Effects of retinoic acid on proliferation, apoptosis, cytotoxicity, migration, and invasion of neuroblastoma cells

Background. Because of the known property of less aggressiveness of differentiated cells compared to immatured cells all attempts are made to elucidate whether differentiation inducers possibly could be applied for neuroblastoma therapy. We are interested in examining the influence of retinoic acid (RA) on proliferation, apoptosis, cytotoxicity, migration, and invasion in dependence of the differentiation of neuroblastoma cells classified into N-type (SK-N-FI, SH-SY5Y), I-type (SK-PN-DW), and S-type (SK-N-LO, SK-N-MC) cells. Procedure. Neuroblastoma cells were exposed to 10(-5)MRA and 200 ng/ml camptothecin (CAM) (control substance for apoptosis). Proliferation, apoptosis, and cytotoxicity were quantified by photometric assays. The influence on migration and invasion of neuroblastoma cells was examined by a scratch-test and by the measurement of the invasion through matrigel coated chamber inserts. Results. In general, RA treatment induced proliferation inhibition predominantly in the cell lines SK-PN-DW (16%, P < 0.05) and SK-N-MC (8%, (P < 0.001), respectively. In the N-type cell lines SK-N-FI (P > 0.05) and SH-SY5Y (P < 0.001) no proliferation inhibition was determined conforming with no detection of apoptosis. CAM confirmed its capability to induce apoptosis in the cell lines SH-SY5Y (43.6%, P < 0.05), SK-PN-DW (54.8%, P > 0.05), and SK-N-MC (28.9%, P < 0.001) except for SK-N-FI with only 9.3% (P > 0.05), but after 24 hr of treatment. Minor signs of restricted migration were observed, while RA treatment reduced significantly the invasion rate through Matrigel of SK-N-FI to 13.3% (P < 0.01), SH-SY5Y to 19.2% (P < 0.05), SK-N-MC to 27.8% (P < 0.05), and SK-N-LO to 17.7% (P < 0.01). Conclusions. It is demonstrated that RA treatment can interfere with cell growth and in invasion by inducing neuronal differentiation in N-type and apoptosis in S-type neuroblastoma cell lines. (C) 2003 Wiley-Liss, Inc.