Flow cytometric phenotyping of diverse human cancer cell lines for immunological biomarkers expression

The tumour microenvironment contains a variety of distinct factors that inhibit the immune system and can cause drug resistance. Some of these factors include the expression of cell surface markers which interact directly with immune cells. Cancer cells express programmed death ligand 1 (PD-L1) and reduce the expression of major-histocompatibility complex class I, death-receptors 4/5 and Fas, limiting immune-mediated cancer cell killing. Targeting these immune markers alone or in combination could potentially increase cancer cell death and improve drug efficacy. Utilising flow cytometric analysis on breast, prostate and colorectal cancer cell lines, we have found differential expression of these markers depending on the cancer type. These findings provide a platform for future work that will entail siRNA knockdown of PD-L1 to determine the tumour-intrinsic role of this ligand, in addition to combination therapies in 2D and 3D cell culture.