Multiple inflammatory cytokine‐productive ThyL‐6 cell line established from a patient with thymic carcinoma

Thymic epithelial cells can produce many kinds of cytokines, and interleukin (IL)‐6‐producing thymic carcinoma cases have been reported. However, a cytokine‐producing human thymic tumor cell line has not previously been established. In this paper, we report a novel, multiple inflammatory cytokine‐productive cell line that was established from a patient with thymic carcinoma. This cell line, designated ThyL‐6, positively expressed epithelial membrane antigen, cytokeratins, vimentin intermediate filament and CD5, although hematological markers were not present in the cells. Cytokine antibody array analysis showed that the cells secreted several cytokines including IL‐1α, IL‐6, IL‐8, RANTES, soluble TNFα‐receptor 1, VEGF and CTLA into the culture medium. The addition of ThyL‐6‐cultured supernatant supported the growth of human myeloma ILKM‐3 cells, which require the presence of IL‐6 in the culture medium for the maintenance of cell growth, suggesting that the secreted IL‐6 from ThyL‐6 cells was biologically active. Chromosome analysis demonstrated that ThyL‐6 cells had complex karyotype anomalies, including der(16)t(1;16); the latter has been recognized in thymic squamous cell carcinoma and thymic sarcomatoid carcinoma cases, as well as in several other kinds of malignancies. Heterotransplantation of the cells into nude mice showed tumorigenesis with neutrophil infiltration and liquefactive necrosis. These findings suggest that ThyL‐6 cells will provide us with a new experimental tool for investigating not only the pathogenesis, biological behavior, chromo‐somal analysis and therapeutic reagents of human thymic carcinoma, but also for studying cytokine–chemokine network systems. ( Cancer Sci 2008; 99: 1778–1784)