Hwa Jin Moon

Gallic acid inhibits the growth of HeLa cervical cancer cells via apoptosis and/or necrosis

Gallic acid (GA) is widely distributed in various plants and foods, and its various biological effects have been reported. Here, we evaluated the effects of GA on HeLa cells in relation to cell growth inhibition and death. HeLa cell growth was diminished with an IC(50) of approximately 80 microM GA at 24h whereas an IC(50) of GA in human umbilical vein endothelial cells (HUVEC) was approximately 400 microM. GA-induced apoptosis and/or necrosis in HeLa cells and HUVEC, which was accompanied by the loss of mitochondrial membrane potential (MMP; DeltaPsi(m)). The percentages of MMP (DeltaPsi(m)) loss cells and death cells were lower in HUVEC than HeLa cells. All the tested caspase inhibitors (pan-caspase, caspase-3, -8 or -9 inhibitor) significantly rescued HeLa cells from GA-induced cell death. GA increased reactive oxygen species (ROS) level and GSH (glutathione) depleted cell number in HeLa cells. Caspase inhibitors reduced GSH depleted cell number but not ROS level in GA-treated HeLa cells. In conclusion, GA inhibited the growth of HeLa cells and HUVEC via apoptosis and/or necrosis. The susceptibility of HeLa cells to GA was higher than that of HUVEC. GA-induced HeLa cell death was accompanied by ROS increase and GSH depletion.

Effects of carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone on the growth inhibition in human pulmonary adenocarcinoma Calu-6 cells.

Carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP) is an uncoupler of mitochondrial oxidative phosphorylation in eukaryotic cells. Here, we evaluated the in vitro effects of FCCP on the growth of Calu-6 lung cancer cells. FCCP inhibited the growth of Calu-6 cells with an IC(50) of approximately 6.64+/-1.84 microM at 72 h, as shown by MTT. DNA flow cytometric analysis indicated that FCCP induced G1 phase arrest below 20 microM of FCCP. Treatment with FCCP decreased the level of CDKs and cyclines in relation to G1 phase. In addition, FCCP not only increased the p27 level but also enhanced its binding with CDK4, which was associated with hypophosphorylation of Rb protein. While transfection of p27 siRNA inhibited G1 phase arrest in FCCP-treated cells, it did not enhance Rb phosphorylation. FCCP also efficiently induced apoptosis. The apoptotic process was accompanied with an increase in sub-G1 cells, annexin V staining cells, mitochondria membrane potential (MMP) loss and cleavage of PARP protein. All of the caspase inhibitors (caspase-3, -8, -9 and pan-caspase inhibitor) markedly rescued the Calu-6 cells from FCCP-induced cell death. However, knock down of p27 protein intensified FCCP-induced cell death. Moreover, FCCP induced the depletion of GSH content in Calu-6 cells, which was prevented by all of the caspase inhibitors. In summary, our results demonstrated that FCCP inhibits the growth of Calu-6 cells in vitro. The growth inhibitory effect of FCCP might be mediated by cell cycle arrest and apoptosis via decrease of CDKs and caspase activation, respectively. These findings now provide a better elucidation of the mechanisms involved in FCCP-induced growth inhibition in lung cancer.

Propyl gallate inhibits the growth of calf pulmonary arterial endothelial cells via glutathione depletion.

Propyl gallate (PG) as a synthetic antioxidant exerts a variety of effects on tissue and cell functions. Here, we evaluated the effects of PG on the growth and death of endothelial cells (ECs), especially calf pulmonary artery endothelial cells (CPAEC) in relation to reactive oxygen species (ROS) and glutathione (GSH). PG dose-dependently inhibited the growth of CPAEC and human umbilical vein endothelial cells (HUVEC) at 24h. PG induced cell death in CPAEC, which was accompanied by the loss of mitochondrial membrane potential (MMP; DeltaPsi(m)). PG generally increased ROS level in CPAEC but not in HUVEC. PG also dose-dependently increased GSH depleted cells in both ECs. The treatment with antioxidant of N-acetyl-cysteine (NAC) or ascorbate acid (AA) prevented CPAEC growth inhibition and death by PG, which was accompanied by the attenuation of GSH depletion but not by the reduction of ROS level. In conclusion, PG induced growth inhibition and death of ECs, especially CPAEC via GSH depletion.

The effects of MAPK inhibitors on pyrogallol-treated Calu-6 lung cancer cells in relation to cell growth, reactive oxygen species and glutathione.

Pyrogallol (PG) as a polyphenol compound can generate superoxide anion (O(2)(-)). Here, we investigated the effects of PG and/or MAPK inhibitors on Calu-6 lung cells in relation to cell growth, cell death, reactive oxygen species (ROS) and GSH levels. PG inhibited the growth of Calu-6 cells and induced apoptosis, which was accompanied by the loss of mitochondrial membrane potential (MMP; DeltaPsi(m)). While general ROS were decreased in PG-treated Calu-6 cells at 72h, intracellular O(2)(-) level including mitochondrial O(2)(-) was increased. PG also increased GSH depleted cell number in Calu-6 cells. MEK inhibitor slightly prevented cell growth inhibition, cell death and GSH depletion by PG. JNK inhibitor did not affect cell growth, cell death, MMP (DeltaPsi(m)) loss, ROS level and GSH deletion in PG-treated Calu-6 cells but p38 inhibitor mildly enhanced MMP (DeltaPsi(m)) loss, O(2)(-) level and GSH depletion in these cells. Conclusively, MEK inhibitor slightly prevented growth inhibition and death in PG-treated Calu-6 cells. Growth inhibition and death in Calu-6 cells by PG and/or MAPK inhibitors were partially related to O(2)(-) level and GSH content changes.

The Attenuation of MG132, a Proteasome Inhibitor, Induced A549 Lung Cancer Cell Death by p38 Inhibitor in ROS-Independent Manner

MG132, as a proteasome inhibitor, can induce apoptotic cell death through formation of reactive oxygen species (ROS). In this study, we investigated the effects of MAPK (MEK, JNK, and p38) inhibitors on MG132-treated A549 lung cancer cells in relation to cell growth, cell death, ROS, and glutathione (GSH) levels. Treatment with 10 microM MG132 inhibited the growth of A549 cells at 24 h. MG132 also induced apoptosis, which was accompanied by the loss of mitochondrial membrane potential (MMP; deltapsi(m)). ROS were not increased in MG132-treated A549 cells. MG132 increased GSH-depleted cell numbers and decreased GSH levels. MEK and JNK inhibitors did not strongly affect cell growth, cell death, ROS, and GSH levels in MG132-treated A549 cells. In contrast, p38 inhibitor reduced cell growth inhibition, apoptosis, and MMP (deltapsi(m)) loss by MG132. However, p38 inhibitor did not change ROS level and GSH content. In conclusion, MG132 inhibited the growth of A549 cells via apoptosis without formation of ROS. Treatment with p38 inhibitor rescued some cells from MG132-induced apotposis, which was not affected by ROS and GSH level changes.

The MEK inhibitor PD98059 attenuates growth inhibition and death in gallic acid-treated Calu-6 lung cancer cells by preventing glutathione depletion

Gallic acid (GA) is widely distributed in various plants and foods and has various biological effects. In this study, we investigated the effects of mitogen-activated protein kinase (MEK, JNK or p38) inhibitors on GA-induced Calu-6 lung cancer cell death in relation to reactive oxygen species (ROS) and glutathione (GSH) levels. GA inhibited the growth of Calu-6 cells and induced apoptosis and/or necrosis accompanied by the loss of mitochondrial membrane potential (MMP; Δψm). ROS levels and the number of GSH-depleted cells were observed to be increased at 24 h. MEK inhibitor suppressed cell growth inhibition, death, MMP (Δψm) loss and GSH depletion induced by GA, but failed to suppress the increase in ROS levels. JNK inhibitor also somewhat suppressed cell growth inhibition, MMP (Δψm) loss and GSH depletion induced by GA, and limited the increase in ROS levels. By contrast, p38 inhibitor mildly enhanced GA-induced cell growth inhibition, MMP (Δψm) loss and the increase in ROS levels. In conclusion, MEK inhibitor suppressed GA-induced cell growth inhibition and death in Calu-6 cells. This was related to the prevention of GSH depletion.