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.
- MeSH
- dánio pruhované metabolismus MeSH
- disulfiram * metabolismus MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- nádorový supresorový protein p53 genetika metabolismus MeSH
- nádory * metabolismus MeSH
- ribozomy metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
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.
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.
- MeSH
- antitumorózní látky * farmakologie terapeutické užití MeSH
- Cannabis * MeSH
- kanabidiol * farmakologie terapeutické užití MeSH
- kanabinoidy * terapeutické užití MeSH
- lékové interakce MeSH
- lidé MeSH
- nádory * farmakoterapie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
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.
- MeSH
- anxiolytika * farmakologie MeSH
- Caenorhabditis elegans MeSH
- léky proti stárnutí * MeSH
- lidé MeSH
- ligandy MeSH
- myši MeSH
- narkotika - antagonisté farmakologie MeSH
- opioidní analgetika MeSH
- opioidní peptidy MeSH
- piperidiny farmakologie MeSH
- receptory opiátové MeSH
- rychlé screeningové testy MeSH
- stárnutí buněk * MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
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.
Ribosome biogenesis is an essential, energy demanding process whose deregulation has been implicated in cancer, aging, and neurodegeneration. Ribosome biogenesis is therefore under surveillance of pathways including the p53 tumor suppressor. Here, we first performed a high-content siRNA-based screen of 175 human ribosome biogenesis factors, searching for impact on p53. Knock-down of 4 and 35 of these proteins in U2OS cells reduced and increased p53 abundance, respectively, including p53 accumulation after depletion of BYSL, DDX56, and WDR75, the effects of which were validated in several models. Using complementary approaches including subcellular fractionation, we demonstrate that endogenous human WDR75 is a nucleolar protein and immunofluorescence analysis of ectopic GFP-tagged WDR75 shows relocation to nucleolar caps under chemically induced nucleolar stress, along with several canonical nucleolar proteins. Mechanistically, we show that WDR75 is required for pre-rRNA transcription, through supporting the maintenance of physiological levels of RPA194, a key subunit of the RNA polymerase I. Furthermore, WDR75 depletion activated the RPL5/RPL11-dependent p53 stabilization checkpoint, ultimately leading to impaired proliferation and cellular senescence. These findings reveal a crucial positive role of WDR75 in ribosome biogenesis and provide a resource of human ribosomal factors the malfunction of which affects p53.
- MeSH
- buněčné jadérko genetika metabolismus MeSH
- DEAD-box RNA-helikasy metabolismus MeSH
- jaderné proteiny genetika metabolismus MeSH
- lidé MeSH
- molekuly buněčné adheze metabolismus MeSH
- nádorové buněčné linie MeSH
- nádorový supresorový protein p53 genetika metabolismus MeSH
- prekurzory RNA metabolismus MeSH
- ribozomální proteiny * genetika metabolismus MeSH
- ribozomy genetika metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Accumulation of senescent cells in tissues with advancing age participates in the pathogenesis of several human age-associated diseases. Specific senescent secretome, the resistance of senescent cells to apoptotic stimuli, and lack of immune system response contribute to the accumulation of senescent cells and their adverse effects in tissues. Inhibition of antiapoptotic machinery, augmented in senescent cells, by BCL-2 protein family inhibitors represents a promising approach to eliminate senescent cells from tissues. This study aimed to explore synergistic and selective senolytic effects of anti-apoptotic BCL-2 family targeting compounds, particularly BH3 mimetics. Using human non-transformed cells RPE-1, BJ, and MRC-5 brought to ionizing radiation-, oncogene-, drug-induced and replicative senescence, we found synergy in combining MCL-1 selective inhibitors with other BH3 mimetics. In an attempt to uncover the mechanism of such synergy, we revealed that the surviving subpopulation of cells resistant to individually applied ABT-737/ABT-263, MIK665, ABT-199, and S63845 BCL-2 family inhibitors showed elevated MCL-1 compared to untreated control cells indicating the presence of a subset of cells expressing high MCL-1 levels and, therefore, resistant to BCL-2 inhibitors within the original population of senescent cells. Overall, we found that combining BCL-2 inhibitors can be beneficial for eliminating senescent cells, thereby enabling use of lower, potentially less toxic, doses of drugs compared to monotherapy, thereby overcoming the resistance of the subpopulation of senescent cells to monotherapy.
- MeSH
- apoptóza MeSH
- lidé MeSH
- protein MCL-1 metabolismus MeSH
- protoonkogenní proteiny c-bcl-2 * antagonisté a inhibitory MeSH
- stárnutí buněk * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Genotoxic therapy such as radiation serves as a frontline cancer treatment, yet acquired resistance that leads to tumor reoccurrence is frequent. We found that cancer cells maintain viability during irradiation by reversibly increasing genome-wide DNA breaks, thereby limiting premature mitotic progression. We identify caspase-activated DNase (CAD) as the nuclease inflicting these de novo DNA lesions at defined loci, which are in proximity to chromatin-modifying CCCTC-binding factor (CTCF) sites. CAD nuclease activity is governed through phosphorylation by DNA damage response kinases, independent of caspase activity. In turn, loss of CAD activity impairs cell fate decisions, rendering cancer cells vulnerable to radiation-induced DNA double-strand breaks. Our observations highlight a cancer-selective survival adaptation, whereby tumor cells deploy regulated DNA breaks to delimit the detrimental effects of therapy-evoked DNA damage.
Up to 15% of human cancers maintain their telomeres through a telomerase-independent mechanism, termed "alternative lengthening of telomeres" (ALT) that relies on homologous recombination between telomeric sequences. Emerging evidence suggests that the recombinogenic nature of ALT telomeres results from the formation of RNA:DNA hybrids (R-loops) between telomeric DNA and the long-noncoding telomeric repeat-containing RNA (TERRA). Here, we show that the mismatch repair protein MutSβ, a heterodimer of MSH2 and MSH3 subunits, is enriched at telomeres in ALT cancer cells, where it prevents the accumulation of telomeric G-quadruplex (G4) structures and R-loops. Cells depleted of MSH3 display increased incidence of R-loop-dependent telomere fragility and accumulation of telomeric C-circles. We also demonstrate that purified MutSβ recognizes and destabilizes G4 structures in vitro. These data suggest that MutSβ destabilizes G4 structures in ALT telomeres to regulate TERRA R-loops, which is a prerequisite for maintenance of telomere integrity during ALT.
- MeSH
- DNA metabolismus MeSH
- homeostáza telomer MeSH
- lidé MeSH
- nádory * genetika MeSH
- R-smyčka MeSH
- RNA dlouhá nekódující * metabolismus MeSH
- telomery metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Repetitive sequences are among the most unstable regions in the eukaryotic genome and defects in their maintenance correlate with premature aging and cancer development. Promyelocytic leukemia protein (PML) induces accumulation of proteins at distinct nuclear sites, thereby affecting a plethora of processes including DNA repair or maintenance of telomeres. Doxorubicin, the broadly used chemotherapeutic compound, induces formation of PML-nucleolar associations (PNAs). Nevertheless, molecular factors affecting formation of PNAs are still largely unknown. Here we show that PNAs can accumulate ribosomal DNA (rDNA) and, after restoration of RNA polymerase I activity, these structures transfer a fraction of rDNA outside the nucleolus. Mutagenesis of PML isoforms revealed that this process depends on the SUMO-interacting motif and adjacent serine-rich region, and is enhanced by exon8b present exclusively in PML IV isoform. Moreover, we demonstrate that PNAs formation is also regulated by p14ARF/p53 tumor suppressors and casein kinase 2. Our data elucidate how PML nucleolar compartment is assembled, bring the first evidence of PML interacting with rDNA, and show the PML-dependent translocation of rDNA away from the nucleolus.
