Repeated H2 O2 exposure drives cell cycle progression in an in vitro model of ulcerative colitis.
J Cell Mol Med
; 17(12): 1619-31, 2013 Dec.
Article
em En
| MEDLINE
| ID: mdl-24118792
ABSTRACT
The production of hydrogen peroxide (H2 O2 ) drives tumourigenesis in ulcerative colitis (UC). Recently, we showed that H2 O2 activates DNA damage checkpoints in human colonic epithelial cells (HCEC) through c-Jun N-terminal Kinases (JNK) that induces p21(WAF1) . Moreover, caspases circumvented the G1/S and intra-S checkpoints, and cells accumulated in G2/M. The latter observation raised the question of whether repeated H2 O2 exposures alter JNK activation, thereby promoting a direct passage of cells from G2/M arrest to driven cell cycle progression. Here, we report that increased proliferation of repeatedly H2 O2 -exposed HCEC cells (C-cell cultures) was associated with (i) increased phospho-p46 JNK, (ii) decreased total JNK and phospho-p54 JNK and (iii) p21(WAF1) down-regulation. Altered JNK activation and p21(WAF1) down-regulation were accompanied by defects in maintaining G2/M and mitotic spindle checkpoints through adaptation, as well as by apoptosis resistance following H2 O2 exposure. This may cause increased proliferation of C-cell cultures, a defining initiating feature in the inflammation-carcinoma pathway in UC. We further suggest that dysregulated JNK activation is attributed to a non-apoptotic function of caspases, causing checkpoint adaptation in C-cell cultures. Additionally, loss of cell-contact inhibition and the overcoming of senescence, hallmarks of cancer, contributed to increased proliferation. Furthermore, there was evidence that p54 JNK inactivation is responsible for loss of cell-contact inhibition. We present a cellular model of UC and suggest a sinusoidal pattern of proliferation, which is triggered by H2 O2 -induced reactive oxygen species generation, involving an interplay between JNK activation/inactivation, p21(WAF1) , c-Fos, c-Jun/phospho-c-Jun, ATF2/phospho-ATF2, ß-catenin/TCF4-signalling, c-Myc, CDK6 and Cyclin D2, leading to driven cell cycle progression.
Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Colite Ulcerativa
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Ciclo Celular
/
Peróxido de Hidrogênio
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Modelos Biológicos
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article