Figure 4.

 Down‐regulation of αv integrin is required for rapamycin‐mediated suppression of B16 metastasis. (a) Construction of αv integrin‐overexpressing B16 cell line. αv Integrin‐expressing plasmid was transfected to B16 cells. The stably transfected cells were used to analyze αv integrin expression by Western blotting. (b) Rapamycin did not inhibit the exogenous expression of αv integrin. (c) Overexpression of αv integrin partly reversed the suppression of rapamycin in lung metastasis. αv‐Overexpressing or mock B16 cells, treated with rapamycin, were injected into mice via the tail vein. Twenty‐one days later, the mice were sacrificed and the lung tumor nodules were counted. (d) Comparison of the effect on B16 cell metastasis among rapamycin, CH50, and αv integrin antagonist. B16 cells were treated with rapamycin (0.5 μg/mL), CH50 (10 μg/mL), or high‐dose CH50 (25 μg/mL); or αv integrin antagonist (10 μg/mL) or high dose (25 μg/mL) for 24 h. Then the cells were injected to the mice. Twenty‐one days later, the mice were sacrificed and the lung tumor nodules were counted.