Chromosomal abnormalities of a new nasopharyngeal carcinoma cell line (NPC-BM1) derived from a bone marrow metastatic lesion

An epithelial cell line, NPC-BM1, was established from a bone marrow biopsy of a female Taiwanese patient with nasopharyngeal carcinoma (NPC). Histopathology of the bone marrow biopsy and xenografts grown in severe combined immunodeficiency mice showed that the tumor was a non-keratinizing, poorly differentiated carcinoma. NPC-BM1 cells grown as monolayers had a doubling time of 28.5 hours. Chromosome analysis showed that NPC-BM1 had the following features: 1) hypotetraploidy with a modal chromosome number of 87 (84-90); 2) numerically and structurally normal chromosomes 18; 3) numerical abnormalities without apparent structural alterations on chromosomes 14, 16, 17, 19, and 20; 4) ten structural abnormalities, t(1;9)(p11;q11), t(3;?;4)(p13;?;q13), add(4p),del(6p), i(18)(q10),der(?)t(?;12),(?;p11),add(21)(p11), del(X)(q24), add(X)(q22), and marker 1 (M1), in all metaphases examined, which were found to be present in two to five cell lines from primary NPC tumors reported previously; and 5) four other abnormalities, t(2;?;2)(p11.2;?;q21),t(11;22)(q11;q11),i(22)(q10), and marker 2 (M2), unique to this metastatic cell line. To the best of our knowledge, NPC-BM1 is the first NPC cell line derived from a distant metastatic site. Further evaluation of this cell line and additional metastatic NPC cell lines as well as primary NPC cell lines with respect to relations between the timing, karyotypic anomalies, and immunobiological characteristics in NPC progression and metastasis is warranted.