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MRP1 and glucosylceramide are coordinately over expressed and enriched in rafts during multidrug resistance acquisition in colon cancer cells
Author(s) -
Klappe Karin,
Hinrichs John W.J.,
Kroesen BartJan,
Sietsma Hannie,
Kok Jan Willem
Publication year - 2004
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.20140
Subject(s) - downregulation and upregulation , efflux , sphingolipid , colchicine , multiple drug resistance , biology , microbiology and biotechnology , cell culture , biochemistry , gene , genetics , antibiotics
Previously we have described a novel multidrug‐resistant cell line, HT29 col , which displayed over expression of the multidrug‐resistance protein 1 (MRP1) and an altered sphingolipid composition, including enhanced levels of glucosylceramide (GlcCer; Kok JW, Veldman RJ, Klappe K, Koning H, Filipeanu C, Muller M. Int J Cancer 2000;87:172–8). In our study, long‐term screening revealed that, during colchicine‐induced acquisition of multidrug resistance in a new HT29 col cell line, increases in GlcCer occurred concomitantly with upregulation of MRP1 expression. Both MRP1 and GlcCer were found enriched in Lubrol‐insoluble membrane domains. The expression of MRP1 and GlcCer were tightly correlated, as indicated also by a reversal of both at the later stage of colchicine consolidation. Resistance to colchicine was determined by MRP1, while glucosylceramide synthase (GCS) did not contribute: 1) Resistance was fully inhibited by MK571. 2) GCS expression and activity were not upregulated in HT29 col cells. 3) Inhibition of GCS did not affect MRP1‐mediated efflux function or sensitivity to colchicine. Instead, overall sphingolipid metabolism was upregulated through an increased rate of ceramide biosynthesis. In conclusion, upregulation of MRP1 occurs in concert with upregulation of GlcCer during multidrug‐resistance acquisition, and both are enriched in rafts. The increased GlcCer pool does not directly modulate MRP1 function and cell survival. © 2004 Wiley‐Liss, Inc.