PIK3CA and CCM mutations fuel cavernomas through a cancer-like mechanism

Aileen A. Ren, Daniel A. Snellings, Yourong S. Su, Courtney C. Hong, Marco Castro, Alan T. Tang, Matthew R. Detter, Nicholas Hobson, Romuald Girard, Sharbel Romanos, Rhonda Lightle, Thomas Moore, Robert Shenkar, Christian Benavides, M. Makenzie Beaman, Helge Müller-Fielitz, Mei Chen, Patricia Mericko, Jisheng Yang, Derek C. SungMichael T. Lawton, J. Michael Ruppert, Markus Schwaninger, Jakob Körbelin, Michael Potente, Issam A. Awad, Douglas A. Marchuk, Mark L. Kahn*

*Corresponding author for this work


Vascular malformations are thought to be monogenic disorders that result in dysregulated growth of blood vessels. In the brain, cerebral cavernous malformations (CCMs) arise owing to inactivation of the endothelial CCM protein complex, which is required to dampen the activity of the kinase MEKK31–4. Environmental factors can explain differences in the natural history of CCMs between individuals5, but why single CCMs often exhibit sudden, rapid growth, culminating in strokes or seizures, is unknown. Here we show that growth of CCMs requires increased signalling through the phosphatidylinositol-3-kinase (PI3K)–mTOR pathway as well as loss of function of the CCM complex. We identify somatic gain-of-function mutations in PIK3CA and loss-of-function mutations in the CCM complex in the same cells in a majority of human CCMs. Using mouse models, we show that growth of CCMs requires both PI3K gain of function and CCM loss of function in endothelial cells, and that both CCM loss of function and increased expression of the transcription factor KLF4 (a downstream effector of MEKK3) augment mTOR signalling in endothelial cells. Consistent with these findings, the mTORC1 inhibitor rapamycin effectively blocks the formation of CCMs in mouse models. We establish a three-hit mechanism analogous to cancer, in which aggressive vascular malformations arise through the loss of vascular ‘suppressor genes’ that constrain vessel growth and gain of a vascular ‘oncogene’ that stimulates excess vessel growth. These findings suggest that aggressive CCMs could be treated using clinically approved mTORC1 inhibitors.

Original languageEnglish
Issue number7862
Pages (from-to)271-276
Number of pages6
Publication statusPublished - 10.06.2021

Research Areas and Centers

  • Academic Focus: Center for Brain, Behavior and Metabolism (CBBM)


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