Team:UPF CRG Barcelona/Background
BACKGROUND AND DESIGN
Background
Control of metastasis remains a challenge to modern medicine. In fact, metastasis is responsible for 90% of tumor related deaths [1].
Lifestyle factors, such as diet, have been recently proved to have an strong influence on cancer development. The contribution of lipid metabolism in cancer progression has been long known; however, recent evidences suggest that diet-derived lipids can also contribute to the global lipid composition of cancer cells and thus to its development [2]. In fact, novel findings suggest that the acquisition of metastatic potential can rely on dietary long chain fatty acids (LCFA) intake, such as palmitic acid (PA) [3].
The exact role of this fatty acids (FAs) in cancer development is not fully understood; however, it has been hypothesized that this aberrant increase of FAs might provide cancer cells with structural substrates for new membranes, signalling metabolites and substrates for FA oxidation in order to fulfill the increased energy demand [4].
LCFA are one of the main components of our food intake. It has been reported that in Western diet, dietary lipids account for 42% of total ingested calories, 95% of which are triacylglycerols, mainly composed of long-chain fatty acids [5]. Considering these evidences and the infeasibility of FAs avoidance by dietary restriction, we hypothesized that targeting FAs availability in the intestine would stop cancer cells from spreading.
What is GARGANTUA?
In an attempt to propose a safe, effective and affordable solution to metastasis prevention we had the following idea:
What if we could develop a system capable of uptaking PA, acting as a fatty acid sponge? What if we could engineer commensal bacteria that already live in our gut flora to integrate this system in our body?
In this project we aim to design a probiotic with an enhanced metabolism able to increase its LCFA uptake and therefore reducing PA availability in the gut and the bloodstream. By doing so, we could halt tumor cells from becoming metastatic.
Thus, in the course of the project, we have focused on enhancing fatty acid intake, sensing fatty acids intracellularly and integrating this in to a bacteria such that it can be used as a live biotherapeutic.
Design
Enhancing E. Coli beta oxidation
In order to enhance E. coli’s own FA degradation machinery we have modulated the expression of the genes implicated in this metabolic process coupling them with an inducible promoter. This way, we have designed a plasmid compatible system containing all the beta-oxidation LCFA family genes.
Long Chain Fatty Acid Intracellular Biosensor
Our team has developed the first LCFA biosensor that does not interfere with its metabolism. Therefore, we have created the first genetic tool able to analyze LCFA degradation. This represents a powerful and robust system for quantifying FAs, which can be used for high throughput screening of organisms with an increased absorption of LCFA.
A live biotherapeutic
We asked ourselves what would be the best way to integrate our uptake system into a probiotic strain, addressing challenges that may arise when implementing Gargantua in a therapeutic context. We considered the genomic integration of our design, in order to achieve stable and robust expression and reducing biosafety concerns that can result from plasmid exchange. Thus, complying with current terapeutic standards for probiotic strain characteristics.
References
[1] Chaffer CL, Weinberg RA. A perspective on cancer cell metastasis. Science. 2011;331(6024):1,559–64.
[2] Baenke F, Peck B, Miess H, Schulze A. Hooked on fat: the role of lipid synthesis in cancer metabolism and tumour development. Disease models & mechanisms. 2013 6(6), 1353-1363.
[3] Pascual G, et al. Targeting metastasis-initiating cells through the fatty acid receptor CD36. Nature(2017): 41.
[4] Aranceta J, Pérez-Rodrigo C. Recommended dietary reference intakes, nutritional goals and dietary guidelines for fat and fatty acids: a systematic review. British Journal of Nutrition. 2012; 107(S2), S8-S22