Inhibition Of Human Nasopharyngeal Carcinoma Cell Growth And Induction Of Cell Cycle Arrest By Garcinone

Nasopharyngeal carcinoma (NPC) is one of the common head and neck malignancies. Radiotherapy and chemotherapy are the standard treatments for NPC. Garcinone, a natural compound isolated from Garcinia oblongifolia Champ, is a xanthone derivative has been shown to have potential cytotoxic effects on certain cancer types. However, there is a limited study on its effects on NPC cells and the mechanisms of these effects remain unknown. In this study, we firstly found that compared with the controls, garcinone significantly inhibited cell viability of human NPC cell lines CNE1, CNE2, HK1, and HONE1. This inhibition was in a time- and dose-dependent manner. Then, flow cytometry analysis was performed on cell cycle analysis. We observed that garcinone arrested cell cycle at S phase. With 10μM of high-dose garcinone treatment, the cells exhibited necrotic morphology changes including cell swelling, rough endoplasmic reticulum (ER) degranulation, ER dilatation, mitochondria swelling, and vacuolar degeneration. Finally, we found that garcinone stimulated the expression level of ATR and 4E-BP1, while efficiently inhibited the expression level of Cyclin B1, Cyclin D1, Cyclin E2, cdc2, CDK7, and Stat3. Collectively, the ability of garcinone to inhibit NPC in vitro suggested that garcinone might be a novel agent for the management of NPC.Objective:To investigate whether Garcinone, a natural product extracted from Garcinia oblongifolia Champ, inhibits the growth of NPC cells, in order to develop new treatment for NPC.Methods:1. We used MTS assay to evaluate the effect of Garcinone on four NPC cells (CNE1、CNE2、HK1 and HONE1).2. Apoptosis and cell cycle test were used to detect the effect of Garcinone onNPC cells.3. Western blot was used to determine the proteins expression of apoptosis, cell cycle and autophagy, and to discover signaling pathways.4. Colony formation assay was used to observe the change of NPC cells.5. Electron microscope was used to observe the changes of organelles.Results:Cell proliferation assay showed that the growth of four NPC cells was inhibited after Garcinone treatment marmer, in dose-and time-dependent manner. NPC cells were apperantly arrested at S/G2phase after Garcinone treatments, measured by Flow Cytometry. However, in apoptosis analysis, there was no significanty changed between Garcinone group and control group. The expression of cyclins changed after treated with Garcinone. The colony formation rate of NCP cells was significantly decreased in Garcinone group, compared with control group. The obvious mitochondria swelling and autophagosome can be observed in Garcinone group compared with the control group by electron microscope.Conclusions:Garcinone can effectively suppress proliferation of NPC cells and arrest cell in S phase. Garcinone decreases the expression of Stat3 and reduce the colony formation rate of NPC cells. Besides, vacuolar degeneration structure and autophagosome will appear in cells after treated with Garcinone, resulting in apoptosis.