Oral cancer is a cause of cancer-associated mortality worldwide and the treatment of oral cancer includes radiation, surgery and chemotherapy. Quercetin is a component from natural plant products and it has been demonstrated that quercetin is able to induce cytotoxic effects through induction of cell apoptosis in a number of human cancer cell lines. However, there is no available information to demonstrate that quercetin is able to induce apoptosis in human oral cancer cells. In the present study, the effect of quercetin on the cell death via the induction of apoptosis in human oral cancer SAS cells was investigated using flow cytometry, Annexin V/propidium iodide (PI) double staining, western blotting and confocal laser microscopy examination, to test for cytotoxic effects at 6–48 h after treatment with quercetin. The rate of cell death increased with the duration of quercetin treatment based on the results of a cell viability assay, increased Annexin V/PI staining, increased reactive oxygen species and Ca2+ production, decreased the levels of mitochondrial membrane potential (ΔΨm), increased proportion of apoptotic cells and altered levels of apoptosis-associated protein expression in SAS cells. The results from western blotting revealed that quercetin increased Fas, Fas-Ligand, fas-associated protein with death domain and caspase-8, all of which associated with cell surface death receptor. Furthermore, quercetin increased the levels of activating transcription factor (ATF)-6α, ATF-6β and gastrin-releasing peptide-78 which indicated an increase in endoplasm reticulum stress, increased levels of the pro-apoptotic protein BH3 interacting-domain death antagonist, and decreased levels of anti-apoptotic proteins B-cell lymphoma (Bcl) 2 and Bcl-extra large which may have led to the decreases of ΔΨm. Additionally, confocal microscopy suggested that quercetin was able to increase the expression levels of cytochrome c, apoptosis-inducing factor and endonuclease G, which are associated with apoptotic pathways. Therefore, it is hypothesized that quercetin may potentially be used as a novel anti-cancer agent for the treatment of oral cancer in future.

The aim of the present study was to investigate the cytotoxic effects of bufalin on SCC-4 human tongue cancer cells. Cell morphological changes and viability were examined using phase contrast microscopy and flow cytometry, respectively. The results indicated that bufalin induced morphological changes and reduced total viable cells. Apoptotic cell death was analyzed by DAPI staining and DNA gel electrophoresis; the results revealed that bufalin induced cell apoptosis. Levels of reactive oxygen species (ROS), Ca2+, nitric oxide (NO) and mitochondrial membrane potential (ΔΨm) were measured by flow cytometry, and bufalin was observed to increase Ca2+ and NO production, decrease the ΔΨm and reduce ROS production in SCC-4 cells. In addition, western blotting was performed to detect apoptosis-associated protein expression. The results demonstrated that bufalin reduced the expression of the anti-apoptotic protein B-cell lymphoma 2 (Bcl-2) and increased the expression of the pro-apoptotic protein, Bcl-2-associated X protein. However, bufalin treatment also increased the expression of other apoptosis-associated proteins such as apoptosis-inducing factor and endonuclease G in SCC-4 cells. Based on these findings, bufalin may induce apoptotic cell death via mitochondria-dependent pathways in human tongue cancer SCC-4 cells.

Background/Aim: Lung cancer notably contributes to tumor-associated mortality worldwide, and standard chemotherapy is used for lung cancer patients. However, its therapeutic efficacy remains unsatisfactory. This study aimed to evaluate the effects and molecular mechanisms of sorafenib and bufalin combination therapy on lung cancer cells in vitro. Materials and Methods: NCI-H292 cells were treated with sorafenib, bufalin, and sorafenib in combination with bufalin. Cell viability, ROS production, Ca 2+ release, and mitochondrial membrane potential were examined by flow cytometric assay. Annexin V/PI staining and chromatin condensation were examined by the apoptosis assays. Finally the molecular mechanism of apoptosis-associated protein expression was investigated by western blotting. Results: NCI-H292 cells treated with sorafenib in combination with bufalin showed significantly decreased viability, enhanced cellular apoptosis, and DNA condensation when compared to that with sorafenib or bufalin alone. Moreover, the combination treatment exhibited higher reactive oxygen species (ROS) production and lower mitochondrial membrane potential (ΔΨm). The combined treatment resulted in higher expression of SOD but lower catalase compared to sorafenib treatment alone. Compared to sorafenib or bufalin treatment alone, the combination treatment resulted in lower Bcl-2 expression but higher Bax, Bad, APAF-1, caspase-3, and caspase-9. Conclusion: Sorafenib in combination with bufalin shows more potent cytotoxic effects and cell apoptosis than sorafenib or bufalin treatment alone in NCI-H292 cells. The combined treatment significantly enhanced apoptotic cell death in NCI-H292 lung cancer cells by activating ROS-, mitochondria-, and caspase-signaling pathways in vitro.Cancer affects human health globally with its incidence being the most severe public issue of the 21 st century. The global number of lung cancer deaths remains high yearly (1). Lung cancers are mainly divided into two subtypes, including nonsmall cell lung cancer (NSCLC) and small cell lung cancer (SCLC). However, the NSCLC subtype occupies about 80-85% of lung cancers (2). Currently, patients undergo surgery, radiation, chemotherapy, and targeted therapy as the most commonly used strategies for lung cancer. Yet clinical outcomes of current therapies remain unsatisfactory: the 5year survival rate of lung cancer patients is less than 15% (3), and that of patients with metastatic disease is less than 10% 582 This article is freely accessible online.

Fisetin, a naturally occurring flavonoid, is found in common fruits and vegetables and has been shown to induce cytotoxic effects in many human cancer cell lines. No information has shown that fisetin induced cell cycle arrest and apoptosis in mouse leukemia WEHI-3 cells. We found that fisetin decreased total viable cells through G0/G1 phase arrest and induced sub-G1 phase (apoptosis). We have confirmed fisetin induced cell apoptosis by the formation of DNA fragmentation and induction of apoptotic cell death. Results indicated that fisetin induced intracellular Ca[Formula: see text] increase but decreased the ROS production and the levels of [Formula: see text]m in WEHI-3 cells. Fisetin increased the activities of caspase-3, -8 and -9. Cells were pre-treated with inhibitors of caspase-3, -8 and -9 and then treated with fisetin and results showed increased viable cell number when compared to fisetin treated only. Fisetin reduced expressions of cdc25a but increased p-p53, Chk1, p21 and p27 that may lead to G0/G1 phase arrest. Fisetin inhibited anti-apoptotic protein Bcl-2 and Bcl-xL and increased pro-apoptotic protein Bax and Bak. Furthermore, fisetin increased the protein expression of cytochrome c and AIF. Fisetin decreased cell number through G0/G1 phase arrest via the inhibition of cdc25c and induction of apoptosis through caspase-dependent and mitochondria-dependent pathways. Therefore, fisetin may be useful as a potential therapeutic agent for leukemia.