The "Mutated in Colorectal Cancer" Protein Is a Novel Target of the UV-Induced DNA Damage Checkpoint

• Published in: Genes & cancer 2010-09, Vol.1 (9), p.917-926
• Main Authors: Pangon, Laurent, Sigglekow, Nicholas D, Larance, Mark, Al-Sohaily, Sam, Mladenova, Dessislava N, Selinger, Christina I, Musgrove, Elizabeth A, Kohonen-Corish, Maija R J
• Format: Article
• Language: English
• Subjects: Original
• ISSN: 1947-6019; 1947-6027
• DOI: 10.1177/1947601910388937

MCC is a potential tumor suppressor gene, which is silenced by promoter hypermethylation in a subset of colorectal cancers. However, its functions have remained poorly understood. In the present study, we describe a novel function of MCC in the DNA damage response. Several novel phosphorylation sites were identified by mass spectrometry, including 2 highly conserved ATM/ATR consensus sites at serine 118 and serine 120. In addition, exposure to ultraviolet radiation (UV), but not phleomycin, caused PI3K-dependent phosphorylation of MCC and its nuclear localization. Re-expression of MCC in HCT15 colorectal cancer cells led to a G2/M arrest, and MCC knockdown impaired the induction of a G2/M arrest following UV radiation. Finally, mutation of S118/120 to alanine did not affect MCC nuclear shuttling following UV but did impair MCC G2/M checkpoint activity. Thus, these results suggest that MCC is a novel target of the DNA damage checkpoint and that MCC is required for the complete cell cycle arrest in the G2/M phase in response to UV.