Neuroblastoma cell lines showing smooth muscle cell phenotypes

Neuroblastoma is a tumor that is derived from the neural crest, Recent stud ies demonstrated that several human neuroblastoma cell lines exhibit at lea st three morphologic types: neuroblastic (N)-type, substrate-adhesive (S)-t ype and intermediate (I)-type cells. However, the origin of the S-type cell s has not been clearly identified. In this study, the expressions of smooth muscle-specific proteins (desmin, a-smooth muscle actin, basic calponin an d the smooth muscle myosin heavy-chain isoforms of SM1 and SM2) in three pa rent and four cloned neuroblastoma cell lines, composed of S-type cells, we re examined by indirect immunofluorescence, Western blot and/or by reverse transcription-polymerase chain reaction (RT-PCR). Desmin was found in two o f the seven cell lines, and ct-smooth muscle actin and basic calponin were detected in all of seven of the cell lines. In three parent cell lines and one cloned cell line com posed of N-type cells, none of three smooth muscle -specific proteins were detected. In smooth muscle myosin heavy-chain isofo rms, SMI was detected in two parent cell lines composed of S-type cells (MP -N-MS and KP-N-YS) by immunofluorescence, Western blot and/or by RT-PCR, wh ereas the SM2 isoform was detected in one parent cell line (MP-N-MS) by RT- PCR. These findings indicate that S-type cells have either the immature or mature smooth muscle cell phenotype, and neural crest cells very likely hav e the ability of to differentiate into smooth muscle cells in the human sys tem.