Basic studies on gene therapy of human malignant melanoma by use of the human interferon β gene entrapped in cationic multilamellar liposomes.: 1.: Morphology and growth rate of six melanoma cell lines used in transfection experiments with the human interferon β gene

Six cell lines of human malignant melanoma: A375, A375.2, 6361, HMV-1, MM8.1 and WM115 were seeded at densities of 1x10(4) cells/ml, 2x10(4) cells/ml or 3x10(4) cells/ml of RPMI medium supplemented with 10% fetal calf serum and antibiotics in a humidified atmosfere of 5% CO2 at 37degreesC. A375 cells were also grown in Dulbecco's minimum Eagle's medium (DMEM medium). The morphology was studied by phase contrast light microscopy. At 4 days after seeding the colonies of A375 cells and HMV-1 cells were oval-shaped, the cells were polyhedrical and were making contact with each other regularly. The remaining cells were scattered, more elongated, and made contact randomly. 6361 cells and MM8.1 cells tended to form superposed layers before 100% confluency was achieved. There were great differences in the growth rate and doubling time of melanoma cells. The doubling time in day 1 was short (around 6-12 h) in the case of A375, 6361 and HMV-1 cells, longer (around 18h) in the case of MM8.1 cells and very long (ranging between 26 and 89 h) for A375.2 and WM115 cells. There were also differences in the doubling time of cells as a function of the cell density at seeding. On the other hand, except for MM8.1 cells, there were differences between the doubling time in day 2 compared to day 1.