IN-VITRO DETERMINATION OF BASEMENT-MEMBRANE INVASION PREDICTS LIVER METASTASES IN HUMAN GASTROINTESTINAL CARCINOMA

We described previously (H. Imamura, et at, Cancer Res., 54: 3620-3624 , 1994) a quantitative and reproducible (4,5-dimethylthiazol-2-yl)-2,5 -diphenyltetrazolium bromide (MTT) assay for tumor cell invasiveness t hat uses a water-repellent, paraffin-treated Chemotaxicell chamber to produce a uniform Matrigel layer, In the present experiments, we studi ed 71 human gastrointestinal carcinomas, including 53 maintained as xe nografts in nude mice and 18 fresh surgical specimens, We found a corr elation between metastatic behavior and the percent invasion (PI) calc ulated from the MTT assay. Tumors producing liver metastases had a sig nificantly higher PI than did tumors without liver metastases (P < 0.0 1), and seven of nine fresh tumors with a PI greater than 1.0 showed l iver metastases within 2 years. No significant correlations mere noted between the PI and clinicopathological factors. In the tumor xenograf ts, type IV collagenase activity was significantly higher in tumors wi th clinically evident liver metastases than in those without liver met astases (P < 0.05). Colorectal carcinomas with liver metastases and a high PI showed higher expression of matrix metalloproteinase 9 than ma trix metalloproteinase 2 as assessed by gelatin zymography. Thus, the invasion-MTT assay is clinically useful for predicting liver metastase s. Type IV collagenase plays an important role in the development of l iver metastases from human gastrointestinal carcinoma.