed to be coordinated to adapt ovarian tumor cells into hypoxic conditions in close association with the acquisition of malignancy. We consider that the relatively strong expression of both markers in serous tumors compared with mucinous tumors is related to the difference in their histological characteristics.     

Two single nucleotide polymorphisms in <Emphasis Type="Italic">PRDM9</Emphasis> (<Emphasis Type="Italic">MEISETZ</Emphasis>) gene may be a genetic risk factor for Japanese patients with azoospermia by meiotic arrest

Purpose

To investigate whether defects in human PRDM9, CDK2 and PSMC3IP are associated with azoospermia Mutational analysis was performed in Japanese patients with azoospermia caused by meiotic arrest.

Methods

Mutational screening of the coding regions of human PRDM9, CDK2 and PSMC3IP was done by direct sequencing using genomic DNA from 18 Japanese patients. Statistical analysis of the detected coding single nucleotide polymorphisms (cSNPs) in patients and normal control men was then carried out.

Results

One cSNP was detected in CDK2 and PSMC3IP. There were no significant differences in genotype distribution and allele frequencies between the patient and control groups in these two genes. However, three novel cSNPs were detected in the PRDM9. The genotype and allele frequencies of heterozygotes in SNP2 and SNP3 of PRDM9 were significantly higher in the patient group than in the control group.

Conclusion

We found a possible association between PRDM9 and azoospermia by meiotic arrest.

     

CT diagnosis of primary Budd-Chiari syndrome--membranous obstruction of the inferior vena cava

Five cases with primary Budd-Chiari syndrome due to membranous obstruction of the hepatic segment of the inferior vena cava were examined by CT. In all cases, CT demonstrated caudate lobe enlargement, reticular low density within the liver parenchyma, splenomegaly, and collaterals via the ascending lumbar veins and azygous system. Pathological study revealed liver cirrhosis or fibrosis in all cases. In two cases, calcification was shown in the region of the hepatic segment of the inferior vena cava. Our results suggested that the CT appearance of primary Budd-Chiari syndrome was rather characteristic and useful in diagnosis, although membranous obliteration could not be shown directly on CT.     

Chemosensitivity test for bladder cancer in a nude-mice experimental system

The in vivo chemosensitivity test for bladder cancer, using the human bladder cancer xenografts (BT-8 and BT-11 strains) in nude mice (BALB/c) and the BBN-BT-1 bladder cancer strain in BALB/c hetero-mouse which was induced by peroral long-period administration of N-butyl-N-(4-hydroxybutyl) nitrosamine and transplantable into the subcutaneous of mouse, were examined especially in respect to the difference of chemosensitivity between young and old straining and the prospective propriety for clinical application. The subrenal capsule assay (SRC), was also compared with subcutaneous transplantation. Cis-diamminedichloroplatinum (II) and 5-FU were effective for all three strains and adriamycin and cyclophosphamide were effective for the BT-8 and BT-11 strains. Bleomycin, peplomycin and vinca alkaloids were more effective for the BT-11 strain than the BT-8 strain. The chemosensitivity of several anti-cancer drugs for the young BT-8 and BT-11 strains was almost equal to that of the old. A 68-year-old male with bladder cancer metastasized to lung and lymph nodes, whose primary tumor was transplanted to mice and established as the BT-11 strain in 1980, was treated with the VPM-CisCF combination chemotherapy which was evaluated as an effective therapy for this strain experimentally, and responded well to this therapy. As in this case, the results of nude mice experiments are valuable in clinical application. The chemosensitivity test in vivo for individual primary tumors should be done by SRC, and in SRC nude mice should be used instead of conventional mice until immunoreactive rejection can be prevented.