Photodynamic induced cytotoxicity by Victoria blue BO (VB-BO), merocyanine 540 (MC540), Nile blue A (NB) and 4-tetrasulfonatophenyl-porphyrin (4-TSPP) has been studied on two human leukemic cell lines: K-562 and TF-1. Cells were incubated with dyes and irradiated with different doses of white light. Cell survival was assessed by propidium iodide (PI) staining using flow cytometry analysis. Concentrations of 5 x 10(-8) M VB-BO were found to kill 75% of cells, and a concentration of 1 x 10(-7) M induced more than 99% of cell killing. To obtain the same cytotoxic level, the presence of 2.6 x 10(-5) M of MC540 during irradiation was needed. Under the conditions used, NB was ineffective as a photosensitizer, although uptake studies showed that this dye was taken by the cells in much greater amounts than any other studied dye. Cell cycle distribution of TF-1 cells, surviving MC540 or VB-BO photosensitization has been studied by flow cytometry analysis after staining with Hoechst 33342 and PI. It was found that cells in G1 phase were slightly more resistant toward MC540- and VB-BO-mediated photosensitization than cells in other phases of the cell cycle.
The effects of variations in the concentrations of L-cystine (Cys), L-methionine (Met), and L-glutamine (Glu) on the establishment of melanocyte cell lines obtained from a primary tumor and its metastasis in the same patient were studied. The special role of Glu was also studied in 4 lymph node metastases from other patients. Differentiation in vitro was dependent on the culture conditions, as assessed by morphologic and biochemical studies. Karyologic expression, doubling time, cloning efficiency, and tumorigenicity in nude BALB/c mice varied widely among the cell lines. Cys was an indispensable amino acid and Glu was not. Met and Glu were implicated in melanogenesis. From these observations arose the question of the accuracy of comparative results, concerning differentiation and tumorigenicity, that had been collected for cell lines obtained under different culture conditions.
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