Characterization of an extracellular matrix-degrading protease derived from a highly metastatic tumor cell line

Determination of cell-free interleukin 2 receptor level in the serum of normal animals and of animals bearing IL-2 receptor positive tumours with high or low metastatic capacity

“…We have shown before that ESb cells shed more Fc receptors into the serum than Eb cells (Schirrmacher & Jacobs, 1979) and that the release is mediated via the shedding of extracellular plasma membrane vesicles (Schirrmacher & Barz, 1986). ESb cells shed about three times as many vesicles than Eb cells and these vesicles differ in their chemical and biochemical composition from the original plasma membranes (Barz et al, 1985). It was therefore concluded that the process of plasma membrane exfoliation represents a selective rather than a random process.…”

“…These studies were initiated in order (i) to determine whether soluble IL-2 receptors in the serum of IL-2 receptor positive tumour bearing animals might be a sensitive tumour marker and (ii) to see whether such a marker might correlate with the extent of metastasis and tumour progression. The comparison of high and low metastatic related tumour lines also aimed at the question whether metastatic cells might shed more receptor material than non-metastatic cells, a phenomenon which has been observed before in the same tumour system when analyzing release of Fc receptors (Schirrmacher & Jacobs, 1979) and release of membrane vesicles (Barz et al, 1985;Schirrmacher & Barz, 1986) in tumour-bearing animals. The tumour lines used in this study have previously been shown to express IL-2 receptors although to a different extent (Diamantstein et al, 1985).…”

“…It was therefore concluded that the process of plasma membrane exfoliation represents a selective rather than a random process. It results in the selective release of certain membrane molecules including certain receptors, tumour antigens (Schirrmacher & Barz, 1986) and degradative enzymes (Kramer et al, 1985). An increased release of IL-2 growth factor receptor by metastatic tumour cells could have a selective growth advantage for the tumour cells because these receptors might absorb the growth factor IL-2 which is required for growth and expansion of host T-lymphocytes with anti-tumour activity.…”

“…The spontaneous high metastatic variant ESb is most likely derived from a spontaneous fusion of the parental Tlymphoma Eb with a host macrophage (Larizza et al, 1984). The two lines were found to differ in many cell surface properties including expression of differentiation antigens , of composition of membrane glycoproteins (Schwartz et al, 1984), glycolipids (Murayama et al, 1986) and in the shedding of membrane vesicles (Barz et al, 1985;Schirrmacher & Barz, 1986 (Waller et al, 1986). In vivo, however, the ESb-M line showed greatly decreased overall malignancy (Benke et al, 1987).…”

Activity Patterns of Proteolytic Enzymes – Relationship to Neoplastic Events during Experimental Carcinogenesis and Preliminary Results from Colorectal Tumor Patients

“…According to this observation, the proteases must be restricted in their efficiency. Our hypothesis has to be supplemented: the enzymes are bound to membranes, normal cells are protected by inhibitors, or transformed cells have a lack of receptors involved in the protection of their pericellular structures [19,29,35,45].…”