腫瘤的發生機制至今仍不清楚。腫瘤的可怕，在於其易於轉移，一旦發現時經常已有部分腫瘤細胞轉移至人體其他部位而不易以外科手術方法清除， 造成癌症之再次發生.利用具有高度轉移力之細胞株， 包括老鼠黑色素瘤細胞 B16-F10、 人類纖維肉瘤細胞HT-1080 與低轉移力之細胞株 - 老鼠黑色素瘤 B16-F1、人類胚胎正常肺纖維細胞 MRC-5，作為抗癌症轉移物質之篩選模式，對台灣極端環境，如森林土、溫泉土、湖畔土、果園根圈之土壤中分離之 100 株本土絲狀真菌分離株之發酵萃取液進行篩選， 應用美國國家癌症研究所 (US National Cancer Institute; 簡稱 NCI) 所發展的 sulforhodamine (SRB) 染色方法進行細胞毒性試驗， 篩選對高度轉移力之細胞株 B16-F10、HT1080 具有高生長抑制效應， 而對低轉移力之 B16-F1、MRC-5 不具抑制作用或作用極低之生物活性物質，同時以人類肝癌細胞株 Hep G2 和人類血癌細胞株 K562 作為篩選物質對不同癌細胞專一性之對照，結果顯示某些分離株萃取物含具有抗癌症轉移作用之生物活性物質存在。本篇報告將介紹此生物活性物質篩選系統之篩選方法並利用此篩選系統所進行之篩選工作。

A malignant tumor is hard to eradicate by removing the mass surgically because the abnormal cells often metastasize. How to find and kill these metastatic cells is an important key to cure cancer. We have isolated over 100 filamentous fungi from soil of extreme environments in Taiwan, including forest, hot spring, lake and fruit tree rhizosphere in order to screen some biologically active compounds. Screening of antimetastatic compounds, we used a set of highly metastatic cell lines, B16-F10 (mouse, melanoma) and HT-1080 (human, fibrosarcoma) and cell lines with low metastatic ability, B16-F1 (mouse,melanoma) and MRC-5 (human, lung, normal diploid fibroblast). Cultures grown in microtiter plates were assayed by SRB (sulforhodamine B) method. The goal for this screening program is to isolate biologically active compounds that can inhibit the growth of highly metastatic cells such as B16-F10 and HT-1080 but little effect on low metastatic cells such as B10-F1 and MRC-5. Some strains' media showed significant differences in cytotoxicity between the highly metastatic cells and the low metastatic cells. These results suggest that some products in these media may contain metastasis-specific or cell-specific toxins.