Activation of surrogate death receptor signaling triggers peroxynitrite-dependent execution of cisplatin-resistant cancer cells.

Platinum-based drugs remain as the cornerstone of cancer chemotherapy; however, development of multidrug resistance presents a therapeutic challenge. This study aims at understanding the molecular mechanisms underlying resistance to cisplatin and unraveling surrogate signaling networks that could revert sensitivity to apoptosis stimuli. We made use of three different sets of cell lines, A549 and H2030 non-small-cell lung cancer (NSCLC) and A2780 ovarian cancer cells and their cisplatin-resistant variants. Here we report that cisplatin-resistant cell lines displayed a multidrug-resistant phenotype. Changes in mitochondrial metabolism and defective mitochondrial signaling were unraveled in the resistant cells. More interestingly, a marked increase in sensitivity of the resistant cells to death receptor-induced apoptosis, in particular TRAIL (TNF-related apoptosis-inducing ligand)-mediated execution, was observed. Although this was not associated with an increase in gene transcription, a significant increase in the localization of TRAIL death receptor, DR4, to the lipid raft subdomains of plasma membrane was detected in the resistant variants. Furthermore, exposure of cisplatin-resistant cells to TRAIL resulted in upregulation of inducible nitric oxide synthase (iNOS) and increase in nitric oxide (NO) production that triggered the generation of peroxynitrite (ONOO(-)). Scavenging ONOO(-) rescued cells from TRAIL-induced apoptosis, thereby suggesting a critical role of ONOO(-) in TRAIL-induced execution of cisplatin-resistant cells. Notably, preincubation of cells with TRAIL restored sensitivity of resistant cells to cisplatin. These data provide compelling evidence for employing strategies to trigger death receptor signaling as a second-line treatment for cisplatin-resistant cancers.

Characterisation of micro-sized and nano-sized tungsten oxide-epoxy composites for radiation shielding of diagnostic X-rays.

Characteristics of X-ray transmissions were investigated for epoxy composites filled with 2-10 vol% WO3 loadings using synchrotron X-ray absorption spectroscopy (XAS) at 10-40 keV. The results obtained were used to determine the equivalent X-ray energies for the operating X-ray tube voltages of mammography and radiology machines. The results confirmed the superior attenuation ability of nano-sized WO3-epoxy composites in the energy range of 10-25 keV when compared to their micro-sized counterparts. However, at higher synchrotron radiation energies (i.e., 30-40 keV), the X-ray transmission characteristics were similar with no apparent size effect for both nano-sized and micro-sized WO3-epoxy composites. The equivalent X-ray energies for the operating X-ray tube voltages of the mammography unit (25-49 kV) were in the range of 15-25 keV. Similarly, for a radiology unit operating at 40-60 kV, the equivalent energy range was 25-40 keV, and for operating voltages greater than 60 kV (i.e., 70-100 kV), the equivalent energy was in excess of 40 keV. The mechanical properties of epoxy composites increased initially with an increase in the filler loading but a further increase in the WO3 loading resulted in deterioration of flexural strength, modulus and hardness.

Effect of particle size, filler loadings and x-ray tube voltage on the transmitted x-ray transmission in tungsten oxide-epoxy composites.

The effect of particle size, filler loadings and x-ray tube voltage on the x-ray transmission in WO(3)-epoxy composites has been investigated using the mammography unit and a general radiography unit. Results indicate that nano-sized WO(3) has a better ability to attenuate the x-ray beam generated by lower tube voltages (25-35 kV) when compared to micro-sized WO(3) of the same filler loading. However, the effect of particle size on x-ray transmission was negligible at the higher x-ray tube voltages (40-120 kV).

Modulation of Wnt/ß-catenin signaling and proliferation by a ferrous iron chelator with therapeutic efficacy in genetically engineered mouse models of cancer.

Using a screen for Wnt/ß-catenin inhibitors, a family of 8-hydroxyquinolone derivatives with in vivo anti-cancer properties was identified. Analysis of microarray data for the lead compound N-((8-hydroxy-7-quinolinyl) (4-methylphenyl)methyl)benzamide (HQBA) using the Connectivity Map database suggested that it is an iron chelator that mimics the hypoxic response. HQBA chelates Fe(2+) with a dissociation constant of ∼10(-19) M, with much weaker binding to Fe(3+) and other transition metals. HQBA inhibited proliferation of multiple cell lines in culture, and blocked the progression of established spontaneous cancers in two distinct genetically engineered mouse models of mammary cancer, MMTV-Wnt1 and MMTV-PyMT mice, without overt toxicity. HQBA may inhibit an iron-dependent factor that regulates cell-type-specific ß-catenin-driven transcription. It inhibits cancer cell proliferation independently of its effect on ß-catenin signaling, as it works equally well in MMTV-PyMT tumors and diverse ß-catenin-independent cell lines. HQBA is a promising specific intracellular Fe(2+) chelator with activity against spontaneous mouse mammary cancers.

Retrospective review of prognostic factors, including 1p19q deletion, in low-grade oligodendrogliomas and a review of recent published works.

The purpose of the present study was to investigate potential prognostic factors in low-grade oligodendrogliomas (LGOs), particularly 1p19q deletion, due to its proven prognostic significance in anaplastic oligodendrogliomas. We carried out a retrospective review of patients with a histological diagnosis of LGO between 1990 and 2000 in Auckland and Wellington, New Zealand. All cases underwent central histopathological review and FISH testing for 1p19q status. Univariate analysis of potential prognostic factors including 1p19q status, age, tumour size, tumour crossing midline, tumour enhancement, extent of surgery and seizures at diagnosis was carried out. Thirty-one patients were eligible and FISH testing was successful in 28 specimens (90%). Twenty-three specimens (82%) had 1p19q deletion; four (14%) had no 1p19q deletion; and one (4%) had 1p deletion alone. At a median follow-up of 87 months (0-147 months), median survival had not been reached and no significant difference in overall survival (OS) based on 1p19q status was detected (1p19q deletion OS 56%; 1p19q intact OS 0%; 1p deletion alone 100% (P = 0.38)). None of the other prognostic factors investigated reached statistical significance. We confirmed the high incidence (82%) of combined 1p19q deletion in LGOs and the feasibility of successful FISH testing in paraffin embedded specimens up to 10-years-old. Analysis of potential prognostic factors was limited by the lack of events during the follow-up period.

Epithelioid trophoblastic tumor: a case report.

Epithelioid trophoblastic tumor is a rare and distinctive pathologic entity within the complex family of gestational trophoblastic disease. We describe a case of epithelioid trophoblastic tumor occurring in a 34-year-old woman, who presented with a large uterine tumor 3 years following an uncomplicated pregnancy. The clinicopathologic findings in this case are typical of this unusual entity and consistent with current literature, with the exception of negative beta-human chorionic gonadotrophin levels. The distinguishing features from other intermediate trophoblastic tumors and tumor-like lesions are discussed.

Absence and labour turnover in a foundry attributable to respiratory disease.

A survey of foundry workers was undertaken to assess the effect of respiratory disease on both absence in the year prior to the survey and labour turnover since a cross-sectional study of respiratory morbidity five years previously. The presence of a wheeze, but not an objective disturbance of airway function, was predictive of absence. Those with respiratory illness, detected in the survey five years previously, were no more likely to have left the foundry than those without such illness. Limited job opportunities may discourage moulders with respiratory disease from leaving the foundry. Absence was not related to cigarette smoking, the presence of bronchial hyperreactivity, or a positive skin test to common allergens. In view of the small number of subjects in this study, studies of larger work populations should be undertaken to further assess the effect of subjective and objective indices of respiratory morbidity on absence and labour turnover.

Synthesis of shock proteins in cultured fetal mouse myocardial cells.

We examined the synthesis of shock proteins in cultured fetal mouse myocytes. The preparation is free from fibroblasts, and the cells are vital and morphologically intact with respect to beat frequency and electron microscopy. Cultured myocytes from fetal mouse heart respond to heat shock and cadmium chloride, H2O2, allylamine, cyclosporine, and azathioprine exposure with the synthesis of shock proteins. Heat shock induces the de novo synthesis of two proteins of 71 and 68 kDa; cadmium chloride induces, in addition, a protein of 30 kDa. The other substances tested provoke the synthesis only of the 30-kDa polypeptide. The formation of heat shock proteins is concentration-dependent: Cyclosporine provokes the de novo synthesis of the 30-kDa polypeptide at concentrations above 10 ng/ml, whereas azathioprine causes the same effect at concentrations above 50 micrograms/ml. Hence cyclosporine might be cardiotoxic already at concentrations below the pharmacological dosages while azathioprine influences the myocytes only at concentrations much higher than the therapeutic level. Our results indicate that heat shock protein expression in cultured myocytes may be a useful tool to monitor cardiotoxicity.

Progressive renal failure in a patient after one and two-thirds nephrectomy.

We report on a patient who lost one and two-thirds of his kidneys following surgery because of bilateral renal cell carcinoma. The serum creatinine following surgical intervention increased to about 7 mg% and fell to serum values of about 3 mg% in the year after one and two-thirds nephrectomy. The patient's renal function remained stable for 18 months, then it started to deteriorate and the patient developed progressive renal failure with proteinuria. The course of the disease suggests that an intrinsic renal mechanism was operative, which relates to glomerular hyperfiltration following surgical loss of renal tissue.

Gas chromatographic/mass spectrometric determination of carbon isotope composition in unpurified samples: methamphetamine example.

A gas chromatograph/quadrupole mass spectrometer system, operated in electron impact/selected ion monitoring mode, is used to determine the intensity ratio of the m/z 59 and the m/z 58 ions of the [C3H8N]+ fragment derived from methamphetamine samples synthesized with varying amounts of 13C-labeled methylamine. Crude products are introduced into the gas chromatograph without prior cleanup. The ratios measured were in excellent agreement with those calculated. A change in 0.25% use of 13C-methylamine is sufficient for product differentiation. The feasibility of using isotope labeling and subsequent mass spectrometric isotope ratio measurement as the basis of a compound tracing mechanism is discussed. Specifically, if methamphetamine samples manufactured from legal sources are asked to incorporate distinct 13C compositions, their sources can be traced when samples are diverted into illegal channels. Samples derived from illicit preparations can also be traced if the manufacturers of a precursor (methylamine in this case) incorporate distinct 13C compositions in their products.

Dual effect of Ca2+ on ultrasonic ATPase activity and polymerization of muscle actin.

Millimolar concentrations of Ca2+ stimulate actin polymerization whereas micromolar concentrations of Ca2+ depress polymerization. This latter effect leads to a reduction of ATPase (ATP phosphohydrolase, EC 3.6.1.3) activity of actin during sonication at low Mg2+ concentrations and in the absence of KCl. In the presence of KCl (90 mM) there is activation of ATPase activity by micromolar Ca2+ concentrations. These Ca2+ effects are half-maximal at a Ca2+ concentration of 2-10(-7) M. They can be explained by assuming that that ATPase activity is optimal in a medium range of actin polymer stability and that micromolar Ca2+ concentrations tend to labilize and depolymerize F-actin.

Effect of cytochalasin B on formation and properties of muscle F-actin.

Cytochalasin B stimulated polymerization and decreased the concentration of G-actin remaining in equilibrium with F-actin filaments. Polymerization in the presence of cytochalasin B gave rise to a smaller increase of viscosity but to the same increase in light scattering, compared to polymerization in the absence of cytochalasin B. Cytochalasin B reduced the viscosity of F-actin and caused the appearance of ATP hydrolysis by F-actin. The cytochalasin B-induced ATPase activity was inhibited by concentrations of KCl higher than 50 mM. The cytochalasin B-induced ATPase activity was enhanced by ethyleneglycol bis(alpha-aminoethyl ether)-N,N'-tetraacetic acid and reduced by MgCl2 at concentrations higher than 0.75 mM. The findings suggest that the stability of actin filaments is reduced by cytochalasin B.

Interaction of actin with phalloidin: polymerization and stabilization of F-actin.

The cyclic peptide phalloidin, one of the toxic components of Amanita phalloides prevented the drop of viscosity of F-actin solutions after the addition of 0.6 M KI and inhibited the ATP splitting of F-actin during sonic vibration. The data concerning ATP splitting are consistent with the assumption (a) that only 1 out of every 3 actin units of the filaments needs to be combined with phalloidin in order to suppress the contribution of these 3 actins to the ATPase activity of the filament and (b) that all actin units of the filaments can combine with phalloidin with a very high affinity. -halloidin did not only stabilize the actin-actin bonds in the F-actin structure but it also increased the rate of polymerization of G-actin to F-actin. The ability of F-actin to activate myosin ATPase was not affected by phalloidin. The tropomyosin-troponin complex did not prevent the stabilizing effect of phalloidin on the F-actin structure.