Novel Apoptotic Protease Activated in Human Breast Cancer Cells after Poisoning Topoisomerase I

摘要

The goal of this grant is to clone the unknown protease activated by the active anti-breast cancer agent, Beta-lapachone (Beta-lap). The research team showed for the first time that Beta-lap requires NQ01 1, a two-electron reduction enzyme elevated in many human breast cancers, for activation. The team then characterized the unknown apoptotic protease activated in human breast cancer cells by Beta-lap, defining endpoints which will be essential for the ultimate isolation of this novel apoptotic protease. The unknown protease: (a) is a non-caspase cytsteine protease; (b) cleaves p53, lamin Beta and PARP (atypically) in an NQO1-dependent manner at a time co-incident with calpain activation (appearance of an 18 kDa active form and its movement into the nucleus by confocal microscopy); and (c) is calcium-dependent, where BAPTA-AM and EDTA blocked cell death caused by Beta-lap. Cloning the unknown protease activated by Beta- lap is ongoing by this research team using standard biochemical methodology and p53 and/or PARP cleavage site identification.