Role of nutrients and TPL-2 protein kinase in cancer cells and their microenvironment – NuKiT

This projects combines transcriptomic analysis (microarray and qPCR) of MAPK mRNA expression in tumours with proteic analysis (western blot and IHC), proteomics and metabolomics. Moreover, new technologies such as Luminex will also be used to characterize up to 50 analytes constituting the tumour and its microenvironment. These data will be compared with tumours clinical properties. Finally, cell models (MAPK overexpression or transient/stable inactivation) and mice xenograft models will allow in vitro as well as in vivo analysis of MAPK function in tumour development. The molecular mechanisms of MAPK function will be decipher using classic biochemistry and molecular biology techniques. Mice xenograft models will also be useful to study MAPK effect on metastatic process and sensitivity to MAPK inhibitor treatments.

Our results clearly indicate MAPK controls epithelial cancer cell growth, by regulating cell cycle without affecting cell death. Within the tumour, MAPK is expressed not only in tumour cells but also in their microenvironment such as inflammatory cells and fibroblasts. We found tumours with high MAPK expression present an inflammatory signature. All these results confirm the importance of understanding MAPK double function in tumorigenesis: its autonomous function in cancer cells as well as its role in tumour microenvironment.
We also identified a potential mechanism regulating MAPK expression by miRNA. Indeed, our results show MAPK is a direct target of the miRNA. Morevover, miRNA expression in cancer cell lines inhibits endogenous MAPK expression. Finally, we also observed a differential regulation of MAPK expression by the miRNA depending on the culture medium used and we are trying to identify the component(s) involved.

This project’s originality is based upon 3 main characteristics: (i) it will be the first evidence of in vivo MAPK function in tumour development, metastasis, treatment sensitivity (ii) it will use cellular models and mice models (iii) it combines high throughput molecular techniques, cell biology and human tumour samples.
If MAPK pro-oncogenic function is proved and the mechanisms identified, we hope to develop a new therapy specifically targeting this protein kinase.

Neither publications nor patent have yet been submitted.

The serine threonine kinase TPL-2 (tumour progression locus 2) has been defined as an oncogene, in rodents, but the underlying mechanism remains unknown. Similarly, in humans, while somatic mutation of TPL2 seems to be quite rare in tumours, increased TPL-2 expression has been found in breast cancers, suggesting that TPL-2 might be involved in tumour development.
TPL-2 also named MAP3K8, activates MAPK and SAPK signalling pathways, both stimulating transduction pathways controlling cell growth, proliferation or survival. TPL-2 is also crucial for production of the pro-inflammatory cytokine TNFa, during inflammatory responses. TPL-2 might have a dual function in tumour development: 1) activation of signalling pathways promoting cell growth and survival; 2) enhancement of immune response. Both functions affecting either cancer cells or their microenvironment, once altered, might promote tumour development. Thereby, the basic research program we are willing to perform is aiming to determine the role of TPL-2 in tumour development by investigating TPL-2 function(s) in cancer cells and their microenvironment.
Interestingly, our data in a cohort of patients with various subtypes of breast cancer, indicates a significant increased in TPL-2 mRNA expression in the most aggressive subtype. This was confirmed in cancer cell lines. Similarly, high-grade serous ovarian tumours displaying high TPL-2 mRNA expression level were of poor prognosis. Thus, we have some strong evidences showing that TPL-2 might be involved in tumour development in humans. Using in vitro and in vivo models, we plan to decipher the molecular mechanism(s) involved in this process. We will focus on studying the signalling pathways as well as the influence of nutrients and oxidative stress that could also be involved in this process. Indeed, I have previously demonstrated that arginine, a nitric oxide precursor, is crucial for TPL-2 kinase activity.
The “Stress and Cancer” laboratory headed by Dr. Mechta-Grigoriou has expertise in oxidative stress regulation, metabolism and tumour development. Developing my project in this laboratory at the Institut Curie is giving me the best chance to obtain relevant strong data aiming to increase the basic research knowledge in the field of tumour growth.