Chronic hepatitis C patients prior to broad access to interferon-free treatments in Germany

In 2014, the first interferon-free treatment options for chronic Hepatitis C (CHC) became available in Europe introducing a new era of highly effective and well tolerated oral treatment options for CHC. The data from the cross-sectional study CURRENT-C highlights the epidemiological characteristics of patients with CHC in Germany. During the period that the study was conducted, the approval of the combination drugs for the treatment of CHC was imminent.Between June and November 2014, 1471 CHC-patients not receiving anti-HCV treatment were included nationwide in 40 German centers specializing in viral hepatitis. The mean age was 52.4 years with 41.2 % of the patients being female. Presumed route of infection in male patients was most frequently drug use (46.2 %) and blood products in females (22.8 %). The route of infection was unknown in 28.2 % of male and 43.1 % of female patients. Compared to male patients, female patients were older (55.6 vs. 50.1 years) and longer diagnosed with HCV (18 vs. 15 years). First language of the patients was most frequently German (72.2 %), followed by Russian (14.2 %), and Polish (2.9 %). HCV genotype (GT) 1 was found in 73.8 % (1a 29.0 %, 1b 38.4 %), GT2 in 3.5 %, GT3 in 18.3 %, GT4 in 4.2 %, GT5 in 0.2 %, and GT6 in 0.3 %. Liver cirrhosis was diagnosed in 15.7 % of the patients (17.1 % male, 13.7 % female). 43.2 % of the patients had already received HCV treatment, most frequently dual therapy with pegIFN + RBV (75.8 %) or triple therapy with telaprevir or boceprevir (20.3 %). Compared to treatment-naïve patients, pretreated HCV patients were older (55.1 vs. 50.3 years) and more frequently had liver cirrhosis as clinical diagnosis (22.2 % vs. 10.8 %). Patients scheduled for HCV treatment within the next 3 months had higher rates of pre-treatment (49.4 % vs. 37.0 %), and liver cirrhosis (21.4 % vs. 10.0 %).Compared to epidemiological data of Hüppe et al. 1 from 2003 to 2006, Klass et al. 2 stated in 2012 in a comparable setting that the German CHC population were older and had more advanced liver disease. The current data seem to support this ongoing trend towards more difficult to treat patients with an urgent need for new treatment options.

DNA double strand breaks as predictor of efficacy of the alpha-particle emitter Ac-225 and the electron emitter Lu-177 for somatostatin receptor targeted radiotherapy

Rationale

Key biologic effects of the alpha-particle emitter Actinium-225 in comparison to the beta-particle emitter Lutetium-177 labeled somatostatin-analogue DOTATOC in vitro and in vivo were studied to evaluate the significance of γH2AX-foci formation.

Methods

To determine the relative biological effectiveness (RBE) between the two isotopes (as - biological consequence of different ionisation-densities along a particle-track), somatostatin expressing AR42J cells were incubated with Ac-225-DOTATOC and Lu-177-DOTATOC up to 48 h and viability was analyzed using the MTT assay. DNA double strand breaks (DSB) were quantified by immunofluorescence staining of γH2AX-foci. Cell cycle was analyzed by flow cytometry. In vivo uptake of both radiolabeled somatostatin-analogues into subcutaneously growing AR42J tumors and the number of cells displaying γH2AX-foci were measured. Therapeutic efficacy was assayed by monitoring tumor growth after treatment with activities estimated from in vitro cytotoxicity.

Results

Ac-225-DOTATOC resulted in ED₅₀ values of 14 kBq/ml after 48 h, whereas Lu-177-DOTATOC displayed ED₅₀ values of 10 MBq/ml. The number of DSB grew with increasing concentration of Ac-225-DOTATOC and similarly with Lu-177-DOTATOC when applying a factor of 700-fold higher activity compared to Ac-225. Already 24 h after incubation with 2.5–10 kBq/ml, Ac-225-DOTATOC cell-cycle studies showed up to a 60% increase in the percentage of tumor cells in G2/M phase. After 72 h an apoptotic subG1 peak was also detectable. Tumor uptake for both radio peptides at 48 h was identical (7.5%ID/g), though the overall number of cells with γH2AX-foci was higher in tumors treated with 48 kBq Ac-225-DOTATOC compared to tumors treated with 30 MBq Lu-177-DOTATOC (35% vs. 21%). Tumors with a volume of 0.34 ml reached delayed exponential tumor growth after 25 days (44 kBq Ac-225-DOTATOC) and after 21 days (34 MBq Lu-177-DOTATOC).

Conclusion

γH2AX-foci formation, triggered by beta- and alpha-irradiation, is an early key parameter in predicting response to internal radiotherapy.

Rac1 protein signaling is required for DNA damage response stimulated by topoisomerase II poisons

To investigate the potency of the topoisomerase II (topo II) poisons doxorubicin and etoposide to stimulate the DNA damage response (DDR), S139 phosphorylation of histone H2AX (γH2AX) was analyzed using rat cardiomyoblast cells (H9c2). Etoposide caused a dose-dependent increase in the γH2AX level as shown by Western blotting. By contrast, the doxorubicin response was bell-shaped with high doses failing to increase H2AX phosphorylation. Identical results were obtained by immunohistochemical analysis of γH2AX focus formation, comet assay-based DNA strand break analysis, and measuring the formation of the topo II-DNA cleavable complex. At low dose, doxorubicin activated ataxia telangiectasia mutated (ATM) but not ATM and Rad3-related (ATR). Both the lipid-lowering drug lovastatin and the Rac1-specific inhibitor NSC23766 attenuated doxorubicin- and etoposide-stimulated H2AX phosphorylation, induction of DNA strand breaks, and topo II-DNA complex formation. Lovastatin and NSC23766 acted in an additive manner. They did not attenuate doxorubicin-induced increase in p-ATM and p-Chk2 levels. DDR stimulated by topo II poisons was partially blocked by inhibition of type I p21-associated kinases. DDR evoked by the topoisomerase I poison topotecan remained unaffected by lovastatin. The data show that the mechanisms involved in DDR stimulated by topo II poisons are agent-specific with anthracyclines lacking DDR-stimulating activity at high doses. Pharmacological inhibition of Rac1 signaling counteracts doxorubicin- and etoposide-stimulated DDR by disabling the formation of the topo II-DNA cleavable complex. Based on the data we suggest that Rac1-regulated mechanisms are required for DNA damage induction and subsequent activation of the DDR following treatment with topo II but not topo I poisons.

Cytoprotective effect of the small GTPase RhoB expressed upon treatment of fibroblasts with the Ras-glucosylating Clostridium sordellii lethal toxin

Mono-glucosylation of (H/K/N)Ras by Clostridium sordellii lethal toxin (TcsL) blocks critical survival signaling pathways, resulting in apoptosis. In this study, TcsL and K-Ras knock-down by siRNA are presented to result in expression of the cell death-regulating small GTPase RhoB. TcsL-induced RhoB expression is based on transcriptional activation involving p38(alpha) MAP kinase. Newly synthesized RhoB protein is rapidly degraded in a proteasome- and a caspase-dependent manner, providing first evidence for caspase-dependent degradation of a Rho family protein. Although often characterised as a pro-apoptotic protein, RhoB suppresses caspase-3 activation in TcsL-treated fibroblasts. The finding on the cytoprotective activity of RhoB in TcsL-treated cells re-enforces the concept that RhoB exhibits cytoprotective rather than pro-apoptotic activity in a cellular background of inactive Ras.

The lipid lowering drug lovastatin protects against doxorubicin-induced hepatotoxicity

Liver is the main detoxifying organ and therefore the target of high concentrations of genotoxic compounds, such as environmental carcinogens and anticancer drugs. Here, we investigated the usefulness of lovastatin, which is nowadays widely used for lipid lowering purpose, as a hepatoprotective drug following the administration of the anthracycline derivative doxorubicin in vivo. To this end, BALB/c mice were exposed to either a single high dose or three consecutive low doses of doxorubicin. Acute and subacute hepatotoxicities were analyzed with or without lovastatin co-treatment. Lovastatin protected the liver against doxorubicin-induced acute pro-inflammatory and pro-fibrotic stress responses as indicated by an attenuated mRNA expression of tumor necrosis factor alpha (TNFα) and connective tissue growth factor (CTGF), respectively. Hepatoprotection by lovastatin was due to a reduced induction of DNA damage following doxorubicin treatment. The statin also mitigated subacute anthracycline-provoked hepatotoxicity as shown on the level of doxorubicin- and epirubicin-stimulated CTGF mRNA expression as well as histopathologically detectable fibrosis and serum concentration of marker enzymes of hepatotoxicity (GPT/GLDH). Kidney damage following doxorubicin exposure was not detectable under our experimental conditions.Moreover, lovastatin showed multiple inhibitory effects on doxorubicin-triggered hepatic expression of genes involved in oxidative stress response, drug transport, DNA repair, cell cycle progression and cell death. Doxorubicin also stimulated the formation of ceramides. Ceramide production, however, was not blocked by lovastatin, indicating that hepatoprotection by lovastatin is independent of the sphingolipid metabolism. Overall, the data show that lovastatin is hepatoprotective following genotoxic stress induced by anthracyclines. Based on the data, we hypothesize that statins might be suitable to lower hepatic injury following anthracycline-based anticancer therapy.

Rac1-regulated endothelial radiation response stimulates extravasation and metastasis that can be blocked by HMG-CoA reductase inhibitors

Radiotherapy (RT) plays a key role in cancer treatment. Although the benefit of ionizing radiation (IR) is well established, some findings raise the possibility that irradiation of the primary tumor not only triggers a killing response but also increases the metastatic potential of surviving tumor cells. Here we addressed the question of whether irradiation of normal cells outside of the primary tumor augments metastasis by stimulating the extravasation of circulating tumor cells. We show that IR exposure of human endothelial cells (EC), tumor cells (TC) or both increases TC-EC adhesion in vitro. IR-stimulated TC-EC adhesion was blocked by the HMG-CoA reductase inhibitor lovastatin. Glycyrrhizic acid from liquorice root, which acts as a Sialyl-Lewis X mimetic drug, and the Rac1 inhibitor NSC23766 also reduced TC-EC adhesion. To examine the in vivo relevance of these findings, tumorigenic cells were injected into the tail vein of immunodeficient mice followed by total body irradiation (TBI). The data obtained show that TBI dramatically enhances tumor cell extravasation and lung metastasis. This pro-metastatic radiation effect was blocked by pre-treating mice with lovastatin, glycyrrhizic acid or NSC23766. TBI of mice prior to tumor cell transplantation also stimulated metastasis, which was again blocked by lovastatin. The data point to a pro-metastatic trans-effect of RT, which likely rests on the endothelial radiation response promoting the extravasation of circulating tumor cells. Administration of the widely used lipid-lowering drug lovastatin prior to irradiation counteracts this process, likely by suppressing Rac1-regulated E-selectin expression following irradiation. The data support the concern that radiation exposure might increase the extravasation of circulating tumor cells and recommend co-administration of lipid-lowering drugs to avoid this adverse effect of ionizing radiation.

Inhibition of Rac1 signaling by lovastatin protects against anthracycline-induced cardiac toxicity

Normal tissue damage limits the efficacy of anticancer therapy. For anthracyclines, the clinically most relevant adverse effect is cardiotoxicity. The mechanisms involved are poorly understood and putative cardioprotectants are controversially discussed. Here, we show that the lipid-lowering drug lovastatin protects rat H9c2 cardiomyoblasts from doxorubicin in vitro. Protection by lovastatin is related to inhibition of the Ras-homologous GTPase Rac1. It rests on a reduced formation of DNA double-strand breaks, resulting from the inhibition of topoisomerase II by doxorubicin. Doxorubicin transport and reactive oxygen species are not involved. Protection by lovastatin was confirmed in vivo. In mice, lovastatin mitigated acute doxorubicin-induced heart and liver damage as indicated by reduced mRNA levels of the pro-fibrotic cytokine connective tissue growth factor (CTGF) and pro-inflammatory cytokines, respectively. Lovastatin also protected from doxorubicin-provoked subacute cardiac damage as shown by lowered mRNA levels of CTGF and atrial natriuretic peptide. Increase in the serum concentration of troponin I and cardiac fibrosis following doxorubicin treatment were also reduced by lovastatin. Whereas protecting the heart from harmful doxorubicin effects, lovastatin augmented its anticancer efficacy in a mouse xenograft model with human sarcoma cells. These data show that statins lower the incidence of cardiac tissue injury after anthracycline treatment in a Rac1-dependent manner, without impairing the therapeutic efficacy.

Potential use of HMG-CoA reductase inhibitors (statins) as radioprotective agents

HMG-CoA reductase inhibitors (statins) are widely used in the therapy of hypercholesterolemia. Apart from their lipid-lowering activity, they have pleiotropic effects that are attributed to the inhibition of regulatory proteins, including Ras-homologous (Rho) GTPases. Here, we discuss the potential usefulness of statins to prevent normal tissue damage provoked by radiotherapy. Statins reduce the mRNA expression of pro-inflammatory and pro-fibrotic cytokines stimulated by ionizing radiation in vitro and alleviate IR-induced inflammation and fibrosis in vivo. The currently available data indicate that statins accelerate the rapid repair of DNA double-strand breaks and, moreover, mitigate the DNA damage response induced by IR. Furthermore, statins increase the mRNA expression of DNA repair factors in vivo. Thus, although the molecular mechanisms involved are still ambiguous, preclinical data concordantly show a promising radioprotective capacity of statins.

Killing of rat basophilic leukemia cells by lethal toxin from Clostridium sordellii: critical role of phosphatidylinositide 3'-OH kinase/Akt signaling

Clostridium sordellii lethal toxin (TcsL) belongs to the family of clostridial glucosylating toxins. TcsL exhibits glucosyltransferase activity to inactivate Rho and Ras proteins. On cultured cells, TcsL causes actin reorganization ("cytopathic effect") and apoptotic cell death ("cytotoxic effect"). This study is based on the concept that the cytotoxic effects of TcsL depend on the glucosylation of critical substrate proteins rather than on the glucosyltransferase activity per se. The cytotoxic effects of TcsL depend on the glucosyltransferase activity of TcsL, as neither chemically inactivated TcsL nor a glucosyltransferase-deficient mutant version of TcsL caused it. The TcsL homologous toxin B from Clostridium difficile serotype F strain 1470 (TcdBF) also failed to cause cytotoxic effects. Correlation of the toxins' respective protein substrate specificities highlighted (H/K/N)Ras as critical substrate proteins for the cytotoxic effects. (H/K/N)Ras are critical upstream regulators of phosphatidylinositide 3'-OH kinase (PI3K)/Akt survival signaling. Tauroursodeoxycholic acid (TUDCA) classified to activate PI3K/Akt signaling downstream of apoptosis-inducing stimuli prevented the cytotoxic effects of TcsL. In conclusion, (H/K/N)Ras glucosylation and subsequent inhibition of PI3K/Akt signaling are critical for the cytotoxic effects of TcsL.

Distinct kinetics of (H/K/N)Ras glucosylation and Rac1 glucosylation catalysed by Clostridium sordellii lethal toxin

Mono-glucosylation of (H/K/N)Ras by Clostridium sordellii lethal toxin (TcsL) blocks critical survival signaling pathways, resulting in apoptotic cell death. One yet unsolved problem in studies on TcsL is the lack of a method allowing the specific detection of (H/K/N)Ras glucosylation. In this study, we identify the Ras(Mab 27H5) antibody as a glucosylation-sensitive antibody capable for the immunoblot detection of (H/K/N)Ras glucosylation in TcsL-treated cells. Alternative Ras antibodies including the K-Ras(Mab F234) antibody or the v-H-Ras(Mab Y13-159) antibody recognize Ras proteins regardless of glucosylation. (H/K)Ras are further shown to be more efficaciously glucosylated by TcsL than Rac1 in rat basophilic leukemia cells as well as in a cell-free system.

Prevention of the cytopathic effect induced by Clostridium difficile Toxin B by active Rac1

Clostridium difficile Toxin B (TcdB) glucosylates low molecular weight GTP-binding proteins of the Rho subfamily and thereby causes actin re-organization (cell rounding). This "cytopathic effect" has been generally attributed to RhoA inactivation. Here we show that cells expressing non-glucosylatable Rac1-Q61L are protected from the cytopathic effect of TcdB. In contrast, cells expressing RhoA-Q63L or mock-transfected cells are fully susceptible for the cytopathic effect of TcdB. These findings are extended to the Rac1/RhoG mimic IpgB1 and the RhoA mimic IpgB2 from Shigella. Ectopic expression of IpgB1, but not IpgB2, counteracts the cytopathic effect of TcdB. These data strongly suggest that Rac1 rather than RhoA glucosylation is critical for the cytopathic effect of TcdB.

Upregulation of the immediate early gene product RhoB by exoenzyme C3 from Clostridium limosum and toxin B from Clostridium difficile

ADP-ribosylation of Rho(A,B,C) by the family of exoenzyme C3-like transferases induces reorganization of the actin cytoskeleton based on inactivation of RhoA. No data are available on the role of RhoB in C3-treated cells. In murine fibroblasts treated with the cell-permeable exoenzyme C3 from Clostridium limosum (C3), an increase in the level of RhoB was observed. This upregulation of RhoB was based on transcriptional activation, as it was responsive to inhibition by actinomycin D and accompanied by activation of the rhoB promoter. Upregulation of RhoB was not observed in cells treated with either the actin ADP-ribosylating C2 toxin from Clostridium botulinum or latrunculin B, suggesting that inactivation of Rho but not actin reorganization was required for the upregulation of RhoB. This notion was confirmed, as the Rho/Rac/Cdc42-glucosylating toxin B from Clostridium difficile (TcdB) but not the Rac/R-Ras-glucosylating variant toxin B from C. difficile strain 1470 serotype F (TcdBF) induced a strong upregulation of RhoB. Upregulation of RhoB was further observed in response to the Rac/(H-,K-,N-,R-)Ras-glucosylating lethal toxin from Clostridium sordellii. The level of active, GTP-bound RhoB was increased in TcdB-treated cells compared to untreated cells (as determined by Rhotekin pull-down assay). In contrast, no active RhoB was found in C3-treated cells. RhoB-GTP was required for the TcdB-induced apoptosis (cytotoxic effect), as this effect was responsive to inhibition by C3. In conclusion, RhoB was upregulated by Rho-/Ras-inactivating toxins, as a consequence of the inactivation of either Rho(A,B,C) or (H-,K-,N-)Ras. In TcdB-treated cells, RhoB escaped its inactivation and was required for the cytotoxic effect.

Difference in the cytotoxic effects of toxin B from Clostridium difficile strain VPI 10463 and toxin B from variant Clostridium difficile strain 1470

Glucosylation of RhoA, Rac1, and Cdc42 by Clostridium difficile toxin B from strain VPI 10463 (TcdB) results in actin reorganization (cytopathic effect) and apoptosis (cytotoxic effect). Toxin B from variant C. difficile strain 1470 serotype F (TcdBF) differs from TcdB with regard to substrate proteins, as it glucosylates Rac1 and R-Ras but not RhoA and Cdc42. In this study, we addressed the question of whether the cellular effects of the toxins depend on their protein substrate specificity. Rat basophilic leukemia (RBL) cells were synchronized using the thymidine double-block technique. We show that cells were most sensitive to the cytotoxic effect of TcdB in S phase, as analyzed in terms of phosphatidyl serine externalization, fragmentation of nuclei, and activation of caspase-3; in contrast, TcdBF induced only a marginal cytotoxic effect, suggesting that inactivation of RhoA (but not of Rac1) was required for the cytotoxic effect. The glucosylation of Rac1 was correlated to the cytopathic effect of either toxin, suggesting a close connection of the two effects. The cytotoxic effect of TcdB was executed by caspase-3, as it was responsive to inhibition by acetyl-Asp-Met-Gln-Asp-aldehyde (Ac-DMQD-CHO), an inhibitor of caspase-3. The viability of TcdB-treated RBL cells was reduced, whereas the viability of TcdBF-treated cells was unchanged, further confirming that inactivation of RhoA is required for the cytotoxic effect. In conclusion, the protein substrate specificity of the glucosylating toxins determines their biological activity.

Cellular stability of Rho-GTPases glucosylated by Clostridium difficile toxin B

Mono-glucosylation of Rho, Rac, and Cdc42 by Clostridium difficile toxin B (TcdB) induces changes of actin dynamics and apoptosis. When fibroblasts were treated with TcdB, an apparent decrease of the cellular Rac1 level was observed when applying anti-Rac1(Mab 102). This decrease was not based on degradation as inhibition of the proteasome by lactacystin did not stabilise cellular Rac1 levels. The application of anti-Rac1 (Mab 23A8) showed that the cellular Rac1 level slightly increased in TcdB-treated fibroblasts; thus, the apparent loss of cellular Rac1 was not due to degradation but due to impaired recognition of glucosylated Rac1 by anti-Rac1 (Mab 102). In contrast, recognition of RhoA by anti-RhoA (Mab 26C4) and Cdc42 by anti-Cdc42 (Mab 44) was not altered by glucosylation; a transient decrease of cellular RhoA and Cdc42 in TcdB-treated fibroblasts was indeed due to proteasomal degradation, as inhibition of the proteasome by lactacystin stabilised both cellular RhoA and Cdc42 levels. The finding that the apparent decrease of Rac1 reflects Rac1 glucosylation offers a valuable tool to determine Rac1 glucosylation.