Oligonucleotides blocking glucosylceramide synthase expression selectively reverse drug resistance in cancer cells

• Main Authors: Yong-Yu Liu, Tie Yan Han, Jing Yuan Yu, Arie Bitterman, Ahn Le, Armando E. Giuliano, Myles C. Cabot
• Format: Article
• Language: English
• Published: Elsevier 2004-05-01
• Series: Journal of Lipid Research
• Subjects: ceramide; antisense oligonucleotides; apoptosis; chemotherapy; breast cancer; doxorubicin
• Online Access: http://www.sciencedirect.com/science/article/pii/S0022227520318344

High glucosylceramide synthase (GCS) activity is one factor contributing to multidrug resistance (MDR) in breast cancer. Enforced GCS overexpression has been shown to disrupt ceramide-induced apoptosis and to confer resistance to doxorubicin. To examine whether GCS is a target for cancer therapy, we have designed and tested the effects of antisense oligodeoxyribonucleotides (ODNs) to GCS on gene expression and chemosensitivity in multidrug-resistant cancer cells. Here, we demonstrate that antisense GCS (asGCS) ODN-7 blocked cellular GCS expression and selectively increased the cytotoxicity of anticancer agents. Pretreatment with asGCS ODN-7 increased doxorubicin sensitivity by 17-fold in MCF-7-AdrR (doxorubicin-resistant) breast cancer cells and by 10-fold in A2780-AD (doxorubicin-resistant) ovarian cancer cells. In MCF-7 drug-sensitive breast cancer cells, asGCS ODN-7 only increased doxorubicin sensitivity by 3-fold, and it did not influence doxorubicin cytotoxicity in normal human mammary epithelial cells. asGCS ODN-7 was shown to be more efficient in reversing drug resistance than either the GCS chemical inhibitor d-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol or the P-glycoprotein blocking agents verapamil and cyclosporin A. Experiments defining drug transport and lipid metabolism parameters showed that asGCS ODN-7 overcomes drug resistance mainly by enhancing drug uptake and ceramide-induced apoptosis.This study demonstrates that a 20-mer asGCS oligonucleotide effectively reverses MDR in human cancer cells.