Functional differences between wild‐type and mutant‐type BRCA1‐associated protein 1 tumor suppressor against malignant mesothelioma cells

Malignant mesothelioma (MM) shows inactivation of the BRCA1‐associated protein 1 (BAP1) gene. In this study, we found BAP1 mutations in 5 (26%) of the 19 cell lines that we established from Japanese MM patients, and examined functional differences between the WT and mutant BAP1. First, we studied the subcellular localization of BAP1, demonstrating that the WT primarily resides in the nucleus and that the mutant BAP1 is found in the cytoplasm of the cells. Transduction of the WT BAP1 vector into MM cells with homozygous deletion at the BAP1 3′ side resulted in both inhibition of cell proliferation and anchorage‐independent cell growth, whereas BAP1 mutants of a missense or C‐terminal truncated form showed impaired growth inhibitory effects. Next, we studied how BAP1 is involved in MM cell survival after irradiation (IR), which causes DNA damage. After IR, we found that both WT and mutant BAP1 were similarly phosphorylated and phospho‐BAP1 localized mainly in the nucleus. Interestingly, BRCA1 proteins were decreased in the MM cells with BAP1 deletion, and transduction of the mutants as well as WT BAP1 increased BRCA1 proteins, suggesting that BAP1 may promote DNA repair partly through stabilizing BRCA1. Furthermore, using the MM cells with BAP1 deletion, we found that WT BAP1, and even a missense mutant, conferred a higher survival rate after IR compared to the control vector. Our results suggested that, whereas WT BAP1 suppresses MM cell proliferation and restores cell survival after IR damage, some mutant BAP1 may also moderately retain these functions.     

Pharmacokinetics of Gefitinib in a Patient with Non-Small Cell Lung Cancer Undergoing Continuous Ambulatory Peritoneal Dialysis

A 72-year-old man undergoing continuous ambulatory peritoneal dialysis (CAPD) for chronic renal failure and who had undergone right upper lobectomy for lung adenocarcinoma (pT2aN0M0) 2 years ago was admitted for recurrence of lung cancer presenting as multiple brain metastases. An epidermal growth factor receptor mutation analysis of his lung cancer revealed a deletion of 15 nucleotides (E746-A750) in exon 19. After whole-brain radiotherapy, we started daily administration of 250 mg gefitinib under the continuation of CAPD and performed a pharmacokinetic analysis. We speculated that the plasma concentration of gefitinib reached the steady state at least by day 16 after the start of gefitinib (626.6 ng/ml at trough level). On day 46, the plasma concentration was 538.4 ng/ml at trough level and the concentration in the peritoneal dialysis fluid was 34.6 ng/ml, suggesting that CAPD appeared to have little effect on the pharmacokinetics of gefitinib. During gefitinib therapy, there were no significant adverse events except for grade 2 diarrhea. Gefitinib could be safely administered to a patient undergoing CAPD.Key Words: Gefitinib, Continuous ambulatory peritoneal dialysis, Chronic renal failure, Epidermal growth factor receptor, Non-small cell lung cancer     

Synthesis of triazole- and tetrazole-xyloside analogues as potent hyaluronidase inhibitors

Hyaluronidase is one of the most important enzymes in the development of many diseases. In this study, a series of xyloside analogues bearing a triazole and tetrazole at the anomeric position were prepared from xylosylthioureas and evaluated their inhibitory effects on the hyaluronidase. Triazole and tetrazole skeletons were formed via the Hg(OAc)₂-mediated desulfurizative cyclization through carbodiimide intermediates. According to in vitro anti-hyaluronidase assay, tetrazole-xylosides having p-chloro- or p-nitro-substitution exhibited the high inhibition rates, whereas the compound having p-trifluoromethyl group on the structure did not show the potency. Our results demonstrated the importance of tetrazole-xylosides as hyaluronidase inhibitors.     

The effect of reaction temperature for nephelometric assays for rheumatoid factor

Even using the same assay parameter, reagent and calibrator (N-latex RF kit II), the results of the assay for serum rheumatoid factors (RFs) with the Behring Nephelometer Analyzer (BNA) were higher than those with the Behring Nephelometer II Analyzer (BNII) ([BNII]=0.76 [BNA]-5.7 kIU/l, r=0.997, Sy/x=60.73, n=99). The mean bias (BNA minus BNII)+/-S.D. was 52.7+/-85.5 using the Bland and Altman plot method, and the bias was not constant. The only difference in the assay condition with the two methods was the reaction temperature with the BNA being performed at room temperature (25+/-1 degrees C) and the BNII being performed at 37 degrees C. The ratio of the results with the BNII to the BNA (BNII/BNA) ranged from 0.23 to 1.18. A significant difference was observed in the BNII/BNA ratio in patients with high levels of C-reactive protein (CRP) over 2.0 mg/l (mean BNII/BNA ratio; 0.78) in comparison to patients with normal CRP levels under 2.0 mg/l (mean BNII/BNA ratio; 0.65) (P<0.01). The RF concentrations with the BNA were reduced by addition of urea, which has been used as a mild protein-denaturing agent, and there was a significant correlation between the values calculated as (1-value treated with urea/original value without urea)x100 and the BNII/BNA ratio (r=0.652, P<0.01). These data suggested that the bias between the RF values obtained by the BNA and BNII might be caused by the variation in the reactivity of autoantibodies, which might be decreased in some inflammatory diseases.     

Intratumoral ethanol injection for malignant tracheobronchial lesions: a new bronchofiberscopic procedure

We performed intratumoral ethanol injection via a flexible bronchofiberscope in 13 patients with malignant tracheobronchial lesions in order to evaluate its effects on airway dilatation and hemostasis. The results obtained are described below. Immediately after intratumoral injection of ethanol, bronchofiberscopic findings revealed that the tumor turned faintly white, there was a little regression of tumor, and a promising effect was demonstrated on patients with bleeding from tumors. The injected tumor turned necrotic within several days, and histological examination revealed no viable tumor cells in necrotic tissues. The histological anti-tumor effect of ethanol was also demonstrated in experiments with nude mice. This endoscopic treatment was very effective in polypoid tumor protruding into the tracheobronchial lumen, but ineffective in the case of compressed stenosis or obstruction. In conclusion, intratumoral injection of ethanol is considered to be a promising endoscopic treatment for malignant tracheobronchial lesions.