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Pawlikowski JS , McBryan T , van Tuyn J , Drotar ME , Hewitt RN , Maier AB , King A , Blyth K , Wu H , Adams PD
Wnt signaling potentiates nevogenesis
Proceedings of the National Academy of Sciences of the United States of America. 2013 Oct;110(40) :16009-16014
PMID: WOS:000325105500048    PMCID: PMC 3791768   
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Cellular senescence is a stable proliferation arrest associated with an altered secretory pathway (senescence-associated secretory phenotype). Cellular senescence is also a tumor suppressor mechanism, to which both proliferation arrest and senescence-associated secretory phenotype are thought to contribute. The melanocytes within benign human nevi are a paradigm for tumor-suppressive senescent cells in a premalignant neoplasm. Here a comparison of proliferating and senescent melanocytes and melanoma cell lines by RNA sequencing emphasizes the importance of senescenceassociated proliferation arrest in suppression of transformation. Previous studies showed that activation of the Wnt signaling pathway can delay or bypass senescence. Consistent with this, we present evidence that repression of Wnt signaling contributes to melanocyte senescence in vitro. Surprisingly, Wnt signaling is active in many senescent human melanocytes in nevi, and this is linked to histological indicators of higher proliferative andmalignant potential. In a mouse, activated Wnt signaling delays senescenceassociated proliferation arrest to expand the population of senescent oncogene-expressing melanocytes. These results suggest that Wnt signaling can potentiate nevogenesis in vivo by delaying senescence. Further, we suggest that activated Wnt signaling in human nevi undermines senescence-mediated tumor suppression and enhances the probability of malignancy.
Pawlikowski, Jeff S. McBryan, Tony van Tuyn, John Drotar, Mark E. Hewitt, Rachael N. Maier, Andrea B. King, Ayala Blyth, Karen Wu, Hong Adams, Peter D.