Inhibition of TGF-beta with neutralizing antibodies prevents radiation-induced acceleration of metastatic cancer progression

We investigated whether TGF-beta induced by anticancer therapies accelerates tumor progression. Using the MMTV/PyVmT transgenic model of metastatic breast cancer, we show that administration of ionizing radiation or doxorubicin caused increased circulating levels of TGF-beta1 as well as increased circulating tumor cells and lung metastases. These effects were abrogated by administration of a neutralizing pan-TGF-beta antibody. Circulating polyomavirus middle T antigen-expressing tumor cells did not grow ex vivo in the presence of the TGF-beta antibody, suggesting autocrine TGF-beta is a survival signal in these cells. Radiation failed to enhance lung metastases in mice bearing tumors that lack the type II TGF-beta receptor, suggesting that the increase in metastases was due, at least in part, to a direct effect of TGF-beta on the cancer cells. These data implicate TGF-beta induced by anticancer therapy as a pro-metastatic signal in tumor cells and provide a rationale for the simultaneous use of these therapies in combination with TGF-beta inhibitors.     

Benzodiazepine interactions with central thyroid-releasing hormone binding sites: characterization and physiological significance

Thyrotropin-releasing hormone (TRH) and several TRH analogs were examined in the [3H]-3-Me-His2-TRH ([3H]MeTRH) receptor-binding assay in rat amygdala, striatal and cortical membranes. The benzodiazepine, chlordiazepoxide, as reported in the literature was found to displace [3H]MeTRH with an IC50 value of 3.6 X 10(-7) M in amygdala membranes. Midazolam was, however, identified as being 6-fold more active than chlordiazepoxide with an IC50 value of 6.3 X 10(-8) M. The effect of these benzodiazepines on [3H]MeTRH binding did not appear to be related to their anxiolytic activity because the novel pyrazoloquinoline nonsedating anxiolytic, CGS 9896 was without effect on [3H]MeTRH binding at concentrations up to 1 X 10(-5) M. Chlordiazepoxide had similar activity in cortical membranes whereas midazolam was some 5 times less active in this preparation than in amygdala. Both compounds were weak displacers of [3H]MeTRH binding in striatal membranes, being at least two orders of magnitude less potent than in amygdala. In contrast TRH and its analogs, RX 77368 and DN-1417, were approximately 2 to 8 times more active in striatum than amygdala membranes. TRH and DN-1417 were less active in cortical membranes whereas RX 77368 was some three times more active than in striatum and amygdala. In three test procedures indicative of TRH agonist activity; thyroid-stimulating hormone release, reversal of pentobarbital sleeping time in mice and elevation of cerebellar cyclic GMP levels, the benzodiazepines were found to be devoid of activity, whereas TRH and related compounds produced their expected responses.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of Corticosteroids on Human Monocyte Function

This report examined the effect of corticosteroids in vitro on human peripheral blood monocytes, essential cells in both immune and nonimmune cellular defense mechanisms. Monocyte chemotaxis in response to sera, Escherichia coli filtrate, and lymphokine chemotactic factor was markedly reduced (P < 0.01) by hydrocortisone succinate (HCS) at 16 mug/ml. Methylprednisolone succinate and unesterified hydrocortisone produced similar impairment of monocyte chemotaxis while two drugs which unmodified do not enter cells, hydrocortisone phosphate (HCP) and cortisone acetate, had no effect on chemotaxis. HCS also significantly impaired monocyte random migration at 16 mug/ml. Monocyte bactericidal activity was reduced by HCS at 16 mug/ml (P < 0.01)) but was not affected by HCP even at 120 mug/ml. In comparison, HCS did not alter granulocyte chemotaxis even at 500 mug/ml, and bactericidal activity was reduced at 16 mug/ml (P < 0.01). Monocyte phagocytosis of cryptococci was reduced only 20% (P < 0.05) at 120 mug/ml. HCS at 120 mug/ml did not alter monocyte base-line or postphagocytic hexosemonophosphate shunt activity, viability by trypan blue exclusion, adherence to tissue culture flasks, or surface binding of IgG globulin. These corticosteroid-induced defects in monocyte function may contribute to reduced cellular defense during corticosteroid therapy.     

The 14C, 13C,and 15N syntheses of a potent VEGFR‐2 kinase inhibitor,Brivanib, and its prodrug,Brivanib Alaninate

The interruption of tyrosine kinase vascular endothelial growth factor receptor‐2 (VEGFR‐2) signaling by the binding of a small molecule inhibitor, for example, Brivanib, to VEGFR‐2 kinase domain has been shown as an effective method of slowing angiogenesis and tumor progression. [¹⁴C]Brivanib, 13 and its prodrug [¹⁴C]Brivanib Alaninate, 15 were prepared to support preclinical and clinical studies. Their respective stable isotope‐labeled versions, [¹³CN₂]Brivanib, 21 and [¹³CN₂]Brivanib Alaninate, 28, were also prepared to support bioanalytical LC‐MS analyses of clinical samples. All of the four title compounds were synthetically derived from the respective isotopically labeled common pyrrolotriazinone intermediate, 6 or 16. This labeled central core pyrrolotriazinone was also conveniently used to synthesize other structurally related drug discovery candidates. Copyright © 2011 John wiley & Sons, Ltd.     

Acquired resistance to EGFR tyrosine kinase inhibitors in cancer cells is mediated by loss of IGF-binding proteins

Although some cancers are initially sensitive to EGFR tyrosine kinase inhibitors (TKIs), resistance invariably develops. We investigated mechanisms of acquired resistance to the EGFR TKI gefitinib by generating gefitinib-resistant (GR) A431 squamous cancer cells. In GR cells, gefitinib reduced phosphorylation of EGFR, ErbB-3, and Erk but not Akt. These cells also showed hyperphosphorylation of the IGFI receptor (IGFIR) and constitutive association of IRS-1 with PI3K. Inhibition of IGFIR signaling disrupted the association of IRS-1 with PI3K and restored the ability of gefitinib to downregulate PI3K/Akt signaling and to inhibit GR cell growth. Gene expression analyses revealed that GR cells exhibited markedly reduced IGF-binding protein 3 (IGFBP-3) and IGFBP-4 RNA. Addition of recombinant IGFBP-3 restored the ability of gefitinib to downregulate PI3K/Akt signaling and to inhibit cell growth. Finally, gefitinib treatment of mice with A431 xenografts in combination with an IGFIR-specific monoclonal antibody prevented tumor recurrence, whereas each drug given alone was unable to do so. These data suggest that loss of expression of IGFBPs in tumor cells treated with EGFR TKIs derepresses IGFIR signaling, which in turn mediates resistance to EGFR antagonists. Moreover, combined therapeutic inhibition of EGFR and IGFIR may abrogate this acquired mechanism of drug resistance and is thus worthy of prospective clinical investigation.     

The health hazards posed by chromium-contaminated soils in residential and industrial areas: conclusions of an expert panel.

Between 1905 and 1971, over 2 million tons of residue from chromite ore processing was generated in Hudson County, New Jersey, of which substantial amounts were used as fill and tank diking. A panel of medical, toxicology, and risk assessment experts was convened in early 1990 to evaluate the potential health hazards posed by the resulting chromium contaminated soil. The Panel concluded that soils containing concentrations of 75 ppm hexavalent chromium [Cr(VI)] and 1000 ppm total chromium compounds (about 95% was trivalent chromium [Cr(III)]) did not pose a significant health hazard to nearby residents and workers. They also determined that exposure to chromium from Hudson County sites posed a negligible cancer hazard to residents. Using risk assessment methods, the Panel estimated that the plausible incremental cancer risk to individuals at residential sites would be substantially less than 1 in 1,000,000. The average measured levels of airborne Cr(VI) at typical industrial sites were more than 1000-fold lower than the current OSHA Permissible Exposure Limit (PEL). The maximum plausible increased cancer risk for an average worker at a dusty industrial site was estimated to be less than 1 in 100,000. The Panel also concluded that chromium-containing crystals, which have occasionally been found in Hudson County buildings, do not pose a significant hazard. However, they suggested that were the concentration to exceed 5000 ppm Cr(VI) in the crystals, site-specific health risk assessments would be conducted and remediation considered. The Panel evaluated the dermal hazard posed by chromium-contaminated soil and acknowledged that there is a small group of persons (approximately 0.1% of the United States population) who currently have a dermal sensitization to Cr(VI) primarily through occupational exposure. Based on published studies of human volunteers, the Panel concluded that a small percentage (less than 5%) of persons already sensitized may respond to Cr(VI) in solution at concentrations above 35 ppm. They decided that a much higher concentration in soil, perhaps 350 ppm Cr(VI), would be necessary to elicit dermatitis because only a fraction of the chromium in soil is soluble. The Panel concluded that it was highly unlikely (if not impossible) for a person to become dermally sensitized to Cr(VI) or Cr(III) at the soil concentrations found in most areas in Hudson County.(ABSTRACT TRUNCATED AT 400 WORDS)     

Comparison of the hamster sperm motility assay to the mouse one-cell and two-cell embryo bioassays as quality control tests for in vitro fertilization

The hamster sperm motility assay, mouse one-cell embryo, and mouse two-cell embryo bioassays were used to test modified Tyrode's solution and modified Ham's F-10 (Gibco, Grand Island, NY) medium prepared in tap water versus ultrapure water. Factors influencing the ability of each assay to discriminate water quality were evaluated to characterize these assays for quality control use in the in vitro fertilization laboratory. The hamster sperm motility assay reproducibly detected differences in treatment without significant interanimal, interanalyst, or interassay variation. Interanalyst and interanimal variation significantly affected the ability to detect treatment differences using the mouse bioassays. Sample sizes needed to predict clinically significant treatment effects were calculated using varying assay conditions. Ham's F-10 medium can be tested with the hamster sperm motility assay.     

Two new L-serine variants of microcystins-LR and -RR from Anabaena sp. strains 202 A1 and 202 A2.

Two new microcystins, [L-Ser7]microcystin-LR (1) and [L-Ser7]microcystin-RR (2), were isolated from a filamentous fresh water cyanobacterium (blue-green alga), Anabaena sp. strain 202 A1, along with the two major toxins, [Dha7]microcystin-LR (3) and [Dha7]microcystin-RR (4) and their minor components the D-Asp variants [D-Asp3,Dha7]microcystin-LR (5) and [D-Asp3,Dha7]microcystin-RR (6). Anabaena sp. strain 202 A1 also produced another new toxin, whose structure is tentatively proposed as [D-Asp3,L-Ser7]microcystin-XR (7), where X is a leucine homologue. Anabaena sp. strain 202 A2 produced one new microcystin, 1, and three known microcystins, 3, 4, and 5. The structures of the toxins were assigned based on their amino acid analyses, and fast atom bombardment mass spectrometry data.     

Characterization and modulation of human lymphokine (interleukin 2) activated killer cell induction

Culture of human peripheral blood mononuclear cells with purified interleukin 2 (IL-2) results in the induction of a cytotoxic population of cells capable of lysing autologous tumor cells and natural killer (NK) cell resistant tumor cell lines. The current study was undertaken to characterize biological agents which might modulate the induction of lymphokine (IL-2) activated killer (LAK) cells and to optimize culture conditions for LAK cell induction. Preliminary studies were undertaken to characterize optimal time and IL-2 concentration for induction of LAK cell activity. Subsequently, we demonstrated that: (a) LAK cell induction is inhibited at high (2.5 X 10(6)/ml) cell concentrations and this phenomenon is due to the presence of monocytes; (b) depletion of monocytes allows LAK cell induction at 5-10-fold higher cell concentrations without altering the extent or range of LAK-cell activity; (c) interleukin 1 enhances and alpha- and beta-interferons inhibit IL-2 induced proliferation, without altering LAK cell induction; and (d) gamma-interferon alters neither IL-2 induction of proliferation nor LAK cell activity.