• Natural Product Sciences
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• v.3 no.1
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• pp.29-37
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• 1997

Protein Kinase C (PKC) is generally believed to play a central role in signal transduction, cellular growth control, gene expression, and tumor promotion. And it has been suggested that inhibitors of PKC might play important roles for the prevention and treatment of cancer. In order to investigate the possible inhibitors of PKC from natural products, PKC receptor binding assay was performed using bovine brain particulate as a source of PKC and the amount of $[^3H]Phorbol$ 12,13-dibutyrate (PDBu) bound to PKC was measured in the presence of test materials. Total methanol extracts from 100 kinds of natural products were partitioned into 3 fractions (n-hexane, ethyl acetate and aqueous layer) and their binding ability to the regulatory domain of PKC was evaluated. The ethyl acetate fractions of Morus alba $(roots,\;IC_{50}:\;156.6\;{\mu}g/ml)$, Rehmannia glutinosa $(roots,\;IC_{50}:\;134.3\;{\mu}g/ml)$, Lysimachia foenum-graecum $(roots,\;IC_{50}:\;167.8\;{\mu}g/ml)$, Polygonum cuspidata $(roots,\;IC_{50}:\;157.3\;{\mu}g/ml)$, Cnidium officinale $(aerial\;parts,\;IC_{50}:\;145.2\;{\mu}g/ml)$, and the hexane $(IC_{50}:\;179.3\;{\mu}g/ml)$ and the EtOAc fraction of Symplocarpus nipponicus $(roots,\;IC_{50}:\;155.9\;{\mu}g/ml)$ showed inhibitory activity of $[^3H]PDBu$ binding to PKC.

• Tuberculosis and Respiratory Diseases
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• v.71 no.2
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• pp.88-96
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• 2011

Background: It is known that cigarette smoke (CS) causes cell death. Apoptotic cell death is involved in the pathogenesis of CS-related lung diseases. Some members of the protein kinase C (PKC) family have roles in cigarette smoke extract (CSE)-induced apoptosis. This study was conducted to investigate the role of PKC epsilon in CSE-induced apoptosis in human lung fibroblast cell line, MRC-5. Methods: Lactate dehydrogenase release was measured using a cytotoxicity detection kit. The MTT assay was used to measure cell viability. Western immunoblot, Hoechst 33342 staining and flow cytometry were used to demonstrate the effect of $PKC{\varepsilon}$. Caspase-3 and caspase-8 activities were determined using a colorimetric assay. To examine $PKC{\varepsilon}$ activation, Western blotting was performed using both fractions of membrane and cytosol. Results: We showed that CSE activated $PKC{\varepsilon}$ by demonstrating increased expression of $PKC{\varepsilon}$ in the plasma membrane fraction. Pre-treatment of $PKC{\varepsilon}$ peptide inhibitor attenuated CSE-induced apoptotic cell death, as demonstrated by the MTT assay (13.03% of control, 85.66% of CSE-treatment, and 53.73% of $PKC{\varepsilon}$ peptide inhibitor-pre-treatment, respectively), Hoechst 33342 staining, and flow cytometry (85.64% of CSE-treatment, 53.73% of $PKC{\varepsilon}$ peptide inhibitor-pre-treatment). Pre-treatment of $PKC{\varepsilon}$ peptide inhibitor reduced caspase-3 expression and attenuated caspase-3, caspase-8 activity compared with CSE treatment alone. Conclusion: $PKC{\varepsilon}$ seem to have pro-apoptotic function and exerts its function through the extrinsic apoptotic pathway in CSE-exposed MRC-5 cells. This study suggests that $PKC{\varepsilon}$ inhibition may be a therapeutic strategy in CS-related lung disease such as chronic obstructive pulmonary disease.

• Journal of Microbiology and Biotechnology
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• v.5 no.2
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• pp.105-109
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• 1995

Anticancer activity of a fraction of the ethanol extract from the root of Korean angelica (Angelica gigas Nakai) was recognized in human cancer cell lines HeLa $S_3$, K-562, and Hep $G_2$. The extract blocked the phorbol ester-inducing megakaryocytic differentiation of K-562 cells, which indicated the modification of protein kinase C (PKC) activity. In vitro assay showed the activation of PKC by the extract. An effective fraction of the Angelica gigas extract, of which $R_f$ value was 0.64 in a thin layer chromatography, was a different component from those of European angelicas. The $ED_50$ value of the fraction was 8, 9, and $16\;\mu\textrm{m}/ml$ against HeLa $S_3\;Hep\;G_2$, and K-562 cells, respectively, while the fraction showed higher $ED_50$ values against normal cell lines.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.10
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• pp.5687-5692
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• 2013

Type 2 diabetes mellitus (T2DM) has contributed to advanced breast cancer development over the past decades. However, the mechanism underlying this contribution is poorly understood. In this study, we determined that high glucose enhanced proteasome activity was accompanied by enhanced proliferation, migration and invasion, as well as suppressed apoptosis, in human breast cancer MCF-7 cells. Proteasome inhibitor bortezomib (BZM) pretreatment mitigated high glucose-induced MCF-7 cell growth and invasion. Furthermore, high glucose increased protein kinase C delta ($PKC{\delta}$)-phosphorylation. Administration of the specific $PKC{\delta}$ inhibitor rottlerin attenuated high glucose-stimulated cancer cell growth and invasion. In addition, $PKC{\delta}$ inhibition by both rottlerin and $PKC{\delta}$ shRNA significantly suppressed high glucose-induced proteasome activity. Our results suggest that $PKC{\delta}$-dependent ubiquitin proteasome system activation plays an important role in high glucose-induced breast cancer cell growth and metastasis.

• Applied Microscopy
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• v.33 no.4
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• pp.299-313
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• 2003

The aim of the present study was to assess the role of protein kinase C (PKC) in the development of cardiac injury following scald burn. Sprague-Dawley rats were induced a scald burn a 15% total body surface area. Phorbol 12-myristate 13-acetate (PMA, 2 mg/kg) and bisindolylmaleimide (BIS, 0.05 mg/kg) were immediately administered i.p. after burn injury. 5 h and 24 h later, heart was removed and examined biochemical assay, ultrastructural changes and stereological analysis. The activity of serum aspartate aminotransferase was significantly increased at 5h (p<0.01) and 5h+BIS (p<0.001) after burn compared with that of control. The activity of serum creatinine was significantly decreased in PMA-treated groups after burn compared with postburn 5 h. PMA caused a decrease in MPO activity and induced wavy fibers in cardiac myocytes at postburn 5 and 24h. BIS induced contraction band, separation of intercalated disk and abnormal mitochondria in cardiac myocytes at postburn 5 and 24h. In stereological analysis, treatment of rats with PMA increased volume density of myofibril and mitochondria compared with postburn 5 and 24h. Our data suggest that the activation of PKC in scald burned heart decreases inflammation and protects the myocardium.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.8
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• pp.1328-1336
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• 2003

This study was done to investigate the effects of n-3, n-6 fatty acid and d-limonene on the hepatic membrane lipid composition, protein kinase C (PKC) and glutathione S-transferase (GST) activities in experimental rat hepatocarcinogenesis. Sprague-Dawley female rats were fed with two different types of dietary oil for 20 weeks. Corn oil (CO) and sardine oil (SO) were used at 15% by weight as a source of n-6 and n-3 fatty acid, respectively. One week after feeding, rats were intraperitoneally injected twice with a dose of diethylnitrosamine (DEN, 50 mg/kg body weight) and after 1 week 0.05% phenobarbital (PB) was provided with drinking water. Membrane fractional lipid composition showed that the content of cholesterol was higher in 50 group than CO group and also significantly decreased by d-limonene. The content of phospholipid was increased by carcinogen treatment but not affected by dietary oils or d-limonene. Membrane C/PL molar ratio was significantly decreased by d-limonene or carcinogen treatment in 50 groups but not in CO groups. Fatty acid composition was changed by dietary oils but not by carcinogen treatment or d-limonene. Cytosolic PKC activity was not significantly different by dietary oils, d-limonene or carcinogen treatment. However, membrane PKC activity was significantly increased by carcinogen treatment and decreased by d-limonene. Cytosolic GST activity was affected by d-limonene or carcinogen treatment in all dietary groups. These data indicate that dietary oils, d-limonene and carcinogen treatment can not change much membrane phospholipid composition. But membrane C/PL molar ratio was changed by carcinogen treatment and d -limonene although the effect was different between dietary oils. Therefore, it is suggested that different dietary oils and d-limonene can somewhat modulate the changes of membrane fluidity and activities of membrane bound enzymes like membrane associated PKC during carcinogenesis.

• Journal of Ginseng Research
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• v.22 no.2
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• pp.133-139
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• 1998

We have studied an activation mechanism of $pp60^{c-src}$ protein tyroslne kinase (PTK) by ginsenoside-$Rg_1$ (G-$Rg_1$ ) in NIH(pMcsrc/foc)B c-src overexpressor cells. It was previously reported that G--$Rg_1$ stimulated the activation of c-src kinase at 20 pM with a 18 hr-incubation, increasing the activity by 2-4-fold over that of untreated control, and this effect was blocked by treatments of in- hibitors of either protein synthesis (cycloheximide) or RNA synthesis (actinomycin D) (Hong, H.Y. et at. Arch. Pharm. Res. 16, 114 (1993)). However, an amount of c-src protein itself in wild-type cells was not changed by G-$Rg_1$. When the cells mutated at one or two tyrosine residue(s) (Y416/527) that are important sites to regulate the kinase activity were treated with G-$Rg_1$, increases both in the activity of c-src kinase and in the expression of the protein were not observed. In addition, removal of extracellular calcium ion by EGTA or inhibition of PKC by H-7 canceled the G-$Rg_1$-induced activation of the kinase. Although the activation was little affected by G-$Rg_1$ with a calcium ionophore A23187, it was synergistically stimulated by treatment of G-Rgl and PMA, a PKC activator. Taken together, these results suggest that the activation of c-src kinase by G-$Rg_1$ is caused by an increase in the specific activity of the kinase, but not in amount of it, and is involved with both collular calcium ion and PKC. Further the increase in the specific activity of c-src kinase may result from altered phosphorylation at tyro-416 and -527.

• Biomedical Science Letters
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• v.15 no.4
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• pp.287-293
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• 2009

Phospholipase D (PLD) is an enzyme hydrolyzing phosphatidylcholine to phosphatidic acid (PA) and choline. We investigated the involvement of PLD1 in the uptake of norepinephrine (NE) in PC12 cells, pheochromocytoma cells. NE uptake was specific in PC12 cells because nomifensine, a specific blocker of NE transporter, blocked NE uptake. Inhibition of PLD function in PC12 cells by the treatment of butanol suppressed the NE uptake. In contrast, overexpression of PLD1 in PC12 cells increased NE uptake efficiently. These results suggest that PLD activity is involved in NE uptake. We explored the action mechanism of PLD in NE uptake. PA phosphatase inhibitor, propranolol, blocks the formation of PKC activator diacylglycerol from PA. Propranolol treatment to PC12 cells blocked dramatically the uptake of NE. Specific PKC inhibitors, GF109203X and Ro31-8220, blocked NE uptake. Taken together, we suggest for the first time that PLD1 activity is involved in NE uptake via the activation of PKC.

• Journal of Photoscience
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• v.6 no.2
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• pp.71-75
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• 1999

Tempting to further understand the molecular mechanism of pharmacological action of ethanol, we evaluated effects of phosphatidylethanol (PET) on inositol 1,4,5-triphosphate (IP3) level and protein kinase C (PKC) activity in cultured NG108-15 cells. PET increased intracellular concentration of IP$_3$. PET incorporation into membranes of NG108-15 cells had no effect on the phosphorylation of the PKC-specific substrate MBP$\_$4-14/, thus indicates that PET does not affect PKC activity in this system.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.2
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• pp.315-320
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• 2008

This study investigated the signaling mechanisms contributed to the vasodilatory effects of HMC05, a herbal prescription. HMC05 acted in an endothelium-independent manner. To elucidate the fundamental mechanisms of its vascular actions, we focused on the signaling molecules involved in actin-myosin filament regulation including 20 kDa myosin light chains (LC20), Rho-associated kinase (ROCK), PKC, JNK and extracellular signal-regulated protein kinase (ERK) in the endothelium-denuded thoracic aorta or isolated smooth muscle cells (SMCs). It lowered the phosphorylation level of LC20 and showed that ROCK, ERK, JNK and $PKC{\alpha}$ pathways played important roles in the effects, as confirmed by the observations with a specific inhibition or activation, and with the activity and the subcellular localization of these molecules. In particular, HMC05 dramatically inhibited the activity of ERK and the downstream signaling of ROCK. It also changed the subcellular localization of the phophorylated $PKC{\alpha}$ as well as the amount of phosphorylation. Taken together, these data indicate that the vascular relaxation effects of HMC05 are attributed to the regulation of these signaling mechanisms.