| 1. |
- Pellegrini, Paola, et al.
(författare)
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A drug screening assay on cancer cells chronically adapted to acidosis
- 2018
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Ingår i: Cancer Cell International. - : BMC. - 1475-2867. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Background: Drug screening for the identification of compounds with anticancer activity is commonly performed using cell lines cultured under normal oxygen pressure and physiological pH. However, solid tumors are characterized by a microenvironment with limited access to nutrients, reduced oxygen supply and acidosis. Tumor hypoxia and acidosis have been identified as important drivers of malignant progression and contribute to multicellular resistance to different forms of therapy. Tumor acidosis represents an important mechanism mediating drug resistance thus the identification of drugs active on acid-adapted cells may improve the efficacy of cancer therapy. Methods: Here, we characterized human colon carcinoma cells (HCT116) chronically adapted to grow at pH 6.8 and used them to screen the Prestwick drug library for cytotoxic compounds. Analysis of gene expression profiles in parental and low pH-adapted cells showed several differences relating to cell cycle, metabolism and autophagy. Results: The screen led to the identification of several compounds which were further selected for their preferential cytotoxicity towards acid-adapted cells. Amongst 11 confirmed hits, we primarily focused our investigation on the benzoporphyrin derivative Verteporfin (VP). VP significantly reduced viability in low pH-adapted HCT116 cells as compared to parental HCT116 cells and normal immortalized epithelial cells. The cytotoxic activity of VP was enhanced by light activation and acidic pH culture conditions, likely via increased acid-dependent drug uptake. VP displayed the unique property to cause light-dependent cross-linking of proteins and resulted in accumulation of polyubiquitinated proteins without inducing inhibition of the proteasome. Conclusions: Our study provides an example and a tool to identify anticancer drugs targeting acid-adapted cancer cells.
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| 2. |
- Zhang, Xiaonan, et al.
(författare)
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The deubiquitinase inhibitor b-AP15 induces strong proteotoxic stress and Check for mitochondrial damage
- 2018
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Ingår i: Biochemical Pharmacology. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0006-2952 .- 1356-1839 .- 1873-2968. ; 156, s. 291-301
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Tidskriftsartikel (refereegranskat)abstract
- Human cancers are characterized by intrinsic or acquired resistance to apoptosis and evasion of apoptosis has been proposed to contribute to treatment resistance. Bis-benzylidine piperidone compounds, containing alpha,beta-unsaturated carbonyl functionalities, have been extensively documented as being effective in killing apoptosis-resistant cells and to display promising antineoplastic activities in a number of tumor models. We here explored the phenotypic response of colon cancer cells to b-AP15, a bis-benzylidine piperidone previously shown to inhibit the proteasome deubiquitinases (DUBs) USP14 and UCHL5. Whereas similar overall mRNA and protein expression profiles were induced by b-AP15 and the clinically available proteasome inhibitor bortezomib, b-APIS induced stronger increases of chaperone expression. b-AP15 also induced a stronger accumulation of polyubiquitinated proteins in exposed cells. These proteins were found to partially colocalize with organelle structures, including mitochondria. Mitochondrial oxidative phosphorylation decreased in cells exposed to b-APIS, a phenomenon enhanced under conditions of severe proteotoxic stress caused by inhibition of the VCP/p97 ATPase and inhibition of protein translocation over the ER. We propose that mitochondrial damage caused by the association of misfolded proteins with mitochondrial membranes may contribute to the atypical cell death mode induced by b-AP15 and related compounds. The robust mode of cell death induction by this class of drugs holds promise for treatment of tumor cells characterized by apoptosis resistance.
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