Bufalin suppresses esophageal squamous cell carcinoma progression by activating the PIAS3/STAT3 signaling pathway

BACKGROUND: Esophageal cancer, especially esophageal squamous cell carcinoma (ESCC), is a common malignant tumor of the digestive tract. Bufalin is an effective anti-tumor compound. However, little is known about the regulatory mechanisms of Bufalin in ESCC. To investigate the effect and molecular mechanism of Bufalin on the proliferation, migration and invasion of ESCC cells will provide a more reliable basis for the application of Bufalin in clinical tumor therapy. METHODS: First, the half-inhibitory concentration (IC50) of Bufalin was evaluated by Cell Counting Kit-8 (CCK-8) assays. In vitro, the effects of Bufalin on the proliferation of the ECA109 cells was measured using CCK-8 and 5-ethynyl-2'-deoxyuridine assays. Wound-healing and transwell assays were used to evaluate the effects of Bufalin on the migration and invasion of the ECA109 cells. Further, to determine the mechanisms underlying the Bufalin-mediated suppression of cell progression in ESCC, total RNA was extracted from negative control (NC) and Bufalin treated cells to perform RNA-sequencing (RNA-seq) to screen for abnormally expressed genes. In vivo, the ECA 109 cells were subcutaneously injected into BALB/c nude mice to determine the effects of Bufalin on tumor cell proliferation. The protein inhibitor of activated signal transducer and activator of transcription 3 (PIAS3), signal transducer and activator of transcription 3 (STAT3), and phosphorylated STAT3 (p-STAT3) protein expression levels in the ECA109 cells were detected by Western blot. RESULTS: The CCK-8 assays showed that the IC50 of Bufalin was 200 nM. The proliferation, migration, and invasion ability of the ECA109 cells was significantly inhibited in the Bufalin group in a concentration-dependent manner. In vivo, the Xenograft tumor model showed that Bufalin decreased the tumor volume and weight of the subcutaneous tumors. The RNA-seq results showed that the expression of PIAS3 was upregulated in the Bufalin group. Additionally, down-regulation of PIAS3 decreased the inhibition of STAT3, thereby increasing p-STAT3 expression. Finally, PIAS3 knockdown reversed the inhibitory effects of Bufalin on the proliferation, migration, and invasion of the ECA109 cells. CONCLUSIONS: Bufalin may inhibit the proliferation, migration, and invasion of the ECA109 cells through the PIAS3/STAT3 signaling pathway.