Mathematical modeling of synthetic-dosage gene interactions leading to EMT-like phenotype in colon

cancer mouse modelDavid PA Cohen1,2,3, Laurence Calzone1,2,3, I Kuperstein1,2,3, M Chanrion1,, C Barrière1, F El-Marjou1, D Vignjevic1, L Stimmer1, I Bieche1, S Dos Reis Tavares1, GF Boccia1, W Cacheux1,

D Meseure1, S Fré1, L Martignetti1,2,3, P Paul-Gilloteaux1, L Fetler1, E Barillot1,2,3, D Louvard1, A Zinovyev1,2,3 and S Robine1

(1) Institut Curie (2) INSERM U900 (3) Ecole des Mines ParisTech, Paris, France

Ex vivo analysis of tumour slices by 2-photon microscopy. A compound mouse harbouring an inducible NICD gain of function and p53 loss of function mutations has been developed. Ex vivo slices of the tumours that developed in these mice, were stained for GFP (epithelial cells) and collagen I (pink). Cancer cells invading stroma as clusters and strings parallel to the collagen fibers

Boolean modeling of an influence network showed that for the wild type cell three possible cell decission can be made (see table). In case of the NICD gain of function mutant, there are two possibilities: apoptosis or EMT. For the p53 loss of function mutation and for the NICD gain of function / p53 loss of function there is only one cell fate decission, apoptosis or EMT, respectively. When simulations are performed with initial conditions from the 3 possible cell decissions in the wild type and are perturbed for NICD mutation, stable state 5 is never reached but state 4, if then p53 is perturbed stable state 7 is reached. If first p53 mutation is performed, stable state 6 is reached followed by the second mutation, stable state 7.

Acknowledgements: This project is supported by ITMO Cancer 2012 INVADE project and Projet Incitatif Collaboratif “Computational Systems Biology Approach for Cancer” at Institut Curie. I.K., D.C., L.C., E.B. and A.Z. are members of the Computational Systems Biology of Cancer team, ” Equipe labellisée par la Ligue Nationale Contre le Cancer. 

M. Charion et al. Notch activation and p53 deletion induce EMT-like processes and metastasis in a novel mouse model of intestinal cancer. submitted

Panel A: a reaction network has been constructed manually by using literature and CellDesigner software. This network depicts mainly the interactions between several pathways and their target genes and phenotypes. The gene transcription profile of genes that are involved in EMT are indicated in the enlarged box. Network analysis has shown highly connected nodes (red boxes) on which reduced influence network is based (panel B and C).

Network construction

EMT model

Boolean model Mouse model

EMT is induced by five transcription factors (TF): Snail, Slug, Zeb1/2 and Twist. These TFs and proliferation are regulated positively by Notch pathway while apoptosis is inhibited. The p53 family regulate negatively EMT, proliferation and stimulating apoptosis, thereby inhibiting metastasis and progression of cancer. EMT induces proliferation and inhibits apoptosis thereby having a positive effect on metastasis.

In colon cancer, 25-35% of the patients will develop metastases during the disease. The aim of the study is to develop a mouse model that mimics the human disease including EMT and metastasis. Using a Systems Biology approach, a synergy between loss of p53 and activated Notch (NICD)

pathway was identified that would be responsible for EMT, while the Wnt pathway activation is a later event that sustains EMT

Panel A: a mechanistic model that can explain the effect of different mutations on the EMT-like phenotype. This model is based on the following assumptions: 1) Activated Notch pathway ‘depicted by NICD) and p53 family have opposing effects on EMT, proliferation and apoptosis. 2) NICD acts at transcriptional level while p53 acts, via miRNA, by suppressing translation of target mRNA. 3) NICD induce all five key EMT inducers, p53 inhibits these via miRNA. 5) EMT can only be activated when the 5 EMT-inducers are activated. 6) NICD activates EMT, EMT induces Wnt pathway by increasing beta-catenin. Panel B shows wild type (upper left), p53 loss of function (upper right), NICD gain of function (bottom left) and the NICD gain of function with p53 loss of function phenotypes and their effect on inducing EMT-like phenotype.

Mechanistic model

A

p53 is down

NICD is up

NICD

NICD is up and

NICD

p53 is down

B