Unleashing the full potential of Hsp90 inhibitors as cancer therapeutics through simultaneous inactivation of Hsp90, Grp94, and TRAP1

Cancer therapeutics: Extending a drug's reach A new drug that blocks heat shock proteins (HSPs), helper proteins that are co-opted by cancer cells to promote tumor growth, shows promise for cancer treatment. Several drugs have targeted HSPs, since cancer cells are known to hijack these helper proteins to shield themselves from destruction by the body. However, the drugs have had limited success. Hye-Kyung Park and Byoung Heon Kang at Ulsan National Institutes of Science and Technology in South Korea and coworkers noticed that the drugs were not absorbed into mitochondria, a key cellular compartment, and HSPs in this compartment were therefore not being blocked. They identified a new HSP inhibitor that can reach every cellular compartment and inhibit all HSPs. Testing in mice showed that this inhibitor effectively triggered death of tumor cells, and therefore shows promise for anti-cancer therapy. The Hsp90 family proteins Hsp90, Grp94, and TRAP1 are present in the cell cytoplasm, endoplasmic reticulum, and mitochondria, respectively; all play important roles in tumorigenesis by regulating protein homeostasis in response to stress. Thus, simultaneous inhibition of all Hsp90 paralogs is a reasonable strategy for cancer therapy. However, since the existing pan-Hsp90 inhibitor does not accumulate in mitochondria, the potential anticancer activity of pan-Hsp90 inhibition has not yet been fully examined in vivo. Analysis of The Cancer Genome Atlas database revealed that all Hsp90 paralogs were upregulated in prostate cancer. Inactivation of all Hsp90 paralogs induced mitochondrial dysfunction, increased cytosolic calcium, and activated calcineurin. Active calcineurin blocked prosurvival heat shock responses upon Hsp90 inhibition by preventing nuclear translocation of HSF1. The purine scaffold derivative DN401 inhibited all Hsp90 paralogs simultaneously and showed stronger anticancer activity than other Hsp90 inhibitors. Pan-Hsp90 inhibition increased cytotoxicity and suppressed mechanisms that protect cancer cells, suggesting that it is a feasible strategy for the development of potent anticancer drugs. The mitochondria-permeable drug DN401 is a newly identified in vivo pan-Hsp90 inhibitor with potent anticancer activity

ATPase mechanism of the 5'-3' DNA helicase, RecD2: evidence for a pre-hydrolysis conformation change

The superfamily 1 helicase, RecD2, is a monomeric, bacterial enzyme with a role in DNA repair, but with 5'-3' activity unlike most enzymes from this superfamily. Rate constants were determined for steps within the ATPase cycle of RecD2 in the presence of ssDNA. The fluorescent ATP analog, mantATP (2'(3')-O-(N-methylanthraniloyl)ATP), was used throughout to provide a complete set of rate constants and determine the mechanism of the cycle for a single nucleotide species. Fluorescence stopped-flow measurements were used to determine rate constants for adenosine nucleotide binding and release, quenched-flow measurements were used for the hydrolytic cleavage step, and the fluorescent phosphate biosensor was used for phosphate release kinetics. Some rate constants could also be measured using the natural substrate, ATP, and these suggested a similar mechanism to that obtained with mantATP. The data show that a rearrangement linked to Mg(2+) coordination, which occurs before the hydrolysis step, is rate-limiting in the cycle and that this step is greatly accelerated by bound DNA. This is also shown here for the PcrA 3'-5' helicase and so may be a general mechanism governing superfamily 1 helicases. The mechanism accounts for the tight coupling between translocation and ATPase activity

Cortical synaptogenesis and excitatory synapse number are determined via a Neuroligin-1-dependent intercellular competition

Members of the neuroligin (NL) family of cell-adhesion proteins are found at excitatory and inhibitory synapses and are mutated in some familial forms of autism spectrum disorders. Although they display synaptogenic properties in heterologous systems, a function of NLs in vivo in regulating synapse formation and synapse number has been difficult to establish. Here we show that neuroligin-1 (NL1), which is located at excitatory post-synaptic densities, does regulate activity-dependent synaptogenesis as well as mature synapse number on cortical layer 2/3 pyramidal neurons in vivo. However, synapse number is not sensitive to absolute NL1 levels but rather to transcellular differences in the relative amounts of NL1. These effects are independent of the cell-autonomous regulation of NMDA-type glutamate receptors by absolute levels of NL1. Our data indicate that transcellular competitive processes govern synapse formation and number in developing cortex and that NL1 plays a central function in these processes

Voiding Dysfunction after Total Mesorectal Excision in Rectal Cancer

Purpose The aim of this study was to assess the voiding dysfunction after rectal cancer surgery with total mesorectal excision (TME). Methods This was part of a prospective study done in the rectal cancer patients who underwent surgery with TME between November 2006 and June 2008. Consecutive uroflowmetry, post-voided residual volume, and a voiding questionnaire were performed at preoperatively and postoperatively. Results A total of 50 patients were recruited in this study, including 28 male and 22 female. In the comparison of the preoperative data with the postoperative 3-month data, a significant decrease in mean maximal flow rate, voided volume, and post-voided residual volume were found. In the comparison with the postoperative 6-month data, however only the maximal flow rate was decreased with statistical significance (P=0.02). In the comparison between surgical methods, abdominoperineal resection patients showed delayed recovery of maximal flow rate, voided volume, and post-voided residual volume. There was no significant difference in uroflowmetry parameters with advances in rectal cancer stage. Conclusions Voiding dysfunction is common after rectal cancer surgery but can be recovered in 6 months after surgery or earlier. Abdominoperineal resection was shown to be an unfavorable factor for postoperative voiding. Larger prospective study is needed to determine the long-term effect of rectal cancer surgery in relation to male and female baseline voiding condition

ATIC and PAMELA Results on Cosmic e^\pm Excesses and Neutrino Masses

Recently the ATIC and PAMELA collaborations released their results which show the abundant e^\pm excess in cosmic rays well above the background, but not for the \bar{p}. Their data if interpreted as the dark matter particles' annihilation imply that the new physics with the dark matter is closely related to the lepton sector. In this paper we study the possible connection of the new physics responsible for the cosmic e^\pm excesses to the neutrino mass generation. We consider a class of models and do the detailed numerical calculations. We find that these models can natually account for the ATIC and PAMELA e^\pm and \bar{p} data and at the same time generate the small neutrino masses.Comment: 7 pages, 5 figures. Published version with minor corrections and more reference

TRAIL sensitize MDR cells to MDR-related drugs by down-regulation of P-glycoprotein through inhibition of DNA-PKcs/Akt/GSK-3β pathway and activation of caspases

<p>Abstract</p> <p>Background</p> <p>The development of new modulator possessing high efficacy, low toxicity and high selectivity is a pivotal approach to overcome P-glycoprotein (P-gp) mediated multidrug resistance (MDR) in cancer treatment. In this study, we suggest a new molecular mechanism that TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) down-regulates P-glycoprotein (P-gp) through inhibition of DNA-PKcs/Akt/GSK-3β pathway and activation of caspases and thereby sensitize MDR cells to MDR-related drugs.</p> <p>Results</p> <p>MDR variants, CEM/VLB_10-2, CEM/VLB_55-8and CEM/VLB₁₀₀cells, with gradually increased levels of P-gp derived from human lymphoblastic leukemia CEM cells, were gradually more susceptible to TRAIL-induced apoptosis and cytotoxicity than parental CEM cells. The P-gp level of MDR variants was positively correlated with the levels of DNA-PKcs, pAkt, pGSK-3β and c-Myc as well as DR5 and negatively correlated with the level of c-FLIPs. Hypersensitivity of CEM/VLB₁₀₀cells to TRAIL was accompanied by the activation of mitochondrial apoptotic pathway as well as the activation of initiator caspases. In addition, TRAIL-induced down-regulation of DNA-PKcs/Akt/GSK-3β pathway and c-FLIP and up-regulation of cell surface expression of death receptors were associated with the increased susceptibility to TRAIL of MDR cells. Moreover, TRAIL inhibited P-gp efflux function via caspase-3-dependent degradation of P-gp as well as DNA-PKcs and subsequently sensitized MDR cells to MDR-related drugs such as vinblastine and doxorubicin. We also found that suppression of DNA-PKcs by siRNA enhanced the susceptibility of MDR cells to vincristine as well as TRAIL via down-regulation of c-FLIP and P-gp expression and up-regulation of DR5.</p> <p>Conclusion</p> <p>This study showed for the first time that the MDR variant of CEM cells was hypersensitive to TRAIL due to up-regulation of DR5 and concomitant down-regulation of c-FLIP, and degradation of P-gp and DNA-PKcs by activation of caspase-3 might be important determinants of TRAIL-induced sensitization of MDR cells to MDR-related drugs. Therefore, combination of TRAIL and chemotherapeutic drugs may be a good strategy for treatment of cancer with multidrug resistance.</p

Eikenella Corrodens Cervical Spinal Epidural Abscess Induced by a Fish Bone

Cervical spinal epidural abscess, caused by fish bone injury and a secondary infection by Eikenella Corrodens which is part of the normal flora, has not been reported. A 72-yr-old man came to the hospital with pain in his posterior neck and both shoulders for 2 months. He also was experiencing weakness on his right side for 3 days. A fish bone had been stuck in his throat for about 2 months. Neurological examination revealed right hemiparesis, hypesthesia on the left extremities and neck stiffness. Laboratory findings showed an elevated ESR/CRP and leukocytosis, and magnetic resonance imaging revealed a retropharyngeal abscess and cervical myelitis. The patient was treated with emergency surgical decompression and antibiotics. A fish bone was removed from the C3-C4 intervertebral disc space. In the culture of chocolate blood agar and 5% sheep blood agar plate, E. corrodens was detected as a causative organism