• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.10a
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• pp.101-101
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• 2018

Resveratrol is a polyphenolic compound, which is a naturally occurring phytochemical and is found in a variety of plants, including food such as grapes, berries and peanuts. Although several studies have demonstrated that resveratrol possesses anti-cancer activity against various types of human cancer, the molecular mechanisms of resveratrol-mediated overcome drug resistance potential are unclear. In this study, we determined whether resveratrol attenuates drug resistance responses in 5-fluorouracil-resistant colon cancer (SNUC5/5-FUR) cells. Treatment with resveratrol significantly enhanced apoptosis in a concentration-dependent manner, which was associated with the modulation of anti- and/or pro-apoptotic protein expression, activation of caspases and activation of AMP-activated protein kinase. Resveratrol treatment also increased the induction of autophagy through up-regulation of autophagy-related genes such as Microtubule-associated protein 1A/1B-light chain 3, P62 and beclin-1. However, blocking of autophagy by bafilomycin A1 reduced apoptotic cell death, suggesting that resveratrol-induced autophagy functions as a cell death mechanism in SNUC5/5-FU cells. Although the further studies are needed, these findings suggest that resveratrol may have therapeutic potential to overcome drug resistance in colon cancer patients.

• Journal of Physiology & Pathology in Korean Medicine
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• v.24 no.6
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• pp.942-949
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• 2010

Morus alba L., a kind of Oriental medicinal herbs, has been traditionally used to treat pulmonary asthma and congestion. According to recent studies, extracts of M. alba L. have showed anti-inflammatory, anti-oxidant, anti-tumor and hypoglycemic effects. However, the molecular mechanisms on how it acts as a death-inducer in cancer cells have not been fully understood. In this study, we investigated the cell death effects of methylene chloride extracts of M. alba L. (MEMA) in A549 human lung carcinoma cells. It was shown that MEMA induced the apoptotic cell death proved by increased sub-G1 phase cell population, apoptotic body formation and chromatin condensation. MEMA treatment induced the expression of death receptor-related proteins such as death receptor (DR) 4, DR5, Fas and FasL, which further triggered the activation of caspase-8 and the cleavage of Bid in a concentration-dependent manner. However, MEMA reduced anti-apoptotic Bcl-2 and Bcl-xL expression which contributed to the loss of mitochondrial membrane potential (MMP), and the activations of caspase-9 and caspase-3. Meanwhile, the morphological study indicated a characteristic finding of autophagy, such as the formation of autophagosomes in MEMA-treated cells. Furthermore, markers of autophagy, namely, the increased MDC-positive cells, conversion of microtubule-associated protein light chain 3 (LC3)-I to LC3-II and increased beclin-1 accumulation, were observed. Taken together, these findings demonstrated that MEMA triggered both autophagy and apoptosis in A549 cancer cells. They might suggest that M. alba L. could be a prospective clinical application to treat human lung cancers.

• Molecules and Cells
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• v.46 no.8
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• pp.476-485
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• 2023

Gastric cancer stem-like cells (GCSCs) possess stem cell properties, such as self-renewal and tumorigenicity, which are known to induce high chemoresistance and metastasis. These characteristics of GCSCs are further enhanced by autophagy, worsening the prognosis of patients. Currently, the mechanisms involved in the induction of stemness in GCSCs during autophagy remain unclear. In this study, we compared the cellular responses of GCSCs with those of gastric cancer intestinal cells (GCICs) whose stemness is not induced by autophagy. In response to glucose starvation, the levels of β-catenin and stemness-related genes were upregulated in GCSCs, while the levels of β-catenin declined in GCICs. The pattern of deubiquitinase ubiquitin C-terminal hydrolase-L3 (UCH-L3) expression in GCSCs and GCICs was similar to that of β-catenin expression depending on glucose deprivation. We also observed that inhibition of UCH-L3 activity reduced β-catenin protein levels. The interaction between UCH-L3 and β-catenin proteins was confirmed, and it reduced the ubiquitination of β-catenin. Our results suggest that UCH-L3 induces the stabilization of β-catenin, which is required to promote stemness during autophagy activation. Also, UCH-L3 expression was regulated by c-Fos, and the levels of c-Fos increased in response to autophagy activation. In summary, our findings suggest that the inhibition of UCH-L3 during nutrient deprivation could suppress stress resistance of GCSCs and increase the survival rates of gastric cancer patients.

• Journal of Life Science
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• v.31 no.10
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• pp.873-884
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• 2021

The purpose of present study is to investigate the role of artesunate (ART) in enhancing anticancer effect of nonsteroidal anti-inflammatory drug (NSAID) on human cancer cells, and we elucidate a possible molecular mechanism of this combination effect. We showed that the combined effect of ART with NSAID such as celecoxib (CCB) or dimethyl-CCB (DMC) in various type of human cancer cells. After ART treatment, the expression of p62, nuclear factor erythroid 2-like 2 (NRF2) and cancer stemness (CS)-related proteins including CD44, CD133, aldehyde dehydrogenase 1 (ALDH1), octamer-binding transcription factor 4 (Oct4), mutated p53 (mutp53) and c-Myc was down-regulated. ART induced autophagy as reduction of the autophagy receptor p62, which was associated with up-regulation of activating transcription factor 4 (ATF4) and C/EBP homologous protein (CHOP), and simultaneous down-regulation of NRF2 and CS-related proteins was occurred in the human cancer cells. These results indicate a possibility that ART activates autophagy through ATF4-CHOP cascade leading to down-regulation of CS-related proteins and subsequently eradicated cancer stem cells. In addition, co-treatment with ART and imatinib was more effective than either drug alone on growth inhibition and apoptosis induction of cancer cells. In conclusion, induction of autophagy-dependent cell death by ART might play a critical role in mediating the synergistic effect of drug combination (ART/NSAID and ART/imatinib). Therefore, ART could be a promising candidate as a chemosensitizer to enhance the anticancer effects of NSAID and imatinib.

• Parasites, Hosts and Diseases
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• v.51 no.5
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• pp.497-502
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• 2013

Autophagy-related protein 8 (Atg8) is an essential component of autophagy formation and encystment of cystforming parasites, and some protozoa, such as, Acanthamoeba, Entamoeba, and Dictyostelium, have been reported to possess a type of Atg8. In this study, an isoform of Atg8 was identified and characterized in Acanthamoeba castellanii (AcAtg8b). AcAtg8b protein was found to encode 132 amino acids and to be longer than AcAtg8 protein, which encoded 117 amino acids. Real-time PCR analysis showed high expression levels of AcAtg8b and AcAtg8 during encystation. Fluorescence microscopy demonstrated that AcAtg8b is involved in the formation of the autophagosomal membrane. Chemically synthesized siRNA against AcAtg8b reduced the encystation efficiency of Acanthamoeba, confirming that AcAtg8b, like AcAtg8, is an essential component of cyst formation in Acanthamoeba. Our findings suggest that Acanthamoeba has doubled the number of Atg8 gene copies to ensure the successful encystation for survival when 1 copy is lost. These 2 types of Atg8 identified in Acanthamoeba provide important information regarding autophagy formation, encystation mechanism, and survival of primitive, cyst-forming protozoan parasites.

• BMB Reports
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• v.49 no.10
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• pp.529-535
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• 2016

The NLRP3 inflammasome is activated by a variety of external or host-derived stimuli and its activation initiates an inflammatory response through caspase-1 activation, resulting in inflammatory cytokine IL-1β maturation and secretion. The NLRP3 inflammasome activation is a kind of innate immune response, most likely mediated by myeloid cells acting as a host defense mechanism. However, if this activation is not properly regulated, excessive inflammation induced by overactivated NLRP3 inflammasome can be detrimental to the host, causing tissue damage and organ dysfunction, eventually causing several diseases. Previous studies have suggested that mitochondrial damage may be a cause of NLRP3 inflammasome activation and autophagy, which is a conserved self-degradation process that negatively regulates NLRP3 inflammasome activation. Recently, mitochondria-selective autophagy, termed mitophagy, has emerged as a central player for maintaining mitochondrial homeostasis through the elimination of damaged mitochondria, leading to the prevention of hyperinflammation triggered by NLRP3 inflammasome activation. In this review, we will first focus on the molecular mechanisms of NLRP3 inflammasome activation and NLRP3 inflammasome-related diseases. We will then discuss autophagy, especially mitophagy, as a negative regulator of NLPP3 inflammasome activation by examining recent advances in research.

• BMB Reports
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• v.56 no.12
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• pp.651-656
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• 2023

Senescence, a cellular process through which damaged or dysfunctional cells suppress the cell cycle, contributes to aging or age-related functional decline. Cell metabolism has been closely correlated with aging processes, and it has been widely recognized that metabolic changes underlie the cellular alterations that occur with aging. Here, we report that fatty acid oxidation (FAO) serves as a critical regulator of cellular senescence and uncover the underlying mechanism by which FAO inhibition induces senescence. Pharmacological or genetic ablation of FAO results in a p53-dependent induction of cellular senescence in human fibroblasts, whereas enhancing FAO suppresses replicative senescence. We found that FAO inhibition promotes cellular senescence through acetyl-CoA, independent of energy depletion. Mechanistically, increased formation of autophagosomes following FAO inhibition leads to a reduction in SIRT1 protein levels, thereby contributing to senescence induction. Finally, we found that inhibition of autophagy or enforced expression of SIRT1 can rescue the induction of senescence as a result of FAO inhibition. Collectively, our study reveals a distinctive role for the FAO-autophagy-SIRT1 axis in the regulation of cellular senescence.

• International Journal of Oral Biology
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• v.45 no.1
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• pp.1-7
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• 2020

Oral lichen planus (OLP) is a chronic inflammatory disease observed in approximately 0.5-2.2% of the population, and it is recognized as a premalignant lesion that can progress into oral squamous cell carcinoma (OSCC). The rate of malignant transformation is approximately 1.09-2.3%, and the risk factors for malignant transformation are age, female, erosive type, and tongue site location. Malignant transformation of OLP is likely related to the low frequency of apoptotic phenomena. Therefore, apoptosis-related genetic factors, like p53, BCL-2, and BAX are reviewed. Increased p53 expression and altered expression of BCL-2 and BAX were observed in OLP patients, and the malignant transformation rate in these patients was relatively higher. The involvement of microRNA (miRNA) in the malignant transformation of OLP is also reviewed. Because autophagy is involved in cell survival and death through the regulation of various cellular processes, autophagy-related genetic factors may function as factors for malignant transformation. In OLP, decreased levels of ATG9B mRNA and a higher expression of IGF1 were observed, suggesting a reduction in cell death and autophagic response. Activated IGF1-PI3K/AKT/mTor cascade may play an important role in a signaling pathway related to the malignant transformation of OLP to OSCC. Recent research has shown that miRNAs, such as miR-199 and miR-122, activate the cascade, increasing the prosurvival and proproliferative signals.

• Journal of Life Science
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• v.23 no.10
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• pp.1280-1287
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• 2013

The current study investigated the effects of [6]-gingerol, a ginger phytochemical, on the expression of autophagy-related genes and the activation of antioxidative enzymes in the pancreas of mice with cerulein-induced acute pancreatitis. The following were studied: pancreatic edema, ${\alpha}$-amylase activity in serum, expression of autophagy genes, activities of antioxidative defense enzymes, such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and the production of lipid peroxidation (LPO). The results revealed that cerulein-induced edema in the pancreas and ${\alpha}$-amylase activity in the cerulein group significantly increased compared with that of the control. However, that of the [6]-gingerol pretreated group was significantly decreased compared with that of the cerulein-alone injected group (positive control). There was no significant difference compared with that of control. The expression of autophagy-related proteins, including Beclin-1 and cleaved microtubule-associated protein 1 light chain 3, were significantly increased in the positive control but significantly decreased in the [6]-gingerol-pretreated group. Furthermore, the activities of SOD and GSH-Px in the positive control were decreased compared with those of the control. However, those of the [6]-gingerol pretreated group were significantly increased compared with those of the cerulein-alone group. The mRNA levels and antioxidant enzyme activities were similar. The production of LPO in the cerulein with and without [6]-gingerol groups was increased by 133.1% and 26.3%, respectively, compared with that of the control, whereas that of the [6]-gingerol-pretreated group was significantly decreased by 48.5% compared with that of the positive control. Therefore, [6]-gingerol may be a strong candidate in reducing autophagy and LPO production and in enhancing antioxidative enzyme activities to help prevent acute and chronic pancreatitis.

• Biomolecules & Therapeutics
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• v.28 no.2
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• pp.202-210
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• 2020

Fluoxetine is used widely as an antidepressant for the treatment of cancer-related depression, but has been reported to also have anti-cancer activity. In this study, we investigated the cytotoxicity of fluoxetine to human gastric adenocarcinoma cells; as shown by the MTT assay, fluoxetine induced cell death. Subsequently, cells were treated with 10 or 20 µM fluoxetine for 24 h and analyzed. Apoptosis was confirmed by the increased number of early apoptotic cells, shown by Annexin V- propidium iodide staining. Nuclear condensation was visualized by DAPI staining. A significant increase in the expression of cleaved PARP was observed by western blotting. The pan-caspase inhibitor Z-VAD-FMK was used to detect the extent of caspase-dependent cell death. The induction of autophagy was determined by the formation of acidic vesicular organelles (AVOs), which was visualized by acridine orange staining, and the increased expression of autophagy markers, such as LC3B, Beclin 1, and p62/SQSTM 1, observed by western blotting. The expression of upstream proteins, such as p-Akt and p-mTOR, were decreased. Autophagic degradation was evaluated by using bafilomycin, an inhibitor of late-stage autophagy. Bafilomycin did not significantly enhance LC3B expression induced by fluoxetine, which suggested autophagic degradation was impaired. In addition, the co-administration of the autophagy inhibitor 3-methyladenine and fluoxetine significantly increased fluoxetine-induced apoptosis, with decreased p-Akt and markedly increased death receptor 4 and 5 expression. Our results suggested that fluoxetine simultaneously induced both protective autophagy and apoptosis and that the inhibition of autophagy enhanced fluoxetine-induced apoptosis through increased death receptor expression.