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Melanoma Res. 2008 Apr;18(2):73-84. doi: 10.1097/CMR.0b013e3282f7c8f9.

A single chain immunotoxin, targeting the melanoma-associated chondroitin sulfate proteoglycan, is a potent inducer of apoptosis in cultured human melanoma cells.

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University of Erlangen-Nuremberg, Erlangen, Germany.


A recombinant immunotoxin was constructed by fusing a single chain fragment variable antibody fragment, specific for the melanoma-associated chondroitin sulfate proteoglycan (MCSP), to a truncated variant of Pseudomonas exotoxin A (ETA'), carrying a C-terminal KDEL-peptide for improved retrograde intracellular transport. The resulting immunotoxin MCSP-ETA' was periplasmatically expressed in Escherichia coli and purified under native conditions by affinity chromatography resulting in a yield of approximately 30 mug/l bacterial culture. This immunotoxin induced antigen-specific apoptosis in the cultured human melanoma-derived cell lines A2058 and A375M, and treatment with a single dose of the agent eliminated up to 80% of these cells within 72 h. The dose needed for half-maximum killing (EC50) was approximately 1 nmol/l for both cell lines. MCSP-ETA' also displayed cytotoxic activity against cultured primary melanoma cells from patients with advanced disease (pathologic stages IIIC and IV), with net cell death reaching up to 70% within 96 h after treatment with a single dose of 14 nmol/l. MCSP-ETA' induced cell death synergistically with cyclosporin A, both in established human melanoma cell lines and cultured primary melanoma cells. The distinctive antigen-restricted induction of apoptosis and the synergy with cyclosporin A justify further evaluation of this novel agent with regard to its potential application for the treatment of malignant melanoma.

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