MiR 378a/FSCN1 regulatory axis inhibits tumor stemness and increases the cytotoxicity of chemotherapeutic drugs in colorectal cancer cells

Abstract

Purpose: To evaluate the effect of miR-378a/FSCN1 axis on tumor stemness and aerobic glycolysis in colorectal cancer cells (CRC).
 Methods: Abnormal expressions of miR-378a and FSCN1 in CRC tissues were analyzed through TCGA database. Cell viability and apoptosis were determined using 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di- phenytetrazoliumromide (MTT) assay and flow cytometry, respectively, while expression of miR-378a was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). Furthermore, Western blotting assay was used to assess protein expressions. The miR-378a target was evaluated using ENCORI and confirmed by luciferase assay. Aerobic glycolysis was evaluated by determining glucose uptake, lactate production and lactate dehydrogenase (LDH) activity.
 Results: Downregulation of miR-378a and upregulation of FSCN1 were observed in both CRC tissues and cell lines (p < 0.05). Overexpression of miR-378a and repression of FSCN1 reduced cell viability and tumor sphere formation, and induced cell apoptosis. Protein expression of SOX2, KLF4, Bmi1 and Oct-4 were downregulated by either the overexpression of miR-378a or repression of FSCN1 (p < 0.01). Glucose uptake, lactate production and LDH activity were inhibited by either overexpression of miR-378a or repression of FSCN1, while cytotoxicity of Dox and 5-Fu was increased by upregulation of miR-378a or downregulation of FSCN1 (p < 0.05). The predictive results of ENCORI demonstrated that FSCN1 was the direct target of miR-378a, and this was confirmed by luciferase assay results (p < 0.005). All the effects of miR-378a in CRC were reversed by overexpression of FSCN1 (p < 0.05).
 Conclusion: This study has shown that miR-378a suppresses tumor stemness and increases the cytotoxicity of chemotherapeutic drugs by directly targeting FSCN1, resulting in the prevention of CRC tumorigenesis. Thus, these findings suggest a new approach to the chemotherapeutic management of CRC.