• BMB Reports
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• 제39권6호
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• pp.722-729
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• 2006

Recently, we have reported that 3-hydrogenkwadaphnin (3-HK), a diterpene ester isolated from Dendrostellera lessertii (Thymealeaceae), is very effective against leukemia cell lines without any detectable effects on normal cells (Moosavi et al., 2005b). In this study, we report that 3-HK induces $G_1$ cell-cycle arrest, differentiation and apoptosis in APL NB4 cell line. Indeed, the drug between 24 to 96 h induced 7-65% growth inhibition of NB4 cells. Cell viability was also decreased by 2-55% between 24 to 96 h treatments with the drug, respectively. These effects of the drug were also dose-dependent. According to flow cytomtry results, 3-HK (15 nM) induced a significant G1-arrest up to 24 h which was consequently followed with appearance of sub-$G_1$ peak at 72 to 96 h. Hoechst 33258 staining and DNA fragmentation assays confirmed the occurrence of apoptosis among the treated cells. On the other hand, NBT reducing assay, Wright-Giemsa staining, phagocytic activity and expression of cell surface markers (CD11b and CD14) confirmed that the inhibition of proliferation is associated with differentiation especially toward macrophage-like morphology. Interestingly, 3-HK at 5 and 10 nM enhanced the effects of all-trans retinoic acid (ATRA) in NB4 cells. Based on these results, 3-HK might become an ideal candidate for treatment of APL patients pending full exploration of its biological functions.

• Molecules and Cells
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• 제38권5호
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• pp.457-465
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• 2015

The 15-kDa selenoprotein (Sep15) is a selenoprotein residing in the lumen of the endoplasmic reticulum (ER) and implicated in quality control of protein folding. Herein, we established an inducible RNAi cell line that targets Sep15 mRNA in Chang liver cells. RNAi-induced Sep15 deficiency led to inhibition of cell proliferation, whereas cell growth was resumed after removal of the knockdown inducer. Sep15-deficient cells were arrested at the G1 phase by upregulating p21 and p27, and these cells were also characterized by ER stress. In addition, Sep15 deficiency led to the relocation of focal adhesions to the periphery of the cell basement and to the decrease of the migratory and invasive ability. All these changes were reversible depending on Sep15 status. Rescuing the knockdown state by expressing a silent mutant Sep15 mRNA that is resistant to siRNA also reversed the phenotypic changes. Our results suggest that SEP15 plays important roles in the regulation of the G1 phase during the cell cycle as well as in cell motility in Chang liver cells, and that this selenoprotein offers a novel functional link between the cell cycle and cell motility.

• Asian Pacific Journal of Cancer Prevention
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• 제13권7호
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• pp.3103-3107
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• 2012

Osteosarcoma, the most common primary mesenchymal malignant tumor, usually has bad prognosis in man, with cancer stem-like cells (CSCs) considered to play a critical role in tumorigenesis and drug-resistance. It is known that phosphatidylinositol 3-kinase (PI3K) is involved in regulation of tumor cell fates, such as proliferation, cell cycling, survival and apoptosis. Whether and how PI3K and inhibitors might cooperate in human osteosarcoma CSCs is still unknown. We therefore evaluated the effects of LY294002, a PI3K inhibitor, on the cell cycle and apoptosis of osteosarcoma CSCs in vitro. LY294002 prevented phosphorylation of protein kinase B (PKB/Akt) by inhibition of PI3K phosphorylation activity, thereby inducing G0/G1 cell cycle arrest and apoptosis in osteosarcoma CSCs. Further studies also demonstrated that apoptosis induction by LY294002 is accompanied by activation of caspase-9, caspase-3 and PARP, which are involved in the mitochondrial apoptosis pathway. Therefore, our results indicate PI3K inhibitors may represent a potential strategy for managing human osteosarcoma via affecting CSCs.

• 한국독성학회:학술대회논문집
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• 한국독성학회 2006년도 추계학술대회
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• pp.55-64
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• 2006

The fetal central nervous system (CNS) is sensitive to diverse environmental factors, such as alcohol, heavy metals, irradiation, mycotoxins, neurotransmitters, and DNA damage, because a large number of processes occur during an extended period of development. Fetal neural damage is an important issue affecting the completion of normal CNS development. As many concepts about the brain development have been recently revealed, it is necessary to compare the mechanism of developmental abnormalities induced by extrinsic factors with the normal brain development. To clarify the mechanism of fetal CNS damage, we used one experimental model in which 5-azacytidine (5AZC), a DNA damaging and demethylating agent, was injected to the dams of rodents to damage the fetal brain. 5AzC induced cell death (apoptosis)and cell cycle arrest in the fetal brain, and it lead to microencephaly in the neonatal brain. We investigated the mechanism of apoptosis and cell cycle arrest in the neural progenitor cells in detail, and demonstrated that various cell cycle regulators were changed in response to DNA damage. p53, the guardian of genome, played a main role in these processes. Further, using DNA microarray analysis, tile signal cascades of cell cycle regulation were clearly shown. Our results indicate that neural progenitor cells have the potential to repair the DNA damages via cell cyclearrest and to exclude highly affected cells through the apoptotic process. If the stimulus and subsequent DNA damage are high, brain development proceeds abnormally and results in malformation in the neonatal brain. Although the mechanisms of fetal brain injury and features of brain malformation afterbirth have been well studied, the process between those stages is largely unknown. We hypothesized that the fetal CNS has the ability to repair itself post-injuring, and investigated the repair process after 5AZC-induced damage. Wefound that the damages were repaired by 60 h after the treatment and developmental processes continued. During the repair process, amoeboid microglial cells infiltrated in the brain tissue, some of which ingested apoptotic cells. The expressions of genes categorized to glial cells, inflammation, extracellular matrix, glycolysis, and neurogenesis were upregulated in the DNA microarray analysis. We show here that the developing brain has a capacity to repair the damage induced by the extrinsic stresses, including changing the expression of numerous genes and the induction of microglia to aid the repair process.

• Biomolecules & Therapeutics
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• 제30권1호
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• pp.72-79
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• 2022

Licochalcone H (LCH) is a phenolic compound synthetically derived from licochalcone C (LCC) that exerts anticancer activity. In this study, we investigated the anticancer activity of LCH in human skin cancer A375 and A431 cells. The 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) cell viability assay was used to evaluate the antiproliferative activity of LCH. Cell cycle distribution and the induction of apoptosis were analyzed by flow cytometry. Western blotting assays were performed to detect the levels of proteins involved in cell cycle progression, apoptosis, and the JAK2/STAT3 signaling pathway. LCH inhibited the growth of cells in dose- and time-dependent manners. The annexin V/propidium iodide double staining assay revealed that LCH induced apoptosis, and the LCH-induced apoptosis was accompanied by cell cycle arrest in the G1 phase. Western blot analysis showed that the phosphorylation of JAK2 and STAT3 was decreased by treatment with LCH. The inhibition of the JAK2/STAT3 signaling pathway by pharmacological inhibitors against JAK2/STAT3 (cryptotanshinone (CTS) and S3I-201) simulated the antiproliferative effect of LCH suggesting that LCH induced apoptosis by modulating JAK2/STAT3 signaling.

• Journal of Periodontal and Implant Science
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• 제49권3호
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• pp.138-147
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• 2019

Purpose: Several studies have shown that the oral cavity is a secondary location for Helicobacter pylori colonization and that H. pylori is associated with the severity of periodontitis. This study investigated whether H. pylori had an effect on the periodontium. We established an invasion model of a standard strain of H. pylori in human periodontal ligament fibroblasts (hPDLFs), and evaluated the effects of H. pylori on cell proliferation and cell cycle progression. Methods: Different concentrations of H. pylori were used to infect hPDLFs, with 6 hours of co-culture. The multiplicity of infection in the low- and high-concentration groups was 10:1 and 100:1, respectively. The Cell Counting Kit-8 method and Ki-67 immunofluorescence were used to detect cell proliferation. Flow cytometry, quantitative real-time polymerase chain reaction, and western blots were used to detect cell cycle progression. In the high-concentration group, the invasion of H. pylori was observed by transmission electron microscopy. Results: It was found that H. pylori invaded the fibroblasts, with cytoplasmic localization. Analyses of cell proliferation and flow cytometry showed that H. pylori inhibited the proliferation of periodontal fibroblasts by causing G2 phase arrest. The inhibition of proliferation and G2 phase arrest were more obvious in the high-concentration group. In the low-concentration group, the G2 phase regulatory factors cyclin dependent kinase 1 (CDK1) and cell division cycle 25C (Cdc25C) were upregulated, while cyclin B1 was inhibited. However, in the high-concentration group, cyclin B1 was upregulated and CDK1 was inhibited. Furthermore, the deactivated states of tyrosine phosphorylation of CDK1 (CDK1-Y15) and serine phosphorylation of Cdc25C (Cdc25C-S216) were upregulated after H. pylori infection. Conclusions: In our model, H. pylori inhibited the proliferation of hPDLFs and exerted an invasive effect, causing G2 phase arrest via the Cdc25C/CDK1/cyclin B1 signaling cascade. Its inhibitory effect on proliferation was stronger in the high-concentration group.

• The Korean Journal of Physiology and Pharmacology
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• 제1권4호
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• pp.457-466
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• 1997

The effects of DFMO or/and putrescine on the dexamethasone-induced apoptosis of CEM cells were studied to investigate the role of polyamines in anti-leukemic glucocorticoid action. Dexamethasone- induced apoptosis was preceded by significant decreases of cellular polyamine contents and putrescine uptake activity. But DFMO produced decreases of putrescine and spermidine contents and marked increase of putrescine uptake activity, but did not induce apoptosis. However, dexamethasone and DFMO, respectively, induced $G_1-arrest$ in cell cycle and hypophosphorylation of pRb, resulting in the increase of $G_1$ to S ratio and decrease of CEM cell count. DFMO enhanced the dexamethasone-induced apoptosis and $G_1-arrest$. On the other hand, putrescine little affected the apoptotic and $G_1-arresting$ activities of dexamethasone, but almost suppress the effects of DFMO and also the DFMO-dependent enhancement of dexamethasone effects. These results suggested that the dexamethasone-induced apoptosis to be associated with pRb hypophosphorylation and $G_1-arrest$ in CEM cells might be ascribed to the concomitant decreases of cellular polyamine contents and putrescine uptake activity.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2003년도 2003 Annual Meeting, BioExhibition and International Symposium
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• pp.117-118
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• 2003

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3454-3456
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• 2010

• 한국환경성돌연변이발암원학회:학술대회논문집
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• 한국환경성돌연변이발암원학회 2004년도 춘계학술대회
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• pp.62-62
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• 2004