Abstract 287: A nuclear cAMP microdomain suppresses tumor growth by Hippo Pathway inactivation

Cyclic AMP can both promote and suppress tumor growth; however, how this single second messenger can simultaneously have such disparate effects on cancer remains largely undefined. It is well appreciated that cAMP does not diffuse within a cell but is made in microdomains, which consist of a unique adenylyl cyclase, one or more phosphodiesterases, and cAMP effector proteins, but the role of specific cAMP microdomains in cancer is unclear. Examination of human tissue biopsies revealed that the nuclear cAMP microdomain, defined by the soluble adenylyl cyclase (sAC), is upregulated early in tumorigenesis, but is lost with melanoma invasion and metastasis. Further, we showed that loss of sAC led to the transformation of melanocytes and reintroduction of sAC, only into the nucleus, was sufficient to block tumorigenesis in vitro and in mice. Neither mitochondrial, nor cytoplasmic cAMP microdomains affected tumor cell growth. Activation of nuclear sAC led to significant changes in chromatin accessibility suggesting that this cAMP microdomain regulates numerous transcription factors. Specifically, activation of nuclear sAC led to reduced chromatin accessibility for the TEAD and SMAD family of transcription factors, the key effectors of the Hippo Pathway. Consistent with those data, nuclear sAC suppressed TEAD-dependent pro-cancer gene expression profiles (e.g., MYC) by inhibiting YAP, one of the main oncoproteins in this signaling cascade. Moreover, we showed that nuclear cAMP evokes the same YAP-dependent inhibition of the Hippo Pathway in a variety of cancers, suggesting tumor suppression by nuclear sAC is not limited to melanoma. These studies reveal that a cAMP microdomain wholly contained within the nucleus is a pivotal a tumor suppressor that acts via Hippo Pathway inactivation. Citation Format: Marek M. Drozdz, Ashley Doane, Garrett Desman, Jenny Wang, Michael Reilly, Kelsey Aguirre, Elsbeth Kane, Jedd Wolchok, Taha Merghoub, Olivier Elemento, Elena Piskounova, Jonathan Zippin. A nuclear cAMP microdomain suppresses tumor growth by Hippo Pathway inactivation [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 287.