Autocrine Production and Synergistic Growth-Promoting Activity of Interleukin-6 and Oncostatin M in a New Human Myeloma Cell Line TU-1

Human myeloma cell lines are difficult to establish, and they usually originate from patients with extramedullary disease. We describe a new human myeloma cell line, TU-1, which was established from the bone marrow of a patient without extramedullary myeloma. The myeloma cells were initially maintained in a conditioned medium derived from another well-known myeloma cell line U-266. This conditioned medium contained interleukin-6 (IL-6) and oncostatin M (OSM), and possibly other unknown growth factors as well. In 3 months the TU-1 cell line proliferated autonomously and secreted IL-6 and OSM with a synergistic growth response. As we have previously shown the cell line acquired a p53 mutation in vitro, which may be an important factor causing autonomous proliferation. In patients with multiple myeloma OSM is frequently found in the serum and OSM has been associated with serum IL-6 and progressive disease. Our study demonstrates the close relationship of OSM and IL-6 also in vitro.