Abstract 3441: Silencing glucosylceramide synthase using MBO-asGCS eliminates tumor metastasis

Abstract

Abstract Disseminated metastasis is often observed in cancer patients fail in chemotherapy. Tumor metastasis is known to rely on the interaction of cancer cells and the extracellular matrix components but the molecular mechanism by which drug resistance promotes tumor metastasis is still not clear. Glucosylceramide synthase (GCS) that is a limiting enzyme for ceramide glycosylation and regulates glycosphingolipid (GSL) synthesis can cause drug resistance. Hence we report that GCS is a determinant of metastatic properties of drug-resistant cancer cells, and silencing GCS eliminates tumor metastasis. Our recent study found that the metastatic potency of drug-resistant cancer cells depended on the overexpression of GCS. Compared with drug-sensitive MCF-7 cells, the wound healing, matrigel attachment and MMP-9 activity significantly was 1.5 fold faster, 3 fold more and 2 folds higher respectively in the drug resistant MCF-7/Dox that also had 39-fold higher GCS protein level and 2-fold higher GCS enzyme activity. Introduction of GCS gene enhanced the metastatic potency of MCF-7 cells, because its matrigel attachment and invasion potential significantly increased by 2-fold and 1.5-fold after transfection. In contrast, silencing GCS by using mixed-backbone oligonucleotide against GCS (MBO-asGCS, 100 nM) substantially diminished the metastatic potency of MCF-7/Dox cells, as the wound healing, matrigel attachment and invasion reduced by 2-fold, 1.5-fold and 3-fold respectively. MBO-asGCS treatments eliminated lung metastasis of MCF-7/Dox tumors. Further mechanistic studies disclosed that silencing GCS by MBO-asGCS decreased its expression and enzyme activity and also decreased the levels of globo-series glycosphingolipids (GSLs) in GSL-enriched microdomain located on the plasma membrane. Sequentially, silencing GCS decreased the expression levels of uPA, MMP-9, VEGF and FGF-2 that actively mediated the migration and invasion of cancer cells. This study thus indicates that GCS is determinant for the metastatic potency of drug-resistant cancer cells and silencing GCS by using MBO-asGCS is an effective approach to target the metastasis of tumor with drug resistance. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3441. doi:1538-7445.AM2012-3441