NEW WORK ON FOXM1 IN ONCOGENE -OPEN ACCES

http://www.nature.com/onc/journal/vaop/ncurrent/full/onc2016262a.htmlOriginal Article

Oncogene advance online publication 25 July 2016; doi: 10.1038/onc.2016.262

FOXM1 allows human keratinocytes to bypass the oncogene-induced differentiation checkpoint in response to gain of MYC or loss of p53

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R Molinuevo¹, A Freije¹, I de Pedro¹, S W Stoll², J T Elder^2,3 and A Gandarillas^1,4

1. ¹Cell Cycle, Stem Cell Fate and Cancer Laboratory, Institute of Research Marqués de Valdecilla (IDIVAL), Santander, Spain
2. ²Department of Dermatology, University of Michigan, Ann Arbor, MI, USA
3. ³Department of Ann Arbor Veterans Affairs Health System, Ann Arbor, MI, USA
4. ⁴INSERM, Languedoc-Roussillon, Montpellier, France

Correspondence: Dr A Gandarillas, Cell Cycle, Stem Cell Fate and Cancer Laboratory, Institute of Research Marqués de Valdecilla (IDIVAL), Cardenal Herrera Oria s/n, Santander, Cantabria 39011, Spain. E-mail: agandarillas@idival.org

Received 28 October 2015; Revised 2 June 2016; Accepted 16 June 2016
Advance online publication 25 July 2016

Abstract

Tumour suppressor p53 or proto-oncogene MYC is frequently altered in squamous carcinomas, but this is insufficient to drive carcinogenesis. We have shown that overactivation of MYC or loss of p53 via DNA damage triggers an anti-oncogenic differentiation-mitosis checkpoint in human epidermal keratinocytes, resulting in impaired cell division and squamous differentiation. Forkhead box M1 (FOXM1) is a transcription factor recently proposed to govern the expression of a set of mitotic genes. Deregulation of FOXM1 occurs in a wide variety of epithelial malignancies. We have ectopically expressed FOXM1 in keratinocytes of the skin after overexpression of MYC or inactivation of endogenous p53. Ectopic FOXM1 rescues the proliferative capacity of MYC- or p53-mutant cells in spite of higher genetic damage and a larger cell size typical of differentiation. As a consequence, differentiation induced by loss of p53 or MYC is converted into increased proliferation and keratinocytes displaying genomic instability are maintained within the proliferative compartment. The results demonstrate that keratinocyte oncogene-induced differentiation is caused by mitosis control and provide new insight into the mechanisms driving malignant progression in squamous cancer.