Wall, M., Poortinga, G., Stanley, K. L., Lindemann, R. K., Bots, M., Chan, C. J., Bywater, M. J., Kinross, K. M., Astle, M. V., Waldeck, K., Hannan, K. M., Shortt, J., Smyth, M. J., Lowe, S. W., Hannan, R. D., Pearson, R. B., Johnstone, R. W., McArthur, G. A. (January 2013) The mTORC1 inhibitor everolimus prevents and treats Eμ-Myc lymphoma by restoring oncogene-induced senescence. Cancer Discovery, 3 (1). pp. 82-95. ISSN 21598274
Abstract
MYC deregulation is common in human cancer. IG-MYC translocations that are modeled in Eμ-Myc mice occur in almost all cases of Burkitt lymphoma as well as in other B-cell lymphoproliferative disorders. Deregulated expression of MYC results in increased mTOR complex 1 (mTORC1) signaling. As tumors with mTORC1 activation are sensitive to mTORC1 inhibition, we used everolimus, a potent and specific mTORC1 inhibitor, to test the requirement for mTORC1 in the initiation and maintenance of Eμ-Myc lymphoma. Everolimus selectively cleared premalignant B cells from the bone marrow and spleen, restored a normal pattern of B-cell differentiation, and strongly protected against lymphoma development. Established Eμ-Myc lymphoma also regressed after everolimus therapy. Therapeutic response correlated with a cellular senescence phenotype and induction of p53 activity. Therefore, mTORC1-dependent evasion of senescence is critical for cellular transformation and tumor maintenance by MYC in B lymphocytes. SIGNIFICANCE: This work provides novel insights into the requirements for MYC-induced oncogenesis by showing that mTORC1 activity is necessary to bypass senescence during transformation of B lymphocytes. Furthermore, tumor eradication through senescence elicited by targeted inhibition of mTORC1 identifies a previously uncharacterized mechanism responsible for significant anticancer activity of rapamycin analogues and serves as proof-of-concept that senescence can be harnessed for therapeutic benefit
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