Xylopine Induces Oxidative Stress and Causes G₂/M Phase Arrest, Triggering Caspase‐Mediated Apoptosis by p53‐Independent Pathway in HCT116 Cells

Abstract

Xylopine is an aporphine alkaloid that has cytotoxic activity to cancer cells. In this study, the underlying mechanism of xylopine cytotoxicity was assessed in human colon carcinoma HCT116 cells. Xylopine displayed potent cytotoxicity in different cancer cell lines in monolayer cultures and in a 3D model of cancer multicellular spheroids formed from HCT116 cells. Typical morphology of apoptosis, cell cycle arrest in the G2/M phase, increased internucleosomal DNA fragmentation, loss of the mitochondrial transmembrane potential, and increased phosphatidylserine externalization and caspase-3 activation were observed in xylopine-treated HCT116 cells. Moreover, pretreatment with a caspase-3 inhibitor (Z-DEVD-FMK), but not with a p53 inhibitor (cyclic pifithrin-α), reduced xylopine-induced apoptosis, indicating induction of caspase-mediated apoptosis by the p53-independent pathway. Treatment with xylopine also caused an increase in the production of reactive oxygen/nitrogen species (ROS/RNS), including hydrogen peroxide and nitric oxide, but not superoxide anion, and reduced glutathione levels were decreased in xylopine-treated HCT116 cells. Application of the antioxidant N-acetylcysteine reduced the ROS levels and xylopine-induced apoptosis, indicating activation of ROS-mediated apoptosis pathway. In conclusion, xylopine has potent cytotoxicity to different cancer cell lines and is able to induce oxidative stress and G2/M phase arrest, triggering caspase-mediated apoptosis by the p53-independent pathway in HCT116 cells.

A novel platinum complex containing a piplartine derivative exhibits enhanced cytotoxicity, causes oxidative stress and triggers apoptotic cell death by ERK/p38 pathway in human acute promyelocytic leukemia HL-60 cells

“…The alamar blue assay was used to quantify the cell viability and was performed following the procedure that was previously described [38] , [39] , [40] . Negative controls received the vehicle that was used for diluting the compound tested.…”

Ru(II)-Thymine Complex Causes Cell Growth Inhibition and Induction of Caspase-Mediated Apoptosis in Human Promyelocytic Leukemia HL-60 Cells

“…The cell lines that were used in this study were obtained from the American Type Culture Collection (ATCC) and were cultured, as described previously [ 25 ]. Primary PBMCs were obtained with informed consent (# 031019/2013).…”

“…All the cells were free of contamination, and the cell viability was determined by the TBE or AB assay, which were performed following the procedure that was described previously [ 25 , 26 ]. The cell morphology analysis was performed using cytospin and May-Grunwald-Giemsa staining as described previously [ 25 ]. To investigate caspase-3 activation, a caspase-3 colorimetric assay kit (Sigma-Aldrich Co.) was used.…”

Antitumor Effect of the Essential Oil from the Leaves of Croton matourensis Aubl. (Euphorbiaceae)

“…Cell viability was measured by the Alamar blue assay and was performed as previously described [ 34 , 35 , 36 ]. For all experiments, cells were plated in 96-well plates.…”