Date of Award
Doctor of Philosophy (PhD)
Next-generation sequencing technology has revolutionized cancer biology by accelerating the unbiased discovery of mutations across human cancers 1-4. Despite this advance, it remains unknown whether there exist mutations that function specifically to drive steps in the metastatic cascade independent from, or perhaps even to the detriment of, tumor initiation and growth 5. The development and implementation of a discovery framework that integrates next-generation RNA-sequencing with in vivo selection, has identified recurrent non-synonymous amino acid mutations that are enriched in metastatic breast cancer cells and predicted to significantly alter protein function. The pro-metastatic role of one of these mutations—a nonsense alteration that yields a truncated pannexin-1 (PANX1 1-89) plasma membrane megachannel subunit—was functionally characterized. PANX1 1-89 forms a multimeric complex with wild-type PANX1 at the plasma membrane and augments PANX1 channel activity to promote cancer cell survival soon after cells enter the microvasculature of metastatic target organs, where they become physically deformed within vessels. Enhanced ATP release from PANX1 channels, which are activated during membrane stretch, acts as a cell autonomous survival signal during lethal cellular deformation. Functional characterization of additional nonsense and missense PANX1 5 mutations detected in epithelial cancers of the colon, lung, and prostate reveals that these mutations also enhance PANX1-mediated ATP release. One such truncating colorectal cancer variant is also shown to promote survival during cellular deformation as well as in vivo intravascular survival, dissemination and metastatic liver colonization by colon cancer cells. Finally, pharmacological treatment of mice with a PANX1 inhibitor suppresses breast cancer metastasis to the lungs, implicating PANX1 as a therapeutic target in cancer. These findings reveal that mutational augmentation of PANX1 channel activity during mechanical trauma enables cancer cells to overcome a major metastasis suppressive barrier—cell death in the microvasculature.
Furlow, Paul William, "Mutations in a Mechanosensitive Channel Enable Intravascular Metaststic Cell Survival" (2014). Student Theses and Dissertations. 264.