| 1. |
- 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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| 2. |
- Mohanty, Chitralekha
(författare)
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Different approaches to develop radio- and chemotherapy for treatment of human cancer
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Despite huge advancements in our knowledge and understanding of the molecular mechanisms of carcinogenesis, the prognoses of many malignant diseases have not improved dramatically. Improvements in the therapeutic efficacy of several anti-cancer therapies including radiotherapy and chemotherapy would be required to achieve effective treatment. In the present thesis we attempt to improve radiotherapy by proposing new molecular targets for overcoming radio-resistance and identify novel potent drugs effective against human malignancies. Ion beams can be used to achieve therapeutic effects on tumors which are resistant to conventional radiation/photons. However the treatment planning system currently used in ion therapy centers are still based on data from conventional radiation to describe parameters for ion therapy. In paper I, we used two mathematical models to compare the cellular response to photons and ions. We found that the parameters determined for photons, using the RCR model could be used to predict the response to ion beams. The data also indicated that cells having efficient DNA repair capability are more sensitive to ion beams. In paper II, we compared photons and ion beams by analysis of the global phosphoproteome of a photon resistant cell line and identify signaling pathways responsible for photon resistance. We identified GSK3β to be important for cell proliferation and to have a protective effect on photon-induced tumor cell death. We also confirm the role of p38MAPK in photon resistance. Cells propagated on plastic surfaces in monolayer culture do not represent accurate models of in vivo tumor tissue. The 3-D microenvironment of tumor tissue, including the presence of hypoxic regions, is better mimicked using the multicellular tumor spheroid model. Spheroids can be used for drug screening projects aimed to identify compounds effective on solid tumors. In paper III, we describe a novel small molecule capable of inducing apoptosis in 3D tumor spheroids and xenograft tumors. The compound triggered rapid increases of intracellular calcium levels. The drug was effective in inducing cell death of all cells of colon cancer spheroids, including cells in the hypoxic nutrient deficient cores. Interestingly, and in contrast to cells in peripheral cell layers, apoptosis did not appear to be induced in the hypoxic core regions. The results showed that novel drugs can be identified which have significantly stronger cytotoxic effects on multicellular spheroids as compared to conventional cancer therapeutics. In paper IV, we report a novel inhibitor of the ubiquitin-proteasome system (UPS) that is cytotoxic to a number of cancer cell lines and patient tumor cells. This compound HRF-3, induces accumulation of polyubiquitinated proteins in the absence of a proteasomal blocking. Our results indicate that HRF-3 inhibits the UPS at a pre-proteasomal step and generates ROS similar to proteasomal inhibitors. Our data supports the notion that the UPS can be inhibited at several steps resulting in tumor cytotoxicity. In paper V, we identified the 19S DUB inhibitor b-AP15 analogue VLX1570 which has similar biochemical activity as the hit compound. VLX1570 has strong anti-tumor activity in multiple myeloma cells and is capable of overcoming bortezomib resistance. The findings suggest that VLX1570 is a promising candidate for the clinical drug development against multiple myeloma.
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| 3. |
- Mohanty, Chitralekha, et al.
(författare)
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Predicting the sensitivity to ion therapy based on the response to photon irradiation - experimental evidence and mathematical modelling
- 2014
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Ingår i: Anticancer Research. - 0250-7005 .- 1791-7530. ; 34:6, s. 2801-2806
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Tidskriftsartikel (refereegranskat)abstract
- Background/Aim: The use of ion radiation therapy is growing due to the continuously increasing positive clinical experience obtained. Therefore, there is a high interest in radio-biological experiments comparing the relative efficiency in cell killing of ions and photons as the photons are currently the main radiation modality used for cancer treatment. This comparison is particularly important since the treatment planning systems (TPSs) used at the main ion therapy centres make use of parameters describing the cellular response to photons, respectively ions, determined in vitro. It was therefore the aim of this paper to compare the effects of high LET ion radiation with low LET photons and determine whether the cellular response to low LET could predict the response to high LET irradiation. Materials and Methods: Clonogenic cell survival data of five tumor cell lines irradiated with different ion beams of similar, clinically-relevant, LET were studied in relation to the response to low LET photons. Two mathematical models were used to fit the data, the repairable-conditionally repairable damage (RCR) model and the linear quadratic (LQ) model. Results: The results indicate that the relative biological efficiency of the high LET radiation assessed with the RCR model could be predicted based only on the response to the low LET irradiation. Conclusion: The particular features of the RCR model indicate thus that tumor cells showing a large capacity for repairing the damage will have the larger benefit from radiation therapy with ions beams.
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| 4. |
- Wang, Xin, et al.
(författare)
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Synthesis and Evaluation of Derivatives of the Proteasome Deubiquitinase Inhibitor b-AP15
- 2015
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Ingår i: Chemical Biology and Drug Design. - : Wiley. - 1747-0277 .- 1747-0285. ; 86:5, s. 1036-1048
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Tidskriftsartikel (refereegranskat)abstract
- The ubiquitin-proteasome system (UPS) is increasingly recognized as a therapeutic target for the development of anticancer therapies. The success of the 20S proteasome core particle (20S CP) inhibitor bortezomib in the clinical management of multiple myeloma has raised the possibility of identifying other UPS components for therapeutic intervention. We previously identified the small molecule b-AP15 as an inhibitor of 19S proteasome deubiquitinase (DUB) activity. Building upon our previous data, we performed a structure-activity relationship (SAR) study on b-AP15 and identified VLX1570 as an analog with promising properties, including enhanced potency and improved solubility in aqueous solution. In silico modeling was consistent with interaction of VLX1570 with key cysteine residues located at the active sites of the proteasome DUBs USP14 and UCHL5. VLX1570 was found to inhibit proteasome deubiquitinase activity in vitro in a manner consistent with competitive inhibition. Furthermore, using active-site-directed probes, VLX1570 also inhibited proteasome DUB activity in exposed cells. Importantly, VLX1570 did not show inhibitory activity on a panel of recombinant non-proteasome DUBs, on recombinant kinases, or on caspase-3 activity, suggesting that VLX1570 is not an overtly reactive general enzyme inhibitor. Taken together, our data shows the chemical and biological properties of VLX1570 as an optimized proteasome DUB inhibitor.
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