Cheng Chi Lee

Cheng Chi Lee made the discovery that the circadian genes PER1 and PER2 function as tumor suppressors, demonstrating that PER2 mutation in mice leads to increased susceptibility to radiation-induced lymphoma and other cancers. His research showed that PER genes regulate DNA damage response pathways including ATM, Chk2, and p53, directly linking the circadian clock to genome integrity maintenance. He established that epigenetic silencing of PER genes through promoter methylation is a frequent event in human cancers including breast, colorectal, and lung cancer. His work defined circadian genes as bona fide tumor suppressors whose inactivation contributes to cancer development.