The RasGAP Gene, RASAL2, Is a Tumor and Metastasis Suppressor

• RASAL2 is inactivated in breast cancer, and RASAL2 loss is associated with progression
• RASAL2 ablation promotes tumor growth, progression, and metastasis in cancer models
• RASAL2 may play a particularly important role in luminal B breast cancer
• RASAL2 loss may promote the progression of other cancers

SummaryRAS genes are commonly mutated in cancer; however, RAS mutations are rare in breast cancer, despite frequent hyperactivation of Ras and ERK. Here, we report that the RasGAP gene, RASAL2, functions as a tumor and metastasis suppressor. RASAL2 is mutated or suppressed in human breast cancer, and RASAL2 ablation promotes tumor growth, progression, and metastasis in mouse models. In human breast cancer, RASAL2 loss is associated with metastatic disease; low RASAL2 levels correlate with recurrence of luminal B tumors; and RASAL2 ablation promotes metastasis of luminal mouse tumors. Additional data reveal a broader role for RASAL2 inactivation in other tumor types. These studies highlight the expanding role of RasGAPs and reveal an alternative mechanism of activating Ras in cancer.