• Journal of Life Science
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• v.23 no.5
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• pp.689-697
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• 2013

In the United States, about 40,000 new cases of oral cancer are diagnosed each year and nearly 7,800 patients died from it in 2012. Omega-3 polyunsaturated fatty acids have been found to have anticancer effects in a variety of cancer cell lines and animal models, but their effect in oral cancer remains unclear. This study was designed to examine the effect of docosahexaenoic acid (DHA, a kind of omega-3 fatty acid) on oral cancer cells and the molecular mechanism of its action. We found that exposure of squamous cell carcinoma-4 (SCC-4) and squamous cell carcinoma-9 (SCC-9) human oral cancer cells to DHA induced growth inhibition in a dose- and time-dependent manner. Meanwhile, in addition to the elevated levels of apoptotic markers, such as cleaved PARP, subG1 portion and TUNEL-positive nuclei, DHA led to autophagic vesicle formation and an increase in autophagic flux, indicating the involvement of both apoptosis and autophagy in the inhibitory effects of DHA on oral cancer cells. Further experiments revealed that the apoptosis and autophagy induced by DHA were linked to inhibition of mammalian target of rapamycin (mTOR) signaling by AKT inhibition and AMP-activated protein kinase (AMPK) activation in SCC-9 cells. Together, our results suggest that DHA induces apoptosis- and autophagy-associated cell death through the AMPK/AKT/mTOR signaling pathway in oral cancer cells. Thus, utilization of omega-3 fatty acids may represent a promising therapeutic approach for chemoprevention and treatment of human oral cancer.

• Journal of Life Science
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• v.33 no.9
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• pp.713-723
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• 2023

Lung cancer is a type of cancer that has the highest mortality rate. It is mainly classified into small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC). Chemotherapy is used to treat lung cancer, but long-term treatment causes side effects and drug resistances. Curcumin is a bright yellow polyphenol extracted from the root of turmeric. It has biological activities, such as anti-oxidant, anti-cancer, and anti-inflammatory effects. In this study, we observed differential cell death in human lung cancer cells. Based on the results, curcumin at 10, 30, and 50 μM exhibited a dose-dependent inhibition on the cell survival of several lung cancer cells, with minor differential phenotypes. In addition, apoptosis, autophagy, and reactive oxygen species (ROS) regeneration were observed through flow cytometry. Curcumin dose-dependently increased these phenotypes in A549 (NSCLC) and DMS53 (SCLC), which were restored by corresponding inhibitors. Western blotting was performed to measure the level of expression of apoptosis- and autophagy-related proteins. The results indicate that Bax, PARP, pro-caspase-3, and Bcl-2 were dose-dependently regulated by curcumin, with seemingly higher Bax/Bcl-2 ratios in DMS53. In addition, autophagic proteins, p-AKT, p62, and LC3B, were dose-dependently regulated by curcumin. ROS inhibition by diphenyleneiodonium reduced the induction of apoptosis and autophagy generated by curcumin. Taken together, it is suggested that curcumin induces apoptosis and autophagy via ROS generation, leading to cell death, with minor differences between human lung cancer cells.

• Molecules and Cells
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• v.43 no.1
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• pp.66-75
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• 2020

Saturated fatty acids contribute to β-cell dysfunction in the onset of type 2 diabetes mellitus. Cellular responses to lipotoxicity include oxidative stress, endoplasmic reticulum (ER) stress, and blockage of autophagy. Palmitate induces ER Ca²⁺ depletion followed by notable store-operated Ca²⁺ entry. Subsequent elevation of cytosolic Ca²⁺ can activate undesirable signaling pathways culminating in cell death. Mitochondrial Ca²⁺ uniporter (MCU) is the major route for Ca²⁺ uptake into the matrix and couples metabolism with insulin secretion. However, it has been unclear whether mitochondrial Ca²⁺ uptake plays a protective role or contributes to lipotoxicity. Here, we observed palmitate upregulated MCU protein expression in a mouse clonal β-cell, MIN6, under normal glucose, but not high glucose medium. Palmitate elevated baseline cytosolic Ca²⁺ concentration ([Ca²⁺]_i) and reduced depolarization-triggered Ca²⁺ influx likely due to the inactivation of voltage-gated Ca²⁺ channels (VGCCs). Targeted reduction of MCU expression using RNA interference abolished mitochondrial superoxide production but exacerbated palmitate-induced [Ca²⁺]_i overload. Consequently, MCU knockdown aggravated blockage of autophagic degradation. In contrast, co-treatment with verapamil, a VGCC inhibitor, prevented palmitate-induced basal [Ca²⁺]_i elevation and defective [Ca²⁺]_i transients. Extracellular Ca²⁺ chelation as well as VGCC inhibitors effectively rescued autophagy defects and cytotoxicity. These observations suggest enhanced mitochondrial Ca²⁺ uptake via MCU upregulation is a mechanism by which pancreatic β-cells are able to alleviate cytosolic Ca²⁺ overload and its detrimental consequences.

• Herbal Formula Science
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• v.29 no.2
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• pp.71-80
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• 2021

Objectives : This study investigated cellular-protective effects of Nardotidis seu Sulculii Concha water extract (NSCE) against oxidative stress induced by arachidonic acid (AA)+iron or tert-butylhydroperoxide (tBHP). Methods : In vitro, MTT assay was assessed for cell viability, and immunoblotting analysis was performed to detect expression of AMP-activated kinase (AMPK) signaling pathway and autophagy related proteins. In vivo, mice were orally administrated with the aqueous extract of NSCE of 500 mg/kg for 3 days, and then injected with CCl₄ 0.5 mg/kg body weight to induce acute damage. The level of liver damage was measured by serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) analysis. Results : Treatment with NSCE inhibited cell death induced by AA+iron and tBHP. NSCE induced the phosphorylation of AMPK, and this compound also induced the phosphorylation of LKB1, an upstream kinase of AMPK, and Acetyl-CoA carboxylase (ACC), a primary downstream target of AMPK. NSCE increased the protein levels of autophagic markers (LC3II and beclin-1) and decreased the phosphorylation of mammalian target of rapamycin (mTOR) and simultaneously increased the phosphorylation of unc-51-like kinase-1 (ULK-1) in time-dependent manner. Conclusions : NSCE has the ability 1) to protect cells against oxidative stress induced by AA+iron or tBHP. NSCE 2) to activate AMP-activated protein kinase (AMPK), and 3) to regulate autophagy, an important regulator in cell survival.

• Journal of Microbiology and Biotechnology
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• v.27 no.1
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• pp.197-205
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• 2017

Exposure of Jurkat T cell clone (J/Neo cells) to acacetin (5,7-dihydroxy-4'-methoxyflavone), which is present in barnyard millet (Echinochloa esculenta (A. Braun)) grains, caused cytotoxicity, enhancement of apoptotic $sub-G_1$ rate, Bak activation, loss of mitochondrial membrane potential (${\Delta}{\Psi}m$), activation of caspase-9 and caspase-3, degradation of poly(ADP-ribose) polymerase, and FITC-Annexin V-stainable phosphatidylserine exposure on the external surface of the cytoplasmic membrane without accompanying necrosis. These apoptotic responses were abrogated in Jurkat T cell clone (J/Bcl-xL) overexpressing Bcl-xL. Under the same conditions, cellular autophagic responses, including suppression of the Akt-mTOR pathway and p62/SQSTM1 down-regulation, were commonly detected in J/Neo and J/Bcl-xL cells; however, formation of acridine orange-stainable acidic vascular organelles, LC3-I/II conversion, and Beclin-1 phosphorylation (Ser-15) were detected only in J/Neo cells. Correspondingly, concomitant treatment with the autophagy inhibitor (3-methyladenine or LY294002) appeared to enhance acacetin-induced apoptotic responses, such as Bak activation, ${\Delta}{\Psi}m$ loss, activation of caspase-9 and caspase-3, and apoptotic $sub-G_1$ accumulation. This indicated that acacetin could induce apoptosis and cytoprotective autophagy in Jurkat T cells simultaneously. Together, these results demonstrate that acacetin induces not only apoptotic cell death via activation of Bak, loss of ${\Delta}{\Psi}m$, and activation of the mitochondrial caspase cascade, but also cytoprotective autophagy resulting from suppression of the Akt-mTOR pathway. Furthermore, pharmacologic inhibition of the autophagy pathway augments the activation of Bak and resultant mitochondrial damage-mediated apoptosis in Jurkat T cells.

• Tuberculosis and Respiratory Diseases
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• v.69 no.1
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• pp.16-23
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• 2010

Background: Most lung cancer patients receive systemic chemotherapy at an advanced stage disease. Cisplatin-based chemotherapy is the main regimen for treating advanced lung cancer. Recently, autophagy has become an important mechanism of cellular adaptation under starvation or cell oxidative stress. The purpose of this study was to determine whether or not autophagy can occurred in cisplatin-treated lung cancer cells. Methods: H460 cells were incubated with RPMI 1640 and treated in $5{\mu}M$ or $20{\mu}M$ cisplatin concentrations at specific time intervals. Cells surviving cisplatin treatment were measured and compared using an MTT cell viability assay to cells that underwent apoptosis with autophagy by nuclear staining, apoptotic or autophagic related proteins, and autophagic vacuoles. The development of acidic vascular organelles was using acridine orange staining and fluorescent expression of GFP-LC3 protein in its transfected cells was observed to evaluate autophagy. Results: Lung cancer cells treated with $5{\mu}M$ cisplatin-treated were less sensitive to cell death than $20{\mu}M$ cisplatin-treated cells in a time-dependent manner. Nuclear fragmentation at $5{\mu}M$ was not detected, even though it was discovered at $20{\mu}M$. Poly (ADP-ribose) polymerase cleavages were not detected in $5{\mu}M$ within 24 hours. Massive vacuolization in the cytoplasm of $5{\mu}M$ treated cells were observed. Acridine orange stain-positive cells was increased according in time-dependence manner. The autophagosome-incorporated LC3 II protein expression was increased in $5{\mu}M$ treated cells, but was not detected in $20{\mu}M$ treated cells. The expression of GFP-LC3 were increased in $5{\mu}M$ treated cells in a time-dependent manner. Conclusion: The induction of autophagy occurred in $5{\mu}M$ dose of cisplatin-treated lung cancer cells.

• Journal of Life Science
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• v.32 no.3
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• pp.210-221
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• 2022

This study investigated the mechanisms underlying the anti-cancer effects of non-steroidal anti-inflammatory drugs (NSAIDs) in human cancer cells in combination with either N-[N-(3, 5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT), a γ-secretase inhibitor, or MHY2245, a new synthetic sirtuin 1 inhibitor. The results showed both DAPT and MHY2245 as novel chemosensitizers of human colon cancer KM12 and human hepatocellular carcinoma SNU475 cells to NSAIDs involving celecoxib and 2, 5-dimethyl celecoxib. The NSAID-induced cytotoxicity of these cells was significantly increased by DAPT and MHY2245 in a cyclooxygenase-2 independent manner. In addition, DAPT and MHY2245 reduced levels of p62, Notch1 intracellular domain, and multiple cancer stemness (CS)-related markers including Notch1, CD44, CD133, octamer-binding transcription factor 4, mutated p53 and c-Myc. However, the level of activating transcription factor 4 (ATF4) was enhanced, probably indicating the down-regulation of multiple CS-related markers by DAPT or MHY2245-mediated autophagy induction. Moreover, the NSAID-mediated reduction of p62/nuclear factor erythroid-derived 2-like 2 and CS-related marker proteins and the up-regulation of C/EBP homologous protein (CHOP)/ATF4 were accelerated by DAPT and MHY2245. As such, the combination of NSAID and either DAPT or MHY2245 resulted in higher cytotoxicity than NSAID alone by accelerating the down-regulation of multiple CS-related markers and PARP activation, indicating that both inhibitors promote NSAID-mediated autophagic cell death, possibly through the CHOP/ATF4 pathway. In conclusion, either combination strategy may be useful for the effective treatment of human cancer cells expressing CS-related markers.