Gefitinib‑mediated apoptosis is enhanced via inhibition of autophagy by chloroquine diphosphate in cutaneous squamous cell carcinoma cells

Abstract

The development of cutaneous squamous cell carcinoma (cSCC) is associated with activation of the epidermal growth factor receptor (EGFR). EGFR-targeting presents a promising strategy for improving therapeutic efficacy. However, recent studies have suggested that tumours overexpressing EGFR depend on autophagy for survival and exhibit resistance to EGFR-targeting drugs. Chloroquine diphosphate (CQ), an autophagy inhibitor that may enhance the cytocidal effect of gefitinib against cSCC, was used in the present study. Cytotoxicity assays were performed to determine the half-maximal inhibitory concentration values of gefitinib and CQ in A431 cells. Drug interaction was analysed using CompuSyn software, which also determined combination index and dose reduction index values. Apoptosis and autophagy of A431 cells were investigated via flow cytometry, western blotting analyses, acridine orange/ethidium bromide staining and monodansylcadaverine staining. Suppression of autophagy by CQ, which was demonstrated by an alteration in microtubule associated protein 1 light chain 3-B in CQ pre-treated A431 cells, significantly enhanced cell apoptosis, which suggested that gefitinib-induced autophagy is cytoprotective. Thus, CQ was demonstrated to exhibit a synergistic apoptotic effect when used in combination with gefitinib during cSCC therapy. Further in vivo investigations are required to confirm the results of the present study.

Potential Therapeutic Approaches through Modulating the Autophagy Process for Skin Barrier Dysfunction

“…The blockade of autophagy by chloroquine was demonstrated by the increased cleavage of caspase-3 and the accumulation of LC3-II and SQSTM1 (p62). A similar study was performed by Wang's group and concluded that chloroquine exhibits a synergetic apoptotic effect mediated by gefitinib in SSCC cells [98]. The suppression of autophagy by chloroquine was demonstrated by the alteration of LC3-II.…”

Improving the Efficacy of EGFR Inhibitors by Topical Treatment of Cutaneous Squamous Cell Carcinoma with miR-634 Ointment

“…Various cytoprotective cell survival processes, including anti-apoptosis signaling, antioxidant scavenging, autophagy, and glutaminolysis, are involved in attenuating TKI-induced cytotoxicity. 16 , 17 , 18 , 19 , 20 , 21 Our current and previous studies demonstrated that miR-634 can directly and concurrently target multiple genes associated with these cytoprotective processes, including ASCT2 in glutaminolysis. Therefore, we propose that topical treatment with miR-634 ointment is a reasonable strategy for maximizing the efficacy of TKI-based therapy in cSCC through the concurrent modulation of multiple cytoprotective processes ( Figure 5 F).…”

“… 3 , 12 , 13 , 14 , 15 Various cytoprotective processes, including glutaminolysis, are involved in attenuating TKI-induced cytotoxicity. 16 , 17 , 18 , 19 Hence, we examined whether overexpression of miR-634 enhances TKI-induced cytotoxicity. When A431 cells were transfected with increasing doses (1.0–10 nM) of miR-634 and simultaneously treated with gefitinib (1–30 μM), capase-3/7 activity gradually increased in a dose-dependent manner compared with cells treated with gefitinib only ( Figure 4 A).…”

“… 14 TKI-induced cytotoxicity is attenuated by various cytoprotective cell survival processes, including anti-apoptosis signaling, antioxidant scavenging, and autophagy. 16 , 17 , 18 , 19 Furthermore, glutaminolysis, a metabolic process involving glutamine utilization that produces ATP as an energy source and glutathione (GSH) as a reactive oxygen species (ROS) scavenger, is also involved in attenuating TKI-induced cytotoxicity. 20 , 21 Therefore, negatively modulating these cytoprotective processes may be a reasonable strategy for improving the efficacy of EGFR TKIs in cSCC.…”

Chloroquine diphosphate suppresses liver cancer via inducing apoptosis in Wistar rats using interventional therapy

“…It has also been reported that CQ exerts anticancer effects on several types of cancer. Wang et al (29) confirmed that CQ may enhance gefitinib-mediated apoptosis of cutaneous squamous cell carcinoma cells via inducing autophagy. Additionally, Wei et al (15) demonstrated that CQ was involved in the suppression of pancreatic cancer via regulating the expression profile of circular RNAs, long non-coding RNAs, microRNAs and mRNAs.…”