Inhibition of growth of HeLa cells by new synthetic protease inhibitors

Tryptic hydrolysis of benzoyl-DL-arginine p-nitroanilide was competitively inhibited by phenyl and substituted phenyl esters of trans-4-guanidinomethylcyclohexanecarboxylic acid (GMCHA), amidinopiperidine-4-carboxylic acid (APCA), amidinopiperidine-3-carboxylic acid (AP3CA), amidinopiperidine-4-acetic acid (APAA), amidinopiperidine-4-propionic acid (APPA), amidinopiperidine-3-propionic acid (AP3PA), amidinopiperidine-4-butyric acid (APBA), and amidinopiperidine-3-butyric acid (AP3BA). The 4-tert-butylphenyl (tBP) ester of APPA was the most effective inhibitor, its K1 value being 5.0 X 10(-7) M. The free acids and phenols had no inhibitory effect at 10(-3) M. The tBP esters of GMCHA, APPA, and APBA caused 50-60% inhibition of growth of HeLa cells, their effects being dose-dependent, while same esters of APCA, AP3PA, APPA, AP3PA, and AP3BA inhibited the growth by 30-40%. The phenyl esters of these were less inhibitory than the tBP esters. A protease preparation obtained from HeLa cells by sonication and ultrafiltration through a molecular sieve membrane strongly hydrolyzed the fluorescent peptides Boc-Val-Pro-Arg-MCA and Bz-Arg-MCA. This proteolytic activity was not affected by soybean trypsin inhibitor but was strongly inhibited by the tBP esters of GMCHA, APAA, and APBA, their effects roughly paralleling their inhibitions of the growth of HeLa cells.