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Oncogene. 2009 Jan 15;28(2):306-12. doi: 10.1038/onc.2008.384. Epub 2008 Oct 13.

PI(3) kinase is associated with a mechanism of immunoresistance in breast and prostate cancer.

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Department of Neurological Surgery, University of California San Francisco, San Francisco, CA 94143, USA.


Immune escape describes a critical event whereby tumor cells adopt an immunoresistant phenotype to escape adaptive surveillance. We show that expression of a pivotal negative regulator of T-cell function, B7-H1, correlates with PI(3) kinase activation in breast and prostate cancer patients. B7-H1-mediated immunoresistance can be attenuated by inhibitors of the PI(3) kinase pathway, and is dependent on S6K1-mediated translational regulation of B7-H1 protein. Breast and prostate carcinoma cells with activated PI(3) kinase lose the immunoresistant phenotype after treatment with B7-H1 siRNA. Conversely, breast and prostate carcinoma cells with minimal PI(3) kinase activation adopt an immunoresistant phenotype when engineered to overexpress B7-H1 protein. These observations describe a mechanism for immune escape from tumor dormancy in humans that relates to oncogenesis.

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