Details

Autor(en) / Beteiligte

• Hao, Hongying
• Chen, Canming
• Rao, Xiao‐Mei
• Gomez‐Gutierrez, Jorge G.
• Zhou, H. Sam
• McMasters, Kelly M.

Titel

E2F‐1‐ and E2Ftr‐mediated apoptosis: the role of DREAM and HRK

Ist Teil von

• Journal of cellular and molecular medicine, 2012-03, Vol.16 (3), p.604-614

Ort / Verlag

Oxford, UK: Blackwell Publishing Ltd

Erscheinungsjahr

2012

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• E2F‐1‐deleted mutant, ‘truncated E2F’ (E2Ftr, E2F‐1[1–375]), lacking the carboxy‐terminal transactivation domain, was shown to be more potent at inducing cancer cell apoptosis than wild‐type E2F‐1 (wtE2F‐1; full‐length E2F‐1). Mechanisms by which wtE2F‐1 and E2Ftr induce apoptosis, however, are not fully elucidated. Our study demonstrates molecular effects of pro‐apoptotic BH3‐only Bcl‐2 family member Harakiri (Hrk) in wtE2F‐1‐ and E2Ftr‐induced melanoma cell apoptosis. We found that Hrk mRNA and Harakiri (HRK) protein expression was highly up‐regulated in melanoma cells in response to wtE2F‐1 and E2Ftr overexpression. HRK up‐regulation did not require the E2F‐1 transactivation domain. In addition, Hrk gene up‐regulation and HRK protein expression did not require p53 in cancer cells. Hrk knockdown by Hrk siRNA was associated with significantly reduced wtE2F‐1‐ and E2Ftr‐induced apoptosis. We also found that an upstream factor, ‘downstream regulatory element antagonist modulator’ (DREAM), may be involved in HRK‐mediated apoptosis in response to wtE2F‐1 and E2Ftr overexpression. DREAM expression levels increased following wtE2F‐1 and E2Ftr overexpression. Western blotting detected increased DREAM primarily in dimeric form. The homodimerization of DREAM resulting from wtE2F‐1 and E2Ftr overexpression may contribute to the decreased binding activity of DREAM to the 3′‐untranslated region of the Hrk gene as shown by electromobility shift assay. Results showed wtE2F‐1‐ and E2Ftr‐induced apoptosis is partially mediated by HRK. HRK function is regulated in response to DREAM. Our findings contribute to understanding the mechanisms that regulate wtE2F‐1‐ and E2Ftr‐induced apoptosis and provide insights into the further evaluation of how E2Ftr‐induced apoptosis may be used for therapeutic gain.