Targeting sphingosine kinase 1 in carcinoma cells decreases proliferation and survival by compromising PKC activity and cytokinesis

Kotelevets, Nataliya; Fabbro, Doriano; Huwiler, Andrea; Zangemeister-Wittke, Uwe (2012). Targeting sphingosine kinase 1 in carcinoma cells decreases proliferation and survival by compromising PKC activity and cytokinesis. PLoS ONE, 7(6), e39209. Lawrence, Kans.: Public Library of Science 10.1371/journal.pone.0039209

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Sphingosine kinases (SK) catalyze the phosphorylation of proapoptotic sphingosine to the prosurvival factor sphingosine 1-phosphate (S1P), thereby promoting oncogenic processes. Breast (MDA-MB-231), lung (NCI-H358), and colon (HCT 116) carcinoma cells were transduced with shRNA to downregulate SK-1 expression or treated with a pharmacologic SK-1 inhibitor. The effects of SK-1 targeting were investigated by measuring the level of intracellular sphingosine, the activity of protein kinase C (PKC) and cell cycle regulators, and the mitotic index. Functional assays included measurement of cell proliferation, colony formation, apoptosis, and cell cycle analysis. Downregulation of SK-1 or its pharmacologic inhibition increased intracellular sphingosine and decreased PKC activity as shown by reduced phosphorylation of PKC substrates. In MDA-MB-231 cells this effect was most pronounced and reduced cell proliferation and colony formation, which could be mimicked using exogenous sphingosine or the PKC inhibitor RO 31-8220. SK-1 downregulation in MDA-MB-231 cells increased the number of cells with 4N and 8N DNA content, and similar effects were observed upon treatment with sphingosine or inhibitors of SK-1 or PKC. Examination of cell cycle regulators unveiled decreased cdc2 activity and expression of Chk1, which may compromise spindle checkpoint function and cytokinesis. Indeed, SK-1 kd cells entered mitosis but failed to divide, and in the presence of taxol also failed to sustain mitotic arrest, resulting in further increased endoreduplication and apoptosis. Our findings delineate an intriguing link between SK-1, PKC and components of the cell cycle machinery, which underlines the significance of SK-1 as a target for cancer therapy.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Pharmacology

UniBE Contributor:

Kotelevets, Nataliya; Fabbro, Doriano; Huwiler, Andrea and Zangemeister-Wittke, Uwe

Subjects:

600 Technology > 610 Medicine & health

ISSN:

1932-6203

Publisher:

Public Library of Science

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 14:35

Last Modified:

18 Feb 2016 14:26

Publisher DOI:

10.1371/journal.pone.0039209

PubMed ID:

22761740

Web of Science ID:

000305781700024

BORIS DOI:

10.7892/boris.14087

URI:

https://boris.unibe.ch/id/eprint/14087 (FactScience: 220894)

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