Effect of gedunin on cell proliferation and apoptosis in skin melanoma cells A431 via the PI3K/JNK signaling pathway.

Abstract

Melanoma is an aggressive skin malignancy with rapid metastasis and high morbidity. Gedunin (GN) is a tetranortriterpenoid belonging to the Meliaceae family, described for its anticancer, antiproliferative and apoptotic properties. In the present study, we investigated the effect of GN on A431 melanoma cell proliferation and apoptosis. The inflammatory proteins (tumor necrosis factor alpha (TNF-α), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), cycloxygenase 2 (COX-2), inducible nitric oxide synthase (iNOS), and interleukin 6 (IL-6)) apoptosis-related proteins, such as Bax, Bcl-2 and caspase-3, and alterations in the PI3K/JNK and p38 pathways in A431 cells after GN treatment were examined. The cytotoxicity assay and cell apoptosis of GN activity on A431 cells were assessed using MTT assay, acridine orange/ethidium bromide (AO/EB), DAPI (4',6-diamidino-2-phenylindole), propidium iodide (PI), enzyme-linked immunosorbent assay (ELISA), reverse transcription polymerase chain reaction (RT-PCR) and western blot analyses. The findings demonstrated that GN (10 and 15 μM/mL) inhibits the growth of melanoma cells, triggers apoptosis by enhancing Bax and caspase, and reduces Bcl-2, cyclin-D1, c-myc, and survivin in a concentration-reliant manner. Additionally, GN attenuated the protein expression of inflammatory proteins (TNF-α, NF-κB, COX-2, iNOS, and IL-6) and the cell proliferative PI3K/JNK/p38 signaling pathway. Due to the imbalance in the Bax/Bcl-2 ratio, apoptosis is promoted, and the caspase cascade and Cyt-c are activated. This led us to conclude that GN treatment inhibited Bcl-2, cyclin-D1, c-myc, and survivin activity through the TNF-α/NF-κB and PI3K/JNK/p38 signaling pathways, further preventing the proliferation and stimulation of apoptosis, which contributes to growth arrest in melanoma cells. Gedunin has been shown to promote melanoma cell death in vitro, suggesting that it could be used as a future treatment for malignant melanoma. Our findings suggested that GN might be applied as a preventative measure in the management of skin melanoma cells.