Thymoquinone challenges UHRF1 to commit auto-ubiquitination: a key event for apoptosis induction in cancer cells.

Fiche publication

Date publication

juin 2018

Journal

Oncotarget

Auteurs

Membres identifiés du Cancéropôle Est :
Dr BRONNER Christian , Dr HAMICHE Ali , Pr MELY Yves , Dr MOUSLI Marc

Tous les auteurs :
Ibrahim A, Alhosin M, Papin C, Ouararhni K, Omran Z, Zamzami MA, Al-Malki AL, Choudhry H, Mély Y, Hamiche A, Mousli M, Bronner C

Lien Pubmed

https://www.ncbi.nlm.nih.gov/pubmed/29983883

Résumé

Down-regulation of UHRF1 (Ubiquitin-like containing PHD and Ring Finger 1) in Jurkat cells, induced by natural anticancer compounds such as thymoquinone, allows re-expression of tumor suppressor genes such as and . In order to decipher the mechanisms of UHRF1 down-regulation, we investigated the kinetic of expression of HAUSP (herpes virus-associated ubiquitin-specific protease), UHRF1, cleaved caspase-3 and p73 in Jurkat cells treated with thymoquinone. We found that thymoquinone induced degradation of UHRF1, correlated with a sharp decrease in HAUSP and an increase in cleaved caspase-3 and p73. UHRF1 concomitantly underwent a rapid ubiquitination in response to thymoquinone and this effect was not observed in the cells expressing mutant UHRF1 RING domain, suggesting that UHRF1 commits an auto-ubiquitination through its RING domain in response to thymoquinone treatment. Exposure of cells to Z-DEVD, an inhibitor of caspase-3 markedly reduced the thymoquinone-induced down-regulation of UHRF1, while proteosomal inhibitor MG132 had no such effect. The present findings indicate that thymoquinone induces in cancer cells a fast UHRF1 auto-ubiquitination through its RING domain associated with HAUSP down-regulation. They further suggest that thymoquinone-induced UHRF1 auto-ubiquitination followed by its degradation is a key event in inducing apoptosis through a proteasome-independent mechanism.