Hydroxyl radical (·OH) played a pivotal role in oridonin-induced apoptosis and autophagy in human epidermoid carcinoma A431 cells.

Abstract

Oridonin, a diterpenoid compound extracted and purified from Rabdosia rubescen, has been reported to induce tumor cell apoptosis through tyrosine kinase pathway. To further examine the mechanism of oridonin, we selected human epidermoid carcinoma A431 cell as a test object. Besides apoptosis, oridonin also induced A431 cell autophagy, and this autophagy antagonized apoptosis and played a protective role for A431 cells. Reactive oxygen species (ROS) played a pivotal role in induction of cytotoxicity. Therefore, a ROS scavenger, N-acetylcysteine (NAC) combined with oridonin was appiled. Results of morphologic observation, flow cytometric analysis and Western blot analysis showed that NAC could significantly reverse both ROS generation and down-regulation of mitochondrial membrane potential in oridonin treated cells. NAC inhibited oridonin induced apoptosis through both the intrinsic and extrinsic apoptotic pathways. NAC effectively inhibited both oridonin-induced apoptosis and autophagy by reducing intracellular oxidative stress. To further examine the mechanism of ROS, exogenous enzyme antioxidants (superoxide dismutase (SOD), catalase (CAT)) and non-enzyme antioxidants (glutathione (GSH)) were applied to detect the effect of oridonin on ROS generation. Only GSH exerted a similar role with NAC, suggesting that hydroxyl radical (·OH) played the major role in oridonin-induced cell death. Oridonin could decrease the GSH level in A431 cells in a dose-dependent manner. In addition, after treatment with ·OH donor, Fenton reagent, the changes in A431cells were similar to the results of oridonin treatment. All the results proved that ·OH played the pivotal role in oridonin induced apoptosis and autophagy in A431 cells.

• Authors: Yang Yu, Si Miao Fan, Jun Ke Song, Shin-ichi Tashiro, Satoshi Onodera, Takashi Ikejima
• Journal: Biological & pharmaceutical bulletin (Biol Pharm Bull) Vol. 35 Issue 12 Pg. 2148-59 ( 2012) ISSN: 1347-5215 [Electronic] Japan
• PMID: 23207767 (Publication Type: Journal Article)

Chemical References

• Antineoplastic Agents, Phytogenic
• Diterpenes, Kaurane
• Fenton's reagent
• Free Radical Scavengers
• Plant Extracts
• oridonin
• Hydroxyl Radical
• Hydrogen Peroxide
• Iron
• Protein-Tyrosine Kinases
• Glutathione
• Acetylcysteine

Topics

• Acetylcysteine (pharmacology)
• Antineoplastic Agents, Phytogenic (pharmacology, therapeutic use)
• Apoptosis (drug effects)
• Autophagy (drug effects)
• Carcinoma, Squamous Cell (drug therapy, metabolism, physiopathology)
• Cell Line, Tumor
• Diterpenes, Kaurane (pharmacology, therapeutic use)
• Dose-Response Relationship, Drug
• Down-Regulation
• Free Radical Scavengers (pharmacology)
• Glutathione (pharmacology)
• Humans
• Hydrogen Peroxide (pharmacology)
• Hydroxyl Radical (metabolism)
• Iron (pharmacology)
• Isodon (chemistry)
• Membrane Potential, Mitochondrial (drug effects, physiology)
• Oxidative Stress (drug effects)
• Phytotherapy
• Plant Extracts (pharmacology, therapeutic use)
• Protein-Tyrosine Kinases (metabolism)
• Signal Transduction