PROTOPORPHYRIN-IX ACCUMULATION IN CELLS TREATED WITH 5-AMINOLEVULINICACID - DEPENDENCE ON CELL-DENSITY, CELL-SIZE AND CELL-CYCLE

Human colon adenocarcinoma cells (WiDr) and Chinese hamster lung fibro blasts cells (V79) were incubated with different concentrations of 5-a minolevulinic acid (ALA), and the production of protoporphyrin IX (PpI X) was studied using several techniques. The amount of PpIX produced p er cell increased with increasing ALA concentration according to diffe rent kinetics for the 2 cell lines. For both cell lines a cell density dependency of the PpIX synthesis was observed. For saturating ALA con centrations, 2-3 times more PpIX was produced per cell at a density of 5 X 10(4) than at a density of 5 X 10(3) cells/cm(2). The photosensit ivity of cells appeared to increase even more than the PplX content, i ndicating a cooperative effect in inactivation. The PpIX production ra te increased with cell size and was about 1.9 times higher for cells i n the G(2) + M phase than for cells in the G(1) phase of the cell cycl e. Neither cell size nor cell cycle distribution were significantly de pendent on cell density. (C) 1998 Wiley-Liss, Inc.