Merkel cell carcinoma: In vitro and in vivo characteristics of a new cell line

Background : Few studies exist that describe Merkel cell carcinoma (MCC) growth characteristics in vitro, in vivo, or both. Objective : Our purpose was to evaluate the pathologic features of MCC implanted into athymic mice and to determine cytogenetic abnormalities in the established cell line. Methods : Tumor tissues from a patient with MCC were grown in culture. Cultured cells were karyotyped and inoculated subcutaneously into athymic mice. Nude mouse tumors were reimplanted into other athymic mice. Tissues from the primary skin tumor and the nude mouse tumor were processed for light and electron microscopy and immunocytochemistry. Results : The cell line showed a doubling time of 64.8 hours. Xenografts of 4 × 10 6 cells produced tumors in athymic mice with a doubling time of 16.1 days. The nude mouse tumors showed pathologic features similar to those of the primary skin tumor. Cytogenetic studies showed a t(1;17) (p36;q21) translocation in 100% of the cells. Conclusion : MCC implanted into athymic mice retained the pathologic features of the primary skin tumor and behaved aggressively. The t(l;17) (p36;q21) translocation may be a marker of an aggressive phenotype.