Blocking the GITR-GITRL pathway to overcome resistance to therapy in sarcomatoid malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is an aggressive neoplasm originating from the pleura. Non-epithelioid (biphasic and sarcomatoid) MPM are particularly resistant to therapy. We investigated the role of the GITR-GITRL pathway in mediating the resistance to therapy. We found that GITR and GITRL expressions were higher in the sarcomatoid cell line (CRL5946) than in non-sarcomatoid cell lines (CRL5915 and CRL5820), and that cisplatin and Cs-137 irradiation increased GITR and GITRL expressions on tumor cells. Transcriptome analysis demonstrated that the GITR-GITRL pathway was promoting tumor growth and inhibiting cell apoptosis. Furthermore, GITR+ and GITRL+ cells demonstrated increased spheroid formation in vitro and in vivo. Using patient derived xenografts (PDXs), we demonstrated that anti-GITR neutralizing antibodies attenuated tumor growth in sarcomatoid PDX mice. Tumor immunostaining demonstrated higher levels of GITR and GITRL expressions in non-epithelioid compared to epithelioid tumors. Among 73 patients uniformly treated with accelerated radiation therapy followed by surgery, the intensity of GITR expression after radiation negatively correlated with survival in non-epithelioid MPM patients. In conclusion, the GITR-GITRL pathway is an important mechanism of autocrine proliferation in sarcomatoid mesothelioma, associated with tumor stemness and resistance to therapy. Blocking the GITR-GITRL pathway could be a new therapeutic target for non-epithelioid mesothelioma.

Uncertainties in Radiation Doses for a Case-control Study of Thyroid Cancer among Persons Exposed in Childhood to 131 I from Chernobyl Fallout.

Uncertainties in thyroid doses due to I intake were evaluated for 2,239 subjects in a case-control study of thyroid cancer following exposure to Chernobyl fallout during childhood and adolescence carried out in contaminated regions of Belarus and Russia. Using new methodological developments that became available recently, a Monte Carlo simulation procedure was applied to calculate 1,000 alternative vectors of thyroid doses due to I intake for the study population of 2,239 subjects accounting for sources of shared and unshared errors. An overall arithmetic mean of the stochastic thyroid doses in the study was estimated to be 0.43 Gy and median dose of 0.16 Gy. The arithmetic mean and median of deterministic doses estimated previously for 1,615 of 2,239 study subjects were 0.48 Gy and 0.20 Gy, respectively. The geometric standard deviation of individual stochastic doses varied from 1.59 to 3.61 with an arithmetic mean of 1.94 and a geometric mean of 1.89 over all subjects of the study. These multiple sets of thyroid doses were used to update radiation-related thyroid cancer risks in the study population exposed to I after the Chernobyl accident.

LncRNA HOTAIR enhances breast cancer radioresistance through facilitating HSPA1A expression via sequestering miR-449b-5p.

BACKGROUND: Breast cancer (BRCA) is the leading cause of cancer-related death in women worldwide. Pre- and postoperative radiotherapy play a pivotal role in BRCA treatment but its efficacy remains limited and plagued by the emergence of radiation resistance, which aggravates patient prognosis. The long noncoding RNA (lncRNA)-implicated mechanisms underlying radiation resistance are rarely reported. The aim of this study was to determine whether lncRNA HOX transcript antisense RNA (HOTAIR) modulated the radiosensitivity of breast cancer through HSPA1A. METHODS: A Gammacell 40 Exactor was used for irradiation treatment. Bioinformatic tools and luciferase reporter assay were adopted to explore gene expression profile and demonstrate the interactions between lncRNA, miRNA and target mRNA 3'-untranslated region (3'-UTR). The expression levels of certain genes were determined by real-time PCR and western-blot analyses. in vitro and in vivo functional assays were conducted by cell viability and tumorigenicity assays. RESULTS: The levels of oncogenic lncRNA HOTAIR were positively correlated with the malignancy of BRCA but reversely correlated with the radiosensitivity of breast cancer cells. Moreover, the expression levels of HOTAIR were positively associated with those of heat shock protein family A (Hsp70) member 1A (HSPA1A) in clinical BRCA tissues and HOTAIR upregulated HSPA1A at the mRNA and protein levels in irradiated BRCA cells. Mechanistically, miR-449b-5p restrained HSPA1A expression through targeting the 3'-UTR of HSPA1A mRNA, whereas HOTAIR acted as a competing sponge to sequester miR-449b-5p and thereby relieved the miR-449b-5p-mediated HSPA1A repression. Functionally, HOTAIR conferred decreased radiosensitivity on BRCA cells, while miR-449b-5p overexpression or HSPA1A knockdown abrogated the HOTAIR-enhanced BRCA growth under the irradiation exposure both in vitro and in vivo. CONCLUSIONS: LncRNA HOTAIR facilitates the expression of HSPA1A by sequestering miR-449b-5p post-transcriptionally and thereby endows BRCA with radiation resistance. KEY POINTS: Therapeutically, HOTAIR and HSPA1A may be employed as potential targets for BRCA radiotherapy. Our findings shed new light into the mechanism by which lncRNAs modulate the radiosensitivity of tumors.

Venetoclax Synergizes with Radiotherapy for Treatment of B-cell Lymphomas.

Constitutive B-cell receptor signaling leads to overexpression of the antiapoptotic BCL-2 protein and is implicated in the pathogenesis of many types of B-cell non-Hodgkin lymphoma (B-NHL). The BCL-2 small-molecule inhibitor venetoclax shows promising clinical response rates in several lymphomas, but is not curative as monotherapy. Radiotherapy is a rational candidate for combining with BCL-2 inhibition, as DNA damage caused by radiotherapy increases the activity of pro-apoptotic BCL-2 pathway proteins, and lymphomas are exquisitely sensitive to radiation. We tested B-NHL responses to venetoclax combined with either external beam radiotherapy or radioimmunotherapy (RIT), which joins the selectivity of antibody targeting with the effectiveness of irradiation. We first tested cytotoxicity of cesium-137 irradiation plus venetoclax in 14 B-NHL cell lines representing five lymphoma subtypes. Combination treatment synergistically increased cell death in 10 of 14 lines. Lack of synergy was predicted by resistance to single-agent venetoclax and high BCL-XL expression. We then assessed the efficacy of external beam radiotherapy plus venetoclax in murine xenograft models of mantle cell (MCL), germinal-center diffuse large B-cell (GCB-DLBCL), and activated B-cell (ABC-DLBCL) lymphomas. In each model, external beam radiotherapy plus venetoclax synergistically increased mouse survival time, curing up to 10%. We finally combined venetoclax treatment of MCL and ABC-DLBCL xenografts with a pretargeted RIT (PRIT) system directed against the CD20 antigen. Optimal dosing of PRIT plus venetoclax cured 100% of mice with no detectable toxicity. Venetoclax combined with radiotherapy may be a promising treatment for a wide range of lymphomas Cancer Res; 77(14); 3885-93. ©2017 AACR.

Protective activity of a novel resveratrol analogue, HS-1793, against DNA damage in 137Cs-irradiated CHO-K1 cells.

Resveratrol has received considerable attention as a polyphenol with anti-oxidant, anti-carcinogenic, and anti-inflammatory effects. Radiation is an important component of therapy for a wide range of malignant conditions. However, it causes damage to normal cells and, hence, can result in adverse side effects. This study was conducted to examine whether HS-1793, a novel resveratrol analogue free from the restriction of metabolic instability and the high dose requirement of resveratrol, induces a protective effect against radiation-induced DNA damage. HS-1793 effectively scavenged free radicals and inhibited radiation-induced plasmid DNA strand breaks in an in vitro assay. HS-1793 significantly decreased reactive oxygen species and cellular DNA damage in 2 Gy-irradiated Chinese hamster ovary (CHO)-K1 cells. In addition, HS-1793 dose-dependently reduced the levels of phosphorylated H2AX in irradiated CHO-K1 cells. These results indicate that HS-1793 has chemical radioprotective activity. Glutathione levels and superoxide dismutase activity in irradiated CHO-K1 cells increased significantly following HS-1793 treatment. The enhanced biological anti-oxidant activity and chemical radioprotective activity of HS-1793 maintained survival of irradiated CHO-K1 cells in a clonogenic assay. Therefore, HS-1793 may be of value as a radioprotector to protect healthy tissue surrounding tumor cells during radiotherapy to obtain better tumor control with a higher dose.

Development of urinary biomarkers for internal exposure by cesium-137 using a metabolomics approach in mice.

Cesium-137 is a fission product of uranium and plutonium in nuclear reactors and is released in large quantities during nuclear explosions or detonation of an improvised device containing this isotope. This environmentally persistent radionuclide undergoes radioactive decay with the emission of beta particles as well as gamma radiation. Exposure to (137)Cs at high doses can cause acute radiation sickness and increase risk for cancer and death. The serious health risks associated with (137)Cs exposure makes it critical to understand how it affects human metabolism and whether minimally invasive and easily accessible samples such as urine and serum can be used to triage patients in case of a nuclear disaster or a radiologic event. In this study, we have focused on establishing a time-dependent metabolomic profile for urine collected from mice injected with (137)CsCl. The samples were collected from control and exposed mice on days 2, 5, 20 and 30 after injection. The samples were then analyzed by ultra-performance liquid chromatography coupled to time-of-flight mass spectrometry (UPLC/TOFMS) and processed by an array of informatics and statistical tools. A total of 1,412 features were identified in ESI(+) and ESI(-) modes from which 200 were determined to contribute significantly to the separation of metabolomic profiles of controls from those of the different treatment time points. The results of this study highlight the ease of use of the UPLC/TOFMS platform in finding urinary biomarkers for (137)Cs exposure. Pathway analysis of the statistically significant metabolites suggests perturbations in several amino acid and fatty acid metabolism pathways. The results also indicate that (137)Cs exposure causes: similar changes in the urinary excretion levels of taurine and citrate as seen with external-beam gamma radiation; causes no attenuation in the levels of hexanoylglycine and N-acetylspermidine; and has unique effects on the levels of isovalerylglycine and tiglylglycine.

Investigation of the dose- and time-dependence of the induction of different types of cell death in a small­cell lung cancer cell line: Implementation of the repairable-conditionally repairable model.

The purpose of this study was to quantify and model various types of cell death for a small-cell lung cancer (SCLC) cell line (U1690) after exposure to a 137Cs source and as well as to compare the linear-quadratic (LQ) and repairable-conditionally repairable model (RCR). This study is based on four different experiments that were taken place at Cancer Centrum Karolinska (CCK). A human small-cell lung cancer (SCLC) cell line after the exposure to a 137Cs source was used for the extraction of the clonogenic cell survival curve. Additionally, for the determination and quantification of various modes of cell death the method of fluorescence staining was implemented, where the cell deaths were categorized based on morphological characteristics. The percentage of cells in each phase of the cell cycle was investigated with flow cytometry analysis. The quantification of senescent cells was performed by staining the samples with senescence-associated ß-galactosidase (SA-ß-Gal) solution and then scoring as senescent cells those that had incorporated the substance. These data were introduced into a maximum likelihood fitting to calculate the best estimates of the parameters used by the examined model. In this model, the modes of cell death are divided into three categories: apoptotic, senescent and other types of cell death (necrotic/apoptotic, necrotic, micronuclei and giant). In the clonogenic cell survival assay, the fitting of the RCR model gives a χ(2)-value of 6.10 whereas for the LQ model became 9.61. In the fluorescence microscopy and senescence assay, the probability of the three different modes of cell death on day 2 seems to increases with a dose up to about 10 Gy where there is saturation. On day 7 a significant induction of apoptosis in a dose- and time-dependent manner was evident, whereas senescence was slightly increased in response to dose but not to time. As for the 'other types of cell death' mode on day 7 showed a higher probability than the one on day 2 and as well as a prominent dose-dependence. The RCR model fits better to the experimental data than the LQ model. On day 2 there is a slight increase of the apoptotic and senescent probability with dose. On the other hand, on day 7 the shape of the curve of apoptosis differs and a sigmoidal increase with dose is observed. At both time-points, the present model fits the data reasonably well. Due to the fact that the clonogenic survival does not coincide with the one extracted from the fluorescence microscopy, a more accurate way to quantify cell death needs to be used, e.g. computerized video time-lapse (CVTL).

Radiation-induced impacts on the degradation of 2,4-D and the microbial population in soil microcosms.

In a soil microcosm experiment, the influence of low-level (137)Cs and (90)Sr contamination on the degradation of (14)C-ring-labeled 2,4-dichlorophenoxyacetic acid (2,4-D) was studied. Two differently treated soils (one native soil and one soil sterilized and reinoculated with a biotic soil aliquot) were artificially contaminated with various concentrations of (137)Cs and (90)Sr as nitrate salts. The cumulative doses increased up to 4 Gy for 30 days of incubation in soil microcosms. Changes in microbial community structure were observed with help of the denaturing gradient gel electrophoresis (DGGE). A radiation-induced impact appeared only in the microcosms treated with 30 times the maximum contamination appearing in the exclusion zone around reactor 4 in Chernobyl. In contrast to the less contaminated soils, the mineralization of 2,4-D was delayed for 4 days before it recovered. Slight shifts in the microbial communities could be traced to radiation effects. However, other parameters had a major impact on mineralization and community structure. Thus the sterilization and reinoculation and, of course, application of the 2,4-D were predominantly reflected in the (14)CO(2) emissions and the DGGE gel patterns.

Lack of radiation dose or quality dependence of epithelial-to-mesenchymal transition (EMT) mediated by transforming growth factor ß.

PURPOSE: Epithelial-to-mesenchymal transition (EMT) is a phenotype that alters cell morphology, disrupts morphogenesis, and increases motility. Our prior studies have shown that the progeny of human mammary epithelial cells (HMECs) irradiated with 2 Gy undergoes transforming growth factor ß (TGF-ß)-mediated EMT. In this study we determined whether radiation dose or quality affected TGF-ß-mediated EMT. METHODS AND MATERIALS: HMECs were cultured on tissue culture plastic or in Matrigel (BD Biosciences, San Jose, CA) and exposed to low or high linear energy transfer (LET) and TGF-ß (400 pg/mL). Image analysis was used to measure membrane-associated E-cadherin, a marker of functional epithelia, or fibronectin, a product of mesenchymal cells, as a function of radiation dose and quality. RESULTS: E-cadherin was reduced in TGF-ß-treated cells irradiated with low-LET radiation doses between 0.03 and 2 Gy compared with untreated, unirradiated cells or TGF-ß treatment alone. The radiation quality dependence of TGF-ß-mediated EMT was determined by use of 1 GeV/amu (gigaelectron volt/atomic mass unit) (56)Fe ion particles at the National Aeronautics and Space Administration's Space Radiation Laboratory. On the basis of the relative biological effectiveness of 2 for (56)Fe ion particles' clonogenic survival, TGF-ß-treated HMECs were irradiated with equitoxic 1-Gy (56)Fe ion or 2-Gy (137)Cs radiation in monolayer. Furthermore, TGF-ß-treated HMECs irradiated with either high- or low-LET radiation exhibited similar loss of E-cadherin and gain of fibronectin and resulted in similar large, poorly organized colonies when embedded in Matrigel. Moreover, the progeny of HMECs exposed to different fluences of (56)Fe ion underwent TGF-ß-mediated EMT even when only one-third of the cells were directly traversed by the particle. CONCLUSIONS: Thus TGF-ß-mediated EMT, like other non-targeted radiation effects, is neither radiation dose nor quality dependent at the doses examined.

Ionising radiation triggers fat accumulation in white adipose tissue.

PURPOSE: To investigate changes in gonadal white adipose tissue and lipogenesis-related gene expression induced by radiation exposure. MATERIALS AND METHODS: Groups of two-month-old C57BL/6 mice were exposed whole-body to ¹³7Cs γ-rays at a single dose (5 gray [Gy]) or fractionated doses (1 Gy x 5 times, 0.5 Gy x 10 times, or 0.2 Gy x 25 times). Six months after irradiation, gonadal white adipose tissue was isolated from mice. Two and 25-month-old mice were used as young and old study references. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) was used to measure messenger RNA (mRNA) expression of genes related to: (i) Primary lipid metabolism (ATP-citrate lyase [ACL], malic enzyme1 [ME1] and glucose-6-phosphate dehydrogenase 2 [G6PD2]), (ii) glucose uptake (glucose transporter 4 [GLUT4]), (iii) fatty acid synthesis (sterol regulatory element binding transcription factor 1 [SREBP-1c], fatty acid synthetase [FAS] and acetyl-coenzyme A carboxylase beta [ACC]), (iv) triglyceride synthesis (diacylglycerol O-acyltransferase 1 [DGAT1] and diacylglycerol O-acyltransferase 2 [DGAT2]), and (v) adipose-derived hormones (leptin [LEP]). RESULTS: The weight of gonadal white adipose tissue in the irradiated groups tended to increase compared to the non-irradiated group though the radiation-induced increase in white adipose tissue was only significant for the 5 x 1 Gy group. The mRNA levels of SREBP-1c, ACC, FAS, ACL, GLUT4, ME1 and G6PD2 were relatively lower in γ-irradiated groups than in non-irradiated groups. The mRNA levels of leptin and DGAT were relatively higher than non-irradiated groups. The changes in expression of these lipogenesis-related genes caused by γ-irradiation showed a very similar pattern to changes caused by ageing. CONCLUSIONS: A physical agent such as γ-rays can trigger biological responses resulting in fat accumulation of gonadal white adipose tissue in mice.

Relationship between isotope half-life and prostatic edema for optimal prostate dose coverage in permanent seed implants.

The robustness of treatment planning to prostatic edema for three different isotopes (125I, 103Pd, and 131Cs) is explored using dynamical dose calculations on 25 different clinical prostate cases. The treatment plans were made using the inverse planning by simulated annealing (IPSA) algorithm. The prescription was 144, 127, and 125 Gy for 125I, 131Cs, and 103Pd, respectively. For each isotope, three dose distribution schemes were used to impose different protection levels to the urethra: V120 = 0%, V150 = 0%, and V150 = 30%. Eleven initial edema values were considered ranging from 1.0 (no edema) to 2.0 (100%). The edema was assumed to resolve exponentially with time. The prostate volume, seed positions, and seed activity were dynamically tracked to produce the final dose distribution. Edema decay half-lives of 10, 30, and 50 days were used. A total of 675 dynamical calculations were performed for each initial edema value. For the 125I isotope, limiting the urethra V120 to 0% leads to a prostate D90 under 140 Gy for initial edema values above 1.5. Planning with urethra V150 at 0% provides a good response to the edema; the prostate D90 remains higher than 140 Gy for edema values up to 1.8 and a half-life of 30 days or less. For 103Pd, the prostate D90 is under 97% of the prescription dose for approximately 66%, 40%, and 30% of edema values for urethra V120 = 0%, V150 = 0%, and V150 = 30%, respectively. Similar behavior is seen for 131Cs and the center of the prostate becomes "cold" for almost all edema scenarios. The magnitude of the edema following prostate brachytherapy, as well as the half-life of the isotope used and that of the edema resorption, all have important impacts on the dose distribution. The 125I isotope with its longer half-life is more robust to prostatic edema. Setting up good planning objectives can provide an adequate compromise between organ doses and robustness. This is even more important since seed misplacements will contribute to further degrade dose coverage.

Determination of the prescription dose for biradionuclide permanent prostate brachytherapy.

A model based on the linear quadratic model that has been corrected for repopulation, sublethal cell damage repair, and RBE effect has been used to determine the prescription dose for prostate permanent brachytherapy using seeds loaded with a mixture of 103Pd and 125I or a mixture of 103Pd and 131Cs. The prescription dose was determined by comparing the tumor cell survival fractions between the considered biradionuclide seed implant and one monoradionuclide seed implant chosen from 103Pd, 125I, and 131Cs. Prostate edema is included in the model. The influence of the value of the radiobiological parameters and RBE were also investigated. Two mixtures of radionuclides were considered: 103Pd0.75-125I0.25 and 103Pd0.25-131Cs0.75, where the subscripts indicate the fractions of total initial internal activity in the biradionuclide seed. These fractions were selected in order to obtain a dose distribution that lies between that of 103Pd and 125I/131Cs. As expected, the computed prescription dose values are dependent on the model parameters (edema half-life and magnitude, radiobiogical parameters, and RBE). The radionuclide used as a benchmark also has a strong impact on the derived prescribed dose. The large uncertainties in the radiobiological parameters and RBE values produce big errors in the computed prescribed dose. Averaged over the range of all the parameters and depending on the radionuclide used as a benchmark (in subscript), the derived prescription dose for the first mixture (PdI) would be: D(PdI)(Pd)=142(+15)(-16) Gy and D(PdI)(I)=142(+6)(-8) Gy; and D(PdCs)(Pd)=128(+13)(-13) Gy and D(PdCs)(Cs)=115(+6)(-7) Gy for the PdCs mixture. The uncertainties could be reduced if the radiobiological parameters and RBE value were known more accurately. However, as edema characteristics are patient dependent and can be obtained only after the treatment, an unpredictable error is unavoidable.

Dosimetric characterization of a 131Cs brachytherapy source by thermoluminescence dosimetry in liquid water.

Dosimetry measurements of a 131Cs brachytherapy source have been performed in liquid water employing thermoluminescence dosimeters. A search of the literature reveals that this is the first time a complete set of dosimetric parameters for a brachytherapy "seed" source has been measured in liquid water. This method avoids the medium correction uncertainties introduced by the use of water-equivalent plastic phantoms. To assure confidence in the results, four different sources were employed for each parameter measured, and measurements were performed multiple times. The measured dosimetric parameters presented here are based on the AAPM Task Group 43 formalism. The dose-rate constant measured in liquid water was (1.063 +/- 0.023) cGy h(-1) U(-1) and was based on the air-kerma strength standard for this source established by the National Institute of Standards and Technology. Measured values for the 2D anisotropy function and the radial dose function are presented.

[Investigation of conformational changes of DNA molecule caused by gamma-irradiation in water-ethanol solutions]. / Issledovanie konformatsionnykh izmenenii molekuly DNK v vodno-étanol'nykh rastvorakh, vyzvannykh vozdeistviem gamma-izlucheniia.

The intrinsic viscosity, optical anisotropy and spectral properties of DNA molecule gamma-irradiated with the doses of 10, 20 and 30 Gy in water-ethanol solutions with ethanol concentrations 0-6 mol/l are investigated in the work. Specific volume of DNA at all doses used shows a complex non-monotone dependence on the ethanol content with a peculiarity at the alcohol concentration corresponding to the destruction of water structure in the mixed solvent (so-called, critical concentration, 3.5 mol/l). Ethanol presence at the concentrations below the critical one protects macromolecule from the radiation action. At the alcohol concentrations larger the critical an inversion of the dose dependence of the DNA specific volume is observed. At that the equilibrium rigidity and secondary structure of macromolecule do not change noticeably. The results obtained indicate a significant role of the solvent structure in radiation damage of DNA molecule.

[The radiation-modifying capacity of xenogenic apotransferrin for the number of endogenous colony forming units in the spleen of irradiated mice]. / Radiomodifitsiruiushchie svoistva ksenogennogo apotransferrina po pokazateliu chisla éndogennykh KOE v selezenke obluchennykh myshei.

After intraperitoneal injection of 100 or 198 mg/kg of human serum apotransferrin (apo TF) to mice 1 day before acute exposure to 6 Gy of gamma-radiation, the number of endogenous CFU in spleen (CFUs) increased 2.5 or 2.6 times respectively. At a dose fo 10 mg/kg of the protein only an increasing tendency was found, whereas a dose of 1 mg/kg was inefficient. A dose of 100 mg/kg of BSA did not show any effect suggesting that non-specific immune response to alien antigen did not contribute to apo TF radiomodifying action. The following mechanisms of the apoTF radiomodifying effect are discussed: 1) the ability of the protein to inactivate Fe3+ ions that reduces the consequences of radiation oxidative stress; 2) the stimulation of proliferation of the exposed bone marrow cells by activation of Fe3+ transport or by Ca2+ mediated mechanism of mitogen signal transduction; 3) changing in the content and ratio of cyclic nucleotides by apo TF stimulation of Ca-calmodulin-dependent phosphodiesterase.

Increase of Candida cell virulence by anticancer drugs and irradiation.

The influence of anticancer drugs and irradiation on Candida cell proliferation, adherence to HeLa cells and susceptibility to antifungal drugs (amphotericin B and miconazole) and neutrophils were examined using two Candida albicans strains. After treatment with 5-fluorouracil (25 microg/ml to 250 microg/ml), cis-diammine-dichloroplatinum (10 microg/ml to 100 microg/ml), peplomycin (0.5 microg/ml to 5 microg/ml) or 137Cs (20 Gy to 40 Gy) for 3 days or more, surviving Candida cells proliferated more rapidly than did untreated control cells. Anticancer agent-pretreated Candida cells revealed an increased adhesion to HeLa cells corresponding to an increase of binding to the lectins. The concentration of half limited colony formation (IC50) of amphotericin B and miconazole was increased to near two-fold that of the control by pretreatment of Candida cells with the anticancer agents, except peplomycin, which only weakly increased IC50. In addition, the enolase and Candida acid proteinase activities in the culture supernatants were increased by pretreatment with the drugs and irradiation. Correspondingly, surviving Candida cells after these treatments were resistant to neutrophils, with a reduction to half of the killing. These results indicate that anti-cancer drugs and irradiation potentiate the virulence of Candida cells, or they eliminate Candida cells with low virulence, thereby enhancing the risk of oral and systemic candidiasis.

Repair of gamma-irradiation-induced DNA single-strand breaks in human bone marrow cells: effects of a second irradiation.

Human bone marrow mononuclear cells were isolated by density gradient centrifugation and irradiated with a 137Cs source. The extent of irradiation-induced single-strand breaks (SSBs) and alkali labile sites as well as their repair was investigated by using the alkaline single-cell gel electrophoresis (SCGE) technique, or comet assay. A dose-dependent increase in the length of DNA migration was seen when cells were exposed to 0, 2.43 and 5.43 Gy of gamma-irradiation. Complete repair of DNA SSBs was observed over 24 h after a dose of 2.43 Gy. Second challenges of 0, 2.43 and 5.43 Gy resulted in similar SSBs as with the first irradiation. Furthermore, the DNA repair kinetics of two cell populations, one previously unirradiated and the other having received 2.43 Gy 24 h earlier, was indistinguishable. This means that most human bone marrow cells retain their genetic stability after a dose of 2.43 Gy if SSBs are used as an endpoint.

Suppression by anticancer agents of reactive oxygen generation from polymorphonuclear leukocytes.

The influence of anticancer agents on signal transduction for reactive oxygen generation was examined in polymorphonuclear leukocytes (PMN). Inositol 1,4,5-trisphosphate and diacyl glycerol levels in formyl-methionyl-leucyl-phenylalanine (FMLP)-stimulated PMN were decreased by cis-diammine-dichloroplatinum (CDDP), 5-fluorouracil (5-FU), 137Cs, and peplomycin (PLM, a bleomycin analog) in this order. Intracellular calcium ([Ca2+]i) level and protein kinase C (PKC) activity in the membrane after phorbol myristate acetate (PMA) stimulation were decreased by 5-FU and CDDP but not by 137Cs and, in contrast, were increased by PLM. The level of [Ca2+]i was decreased by 8 h treatment with 5-FU and CDDP. 5-FU and CDDP inhibited tyrosine phosphorylation of 83-kDa and 115-kDa proteins, however 137Cs did not inhibit their phosphorylation and PLM enhanced the tyrosine phosphorylation. Short term (< or = 4 h) treatment with PLM, 5-FU and CDDP enhanced respiratory burst of PMN, whereas long term (8 h) treatment, as well as radiation, suppressed reactive oxygen generation from PMN in a dose dependent manner. Genistein suppressed chemiluminescence in 5-FU-, CDDP-, and 137Cs-pretreated PMN to a greater extent than it did in PLM-pretreated PMN, however near suppression of chemiluminescence by staurosporine, 4-bromophenyl bromide and methionine was observed in PMN pretreated with these agents. In conclusion, these results indicate that long term treatment of PMN with 5-FU and CDDP inhibit respiratory burst, suppressing intracellular calcium mobilization, PKC translocation and tyrosine kinase activation, in adverse, short term treatment with PLM enhances PKC translocation and tyrosine kinase activation, but inhibits myeloperoxidase (MPO) activity, and radiation causes weak inhibition of signal transduction for respiratory burst.

[The cytogenetic effects of 137Cs gamma quanta]. / Tsitogeneticheskie éffekty gamma-kvantov 137Cs.

The data on the human chromosomal level have been first obtained showing that the values of relative biological effectiveness of the 137Cs radionuclide exceed 1. These findings were allowed for during intracavitary radiotherapy in more than 50 patients with uterine body cancer.