Physapruin A Induces Reactive Oxygen Species to Trigger Cytoprotective Autophagy of Breast Cancer Cells

Abstract

Physalis peruviana-derived physapruin A (PHA) is a potent compound that selectively generates reactive oxygen species (ROS) and induces cancer cell death. Autophagy, a cellular self-clearance pathway, can be induced by ROS and plays a dual role in cancer cell death. However, the role of autophagy in PHA-treated cancer cells is not understood. Our study initially showed that autophagy inhibitors such as bafilomycin A1 enhanced the cytotoxic effects of PHA in breast cancer cell lines, including MCF7 and MDA-MB-231. PHA treatment decreased the p62 protein level and increased LC3-II flux. PHA increased the fluorescence intensity of DAPGreen and DALGreen, which are used to reflect the formation of autophagosome/autolysosome and autolysosome, respectively. ROS scavenger N-acetylcysteine (NAC) decreased PHA-elevated autophagy activity, implying that PHA-induced ROS may be required for autophagy induction in breast cancer cells. Moreover, the autophagy inhibitor increased ROS levels and enhanced PHA-elevated ROS levels, while NAC scavenges the produced ROS resulting from PHA and autophagy inhibitor. In addition, the autophagy inhibitor elevated the PHA-induced proportion of annexin V/7-aminoactinmycin D and cleavage of caspase-3/8/9 and poly (ADP-ribose) polymerase. In contrast, NAC and apoptosis inhibitor Z-VAD-FMK blocked the proportion of annexin V/7-aminoactinmycin D and the activation of caspases. Taken together, PHA induced ROS to promote autophagy, which might play an antioxidant and anti-apoptotic role in breast cancer cells.

MAP3K11 facilitates autophagy activity and is correlated with malignancy of oral squamous cell carcinoma

“…The Hela cells were seeded on coated coverslips (0.5% gelatin and 0.05% chromium potassium sulfate) and transfected with siRNA for 48 h. The cells were then transfected with PK‐hLC3 expression vector encoding pHluorin‐mKate2‐tagged human MAP1LC3 (Tanida et al, 2014) for 24 h. The green and far‐red fluorescent proteins were imaged under an Olympus FluoView FV1000 confocal laser scanning microscope with excitation 488 (green)/588 nm (far‐red) and emission 520 (green)/633 nm (far‐red). For autophagy staining assay, oral cancer cells were stained with wither autophagosome dye (DAPGreen, 0.1 μM) or autolysosome dye (DALGreen, 0.5 μM) (Dojindo) for 30 min (Yu et al, 2022). The green fluorescence was imaged under an Olympus FluoView FV1000 confocal laser scanning microscope.…”

“…The green and far-red fluorescent proteins were imaged under an Olympus FluoView FV1000 confocal laser scanning microscope with excitation 488 (green)/588 nm (far-red) and emission 520 (green)/633 nm (far-red). For autophagy staining assay, oral cancer cells were stained with wither autophagosome dye (DAPGreen, 0.1 μM) or autolysosome dye (DALGreen, 0.5 μM) (Dojindo) for 30 min (Yu et al, 2022). The green fluorescence was imaged under an Olympus FluoView FV1000 confocal laser scanning microscope.…”

Linagliptin in combination with insulin suppresses apoptotic unfolded protein response in ovaries exposed to type 1 diabetes

“…Endoplasmic reticulum (ER) stress occurs due to the accumulation of unfolded proteins in the ER that can be caused by various physiological and pathological conditions, including oxidative stress and inflammation 11,12 . In a study, it was shown that Physapruin A, which has an antiproliferative effect, exhibited ER stress‐inducing function to promote the proliferation and apoptosis of breast cancer cells containing oxidative stress 13 …”