A Synergistic pH-Responsive Serum Albumin-Based Drug Delivery System Loaded with Doxorubicin and Pentacyclic Triterpene Betulinic Acid for Potential Treatment of NSCLC

Abstract

Nanosized drug delivery systems (DDS) have been studied as a novel strategy against cancer due to their potential to simultaneously decrease drug inactivation and systemic toxicity and increase passive and/or active drug accumulation within the tumor(s). Triterpenes are plant-derived compounds with interesting therapeutic properties. Betulinic acid (BeA) is a pentacyclic triterpene that has great cytotoxic activity against different cancer types. Herein, we developed a nanosized protein-based DDS of bovine serum albumin (BSA) as the drug carrier combining two compounds, doxorubicin (Dox) and the triterpene BeA, using an oil-water-like micro-emulsion method. We used spectrophotometric assays to determine protein and drug concentrations in the DDS. The biophysical properties of these DDS were characterized using dynamic light scattering (DLS) and circular dichroism (CD) spectroscopy, confirming nanoparticle (NP) formation and drug loading into the protein structure, respectively. The encapsulation efficiency was 77% for Dox and 18% for BeA. More than 50% of both drugs were released within 24 h at pH 6.8, while less drug was released at pH 7.4 in this period. Co-incubation viability assays of Dox and BeA alone for 24 h demonstrated synergistic cytotoxic activity in the low μM range against non-small-cell lung carcinoma (NSCLC) A549 cells. Viability assays of the BSA-(Dox+BeA) DDS demonstrated a higher synergistic cytotoxic activity than the two drugs with no carrier. Moreover, confocal microscopy analysis confirmed the cellular internalization of the DDS and the accumulation of the Dox in the nucleus. We determined the mechanism of action of the BSA-(Dox+BeA) DDS, confirming S-phase cell cycle arrest, DNA damage, caspase cascade activation, and downregulation of epidermal growth factor receptor (EGFR) expression. This DDS has the potential to synergistically maximize the therapeutic effect of Dox and diminish chemoresistance induced by EGFR expression using a natural triterpene against NSCLC.

Unraveling the Influence of Six Lupane-, Oleanane-, and Ursane- type Pentacyclic Triterpenes' Structure-Activity Relationship on Non-Small Lung Adenocarcinoma Cells

“…In summary, BeA emerge as the triterpenes exerting the most widespread influence on several key pathways to induce mitochondrial-based apoptosis with the lowest IC50, a TI > 1 and inhibit the chemoresistance-related genes STAT3 and PDL1. Furthermore, we previously demonstrated that BeA synergizes with doxorubicin to increase the effectivity of this drug in A549 cells [45]. These findings collectively indicate that triterpenes impact different pathways depending on the substituents of their rings.…”

Unraveling the Impact of Six Pentacyclic Triterpenes Regulating Metabolic Pathways on Lung Carcinoma Cells

“…On the other hand, selectivity of BeA could be increased by its encapsulation into a targeted drug delivery system (DDS). Thus, we previously loaded BeA in a protein-based DDS, demonstrating that BeA was synergized with doxorubicin chemotherapy in A549 cells [ 50 ].…”

Drug Delivery Systems of Betulin and Its Derivatives: An Overview

“…Research has also attempted to clarify the mechanism of action of individual derivatives. Understanding the interaction between the active molecular component and the therapeutic target will facilitate the development of more effective therapeutic systems [ 83 , 85 , 92 , 94 , 95 , 148 , 149 ]. Further progress in these fields is expected in the future.…”

“…Moreover, cellular internalization of BSA-(Dox+BA) and the accumulation of the Dox in the nucleus were confirmed. The mechanism of action of BSA-(Dox+BA) relied on S-phase cell cycle arrest, DNA damage, caspase cascade activation, and downregulation of epidermal growth factor receptor (EGFR) expression [ 83 ].…”