Malignant rhabdoid-tumor cell line showing neural and smooth-muscle-cell phenotypes

Malignant rhabdoid tumor (MRT) is a rare and extremely aggressive malignant tumor in childhood. In this study, an MRT cell line, designated KP-MRT-NS, was established from the ascitic fluid taken from an Ii-month-old girl, wh ose tumor had originated from the left kidney. Ultrastructural findings dem onstrated the typical aggregation of whorls of intermediate filaments. Chro mosome constitution was described as 46, XX, add(10)(q26)[17]/46, idem, dis (1;2)(q22; q31)[3] based on ISCN (1995) and a del (22)(q11.2) was not found in this cell line. The origin of MRT is controversial, various cellular or igins having been proposed because of the phenotypic diversity of MRT, Ther efore, in this study, to clarify the origin of MRT, the expressions of cyto plasmic proteins including smooth-muscle-specific proteins (alpha-smooth-mu scle actin, basic calponin, smooth-muscle-myosin-heavy-chain isoforms of SM 1 and SM2) in the primary-MRT tissue and cell line were analyzed. In the pr imary-tumor tissue, the expressions of neurofilament, vimentin and cr-smoot h-muscle actin were demonstrated by indirect immunofluorescence. In the KP- MRT-NS cell line, the expression of neurofilament, alpha-smooth-muscle acti n, basic calponin and smooth-muscle myosin heavy chain of SM I and SM2 isof orms was revealed by immunofluorescence, Western blot and/or reverse transc riptase-polymerase chain reaction (RT-PCR). MyoDI mRNA, determined as a ske letal-muscle-cell lineage marker, was not expressed in the primary-tumor ti ssue or in the KP-MRT-NS cell line. According to our findings, the MRT cell s are of both neural and smooth-muscle cell phenotypes, and support the neu ral-crest origin of MRT, Int. J. Cancer 82:678-686, 1999. (C) 1999 Wiley-Li ss. Inc.