Fig 2. Xenograft spontaneous metastasis model of human melanoma cells with high L1CAM expression (MeWo) in scid mice.

L1CAM knockdown reduces metastasis by more than 80%. Statistics: All numbers n represent the total number of individual samples of the respective experiment. Survival of mice was analyzed using a linear model which was moreover adjusted for the type of death (ulcerated vs. not ulcerated). Tumor weight was analyzed in an analogous model. Number of metastases was analyzed and evaluated/quantified using a negative binomial regression which was adjusted for survival time and tumor weight and included furthermore CTCs as variable. CTCs as outcome variable were logarithmized and analyzed using a linear model, which was adjusted for survival time and tumor weight. If PGroup X Line is below 0.05 (i.e. if L1CAM knockdown displays different effects for the two cell lines), a separate PLuc vs. L1kd is given for each cell line. Animals’ survival after subcutaneous injection of 10⁶ melanoma cells: L1CAM knockdown did not significantly change the animals’ survival time (A). The weight of the MeWo L1 kd tumors was not significantly different from the MeWo Luc control tumors, the weight of the MV3 L1 kd tumors was significantly higher than the tumor weight of the MV3 Luc control tumors (B). The number of lung metastases was significantly lower (reduced 7.26 fold) in the L1 kd than in the Luc control groups both for MeWo and MV3 (C). The numbers of circulating tumor cells (CTC) in the animals’ blood were not significantly altered by L1CAM knockdown both for MeWo and for MV3 (D).