Isocorydine inhibits the proliferation of human endometrial carcinoma HEC-1B cells by downregulating the Ras/MEK/ERK signaling pathway

Abstract

Objective: Isocorydine (ICD), an aporphine alkaloid, plays a role in anticancer activity that is still being evaluated. However, the exact function and mechanism of ICD in endometrial carcinoma is largely unknown. Methods: MTT, flow cytometry, western blot, immunofluorescence, RT-PCR and ELISA were used in this research. Results: In our study we showed that ICD inhibited endometrial carcinoma HEC-1B cell proliferation at certain times and concentrations. Simultaneously, ICD induced HEC-1B cells apoptosis. Further investigation indicated that ICD reduced the phosphorylation protein levels of c-Raf (rapidly accelerated fibrosarcoma), MEK1/2 (MAPK/Erk kinase) and ERK1/2 (extracellular regulated protein kinase). Moreover, a cell immunofluorescence assay confirmed that ICD reduced intracellular expression of Ras and then promoted FOXO3 (forkhead box O3) nuclear localization to furtherly increase the mRNA level of Bim and p27Kip1. Additionally, an enzyme-linked immunosorbent assay (ELISA) revealed that ICD inhibited the production of EGF (epidermal growth factor) and PDGF (Platelet-Derived Growth Factor), which indicated that ICD indirectly inhibited the activation of the Ras/MEK/ERK signaling pathway at the ligand level. Conclusion: Taken together, these data suggest for the first time that ICD inhibits cell proliferation and induces cell apoptosis in endometrial carcinoma through suppressing Ras/MEK/ERK signaling, which may provide a theoretical foundation to the application of ICD for the treatment of human endometrial carcinoma.