title: Targeted apoptosis activation with GrB/scFvMEL modulates melanoma growth, metastatic spread, chemosensitivity, and radiosensitivity.
abstract: GrB/scFvMEL, a fusion protein composed of human granzyme B (GrB) and the single-chain antibody scFvMEL, targets melanoma gp240 antigen and exerts impressive cytotoxic effects by inducing apoptosis. We evaluated the effects of GrB/scFvMEL on chemotherapy, radiation therapy, metastasis in vitro, and the growth of human melanoma A375 xenograft tumors in nude mice. GrB/scFvMEL showed synergistic cytotoxicity when coadministered with doxorubicin, vincristine or cisplatin, and additive effects, in combination with etoposide or cytarabine. Optimal cytotoxic effects were obtained when cells were treated first with GrB/scFvMEL followed by exposure to the agent (rather than the reverse). Pretreatment of A375 cells with GrB/scFvMEL significantly sensitized melanoma cells to ionizing radiation assessed using a clonogenic survival assay. Subtoxic doses of GrB/scFvMEL inhibited the invasion of A375 cells into Matrigel. GrB/scFvMEL (37.5 mg/kg) was administered intravenously to nude mice bearing A375 tumors. Saline-treated tumors increased 24-fold, whereas tumors treated with GrB/scFvMEL showed a significant tumor growth delay increasing four-fold. Tumor tissue displayed an increase in apoptotic nuclei compared to control. Thus, the targeted delivery of GrB to tumors may have a significant potential for cancer treatment. Targeted therapeutic agents specifically designed to impact cellular apoptotic pathways may represent a novel class of therapeutic agents.
authors.affiliation: Immunopharmacology and Targeted Therapy Section, Department of Experimental Therapeutics, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
authors.forename: Yuying
authors.initials: Y
authors.lastname: Liu
authors.forename: Weihe
authors.initials: W
authors.lastname: Zhang
authors.forename: Ting
authors.initials: T
authors.lastname: Niu
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Cheung
authors.forename: Anupama
authors.initials: A
authors.lastname: Munshi
authors.forename: Raymond E
authors.initials: RE
authors.lastname: Meyn
authors.forename: Michael G
authors.initials: MG
authors.lastname: Rosenblum
mesh_terms: D000818:Animals; D000912:Antibodies, Neoplasm / Q000235:genetics / Q000502:physiology*; D017209:Apoptosis / Q000502:physiology*; D002455:Cell Division; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000502:physiology*; D004195:Disease Models, Animal; D053804:Granzymes; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000502:physiology*; D008545:Melanoma / Q000473:pathology*; D051379:Mice; D008819:Mice, Nude; D009362:Neoplasm Metastasis; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D012878:Skin Neoplasms / Q000473:pathology; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured
chemical_list: D000912:Antibodies, Neoplasm; D007135:Immunoglobulin Variable Region; D011993:Recombinant Fusion Proteins; C509213:GZMB protein, human; D053804:Granzymes; C509214:Gzmb protein, mouse; D012697:Serine Endopeptidases