Biology session

The most common cancer of the pancreas is pancreatic ductal adenocarcinoma (PDAC) and it is one of the deadliest cancer types on the whole world. Tumorigenesis of PDAC is generally determined by mutations of the KRAS oncogene and the TP53 tumor suppressor gene; in addition simultaneous pancreas inflammation contributes to poor prognosis. Interactions between tumor stroma and tumor cells in PDAC in paracrine manner, transmitted by cytokines and growth factors influence the aggressive feature of this cancer. The most notable cells of the stroma are fibroblasts which are constituted by different populations: they show myofibroblastic (αSMA expression) or inflammatory fibroblastic (cytokine secretion) phenotypes. One specific mode of communication in the tumor microenvironmet is the release and uptake of extracellular vesicles (EV). EVs carry biologically active molecules surrounded by lipid bilayers in a protected way.

My aim was 1.) to characterise the PDAC-derived organoids and stromal cells with appropriate markers, 2.) to measure the expression of cytokines/growth factors and their receptors in PDAC-derived organoids and stromal cells 3.) to measure their EV release, further 4.) to describe the activation of stromal cell cultures, and finally 5.) to identify the KRAS and TP53 hotspot mutations of organoids and stromal cells.

In my work I characterised the PDAC-derived organoids and stromal cells with markers described in the literature. Furthermore RT-qPCR measurements showed different expressions of cytokines/growth factors and their receptors between stromal cells and organoids. I show that PDAC-derived cultures release CD63 (exosome marker) positive EVs, surprisingly stromal cells release more EVs than organoids. In addition, I observed that the expression of activated fibroblast-markers and the releasing of EVs by stromal cell cultures change upon long-time cultivation.

These data prove that PDAC-derived organoids and PDAC-derived stromal cell cultures release EVs which can be detected easily from cell culture media with special beads and flow cytometry. Furthermore, my data demonstrate the importance of crosstalk between tumor cells and stomal cells in the PDAC microenvironment and support the relevance of EVs in this crosstalk.

Kutatási támogatások: OTKA-NN-118018, NVKP-16-0007, ICGEB-CRP, Felsőoktatási Intézményi Kiválósági Program