IL-10 BLOCKS COLLAGEN-IV INVASION BY INVASION STIMULATING FACTOR-ACTIVATED PC-3 ML CELLS - UP-REGULATION OF TIMP-1 EXPRESSION

We have previously shown that a 78-kDa ''invasion stimulating factor'' (ISF) triggers collagenase IV (MMP-2) secretion and the invasive behavior of metastatic PC-3 ML subclones in modified Boyden chamber assays [Steams, M. E.; Steams, M. Autocrine factors, type TV collagenase secretion and prostatic cancer cell invasion. Cancer Metastasis Rev. 12:39-52; 1993. Wang, M.; Steams, M.; Steams, M. E. Identification of the receptor for a novel M(r) 78,000 ''invasion stimulating factor'' from metastatic human prostatic PC-3 ML clones. Cancer Res. 54:2492-2495; 1994.]. Recently, we have shown that interleukin 10 (IL-10) preferentially stimulates tissue inhibitor of metalloproteinase-l (TIMP-1) production in these cells [Wang, M.; Steams, M. E. Characterization of a novel TIMP-1 enhancer element. J. Biol. Chem., submitted.]. In this paper, we report that IL-10 (20-40 ng) can inhibit the invasion stimulatory effects of ISF (30-60 ng) on PC-3 ML cells. ''Checkerboard analysis'' with modified Boyden chambers (precoated with 10 and 100 mu g collagen IV) shows that IL-10 inhibits the stimulatory effects of ISF on both cell motility and chemoinvasion processes. In support of these data, exogenously supplied TIMP-1 (10 mu g/ml) and collagenase antibodies (1:200 dilution) both completely blocked invasion. Quantitative ELISAs comparing the molar ratios of TIMP-1:MMP-2 and TIMP-2:MMP-2 further demonstrate that IL-10 (10-40 ng) preferentially activates TIMP-1 secretion to increase the molar ratio of TIMP-1:MMP-2 in the presence of increasing amounts of ISF (0-60 ng). IL-10 did not elevate TIMP-2 secretion or influence the molar ratio of TIMP-2:MMP-2. The data demonstrate that IL-10 upregulation of TIMP-1 expression blocks the invasive activity of metastatic PC-3 ML cells in collagen IV gels.