Assessment of Betulinic Acid Cytotoxicity and Mitochondrial Metabolism Impairment in a Human Melanoma Cell Line.

Dorina Coricovac,Crina Petean,Iulia Pinzaru,Mirela Danina Muntean,Oana-Maria Aburel,Codruta Soica,Brigitha Vlaicu,George Andrei Draghici,Alexandra Mioc,Ioana Macasoi,Madalina Boruga,Cristina Adriana Dehelean

doi:10.3390/ijms22094870

Abstract

Melanoma represents one of the most aggressive and drug resistant skin cancers with poor prognosis in its advanced stages. Despite the increasing number of targeted therapies, novel approaches are needed to counteract both therapeutic resistance and the side effects of classic therapy. Betulinic acid (BA) is a bioactive phytocompound that has been reported to induce apoptosis in several types of cancers including melanomas; however, its effects on mitochondrial bioenergetics are less investigated. The present study performed in A375 human melanoma cells was aimed to characterize the effects of BA on mitochondrial bioenergetics and cellular behavior. BA demonstrated a dose-dependent inhibitory effect in both mitochondrial respiration and glycolysis in A375 melanoma cells and at sub-toxic concentrations (10 μM) induced mitochondrial dysfunction by eliciting a decrease in the mitochondrial membrane potential and changes in mitochondria morphology and localization. In addition, BA triggered a dose-dependent cytotoxic effect characterized by apoptotic features: morphological alterations (nuclear fragmentation, apoptotic bodies) and the upregulation of pro-apoptotic markers mRNA expression (Bax, Bad and Bak). BA represents a viable therapeutic option via a complex modulatory effect on mitochondrial metabolism that might be useful in advanced melanoma or as reliable strategy to counteract resistance to standard therapy.

Highlights

Our data showed that the stimulation of A375 cells with cells, we further evaluated the key parameters of mitochondrial respiration in permeaBA (10 μM) for 24 h determined a significant decrease of basal respiration rates—leak bilized treated optimal concentration of betulinic acid (BA)
This study was aimed at gathering novel insights regarding the effects of betulinic acid on mitochondrial bioenergetics in human melanoma cells, as a metabolism-driven approach to fully understand the antitumoral property of this bioactive phytocompound
Our results indicate that betulinic acid elicited a dose-dependent inhibitory effect on both mitochondrial respiration and glycolysis in A375 human melanoma cells

Summary

Introduction

Despite the current available therapies and the progress recorded in melanoma treatment and diagnostic tools (targeted therapies for BRAF-mutated melanomas—vemurafenib, dabrafenib; immunotherapy—ipilimumab, nivolumab, pembrolizumab; and combined therapies), invasive melanoma remains the primary cause of skin cancer deaths and a continuous increment of melanoma incidence was recorded worldwide, even though the mortality rates decreased in the latest years [5] All these facts suggest an urgent need for improvement of existing methods for melanoma prevention and protection, as well as to discover new diagnostic markers and innovative therapies that will bypass the resistance of melanoma cells and reduce the side effects of current therapies [6]. An innovative and feasible strategy for melanoma treatment consists in understanding the tumor cellular energetic metabolism, mainly the role of mitochondria in melanoma, a topic of great interest in recent years

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