Shikonin-induced necroptosis is enhanced by the inhibition of autophagy in non-small cell lung cancer cells

Abstract

BackgroundShikonin, a natural naphthoquinone pigment purified from Lithospermum erythrorhizon, induces necroptosis in various cancer types, but the mechanisms underlying the anticancer activity of shikonin in lung cancer are not fully understood. This study was designed to clarify whether shikonin causes necroptosis in non-small cell lung cancer (NSCLC) cells and to investigate the mechanism of action.MethodsMultiplex and caspase 8 assays were used to analyze effect of shikonin on A549 cells. Cytometry with annexin V/PI staining and MTT assays were used to analyze the mode of cell death. Western blotting was used to determine the effect of shikonin-induced necroptosis and autophagy. Xenograft and orthotopic models with A549 cells were used to evaluate the anti-tumor effect of shikonin in vivo.ResultsMost of the cell death induced by shikonin could be rescued by the specific necroptosis inhibitor necrostatin-1, but not by the general caspase inhibitor Z-VAD-FMK. Tumor growth was significantly lower in animals treated with shikonin than in the control group. Shikonin also increased RIP1 protein expression in tumor tissues. Autophagy inhibitors, including methyladenine (3-MA), ATG5 siRNA, and bafilomycin A, enhanced shikonin-induced necroptosis, whereas RIP1 siRNA had no effect on the apoptotic potential of shikonin.ConclusionsOur data indicated that shikonin treatment induced necroptosis and autophagy in NSCLC cells. In addition, the inhibition of shikonin-induced autophagy enhanced necroptosis, suggesting that shikonin could be a novel therapeutic strategy against NSCLC.

Naturally occurring anti-cancer compounds: shining from Chinese herbal medicine

“…Shikonin (Fig. 2) is an active naphthoquinone, which is derived from the dried root of Lithospermum erythrorhizon, Arnebia euchroma and Arnebia guttata, and it possesses anti-oxidative, anti-inflammatory, and anti-cancer activities [591][592][593][594]. It is effective in treating different kinds of cancers, including breast, prostate, ovarian and thyroid cancers, Ewing sarcoma, and myelomonocytic lymphoma [595][596][597][598][599][600].…”

“…It is effective in treating different kinds of cancers, including breast, prostate, ovarian and thyroid cancers, Ewing sarcoma, and myelomonocytic lymphoma [595][596][597][598][599][600]. Shikonin exerts anti-cancer effects mainly by inducing apoptosis, necroptosis, autophagy, cell cycle arrest, and by inhibiting cell proliferation, growth and metastasis [593,601,602].…”

“…Shikonin is reported to inhibit cell growth by inducing cell cycle arrest and promoting apoptosis in human NSCLC A549, gallbladder cancer NOZ and EHGB-1, esophageal cancer EC109, and epidermoid carcinoma A-431 cells [601,[603][604][605]. It can also induce necroptosis via autophagy inhibition in human NSCLC A549 cells [593], and through ROS overproduction in human nasopharyngeal carcinoma 5-8F, and glioma SHG-44, U87 and U251 cells [606,607]. Moreover, shikonin induces autophagy in human melanoma A375, pancreatic cancer BxPC-3, and hepatocellular carcinoma Bel-7402 and Huh7 cells [608][609][610].…”

<p>Experimental Study of Hepatocellular Carcinoma Treatment by Shikonin Through Regulating PKM2</p>

“…Shikonin (SK), which is isolated from Lithospermum erythrorhizon, has been reported to possess various therapeutic effects, including anti-inflammation, 12,13 antiischemia/reperfusion injury, 14,15 and anti-cancer. 16,17 SK has minimal harm to normal cells and has anti-cancer effects on various tumor cells. [18][19][20] Zhou et al 21 showed that SK induces glioma cell necroptosis by increasing intracellular ROS.…”

Synergistic Cytotoxicity Of Shikonin‐Silver Nanoparticles As An Opportunity For Lung Cancer

“…Shikonin, a phytochemical naphthoquinone isolated from the roots of the Chinese herbs Lithospermum erythrorhizon, has a significant cytotoxic vigor, suppressing of tumor cell growth and inducing apoptosis in several lines of cancer cells both in vivo and in vitro . Shikonin has been shown to kill certain cancer cells such non‐small cell lung cancer (NSCLC) cells through a number of possible mechanisms and could bypass cancer drug resistance …”