Unfolding RFX1 Mediated Regulation of Cancer Stem Cells

Abstract

Regulatory factor X1(RFX1) is a unique transcription factor that can act both as an activator and repressor in a context‐dependent manner. In most of the cases, it has been shown to exert an inhibitory action on its targets. It belongs to the evolutionarily conserved RFX (Regulatory Factor binding to the X‐box) family of transcription factors consisting of eight homologs (RFX1‐8) in humans. RFX1 is seen down‐regulated in many cancers and is speculated to have a critical role in regulating stem cell properties. Cancer stem cells are major hurdles in cancer therapy as they are capable of repopulating a tumor after treatment. We aim to understand the regulation of cancer stemness by RFX1 in human teratocarcinomal (NTERA‐2) cancer stem like cells. We have chosen NTERA2 cl.D1 (NT2) embryonic carcinoma cells since they are the malignant counterparts of embryonic stem cells and are pluripotent in nature, making them an ideal candidate to be used as a cancer stem cell model. The cells were differentiated using DISC (Days in suspension culture) method to obtain differentiated populations (NT2D). Using real time analysis, the expression of RFX1 was evaluated in proliferating (NT2P) and differentiating (NT2D) cell populations. A significant increase in RFX1 expression was observed in NT2D cells compared to NT2P cells. For further validation, the same was done in stem cell population enriched using Abcg2 promoter where the stem (GFP+ve) and non‐stem (GFP‐ve) cell populations were sorted out by FACS. Further RFX1 expression was perturbed in NTERA cells, and the assessment of cardinal properties of CSCs, such as clonogenicity/self‐renewal properties, proliferation potential, and migration/invasive properties in vitro,revealed that RFX1 plays a significant role in cancer stemness. Therefore, understanding the regulation of cancer stemness by RFX1 will allow us to formulate better diagnostic and therapeutic approaches to address chemoresistant cancers.