Assessing the effect of cisplatin on mitochondria in monocytes and macrophages

Abstract

Cisplatin is a platinum based chemotherapeutic agent which is widely used to treat a variety of solid tumours. However, the use of cisplatin is limited because of its side effects such as nephrotoxicity, neurotoxicity, ototoxicity, and peripheral neuropathy. Clinically this has become more of a problem over the past 10 years as cancer survivorship has dramatically increased. The mechanism behind how cisplatin induces toxicity is still unclear. We aim to evaluate the effects of cisplatin on mitochondrial metabolism in monocytes and macrophages. THP-1 Blue, a human acute monocytic leukaemia cell line, was used in this study. THP- 1 Blue monocytes were differentiated into macrophages using 20 ng/ml PMA. Mitochondrial activity was determined by MTT assay, and cell viability was determined using Trypan blue assay. Mitochondrial function was assessed using Mito tracker red CMROS and nano live microscopy, and the change in mitochondrial respiration was assessed using the seahorse XF Cell Mito stress test kit. NF-KB activation was measured using Quanti-Blue assay, and IL-6 was measured using an ELISA. Cisplatin dose-dependently decreased mitochondrial activity in THP-1 Blue monocytes and macrophages. Cisplatin caused mitochondrial dysfunction and induced cell death in THP-1 Blue macrophages after exposure to high dose (30 μg/ml) and even at low dose (5 μg/ml) decreased mitochondrial respiration after 24 hours. However, cisplatin treatment did not significantly affect NF-KB signaling in monocytes or macrophages. Also, IL-6 levels were undetectable in THP-1 Blue macrophages after exposure to different concentrations of cisplatin. Therefore, there is a relationship between mitochondrial dysfunction and cisplatin induced toxicity in this cell line. However, further studies are needed to investigate more on macrophages to see if cisplatin triggers inflammation.