<p>Chloroquine sensitizes MDA-MB-231 cells to osimertinib through autophagy–apoptosis crosstalk pathway</p>

Abstract

Background: Triple-negative breast cancer (TNBC) is a breast cancer that tests negative for estrogen receptor (ER), progesterone receptors, and human epidermal growth factor receptors 2 (HER2). It is aggressive and invasive in nature and lacks targeted therapy.Purpose: The EGFR is frequently overexpressed in TNBC, and the EGFR-overexpressing TNBC presumably escapes EGFR inhibitor therapy by upregulating autophagy and inhibiting apoptosis.Methods: To parse the autophagy–apoptosis crosstalk pathway as a potential targeted therapy in TNBC, the activity of an EGFR inhibitor, osimertinib, alone and in combination with an autophagy inhibitor, chloroquine, was examined in EGFR-overexpressing TNBC cell line, MDA-MB-231. The nature of interaction between both drugs at various concentrations was determined by calculating combination indexes (CI) using CompuSyn software. Temporal changes in the expression of the autophagy marker, LC3B-II, and several apoptosis signaling molecules were measured using Western blot and luminex assay with MAGPIX® after exposure to drugs. A synergistic interaction (CI <1) was identified with combinations of 4–6.5 μM osimertinib with 30–75 μM chloroquine.Results: A combination of osimertinib (6 μM) with chloroquine (30 μM) resulted in a 6-fold increase of LC3B-II relative to control compared to 2.5-fold increase for either drug alone. The caspase-3 expression increased 2-fold compared to a 0.5-fold decrease with chloroquine and 1.5-fold increase with osimertinib.Conclusion: Our results indicate that inhibition of the autophagic flux via chloroquine improves the effectiveness of osimertinib in TNBC cancer cells, warranting further investigations of this combination in vivo.

Dual Inhibition of AKT and MEK Pathways Potentiates the Anti-Cancer Effect of Gefitinib in Triple-Negative Breast Cancer Cells

“…The MSL subtype of TNBC is associated with activated EGFR signaling [ 5 ] and exhibits greater intrinsic resistance to EGFRis than the BL TNBC cells [ 25 , 30 ]. Inhibition of EGFR alone does not suppress the proliferation of TNBC cells in preclinical cell line models; however, growing evidence supports EGFR as a potential therapeutic target for TNBC treatments, especially in combination with other targeted drugs [ 3 , 25 , 30 , 33 , 37 , 123 , 124 , 125 , 126 , 127 ]. Therefore, the identification of targets in combination with EGFRis provides an alternative strategy for developing an effective TNBC therapy because EGFR-targeting drugs have been approved [ 15 , 16 ].…”

Potentiating Therapeutic Effects of Epidermal Growth Factor Receptor Inhibition in Triple-Negative Breast Cancer

“…The combination of osimertinib and chloroquine (CHQ), an autophagy and lysosome inhibitor [ 576 ], has been reported to show anticancer effects, namely a reduction in cell viability in MDA-MB-231 cells [ 426 ]. Concordantly, LC3B-II, an autophagic marker that is tightly associated with autophagosomal membranes [ 577 ], was upregulated by this combination.…”

“…Furthermore, the proapoptotic proteins, BCL2-associated agonist of cell death (BAD) [ 578 ] and active caspase-3, were increased by this combination. These results suggest that the osimertinib and CHQ combination exerts anticancer effects through autophagy–apoptosis crosstalk, but further details remain to be determined [ 426 ].…”

Compounds from diverse natural origin against triple‐negative breast cancer: A comprehensive review

“…Compared to a 0.5‐fold drop with chloroquine and a 1.5‐fold increase with osimertinib, the expression of caspase‐3 increased twofold. These findings show that chloroquine enhances the efficacy of osimertinib in TNBC cancer cells by inhibiting the autophagic flow (Fleisher et al, 2019). Gefitinib, an EGFR inhibitor, and Fingolimod, a sphingosine kinase inhibitor, were examined in conjunction to suppress tumorigenic signaling downstream of IGFBP‐3, which is highly expressed in basal‐like TNBC.…”