Cancer, Development and Adult Tissue Maintenance

 

Summary

Studying the link between normal development and disease, especially cancer. The Wt1 tumor suppressor gene and its role in kidney development has been the starting point for this, and we are studying both molecular and biological roles of the gene. Our work is now being extended to downstream genes, pathways and processes in different developing organs, including kidney, heart and neurons, as well as its potential role as an oncogene in adult cancer. Our current models suggest that whereas in the kidney the role of WT1 appears to be in stimulating cells to differentiate and exist the cell cycle, elsewhere in the developing embryo it could be doing the opposite by stimulating cell proliferation and keeping them in a mofre undifferentiated state.

 

Wt1 in Cancer

The development of a mouse model for Wilms’ tumors has been a long-standing goal of our lab. We are currently trying to use our conditional Wt1 knockout model to achieve this using different Cre lines. As WT1-mutant Wilms’ tumors almost invariably select for oncogenic mutations in ß-catenin, we have developed new ES and mouse models for different mutant forms of this gene. We are using these to study in more detail potential differences between different ß-catenin mutants, and analyse them in vivo in combination with the conditional Wt1 knockout.

 

In contrast to its role as tumor suppressor gene in Wilms’ tumors, there is an increasing body of evidence on different types of adult cancer where WT1 gets activated in tumors originating in tissues that normally don’t express the gene. Based on this it has been suggested WT1 could function as in oncogene in these cases. Though unexpected, there is data in the literature that would fit with this. For instance, in Wt1-deficient embryos several tissues outside the kidney have been found to have a decrease in cell proliferation rather than the expected increase, and also the proposed opposite roles in MET in the developing kidneys but EMT elsewhere would support an advantageous effect of activating WT1 for a developing epithelial cancer. O test this we have recently started a new project looking at a potential oncogenic role for WT1 in breast cancer, both in vitro and in vivo using our existing mouse models.

ES Technology

To facilitate the generation of new mouse models, we have further optimized the cloning procedure to generate Rosa26 knock-in construct, both for overexpression as well as knock-down experiments.

 

Collaborations

• European Union FP6 consortium EuReGene
• Professor Jamie Davies – University of Edinburgh
• Professor Ramon Muñoz Chapuli – University of Malaga
• Professor Haruo Sugiyama – University of Osaka
  

 

Lab Members

Current lab members involved in this work are:

• Professor Nick Hastie
• Dr Peter Hohenstein
• Abdelkader Essafi
• You-Ying Chau
• Joan Slight
• Rachel Berry
• Paul Devenney
• Anna Thornburn
• Victor Velecela
• Mara Artibani
• Asier Unciti-Broceta
• Eve Victoria Miller-Hodges

 

1. Molecular functions of WT1
2. WT1 in kidney development
3. Wt1 and Wnt4 (this page)
4. Wt1 outside the Kidney (this page)
5. WT1 in MET and EMT (this page)
6. Wt1 in Cancer (this page)
7. ES Technology (this page)
8. Publications

 

Wt1 and Wnt4

We have shown that the Wt1 knockdown phenotype in organ culture is identical to the Wnt4 knockdown and knockout phenotypes, and we have now data to show that Wnt4 is functionally downstream of Wt1 in the induction of nephron formation. Wnt4 has already been suggested to be a transcriptional downstream target for Wt1 in vitro, but so far it hasn’t been clear if it is a direct or an indirect target. We are currently analysing some candidate regions in the Wnt4 upstream region for regulation by Wt1. To understand the downstream effects of Wt1 and Wnt4 in the developing kidney we have begun to analyse the downstream pathways activated by Wnt4 in the condensing mesenchyme. According to our data the canonical pathway mediated by ß-catenin can not be directly downstream of Wnt4 in the kidney. Instead, we have begun analysing the non-canonical pathways. We are doing this with a combination of kidney organ culture and new mouse models.

 

Wt1 Outside the Kidney

Besides the kidney we have also begun to analyse the role of Wt1 in heart and neuronal development using the appropriate Cre expressing lines. In collaboration with Prof Muñoz Chapuli we have identified the retinoic acid synthesis pathway as an important downstream target of Wt1 in the developing heart, as well as a role for Wt1 in normal development of the liver.

 

Figure 3: Model for the tole of Wt1 and RA metabolism in hepatic development. Adapted from IJpenberg et al (2007).

WT1 in MET and EMT

Many lines of evidence suggest a role for Wt1 in regulating EMT and MET processes. This has been supported by the analysis of Wt1-/-and Wt1-GFP ES cells. In line with this we have now identified a major regulator of EMT as a direct transcriptional target of Wt1. In the near future we will be analysing the role of this gene and the EMT and MET processes in the different phenotypes found in Wt1-mutant mice. It is possible that the opposite functions of WT1 in MET and EMT are an important aspect of the opposite functions in different tissues.