Stimulation of lysosomal enzyme secretion by growth factors.
Levels of extracellular lysosomal enzymes are relatively high in tumors and especially so at their periphery. By degrading the intercellular matrix, these and other nonlysosomal enzymes could facilitate invasion and metastasis by tumor cells. Using a rapid assay, we have shown that cells transformed by a variety of agents can be stimulated in culture by several growth factors to secrete lysosomal enzymes. These factors have little or no stimulatory activity on their nontransformed counterparts. The basal rate of secretion of N-acetylglucosaminidase (NAGA) and the efficiency of the stimulus are greater in transformed cells in log phase of growth. These observations suggest that altered or increased responsiveness to paracrine and autocrine growth factors not only may be responsible for the persistent division of malignant cells but also may promote their invasiveness.
Warren
L
L
Wistar Institute of Anatomy and Biology, Philadelphia, Pennsylvania 19104.
D000118:Acetylglucosaminidase / Q000378:metabolism*; D000818:Animals; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D004815:Epidermal Growth Factor / Q000502:physiology; D005346:Fibroblast Growth Factors / Q000502:physiology; D006133:Growth Substances / Q000502:physiology*; D006596:Hexosaminidases / Q000378:metabolism*; D007700:Kinetics; D008247:Lysosomes / Q000201:enzymology* / Q000378:metabolism; D013917:Thrombin / Q000502:physiology; D015291:Transforming Growth Factors / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology
D006133:Growth Substances; D014409:Tumor Necrosis Factor-alpha; D005346:Fibroblast Growth Factors; D004815:Epidermal Growth Factor; D015291:Transforming Growth Factors; D006596:Hexosaminidases; D000118:Acetylglucosaminidase; D013917:Thrombin