Different Concentrations Of Bleomycin Research Articles

Usefulness of FAPα assessment in bronchoalveolar lavage as a marker of fibrogenesis: results of a preclinical study and first report in patients with idiopathic pulmonary fibrosis

BackgroundFibroblast activation protein-α (FAPα) is a marker of activated fibroblasts that can be selectively targeted by an inhibitor (FAPI) and visualised by PET/CT imaging. We evaluated whether the measurement of FAPα in bronchoalveolar lavage fluids (BALF) and the uptake of FAPI by PET/CT could be used as biomarkers of fibrogenesis.MethodsThe dynamics of lung uptake of 18F-labeled FAPI ([18F]FAPI-74) was assessed in the bleomycin mouse model at various time points and using different concentrations of bleomycin by PET/CT. FAPα was measured in BALFs from these bleomycin-treated and control mice. FAPα levels were also assessed in BALFs from controls and patients with idiopathic pulmonary fibrosis (IPF).ResultsBleomycin-treated mice presented a significantly higher uptake of [18F]FAPI-74 during lung fibrinogenesis (days 10 and 16 after instillation) compared to control mice. No significant difference was observed at initial inflammatory phase (3 days) and when fibrosis was already established (28 days). [18F]FAPI-74 tracer was unable to show a dose-response to bleomycin treatment. On the other hand, BALF FAPα levels were steeply higher in bleomycin-treated mice at day 10 and a significant dose-response effect was observed. Moreover, FAPα levels were strongly correlated with lung fibrosis as measured by the modified Aschroft histological analysis, hydroxyproline and the percentage of weight loss. Importantly, higher levels of FAPα were observed in IPF patients where the disease was progressing as compared to stable patients and controls. Moreover, patients with FAPα BALF levels higher than 192.5 pg/mL presented a higher risk of progression, transplantation or death compared to patients with lower levels.ConclusionsOur preclinical data highlight a specific increase of [18F]FAPI-74 lung uptake during the fibrotic phase of the bleomycin murine model. The measurement of FAPα in BALF appears to be a promising marker of the fibrotic activity in preclinical models of lung fibrosis and in IPF patients. Further studies are required to confirm the role of FAPα in BALF as biomarker of IPF activity and assess the relationship between FAPα levels in BALF and [18F]FAPI-74 uptake on PET/CT in patients with fibrotic lung disease.

Microwave-induced thermoacoustic microscopy based on short-pulse microwave and high-frequency point-focused ultrasonic transducer.

As an emerging hybrid imaging modality, microwave-induced thermoacoustic imaging (MITAI) provides high contrast and deep tissue penetration, and has been extensively applied in cancer diagnosis, arthritis detection, and brain research. However, the previous studies had a limited spatial resolution of about 0.45-1.5mm. Here, we describe a microwave-induced thermoacoustic microscopy (MITAM) system to help overcome the resolution limitation of current MITAI to image more subtle tissue features. On this basis, this paper applies MITAM to the thin skin and to demonstrate the potential of MITAM in detecting scleroderma. To achieve high resolution, short pulse width microwave (pulse width: 70ns) and high-frequency ultrasonic point-focused transducer (center frequency: 25MHz) were used to build the MITAM system. Two parallel copper wires with a diameter of 90μm in the X/Y plane and Y/Z plane were imaged to estimate X/Y/Z resolution. Nine Balb/c mice were randomly divided into three groups and injected with different concentrations of bleomycin to induce scleroderma models. Their ex vivo skins were then imaged by our MITAM system. Visual observations were performed on the 3-dimensional skins MITAM images. And the mean value, Standard deviation, quartile distance, and signal-to-noise ratio were calculated to verify the results of the qualitative observations. Hematoxylin-Eosin (HE) and Masson staining were used to validate the findings of the MITAM. The thickness of each imaged skin was measured to be about 450μm. As an organ composed of multiple layers of tissues, the skin needs to be imaged at high resolution for the detection of related diseases. The results obtained showed that the improved resolution (68μm in the Z-axis and 135μm in the X-axis/Y-axis) of MITAM over conventional MITAI allowed us to differentiate scleroderma skins from normal skins and to identify the severity of scleroderma skins, consistent with the pathological findings of these skins. The preliminary results obtained indicate that the MITAM can relieve the resolution limitation of traditional MITAI and has the potential to detection scleroderma. However, the transmission-type MITAM mentioned in this paper is difficult to image in vivo due to the narrow area between the antenna and the transducer. In the future, a reflective scanning MITAM will be constructed to detect scleroderma in vivo.

Chemoprotective Effect of Phyllanthus emblica Molybdenum Disulphide (MoS2) Nanoparticles on Bleomycin-Induced Cytotoxicity in Human Lymphocytes

Following the world's largest nuclear accident at Fukushima in 2011, a lot of research has been conducted to try to minimize the potential health effects of radiation exposure. One way to do this is to use natural antioxidants to protect against oxidative DNA damage. We studied the effects of an Phyllanthus emblica fruit crude extract MoS2 NPs against bleomycin-induced cytotoxicity in human lymphocytes to see if it increases the overall chemoprotective mechanism. We analyzed the frequency of micronuclei (MN) and DNA damage after treatment with different concentrations of bleomycin. We observed a significant increase in cell viability in lymphocytes treated with Phyllanthus emblica fruit crude extract MoS2 NPs and then exposed to bleomycin induced cytotoxic cells. When lymphocytes were pretreated with Phyllanthus emblica fruit crude extract MoS2 NPs (80 and 100 μg/mL), the frequency of micronuclei was decreased at all doses of bleomycin and DNA damage was decreased at 20 μg/mL of bleomycin induced cytotoxicity human lymphocytes. These results suggest that Phyllanthus emblica fruit crude extract MoS2 NPs may have chemoprotective effects by performing CBMN assay.

Downregulation of PTEN mediates bleomycin-induced premature senescence in lung cancer cells by suppressing autophagy.

ObjectiveBleomycin is an important chemotherapeutic drug that activates premature senescence to decrease the tumorigenic process. We aimed to investigate the role of phosphatase and tensin homolog deleted on chromosome ten (PTEN) in bleomycin-induced premature senescence in lung cancer cells.MethodsHuman lung cancer A549 cells were incubated in the presence of different concentrations of bleomycin for 5 days. A lentivirus vector was used to silence the PTEN gene, followed by stimulation with bleomycin (1 µg/mL). Changes were evaluated by senescence-associated β-galactosidase staining, reverse transcription-polymerase chain reaction, and western blot.ResultsTreatment with bleomycin induced premature senescence. PTEN expression was decreased and key downstream molecules in the phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway were gradually activated following bleomycin treatment. Silencing PTEN reduced autophagy and accelerated senescence of A549 cells. Autophagy levels were also increased and senescence markers were reduced after inhibiting mTOR.ConclusionsDownregulation of PTEN mediates bleomycin-induced premature senescence in lung cancer cells by suppressing autophagy via the PI3K/Akt/mTOR pathway. These findings provide new insights into the potential role of PTEN as a molecular target for cancer chemotherapy.

Intralesional injection of bleomycin in the treatment of xanthelasma palpebrarum: A clinical study.

Xanthelasma palpebrarum (XP) is the most common type of cutaneous xanthoma and has been treated with intralesional injection of pingyangmycin effectively. However, bleomycin, which has the same effect in antitumor activity as pingyangmycin, has not been applied in the treatment of XP. To explore and assess the treatment of xanthelasma by intralesional injection of bleomycin, which has been widely used as an antitumor antibiotic, for the replacement of pingyangmycin. Intralesional injection of different concentrations of bleomycin was administered to 44 xanthelasma lesions of 24 patients who have never been treated before, divided into two groups according to age. Photographs were taken and analyzed to assess the therapeutic efficiency. Patients were then followed up for 6-24months. All the lesions resolved after 1month of treatment with the intralesional injection of different concentrations of bleomycin. There was no significant difference observed between the two groups. No severe complications had occurred. The treatment of XP with intralesional injection of bleomycin is minimally invasive, safe, and effective. Consequently, it also has good cosmetic outcome with no adverse effects.

Bleomycin-induced genotoxicity in vitro in human peripheral blood lymphocytes evidenced as complex chromosome- and chromatid-type aberrations

Bleomycin is a chemotherapeutic and a radiomimetic drug which induces single and double-strand breaks in DNA by forming free radicals. We demonstrate in this study the capacity of bleomycin in inducing complex chromosome- and chromatid-type aberrations. Human peripheral blood was exposed to different concentrations of bleomycin (0, 10, 20, 30 and 40 μg/mL) and the aberrations induced were studied. The chromosomal-type aberrations studied were dicentrics, tricentrics, tetracentrics, centric rings and acentric fragments. The chromatid-type aberrations studied were double minutes, terminal lesions and terminal deletions. Though the overall trends that we obtained in the dose-dependent mitotic index and the chromosome- and chromatid-type aberrations conform to the reported literature, we could observe enhanced numbers and the types of such damages in this study. We could notice that chromosome-type aberrations were more than the chromatid-type aberrations. The enhanced numbers and the types of aberrations induced pave way for enhancing the sensitivity of genotoxic assays. Also, with more numbers and type of aberrations available, it would be useful to study the mechanisms of genotoxicity of drugs and in understanding phenomena such as “tolerance induction” to chronic exposure to such mutagens.

S100A9 aggravates bleomycin-induced dermal fibrosis in mice via activation of ERK1/2 MAPK and NF-κB pathways.

Objective(s):This study aims to investigate the pathogenicity and possible mechanisms of S100A9 function in mice models of scleroderma.Materials and Methods:The content of S100A9 in the skin tissues of mice with scleroderma was determined. Different concentrations of bleomycin (BLM) and S100A9 were subcutaneously injected into the backs of mice simultaneously, and then pathological changes in the skin of these mice were monitored. Specifically, the levels of inflammatory cytokines and alpha smooth muscle actin (α-SMA), the activation of extracellular regulated kinase 1/2 (ERK1/2), mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) pathways, and the expression of the receptor for advanced glycation end-product (RAGE) in the skin were determined.Results:The content of S100A9 in the skin tissues of mice with scleroderma was determined. Different concentrations of BLM and S100A9 were subcutaneously injected into the backs of mice simultaneously, and then pathological changes in the skin of these mice were monitored. Specifically, the levels of inflammatory cytokines and alpha smooth muscle actin (α-SMA), the activation of extracellular regulated kinase 1/2 (ERK1/2) mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) pathways, and the expression of the receptor for advanced glycation end-product (RAGE) in the skin were determined.Conclusion:S100A9 aggravates dermal fibrosis in BLM-induced scleroderma (BIS) mice, and its mechanisms might be mediated by RAGE, ERK1/2, and NF-κB pathway.

Enhancement of Bleomycin Sensitivity in Human Lung Cancer Cell Line using <i>Centella asiatica</i> Leaf Extract

Purpose: To demonstrate the effectiveness of Centella asiatica aqueous extract in augmenting the cytotoxic effect of bleomycin in the adenocarcinoma human alveolar basal epithelial A549 cell line. Methods: The inhibitory effect of bleomycin on A549 cells was determined by incubating the cells for 24 h in different concentrations of bleomycin. The effect of C. asiatica extract on A549 cells was determined after exposing cells to 5, 10, 15, 20, 25, and 30 % (v/v) bleomycin diluted from an initial 10% stock solution. Based on the 50 % inhibitory (IC 50 ) values of bleomycin, 80, 100, and 120 μg/mL concentrations were tested with 15, 20, and 25 % (v/v) of C. asiatica extract. Results: IC 50 value of bleomycin on A549 cells was 100 μg/mL, and was reduced to 80 μg/mL when cells were co-incubated with 20 % v/v of C. asiatica extract. The results show that C. asiatica extract reduces the concentration of bleomycin necessary for inhibition of A459 cell growth (IC 50 ). While the IC 50 value of bleomycin was 100 μg/ml, it fell to 80 μg/ml when used along with 20 % v/v CA extract (p < 5) Conclusions: This study demonstrates that compounds extracted from C. asiatica may have potential for use as adjuvants in bleomycin cancer chemotherapy. Keywords: Centella asiatica , A549 cells, Bleomycin, Lung cancer, Increased susceptibility, Cell viability

The effectiveness of chemotherapy and electrochemotherapy on ovarian cell lines in vitro.

The presented study aimed to evaluate in vitro the effectiveness of improvement standard chemotherapy with bleomycin by electroporation in two various ovarian cancer cell lines. Two human ovarian cell lines OvBH-1 and SKOV-3 were used. The lines were selected because of their resistance to several therapeutic methods. As anticancer drug we use range of concentrations of bleomycin. In EP and ECT experiments different voltage values: from 0 to 1200 V/cm, 8 pulses with duration of 100μs and intervals between pulses 1s long were used. The cells viability after applied treatments was evaluated by MTT assay. The expression of heat shock proteins - HSP27 was examined by immunocytochemical ABC method.The cytotoxicity with different concentrations of bleomycin alone was not significantly decrease in both cell lines. It confirms resistance of these cells to conventional chemotherapy. The highest decrease of cell proliferation was observed after EP with bleomycin after 48h of incubation for 1000 V/cm. The intensity of expression of small heat shock proteins HSP27 slightly increased after ECT in both treated cell lines, in particular in OvBH-1. The presented study indicated that application of electroporation may effectively enhance chemotherapy with bleomycin, particularly in the case of treating ovarian cancer resistant to standard therapy.

Human brain glioblastoma cells do not induce but do respond to the bleomycin-induced bystander response from lung adenocarcinoma cells

To determine whether the bleomycin (BLM)-induced bystander response occurs in human brain glioblastoma (BMG-1) cells, the BMG-1 cells were exposed to two different concentrations of BLM. The co-culture methodology was adopted to study the in vitro bystander effects. DNA damage was measured using the micronucleus (MN) and γ-H2AX assays. Cytotoxicity was measured using the trypan blue assay. Cell cycle kinetics was analyzed using flow cytometry. The overall results did not show any significant increase in either genotoxicity or cytotoxicity or a delay in the cell cycle kinetics in BMG-1 bystander cells co-cultured with BLM-exposed cells, suggesting that BLM did not induce a bystander response in the BMG-1 cells. Furthermore, the MN results of the BLM-exposed BMG-1 cells co-cultured with unexposed bystander human lung adenocarcinoma (A549 and NCI-H460) cells and vice versa suggested that the BMG-1 cells do not secrete bystander signals but do respond to those signals. Analyzing the underlying mechanism and pathways involved in preventing the cells from secreting bystander signals will provide new insights that can be applied to inhibit these mechanisms in other cell types, thereby preventing and controlling the bystander response and genomic instability and increasing the therapeutic gain in chemotherapy.

Interferon-β lipofection I. Increased efficacy of chemotherapeutic drugs on human tumor cells derived monolayers and spheroids

We evaluated the effect of hIFNβ gene transfer alone or in combination with different antineoplastic drugs commonly used in cancer treatment. Five human tumor-derived cell lines were cultured as monolayers and spheroids. Four cell lines (Ewing sarcomas EW7 and COH, melanoma M8 and mammary carcinoma MCF-7) were sensitive to hIFNβ gene lipofection. Although this effect appeared in both culture configurations, spheroids showed a relative multicellular resistance (insensitive colon carcinoma HT-29 excluded). EW7 and M8 hIFNβ-expressing cells were exposed to different concentrations of bleomycin, bortezomib, carboplatin, doxorubicin, etoposide, methotrexate, paclitaxel and vincristine in both configuration models. In chemotherapy-sensitive EW7 monolayers, the combination of hIFNβ gene and antineoplastic drugs displayed only additive or counteractive (methotrexate) effects, suggesting that cytotoxic mechanisms triggered by hIFNβ gene lipofection could be saturating the signaling pathways. Conversely, in chemotherapy-resistant EW7 spheroids or M8 cells, the combination of hIFNβ with drugs that mainly operate at the genotoxic level (doxorubicin, methotrexate and paclitaxel) presented only additive effects. However, drugs that also increase pro-oxidant species can complement the antitumor efficacy of the hIFNβ gene and clearly caused potentiated effects (bleomycin, bortezomib, carboplatin, etoposide and vincristine). The great bystander effect induced by hIFNβ gene lipofection could be among the main causes of its effectiveness, because only 1 or 2% of EW7 or M8 hIFNβ-expressing cells killed more than 60 or 80% of cell population, respectively.

Bleomycin, neocarzinostatin and ionising radiation-induced bystander effects in normal diploid human lung fibroblasts, bone marrow mesenchymal stem cells, lung adenocarcinoma cells and peripheral blood lymphocytes

Purpose: To determine whether the bystander effects induced by chemotherapeutic agents are similar to those induced by ionising radiation and to analyse the cell dependency, if any, in different human cell types such as normal lung fibroblasts (WI-38), human bone marrow mesenchymal stem cells (hBMSC), lung adenocarcinoma (A-549, NCI-H23) and peripheral blood lymphocytes (PBL).Materials and methods: The cells mentioned above were exposed to two different concentrations of bleomycin (BLM) and neocarzinostatin (NCS) and to X-irradiation. Co-culture methodology was adopted to study the in vitro bystander effects. DNA damage was measured using a micronucleus (MN) assay as an endpoint to study the bystander response. High performance liquid chromatography (HPLC) was performed to rule out any residual activity of BLM and NCS. To further investigate if this bystander response is mediated through reactive oxygen species (ROS), the bystander cells were pretreated with dimethyl sulphoxide (DMSO), an ROS scavenger, and co-cultured with cells exposed to BLM.Results: Bystander response was observed in all five types of human cells (WI-38, hBMSC, NCI-H23, A-549 and PBL) co-cultured with exposed cells. While all cell types showed a bystander response, undifferentiated hBMSC and PBL showed a higher magnitude of bystander response. A reduction in the MN frequency was observed in co-cultured hBMSC and PBL pretreated with DMSO.Conclusion: These results suggest that the chemotherapeutic agents, BLM and NCS, induce bystander response which is similar to that induced by radiation. Furthermore, it is observed that the bystander effect is independent of the cell type studied. Our results further support the involvement of ROS in mediating the bystander response induced by BLM.

Validation and application of Drosophila melanogaster as an in vivo model for the detection of double strand breaks by neutral Comet assay

Comet assay under neutral conditions allows detection of DNA double-strand breaks (DSBs), which has consequence to genome instability and carcinogenesis. The present study aims to validate the neutral Comet assay for genotoxicity assessment in Drosophila melanogaster (Oregon R +) with three well known DSBs inducers i.e. cyclophosphamide (CP), bleomycin (BLM), cisplatin (CPT) and subsequently its efficacy in detecting DSBs in the organism exposed to a well known environmental chemical, chromium [Cr(VI)]. Third instar larvae of D. melanogaster were fed different concentrations of BLM, CPT and CP (50.0–200.0 μg/ml) or Cr(VI) (5.0–20.0 μg/ml) mixed standard Drosophila food for 48 h. Neutral Comet assay was performed in cells of mid gut and brain from control and treated larvae. Our results show a dose-dependent increase in the migration of DNA in cells of the exposed organisms. A comparison among DNA lesions per mole number of the test chemical in the exposed groups showed that both BLM and CPT induce more DSBs than CP. Interestingly, Cr(VI) at 20.0 μg/ml was found to induce significantly increased ( p < 0.001) DSBs in the exposed organism as compared to the control. The study while validating neutral Comet assay in D. melanogaster suggests its use for in vivo assessment of environmental chemical induced DSBs.

Induction of complete and incomplete chromosome aberrations by bleomycin in human lymphocytes

Bleomycin (BLM) is a clastogenic compound, which due to the overdispersion in the cell distribution of induced dicentrics has been compared to the effect of high-LET radiation. Recently, it has been described that in fibroblast derived cell lines BLM induces incomplete chromosome elements more efficiently than any type of ionizing radiation. The objective of the present study was to evaluate in human lymphocytes the induction of dicentrics and incomplete chromosome elements by BLM. Peripheral blood samples have been treated with different concentrations of BLM. Two cytogenetic techniques were applied, fluorescence plus Giemsa (FPG) and FISH using pan-centromeric and pan-telomeric probes. The observed frequency of dicentric equivalents increases linearly with the BLM concentration, and for all BLM concentrations the distribution of dicentric equivalents was overdispersed. In the FISH study the ratio between total incomplete elements and multicentrics was 0.27. The overdispersion in the dicentric cell distribution, and the linear BLM-concentration dependence of dicentrics can be compared to the effect of high-LET radiation, on the contrary the ratio of incomplete elements and multicentrics is similar to the one induced by low-LET radiation (∼0.40). The elevated proportion of interstitial deletions in relation to total acentric fragments, higher than any type of ionizing radiation could be a characteristic signature of the clastogenic effect of BLM.

Naringin, a grapefruit flavanone, protects V79 cells against the bleomycin‐induced genotoxicity and decline in survival

The effect of naringin, a grapefruit flavonone was studied on bleomycin-induced genomic damage and alteration in the survival of cultured V79 cells. Exposure of V79 cells to bleomycin induced a concentration dependent elevation in the frequency of binucleate cells bearing micronuclei (MNBNC) and a maximum number of MNBNCs were observed in the cells treated with 50 microg ml(-1) bleomycin, the highest concentration evaluated. This genotoxic effect of bleomycin was reflected in the cell survival, where a concentration dependent decline was observed in the cells treated with different concentrations of bleomycin. Treatment of cells with 1 mm naringin before exposure to different concentrations of bleomycin arrested the bleomycin-induced decline in the cell survival accompanied by a significant reduction in the frequency of micronuclei when compared with bleomycin treatment alone. The cell survival and micronuclei induction were found to be inversely correlated. The repair kinetics of DNA damage induced by bleomycin was evaluated by exposing the cells to 10 microg ml(-1) bleomycin using single cell gel electrophoresis. Treatment of V79 cells with bleomycin resulted in a continuous increase in DNA damage up to 6 h post-bleomycin treatment as evident by migration of more DNA into the tails (% tail DNA) of the comets and a subsequent increase in olive tail moment (OTM), an index of DNA damage. Treatment of V79 cells with 1 mm naringin reduced bleomycin-induced DNA damage and accelerated DNA repair as indicated by a reduction in % tail DNA and OTM with increasing assessment time. A maximum reduction in the DNA damage was observed at 6 h post-bleomycin treatment, where it was 5 times lower than bleomycin alone. Our study, which was conducted on the basis of antioxidant, free radical scavenging and metal chelating properties of naringin demonstrates that naringin reduced the genotoxic effects of bleomycin and consequently increased the cell survival and therefore may act as a chemoprotective agent in clinical situations.

Are telomeres a specific target for mutagenic attack by cytostatics in neoplastic cells?

Damage to telomeres induced by cytostatic therapy theoretically could generate telomere shortening and, subsequently, induce an additional genomic instability in neoplastic cells. Model experiments were carried out to examine this hypothesis. Cells of the T-ALL derived cell line CCRF-CEM were exposed to various different concentrations of Bleomycin (BLM) or Mitomycin C (MMC) for various times. Telomere lengths of metaphase chromosomes of the exposed cells were compared with those without this exposure (controls). In addition, telomerase activity was determined with a TRAP assay under the given conditions using the BLM experiments as a model. Although slight changes of total telomere length could be found in single experiments, the differences between exposed and non-exposed cells were not significant. Also, a considerable telomerase activity was shown which, however, did not substantially differ between exposed and non-exposed cells. From these data it may be concluded that, at least in the examined cell line, telomeres are not a preferential target for this kind of mutagenic attack.

Cellular and molecular effects of bleomycin are modulated by heat shock in Saccharomyces cerevisiae

To study some mechanisms underlying the stress responses in eukaryotic cells, we investigated the effect of heat shock (HS) on the induction of DNA double strand breaks as well as on potentially lethal and mutagenic events induced by the radiomimetic antibiotic bleomycin (BLM) in Saccharomyces cerevisiae. Haploid wild-type yeast cells in the logarithmic phase of growth were exposed to different concentrations of BLM (0–30 μg/ml, 1.5 h) without and with a previous HS (38°C, 1 h). Immediately after treatments, survival as well as mutation frequency were determined, and quantitative analysis of chromosomal DNA by laser densitometry were performed both immediately after treatments and after incubation of cells during different time intervals in liquid nutrient medium free of BLM. Our results indicate that HS induces resistance to potentially lethal and mutagenic effects of BLM. Quantitative analysis of chromosomal DNA performed immediately after treatments showed the same DNA fragmentation, either upon BLM as single agent or preceded by HS. However, HS pretreated cells incubated during 4 h in liquid nutrient medium free of BLM repaired DNA double strand breaks more efficiently as compared to non-pretreated cells. On this basis, we propose that the observed HS-induced resistance to BLM depends on a regulatory network acting after DNA-induced damage, which includes genes involved in DNA repair, HS response and DNA metabolism.

Effects of bleomycin on 14C-proline uptake, its incorporation into proteins and hydroxylation in collagenous proteins of hamster lung slices.

The uptake of 14C-proline by lung slices and its incorporation into trichloroacetic-acid (TCA)-insoluble proteins and hydroxylation in collagenous proteins were studied. They were found to be linearly increased with the incubation time for as long as 8 h. The effects of different concentrations of bleomycin on these parameters were subsequently investigated. Bleomycin at 10(-3) M significantly reduced the uptake of 14C-proline to 75% of the control value. The incorporation of 14C-proline into TCA-insoluble proteins was reduced to 84%, 78% and 75% of the control at 2.5 X 10(-4) M, 5 X 10(-4) M and 10(-3) M concentrations of bleomycin, respectively. Bleomycin failed to alter the proline pool size of the lung slices at any of these concentrations. In addition, bleomycin also inhibited the hydroxylation of 14C-proline into collagen to 72% and 69% of the control at 5 X 10(-4) M and 10(-3) M, respectively. These findings show that bleomycin-induced increases in collagen synthesis in vivo is probably secondary to inflammatory reactions of the lung and bleomycin per se has little effect on increased collagen synthesis responsible for lung fibrosis.

DNA replication and repair in ataxia telangiectasia cells exposed to bleomycin

A marked increase in sensitivity to bleomycin was observed in two ataxia telangiectasia (AT) lymphoblastoid cell lines compared to that in cell lines from two normal individuals. This sensitivity was obtained at two different concentrations of bleomycin. While normal cells showed a rapid recovery of ability to divide, there was no indication of such a recovery in AT cells up to 120 h after bleomycin treatment. A similar level of breakage of DNA occurred in both cell types after incubation with bleomycin. The rate of repair of these breaks was also the same. DNA synthesis was found to be more resistant to bleomycin in AT cells than in control cells. The latter data are in keeping with results previously obtained using ionizing radiation.