A urokinase-activated recombinant anthrax toxin is selectively cytotoxic to many human tumor cell types

Abstract

Urokinase plasminogen activator (uPA) is a tumor-specific protease highly expressed in several types of solid tumors and rarely present on normal cells under physiologic conditions. Due to its high expression on metastatic tumors, several different strategies have been used to target the urokinase system. These have mostly led to tumor growth inhibition rather than tumor regression. A different approach was adopted by replacing the furin activation site on a recombinant anthrax toxin with a urokinase activation site. The resulting toxin, PrAgU2/ FP59, was highly potent against tumors both in vitro and in vivo. In this study, we show that PrAgU2/FP59 is toxic to a wide range of tumor cell lines, including non -small cell lung cancer, pancreatic cancer, and basal-like breast cancer cell lines. Of the few cell lines found to be resistant to PrAgU2/FP59, most became sensitive upon addition of exogenous pro-uPA. PrAgU2/FP59 was much less toxic to normal human cells. The potency of PrAgU2/FP59 was dependent on anthrax toxin receptor, uPA receptor, and uPA levels but not on total plasminogen activator inhibitor-1 levels. In this study, we show that PrAgU2/FP59 is a wide-range, highly potent, and highly selective toxin that is capable of specifically targeting uPA-expressing tumor cells, independently of the tissue of origin of these cells.Furthermore, we identify three molecular markers, anthrax toxin receptor, uPA, and uPA receptor, which can be used as predictors of tumor cell sensitivity to PrAgU2/FP59.

Heterodimeric integrin complexes containing β1-integrin promote internalization and lethality of anthrax toxin

“…Diverse cell lines treated with LF-PA show a wide range of sensitivities to the toxin (9,(20)(21)(22)(23)(24)(25), and cell death occurs only in cells that have impaired MAPK kinase function (21). We hypothesized that such phenotypic differences might enable microarray-based identification of other genes whose differentially elevated or reduced expression correlates with differential toxin lethality.…”

“…GABRIEL software (26) separated cancer cell lines (SK-MEL-5, SK-MEL28, M-14, MALME-3M, MDA-MB-435, MDA-N, SK-MEL-2, HL-60, MCF7, SW-620, EKVX, and A549) into two groups, LF-PA-sensitive and LF-PA-resistant, based on previous reports (9,(20)(21)(22)(23)(24)(25). GABRIEL (27) was used for correlation of steady-state levels of expression with toxin lethality.…”

In vitro- and in vivo-targeted tumor lysis by an MMP2 cleavable melittin-LAP fusion protein

“…Different types of cytolytic toxins, such as anthrax toxin, aerolysin, two-chain ·-hemolysin, and hecate have been used in fusion proteins or conjugates to either directly target the tumor cell surface through ligands and receptors, or be activated through tumor-specific proteases, such as urokinase, PSA, cathepsin B and MMPs (16)(17)(18)(19). In a previous study, we have shown that an MMP2 cleavable melittin, the poreforming toxin from honey bee, conjugated with avidin can specifically target tumor cells in vitro and in vivo (20).…”

Potential markers for early diagnostics of Colorectal cancer and Inflammatory bowel disease in humans : intestinal microorganisms and immune system (teammates or rivals)

“…Duration and severity of inflammation increases the risk of Colorectal cancer (CRC) development by about 60% in IBD patients [5]. Chronic inflammation represents the appropriate microenvironment for tumor development via stimulation of immune cells [6].…”