Potentiation of Low-Dose Doxorubicin Cytotoxicity by Affecting P-Glycoprotein through Caryophyllane Sesquiterpenes in HepG2 Cells: an in Vitro and in Silico Study.

Di Sotto Di Sotto,Di Giacomo Di Giacomo,Eufemi Eufemi,Irannejad Irannejad,Mancinelli Mancinelli,Mazzanti Mazzanti,Mammola Mammola,Altieri Altieri,Abete Abete

doi:10.3390/ijms21020633

Abstract

Doxorubicin represents a valuable choice for different cancers, although the severe side effects occurring at the high effective dose limits its clinical use. In the present study, potential strategies to potentiate low-dose doxorubicin efficacy, including a metronomic schedule, characterized by a short and repeated exposure to the anticancer drug, and the combination with the natural chemosensitizing sesquiterpenes β-caryophyllene and β-caryophyllene oxide, were assessed in human hepatoma HepG2 cells. The involvement of P-glycoprotein (P-gp) in the HepG2–chemosensitization to doxorubicin was evaluated. Also, the direct interaction of caryophyllene sesquiterpenes with P-gp was characterized by molecular docking and dynamic simulation studies. A metronomic schedule allowed us to enhance the low-dose doxorubicin cytotoxicity and the combination with caryophyllane sesquiterpenes further potentiated this effect. Also, an increased intracellular accumulation of doxorubicin and rhodamine 123 induced by caryophyllane sesquiterpenes was found, thus suggesting their interference with P-gp function. A lowered expression of P-gp induced by the combinations, with respect to doxorubicin alone, was observed too. Docking studies found that the binding site of caryophyllane sesquiterpene was next to the ATP binding domain of P-gp and that β-caryophyllene possessed the stronger binding affinity and higher inhibition potential calculated by MM-PBSA. Present findings strengthen our hypothesis about the potential chemosensitizing power of caryophyllane sesquiterpenes and suggest that combining a chemosensitizer and a metronomic schedule can represent a suitable strategy to overcome drawbacks of doxorubicin chemotherapy while exploiting its powerful activity.

Highlights

Doxorubicin is an anthracycline antibiotic widely used in the therapy of different cancer types due to its effective cancer-killing potential, mediated by multiple cytotoxic mechanisms involving DNA-damage, blocking of cancer cell growth and increase of intracellular oxidative stress, which in turn lead to destruction of cell structures and cell death [1]
Docking studies found that the binding site of caryophyllane sesquiterpene was next to the ATP binding domain of P-gp and that β-caryophyllene possessed the stronger binding affinity and higher inhibition potential calculated by MM-PBSA
The present study demonstrated that caryophyllane sesquiterpenes are able to potentiate the cytotoxicity of low-dose doxorubicin both under standard and metronomic schedules

Summary

Introduction

Doxorubicin is an anthracycline antibiotic widely used in the therapy of different cancer types due to its effective cancer-killing potential, mediated by multiple cytotoxic mechanisms involving DNA-damage, blocking of cancer cell growth and increase of intracellular oxidative stress, which in turn lead to destruction of cell structures and cell death [1]. It has been suggested to be a valuable chemotherapeutic choice for liver cancer, if used through advanced pharmaceutical forms or under polytherapy regimens [2], sorafenib remains the only approved drug [3]. Severe dose-dependent side effects on normal tissues, cardiotoxicity and myelosuppression, and multidrug resistance development occur, lowering tolerability and efficacy of doxorubicin chemotherapy [5]. Sorafenib is the only approved drug for liver cancer for the early stages of HCC, doxorubicin has been suggested to be a valuable chemotherapeutic choice for liver cancer if used through advanced pharmaceutical forms or under polytherapy regimens [2,6]

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Discussion

Conclusion