astaxanthine and Stomach-Neoplasms

Antioxidants are substances capable of inhibiting oxidation. In chronic diseases, inflammatory response cells produce oxygen free radicals. Oxygen free radicals cause DNA damage, and this may lead to gene modifications that might be carcinogenic. Chronic Helicobacter pylori infection causes the production of DNA-damaging free radicals. In recent years, various groups have studied the effects of antioxidants, especially on H. pylori-associated gastric cancer. In most of the studies, it has been shown that H. pylori infection does affect the level of antioxidants measured in the gastric juice, but there are also controversial results. Recent experimental studies, both in vivo and in vitro, have shown that vitamin C and astaxanthin, a carotenoid, are not only free radical scavengers but also show antimicrobial activity against H. pylori. It has been shown that astaxanthin changes the immune response to H. pylori by shifting the Th1 response towards a Th2 T-cell response. Very few experimental studies support the epidemiologic studies, and further studies are needed to describe the effect and the mechanism of antioxidants in the H. pylori immune response.

Topics: Antioxidants; Ascorbic Acid; beta Carotene; DNA Damage; Helicobacter Infections; Helicobacter pylori; Humans; Risk Factors; Stomach Neoplasms; Th1 Cells; Th2 Cells; Xanthophylls

Astaxanthin (ASX), a red‑colored xanthophyll carotenoid, functions as an antioxidant or pro‑oxidant. ASX displays anticancer effects by reducing or increasing oxidative stress. Reactive oxygen species (ROS) promote cancer cell death by necroptosis mediated by receptor‑interacting protein kinase 1 (RIP1) and RIP3. NADPH oxidase is a major source of ROS that may promote necroptosis in some cancer cells. The present study aimed to investigate whether ASX induces necroptosis by increasing NADPH oxidase activity and ROS levels in gastric cancer AGS cells. AGS cells were treated with ASX with or without ML171 (NADPH oxidase 1 specific inhibitor), N‑acetyl cysteine (NAC; antioxidant), z‑VAD (pan‑caspase inhibitor) or Necrostatin‑1 (Nec‑1; a specific inhibitor of RIP1). As a result, ASX increased NADPH oxidase activity, ROS levels and cell death, and these effects were suppressed by ML171 and NAC. Furthermore, ASX induced RIP1 and RIP3 activation, ultimately inducing mixed lineage kinase domain‑like protein (MLKL) activation, lactate dehydrogenase (LDH) release and cell death. Moreover, the ASX‑induced decrease in cell viability was reversed by Nec‑1 treatment and RIP1 siRNA transfection, but not by z‑VAD. ASX did not increase the ratio of apoptotic Bax/anti‑apoptotic Bcl‑2, the number of Annexin V‑positive cells, or caspase‑9 activation, which are apoptosis indices. In conclusion, ASX induced necroptotic cell death by increasing NADPH oxidase activity, ROS levels, LDH release and the number of propidium iodide‑positive cells, as well as activating necroptosis‑regulating proteins, RIP1/RIP3/MLKL, in gastric cancer AGS cells. The results of this study demonstrated the necroptotic effect of ASX on gastric cancer AGS cells, which required NADPH oxidase activation and RIP1/RIP3/MLKL signaling

Topics: Adenocarcinoma; Animals; Antitubercular Agents; Apoptosis; Cell Death; Cell Line, Tumor; Epithelial Cells; Humans; Imidazoles; Indoles; L-Lactate Dehydrogenase; NADPH Oxidases; Necroptosis; Protein Kinases; Rats; Reactive Oxygen Species; Receptor-Interacting Protein Serine-Threonine Kinases; Stomach Neoplasms; Xanthophylls

Astaxanthin is a carotenoid pigment that has antioxidant, antitumoral, and anti-inflammatory properties. In this in vitro study, we investigated the mechanism of anticancer effects of astaxanthin in gastric carcinoma cell lines.. The human gastric adenocarcinoma cell lines AGS, KATO-III, MKN-45, and SNU-1 were treated with various concentrations of astaxanthin. A cell viability test, cell cycle analysis, and immunoblotting were performed.. The viability of each cancer cell line was suppressed by astaxanthin in a dose-dependent manner with significantly decreased proliferation in KATO-III and SNU-1 cells. Astaxanthin increased the number of cells in the G0/G1 phase but reduced the proportion of S phase KATO-III and SNU-1 cells. Phosphorylated extracellular signal-regulated kinase (ERK) was decreased in an inverse dose-dependent correlation with astaxanthin concentration, and the expression of p27(kip-1) increased the KATO-III and SNU-1 cell lines in an astaxanthin dose-dependent manner.. Astaxanthin inhibits proliferation by interrupting cell cycle progression in KATO-III and SNU-1 gastric cancer cells. This may be caused by the inhibition of the phosphorylation of ERK and the enhanced expression of p27(kip-1).

Topics: Adenocarcinoma; Antineoplastic Agents; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Fibrinolytic Agents; Humans; Stomach Neoplasms; Xanthophylls