Fanconi anemia proteins counteract the implementation of the oncogene-induced senescence program

Anne Helbling-Leclerc,Filippo Rosselli,Françoise Dessarps-Freichey,Caroline Evrard

doi:10.1038/s41598-019-53502-w

Abstract

Fanconi Anemia (FA), due to the loss-of-function of the proteins that constitute the FANC pathway involved in DNA replication and genetic stability maintainance, is a rare genetic disease featuring bone marrow failure, developmental abnormalities and cancer predisposition. Similar clinical stigmas have also been associated with alterations in the senescence program, which is activated in physiological or stress situations, including the unscheduled, chronic, activation of an oncogene (oncogene induced senescence, OIS). Here, we wanted to determine the crosstalk, if any, between the FANC pathway and the OIS process. OIS was analyzed in two known cellular models, IMR90-hTERT/ER:RASG12V and WI38-hTERT/ER:GFP:RAF1, harboring 4-hydroxytamoxifen-inducible oncogenes. We observed that oncogene activation induces a transitory increase of both FANCA and FANCD2 as well as FANCD2 monoubiquitination, readout of FANC pathway activation, followed by their degradation. FANCD2 depletion, which leads to a pre-senescent phenotype, anticipates OIS progression. Coherently, FANCD2 overexpression or inhibition of its proteosomal-dependent degradation slightly delays OIS progression. The pro-senescence protease cathepsin L, which activation is anticipated during OIS in FANCD2-depleted cells, also participates to FANCD2 degradation. Our results demonstrate that oncogene activation is first associated with FANCD2 induction and activation, which may support initial cell proliferation, followed by its degradation/downregulation when OIS proceeds.

Highlights

Fanconi Anemia (FA), due to the loss-of-function of the proteins that constitute the FANC pathway involved in DNA replication and genetic stability maintainance, is a rare genetic disease featuring bone marrow failure, developmental abnormalities and cancer predisposition
RAS expression in IMR90* cells led to approximately 40% of cells presenting nuclear senescence associated heterochromatin foci (SAHF) one week after 4HT exposure, whereas a WI38* cell population expressing RAF1 reached a similar level of senescent cells in around 72 h
Oncogene activation is followed by a wave of replication within 24 h before undergoing growth arrest in both G1 and G2 (Fig. 1C,D and Supplemental Fig. S1A,B), suggesting that oncogene activation leads to a “go” signal, which pushes G1-licensed cells to a rapid entry in replication followed by a “stop” signal that “freezes” the cells in G1 and G2, impeding proliferation

Summary

Introduction

Fanconi Anemia (FA), due to the loss-of-function of the proteins that constitute the FANC pathway involved in DNA replication and genetic stability maintainance, is a rare genetic disease featuring bone marrow failure, developmental abnormalities and cancer predisposition. A situation exemplified by the human nevi containing melanocytes that, despite the presence in their genome of oncogene activating mutations, may remain for decades in a non-proliferating status before their eventual awakening and progression to melanoma[15] It is not clear how an oncogene-induced senescent cell may by-pass the established senescent program and re-enter in proliferation, proteins involved in DNA damage response (DDR) appear to have a role in both senescent establishment and escaping[16,17,18,19]. FANC pathway loss-of-function was associated with the induction of several genes/ proteins that negatively control cell cycle progression, including p53, p21 and p16, with the cellular accumulation of reactive oxygen species (ROS) and with alterations in both TGFβ-SMAD and PI3K-FOXO pathways[22,26,27,28]. Little is known about how the FANC pathway regulates senescence

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Results

Conclusion