Amyloid precursor protein induces reactive astrogliosis

AIM

Astrocytes respond to stressors by acquiring a reactive state characterized by changes in their morphology and function. Molecules underlying reactive astrogliosis, however, remain largely unknown. Given that several studies observed increase in the Amyloid Precursor Protein (APP) in reactive astrocytes, we here test whether APP plays a role in reactive astrogliosis.

METHODS

We investigated whether APP instigates reactive astroglios by examining in vitro and in vivo the morphology and function of naive and APP-deficient astrocytes in response to APP and well-established stressors.

RESULTS

Overexpression of APP in cultured astrocytes led to remodeling of the intermediate filament network, enhancement of cytokine production, and activation of cellular programs centered around the interferon (IFN) pathway, all signs of reactive astrogliosis. Conversely, APP deletion abrogated remodeling of the intermediate filament network and blunted expression of IFN-stimulated gene products in response to lipopolysaccharide. Following traumatic brain injury (TBI), mouse reactive astrocytes also exhibited an association between APP and IFN, while APP deletion curbed the increase in glial fibrillary acidic protein observed canonically in astrocytes in response to TBI.

CONCLUSIONS

The APP thus represents a candidate molecular inducer and regulator of reactive astrogliosis. This finding has implications for understanding pathophysiology of neurodegenerative and other diseases of the nervous system characterized by reactive astrogliosis and opens potential new therapeutic avenues targeting APP and its pathways to modulate reactive astrogliosis.

Amyloid precursor protein induces reactive astrogliosis

We present in vitro and in vivo evidence demonstrating that Amyloid Precursor Protein (APP) acts as an essential instigator of reactive astrogliosis. Cell-specific overexpression of APP in cultured astrocytes led to remodelling of the intermediate filament network, enhancement of cytokine production and activation of cellular programs centred around the interferon (IFN) pathway, all signs of reactive astrogliosis. Conversely, APP deletion in cultured astrocytes abrogated remodelling of the intermediate filament network and blunted expression of IFN stimulated gene (ISG) products in response to lipopolysaccharide (LPS). Following traumatic brain injury (TBI), mouse reactive astrocytes also exhibited an association between APP and IFN, while APP deletion curbed the increase in glial fibrillary acidic protein (GFAP) observed canonically in astrocytes in response to TBI. Thus, APP represents a molecular inducer and regulator of reactive astrogliosis.

Actionable cancer vulnerability due to translational arrest, p53 aggregation and ribosome biogenesis stress evoked by the disulfiram metabolite CuET

Drug repurposing is a versatile strategy to improve current therapies. Disulfiram has long been used in the treatment of alcohol dependency and multiple clinical trials to evaluate its clinical value in oncology are ongoing. We have recently reported that the disulfiram metabolite diethyldithiocarbamate, when combined with copper (CuET), targets the NPL4 adapter of the p97VCP segregase to suppress the growth of a spectrum of cancer cell lines and xenograft models in vivo. CuET induces proteotoxic stress and genotoxic effects, however important issues concerning the full range of the CuET-evoked tumor cell phenotypes, their temporal order, and mechanistic basis have remained largely unexplored. Here, we have addressed these outstanding questions and show that in diverse human cancer cell models, CuET causes a very early translational arrest through the integrated stress response (ISR), later followed by features of nucleolar stress. Furthermore, we report that CuET entraps p53 in NPL4-rich aggregates leading to elevated p53 protein and its functional inhibition, consistent with the possibility of CuET-triggered cell death being p53-independent. Our transcriptomics profiling revealed activation of pro-survival adaptive pathways of ribosomal biogenesis (RiBi) and autophagy upon prolonged exposure to CuET, indicating potential feedback responses to CuET treatment. The latter concept was validated here by simultaneous pharmacological inhibition of RiBi and/or autophagy that further enhanced CuET's tumor cytotoxicity, using both cell culture and zebrafish in vivo preclinical models. Overall, these findings expand the mechanistic repertoire of CuET's anti-cancer activity, inform about the temporal order of responses and identify an unorthodox new mechanism of targeting p53. Our results are discussed in light of cancer-associated endogenous stresses as exploitable tumor vulnerabilities and may inspire future clinical applications of CuET in oncology, including combinatorial treatments and focus on potential advantages of using certain validated drug metabolites, rather than old, approved drugs with their, often complex, metabolic profiles.

Cannabis-derived products antagonize platinum drugs by altered cellular transport

Cannabinoids, a class of compounds derived from Cannabis sativa L., have recently become more widely accessible for public consumption in the form of diverse cannabis products, in parallel with weakening the measures that so far restricted their availability. The US Food and Drug Administration has approved several cannabis-derived drugs for management of various diseases as well as chemotherapy-induced nausea and vomiting. Besides the attenuation of adverse effects of chemotherapy, numerous reports about cannabinoid-mediated anticancer effects further motivate cancer patients to support their therapy with such products. Here we present a set of preclinical data with human cell culture models, suggesting that cannabidiol and cannabis extracts may effectively counteract the anticancer effects of the clinically widely used standard-of-care platinum-based drugs. We show that even low concentrations of cannabinoids reduced the toxicity of cisplatin, oxaliplatin, and carboplatin, an effect which was accompanied by decreased platinum adduct formation and a set of commonly used molecular markers. Mechanistically, our results excluded the possibility that the observed enhanced survival of cancer cells was mediated transcriptionally. Instead, trace metal analyses strongly indicate an inhibitory impact of cannabinoids on intracellular platinum accumulation, thereby implicating changes in cellular transport and/or retention of these drugs as the likely cause of the observed biological effects. Our study raises the possibility that the desirable effect of counteracting adverse effects of chemotherapy might, at least for some cannabinoids, reflect impaired cellular availability, and consequently attenuation of the anticancer effects of platinum drugs. DATA AVAILABILITY: All data supporting the conclusions are available in the article and supplementary files. Raw data are available upon request from the corresponding author.

Abstract 2329: Disulfiram metabolite modulates NK and T cell cytotoxicity against metastatic colorectal cancer through tumor derived NKG2D ligands

Introduction: Colorectal cancer (CRC) is the second leading cause of cancer-related death worldwide, contributing to one million deaths yearly. While survival is expected in early-stage disease, the 5-year survival rate is only 15% in metastatic CRC (mCRC). Frequently patients develop resistance to their chemotherapy regimens resulting in CRC metastatic lesions to appear in the lungs, liver, and brain. In recent years, the development of immunotherapy has become a promising avenue for the treatment of cold-tumor environments such as CRC. Indeed, dense infiltration of lymphocytes in CRC correlates with longer patient survival. Thus, patients suffering from mCRC would benefit from the combination of classical chemotherapy/radiotherapy with small immunomodulatory molecules capable of overcoming cancer cell resistance to therapy through chemo- and radio-sensitization. Recently, Antabuse’s metabolite dithiocarb-copper complex (CuET) was found to have anti-cancer activity. Here, we report for the first time on the immunomodulatory properties of CuET in the context of T/NK cell antitumor response in mCRC.

Methods: To assess CuET anticancer activity in vitro, we performed survival curve, colony-formation, and migration-invasion assays in the murine colorectal cancer cell lines MC-38 and CT-26, and in the human KRAS mutant HCT116 cell line. We assessed in vivo efficacy of CuET in ectopic and metastatic MC-38 and CT-26 models in respective C57BL/6 and BALB/c mice. We characterized tumor growth, mice survival, and tumor immunohistochemistry. We evaluated CuET’s immunomodulatory properties through immunophenotyping of mouse and human T/NK cell receptors as well as corresponding tumor cell ligands after CuET treatment. We assessed CuET’s effect on the functional anticancer cytotoxicity of human PBMC-derived T/NK cells.

Results: In vitro, CuET significantly inhibits viability, clonogenicity, and migration of tumor cells MC-38, CT-26, and HCT116 with IC50 values in the nanomolar range. In vivo, systemic treatment with CuET significantly reduces tumor growth in mice and prolongs survival (p=0.0041) when compared to controls. CuET significantly inhibits MC-38 liver metastasis growth in C57BL/6 mice. CuET recruits macrophages and T lymphocytes inside tumor cores and induces apoptosis. CuET induces the expression of NKG2D activating receptors in NK and T lymphocytes, as well as the expression of the corresponding ligands MICA/B and ULBP1/2 on tumor cells, enhancing the T/NK cell cytotoxic response anticancer.

Conclusion: CuET enhances the functional antitumor cytotoxic activity of NK and T lymphocytes in mice and in human PBMC. In summary, our findings demonstrate that Antabuse-derived copper-diethyldithiocarbamate, CuET, is a potent immunomodulator which could benefit patients with mCRC.

Citation Format: Daciana Catalina Dumut, Ivo Frydrych, Miroslav Popper, Dusan Garic, Radu Alexandru Paun, Amanda Centorame, Olivia Canavan, Juhi Shah, Martin Mistrik, Petr Dzubak, Jiri Bartek, Marian Hajduch, Juan Bautista DeSanctis, Danuta Radzioch. Disulfiram metabolite modulates NK and T cell cytotoxicity against metastatic colorectal cancer through tumor derived NKG2D ligands [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2329.

Abstract 4935: Cannabidiol and cannabis extract protect cells against platinum-based chemotherapy via cellular uptake

Cannabinoids including cannabidiol belong between constituents of cannabis sp. (marijuana plant). Purified or as a part of cannabis products, the compounds are frequently used by cancer patients to attenuate chemotherapy-induced side effects such as pain, nausea, and vomiting. The presence of cannabis products on the public market expands each year while the illegality status weakens in an increasing number of countries. U.S. Food and Drug Administration has approved several cannabis-based drugs for seizures induced by Lennox-Gastaut syndrome, Dravet syndrome, or tuberous sclerosis complex, also for the lost appetite of AIDS patients, and chemotherapy-induced nausea and vomiting. Oncological patients are further and strongly motivated to take the drugs in combination with chemotherapy by numerous reports demonstrating the anticancer effects of cannabinoids. Nevertheless, here we present unsettling data that cannabis extract together with CBD negatively interferes with worldwide approved platinum-based drugs cisplatin, carboplatin, and oxaliplatin. The phenomenon is proven across three cellular models including primary cells. Even low concentrations of cannabidiol or cannabis extract reduced the toxicity of platinum-based drugs using long-term colony forming assay and/or short-term crystal violet assay. Increased resistance of cells was also accompanied by decreased cellular stress as evaluated by quantitative immunofluorescence microscopy and immunoblotting. Most importantly, concomitant cannabidiol and cisplatin exposure results in the decreased presence of cisplatin-modified DNA. Following the information, we determined platinum content in cells by ICP-MS. The experiment uncovered significantly decreased intracellular platinum content indicating an effect on cellular transport. Furthermore, the mechanism is translational independent as shown by the experiment with cycloheximide. This study offers crucial information that patients and physicians should take into account regarding possible interactions between platinum-based drugs and cannabis-based products. Furthermore, the study on the contradictory effects of cannabis products in cancer treatment may be motivated by this project.

Citation Format: Tereza Buchtová, Lucie Beresova, Katarina Chroma, Martin Mistrik. Cannabidiol and cannabis extract protect cells against platinum-based chemotherapy via cellular uptake. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4935.

Drug-Drug Interactions of Cannabidiol with Standard-of-Care Chemotherapeutics

Cannabidiol (CBD) is an easily accessible and affordable Marijuana (Cannabis sativa L.) plant derivative with an extensive history of medical use spanning thousands of years. Interest in the therapeutic potential of CBD has increased in recent years, including its anti-tumour properties in various cancer models. In addition to the direct anticancer effects of CBD, preclinical research on numerous cannabinoids, including CBD, has highlighted their potential use in: (i) attenuating chemotherapy-induced adverse effects and (ii) enhancing the efficacy of some anticancer drugs. Therefore, CBD is gaining popularity as a supportive therapy during cancer treatment, often in combination with standard-of-care cancer chemotherapeutics. However, CBD is a biologically active substance that modulates various cellular targets, thereby possibly resulting in unpredictable outcomes, especially in combinations with other medications and therapeutic modalities. In this review, we summarize the current knowledge of CBD interactions with selected anticancer chemotherapeutics, discuss the emerging mechanistic basis for the observed biological effects, and highlight both the potential benefits and risks of such combined treatments. Apart from the experimental and preclinical results, we also indicate the planned or ongoing clinical trials aiming to evaluate the impact of CBD combinations in oncology. The results of these and future trials are essential to provide better guidance for oncologists to judge the benefit-versus-risk ratio of these exciting treatment strategies. We hope that our present overview of this rapidly advancing field of biomedicine will inspire more preclinical and clinical studies to further our understanding of the underlying biology and optimize the benefits for cancer patients.

Allogeneic hematopoietic cell transplant for hairy cell leukemia: EBMT experience

Not available.

One-Step Synthesis of Nanoliposomal Copper Diethyldithiocarbamate and Its Assessment for Cancer Therapy

The metal complex copper diethyldithiocarbamate (CuET) induces cancer cell death by inhibiting protein degradation and induces proteotoxic stress, making CuET a promising cancer therapeutic. However, no clinical formulation of CuET exists to date as the drug is insoluble in water and exhibits poor bioavailability. To develop a scalable formulation, nanoliposomal (LP) CuET was synthesized using ethanol injection as a facile one-step method that is suitable for large-scale manufacturing. The nanoparticles are monodispersed, colloidally stable, and approximately 100 nm in diameter with an encapsulation efficiency of over 80%. LP-CuET demonstrates excellent stability in plasma, minimal size change, and little drug release after six-month storage at various temperatures. Additionally, melanoma cell lines exhibit significant sensitivity to LP-CuET and cellular uptake occurs predominantly through endocytosis in YUMM 1.7 cancer cells. Intracellular drug delivery is mediated by vesicle acidification with more nanoparticles being internalized by melanoma cells compared with RAW 264.7 macrophages. Additionally, the nanoparticles preferentially accumulate in YUMM 1.7 tumors where they induce cancer cell death in vivo. The development and characterization of a stable and scalable CuET formulation illustrated in this study fulfils the requirements needed for a potent clinical grade formulation.

Nociceptin/orphanin FQ opioid receptor (NOP) selective ligand MCOPPB links anxiolytic and senolytic effects

Accumulation of senescent cells may drive age-associated alterations and pathologies. Senolytics are promising therapeutics that can preferentially eliminate senescent cells. Here, we performed a high-throughput automatized screening (HTS) of the commercial LOPAC®Pfizer library on aphidicolin-induced senescent human fibroblasts, to identify novel senolytics. We discovered the nociceptin receptor FQ opioid receptor (NOP) selective ligand 1-[1-(1-methylcyclooctyl)-4-piperidinyl]-2-[(3R)-3-piperidinyl]-1H-benzimidazole (MCOPPB, a compound previously studied as potential anxiolytic) as the best scoring hit. The ability of MCOPPB to eliminate senescent cells in in vitro models was further tested in mice and in C. elegans. MCOPPB reduced the senescence cell burden in peripheral tissues but not in the central nervous system. Mice and worms exposed to MCOPPB also exhibited locomotion and lipid storage changes. Mechanistically, MCOPPB treatment activated transcriptional networks involved in the immune responses to external stressors, implicating Toll-like receptors (TLRs). Our study uncovers MCOPPB as a NOP ligand that, apart from anxiolytic effects, also shows tissue-specific senolytic effects.

An efficient, non-invasive approach for in-vivo sampling of hair follicles: design and applications in monitoring DNA damage and aging

In accordance with the 3 Rs principle (to replace, reduce and refine) animal models in biomedical research, we have developed and applied a new approach for sampling and analyzing hair follicles in various experimental settings. This involves use of a convenient device for non-invasive collection of hair follicles and processing methods that provide sufficient amounts of biological material to replace stressful and painful biopsies. Moreover, the main components of hair follicles are live cells of epithelial origin, which are highly relevant for most types of malignant tumors, so they provide opportunities for studying aging-related pathologies including cancer. Here, we report the successful use of the method to obtain mouse hair follicular cells for genotyping, quantitative PCR, and quantitative immunofluorescence. We present proof of concept data demonstrating its utility for routine genotyping and monitoring changes in quality and expression levels of selected proteins in mice after gamma irradiation and during natural or experimentally induced aging. We also performed pilot translation of animal experiments to human hair follicles irradiated ex vivo. Our results highlight the value of hair follicles as biological material for convenient in vivo sampling and processing in both translational research and routine applications, with a broad range of ethical and logistic advantages over currently used biopsy-based approaches.

Cannabidiol-induced activation of the metallothionein pathway impedes anticancer effects of disulfiram and its metabolite CuET

Disulfiram (DSF), an established alcohol‐aversion drug, is a candidate for repurposing in cancer treatment. DSF’s antitumor activity is supported by preclinical studies, case reports, and small clinical trials; however, ongoing clinical trials of advanced‐stage cancer patients encounter variable results. Here, we show that one reason for the inconsistent clinical effects of DSF may reflect interference by other drugs. Using a high‐throughput screening and automated microscopy, we identify cannabidiol, an abundant component of the marijuana plant used by cancer patients to mitigate side effects of chemotherapy, as a likely cause of resistance to DSF. Mechanistically, in cancer cells, cannabidiol triggers the expression of metallothioneins providing protective effects by binding heavy metal‐based substances including the bis‐diethyldithiocarbamate‐copper complex (CuET). CuET is the documented anticancer metabolite of DSF, and we show here that the CuET’s anticancer toxicity is effectively neutralized by metallothioneins. Overall, this work highlights an example of undesirable interference between cancer therapy and the concomitant usage of marijuana products. In contrast, we report that insufficiency of metallothioneins sensitizes cancer cells toward CuET, suggesting a potential predictive biomarker for DSF repurposing in oncology.

Cardiovascular events and atherogenic lipid profile in chronic myeloid leukemia patients treated with nilotinib versus imatinib

OBJECTIVES

The aim of this study was to assess cardiotoxicity and potential adverse effects related to lipid metabolism during treatment with tyrosine kinase inhibitors (TKIs) imatinib and nilotinib in patients with chronic myeloid leukemia (CML).

PATIENTS AND METHODS

Eighty-two consecutive patients with CML, who received nilotinib and/or imatinib in a single haemato-oncological Slovak center between years 2002-2018 were evaluated in a retrospective study. The mean age was 55.8 years (range 22-77 years). Median of follow-up was 61.3 months.

RESULTS

A significantly higher incidence of dyslipidemia, significantly higher levels of potential risk markers of cardiovascular disease small dense LDL cholesterol (sdLDL-CH) and a significant increase in total cholesterol were found in the patients during treatment with nilotinib in comparison to imatinib. Dyslipidemia led to drug therapy in 22 % of the patients in the nilotinib group. Fourteen percent of the patients in the nilotinib group had one or more cardiovascular events, including peripheral artery disease (10 %), myocardial infarction (4 %) and stroke (4 %).

CONCLUSION

A higher risk of cardiovascular events and atherogenic dyslipidemia were associated with nilotinib therapy. Patients treated with TKI, especially nilotinib, require an early modification of cardiovascular risk factors and a careful cardiologic surveillance so that antileukemic therapy with this highly effective agent could continue (Tab. 4, Fig. 3, Ref. 32). Text in PDF www.elis.sk Keywords: tyrosine kinase inhibitors, cardiovascular events, dyslipidemia, small dense LDL-cholesterol, nilotinib, imatinib.

Abstract 1251: Dithiocarb-copper complex, CuET, demonstrates anti-neoplastic activity in mouse model of prostate cancer and prevents recurrence of tumors

INTRODUCTION Prostate cancer (PCa) is the most common cancer in the North-American man. It was responsible for about 192,000 new cases and 33,000 deaths in the USA in 2020. Surgical resection and systemic androgen deprivation therapy are standard approaches to treat both localized and metastatic PCa (mPCa). The five-year survival from prostate cancer (PCa) without bone metastasis is 56% versus 3% with metastasis There is no cure for the metastatic prostate cancer (mPCa) which often spreads to the hip, spine, and pelvis bones. Therefore, new approaches and combination therapy need to be developed to improve patients's survival. Disulfiram's anti-cancer activity was previously explored and its metabolite ditiocarb-copper complex (CuET) was found to have high anti-cancer activity. The mechanism of action of CuET involves NPL4 aggregation and activation of ER stress, leading to preferential apoptosis of cancer cells. Since altered protein degradation is targeted by CuET, it might display high efficacy in highly mutated PCa. Consequently, we want to propose CuET for the treatment of mPCa.

METHODS Survival curve and colony-formation assays in murine dKO cell line harboring PTEN and Rb driver mutations as well as in the human metastatic PC3 cell line, were performed. Anti-metastatic effect of CuET in vitro was assessed through Boyden chamber. In vivo efficacy of systemic treatment with CuET, was studied in dKO model of C57BL/6 mice.

RESULTS Our results demonstrate that CuET displays cytotoxicity in dKO and PC3 cells at very low concentrations with respective IC50 of 46.2nM and 90.5nM. In vitro, CuET significantly reduced both the clonogenicity and migration ability of cells. In vivo, systemic treatment with CuET significantly reduced growth of dKO tumor and prevented recurrence of tumors.

CONCLUSION Given these positive pre-clinical results, CuET should be investigated for its antineoplastic activity in clinical setting as an adjuvant therapy for mPCa.

Citation Format: Daciana Catalina Dumut, Juan B. DeSanctis, Martin Mistrik, Zdenek Skrott, Petr Dzubak, Jiri Bartek, Marian Hajduch, Danuta Radzioch. Dithiocarb-copper complex, CuET, demonstrates anti-neoplastic activity in mouse model of prostate cancer and prevents recurrence of tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1251.

Treatment of Adults and Young Adults with Acute Lymphoblastic Leukemia: Real Life Data from Two Centers in Slovakia

INTRODUCTION

The results of treatment of acute lymphoblastic leukemia (ALL) from the low population countries are missing in the literature.

PATIENTS AND METHODS

We retrospectively examined biological characteristics and survival of 90 patients with ALL.

RESULTS

At median follow-up 17 months, 52 men and 38 women were eligible for the analysis with median age 43 years (18-74). As for the risk stratification, 25.6% of patients were in standard risk, 46.7% in high risk and 27.8% in very high-risk group. Complete remission achieved 88.9% of patients. We observed 5.6% of induction deaths and 4.5% of resistant disease. 47.8% of the patients underwent allogeneic stem cell transplantation (alloSCT), 59% in the young adults (YA; < 40 years) and 40% in adult group (≥ 40 years). We noticed 32.6% relapses overall with median survival of relapsed patients 3.9 months. YA patients had longer survival than adults: 3-year overall survival (OS) 65.0% vs 30.2%; (HR = 0.36; 95% CI 0.2-0.64; P = .001) and event free survival (EFS) 51.5% vs 21.9%; (HR = 0.45; 95% CI 0.26-0.78; P = .005). There was significant difference in 3-year EFS between risk groups in YA patients 90.9%, 48.0%, 11.4%; (P = .001). OS after alloSCT individually for the YA was 62.6% and for adults 39.1%, hazard ratio (HR) = 0.49 (95% CI 0.20-1.21); (P = .095). We observed 14% early deaths, 25.6% late deaths and 3 relapses (7%) after allogeneic stem cell transplantation.

CONCLUSIONS

Our data proved that even in a low population country similar result can be achieved as in larger ones while using well designed adapted protocols from leukemic study groups.

Skp2 and Slug Are Coexpressed in Aggressive Prostate Cancer and Inhibited by Neddylation Blockade

Prostate cancer (PCa) is the second leading cause of cancer-related deaths in men in Western countries, and there is still an urgent need for a better understanding of PCa progression to inspire new treatment strategies. Skp2 is a substrate-recruiting component of the E3 ubiquitin ligase complex, whose activity is regulated through neddylation. Slug is a transcriptional repressor involved in the epithelial-to-mesenchymal transition, which may contribute to therapy resistance. Although Skp2 has previously been associated with a mesenchymal phenotype and prostate cancer progression, the relationship with Slug deserves further elucidation. We have previously shown that a high Gleason score (≥8) is associated with higher Skp2 and lower E-cadherin expression. In this study, significantly increased expression of Skp2, AR, and Slug, along with E-cadherin downregulation, was observed in primary prostate cancer in patients who already had lymph node metastases. Skp2 was slightly correlated with Slug and AR in the whole cohort (Rs 0.32 and 0.37, respectively), which was enhanced for both proteins in patients with high Gleason scores (Rs 0.56 and 0.53, respectively) and, in the case of Slug, also in patients with metastasis to lymph nodes (Rs 0.56). Coexpression of Skp2 and Slug was confirmed in prostate cancer tissues by multiplex immunohistochemistry and confocal microscopy. The same relationship between these two proteins was observed in three sets of prostate epithelial cell lines (PC3, DU145, and E2) and their mesenchymal counterparts. Chemical inhibition of Skp2, but not RNA interference, modestly decreased Slug protein in PC3 and its docetaxel-resistant subline PC3 DR12. Importantly, chemical inhibition of Skp2 by MLN4924 upregulated p27 and decreased Slug expression in PC3, PC3 DR12, and LAPC4 cells. Novel treatment strategies targeting Skp2 and Slug by the neddylation blockade may be promising in advanced prostate cancer, as recently documented for other aggressive solid tumors.

Feasibility and Outcomes of a Third Allogeneic Hematopoietic Stem Cell Transplantation: A Retrospective Analysis from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Few therapeutic options are available for patients with acute myeloid or lymphoblastic leukemia (AML/ALL) relapsing after a second allogeneic stem cell transplantation (alloSCT2). In selected patients a third allogeneic stem cell transplantation (alloSCT3) has been used, but no detailed analysis is available so far. The European Society for Blood and Marrow Transplantation (EBMT) registry was screened for patients with acute leukemia (AL) receiving alloSCT3 from an identical or alternative donor to treat AL in either haematological relapse or disease persistence after alloSCT2 between 2001 and 2018. Feasibility, efficacy, outcome, and risk factors of this approach were analyzed retrospectively. Forty-five patients (median age, 37 years, range 12-71) with AML (n=34) or ALL (n=11) were identified. Eleven patients received alloSCT3 in complete remission (CR), 34 had active disease. Fifteen patients were transplanted from the same donor at all three transplants, 30 patients had at least 2 different donors. Between alloSCT2 and alloSCT3, the donor was changed in 25 patients. After alloSCT3, 38 patients engrafted, and 26 achieved CR or CR with incomplete hematological reconstitution (CRi). Acute graft-versus-host disease (GvHD) grade II-IV was observed in 19%, chronic GvHD occurred in 13%. After 1-year, cumulative incidences of leukemia relapse and non-relapse mortality were 47% and 42%, respectively. Median progression free and overall survival (PFS/OS) from alloSCT3 were 2.5 and 4 months, respectively, 1-year PFS and OS were 11% and 20%,. Outcome was improved in patients with at least one donor change (1-year PFS/OS: 17%/30%), further factors for better outcome included an unrelated donor for alloSCT3, Karnofsky performance score >80, and more recent year of alloSCT3. Only patients with AML achieved >1 year OS. In conclusion, results after a third alloSCT are poor, limiting this procedure to few, highly selected patients. Recurrent relapses of acute leukemia after alloSCT remain an unmet therapeutic need.

Microthermal-induced subcellular-targeted protein damage in cells on plasmonic nanosilver-modified surfaces evokes a two-phase HSP-p97/VCP response

Despite proteotoxic stress and heat shock being implicated in diverse pathologies, currently no methodology to inflict defined, subcellular thermal damage exists. Here, we present such a single-cell method compatible with laser-scanning microscopes, adopting the plasmon resonance principle. Dose-defined heat causes protein damage in subcellular compartments, rapid heat-shock chaperone recruitment, and ensuing engagement of the ubiquitin-proteasome system, providing unprecedented insights into the spatiotemporal response to thermal damage relevant for degenerative diseases, with broad applicability in biomedicine. Using this versatile method, we discover that HSP70 chaperone and its interactors are recruited to sites of thermally damaged proteins within seconds, and we report here mechanistically important determinants of such HSP70 recruitment. Finally, we demonstrate a so-far unsuspected involvement of p97(VCP) translocase in the processing of heat-damaged proteins. Overall, we report an approach to inflict targeted thermal protein damage and its application to elucidate cellular stress-response pathways that are emerging as promising therapeutic targets.

Survival benefit of ixazomib, lenalidomide and dexamethasone (IRD) over lenalidomide and dexamethasone (Rd) in relapsed and refractory multiple myeloma patients in routine clinical practice

BACKGROUND

We have performed a head to head comparison of all-oral triplet combination of ixazomib, lenalidomide and dexamethasone (IRD) versus lenalidomide and dexamethasone (RD) in patients with relapsed and refractory multiple myeloma (RRMM) in the routine clinical practice.

METHODS

A total of 344 patients treated with IRD (N = 127) or RD (N = 217) were selected for analysis from the Czech Registry of Monoclonal Gammopathies (RMG). Descriptive statistics were used to assess patient's characteristics associated with the respective therapy. The primary endpoint was progression free survival (PFS), secondary end points included response rates and overall survival (OS). Survival endpoints were plotted using Kaplan-Meier methodology at 95% Greenwood confidence interval. Univariable and multivariable Cox proportional hazards models were used to evaluate the effect of treatment regimens and the significance of uneven variables. Statistical tests were performed at significance level 0.05.

RESULTS

In the whole cohort, median PFS for IRD was 17.5 and for RD was 11.5 months favoring the all-oral triplet, p = 0.005; in patients within relapse 1-3, the median PFS was 23.1 vs 11.6 months, p = 0.001. The hazard ratio for PFS was 0.67 (95% confidence interval [CI] 0.51-0.89, p = 0.006). The PFS advantage translated into improved OS for patients treated with IRD, median 36.6 months vs 26.0 months (p = 0.008). The overall response rate (ORR) was 73.0% in the IRD group vs 66.2% in the RD group with a complete response rate (CR) of 11.1% vs 8.8%, and very good partial response (VGPR) 22.2% vs 13.9%, IRD vs RD respectively. The IRD regimen was most beneficial in patients ≤75 years with ISS I, II, and in the first and second relapse. Patients with the presence of extramedullary disease did not benefit from IRD treatment (median PFS 6.5 months). Both regimens were well tolerated, and the incidence of total as well as grade 3/4 toxicities was comparable.

CONCLUSIONS

Our analysis confirms the results of the TOURMALINE-MM1 study and shows benefit of all-oral triplet IRD treatment versus RD doublet. It demonstrates that the addition of ixazomib to RD improves key survival endpoints in patients with RRMM in a routine clinical setting.

Effect of Sepatronium Bromide (YM-155) on DNA Double-Strand Breaks Repair in Cancer Cells

Survivin, as an antiapoptotic protein often overexpressed in cancer cells, is a logical target for potential cancer treatment. By overexpressing survivin, cancer cells can avoid apoptotic cell death and often become resistant to treatments, representing a significant obstacle in modern oncology. A survivin suppressor, an imidazolium-based compound known as YM-155, is nowadays studied as an attractive anticancer agent. Although survivin suppression by YM-155 is evident, researchers started to report that YM-155 is also an inducer of DNA damage introducing yet another anticancer mechanism of this drug. Moreover, the concentrations of YM-155 for DNA damage induction seems to be far lower than those needed for survivin inhibition. Understanding the molecular mechanism of action of YM-155 is of vital importance for modern personalized medicine involving the selection of responsive patients and possible treatment combinations. This review focuses mainly on the documented effects of YM-155 on DNA damage signaling pathways. It summarizes up to date literature, and it outlines the molecular mechanism of YM-155 action in the context of the DNA damage field.

Abstract 5246: Disulfiram anticancer metabolite, dithiocarb-copper complex, demonstrates anti-neoplastic activity against hypermutated colorectal cancers

Introduction: Colorectal cancer (CRC) is the third leading cause of cancer related deaths in the United States. It was responsible for about 51,000 deaths during 2019. Surgical resection and systemic chemotherapy are standard approaches to treat both localized and metastatic CRC (mCRC). However, the effect of the chemotherapy depends on the characteristics of the individual tumor, for instance CRC subtypes with a microsatellite instability (MSI) tend to have better prognosis and response to both chemotherapy and immune check-point inhibition. Recently, Disulfiram's anti-cancer activity was explored and its metabolite ditiocarb-copper complex (CuET) was found to have high anti-cancer activity. The mechanism of action of CuET was proposed to act through p97 segregase adaptor NPL4 and activation of endoplasmic reticulum stress leading to preferential apoptosis of cancer cells. Since altered protein degradation pathway is targeted by CuET, this compound might display high efficacy in highly mutated colorectal cancers.

Methods: To assess CuET anti-cancer activity in vitro, we performed survival curve assays and colony-formation assays in both murine hypermutated colorectal cancer cell line MC-38 as well as in human KRAS mutant and MSI HCT116 cell line. We also evaluated anti-metastatic effect of CuET on both cell lines through migration-invasion assays in Boyden chamber setting. We assessed in vivo efficacy of systemic treatment with CuET alone or in combination with irinotecan, against MC-38 model in immunocompetent C57BL/6 mice. We characterized tumor growth, mice survival and tumor histopathology.

Results: Our results demonstrate that CuET displays cytotoxicity in MC-38 and HCT116 cells at very low doses with respective IC50 of 46nM and 88nM. CuET also significantly reduces the ability of both cell lines to grow and form colonies under sustained treatment. Additionally, CuET is effective in significantly reducing cancer cell migration and invasion through porous membrane in vitro. Furthermore, systemic treatment with CuET significantly reduced tumor growth in mice and prolonged survival when compared to controls.

Conclusion: CuET demonstrates cytotoxic activity against hypermutated colorectal cancer cells both in vitro and in vivo and should be further investigated in clinical trials.

Citation Format: Daciana Catalina Dumut, Juan B. De Sanctis, Martin Mistrik, Zdenek Skrott, Petr Dzubak, Jiri Bartek, Marian Hajduch, Danuta Radzioch. Disulfiram anticancer metabolite, dithiocarb-copper complex, demonstrates anti-neoplastic activity against hypermutated colorectal cancers [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5246.

Post-transplant cyclophosphamide versus antithymocyte globulin in patients with acute myeloid leukemia in first complete remission undergoing allogeneic stem cell transplantation from 10/10 HLA-matched unrelated donors

BACKGROUND

Graft-versus-host disease (GVHD) remains a major contributor to mortality and morbidity after allogeneic stem-cell transplantation (allo-HSCT). The updated recommendations suggest that rabbit antithymocyte globulin or anti-T-lymphocyte globulin (ATG) should be used for GVHD prophylaxis in patients undergoing matched-unrelated donor (MUD) allo-HSCT. More recently, using post-transplant cyclophosphamide (PTCY) in the haploidentical setting has resulted in low incidences of both acute (aGVHD) and chronic GVHD (cGVHD). Therefore, the aim of our study was to compare GVHD prophylaxis using either PTCY or ATG in patients with acute myeloid leukemia (AML) who underwent allo-HSCT in first remission (CR1) from a 10/10 HLA-MUD.

METHODS

Overall, 174 and 1452 patients from the EBMT registry receiving PTCY and ATG were included. Cumulative incidence of aGVHD and cGVHD, leukemia-free survival, overall survival, non-relapse mortality, cumulative incidence of relapse, and refined GVHD-free, relapse-free survival were compared between the 2 groups. Propensity score matching was also performed in order to confirm the results of the main analysis RESULTS: No statistical difference between the PTCY and ATG groups was observed for the incidence of grade II-IV aGVHD. The same held true for the incidence of cGVHD and for extensive cGVHD. In univariate and multivariate analyses, no statistical differences were observed for all other transplant outcomes. These results were also confirmed using matched-pair analysis.

CONCLUSION

These results highlight that, in the10/10 HLA-MUD setting, the use of PTCY for GVHD prophylaxis may provide similar outcomes to those obtained with ATG in patients with AML in CR1.

Impaired ribosome biogenesis: mechanisms and relevance to cancer and aging

The biosynthesis of ribosomes is a complex process that requires the coordinated action of many factors and a huge energy investment from the cell. Ribosomes are essential for protein production, and thus for cellular survival, growth and proliferation. Ribosome biogenesis is initiated in the nucleolus and includes: the synthesis and processing of ribosomal RNAs, assembly of ribosomal proteins, transport to the cytoplasm and association of ribosomal subunits. The disruption of ribosome biogenesis at various steps, with either increased or decreased expression of different ribosomal components, can promote cell cycle arrest, senescence or apoptosis. Additionally, interference with ribosomal biogenesis is often associated with cancer, aging and age-related degenerative diseases. Here, we review current knowledge on impaired ribosome biogenesis, discuss the main factors involved in stress responses under such circumstances and focus on examples with clinical relevance.

Targeting the NPL4 Adaptor of p97/VCP Segregase by Disulfiram as an Emerging Cancer Vulnerability Evokes Replication Stress and DNA Damage while Silencing the ATR Pathway

Research on repurposing the old alcohol-aversion drug disulfiram (DSF) for cancer treatment has identified inhibition of NPL4, an adaptor of the p97/VCP segregase essential for turnover of proteins involved in multiple pathways, as an unsuspected cancer cell vulnerability. While we reported that NPL4 is targeted by the anticancer metabolite of DSF, the bis-diethyldithiocarbamate-copper complex (CuET), the exact, apparently multifaceted mechanism(s) through which the CuET-induced aggregation of NPL4 kills cancer cells remains to be fully elucidated. Given the pronounced sensitivity to CuET in tumor cell lines lacking the genome integrity caretaker proteins BRCA1 and BRCA2, here we investigated the impact of NPL4 targeting by CuET on DNA replication dynamics and DNA damage response pathways in human cancer cell models. Our results show that CuET treatment interferes with DNA replication, slows down replication fork progression and causes accumulation of single-stranded DNA (ssDNA). Such a replication stress (RS) scenario is associated with DNA damage, preferentially in the S phase, and activates the homologous recombination (HR) DNA repair pathway. At the same time, we find that cellular responses to the CuET-triggered RS are seriously impaired due to concomitant malfunction of the ATRIP-ATR-CHK1 signaling pathway that reflects an unorthodox checkpoint silencing mode through ATR (Ataxia telangiectasia and Rad3 related) kinase sequestration within the CuET-evoked NPL4 protein aggregates.

The use of granulocyte colony stimulating factor after autologous hematopoietic stem cell transplantation

Restrospective study to evaluate the efficacy of early vs. delayed initiation of G-CSF after autologous hematopoietic stem cell transplantation (AHSCT) in patients with lymphoid malignancies.

BACKGROUND

Granulocyte colony stimulating factor (G-CSF) is commonly used after AHSCT to accelerate stem cell engraftment to minimize the morbidity and mortality associated with prolonged neutropenia. However, there is no consensus on the optimal timing of G-CSF after HSCT.

METHODS

A total of 117 patients with lymphoid malignancies who underwent AHSCT were included. All patients received G-CSF (filgrastim 5 μg/kg s.c.) daily after AHSCT (43 patients on day 6-8 and 74 patients on day 3 or 4). All patients received standard conditioning regimen for the underlying disease, and standard supportive treatment, including treatment of febrile neutropenia.

RESULTS

The incidence of severe neutropenia was 81 % vs 17 %, and very severe neutropenia 61 % vs 4 % in the delayed and early G-CSF groups, respectively (p < 0.0001). The rate of fungal infection was higher in the group of patients who received delayed G-CSF (p < 0.005).

CONCLUSION

An early administration of G-CSF after AHSCT (on day 3 or 4) accelerates neutophil engraftment; decreases the incidence of severe neutropenia and the risk of infectious complications (especially fungal infections) (Tab. 1, Fig. 3, Ref. 22).

Autologous hematopoietic stem cell transplantation for acute myeloid leukemia - single center experience

We aimed to determine the effect of autologous hematopoietic stem cell transplantation (auto-HSCT) on acute myeloid leukemia (AML) patients as a valid alternative therapeutic option for patients without HLA-compatible donor. This retrospective single center study included 79 patients with AML older than 18 years. In this report, we describe the patient characteristics, engraftment, toxicity of treatment, complications, overall survival, and relapse incidence of 79 patients treated chemotherapy and followed by auto-HSCT. The descriptive statistics was used, and the method of Kaplan and Meier was applied to calculate the actuarial rate of overall survival. The patients achieved an absolute neutrophile count (ANC) of ≥ 0.5 x109/l in between 10 to 40 days; median was 14 days after auto-HSCT. The patients achieved platelet count ≥ 20 x109/l in between 10 to 209 days; median was 19 days after auto-HSCT. Hundred-day mortality after autologous transplant was 6.57% (5/76). The relapse rate was 39.5% (32 patients) and 7 patients (8.6%) were lost from follow-up. On the date of evaluation (April 30, 2016), 48 patients (60.8%) were alive, including 7 (8.6%) patients who are lost from follow-up (not responding to check-up request). The 5-year overall survival (OS) was 60.8%; median overall survival was not reached. The present clinical study has demonstrated safety and efficacy of myeloablative chemotherapy followed by auto-HSCT in the treatment of AML in first remission.

PML nuclear bodies are recruited to persistent DNA damage lesions in an RNF168-53BP1 dependent manner and contribute to DNA repair

The bulk of DNA damage caused by ionizing radiation (IR) is generally repaired within hours, yet a subset of DNA lesions may persist even for long periods of time. Such persisting IR-induced foci (pIRIF) co-associate with PML nuclear bodies (PML-NBs) and are among the characteristics of cellular senescence. Here we addressed some fundamental questions concerning the nature and determinants of this co-association, the role of PML-NBs at such sites, and the reason for the persistence of DNA damage in human primary cells. We show that the persistent DNA lesions are devoid of homologous recombination (HR) proteins BRCA1 and Rad51. Our super-resolution microscopy-based analysis showed that PML-NBs are juxtaposed to and partially overlap with the pIRIFs. Notably, depletion of 53BP1 resulted in decreased intersection between PML-NBs and pIRIFs implicating the RNF168-53BP1 pathway in their interaction. To test whether the formation and persistence of IRIFs is PML-dependent and to investigate the role of PML in the context of DNA repair and senescence, we genetically deleted PML in human hTERT-RPE-1 cells. Unexpectedly, upon high-dose IR treatment, cells displayed similar DNA damage signalling, repair dynamics and kinetics of cellular senescence regardless of the presence or absence of PML. In contrast, the PML knock-out cells showed increased sensitivity to low doses of IR and DNA-damaging agents mitomycin C, cisplatin and camptothecin that all cause DNA lesions requiring repair by HR. These results, along with enhanced sensitivity of the PML knock-out cells to DNA-PK and PARP inhibitors implicate PML as a factor contributing to HR-mediated DNA repair.

Targeting genotoxic and proteotoxic stress-response pathways in human prostate cancer by clinically available PARP inhibitors, vorinostat and disulfiram

BACKGROUND

Castration-resistant prostate cancer (PCa) represents a serious health challenge. Based on mechanistically-supported rationale we explored new therapeutic options based on clinically available drugs with anticancer effects, including inhibitors of PARP1 enzyme (PARPi), and histone deacetylases (vorinostat), respectively, and disulfiram (DSF, known as alcohol-abuse drug Antabuse) and its copper-chelating metabolite CuET that inhibit protein turnover.

METHODS

Drugs and their combination with ionizing radiation (IR) were tested in various cytotoxicity assays in three human PCa cell lines including radio-resistant stem-cell like derived cells. Mechanistically, DNA damage repair, heat shock and unfolded protein response (UPR) pathways were assessed by immunofluorescence and immunoblotting.

RESULTS

We observed enhanced sensitivity to PARPi/IR in PC3 cells consistent with lower homologous recombination (HR) repair. Vorinostat sensitized DU145 cells to PARPi/IR and decreased mutant p53. Vorinostat also impaired HR-mediated DNA repair, as determined by Rad51 foci formation and downregulation of TOPBP1 protein, and overcame radio-resistance of stem-cell like DU145-derived cells. All PCa models responded well to CuET or DSF combined with copper. We demonstrated that DSF interacts with copper in the culture media and forms adequate levels of CuET indicating that DSF/copper and CuET may be considered as comparable treatments. Both DSF/copper and CuET evoked hallmarks of UPR in PCa cells, documented by upregulation of ATF4, CHOP and phospho-eIF2α, with ensuing heat shock response encompassing activation of HSF1 and HSP70. Further enhancing the cytotoxicity of CuET, combination with an inhibitor of the anti-apoptotic protein survivin (YM155, currently undergoing clinical trials) promoted the UPR-induced toxicity, yielding synergistic effects of CuET and YM155.

CONCLUSIONS

We propose that targeting genotoxic and proteotoxic stress responses by combinations of available drugs could inspire innovative strategies to treat castration-resistant PCa.

Senolytic Cocktail Dasatinib+Quercetin (D+Q) Does Not Enhance the Efficacy of Senescence-Inducing Chemotherapy in Liver Cancer

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death, which develops in the context of fibrosis and cirrhosis caused by chronic inflammation, in turn due to non-alcoholic fatty liver disease (NAFLD), alcohol consumption and/or hepatitis viral infection. An increased number of senescent cells are associated with age-related tissue degeneration during NAFLD-induced HCC, or during chemotherapeutic treatment. Senolytic agents target selectively senescent cells. A combination of the senolytic drugs dasatinib and quercetin (D+Q) reduced hepatic lipid accumulation and alleviated age-associated physical dysfunction in mice. However, whether D+Q can impact the treatment of HCC, at the end-stage of the NAFLD inflammatory spectrum, is unknown. Here, using two well-established HCC cell lines (HepG2, Huh-7), we demonstrate that the maximal cytostatic doses for D and/or Q (1 + 1 μM) lacked efficacy in removing doxorubicin-induced β-gal-positive senescent cells. Moreover, D+Q did not affect doxorubicin-dependent induction of flattened morphology, activation of p16, expression of SASP-associated genes or formation of γH2AX foci. We then investigated the antitumor efficacy of doxorubicin, D+Q, or the combination, in xenograft studies conducted with HCC cells inoculated in athymic nude mice. Doxorubicin reduced tumor growth by 30% compared to control mice, while D+Q was ineffective in synergizing with doxorubicin and in clearing doxorubicin-induced HCC senescent cells. Unexpectedly, D+Q alone appeared to have acute pro-tumorigenic effects in control mice. While our data need to be confirmed in animal models that fully recapitulate NAFLD, we demonstrate that these compounds are ineffective, alone or in synergy with senescence-inducing chemotherapy, against experimental HCC.

Abstract A006: Skp2 associates with Slug and androgen receptor in aggressive prostate cancer

Introduction: The Skp2 F-box protein is the substrate recruiting component of the SCF (Skp1-Cullin 1-F-box) type of E3 ubiquitin-ligase complexes. Skp2 plays an important role in prostate tumorigenesis (e.g., via recently reported stabilization of EZH2 or Twist1), which needs further elucidation.

Patients and Methods: Prostate cancer patient cohort (N=101) was analyzed by immunohistochemistry for the following proteins: Skp2, AR, Ki-67, Slug, E-cadherin, MdmX, Mdm2, and p53. The indicated proteins were also analyzed in seminal vesicles and lymph node metastases (SV=35 and LN=18 patients, respectively), as well as in benign prostatic hyperplasia (BPH=34). Colocalization analysis was performed using Perkin Elmer Opal Multiplex kit, Vectra 3.0 imaging system, and confocal microscope Carl Zeiss LSM 780. Independent prostate cancer cohort (N=30) was evaluated for TMPRSS2-ERG fusion by a triple-color deletion assay and assessed for Skp2, ERG, and NQO1 protein expression. Cox regression analysis and Kaplan-Meier curves were used to assess importance of Skp2, Slug, EZH2, and Twist1 for biochemical relapse in the TCGA prostate cancer dataset (N=488, RNA seq).

Results: Expression of E-cadherin was lower in primary prostate cancer and seminal vesicles compared to BPH and LN, which may be linked to epithelial-mesenchymal transition. Opposite expression profile was observed for Skp2, MdmX, and Slug. High Gleason score (≥8, N=30) was significantly associated with higher Skp2 and lower E-cadherin expression (p&lt;0.001 and 0.011, respectively). Skp2 slightly correlated with AR and Slug in the whole patient cohort (Rs 0.37 and 0.322, respectively). These correlations were stronger in patients with high Gleason score (Rs 0.53 and 0.56, respectively). In patients with metastasis into lymph nodes, Skp2 similarly correlated with Slug and AR (Rs 0.56 and 0.37, respectively) while androgen receptor further correlated with Ki-67 (Rs 0.50). Confocal microscopy revealed colocalization of Skp2 and Slug in prostate cancer cells. In an independent cohort, Skp2 correlated with expression of ERG, NQO1, and percentage of cancer cells positive for TMPRSS2-ERG (Rs 0.503, 0.387 and 0.615, respectively). In the TCGA dataset, high mRNA levels of Skp2 and EZH2 (but not Slug or Twist1) associated with shorter time to biochemical relapse, compared to low mRNA levels [HR 3.62 (2.1 – 6.23), p&lt;0.001].

Conclusion: Immunohistochemistry and colocalization studies revealed association between Skp2 and Slug in aggressive prostate cancer. Other factors such as TMPRSS2-ERG fusion or oxidative stress may contribute to prostate cancer progression.

Citation Format: Jan Bouchal, Gvantsa Kharaishvili, Alena Mickova, Mariam Gachechiladze, Alena Burdova, Martin Mistrik, Milan Kral, Balazs Gyorffy, Zdenek Kolar. Skp2 associates with Slug and androgen receptor in aggressive prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr A006.

Abstract 4166: Hair follicles as a minimally invasive resource of epithelial cells in mouse studies of ionizing radiation

Introduction

Hair follicles are relatively accessible as a biological material allowing repeatable and minimally invasive sampling of predominantly epithelial cells for biomarker studies. The utility of such a material is promising for example in murine experiments, where repeated sampling would require multiple biopsies.  As a proof of concept, the ionizing irradiation response in murine follicular cells was chosen as a suitable and common external factor for studying cellular senescence, apoptotic pathways, neoplastic transformation, tumor development and response to cancer therapy.     

Methods and material

Hair follicles were collected from 30 healthy C57Bl/6 mice into the RNA later for RT-qPCR and into the 4% formaldehyde for immunofluorescence with specially developed vacuum collector. Follicles were collected before X-ray irradiation and 30 min, 3 h, 6 h and 24 h after irradiation. Each group of 10 mice obtained one dose (2, 6 or 10 Gy). RNA was extracted from the samples using miRNeasy mini kit (Qiagen) and two-tube RT-qPCR was performed for SESN1, p21, MDM2 and HPRT gene expression analysis. Immunofluorescence was done for γ-H2AX and quantitatively evaluated by in-house developed software routine.   

Results 

Total RNA extracted from one pluck was usually less than 35 ng but it had good quality (RIN ≥ 7.5) even after the storage at room temperature. We determined p21 as the best marker for the uniformity and specific dynamic respond for each of the doses. The strongest responds were found after 30 min with 2 Gy (average fold change FCav = 3,24). In case of higher doses, longer remaining p21 overexpression was detected. For instance, FCav = 2,29 even after 24h at dose 10 Gy. Our data were corroborated by immunofluorescence for direct marker of ionizing radiation induced DNA damage γ-H2AX, where 1-3 hair follicles proved to be efficient for microscopic analyses. Strong γ-H2AX signal was detectable within 3h after irradiation followed by rapid decrease within the next 24h. 

Conclusion

Collected murine hair follicles proved to be a feasible alternative material for molecular analyses which in logistic aspects outreaches phlebotomies or skin biopsies because of repeatable, minimally invasive and accurate sampling and non-laborious processing. 

Dedication 

This work was financially supported by grants IGA_LF_2017_013, EATRIS-CZ, TACR TE02000058 and VG20102014001.

Citation Format: Hanus Slavik, Martin Mistrik, Pavlina Duskova, Tomas Furst, Josef Srovnal, Marian Hajduch. Hair follicles as a minimally invasive resource of epithelial cells in mouse studies of ionizing radiation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4166.

Abstract LB-264: Alcohol-aversion drug disulfiram targets cancer via p97 segregase adaptor NPL4

Cancer incidence is rising and this global challenge is further exacerbated by resistance of advanced tumors to standard-of-care and emerging precision medicines. A promising approach to such unmet need for innovative and cost-effective cancer treatments is drug repurposing, exploitation of drugs already approved for other indications that show anticancer activity. Here we highlight the potential for repurposing disulfiram (Antabuse), an old alcohol-aversion drug that kills a broad range of cancer types in preclinical studies. Our nationwide population study reveals that patients who continued using disulfiram have a lower risk of death from cancer compared to those who stopped using the drug at their diagnosis. More importantly, we identify ditiocarb-copper complex as the metabolite of disulfiram responsible for anticancer effects, present methods to detect its preferential accumulation in tumors and candidate biomarkers of impact in cells and tissues. Finally, our functional and biophysical analyses reveal the long-thought molecular target: NPL4 adapter of the p97/VCP segregase essential for protein recycling involved in multiple stress-response cellular pathways.

Citation Format: Martin Mistrik, Zdenek Skrott, Marian Hajduch, Søren Friis, Petr Dzubak, Jan Gursky, Dusana Majera, Tomas Ozdian, Jana Vaclavkova, Martina Michalova, Pavla Pouckova, Boris Cvek, Klaus Kaae Andersen, Jiři Bartek. Alcohol-aversion drug disulfiram targets cancer via p97 segregase adaptor NPL4 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-264.

Perturbation of RNA Polymerase I transcription machinery by ablation of HEATR1 triggers the RPL5/RPL11-MDM2-p53 ribosome biogenesis stress checkpoint pathway in human cells

Ribosome biogenesis is an energy consuming process which takes place mainly in the nucleolus. By producing ribosomes to fuel protein synthesis, it is tightly connected with cell growth and cell cycle control. Perturbation of ribosome biogenesis leads to the activation of p53 tumor suppressor protein promoting processes like cell cycle arrest, apoptosis or senescence. This ribosome biogenesis stress pathway activates p53 through sequestration of MDM2 by a subset of ribosomal proteins (RPs), thereby stabilizing p53. Here, we identify human HEATR1, as a nucleolar protein which positively regulates ribosomal RNA (rRNA) synthesis. Downregulation of HEATR1 resulted in cell cycle arrest in a manner dependent on p53. Moreover, depletion of HEATR1 also caused disruption of nucleolar structure and activated the ribosomal biogenesis stress pathway - RPL5 / RPL11 dependent stabilization and activation of p53. These findings reveal an important role for HEATR1 in ribosome biogenesis and further support the concept that perturbation of ribosome biosynthesis results in p53-dependent cell cycle checkpoint activation, with implications for human pathologies including cancer.

Alcohol-abuse drug disulfiram targets cancer via p97 segregase adaptor NPL4

Cancer incidence is rising and this global challenge is further exacerbated by tumour resistance to available medicines. A promising approach to such unmet need for improved cancer treatment is drug repurposing. Here we highlight the potential for repurposing disulfiram (Antabuse), an old alcohol-aversion drug effective against diverse cancer types in preclinical studies. Our nationwide epidemiological study reveals that patients who continuously used disulfiram have a lower risk of death from cancer compared to those who stopped using the drug at their diagnosis. Moreover, we identify ditiocarb-copper complex as the metabolite of disulfiram responsible for anticancer effects, and provide methods to detect its preferential accumulation in tumours and candidate biomarkers for impact in cells and tissues. Finally, our functional and biophysical analyses reveal the long-sought molecular target of disulfiram’s tumour suppressing effects as NPL4, an adapter of p97/VCP segregase essential for protein turnover involved in multiple regulatory and stress-response cellular pathways.

Improvement in asymmetric dimethylarginine and oxidative stress in patients with limb salvage after autologous mononuclear stem cell application for critical limb ischemia

Background

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, acts as an inhibitor of angiogenesis and is associated with an increased risk of cardiovascular mortality. Administration of stem cells may affect endogenous mechanisms that regulate ADMA production and metabolism. The aim of the present study was to analyze ADMA concentration and changes in oxidative stress in patients with advanced critical limb ischemia (CLI) after bone marrow-derived mononuclear cell (BM-MNC) therapy.

Methods

Fifty patients (age 64 ± 11 years, 44 males, 6 females) with advanced CLI (Rutherford category 5 or 6) not eligible for revascularization were treated by intramuscular (n = 25) or intra-arterial (n = 25) injection of 40 ml BM-MNC concentrate. Patients with limb salvage and improved wound healing after 6 months were considered responders to cell therapy. The concentrations of markers of oxidative stress and angiogenesis were analyzed before, and at 3 and 6 months after BM-MNC delivery.

Results

At 6-month follow-up, four patients died of reasons unrelated to stem cell therapy. Among the survivors, 80% (37/46) showed limb salvage and improved wound healing. At 6 months follow-up, ADMA concentration significantly decreased in patients with limb salvage (1.74 ± 0.66 to 0.90 ± 0.49 μmol/L, p < 0.001), in parallel with decreased tumor necrosis factor (TNF)-α (2.22 ± 0.16 to 1.94 ± 0.38 pg/ml, p < 0.001), and increased reduced glutathione (6.96 ± 3.1 to 8.67 ± 4.2 μmol/L, p = 0.02), superoxide dismutase activity (168 ± 50 to 218 ± 37 U/L, p = 0.002), and coenzyme Q10 concentration (468 ± 182 to 598 ± 283 μg/L, p = 0.02). The number of delivered BM-MNCs significantly correlated with the decrease in ADMA concentration at 3 months (p = 0.004, r = −0.48) and the decrease in TNF-α concentration at 6 months (p = 0.03, r = −0.44) after cell delivery. ADMA or TNF-α improvement did not correlate with the number of applied CD34⁺ cells, C-reactive protein concentration, leukocyte count, or the dose of atorvastatin.

Conclusions

The therapeutic benefit of BM-MNC therapy is associated with reduced ADMA levels and oxidative stress. Regulation of the ADMA-nitric oxide axis and improved antioxidant status may be involved in the beneficial effects of stem cell therapy.

Trial registration

The study was approved and retrospectively registered by ISRCTN registry, ISRCTN16096154. Registered on 26 July 2016.

Abstract 1413: Replication obstacles formed within common fragile sites under replication stress are targeted by the global genomic nucleotide excision repair pathway

CFS’s are genomic loci present in higher vertebrates that are particularly sensitive to various forms of replication stress and suffer from increased breakage and rearrangements in tumors. They have rather enigmatic evolutionary role and employ various DNA repair and checkpoint mechanisms promoting their stability. We used an original approach for identification of CFS’s associated factors based on DNA probe designed to match the high flexibility island sequences typically present in some of the highly expressed CFS’s. This probe was used as affinity bait for fishing specifically enriched proteins which were further identified using SILAC and quantitative mass spectrometry. Among already known CFS’s stabilizers we identified also hits so far not implicated in CFS’s maintenance. Interestingly, most of these novel hits are components of the global genomic nucleotide excision repair pathway (GG-NER). Knock down-based functional experiments revealed that GG-NER works most likely as an important trigger turning the CFS’s-associated replication obstacles into DNA lesion further recognized by the ATR-promoted cellular checkpoint which function is to block an escape of DNA replication intermediates into mitosis and the next cell generation. Work was supported by the Grant Agency of the Czech Republic 13-17555S, Czech-BioImaging project (LM2015062 funded by MEYS, CR) and Ministry of Education of the Czech Republic (LO1304).

Citation Format: Martin Mistrik, Lucie Beresova, Eva Vesela, Ivo Chamrad, Jiri Voller, Masayuki Yamada, Tomas Furst, Rene Lenobel, Katarina Chroma, Jan Gursky, Jiri Bartek. Replication obstacles formed within common fragile sites under replication stress are targeted by the global genomic nucleotide excision repair pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1413. doi:10.1158/1538-7445.AM2017-1413

Graft-versus-host disease management

Graft-versus-host disease (GVHD) remains a major problem of allogeneic hematopoietic-stem cell transplantation (HSCT) and an obstacle for successful outcome. Clinically significant acute GVHD (grade II or higher) developed in 20 to 65 percent of the patients. Death due to this complication accounts for approximately 50 percent of the deaths that are not due to a relapse of the neoplasm. Up to 70 % of patients who survive beyond day 100 develop chronic GVHD and it is the leading cause of nonrelapse mortality more than 2 years after allogeneic HSCT. In addition, chronic GVHD is associated with decreased quality of life, impaired functional status, and ongoing need for immunosuppressive medications. The incidence of chronic GVHD is increasing because of expansion of the donor population beyond HLA-identical siblings, older recipient age, use of peripheral blood cells as the graft source, and infusion of donor lymphocytes for treatment of recurrent malignancy after HSCT. With the current rush in new findings related to GVHD, we see a significant advancement in its management. Given these various new options and challenges, it is important to identify the minimal requirements for diagnosis and treatment of GVHD, as access to the most sophisticated advances may vary depending on local circumstances (Tab. 4, Fig. 1, Ref. 51).

Role of DNA Repair Factor Xeroderma Pigmentosum Protein Group C in Response to Replication Stress As Revealed by DNA Fragile Site Affinity Chromatography and Quantitative Proteomics

Replication stress (RS) fuels genomic instability and cancer development and may contribute to aging, raising the need to identify factors involved in cellular responses to such stress. Here, we present a strategy for identification of factors affecting the maintenance of common fragile sites (CFSs), which are genomic loci that are particularly sensitive to RS and suffer from increased breakage and rearrangements in tumors. A DNA probe designed to match the high flexibility island sequence typical for the commonly expressed CFS (FRA16D) was used as specific DNA affinity bait. Proteins significantly enriched at the FRA16D fragment under normal and replication stress conditions were identified using stable isotope labeling of amino acids in cell culture-based quantitative mass spectrometry. The identified proteins interacting with the FRA16D fragment included some known CFS stabilizers, thereby validating this screening approach. Among the hits from our screen so far not implicated in CFS maintenance, we chose Xeroderma pigmentosum protein group C (XPC) for further characterization. XPC is a key factor in the DNA repair pathway known as global genomic nucleotide excision repair (GG-NER), a mechanism whose several components were enriched at the FRA16D fragment in our screen. Functional experiments revealed defective checkpoint signaling and escape of DNA replication intermediates into mitosis and the next generation of XPC-depleted cells exposed to RS. Overall, our results provide insights into an unexpected biological role of XPC in response to replication stress and document the power of proteomics-based screening strategies to elucidate mechanisms of pathophysiological significance.

Characteristics of responders to autologous bone marrow cell therapy for no-option critical limb ischemia

BACKGROUND

The present study investigated factors associated with therapeutic benefits after autologous bone marrow cell (BMC) therapy in patients with "no-option" critical limb ischemia (CLI).

METHODS AND RESULTS

Sixty-two patients with advanced CLI (Rutherford category 5 or 6) not eligible for revascularization were randomized to treatment with 40 ml of autologous BMCs (SmartPreP2) by local intramuscular (n = 32) or intra-arterial (n = 30) application. The primary endpoint was limb salvage and wound healing at 12 months. Seven patients (11 %) died during the follow-up from reasons unrelated to stem cell therapy. The BMC product of patients with limb salvage and wound healing (33/55) was characterized by a higher CD34(+) cell count (p = 0.001), as well as a higher number of total bone marrow mononuclear cells (BM-MNCs) (p = 0.032), than that of nonresponders (22/55). Patients with limb salvage and wound healing were younger (p = 0.028), had lower C-reactive protein levels (p = 0.038), and had higher transcutaneous oxygen pressure (tcpO2) (p = 0.003) before cell application than nonresponders. All patients with major tissue loss at baseline (Rutherford 6 stage of CLI, n = 5) showed progression of limb ischemia and required major limb amputation. In the multiple binary logistic regression model, the number of applied CD34(+) cells (p = 0.046) and baseline tcpO2 (p = 0.031) were independent predictors of limb salvage and wound healing. The number of administrated BM-MNCs strongly correlated with decreased peripheral leukocyte count after 6 months in surviving patients with limb salvage (p = 0.0008).

CONCLUSION

Patients who benefited from autologous BMC therapy for "no-option" CLI were treated with high doses of CD34(+) cells. The absolute number of applied BM-MNCs correlated with the improvement of inflammation. We hypothesize that the therapeutic benefit of cell therapy for peripheral artery disease is the result of synergistic effects mediated by a mixture of active cells with regenerative potential. Patients at the most advanced stage of CLI do not appear to be suitable candidates for cell therapy.

TRIAL REGISTRATION

The study was approved and registered by the ISRCTN registry.

TRIAL REGISTRATION

ISRCTN16096154 . Registered: 26 July 2016.

Abstract 3598: Laser micro-irradiations of large amounts of cells for high content applications

A new methodical approach for the evaluation of photo-manipulated samples is presented and tested in various biological setups. The method is based on an atypical setting of a standard laser-scanning microscope (LSM) and image-processing software solution. Newly, a whole population of several dozen of cells is simultaneously micro-irradiated by a laser beam in a precisely defined pattern of collinear rays. Such laser induced striation pattern is automatically analyzed by specialized software routine providing quantitative assessment of various photo-manipulations, such as DNA-damage induced protein translocations or modifications, in both live and fixed cells. Automation of the process reduces workload and opens new possibilities for various dynamic studies and/or high content experiments. Results obtained during the testing of the method are presented and offer an insight into several DNA damage recognition and response pathways.

Citation Format: Martin Mistrik, Eva Vesela, Tomas Furst, Ivo Frydrych, Jan Gursky, Jiri Bartek. Laser micro-irradiations of large amounts of cells for high content applications. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3598.

Inhibitors in Severe Hemophilia A: 25-Year Experience in Slovakia

We present 25-year experience with inhibitors in previously untreated patients (PUPs) with severe hemophilia A in Slovakia, where safe factor VIII (FVIII) concentrates have been used since 1990. A prospective study focused on inhibitor incidence in PUPs was established in 1997. Out of a total 61 PUPs born between January 1997 and October 2015, 59 were eligible for evaluation; 50 and 9 were treated with > 20 exposure days (ED) of plasma-derived FVIII (pdFVIII) and recombinant FVIII (rFVIII) products, respectively. In the entire group 13/59 (22%) PUPs developed inhibitors; i.e. 7/50 (14%) and 6/9 (67%) treated with pdFVIII and rFVIII, respectively. Univariate analysis of inhibitor risk factors in patient groups with and without inhibitors showed the rFVIII and serious/recurrent infections within the first 50 EDs to be associated with inhibitor development (OR of 12.3 [95% CI 2.48–60.83; p = 0.002] and 5.0; [95% CI 1.16–21.9; p = 0.03), respectively]). Also, in multivariate Cox regression analysis, peak treatment ≥ 5 EDs reached statistical significance. The hazard ratio (HR) was 7.15 (95% CI 1.65–31.36) p = 0.0086 for rFVIII and 4.38 (95% CI 1.02–18.67) p = 0.046 for intensive treatment. Between 1993 and 2015, 21 immune tolerance inductions (ITIs) in 19 inhibitor patients were performed in the two largest hemophilia centers in Slovakia. In all but one ITI courses pdFVIII containing von Willebrand factor (FVIII/VWF) was used with preferred use of high-dose ITI (HD ITI) in high responders (HRs). Complete or partial success was achieved in 17/19 (89.5%) patients. Evaluating only the patients who already completed ITI, the success rate was even higher (15/16; 94%), including 7/7 low responders and 8/9 HR. Conclusion: Our national prospective study comprising entire group of PUPs with severe hemophilia A showed higher incidence of inhibitors in patients treated with rFVIII and those with intensive therapy within first 50 EDs. However, our experience is limited to small numbers of patients; thus, our results must be interpreted cautiously. High success rate of the ITI in our inhibitor patients has been achieved with FVIII/VWF concentrates and preferred use of HD ITI in HR patients.

DNA damage signalling barrier, oxidative stress and treatment-relevant DNA repair factor alterations during progression of human prostate cancer

The DNA damage checkpoints provide an anti-cancer barrier in diverse tumour types, however this concept has remained unexplored in prostate cancer (CaP). Furthermore, targeting DNA repair defects by PARP1 inhibitors (PARPi) as a cancer treatment strategy is emerging yet requires suitable predictive biomarkers. To address these issues, we performed immunohistochemical analysis of multiple markers of DNA damage signalling, oxidative stress, DNA repair and cell cycle control pathways during progression of human prostate disease from benign hyperplasia, through intraepithelial neoplasia to CaP, complemented by genetic analyses of TMPRSS2-ERG rearrangement and NQO1, an anti-oxidant factor and p53 protector. The DNA damage checkpoint barrier (γH2AX, pATM, p53) mechanism was activated during CaP tumorigenesis, albeit less and with delayed culmination compared to other cancers, possibly reflecting lower replication stress (slow proliferation despite cases of Rb loss and cyclin D1 overexpression) and progressive loss of ATM activator NKX3.1. Oxidative stress (8-oxoguanine lesions) and NQO1 increased during disease progression. NQO1 genotypes of 390 men did not indicate predisposition to CaP, yet loss of NQO1 in CaP suggested potential progression-opposing tumour suppressor role. TMPRSS2-ERG rearrangement and PTEN loss, events sensitizing to PARPi, occurred frequently along with heterogeneous loss of DNA repair factors 53BP1, JMJD1C and Rev7 (all studied here for the first time in CaP) whose defects may cause resistance to PARPi. Overall, our results reveal an unorthodox DNA damage checkpoint barrier scenario in CaP tumorigenesis, and provide novel insights into oxidative stress and DNA repair, with implications for biomarker guidance of future targeted therapy of CaP.

Cells and Stripes: A novel quantitative photo-manipulation technique

Laser micro-irradiation is a technology widely used in the DNA damage response, checkpoint signaling, chromatin remodeling and related research fields, to assess chromatin modifications and recruitment of diverse DNA damage sensors, mediators and repair proteins to sites of DNA lesions. While this approach has aided numerous discoveries related to cell biology, maintenance of genome integrity, aging and cancer, it has so far been limited by a tedious manual definition of laser-irradiated subcellular regions, with the ensuing restriction to only a small number of cells treated and analyzed in a single experiment. Here, we present an improved and versatile alternative to the micro-irradiation approach: Quantitative analysis of photo-manipulated samples using innovative settings of standard laser-scanning microscopes. Up to 200 cells are simultaneously exposed to a laser beam in a defined pattern of collinear rays. The induced striation pattern is then automatically evaluated by a simple algorithm, which provides a quantitative assessment of various laser-induced phenotypes in live or fixed cells. Overall, this new approach represents a more robust alternative to existing techniques, and provides a versatile tool for a wide range of applications in biomedicine.

Synthesis and study of novel pH-independent fluorescent mitochondrial labels based on Rhodamine B

Several Rhodamine B derivatives based on a tri-substituted pyrimidine core were prepared using solid-phase chemistry. Some derivatives exhibited fluorescence also at high pH and showed significant mitochondrial localization.

Genetic and biochemical study of dual hereditary jaundice: Dubin-Johnson and Gilbert's syndromes. Haplotyping and founder effect of deletion in ABCC2

Dual hereditary jaundice, a combination of Dubin-Johnson and Gilbert's syndromes, is a rare clinical entity resulting from the compound defects of bilirubin conjugation and transport. We aimed to study the hereditary jaundice in 56 members from seven seemingly unrelated Roma families, to find the causal genetic defect and to estimate its origin in Roma population. On the basis of biochemical results of total and conjugated serum bilirubin and clinical observations, ABCC2 gene, TATA box and phenobarbital enhancer (PBREM) of UGT1A1 gene were analyzed by sequencing, RFLP and fragment analysis. We found a novel variant c.1013_1014delTG in the eighth exon of ABCC2 gene in 17 individuals in homozygous state. Dual defect NG_011798.1:c.[1013_1014delTG]; NG_002601.2:g.[175492_175493insTA] in homozygous state was found in four subjects. Biochemical analyses of porphyrins and coproporphyrin isomers in urine performed by HPLC showed inverted ratio of excreted coproporphyrin, with the predominance of coproporphyrin I (up to 100%), typical for patients with Dubin-Johnson syndrome. Pursuant cultural and social specifics of the population led us to suspect a founder effect; therefore, we performed a haplotype study using genotyping data from Affymetrix Genome-Wide Human SNP Array 6.0. As a result, we detected a common 86 kbp haplotype encompassing promoter and part of the ABCC2 coding region among all families, and estimated the age of the ancestral variant to 178-185 years. In this study, we found a novel deletion in ABCC2 gene, described genetic and biochemical features of dual hereditary jaundice and confirmed the existence of founder effect and common haplotype among seven Roma families.

REV7 counteracts DNA double-strand break resection and affects PARP inhibition

Error-free repair of DNA double-strand breaks (DSBs) is achieved by homologous recombination (HR), and BRCA1 is an important factor for this repair pathway. In the absence of BRCA1-mediated HR, the administration of PARP inhibitors induces synthetic lethality of tumour cells of patients with breast or ovarian cancers. Despite the benefit of this tailored therapy, drug resistance can occur by HR restoration. Genetic reversion of BRCA1-inactivating mutations can be the underlying mechanism of drug resistance, but this does not explain resistance in all cases. In particular, little is known about BRCA1-independent restoration of HR. Here we show that loss of REV7 (also known as MAD2L2) in mouse and human cell lines re-establishes CTIP-dependent end resection of DSBs in BRCA1-deficient cells, leading to HR restoration and PARP inhibitor resistance, which is reversed by ATM kinase inhibition. REV7 is recruited to DSBs in a manner dependent on the H2AX-MDC1-RNF8-RNF168-53BP1 chromatin pathway, and seems to block HR and promote end joining in addition to its regulatory role in DNA damage tolerance. Finally, we establish that REV7 blocks DSB resection to promote non-homologous end-joining during immunoglobulin class switch recombination. Our results reveal an unexpected crucial function of REV7 downstream of 53BP1 in coordinating pathological DSB repair pathway choices in BRCA1-deficient cells.