Effects of membrane labilising agents and hyperthermia on the activation of lysosomal enzymes in cultured cells.

Abstract A study has been made of the effect of hydrocortisone, filipin, retinol and synthetic retinoids alone and in combination with hyperthermia on lysosomal enzyme activation in Hela cells using quantitative cytochemical methods. Lysosomal enzyme activity has been related to cell survival. Hydrocortisone, filipin and retinol caused an increase in lysosomal acid phosphatase activity when cells were incubated at 37°C. Incubation of cells at 43°C for 60 min caused a marked increase in lysosomal enzyme activity and addition of hydrocortisone, filipin or retinol strongly enhanced the enzyme activation. It is concluded that the effects of hyperthermia may be potentiated by compounds which interact with membranes and increased cell death may result from labilisation of the lysosomal membranes. The synthetic retinoids, Ro 10-9359 and Ro 10-1670 were much less effective than retinol at 37° or at 43°. Incubation of cells with retinol at 37° caused a reduction in cell survival and this was further reduced if the cells were incubated at 43°. The synthetic retinoids were less effective.