Unravelling the anti-cancer mechanism of small molecule drugs that modulate novel target in the tumor microenvironment

Abstract

The tumor microenvironment (TME) is composed of intratumoral cell groups such as vascular cells, stromal cells or immune cells and even extracellular substrates or hypoxia. Of the many components that compose the TME, cancer-associated fibroblasts (CAF) and tumor-associated macrophage (TAM) are key components. CAF are activated compared to normal, tissue resident fibroblasts. CAF express marker genes and secrete specific cytokines at a greater rate than normal fibroblasts. Moreover, TAM show a phenotype that reflects their tumor origin and is distinct from normal macrophages or related-immune cells. There is an intercellular communication (termed crosstalk) between CAF and TAM than regulate tumor growth and metastasis. Previous research has shown that the cytokines IL-6 or GM-CSF are a key component of the crosstalk between CAF and TAM. In this thesis, FDA approved drugs were screened to select candidates that can target the IL-6 and downstream JAK/STAT signaling pathway in CAF. The MTT assay and ELISA were used to test CAF viability IL-6 cytokine expression, respectively. A hit drug, termed NDT-SOR, was selected as a best candidate. NDT-SOR downregulated IL-6 expression in human CAFs and immortalized hTERT fibroblasts stimulated by cancer cell YD-10B conditioned media (CM). Using western blotting, it was shown that NDT-SOR downregulates the expression of some members of the JAK/STAT pathway. Using co-culture assays with CAF, NDT-SOR was found to restrict monocyte differentiation and polarization into macrophages. Furthermore, these NDT-SOR treated monocytes showed reduced expression of TAM-specific genes, such as IL-10 or CD-206, compared to normal monocytes after co-culture. Additionally, invasion assay analyses show that NDT-SOR treatment reduced the ability of TAM to induce cancer cell migration. These results indicate that there are some crosstalk between CAF, TAM and cancer cells, and also NDT-SOR was newly discovered to be a drug that could inhibit the crosstalk, confirming the possibility of being a potential drug.