Molecular and Functional Characterization of Choline Transporter-Like Proteins in Esophageal Cancer Cells and Potential Therapeutic Targets

In this study, we examined the molecular and functional characterization of choline uptake in the human esophageal cancer cells. In addition, we examined the influence of various drugs on the transport of [3H]choline, and explored the possible correlation between the inhibition of choline uptake and apoptotic cell death. We found that both choline transporter-like protein 1 (CTL1) and CTL2 mRNAs and proteins were highly expressed in esophageal cancer cell lines (KYSE series). CTL1 and CTL2 were located in the plasma membrane and mitochondria, respectively. Choline uptake was saturable and mediated by a single transport system, which is both Na+-independent and pH-dependent. Choline uptake and cell viability were inhibited by various cationic drugs. Furthermore, a correlation analysis of the potencies of 47 drugs for the inhibition of choline uptake and cell viability showed a strong correlation. Choline uptake inhibitors and choline deficiency each inhibited cell viability and increased caspase-3/7 activity. We conclude that extracellular choline is mainly transported via a CTL1. The functional inhibition of CTL1 by cationic drugs could promote apoptotic cell death. Furthermore, CTL2 may be involved in choline uptake in mitochondria, which is the rate-limiting step in S-adenosylmethionine (SAM) synthesis and DNA methylation. Identification of this CTL1- and CTL2-mediated choline transport system provides a potential new target for esophageal cancer therapy.

Novel non-apoptotic cell death: ferroptosis / 영남의대학술지

Ferroptosis is a newly recognized type of cell death that results from iron-dependent lipid peroxidation and is different from other types of cell death, such as apoptosis, necrosis, and autophagic cell death. This type of cell death is characterized by mitochondrial shrinkage with an increased mitochondrial membrane density and outer mitochondrial membrane rupture. Ferroptosis can be induced by a loss of activity of system Xc− and the inhibition of glutathione peroxidase 4, followed by the accumulation of lipid reactive oxygen species (ROS). In addition, inactivation of the mevalonate and transsulfuration pathways is involved in the induction of ferroptosis. Moreover, nicotinamide adenine dinucleotide phosphate oxidase and p53 promote ferroptosis by increasing ROS production, while heat shock protein beta-1 and nuclear factor erythroid 2-related factor 2 inhibit ferroptosis by reducing iron uptake. This article outlines the molecular mechanisms and signaling pathways of ferroptosis regulation, and explains the roles of ferroptosis in human disease.

Novel non-apoptotic cell death: ferroptosis / 영남의대학술지

Ferroptosis is a newly recognized type of cell death that results from iron-dependent lipid peroxidation and is different from other types of cell death, such as apoptosis, necrosis, and autophagic cell death. This type of cell death is characterized by mitochondrial shrinkage with an increased mitochondrial membrane density and outer mitochondrial membrane rupture. Ferroptosis can be induced by a loss of activity of system Xc− and the inhibition of glutathione peroxidase 4, followed by the accumulation of lipid reactive oxygen species (ROS). In addition, inactivation of the mevalonate and transsulfuration pathways is involved in the induction of ferroptosis. Moreover, nicotinamide adenine dinucleotide phosphate oxidase and p53 promote ferroptosis by increasing ROS production, while heat shock protein beta-1 and nuclear factor erythroid 2-related factor 2 inhibit ferroptosis by reducing iron uptake. This article outlines the molecular mechanisms and signaling pathways of ferroptosis regulation, and explains the roles of ferroptosis in human disease.

Effects of LED irradiation on the expression of apoptosis-related molecules in human SH-SY5Y neuroblastoma cells

To verify the inhibitory or protective effects of light-emitting diode(LED) irradiation on apoptotic cell death induced by CoCl2, human SH-SY5Y cells were treated with CoCl2 and LED were used to irradiate the cells. In the cell viability assay, cells were died slowly from 50 micrometer to 250 micrometer and about 50% of cells died after 12 hours at 400 micrometer of CoCl2. The Diff-Quik staining revealed that cells showed condensation of DNA and blebbing of the cell membrane. The DNA fragmentation assay revealed the DNA fragmentation, which is another apoptosis marker, occurred in cells treated with 400 micrometer CoCl2 for 16 hours. In the western blot for HIF-1 alpha, HIF-1 alpha was expressed after 3 hours from induction and peaked maximally at 16 hours. In the cell viability assay of the effects of LED irradiation (at 590 nm for 1 hour 20 minutes), the cells showed more proliferation (about 20%) than the control group. The RPA assay of various apoptosis-related molecules showed that pro-apoptosis molecules such as Bax, Bak, and Bid were upregulated in the CoCl2 treatment group. This means that the apoptotic cell population was increased. However there was some significant changes in LED irradiated cells. In the CoCl2-treated LED irradiation group, those molecules were down-regulated more than in the only CoCl2-treated group. These results have shown that CoCl2 may induce apoptotic cell death in human SH-SY5Y neuroblastoma cells. And LED irradiation has a positive effect on apoptotic cells by down-regulation of pro-apoptotic molecules.

The Effect of Nitric Oxide on Cultured Bovine Retinal Pigment Epithelial Cell

Nitric oxide (NO), a potencially toxic radical, is generally regarded as a multi-potent molecule to be implicated in a wide range of biological function. The presence of nitric oxide synthase(NOS) in the retina, the constitutive isoform in photoreceptor outer segments and and the inducible form in retinal pigment epithelial (RPE) cells, has been demonstrated. The effect of NO in retina has been studying mainly as neurotransmitter. Present study was undertaken to find the role of NO in cultured bovine retinal pigment epithelial cells. Cultured bovine retinal pigment epithelial cells were treated with various concentrations of NO generator, S-nitroso-N-acetyl-D, L-penicillamine (SNAP). The survival fractions were measured by MTT assay. The morphologic changes were observed with inverted phase contrast microscope and electron microscope. To evaluate the characteristics of cell death, cells were lysed for DNA extraction, and the agarose gel electrophoresis was done. NO brought a decrease in the survival fraction of cultured bovine retinal pigment epithelial cells as concentrations increased. At high concentrations, cells became sparse. Electron microscopic study showed destruction of nuclear membrane and chromatin condensation in 1 mM SNAP treated group. These findings were compatible with apoptotic cell death that was supported with DNA laddering pattern in agarose gel electrophoresis. NO can induce damage to retinal pigment epithelial cells, and damaged cells are destined to apoptotic cell death.