In Vitro Cell Toxicity and Intracellular Uptake of Doxorubicin Exposed as a Solution or Liposomes: Implications for Treatment of Hepatocellular Carcinoma

Abstract

Cytostatic effects of doxorubicin in clinically applied doses are often inadequate and limited by systemic toxicity. The main objective of this in vitro study was to determine the anti-tumoral effect (IC50) and intracellular accumulation of free and liposomal doxorubicin (DOX) in four human cancer cell lines (HepG2, Huh7, SNU449 and MCF7). The results of this study showed a correlation between longer DOX exposure time and lower IC50 values, which can be attributed to an increased cellular uptake and intracellular exposure of DOX, ultimately leading to cell death. We found that the total intracellular concentrations of DOX were a median value of 230 times higher than the exposure concentrations after exposure to free DOX. The intracellular uptake of DOX from solution was at least 10 times higher than from liposomal formulation. A physiologically based pharmacokinetic model was developed to translate these novel quantitative findings to a clinical context and to simulate clinically relevant drug concentration–time curves. This showed that a liver tumor resembling the liver cancer cell line SNU449, the most resistant cell line in this study, would not reach therapeutic exposure at a standard clinical parenteral dose of doxorubicin (50 mg/m2), which is serious limitation for this drug. This study emphasizes the importance of in-vitro to in-vivo translations in the assessment of clinical consequence of experimental findings.

Limitations and Possibilities of Transarterial Chemotherapeutic Treatment of Hepatocellular Carcinoma

“…Both cTACE and DEM-TACE are considered to produce a better anti-tumour response in tumours with a high degree of vascularity [ 64 ]. A correlation between a longer doxorubicin exposure time and lower cytostatic effect (IC50) has been established in four human cancer cell lines (HepG2, Huh7, SNU449 and MCF7) [ 65 ]. This can be explained by an increased cellular uptake and intracellular exposure of doxorubicin, which was observed to accumulate intracellularly where concentrations were 230 times higher than exposure concentrations [ 65 ].…”

“…A correlation between a longer doxorubicin exposure time and lower cytostatic effect (IC50) has been established in four human cancer cell lines (HepG2, Huh7, SNU449 and MCF7) [ 65 ]. This can be explained by an increased cellular uptake and intracellular exposure of doxorubicin, which was observed to accumulate intracellularly where concentrations were 230 times higher than exposure concentrations [ 65 ]. This high intracellular accumulation of doxorubicin and the lack of a distinct correlation with the extracellular concentration suggests that passive diffusion is a key mechanism for the overall intracellular delivery of doxorubicin into tumour cell lines [ 65 ].…”

“…This can be explained by an increased cellular uptake and intracellular exposure of doxorubicin, which was observed to accumulate intracellularly where concentrations were 230 times higher than exposure concentrations [ 65 ]. This high intracellular accumulation of doxorubicin and the lack of a distinct correlation with the extracellular concentration suggests that passive diffusion is a key mechanism for the overall intracellular delivery of doxorubicin into tumour cell lines [ 65 ]. The high intracellular concentration of doxorubicin can be explained by the high binding and retention capacity of the drug to nuclear and mitochondrial DNA, which has been proved to be its main intracellular binding-sites in both experimental and quantitative pharmacological modelling [ 66 , 67 ].…”

A Comprehensive Evaluation of Sdox, a Promising H2S-Releasing Doxorubicin for the Treatment of Chemoresistant Tumors

“…Thus, it may be expected that the higher lipophilicity of Sdox compared to Dox confers an increased uptake within tumor cells, also in the presence of high levels of P-gp, as demonstrated previously ( Buondonno et al, 2019 ) and suggested by the higher cytotoxicity of Sdox compared to Dox in P-gp-overexpressing cells observed in the present work. On the other hand, the intracellular uptake of Dox from the solution was found to be higher than from liposomal formulation at therapeutically relevant concentrations ( Kullenberg et al, 2021 ), while low solubility warns about the need of administering Sdox-like drugs as liposomal formulations to ensure a higher efficacy ( Gazzano et al, 2019 ).…”

Specifically Targeted Transport of Plasma Membrane Transporters: From Potential Mechanisms for Regulating Cell Health or Disease to Applications

“…Traditional liposomes can enhance drug delivery to diseased tissues by altering drug metabolism and biodistribution, thereby reducing the biotoxicity of drug components in vivo. However, these liposome delivery systems are easily and rapidly cleared in the blood flow with limited efficacy [ 115 , 116 ]. Class B systems are pegylated liposomes.…”