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Introduction
Human esophageal cancer is a commonly diagnosed disease worldwide, with an increasing incidence estimated at more than 450,000 new cases each year (1). Two important types of human esophageal cancer have been identified, including squamous cell carcinoma and adenocarcinoma, in which, esophageal squamous cell carcinoma has a higher prevalence in China (2). Several therapeutic approaches have been developed for esophageal cancer in recent decades, including endoscopic resection and surgery; however, these approaches show some efficacy only during the early stages of esophageal cancer (3,4). Radiotherapy and chemotherapy are more commonly used for advanced stages, but their efficacy remains unsatisfactory due to the development of therapeutic resistance and unavoidable side effects (4,5). Recently, numerous studies have demonstrated that compounds isolated from traditional Chinese medicines, such as osthole, bufadienolides, matrine, and the ajoene analogue BisPMB, exhibit anti-esophageal cancer activity through the induction of apoptosis, cell cycle arrest and endoplasmic reticulum stress (6–9). Consequently, the development of new treatment agents from traditional Chinese medicine is becoming a promising strategy for the treatment of esophageal cancer.
Dracorhodin perchlorate (DP) (Fig. 1A) is a synthetic analogue of the anthocyanin red pigment dracorhodin, which is extracted from exudates of the fruit of Daemonorops draco, also known as ‘dragon's blood’ in traditional Chinese medicine (10,11). It has been reported to exert a variety of physiological and pharmacological effects, such as antimicrobial and antifungal activity and promotion of wound healing (11–14). Recently, there has been increasing interest in the anticancer properties of DP, which have been demonstrated in several studies undertaken on various types of malignant cells. For example, DP was reported to induce apoptosis in human gastric adenocarcinoma through inactivation of the AKT/FOXO3a and NF-κB signaling pathways (15) and through activation of the p38/JNK MAPK signaling pathways in human melanoma cells (16). In addition to apoptosis, DP has also been shown to induce cell cycle arrest in various types of cancer cells (15,17). However, the effect of DP on ESCC remains unknown, and the molecular mechanisms underlying the anticancer properties of DP warrant further investigation.
In our previous study, DP induced intrinsic apoptosis and G1 phase arrest and upregulated p53 in human lung squamous carcinoma cells (18). In the present study, the potential antitumor effects of DP were investigated on...