Establishment of a cell line from a malignant rhabdoid tumor of the liver lacking the function of two tumor suppressor genes, hSNF5/INI1 and p16.

Malignant rhabdoid tumors (MRT) of the liver are rare. A few liver MRT cell lines have been established but none has been characterized in detail. Here we describe a new MRT cell line from the liver, which is designated MP-MRT-AN, and describe it in detail. Immunohistochemical assays detected the expression of vimentin and cytokeratin but they were negative for neurofilament, desmin, alpha-smooth muscle actin, alpha-sarcomeric actin, and smooth muscle myosin heavy chains SM1 and SM2. RT-PCR assays revealed that this cell line did not express smooth muscle myosin heavy chain isoforms or MyoD1. No aberration was identified in 22q by G-banded analysis; however, the hSNF5/INI1 gene, a suppressor gene of MRT that maps to 22q11.2, was homozygously deleted from exons 1 to 5 in this cell line. Furthermore, the expression of another tumor suppressor gene, p16 (CDKN2A), was not detected by RT-PCR. This raises the possibility that the aggressive phenotype of malignant rhabdoid tumors is caused by the loss of two or more tumor suppressor genes.