title: Proliferating cells of human basal cell carcinoma are located on the periphery of tumor nodules.
abstract: Study of the growth characteristics of basal cell carcinoma (BCC), a relatively well-organized, slow-growing skin cancer, has been limited because of the lack of methods for propagation of the tumor off the human host. We have used newly developed techniques for transplantation and propagation of BCC on athymic mice to study [3H]thymidine incorporation by nodular BCC. In human BCCs labeled in vitro immediately after removal from the mice and in vivo on the mice, [3H]thymidine during a 4-h pulse was incorporated primarily by cells on the periphery of tumor nodules (labeling indices 6-24%) rather than by the cells more central in tumor nodules (labeling indices 0-2%). Similar results were also seen when samples of tumor freshly removed from patients were labeled in vitro. We conclude that the dividing cells within nodular BCC are primarily the cells at the edges of tumor nodules and that this characteristic is related to the slow, progressive, invasive growth of BCC.
mesh_terms: D000818:Animals; D001345:Autoradiography; D002280:Basal Cell Carcinoma / Q000473:pathology*; D002455:Cell Division; D004273:DNA, Neoplasm / Q000096:biosynthesis; D006801:Humans; D051379:Mice
chemical_list: D004273:DNA, Neoplasm