title: The immunocytokine scFv23/TNF sensitizes HER-2/neu-overexpressing SKBR-3 cells to tumor necrosis factor (TNF) via up-regulation of TNF receptor-1.
abstract: Overexpression of HER-2/neu confers cellular resistance to tumor necrosis factor (TNF)-mediated cytotoxicity to SKBR-3 breast cancer cell lines. To understand the correlation between HER-2/neu expression and TNF resistance, we examined the unique signaling pathways associated with the cytotoxic effects of the immunocytokine scFv23/TNF, recombinant single-chain antibody fusion constructs containing TNF and targeting HER-2/neu, in TNF-resistant SKBR-3-LP cells. We found that treatment of HER-2/neu-overexpressing SKBR-3-LP cells with scFv23/TNF resulted in a 5- to 7-fold higher level of TNF receptor-1 expression 48 hours after exposure. In addition, treatment of SKBR-3-LP cells with scFv23/TNF resulted in down-regulation of Akt phosphorylation and induced apoptosis through cleavage of caspase-8, caspase-3, and poly(ADP-ribose) polymerase. ScFv23/TNF-induced cytotoxicity was inhibited by blocking of the binding of the TNF component of scFv23/TNF to TNF receptor-1 and was dependent on activation of caspase-8 and caspase-3. These results indicate that the immunocytokine scFv23/TNF sensitizes TNF-resistant HER-2/neu-overexpressing SKBR-3-LP cells to TNF-induced apoptosis via the overexpression of TNF receptor-1 and suggest that the overexpression of TNF receptor-1 plays a crucial role in TNF sensitivity in HER-2/neu-overexpressing cancer cells. ScFv23/TNF targeting the HER-2/neu may be an effective cytotoxic agent against HER-2/neu-overexpressing cancer cells, which are inherently resistant to TNF.
authors.affiliation: Immunopharmacology and Targeted Therapy Section, Department of Experimental Therapeutics, The University of Texas M D Anderson Cancer Center, Unit 044, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
authors.forename: Mi-Ae
authors.initials: MA
authors.lastname: Lyu
authors.forename: Michael G
authors.initials: MG
authors.lastname: Rosenblum
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use / Q000633:toxicity*; D017209:Apoptosis; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D005260:Female; D006801:Humans; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000627:therapeutic use / Q000633:toxicity*; D015398:Signal Transduction / Q000187:drug effects; D057127:Single-Chain Antibodies; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000633:toxicity*; D015854:Up-Regulation
chemical_list: D000970:Antineoplastic Agents; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases; D018719:Erb-b2 Receptor Tyrosine Kinases; D047888:Receptors, Tumor Necrosis Factor, Type I; D011993:Recombinant Fusion Proteins; D057127:Single-Chain Antibodies; D014409:Tumor Necrosis Factor-alpha; C505209:ScFv23-TNF fusion protein; C505407:CASP3 protein, human; C505530:CASP8 protein, human