Dihydroartemisinin accentuates the anti-tumor effects of photodynamic therapy via inactivation of NF-κB in Eca109 and Ec9706 esophageal cancer cells.

BACKGROUND: Photodynamic therapy (PDT) is a new treatment for esophageal cancer which has been shown to be effective in the elimination of tumor. However, PDT could induce the activation of nuclear factor-kappa B (NF-κB) in many photosensitizers based PDT, which plays a negative role in PDT. In addition, our previous results have shown that dihydroartemisinin (DHA), which was the most potent one of artemisinin derivatives, has anticancer activity in esophageal cancer cells. METHODS: Cell viability was determined by MTT analysis, and apoptosis was evaluated by flow cytometry. Nuclear extract was obtained for determining NF-κB DNA-binding activity, while total protein extract obtained for downstream gene expression by western blot. RESULTS: We demonstrated DHA enhanced PDT-induced growth inhibition and apoptosis in both human esophageal cancer cell lines Eca109 and Ec9706 in vitro. The mechanism was at least partially due to DHA deactivated PDT-induced NF-κB activation, so as to decrease tremendously the expression of its target gene Bcl-2. CONCLUSION: Our results demonstrate that DHA augments PDT-induced growth inhibition and apoptosis in esophageal cancer cells, and that inactivation of NF-κB activity is a potential mechanism by which DHA sensitizes esophageal cancer cells to PDT-induced growth inhibition and apoptosis.

Sonodynamically induced anti-tumor effect of 5-aminolevulinic acid on pancreatic cancer cells.

Sonodynamic therapy (SDT), a promising modality for cancer treatment, involves the synergistic interaction of ultrasound and some chemical compounds termed sonosensitizers. However, its effect on pancreatic cancer cells remains unclear. In our study, we sought to identify the cytotoxic effects of ultrasound-activated 5-aminolevulinic acid on human pancreatic cancer Capan-1 cells. Cell viability was determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide) analysis; mitochondrial membrane potential was assessed using the fluorescent probe jc-1; apoptosis was evaluated by flow cytometry; cell morphology was investigated by scanning electron microscopy; apoptosis-related protein expression was analyzed by Western blot assay. We found that SDT significantly decreased the survival rate of cells, and this effect increased with 5-aminolevulinic acid concentration and ultrasound exposure time. The mechanism underlying the effect of SDT involves, in part, the induction of a conspicuous loss in mitochondrial membrane potential and, in part, the induction of apoptosis through upregulation of Bax expression, downregulation of Bcl-2 and increased activation of procaspase-3. These results indicate that the ultrasonically induced cell killing effect could be enhanced by 5-ALA and that the mitochondrial pathway might be involved in the cell damage process. We conclude that SDT is a promising new methodology for pancreatic cancer treatment.

Initiation of apoptosis, cell cycle arrest and autophagy of esophageal cancer cells by dihydroartemisinin.

Dihydroartemisinin (DHA) has recently been shown anti-tumor activity in various cancer cells. However, its effect on esophageal cancer remains unclear. In this study, for the first time, we demonstrated that DHA reduced viability of esophageal cancer cells in a dose-dependent manner. The mechanism was at least partially due to DHA induced apoptosis by upregulating the expression of Bax, downregulating Bcl-2, Bcl-xL and Procaspase-3, and increasing caspase-9 activation, induced cell cycle arrest by downregulating cyclin E, CDK2 and CDK4. Furthermore, we firstly found that DHA induced autophagy in cancer cells. We concluded DHA might be a novel agent against esophageal cancer.