CDKN1C/P57 is regulated by the Notch target gene Hes1 and induces senescence in human hepatocellular carcinoma.
CDKN1C/P57 is a cyclin-dependent kinase inhibitor implicated in different human cancers, including hepatocellular carcinoma (HCC); however, little is known regarding the role of CDKN1C/P57 and its regulation in HCC. In this study, we show that the down-regulation of Notch1 and Notch3 in two HCC cell lines resulted in Hes1 down-regulation, CDKN1C/P57 up-regulation, and reduced cell growth. In line with these data, we report that CDKN1C/P57 is a target of transcriptional repression by the Notch effector, Hes1. We found that the up-regulation of CDKN1C/P57 by cDNA transfection decreased tumor growth, as determined by growth curve, flow cytometry analysis, and cyclin D1 down-regulation, without affecting the apoptosis machinery. Indeed, the expression of Bax, Noxa, PUMA, BNIP(3), and cleaved caspase-3 was not affected by CDKN1C/P57 induction. Morphologically CDKN1C/p57-induced HCC cells became flat and lengthened in shape, accumulated the senescence-associated β-galactosidase marker, and increased P16 protein expression. Evaluation of senescence in cells depleted both for Hes1 and CDKN1C/P57 revealed that the senescent state really depends on the accumulation of CDKN1C/p57. Finally, we validated our in vitro results in primary HCCs, showing that Hes1 protein expression inversely correlates with CDKN1C/P57 mRNA levels. In addition, reduced Hes1 protein expression is accompanied by a shorter time to recurrence after curative resection, suggesting that Hes1 may represent a biomarker for prediction of patients with poor prognosis.
Center for Applied Biomedical Research, S. Orsola-Malpighi University Hospital, Bologna, Italy. catia.giovannini4@unibo.it
Catia
C
Giovannini
Laura
L
Gramantieri
Manuela
M
Minguzzi
Francesca
F
Fornari
Pasquale
P
Chieco
Gian Luca
GL
Grazi
Luigi
L
Bolondi
D000368:Aged; D017209:Apoptosis / Q000235:genetics; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics*; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000473:pathology*; D002453:Cell Cycle / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D016922:Cellular Senescence / Q000235:genetics*; D047369:Chromatin Immunoprecipitation; D050761:Cyclin-Dependent Kinase Inhibitor p57 / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000473:pathology; D008297:Male; D008875:Middle Aged; D051881:Receptor, Notch1 / Q000378:metabolism*; D000071656:Receptor, Notch3; D051880:Receptors, Notch / Q000378:metabolism*; D012008:Recurrence; D015398:Signal Transduction; D013997:Time Factors; D000072056:Transcription Factor HES-1
D051792:Basic Helix-Loop-Helix Proteins; D050761:Cyclin-Dependent Kinase Inhibitor p57; D018398:Homeodomain Proteins; D051881:Receptor, Notch1; D000071656:Receptor, Notch3; D051880:Receptors, Notch; D000072056:Transcription Factor HES-1; C493964:CDKN1C protein, human; C497761:NOTCH1 protein, human; C499374:NOTCH3 protein, human; C078493:HES1 protein, human