Studies on Protease Inhibitor Isolated from Breast Cancer and Breast Cancer Cell Line

2)通过木瓜酶-琼脂糖亲和层析和Sephacryl S-200凝胶过滤，从人乳腺癌和正常乳腺提取液中分离纯化出两种TPI：低分子量TPI和高分子量TPI。凝胶过滤测得它们的相对分子质量分别为14,000和90,000。3)低分子量(LMW-)TPI比高分子量(HMW-)TPI具有更高的比活性。在乳腺癌组织提取液中，LMW-TPI占主导地位，而在正常腺体提取液中，HMW-TPI占主导地位。4)只有HMW-TPI与抗尿硫醇蛋白水解酶抑制物(UTPI)兔免疫球蛋白通过双向免疫扩散和免疫电泳法反应。6)LMW-TPI对热和pH变化都是稳定的。7)也从人乳腺癌细胞系(YMB-L)中纯化了TPI。从培养细胞中提取的两种TPI均被证实为LMW-TPI，乳腺癌细胞产生HMW-TPI的能力可能低于正常乳腺细胞。HMW-TPI和LMW-TPI对抗UTPI-Ig G的抗原性差异可能在不久的将来用于诊断。

1) TPIs in human breast cancer extracts were significantly higher than in normal mammary gland extracts.2) TPI was purified from both human breast cancer and human normal mammary gland extracts by papain-Sepharose affinity chromatography and Sephacryl S-200 gel filtration.Two kinds of TPIs (Iow-molecular weight TPI and high-molecular weight TPI) were purified from both tissues. Their molecular weights were 14,000 and 90,000,respectively as determined by gel filtration.3) Low-molecular weight (LMW-) TPI had higher specific activity than high-molecular weight (HMW-) TPI. In breast cancer tissue extracts,LMW-TPI was dominant,Contrarily,HMW-TPI was dominant in normal gland tissue extracts.4) Only HMW-TPI reacted with anti-urinary thiol protease inhibitor (UTPI) rabbit IgG by double immunodiffusion and immunoelectrophoresis.5) LMW-TPI inhibited papain competitively using S-2302 as substrate.Its km and ki were 1.3x <10^(-3)> M and 6.1x <10^(-8)> M, respectively.6) LMW-TPI was found to be stable to heat and pH variation.7) TPIs were also purified from the human breast cancer cell line (YMB-l) . Both TPIs which were extracted from cultured cells and released into the medium, were confirmed to be LMW-TPI.Breast cancer cells may have lower ability to produce HMW-TPI than normal mammary gland cells. The difference of antigenicity to anti-UTPI IgG between HMW-TPI andLMW-TPI may be useful for diagnosis in near future.