Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - Secret Surface (The cell surface tetraspanin web drives tumour development and alters metabolic signalling)

Teaser

Cancer development is characterized by uncontrolled proliferation, cell survival and metabolic reprogramming. Tumour cells are surrounded by a fluid-mosaic membrane that contains tetraspanins (Tspans) which are evolutionary conserved proteins important in the formation of...

Summary

Cancer development is characterized by uncontrolled proliferation, cell survival and metabolic reprogramming. Tumour cells are surrounded by a fluid-mosaic membrane that contains tetraspanins (Tspans) which are evolutionary conserved proteins important in the formation of multiprotein complexes at the cell surface (‘tetraspanin web’). Increasing evidence indicates that Tspans are involved in cancer, still the architecture of the Tspan web in native tumour membranes and its (patho)physiological functions have not been resolved.
Based on my preliminary data, I hypothesize that tumour cells contain a disrupted Tspan web in which Tspan interactions are modified leading to aberrant metabolic signalling and tumour development. This is supported by my discovery that loss of Tspan CD37 leads to spontaneous lymphomagenesis due to activation of the Akt survival pathway. The overall aim of Secret Surface is to unravel the composition, physiological functions and molecular mechanisms of the Tspan web on tumour development and clinical outcome. To achieve this, I will focus on studying lymphomas using a multidisciplinary approach: I. Detailed analyses of Tspan web composition in lymphoma to select clinically relevant Tspans (high-throughput tissue microarray technology, multispectral imaging). II. Resolve the endogenous Tspan web on lymphoma cells (super-resolution microscopy), and generation and analysis of lymphoma cells that have a complete deficiency of multiple Tspans (CRISPR/Cas9 technology). III. Decipher molecular mechanisms underlying Tspan web function in lymphoma cells (membrane organization, membrane-proximal signalling, metabolic reprogramming). With my unique toolbox of Tspan knock-outs coupled to advanced microscopy and metabolic studies, I expect that Secret Surface will lead to a new concept in cellular physiology in which cell surface organization by the Tspan web drives tumour development, which may open new horizons for the generation of new cancer therapies.

Work performed

The overall aim of Secret Surface is to unravel the composition, physiological functions and underlying molecular mechanisms of the cell surface tetraspanin web on tumour behaviour and clinical outcome in cancer patients.
Aim I. Tetraspanin web on lymphoma. We investigated tetraspanin expression at the protein level in a discovery cohort of diffuse large B cell lymphoma tissues using tissue microarray technology. CD151 was differentially expressed in lymphoma tissues and we are currently analysing the relation to the clinical outcome (survival data) and underlying molecular mechanisms.
Aim II. Resolving the endogenous Tspan web on healthy and lymphoma B cells. As proof-of-principle we set-up dSTORM super-resolution microscopy of tetraspanin CD9 in B cell lines and collected the first images. The challenge is the accurate analysis of the large data sets in terms of cluster size, diameter and number molecules/cluster.
Aim III. Deciphering molecular mechanisms underlying Tspan web function in lymphoma cells (membrane protein organisation, signalling pathways, metabolic reprogramming). Using an unbiased metabolomics approach, we discovered that lymphoma B-cells deficient in CD37 have altered metabolic pathways resulting in increased fatty acid oxidation and higher ATP production. We are currently validating these findings in primary lymphoma cells, and the next step is to identify the underlying molecular mechanisms.

Final results

The overall aim of Secret Surface is to unravel the composition, physiological functions and underlying molecular mechanisms of the cell surface tetraspanin web on tumour behaviour and clinical outcome in cancer patients. To achieve this challenge, I will focus on studying the Tspan web on haematological malignancies (lymphomas) using a multidisciplinary approach composed of 3 interrelated work packages:
WPI. Tspan web in lymphoma patients. Detailed analyses of Tspan web composition in lymphoma and clinical outcome in patients through high-throughput tissue microarray technology and multispectral imaging.
WPII. Modulation and characterisation of the Tspan web. A. Resolving the endogenous Tspan web on lymphoma B cells (super-resolution microscopy), and B. generation and functional characterization of lymphoma cells that have are completely deficient in relevant Tspans (CRISPR/Cas9 technology).
WPIII. Tspan-mediated signalling mechanisms. A. Deciphering molecular mechanisms underlying Tspan web function in lymphoma cells (membrane protein organisation, membrane-proximal signalling, metabolic reprogramming), and B. validation in selected preclinical mouse models.
With my unique toolbox of lymphoma tissue microarrays and Tspan knock-outs coupled to advanced microscopy and metabolic studies, I expect that Secret Surface will lead to a new concept in cellular physiology in which cell surface organisation by the Tspan web drives tumour development. Since tetraspanins are highly conserved in evolution and expressed at the cell surface of virtually all cells and tissue types, Secret Surface will open up new research horizons for the different fields of oncology, cell biology and physiology