Cytotoxic activity of NK cell-derived extracellular vesicles against cancer cells.

Our immune defence provides us a natural defence against cancer. Natural Killer (NK) cells is part of our immune system, and are specialized on seeking out and killing cancer cells. Cancer cells can avoid detection by the immune defence, and when this happenes the cancer cells can form a lump (tumor). NK cells are not good at gaining access to the tumor, and are often found powerless outside the tumor environment. NK cells uses toxic substances as their weapon. They inject the toxic components directly into the cancer cell. In addition, the NK cells releases nano-sized missiles containing the same toxic somponents. The missiles can seek out and kill cancer cells. In the laboratory we can culture NK cells, and make them produce the missiles. We can harvest the missiles, and use them to directly kill the cancer. With this project we will gain a better understanding of how the missiles are produced in NK cells, and how they seek out and destroy cancer cells. We hope that in the future, it will be possible to use this knowledge to design a cancer therapy.

With this project, we will build the basis for developing NK-cell derived extracellular vesicles (NK-EVs) as a new cancer therapeutics. NK cells and CAR-NK cells are already being exploited in therapies against hematological malignancies and solid tumors. With NK-EVs we will leverage on the combined power of the killing capacity of NK cells with that of the advantageous aspects of EVs as natural carriers of biomolecules and tissue penetration. We and others have demonstrated that NK-EVs induce apoptosis of a wide range of cancer cells in vitro, and a few studies have also shown efficacy in vivo. EVs are emerging as a new therapeutic avenue in several disease contexts, but the field needs to address and solve critical bottlenecks to allow their exploitation. This proposal will address two major knowledge needs, which is 1) to determine the mechanism of action of NK-EVs, and 2) to understand the heterogeneity of the NK-EV secretome to define the EV subset inducing cytotoxicity. To address these needs, we will perform CRISPR screens in two cancer cell lines to discover proteins that are necessary for mediating the effects of NK-EVs, further we will define the precise mechanism of action of how NK-EVs deliver their cytolytic cargo, and finally utilize single-EV technologies to dissect the EV secretome form NK cells released under different stimulatory conditions. Results from this study will be used to design production protocols and relevant potency assays which is a prerequisite for developing NK-EVs into a therapeutic product.