A new Mixed-Backbone Oligonucleotide Against Glucosylceramide Synthase Sensitizes Multidrug-Resistant Tumors to Apoptosis

Funding Source

National Institutes of Health, Department of Defense Breast Cancer Research Program, United States Public Health Service/NIGMS, Louisiana Board of Regents

Grant Number

P20 RR16456,GM77391 (M.C.C), CA088932 (B.O), CA097132 (B.O.), LEQSF RD-A-19 (Q.Z.) DE016572 (B.O.),


Department of Biology

Document Type


Publication Date



Enhanced ceramide glycosylation catalyzed by glucosylceramide synthase (GCS) limits therapeutic efficiencies of antineoplastic agents including doxorubicin in drug-resistant cancer cells. Aimed to determine the role of GCS in tumor response to chemotherapy, a new mixed-backbone oligonucleotide (MBO-asGCS) with higher stability and efficiency has been generated to silence human GCS gene. MBO-asGCS was taken up efficiently in both drug-sensitive and drug-resistant cells, but it selectively suppressed GCS overexpression, and sensitized drug-resistant cells. MBO-asGCS increased doxorubicin sensitivity by 83-fold in human NCI/ADR-RES, and 43-fold in murine EMT6/AR1 breast cancer cells, respectively. In tumor-bearing mice, MBO-asGCS treatment dramatically inhibited the growth of multidrug-resistant NCI/ADR-RE tumors, decreasing tumor volume to 37%, as compared with scrambled control. Furthermore, MBO-asGCS sensitized multidrug-resistant tumors to chemotherapy, increasing doxorubicin efficiency greater than 2-fold. The sensitization effects of MBO-asGCS relied on the decreases of gene expression and enzyme activity of GCS, and on the increases of C18-ceramide and of caspase-executed apoptosis. MBO-asGCS was accumulation in tumor xenografts was greater in other tissues, excepting liver and kidneys; but MBO-asGCS did not exert significant toxic effects on liver and kidneys. This study, for the first time in vivo, has demonstrated that GCS is a promising therapeutic target for cancer drug resistance, and MBO-asGCS has the potential to be developed as an antineoplastic agent.


DOI: 10.1371/journal.pone.0006938

PubMed ID: 19742320

Funding: This work was supported by United State Public Health Service/NIH grant P20 RR16456 from the NCRR (Y.Y.L, S.M.J), and Department of Defense Breast Cancer Research Program DAMD17-01-1-0536 (Y.Y.L.). This work was partially supported by United States Public Health Service/NIGMS grant GM77391 (M.C.C), CA088932 (B.O), CA097132 (B.O.), DE016572 (B.O.), Louisiana Board of Regents, LEQSF RD-A-19 (Q.Z.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.