title: A novel carbohydrate-based therapeutic GCS-100 overcomes bortezomib resistance and enhances dexamethasone-induced apoptosis in multiple myeloma cells.
abstract: Human multiple myeloma is a presently incurable hematologic malignancy, and novel biologically based therapies are urgently needed. GCS-100 is a polysaccharide derived from citrus pectin in clinical development for the treatment of cancer. Here we show that GCS-100 induces apoptosis in various multiple myeloma cell lines, including those resistant to dexamethasone, melphalan, or doxorubicin. Examination of purified patient multiple myeloma cells showed similar results. Specifically, GCS-100 decreases viability of bortezomib/PS-341-resistant multiple myeloma patient cells. Importantly, GCS-100 inhibits multiple myeloma cell growth induced by adhesion to bone marrow stromal cells; overcome the growth advantage conferred by antiapoptotic protein Bcl-2, heat shock protein-27, and nuclear factor-kappaB; and blocks vascular endothelial growth factor-induced migration of multiple myeloma cells. GCS-100-induced apoptosis is associated with activation of caspase-8 and caspase-3 followed by proteolytic cleavage of poly(ADP-ribose) polymerase enzyme. Combined with dexamethasone, GCS-100 induces additive anti-multiple myeloma cytotoxicity associated with mitochondrial apoptotic signaling via release of cytochrome c and Smac followed by activation of caspase-3. Moreover, GCS-100 + dexamethasone-induced apoptosis in multiple myeloma cells is accompanied by a marked inhibition of an antiapoptotic protein Galectin-3, without significant alteration in Bcl-2 expression. Collectively, these findings provide the framework for clinical evaluation of GCS-100, either alone or in combination with dexamethasone, to inhibit tumor growth, overcome drug resistance, and improve outcome for patients with this universally fatal hematologic malignancy.
authors.affiliation: The Jerome Lipper Multiple Myeloma Center, Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Dharminder
authors.initials: D
authors.lastname: Chauhan
authors.forename: Guilan
authors.initials: G
authors.lastname: Li
authors.forename: Klaus
authors.initials: K
authors.lastname: Podar
authors.forename: Teru
authors.initials: T
authors.lastname: Hideshima
authors.forename: Paola
authors.initials: P
authors.lastname: Neri
authors.forename: Deli
authors.initials: D
authors.lastname: He
authors.forename: Nicholas
authors.initials: N
authors.lastname: Mitsiades
authors.forename: Paul
authors.initials: P
authors.lastname: Richardson
authors.forename: Yan
authors.initials: Y
authors.lastname: Chang
authors.forename: Joanne
authors.initials: J
authors.lastname: Schindler
authors.forename: Bradley
authors.initials: B
authors.lastname: Carver
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Anderson
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001897:Boronic Acids / Q000008:administration & dosage / Q000494:pharmacology; D000069286:Bortezomib; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology; D015536:Down-Regulation; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004357:Drug Synergism; D037502:Galectin 3 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D020672:I-kappa B Proteins / Q000235:genetics / Q000378:metabolism; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects; D009101:Multiple Myeloma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D000072000:NF-KappaB Inhibitor alpha; D011134:Polysaccharides / Q000008:administration & dosage / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors; D011719:Pyrazines / Q000008:administration & dosage / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D001897:Boronic Acids; C505531:GCS-100; D037502:Galectin 3; D020672:I-kappa B Proteins; C000606204:NFKBIA protein, human; D011134:Polysaccharides; D019253:Proto-Oncogene Proteins c-bcl-2; D011719:Pyrazines; D042461:Vascular Endothelial Growth Factor A; D000072000:NF-KappaB Inhibitor alpha; D000069286:Bortezomib; D003907:Dexamethasone; D004317:Doxorubicin