High-throughput cell death assays

High-throughput screening identified mitoxantrone to induce death of hepatocellular carcinoma cells with autophagy involvement

The use of highly efficient high-throughput screening (HTS) platform has recently gained more attention as a plausible approach to identify de novo therapeutic application potential of conventional anti-tumor drugs for cancer treatments. In this study, we used hepatocellular carcinoma (HCC) cells as models to identify cytotoxic compounds by HTS. To identify cytotoxic compounds for potential HCC treatments, 3271 compounds from three well established small molecule libraries were screened against HCC cell lines. Thirty-two small molecules were identified from the primary screen to induce cell death. Particularly, mitoxantrone (MTX), which is an established antineoplastic drug, significantly and specifically inhibited the growth and proliferation of HCC cells in vitro. Mechanistic studies of LC3-II, p62 and phosphorylation of p70S6K in HepG2 cells revealed that MTX treatment induced mTOR-dependent autophagy activation, which was further confirmed by the autophagic flux assay using lysosomal inhibitor chloroquine (CQ). In the combined treatment of MTX and CQ, where autophagy was inhibited by CQ, the elevations of cleaved Caspase-3 and PARP were observed, indicating the enhanced apoptosis in HepG2 cells. Taken together, we hypothesize that MTX-induced autophagy plays an pro-survival role in HCC treatment. Combined treatment with autophagy inhibitor may combat the chemo-resistance of HCC to MTX treatment and therefore deserves future clinical investment.

High-Resolution Adhesion Kinetics of EGCG-Exposed Tumor Cells on Biomimetic Interfaces: Comparative Monitoring of Cell Viability Using Label-Free Biosensor and Classic End-Point Assays

A high-throughput label-free resonant waveguide grating biosensor, the Epic BenchTop, was utilized to in situ monitor the adhesion process of cancer cells on Arg-Gly-Asp tripeptide displaying biomimetic polymer surfaces. Using highly adherent human cervical adenocarcinoma (HeLa) cells as a model system, cell adhesion kinetic data with outstanding temporal resolution were obtained. We found that pre-exposing the cells to various concentrations of the main extract of green tea, the (-)-epigallocatechin gallate (EGCG), largely affected the temporal evolution of the adhesion process. For unexposed and low dosed cells, sigmoid shaped spreading kinetics was recorded. Higher dose of EGCG resulted in a complete absence of the sigmoidal character, and displayed adsorption-like kinetics. By using the first derivatives of the kinetic curves, a simple model was developed to quantify the sigmoidal character and the transition from sigmoidal to adsorption-like kinetics. The calculations showed that the transition happened at EGCG concentration of around 60 μg/mL. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide end-point assay, we concluded that EGCG is cytostatic but not cytotoxic. The effect of EGCG was also characterized by flow cytometry. We concluded that, using the introduced label-free methodology, the shape of the cell adhesion kinetic curves can be used to quantify in vitro cell viability in a fast, cost-effective, and highly sensitive manner.