The Histone Deacetylase Inhibitor Droxinostat Sensitizes Human Colon Cancer Cells To Apoptosis And Molecular Mechanisms

Colorectal cancer(CRC)is one of the most common digestive tract malignant tumors worldwide.It is well known that 5-Fluorouracil(5-FU)–based chemotherapy regimens remain the standard treatment for CRC in both the adjuvant and advanced disease settings and improves overall survival,while,resistance to chemotherapy is still a major reason for treatment failure in colon cancer.Novel and efficacious therapeutic agents and strategies are thus urgently needed for treatment of colon cancer.Recently,histone deacetylases inhibitors(HDACIs)are becoming a promising new target in cancer therapy.Droxinostat is one of HADCIs with promising anticancer activity.It have been demonstrated that several Droxinostat can sensitizes malignant cells to several death receptor ligands.Reactive Oxygen Species(ROS)is associated with some risk factors related to cancers.ROS activates the transcription factors NF-κB,AP-1,HIF-1α and STAT3 and others.These ROS-mediated transcription factors control the expression of genes involved in inflammation,cell transformation,tumor cell death,survival,proliferation,invasion,angiogenesis and metastasis.The production of ROS is related to tumor progression via DNA damage,protein oxidation and lipid peroxidation.Meanwhile,ROS plays a role in cell signaling pathways.ROS can suppress tumor progression because of induction of apoptosis.Numerous agents have been shown to induce ROS andapoptosis in various cancer types.In this study,we hypothesized that Droxinostat treatment inhibite the growth a of human colon cancer cells and increase the sensitivity of human colon cancer cells to apoptosis.To test this possibility,we investigated the effects of Droxinostat on human colon cancer cell lines and further explored the molecular mechanisms.Methods: First of all,to determine the number of planting,cells were grown in plates with different number of cells without agents.Cell viability was measured by MTT assay with Droxinostat,Tubastatin A and PCI-34051 treatmented cells.IC50 of Droxinostat was calculated using Graphpad.Clonogenic assay was used to measured the colony forming ability.Apoptosis inhibitor Z-VAD-FMK was utilized prior to Droxinostat treatment for 2h,then flow cytometry was used to determine the apoptosis of colon cancer cells in the presence or absence of Droxinostat.Meanwhile,antioxidant GT3 was utilized prior to Droxinostat treatment for 2h,and then the level of intracellular ROS in colon cancer cells with or without Droxinostat treatment were measured by flow cytometry.Results: Droxinostat can inhibite the growth a of human colon cancer cells through induction of cellular apoptosis and accumulation of ROS in colon cancer cells.Z-VAD-FMK can block apopotosis induced by Droxinostat.GT3 could partially decrease ROS levels triggered by Droxinostat.Conclusion: The results indicate that Droxinostat effectively reduced cell viability,induced apoptosis in colon cancer cells.Droxinostat also induced accumulation of intracellular ROS.Moreover,Z-VAD-FMK overcame the Droxinostat-induced apoptosis.Taken together,Droxinostat induced colon cancer cells to apoptosis through induction of ROS production and have therapeutic potential in the treatment of colon cancer.