Antitumor agents. 258. Syntheses and evaluation of dietary antioxidant--taxoid conjugates as novel cytotoxic agents

Various dietary antioxidants, including vitamins, flavonoids, curcumin, and a coumarin, were conjugated with paclitaxel (1) through an ester linkage. The newly synthesized compounds were evaluated for cytotoxic activity against several human tumor cell lines as well as the corresponding normal cell lines. Interestingly, most tested conjugates selectively inhibited the growth of 1A9 (ovarian) and KB (nasopharyngeal) tumor cells without activity against other cell lines. Particularly, conjugates 16 and 20 were highly active against 1A9 (ED(50) value of 0.005 microg/mL) as well as KB (ED(50) values of 0.005 and 0.14 microg/mL, respectively) cells. Compound 22b, the glycinate ester salt of vitamin E conjugated with 1, appears to be a promising lead for further development as a clinical trial candidate as it exhibited strong inhibitory activity against Panc-1 (pancreatic cancer) with less effect on the related E6E7 (normal) cell line.     

A phospho-proteomic screen identifies novel S6K1 and mTORC1 substrates revealing additional complexity in the signaling network regulating cell growth

S6K1, a critical downstream substrate of mTORC1, has been implicated in regulating protein synthesis and a variety of processes that impinge upon cell growth and proliferation. While the role of the cytoplasmic p70^S6K1 isoform in the regulation of translation has been intensively studied, the targets and function of the nuclear p85^S6K1 isoform remain unclear. Therefore, we carried out a phospho-proteomic screen to identify novel p85^S6K1 substrates. Four novel putative p85^S6K1 substrates, GRP75, CCTβ, PGK1 and RACK1, and two mTORC1 substrates, ANXA4 and PSMA6 were identified, with diverse roles in chaperone function, ribosome maturation, metabolism, vesicle trafficking and the proteasome, respectively. The chaperonin subunit CCTβ was further investigated and the site of phosphorylation mapped to serine 260, a site located in the chaperonin apical domain. Consistent with this domain being involved in folding substrate interactions, we found that phosphorylation of serine 260 modulates chaperonin folding activity.     

在昆虫细胞中高效表达蓝舌病毒VP7蛋白作为组特异性诊断抗原

对蓝舌病毒结构蛋白ＶＰ７作为组特异性诊断抗原进行了研究,将编码ＢＴＶ１３主要组特异性抗原ＶＰ７的Ｓ７ｃＤＮＡ插入杆状病毒表达载体ｐＦａｓｔＢａｃ１,通过同源重组获得了重组杆状病毒ｅｖＢａｃＢＴＶＰ７。用此重组病毒感染昆虫细胞获得ＶＰ７蛋白的高效表达,表达量可占细胞蛋白总量的１２．４％。     

Proliferation of myofibroblasts in the stroma of renal oncocytoma

Objectives: Myofibroblasts are a vital component of stroma of many malignant neoplasms, but it is not yet established whether stromal myofibroblasts also exist in benign tumours such as oncocytoma of the kidney. Materials and methods: Histomorphological and immunohistochemical analysis of 16 renal oncocytomas diagnosed at Chang Gung Memorial Hospital, Taiwan, has been performed. Results: Renal oncocytomas were composed of oncocytes, large cells with granular eosinophilic cytoplasm, arranged mostly in sheets, in tubulocystic or combined pattern. Few oncocytes appeared to be undergoing proliferation or apoptosis. MIB‐1 and active caspase 3 indices were low, but higher in tumour than in surrounding non‐tumour parenchyma (MIB‐1: 0.93 ± 0.09 versus 0.46 ± 0.07, P < 0.001 and active caspase 3: 0.76 ± 0.08 versus 0.41 ± 0.09, P < 0.001). Wnt/β‐catenin signalling was not implicated in this neoplasm, as there was no loss of E‐cadherin membranous localization or expression of intranuclear β‐catenin in the cells. Clumps of oncocytes were stained with periodic acid Schiff and had collagen I‐, collagen III‐ and fibronectin‐positive, but desmin‐ and human caldesmon‐negative stromas. Importantly, α‐smooth muscle actin (SMA)‐immunostaining established the myofibroblastic nature of many of the stromal cells. Some of the myofibroblasts were also positive for MIB‐1, indicating a proliferative role for them in the stroma. Conclusions: Renal oncocytomas were composed of two independent compartments: benign oncocytes and pronounced fibrotic stroma, which consisted of proliferating myofibroblasts (SMA‐ and MIB‐1‐positive) which were associated with excessive deposition of extracellular matrix (periodic acid Schiff‐component, collagen I‐, collagen III‐ and fibronectin‐positive, and desmin‐ and human caldesmon‐negative).     

Solvent effects on the conformational transition of a model polyalanine peptide

We have investigated the folding of polyalanine by combining discontinuous molecular dynamics simulation with our newly developed off-lattice intermediate-resolution protein model. The thermodynamics of a system containing a single Ac-KA(14)K-NH(2) molecule has been explored by using the replica exchange simulation method to map out the conformational transitions as a function of temperature. We have also explored the influence of solvent type on the folding process by varying the relative strength of the side-chain's hydrophobic interactions and backbone hydrogen bonding interactions. The peptide in our simulations tends to mimic real polyalanine in that it can exist in three distinct structural states: alpha-helix, beta-structures (including beta-hairpin and beta-sheet-like structures), and random coil, depending upon the solvent conditions. At low values of the hydrophobic interaction strength between nonpolar side-chains, the polyalanine peptide undergoes a relatively sharp transition between an alpha-helical conformation at low temperatures and a random-coil conformation at high temperatures. As the hydrophobic interaction strength increases, this transition shifts to higher temperatures. Increasing the hydrophobic interaction strength even further induces a second transition to a beta-hairpin, resulting in an alpha-helical conformation at low temperatures, a beta-hairpin at intermediate temperatures, and a random coil at high temperatures. At very high values of the hydrophobic interaction strength, polyalanines become beta-hairpins and beta-sheet-like structures at low temperatures and random coils at high temperatures. This study of the folding of a single polyalanine-based peptide sets the stage for a study of polyalanine aggregation in a forthcoming paper.     

Human Spotted Fever Group Rickettsioses Are Underappreciated in Southern Taiwan,Particularly for the Species Closely-Related to Rickettsia felis

Background

Despite increased identification of spotted fever group rickettsioses (SFGR) in animals and arthropods, human SFGR are poorly characterized in Taiwan.

Methods

Patients with suspected Q fever, scrub typhus, murine typhus, leptospirosis, and dengue fever from April 2004 to December 2009 were retrospectively investigated for SFGR antibodies (Abs). Sera were screened for Rickettsia rickettsii Abs by indirect immunofluorescence antibody assay (IFA), and those with positive results were further examined for Abs against R. rickettsii, R. typhi, R. felis, R. conorii, and R. japonica using micro-immunofluorescence (MIF) tests. Polymerase chain reaction (PCR) for detection of SFGR DNA was applied in those indicated acute infections. Case geographic distribution was made by the geographic information system software.

Results

A total of 413 cases with paired serum, including 90 cases of Q fever, 47 cases of scrub typhus, 12 cases of murine typhus, 6 cases of leptospirosis, 3 cases of dengue fever, and 255 cases of unknown febrile diseases were investigated. Using IFA tests, a total of 49 cases with 47 (11.4%) and 4 (1.0%) cases had sera potentially positive for R. rickettsii IgG and IgM, respectively. In the 49 cases screened from IFA, MIF tests revealed that there were 5 cases of acute infections (3 possible R. felis and 2 undetermined SFGR) and 13 cases of past infections (3 possible R. felis and 10 undetermined SFGR). None of the 5 cases of acute infection had detectable SFGR DNA in the blood specimen by PCR. Possible acute infection of R. felis was identified in both one case of Q fever and scrub typhus. The geographic distribution of SFGR cases is similar with that of scrub typhus.

Conclusions

Human SFGR exist and are neglected diseases in southern Taiwan, particularly for the species closely-related to R. felis.     

Influenza A H5N1 clade 2.3.4 virus with a different antiviral susceptibility profile replaced clade 1 virus in humans in northern Vietnam

Background

Prior to 2007, highly pathogenic avian influenza (HPAI) H5N1 viruses isolated from poultry and humans in Vietnam were consistently reported to be clade 1 viruses, susceptible to oseltamivir but resistant to amantadine. Here we describe the re-emergence of human HPAI H5N1 virus infections in Vietnam in 2007 and the characteristics of the isolated viruses.

Methods and Findings

Respiratory specimens from patients suspected to be infected with avian influenza in 2007 were screened by influenza and H5 subtype specific polymerase chain reaction. Isolated H5N1 strains were further characterized by genome sequencing and drug susceptibility testing. Eleven poultry outbreak isolates from 2007 were included in the sequence analysis. Eight patients, all of them from northern Vietnam, were diagnosed with H5N1 in 2007 and five of them died. Phylogenetic analysis of H5N1 viruses isolated from humans and poultry in 2007 showed that clade 2.3.4 H5N1 viruses replaced clade 1 viruses in northern Vietnam. Four human H5N1 strains had eight-fold reduced in-vitro susceptibility to oseltamivir as compared to clade 1 viruses. In two poultry isolates the I117V mutation was found in the neuraminidase gene, which is associated with reduced susceptibility to oseltamivir. No mutations in the M2 gene conferring amantadine resistance were found.

Conclusion

In 2007, H5N1 clade 2.3.4 viruses replaced clade 1 viruses in northern Vietnam and were susceptible to amantadine but showed reduced susceptibility to oseltamivir. Combination antiviral therapy with oseltamivir and amantadine for human cases in Vietnam is recommended.     

Houttuynia cordata Targets the Beginning Stage of Herpes Simplex Virus Infection

Herpes simplex virus (HSV), a common latent virus in humans, causes certain severe diseases. Extensive use of acyclovir (ACV) results in the development of drug-resistant HSV strains, hence, there is an urgent need to develop new drugs to treat HSV infection. Houttuynia cordata (H. cordata), a natural herbal medicine, has been reported to exhibit anti-HSV effects which is partly NF-κB-dependent. However, the molecular mechanisms by which H. cordata inhibits HSV infection are not elucidated thoroughly. Here, we report that H. cordata water extracts (HCWEs) inhibit the infection of HSV-1, HSV-2, and acyclovir-resistant HSV-1 mainly via blocking viral binding and penetration in the beginning of infection. HCWEs also suppress HSV replication. Furthermore, HCWEs attenuate the first-wave of NF-κB activation, which is essential for viral gene expressions. Further analysis of six compounds in HCWEs revealed that quercetin and isoquercitrin inhibit NF-κB activation and additionally, quercetin also has an inhibitory effect on viral entry. These results indicate that HCWEs can inhibit HSV infection through multiple mechanisms and could be a potential lead for development of new drugs for treating HSV.     

New class of HIV-1 integrase (IN) inhibitors with a dual mode of action

tert-Butoxy-(4-phenyl-quinolin-3-yl)-acetic acids (tBPQA) are a new class of HIV-1 integrase (IN) inhibitors that are structurally distinct from IN strand transfer inhibitors but analogous to LEDGINs. LEDGINs are a class of potent antiviral compounds that interacts with the lens epithelium-derived growth factor (LEDGF) binding pocket on IN and were identified through competition binding against LEDGF. LEDGF tethers IN to the host chromatin and enables targeted integration of viral DNA. The prevailing understanding of the antiviral mechanism of LEDGINs is that they inhibit LEDGF binding to IN, which prevents targeted integration of HIV-1. We showed that in addition to the properties already known for LEDGINs, the binding of tBPQAs to the IN dimer interface inhibits IN enzymatic activity in a LEDGF-independent manner. Using the analysis of two long terminal repeat junctions in HIV-infected cells, we showed that the inhibition by tBPQAs occurs at or prior to the viral DNA 3'-processing step. Biochemical studies revealed that this inhibition operates by compound-induced conformational changes in the IN dimer that prevent proper assembly of IN onto viral DNA. For the first time, tBPQAs were demonstrated to be allosteric inhibitors of HIV-1 IN displaying a dual mode of action: inhibition of IN-viral DNA assembly and inhibition of IN-LEDGF interaction.     

The indispensable role of CCR5 for in vivo suppressor function of tumor-derived CD103+ effector/memory regulatory T cells

CD103 is a marker for identification of effector/memory regulatory T cells (Tregs). CD103(+) Tregs are potent suppressors of tissue inflammation in several infectious diseases, autoimmune diseases, and cancers. However, the underlying mechanisms for this potent suppression ability remain unclear. The current study was designed to clarify this issue. Unexpectedly, we found both CD103(+) and CD103(-) Tregs had similar suppression capacity in vitro. We then chose a murine tumor model for investigation of the in vivo behavior of these Tregs. The suppression ability in vivo against the anti-tumor ability of CD8(+) T cells was restricted to CD103(+) Tregs although both Tregs had equal in vitro suppression ability. In addition, CD103(+) Tregs expressed significantly higher levels of CCR5 than those of CD103(-) Tregs and accumulated more in tumors than did CD103(-) Tregs. Furthermore, blockade of CCR5 signaling, either by CCR5(-/-)CD103(+) Tregs or by CCL5 knockdown tumor, could reduce the migration of CD103(+) Tregs into tumors and impair their in vivo suppression ability. In conclusion, these results indicate that the potent in vivo suppression ability of CD103(+) Tregs is due to the tissue-migration ability through CCR5 expression.