Correlation between spontaneous metastatic potential and type I collagenolytic activity in a human pancreatic cancer cell line (SUIT-2) and sublines

A human pancreatic cancer cell line (SUIT-2) and four sublines cloned in vitro (S2-007, S2-013, S2-020 and S2-028) were inoculated into nude mice for assessment of metastatic potentials. After 16 weeks of subcutaneous injection, the parent SUIT-2 line metastasized to the lungs and lymph nodes in three of six mice. S2-007 cells presented the highest metastatic potential in pulmonary (5/6) and lymph node (2/6) metastases among the four sublines. No metastasis was found in S2-028. The incidence of spontaneous pulmonary metastasis was correlated with that of pulmonary colonization after intravenous (i.v.) injection of cell clusters (r = 0.87, P = 0.056). Pulmonary colonization potential using single cells, however, did not always reflect a spontaneous metastatic ability. Type I collagenolytic activity in serum-free conditioned media of these cells was correlated effectively with the incidence of spontaneous pulmonary metastasis (r = 0.92, P = 0.026) and pulmonary colonization after i.v. injection of cell clusters (r = 0.95, P = 0.013). Thus, type I collagenolytic activity may possibly be essential to spontaneous cancer metastasis.