Purpose: The insulin-like growth factor (IGF) signaling pathway is implicated in cellular mitogenesis, angiogenesis, tumor cell survival, and tumorigenesis. Inhibition of this pathway results in decreased cell growth, inhibition of tumor formation in animal models, and increased apoptosis in cells treated with cytotoxic chemotherapy. We generated and characterized a human monoclonal antibody that targeted the IGF receptor.Experimental Design: By use of XenoMouse technology, we generated CP-751,871, a fully human IgG2 antibody with high affinity (K d = 1.5 nmol/L) for human IGF-1R and evaluated its biological, pharmacologic, and antitumor properties.Results: This antibody blocks binding of IGF-1 to its receptor (IC 50 1.8 nmol/L), IGF-1-induced receptor autophosphorylation (IC 50 0.42 nmol/L) and induced the downregulation of IGF-1R in vitro and in tumor xenografts. The extent of IGF-1R down-regulation in vivo was proportional to CP-751,871 concentrations in the serum of tumor-bearing mice. Pharmacokinetic profiles in cynomolgus monkeys indicated a close to linear increase of exposure following i.v. dosing of antibody in the range of 3 to 100 mg/kg. CP-751,871 showed significant antitumor activity both as a single agent and in combination with Adriamycin, 5-fluorouracil, or tamoxifen in multiple tumor models. A biomarker assay was developed to establish the relationship between circulating antibody concentrations and down-regulation of IGF-1R in peripheral blood cells. The concentration of CP-751,871 required to down-regulate 50% of IGF-1R on peripheral blood cells was 0.3 nmol/L. Conclusion:These data suggest that inhibition of the IGF cascade by use of this monoclonal antibody may be of clinical benefit in the treatment of human cancers.

1 Pentamidine, an antiprotozoal agent, has been traditionally known to cause QT prolongation and arrhythmias; however, its ionic mechanism has not been illustrated. 2 In a stable HEK-293 cell line, we observed a concentration-dependent inhibition of the hERG current with an IC 50 of 252 mM. 3 In freshly isolated guinea-pig ventricular myocytes, pentamidine showed no effect on the L-type calcium current at concentrations up to 300 mM, with a slight prolongation of the action potential duration at this concentration. 4 Since the effective concentrations of pentamidine on the hERG channel and APD were much higher than clinically relevant exposures (B1 mM free or lower), we speculated that this drug might not prolong the QT interval through direct inhibition of I Kr channel. We therefore incubated hERG-HEK cells in 1 and 10 mM pentamidine-containing media (supplemented with 10% serum) for 48 h, and examined the hERG current densities in the vehicle control and pentamidine-treated cells. 5 In all, 36 and 85% reductions of the current densities were caused by 1-and 10-mM pentamidine treatment (Po0.001 vs control), respectively. A similar level of reduction of the hERG polypeptides and a reduced intensity of the hERG protein on the surface membrane in treated cells were observed by Western blot analysis and laser-scanning confocal microscopy, respectively. 6 Taken together, our data imply that chronic administration of pentamidine at clinically relevant exposure reduces the membrane expression of the hERG channel, which may most likely be the major mechanism of QT prolongation and torsade de pointes reported in man.

Stimulation of sensory nerves can lead to release of peptides such as substance P (SP) and consequently to neurogenic inflammation. We studied the role of bacterial lipopolysaccharide (LPS) in regulating SP-induced inflammation. Experimental cystitis was induced in female mice by intravesical instillation of SP, LPS, or fluorescein-labeled LPS. Uptake of fluorescein-labeled LPS was determined by confocal analysis, and bladder inflammation was determined by morphological analysis. SP was infused into the bladders of some mice 24 h after exposure to LPS. In vitro studies determined the capacity of LPS and SP to induce histamine and cytokine release by the bladder. LPS was taken up by urothelial cells and distributed systemically. Twenty-four hours after instillation of LPS or SP, bladder inflammation was characterized by edema and leukocytic infiltration of the bladder wall. LPS pretreatment enhanced neutrophil infiltration induced by SP, increased in vitro release of histamine, tumor necrosis factor-α, and interferon-γ, and significantly reduced transforming growth factor-β1 release. These findings suggest that LPS amplifies neurogenic inflammation, thereby playing a role in the pathogenesis of neurogenic cystitis.

Posttranslational modification by ubiquitination marks defective or outlived intracellular proteins for proteolytic degradation by the 26S proteasome. The ATP-dependent, covalent ligation and formation of polyubiquitin chains on substrate proteins requires the presence and activity of a set of ubiquitin activating and conjugating enzymes. While protein ubiquitination typically occurs in the cell cytosol or nucleus, defective mammalian spermatozoa become ubiquitinated on their surface during post-testicular sperm maturation in the epididymis, suggesting an active molecular mechanism for sperm quality control. Consequently, we hypothesized that the bioactive constituents of ubiquitin-proteasome pathway were secreted in the mammalian epididymal fluid (EF) and capable of ubiquitinating extrinsic substrates. Western blotting indeed detected the presence of the ubiquitin-activating enzyme E1 and presumed E1-ubiquitin thiol-ester intermediates, ubiquitin-carrier enzyme E2 and presumed E2-ubiquitin thiol-ester intermediates and the ubiquitin C-terminal hydrolase PGP 9.5/UCHL1 in the isolated bovine EF. Thiol-ester assays utilizing recombinant ubiquitin-activating and ubiquitin-conjugating enzymes, biotinylated substrates, and isolated bovine EF confirmed the activity of the ubiquitin activating and conjugating enzymes within EF. Ubiquitinated proteins were found to be enriched in the defective bull sperm fraction and appropriate proteasomal deubiquitinating and proteolytic activities were measured in the isolated EF by specific fluorescent substrates. The apocrine secretion of cytosolic proteins was visualized in transgenic mice and rats expressing the enhanced green fluorescent protein (eGFP) under the direction of ubiquitin-C promoter. Accumulation of eGFP, ubiquitin and proteasomes was detected in the apical blebs, the apocrine secretion sites of the caput epididymal epithelia of both the rat and mouse epididymal epithelium, although region-specific differences exist. Secretion of eGFP and proteasomes continued during the prolonged culture of the isolated rat epididymal epithelial cells in vitro. This study provides evidence that the activity of the ubiquitin system is not limited to the intracellular environment, contributing to a greater understanding of the sperm maturation process during epididymal passage.

The disassembly and reorganization of sperm-derived structures are landmarks for the onset of embryonic development. Since complete information on these events is not yet available, we examined the disassembly of the sperm axoneme, the formation of the sperm aster, and the decondensation and development of the male and female pronuclei in inseminated Rhesus monkey oocytes conceived by in-vitro fertilization (IVF) or by intracytoplasmic sperm injection. During IVF, the spermatozoa lose their acrosomes after contacting the zona pellucida, and the plasma membrane and nuclear envelope disappear after fusion with the oolemma. Subsequently, a sperm aster of microtubules forms around the proximal centriole, which is bound to the sperm connecting piece. This process is then followed by the formation of both pronuclei, which single sperm centriole later duplicates and the bipolar mitotic apparatus is observed. Following sperm injection, the spermatozoa have both an intact plasma membrane and acrosome. Although the microtubules form the sperm aster in a fashion identical to that seen during IVF, the presence of an intact acrosome appears to be associated with a heterogeneity in the decondensation of sperm chromatin. While this may indicate an abnormal pattern of chromatin decondensation during the formation of the male pronucleus following sperm injection, the male pronucleus eventually fully decondenses, as during IVF. Sperm mitochondria are displaced as the sperm centriole is exposed. Annulate lamellae and a previously undescribed organelle which seems to contain annulate lamellae precursors, as well as maternal mitochondria, are found in association with the developing pronuclear envelopes. This information increases understanding of fertilization in primates, and may also be of significance for use in assisted human reproduction as well as in the preservation of endangered mammalian species. In addition, these results demonstrates the similarities between fertilization in Rhesus monkeys and humans, providing additional evidence for the use of this non-human primate as a model system in which to investigate the cellular and molecular biological basis of human reproduction.

Interstitial cystitis (IC) is a chronic and painful bladder syndrome of unknown cause with no reliable biological marker or effective therapy. Vascular endothelial growth factor (VEGF), which plays a key role in bladder inflammation, is closely associated with the vascular alterations observed in patients with IC. However, our recent findings of VEGF receptors (VEGF-Rs) and VEGF coreceptors on nonendothelial cells in human and mouse urothelium suggest that additional VEGF targets and functions are possible in IC bladders. We report here that VEGF-Rs and coreceptors (neuropilins; NRP) are strongly expressed in both the human bladder urothelium and in the human bladder cancer cell line (J82) and that the expression of NRP2 and VEGF-R1 is significantly downregulated in IC compared with control subjects. In addition, treatment of J82 cells with bacillus Calmette-Guérin (BCG), a novel treatment strategy for IC, upregulates the messages for NRPs and VEGF-Rs. Furthermore, intravesical instillation of an internalizable VEGF fluorescent tracer (scVEGF/Cy5.5) into mouse urinary bladders results in a marked ligand accumulation in the urothelium and bladder parenchyma, indicating that urothelial VEGF-Rs are functionally active and capable of ligand interaction and internalization. Our results suggest that the VEGF pathway is altered in IC, that urinary VEGF may gain access to the bladder wall via these receptors, and that BCG treatment may replenish the missing VEGF-Rs/NRP receptors. Together, these results suggest that levels of NRPs, VEGF-Rs, and VEGF are new putative markers for the diagnosis of IC and that modulating these receptors can be exploited as therapeutic strategies.

Intracytoplasmic sperm injection (ICSI) was performed on rhesus monkey oocytes, and the resultant microtubule and DNA configurations were imaged by laser-scanning confocal microscopy. In addition, polyspermic oocytes fertilized by ICSI were examined by transmission electron microscopy (TEM). Successful rhesus fertilization by ICSI revealed microtubule and DNA configurations similar to those observed during in vitro fertilization of human and rhesus monkey oocytes, including sperm aster formation, pronuclei decondensation, spindle formation, and cell division. Several abnormalities, however, were also observed: 1) inability to complete meiosis; 2) inability to undergo male or female pronucleus formation; 3) separation of the sperm tail from the sperm nucleus; 4) premature chromosome condensation with the formation of a paternal meiotic spindle; and 5) formation of multiple female pronuclei (karyomeres) during chromosome decondensation. TEM analysis revealed that sperm can undergo decondensation in the presence of an intact acrosome at least 18 h after sperm injection. These results demonstrate the utility of rhesus ICSI in pre-clinical applications as well as with endangered species. However, the different types of fertilization failures observed here indicate that although ICSI may be a readily accepted means of fertilization of human oocytes in many clinics, we should further characterize the cellular and genetic abnormalities associated with ICSI in both human and nonhuman primates.

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