Shikonin time-dependently induced necrosis or apoptosis in gastric cancer cells via generation of reactive oxygen species.

The effects of shikonin on gastric cancer cells were investigated in this study. Exposure to shikonin reduced the viability of gastric cancer cells in a time- and dose-dependent manner. However, apoptosis was not observed in gastric cancer cell treatment with different concentrations of shikonin for 6h. By contrast, treatment with shikonin for 24h significantly induced apoptosis, as evidenced by the results of TUNEL assay and flow cytometry analysis in proportion to the concentration. Disruption of the mitochondrial membrane potential was observed in gastric cancer cells that were treated with shikonin for 6 and 24h. Pretreatment with necrostatin-1 recovered cell death and mitochondrial membrane potential in the 6h shikonin treatment, but not in the 24h shikonin treatment. Western blot results reveal enhanced p38 phosphorylation, downregulated AKT phosphorylation, and increased caspase3 and PARP cleavage in cells that were treated with shikonin for 24h, but not in cells treated for 6h. Shikonin also triggered reactive oxygen species (ROS) generation both in the 6 and 24h treatments. Pretreatment with N-acetylcysteine blocked shikonin-induced cell death. In summary, our findings suggest that shikonin, which may function as a promising agent in the treatment of gastric cancers, sequentially triggered necrosis or apoptosis through ROS generation in gastric cancer cells.

Ocimum gratissimum Aqueous Extract Induces Apoptotic Signalling in Lung Adenocarcinoma Cell A549.

Ocimum gratissimum (OG) is widely used as a traditional herb for its antibacterial activity in Taiwan. Recently, antitumor effect of OG on breast cancer cell is also reported; however, the effects of OG on human pulmonary adenocarcinoma cell A549 remain unclear. Therefore, we aimed to investigate whether aqueous OG extract (OGE) affects viability of A549 cells and the signals induced by OGE in A549 cells. Cell viability assays revealed that OGE significantly and dose-dependently decreased the viability of A549 cell but not that of BEAS-2B cell. Morphological examination and DAPI staining indicated that OGE induced cell shrinkage and DNA condensation for A549 cells. Further investigation showed that OGE enhanced activation of caspase-3, caspase-9 and caspase-8 and increased protein level of Apaf-1 and Bak, but diminished the level of Bcl-2. Additionally, OGE inhibited the phosphorylation of extracellular signal-regulated kinase (ERK) yet enhanced the phosphorylation of c-Jun N-terminal kinase (JNK) and p38 MAP kinase (p38). In conclusion, our findings indicate that OGE suppressed the cell viability of A549 cells, which may result from the activation of apoptotic signaling and the inhibition of anti-apoptotic signaling, suggesting that OGE might be beneficial to lung carcinoma treatment.

Ocimum gratissimum Aqueous Extract Protects H9c2 Myocardiac Cells from H(2)O(2)-Induced Cell Apoptosis through Akt Signalling.

Increased cell death of cardiomyocyte by oxidative stress is known to cause dysfunction of the heart. O. gratissimum is one of the more well-known medicinal plants among the Ocimum species and widely used in treatment of inflammatory diseases. In this study, we hypothesized that aqueous extract of O. gratissimum leaf (OGE) may protect myocardiac cell H9c2 from oxidative injury by hydrogen peroxide (H(2)O(2)). Our results revealed that OGE pretreatment dose-dependently protects H9c2 cells from cell death when exposed to H(2)O(2). Additionally, DNA condensation induced by H(2)O(2) was also reduced by OGE pretreatment, suggesting that Ocimum gratissimum extract may attenuate H(2)O(2)-induced chromosome damage. Further investigation showed that OGE pretreatment inhibited H(2)O(2)-induced activation of caspase-3 and caspase-9, as well as H(2)O(2)-induced upregulation of proapoptotic Apaf-1 and the release of cytosolic cytochrome c, but has little effect on the activation of caspase-8. Additionally, OGE pretreatment significantly upregulated Bcl-2 expression and Akt phosphorylation, and slightly affected the phosphorylation of mitogen-activated protein kinases including p38 MAPK and JNK. Taken together, our findings revealed that Ocimum gratissimum extract effectively inhibited the mitochondrial pathway and upregulated Bcl-2 expression, which may be important in protecting H9c2 cells from H(2)O(2)-induced cell death.