Phenotypic and genotypic diversity of human neuroblastoma studied in threeIGR cell line models derived from bone marrow metastases

Metastatic stage TV neuroblastoma tumors, as well as cell lines derived fro m them, are highly malignant and rapidly fatal. To determine whether malign ant potential of there cells might be influenced by stromal tissue at sites frequently involved in metastasis, we initiated primary cultures from bone marrow of three patients (331, 337, and 91) with stage IV neuroblastoma. A ll three explants contained two distinct cell populations malignant neurobl asts (Nb-type) and substrate adherent stromal-like (Str-type) cells. The ce ll types were separated at the first passage and studied by cytogenetic, mo lecular and immunocytochemical methods. Karyotypic analyses after 3-6 passa ges in vitro revealed the presence of unique chromosomal abnormalities in N b-type cells of all three lines: (1) der(1)t(1;7) (p32;q11) and der(5)t(5;1 7)(q35;q21) in pseudodiploid IGR-N-331 neuroblasts; (2) der(1)t(1;17)(p35;q 21-22)x2 and der(7)t(7;7)(p21;q21) in IGR-N-337 hyperdiploid neuroblasts; a nd (3) more than six rearranged chromosomes in two related subpopulations o f hypodiploid IGR-N-91 neuroblasts. Neuroblastic cells from all three tumor s amplified MYCN 25- to 50-fold (with amplified genes visible as dmin or, i n one IGR-N-91 subline, as an hsr(14)[q32]) and expressed N-CAM. Str-type c ells from tumors 331 and 337 had a normal diploid karyotype, did not expres s either N-CAM or S-100, and are probably normal bone marrow fibroblasts. B y contrast, S-100 negative Str-type IGR-N-91 cells were hypodiploid and sha red at least two unbalanced translocations, der(4)t(1;4)(q12;p15) and der(2 )t(2;10;17)(p14;q11;q22), with neuroblastic counterparts, indicating that " stromal" cells and malignant neuroblasts had a common tumor cell origin. Th us, the Str-type cells of IGR-N-91 are examples of S-type phenotypic varian ts frequently described for long-term human neuroblastoma cell lines in vit ro, but not previously observed in vivo, (C) Elsevier Science Inc., 1999. A ll rights reserved.