Stimulation of transit-peptide release and ATP hydrolysis by a cochaperone during protein import into chloroplasts

Three components of the chloroplast protein translocon, Tic110, Hsp93 (ClpC), and Tic40, have been shown to be important for protein translocation across the inner envelope membrane into the stroma. We show the molecular interactions among these three components that facilitate processing and translocation of precursor proteins. Transit-peptide binding by Tic110 recruits Tic40 binding to Tic110, which in turn causes the release of transit peptides from Tic110, freeing the transit peptides for processing. The Tic40 C-terminal domain, which is homologous to the C terminus of cochaperones Sti1p/Hop and Hip but with no known function, stimulates adenosine triphosphate hydrolysis by Hsp93. Hsp93 dissociates from Tic40 in the presence of adenosine diphosphate, suggesting that Tic40 functions as an adenosine triphosphatase activation protein for Hsp93. Our data suggest that chloroplasts have evolved the Tic40 cochaperone to increase the efficiency of precursor processing and translocation

Clinical benefit of readministration of gefitinib for initial gefitinib-responders with non-small cell lung cancer

BACKGROUND: Gefitinib, an oral agent of epidermal growth factor receptor tyrosine kinase inhibitor, has a certain efficacy against non-small cell lung cancer (NSCLC). Several predictive factors of gefitinib sensitivity have been well described. However, few studies have investigated the clinical features of gefitinib-responders. In the present study, we analyzed the response and disease progression of primary and metastatic lesions to gefitinib in responders and the results of gefitinib readministration following temporary cessation of gefitinib upon progression of initial gefitinib treatment and other treatments. METHOD: We retrospectively evaluated the clinical courses of 27 NSCLC patients who received gefitinib and achieved either a complete or partial response. RESULTS: The best-response rate and disease-control rate against the initial chemotherapy for the gefitinib-responders were 27.3% and 77.3%, respectively. Favorable efficacy was observed in the primary lesion and metastases to the lung, liver and brain, while there was no obvious effect on bone metastasis. The primary lesion and intrapulmonary metastasis were the sites of major recurrence. Median progression-free survival was 13.8 months, median duration of gefitinib treatment was 17.0 months and median overall survival was 29.2 months. Some of the patients who experienced disease progression after responding to gefitinib were again sensitive to readministration of gefitinib following temporary cessation of gefitinib and other treatments. CONCLUSION: Patients may still be expected to have prolonged survival if they once responded to gefitinib and then underwent various subsequent treatments followed by readministration of gefitinib. These findings might provide valuable information for the management of gefitinib-responders

Clinical benefit of readministration of gefitinib for initial gefitinib-responders with non-small cell lung cancer

BACKGROUND: Gefitinib, an oral agent of epidermal growth factor receptor tyrosine kinase inhibitor, has a certain efficacy against non-small cell lung cancer (NSCLC). Several predictive factors of gefitinib sensitivity have been well described. However, few studies have investigated the clinical features of gefitinib-responders. In the present study, we analyzed the response and disease progression of primary and metastatic lesions to gefitinib in responders and the results of gefitinib readministration following temporary cessation of gefitinib upon progression of initial gefitinib treatment and other treatments. METHOD: We retrospectively evaluated the clinical courses of 27 NSCLC patients who received gefitinib and achieved either a complete or partial response. RESULTS: The best-response rate and disease-control rate against the initial chemotherapy for the gefitinib-responders were 27.3% and 77.3%, respectively. Favorable efficacy was observed in the primary lesion and metastases to the lung, liver and brain, while there was no obvious effect on bone metastasis. The primary lesion and intrapulmonary metastasis were the sites of major recurrence. Median progression-free survival was 13.8 months, median duration of gefitinib treatment was 17.0 months and median overall survival was 29.2 months. Some of the patients who experienced disease progression after responding to gefitinib were again sensitive to readministration of gefitinib following temporary cessation of gefitinib and other treatments. CONCLUSION: Patients may still be expected to have prolonged survival if they once responded to gefitinib and then underwent various subsequent treatments followed by readministration of gefitinib. These findings might provide valuable information for the management of gefitinib-responders

Development of anionic bubble lipopolyplexes for efficient and safe gene transfection with ultrasound exposure in mice

Anionic bubble lipopolyplexes have been developed as anionic ultrasound (US)-responsive gene delivery carriers with biocompatible compounds for efficient and safe transfection in mice. The particles of the anionic bubble lipopolyplexes were approximately 450-600 nm with an anionic surface charge. In the absence of US exposure, the bubble lipopolyplexes showed extremely low gene expression in the human vascular endothelial cell line EAhy926. The anionic bubble lipopolyplexes, however, delivered pDNA into cells without endocytosis and showed markedly high gene expression following US exposure. The anionic bubble lipopolyplexes showed little cytotoxicity in EAhy926 cells and little aggregation with erythrocytes. Following intravenous administration into mice, the anionic bubble lipopolyplexes showed high levels of gene expression in the liver, kidney, and spleen only after US exposure to the abdominal area. The level of gene expression in liver non-parenchymal cells was significantly higher than that in parenchymal cells. In addition, the anionic bubble lipopolyplexes did not show any severe hepatic toxicity and did not enhance the production of proinflammatory cytokines. Overall, we have succeeded in preparing anionic bubble lipopolyplexes for efficient and safe transfection with US exposure in mice

Kunitz Soybean Trypsin Inhibitor is Modified at its C-terminus by Novel Soybean Thiol Protease (Protease T1)

Kunitz soybean trypsin inhibitor (KSTI) is hydrolyzed during seed germination to yield amino acids needed to support initial seedling growth. The type of KSTI from Glycine max (L.) Merrill cv. Toyokomachi is KSTI-Ti b. The KSTI-Ti b from 4-day-old post-germination cotyledons (KSTI-Ti b’) has 3 or 4 amino acid residues cleaved off at the C-terminus. This KSTI modification is important to understand the mechanism of degradation in seed reserve proteins by proteases. Protease K1 also cleaves amino acid residues at the C-terminus of KSTI but it removes 5 amino acid residues. Therefore, we presumed the KSTI-Ti b’ was produced by a protease other than protease K1. In this study, the protease T1 responsible for cleavage of KSTI-Ti b at the C-terminus was purified. The enzyme was estimated to have a molecular mass of 33 kDa from its mobility on SDS-PAGE gels. The N-terminal amino acid sequence of the purified protease T1 corresponded to amino acids Phe-73 to Phe-92 of both thiol protease isoforms A and B from the soybean leaf, and shared 83% identity with the partial amino acid sequence of the membrane-associated cysteine protease from mung bean seedlings, a protease known to perform post-translational cleavage of C-terminal peptides of target proteins. Finally, this enzyme was shown to convert KSTI-Ti b to KSTI-Ti b’

Quantitative analysis of condensation/decondensation status of pDNA in the nuclear sub-domains by QD-FRET

Recent studies indicate that controlling the nuclear decondensation and intra-nuclear localization of plasmid DNA (pDNA) would result in an increased transfection efficiency. In the present study, we established a technology for imaging the nuclear condensation/decondensation status of pDNA in nuclear subdomains using fluorescence resonance energy transfer (FRET) between quantum dot (QD)-labeled pDNA as donor, and rhodamine-labeled polycations as acceptor. The FRET-occurring pDNA/polycation particle was encapsulated in a nuclear delivery system; a tetra-lamellar multifunctional envelope-type nano device (T-MEND), designed to overcome the endosomal membrane and nuclear membrane via step-wise fusion. Nuclear subdomains (i.e. heterochromatin and euchromatin) were distinguished by Hoechst33342 staining. Thereafter, Z-series of confocal images were captured by confocal laser scanning microscopy. pDNA in condensation/decondensation status in heterochromatin or euchromatin were quantified based on the pixel area of the signals derived from the QD and rhodamine. The results obtained indicate that modulation of the supra-molecular structure of polyrotaxane (DMAE-ss-PRX), a condenser that is cleaved in a reductive environment, conferred euchromatin-preferred decondensation. This represents the first demonstration of the successful control of condensation/decondensation in specific nuclear sub-domain via the use of an artificial DNA condenser

Impact of histamine type-2 receptor antagonists on the anticancer efficacy of gefitinib in patients with non-small cell lung cancer

Purpose Gefitinib is one of the standard treatments for non-small cell lung cancer (NSCLC) with epidermal growth factor receptor mutations. It has been reported that acid suppressants (AS) decrease the anti-tumor effect of gefitinib by reducing its solubility. AS is sometimes necessary in cancer patients; however, previous reports have not shown the most compatible AS with gefitinib administration in cancer patients. This study was conducted to determine if histamine type 2 receptor antagonists (H2RAs) can affect the anti-tumor efficacy of gefitinib. Methods Eighty-seven patients with NSCLC who were administered gefitinib were retrospectively investigated. Patients who were co-administered H2RA were compared with non-AS control patients. H2RA was administered once a day at about 3-5 or 8-12 h after gefitinib intake. The primary endpoint of this study was progression-free survival (PFS), and secondary endpoints were overall survival (OS), overall response rate (ORR), and adverse effects. Results Median PFS in H2RA group and control group was 8.0 months and 9.0 months, respectively, with no significant difference (p = 0.82). The incidence of liver dysfunction was significantly less in patients administered H2RA, whereas there were no differences between the two groups with regard to skin toxicity and diarrhea. Multivariate analysis suggested that H2RA co-administration is not a risk factor for worse PFS and OS (hazard ratio of 0.95, 0.86; 95% confidence interval of 0.60-1.48, 0.52-1.43;p = 0.82 and 0.60, respectively). Conclusion This study demonstrated that concomitant administration of H2RA with gefitinib does not affect the efficacy of gefitinib