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

Ralph J Abi-Habib1, Ravibhushan Singh, Shihui Liu

  • 1Cancer Research Institute of Scott & White Memorial Hospital, Temple, Texas 76502, USA.

Molecular Cancer Therapeutics
|October 17, 2006
PubMed

Insights

A novel toxin, PrAgU2/FP59, targets urokinase plasminogen activator (uPA)-expressing tumors selectively. This engineered anthrax toxin shows high potency against various cancer cells, offering a promising new therapeutic strategy.

Area of Science:

  • Oncology
  • Biochemistry
  • Molecular Biology

Background:

  • Urokinase plasminogen activator (uPA) is a tumor-specific protease overexpressed in many solid tumors.
  • Current strategies targeting the urokinase system primarily inhibit tumor growth, not induce regression.

Purpose of the Study:

  • To evaluate the efficacy and selectivity of a novel recombinant toxin, PrAgU2/FP59, engineered to target uPA-expressing tumor cells.
  • To identify predictive biomarkers for tumor cell sensitivity to PrAgU2/FP59.

Main Methods:

  • Engineering a recombinant anthrax toxin (PrAgU2/FP59) with a urokinase activation site.
  • Assessing PrAgU2/FP59 toxicity against diverse tumor cell lines and normal human cells in vitro and in vivo.
  • Analyzing the correlation between toxin potency and the expression levels of anthrax toxin receptor, uPA, and uPA receptor.

Main Results:

  • PrAgU2/FP59 demonstrated potent toxicity against a broad spectrum of tumor cell lines, including lung, pancreatic, and breast cancers.
  • Most resistant tumor cells became sensitive to PrAgU2/FP59 upon addition of exogenous pro-uPA.
  • PrAgU2/FP59 exhibited significantly lower toxicity towards normal human cells, indicating high selectivity.
  • Toxin efficacy was dependent on anthrax toxin receptor, uPA, and uPA receptor levels.

Conclusions:

  • PrAgU2/FP59 is a highly potent and selective toxin capable of targeting uPA-expressing tumor cells irrespective of their origin.
  • Anthrax toxin receptor, uPA, and uPA receptor serve as reliable predictors of tumor cell sensitivity to PrAgU2/FP59 therapy.

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