Transcription factor CCAAT/enhancer-binding protein alpha and critical circadian clock downstream target gene PER2 are highly deregulated in diffuse large B-cell lymphoma

AbstractDisturbances of circadian rhythms and mammalian clock genes have been implicated in the etiologies of many chronic illnesses, including cancer. We show that transcription factor CCAAT/enhancer-binding protein alpha (C/EBPalpha)-regulated PER2 activation is a potential tumor suppressor pathway in diffuse large B-cell lymphoma (DLBCL), one of the commonest types of mature B-cell lymphoma. Expression analysis of human B-cell lymphoma samples including DLBCL (n = 50), mantle cell (n = 21), follicular (n = 25) and Burkitt (n = 18) lymphoma revealed markedly down-regulated CEBPA and PER2 mRNA levels exclusively in DLBCL samples compared to control lymphatic tissue. We demonstrated direct regulation of the circadian core clock gene PER2 by C/EBPalpha in the pro-B cell line Ba/F3, and forced expression of PER2 resulted in decreased proliferation, G0/G1 cell cycle arrest and increased rates of apoptosis. Interestingly, treatment of human DLBCL cell lines with the histone deacetylase-inhibitor suberoylanili...