Inhibition of Mitochondrial Dynamics by Mitochondrial Division Inhibitor-1 Suppresses Cell Migration and Metastatic Markers in Colorectal Cancer HCT116 Cells.

Abstract

Introduction: The mitochondria are highly dynamic organelles. The mitochondrial morphology and spatial distribution within the cell is determined by fusion and fission processes of mitochondria. Several studies have used mitochondrial division inhibitor-1 (Mdivi.1) to explore the roles of mitochondrial dynamics in various pathological conditions, including diabetic cardiomyopathy, myocardial infarction, cardiac hypertrophy, Alzheimer's disease, Huntington's disease and cancers.

Purpose: The objective of the study was to investigate the role of mitochondrial dynamics in the invasiveness of HCT116 colorectal cancer cells.

Material and methods: MTT assay was used to determine the Mdivi.1-induced toxicity in HCT116 cells. Wound healing, cell migration and colony forming assays were adopted to measure the migration and invasion activity of HCT116 cells. Furthermore, flow cytometry was used to determine the Mdivi.1-induced mitochondrial mass quantification, mitochondrial membrane potential and reactive oxygen species generation in HCT116 cells. Additionally, Western Blot analysis was used to determine the expression level of Drp1, p-Drp1, Mnf2, AMPK-α, p-AMPK-α, Cox-2, iNos and MMP9 in HCT116 cells.

Results: We found that Mdivi.1 induced toxicity and altered the morphology of HCT116 cells in concentration- and time-dependent manners. Mdivi.1 significantly increased mitochondrial mass and dissipated the mitochondrial membrane potential. Furthermore, Mdivi.1 induced reactive oxygen species (ROS) generation and mitochondrial superoxide production, leading to AMPK activation. Moreover, Mdivi.1 decreased dynamin-related protein-1 (Drp1) and phosphorylated-Drp1 expression and increased mitofusin-2 (Mfn2) expression in a concentration-dependent manner at 48 and 72 h post-treatment. Notably, Mdivi.1 induced inhibition of translocation of Drp1 from the cytosol to the outer mitochondrial membrane. Mdivi.1 significantly suppressed the invasion and migration of HCT116 cells and inhibited the formation of HCT116 cell colonies. In addition, Mdivi.1 significantly decreased the expression of metastatic markers including Cox-2, iNos, and MMP-9 in HCT116 cells.

Conclusion: Collectively, this study revealed that Mdivi.1 downregulates Drp1, upregulates Mfn2, and increases mitochondrial mass with attenuated oxidative metabolism, leading to the inhibition of cell invasion and metastasis in colorectal cancer HCT116 cells. Mitochondrial dynamics are regarded as possible drug targets for interrupting colorectal cancer cell migration and metastasis.