| 1. |
- Aftab, Obaid, 1984-, et al.
(författare)
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Label-free detection and dynamic monitoring of drug-induced intracellular vesicle formation enabled using a 2-dimensional matched filter
- 2014
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8627 .- 1554-8635. ; 10:1, s. 57-69
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Tidskriftsartikel (refereegranskat)abstract
- Analysis of vesicle formation and degradation is a central issue in autophagy research and microscopy imaging is revolutionizing the study of such dynamic events inside living cells. A limiting factor is the need for labeling techniques that are labor intensive, expensive, and not always completely reliable. To enable label-free analyses we introduced a generic computational algorithm, the label-free vesicle detector (LFVD), which relies on a matched filter designed to identify circular vesicles within cells using only phase-contrast microscopy images. First, the usefulness of the LFVD is illustrated by presenting successful detections of autophagy modulating drugs found by analyzing the human colorectal carcinoma cell line HCT116 exposed to each substance among 1266 pharmacologically active compounds. Some top hits were characterized with respect to their activity as autophagy modulators using independent in vitro labeling of acidic organelles, detection of LC3-II protein, and analysis of the autophagic flux. Selected detection results for 2 additional cell lines (DLD1 and RKO) demonstrate the generality of the method. In a second experiment, label-free monitoring of dose-dependent vesicle formation kinetics is demonstrated by recorded detection of vesicles over time at different drug concentrations. In conclusion, label-free detection and dynamic monitoring of vesicle formation during autophagy is enabled using the LFVD approach introduced.
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| 2. |
- Brnjic, Slavica, et al.
(författare)
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Induction of Tumor Cell Apoptosis by a Proteasome Deubiquitinase Inhibitor Is Associated with Oxidative Stress
- 2014
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Ingår i: Antioxidants and Redox Signaling. - : Mary Ann Liebert Inc. - 1523-0864 .- 1557-7716. ; 21:17, s. 2271-2285
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Tidskriftsartikel (refereegranskat)abstract
- Aims: b-AP15 is a recently described inhibitor of the USP14/UCHL5 deubiquitinases (DUBs) of the 19S proteasome. Exposure to b-AP15 results in blocking of proteasome function and accumulation of polyubiquitinated protein substrates in cells. This novel mechanism of proteasome inhibition may potentially be exploited for cancer therapy, in particular for treatment of malignancies resistant to currently used proteasome inhibitors. The aim of the present study was to characterize the cellular response to b-AP15-mediated proteasome DUB inhibition. Results: We report that b-AP15 elicits a similar, but yet distinct, cellular response as the clinically used proteasome inhibitor bortezomib. b-AP15 induces a rapid apoptotic response, associated with enhanced induction of oxidative stress and rapid activation of Jun-N-terminal kinase 1/2 (JNK)/activating protein-1 signaling. Scavenging of reactive oxygen species and pharmacological inhibition of JNK reduced b-AP15-induced apoptosis. We further report that endoplasmic reticulum (ER) stress is induced by b-AP15 and is involved in apoptosis induction. In contrast to bortezomib, ER stress is associated with induction of alpha-subunit of eukaryotic initiation factor 2 phosphorylation. Innovation: The findings establish that different modes of proteasome inhibition result in distinct cellular responses, a finding of potential therapeutic importance. Conclusion: Our data show that enhanced oxidative stress and ER stress are major determinants of the strong apoptotic response elicited by the 19S DUB inhibitor b-AP15. Antioxid. Redox Signal. 21, 2271-2285.
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| 3. |
- D'Arcy, Pádraig, et al.
(författare)
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Inhibition of proteasome deubiquitinating activity as a novel cancer therapy
- 2011
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Ingår i: Nature Medicine. - Stockholm : Karolinska Institutet, Dept of Oncology-Pathology. - 1546-170X .- 1078-8956.
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Tidskriftsartikel (refereegranskat)abstract
- Ubiquitin-tagged substrates are degraded by the 26S proteasome, which is a multisubunit complex comprising a proteolytic 20S core particle capped by 19S regulatory particles. The approval of bortezomib for the treatment of multiple myeloma validated the 20S core particle as an anticancer drug target. Here we describe the small molecule b-AP15 as a previously unidentified class of proteasome inhibitor that abrogates the deubiquitinating activity of the 19S regulatory particle. b-AP15 inhibited the activity of two 19S regulatory-particle-associated deubiquitinases, ubiquitin C-terminal hydrolase 5 (UCHL5) and ubiquitin-specific peptidase 14 (USP14), resulting in accumulation of polyubiquitin. b-AP15 induced tumor cell apoptosis that was insensitive to TP53 status and overexpression of the apoptosis inhibitor BCL2. We show that treatment with b-AP15 inhibited tumor progression in four different in vivo solid tumor models and inhibited organ infiltration in an acute myeloid leukemia model. Our results show that the deubiquitinating activity of the 19S regulatory particle is a new anticancer drug target.
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| 4. |
- D'Arcy, Padraig, et al.
(författare)
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Molecular Pathways : Translational Potential of Deubiquitinases as Drug Targets
- 2014
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Ingår i: Clinical Cancer Research. - 1078-0432 .- 1557-3265. ; 20:15, s. 3908-3914
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Tidskriftsartikel (refereegranskat)abstract
- The ubiquitin proteasome system (UPS) is the main system for controlled protein degradation and a key regulator of fundamental cellular processes. The dependency of cancer cells on a functioning UPS coupled with the clinical success of bortezomib for the treatment of multiple myeloma have made the UPS an obvious target for drug development. Deubiquitinases (DUB) are components of the UPS that encompass a diverse family of ubiquitin isopeptidases that catalyze the removal of ubiquitin moieties from target proteins or from polyubiquitin chains, resulting in altered signaling or changes in protein stability. Increasing evidence has implicated deregulation of DUB activity in the initiation and progression of cancer. The altered pattern of DUB expression observed in many tumors can potentially serve as a clinical marker for predicting disease outcome and therapy response. The finding of DUB overexpression in tumor cells suggests that they may serve as novel targets for the development of anticancer therapies. Several specific and broad-spectrum DUB inhibitors are shown to have antitumor activity in preclinical in vivo models with low levels of systemic toxicity. Future studies will hopefully establish the clinical potential for DUB inhibitors as a strategy to treat cancer.
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| 5. |
- De Petris, Luigi, et al.
(författare)
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Diagnostic and prognostic role of plasma levels of two forms of cytokeratin 18 in patients with non-small-cell lung cancer
- 2011
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Ingår i: European Journal of Cancer. - : Elsevier BV. - 0959-8049 .- 1879-0852. ; 47:1, s. 131-137
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE:Cytokeratin 18 (CK18) can be used as a serum biomarker for carcinoma cell death, whereas caspase-cleaved (ccCK18) fragments reflect tumour apoptosis. We explored the potential diagnostic and prognostic role of circulating CK18 and ccCK18 in patients with non-small-cell lung cancer (NSCLC) in comparison with Cyfra 21.1, a fragment of cytokeratin 19.METHODS:Subject cohorts consisted of 200 healthy blood donors (HBD), 113 patients with benign lung diseases (BLD) and 179 NSCLC cases. Plasma levels of ccCK18, total CK18 and Cyfra 21.1 were determined with ELISA assays.RESULTS:Plasma levels of ccCK18 and total CK18 were higher in the NSCLC group compared to the HBD and BLD cohorts (p<0.0001). Using a cut-off of 104 U/L for ccCK18 and 302 U/L for total CK18 (95% specificity in the HBD group) the diagnostic accuracy of both CK18 forms to distinguish between NSCLC and BLD cases was 56%, whereas it was 94% for Cyfra 21.1. Multivariate survival analysis showed that total CK18 was a stronger prognostic factor than both ccCK18 and Cyfra 21.1 (HR 0.64 for low versus high total CK18 levels, 95% confidence interval (CI) 0.50-0.82; p=0.0004) in the entire NSCLC cohort and in 78 patients with locally advanced or metastatic disease treated with chemoradiotherapy or first-line chemotherapy (HR 0.70 95% CI 0.52-0.94; p=0.018).CONCLUSIONS:Cyfra 21.1 is a useful diagnostic biomarker for NSCLC. Total CK18 shows a promising potential as prognostic marker in NSCLC patients, independently of the therapeutical intervention. In contrast, ccCK18 was not of prognostic value in NSCLC, suggesting that tumour necrosis is of particular importance in this disease.
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| 6. |
- Fayad, Walid, et al.
(författare)
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Identification of Agents that Induce Apoptosis of Multicellular Tumour Spheroids : Enrichment for Mitotic Inhibitors with Hydrophobic Properties
- 2011
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Ingår i: Chemical Biology and Drug Design. - : Wiley. - 1747-0277 .- 1747-0285. ; 78:4, s. 547-557
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Tidskriftsartikel (refereegranskat)abstract
- Cell-based anticancer drug screening generally utilizes rapidly proliferating tumour cells grown as monolayer cultures. Hit compounds from such screens are not necessarily effective on hypoxic and slowly proliferating cells in 3-D tumour tissue. The aim of this study was to examine the potential usefulness of 3-D cultured tumour cells for anticancer drug screening. We used colon carcinoma multicellular spheroids containing hypoxic and quiescent cells in core areas for this purpose. Three libraries (similar to 11 000 compounds) were screened using antiproliferative activity and/or apoptosis as end-points. Screening of monolayer and spheroid cultures was found to identify different sets of hit compounds. Spheroid screening enriched for hydrophobic compounds: median XLogP values of 4.3 and 4.4 were observed for the hits in two independent screening campaigns. Mechanistic analysis revealed that the majority of spheroid screening hits were microtubuli inhibitors. One of these inhibitors was examined in detail and found to be effective against non-dividing cells in the hypoxic centres of spheroids. Spheroid screening represents a conceptually new strategy for anticancer drug discovery. Our findings have implications for drug library design and hit selection in projects aimed to develop drugs for the treatment of solid tumours.
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| 7. |
- Felth, Jenny, 1979-, et al.
(författare)
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Gambogic acid is cytotoxic to cancer cells through inhibition of the ubiquitin-proteasome system
- 2013
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Ingår i: Investigational new drugs. - : Springer Science and Business Media LLC. - 0167-6997 .- 1573-0646. ; 31:3, s. 587-598
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Gambogic acid (GA), displays cytotoxicity towards a wide variety of tumor cells and has been shown to affect many important cell-signaling pathways. In the present work, we investigated the mechanism of action of GA by analysis of drug-induced changes in gene expression profiles and identified GA and the derivative dihydro GA as possible inhibitors of the ubiquitin-proteasome system (UPS). Both GA and dihydro GA inhibited proteasome function in cells resulting in the accumulation of polyubiquitin complexes. In vitro experiments showed that both GA and dihydro GA inhibited 20S chymotrypsin activity and the inhibitory effects of GA and dihydro GA on proteasome function corresponded with apoptosis induction and cell death. In conclusion, our results show that GA and dihydro GA exert their cytotoxic activity through inhibition of the UPS, specifically by acting as inhibitors of the chymotrypsin activity of the 20S proteasome.
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| 8. |
- Fryknäs, Mårten, et al.
(författare)
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Screening for phenotype selective activity in multidrug resistant cells identifies a novel tubulin active agent insensitive to common forms of cancer drug resistance
- 2013
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Ingår i: BMC Cancer. - : Springer Science and Business Media LLC. - 1471-2407 .- 1471-2407. ; 13, s. 374-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Drug resistance is a common cause of treatment failure in cancer patients and encompasses a multitude of different mechanisms. The aim of the present study was to identify drugs effective on multidrug resistant cells. Methods: The RPMI 8226 myeloma cell line and its multidrug resistant subline 8226/Dox40 was screened for cytotoxicity in response to 3,000 chemically diverse compounds using a fluorometric cytotoxicity assay (FMCA). Follow-up profiling was subsequently performed using various cellular and biochemical assays. Results: One compound, designated VLX40, demonstrated a higher activity against 8226/Dox40 cells compared to its parental counterpart. VLX40 induced delayed cell death with apoptotic features. Mechanistic exploration was performed using gene expression analysis of drug exposed tumor cells to generate a drug-specific signature. Strong connections to tubulin inhibitors and microtubule cytoskeleton were retrieved. The mechanistic hypothesis of VLX40 acting as a tubulin inhibitor was confirmed by direct measurements of interaction with tubulin polymerization using a biochemical assay and supported by demonstration of G2/M cell cycle arrest. When tested against a broad panel of primary cultures of patient tumor cells (PCPTC) representing different forms of leukemia and solid tumors, VLX40 displayed high activity against both myeloid and lymphoid leukemias in contrast to the reference compound vincristine to which myeloid blast cells are often insensitive. Significant in vivo activity was confirmed in myeloid U-937 cells implanted subcutaneously in mice using the hollow fiber model. Conclusions: The results indicate that VLX40 may be a useful prototype for development of novel tubulin active agents that are insensitive to common mechanisms of cancer drug resistance.
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| 9. |
- Haglund, Caroline, et al.
(författare)
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Identification of an inhibitor of the ubiquitin-proteasome system that induces accumulation of polyubiquitinated proteins in the absence of blocking of proteasome function
- 2014
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Ingår i: MedChemComm. - : Royal Society of Chemistry (RSC). - 2040-2503 .- 2040-2511. ; 5:3, s. 376-385
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Tidskriftsartikel (refereegranskat)abstract
- The ubiquitin-proteasome system (UPS) represents one of the most promising therapeutic targets in oncology to emerge in recent years. Here we used a combination of cytotoxic and image-based screening assays to identify a novel UPS inhibitor, designated HRF-3. HRF-3 evokes a gene expression profile similar to that of other characterized ups inhibitors, suggesting a common mechanism of action. Consistent with UPS inhibition, HRF-3 induced strong accumulation of polyubiquitinated proteins in cells. Surprisingly, HRF-3 induced only weak accumulation of two proteasome targeted reporter proteins, Ub(G76V)-YFP and ZsGreen-ODC. Consistent with this observation, HRF-3 did not inhibit proteasome proteolytic activity in an in vitro assay. Similar to a number of other UPS inhibitors, HRF-3 increased the expression of the redox-inducible protein Hmox-1. In distinction to the 20S inhibitor bortezomib, but similarly to two different p97/VCP inhibitors. HRF-3 did not elicit strong induction of the chaperone Hsp70B'. Finally, we show that HRF-3 is cytotoxic to a variety of cancer cell lines and ex vivo patient tumour cells, with the strongest activity observed in cells of leukemic/myeloma origin. Taken together our data show that HRF-3 induces polyubiquitin accumulation in the absence of efficient proteasomal blocking, and suggest that induction of oxidative stress is a common denominator of UPS inhibitors.
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| 10. |
- Hassan, Saadia, et al.
(författare)
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Novel activity of acriflavine against colorectal cancer tumor cells
- 2011
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Ingår i: Cancer Science. - : Wiley. - 1347-9032 .- 1349-7006. ; 102:12, s. 2206-2213
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Tidskriftsartikel (refereegranskat)abstract
- A high-throughput screen of the cytotoxic activity of 2000 molecules from a commercial library in three human colon cancer cell lines and two normal cell types identified the acridine acriflavin to be a colorectal cancer (CRC) active drug. Acriflavine was active in cell spheroids, indicating good drug penetration and activity against hypoxic cells. In a validation step based on primary cultures of patient tumor cells, acriflavine was found to be more active against CRC than ovarian cancer and chronic lymphocytic leukemia. This contrasted to the activity pattern of the CRC active standard drugs 5-fluorouracil, irinotecan and oxaliplatin. Mechanistic studies indicated acriflavine to be a dual topoisomerase I and II inhibitor. In conclusion, the strategy used seems promising for identification of new diagnosis-specific cancer drugs.
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