Figure 1. Human melanomas exhibit intrinsic differences in their metastatic efficiency in NSG mice.

(A) 27 melanomas from 25 patients were transplanted subcutaneously into NSG mice in doses between 1 and 50,000 cells per injection. Mice with subcutaneous tumors were monitored until the tumors grew to 1.4±0.9 cm (mean ± SD) in diameter, 21.8±10.2 weeks after transplantation. Upon necropsy, organs were visually examined for the presence of metastases. “AJCC clinical stage” is the American Joint Committee on Cancer stage of the patient at the time of melanoma removal. “Tumor site” reflects the location of the tumor in the patient. Melanomas 633/634 and 498/499 (boxed) were pairs of tumors obtained from different locations in the same patients at the same time. The metastatic behavior of each melanoma was examined in 2 to 22 independent experiments with 6 to 136 mice that formed subcutaneous tumors per melanoma (see Table S2 for more details). The rate of metastasis (%) is the percentage of mice with subcutaneous tumors that developed macrometastases. (B) Tumors that formed at the injection site as well as macrometastases in mice transplanted with cells from four patients. Metastases were confirmed as melanoma by a dermatopathologist after staining sections with hematoxylin and eosin (H&E) and S-100. Table S1 contains clinical details for each melanoma and patient. Table S2 has details regarding rates of metastasis at different cell doses for each melanoma. Table S3 shows the results for each independent experiment conducted on each melanoma. Table S4 shows the location where macrometastasis was detected for each melanoma.