• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.1
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• pp.183-189
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• 2003

Platycodi Radix, the root of Platycodon grandiflorum, commonly known as Doraji, is used as a traditional oriental medicine. Extracts from the roots of P. grandiflorum have been reported to have wide ranging health benefits. We investigated the effects of an aqueous extract from the roots of P. grandiflorum (AEPG) on the cell proliferation of human lung carcinoma A549 cells in order to understand its anti-proliferative mechanism. AEPG treatment resulted in the inhibition of cell proliferation in a concentration-dependent manner. This anti-proliferative effect of A549 cells by AEPG treatment was associated with morphological changes such as membrane shrinking, cell rounding up and inhibition of cell migration. DNA flow cytometric histograms showed that populations of both Sand G2/M phase of the cell cycle were increased by AEPG treatment in a concentration-dependent manner. AEPG treatment induced a marked accumulation of tumor suppressor p53 and a concomitant induction of cyclin-dependent kinase (Cdk) inhibitor p21 and p27. In addition, SSS treatment resulted in down-regulation of Cdk2 and Cdk4 expression. The present results indicated that AEPG-induced inhibition of lung cancer cell proliferation is associated with the blockage of S to G2/M phase progression the induction of apoptosis. Taken together, these findings suggest that P. grandiflorum has strong potential for development as an agent for prevention against human lung cancer.

• Journal of Acupuncture Research
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• v.20 no.5
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• pp.93-106
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• 2003

Objective : To investigate the possible molecular mechanism(s) of melittin as a candidate of anti-cancer drug, we examined the effects of the compound on the growth of human lung carcinoma cell line A549. Methods: MTT, morphological changes, DAPI staining, Western blot, RT-PCR and in vitro prostaglandin E2 (PGE2) accumulation assays were performed. Results: The anti-proliferative effect by melittin treatment in A549 cells was associated with morphological changes such as membrane shrinking and cell rounding up. Melittin induced apoptotic cell death in a concentration-dependent manner, which was associated with inhibition or degradation of apoptotic target proteins such as ${\beta}$-catenin, poly(ADP-ribose) polymerase(PARP) and phospholipase $C-{\gamma}1(PLC-{\gamma}1)$. Melittin treatment inhibited the expression of cyclooxygenase-2(COX-2) and accumulation of PGE2 in aconcentration-dependent fashion. In addition, Melittin treatment induced the down-regulation of telomerase reverse transcriptase(hTERT) and proto-oncogene c-myc expression of A549 cells. Conclusions: Taken together, these findings suggest that melittin-induced inhibition of human lung cancer cell proliferation is associated with the induction of apoptotic cell death via regulation of several major growth regulatory gene products, and melittin may have therapeutic potential in human lung cancer.

• IMMUNE NETWORK
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• v.13 no.5
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• pp.213-217
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• 2013

Enterotoxigenic Bacteroides fragilis (ETBF) is a human gut commensal bacteria that causes inflammatory diarrhea and colitis. ETBF also promotes colorectal tumorigenesis in the Min mouse model. The key virulence factor is a secreted metalloprotease called B. fragilis toxin (BFT). BFT induces E-cadherin cleavage, cell rounding, activation of the ${\beta}$-catenin pathway and secretion of IL-8 in colonic epithelial cells. However, the precise mechanism by which these processes occur and how these processes are interrelated is still unclear. E-cadherin form homophilic interactions which tethers adjacent cells. Loss of E-cadherin results in detachment of adjacent cells. Prior studies have suggested that BFT induces IL-8 expression by inducing E-cadherin cleavage; cells that do not express E-cadherin do not secrete IL-8 in response to BFT. In the current study, we found that HT29/C1cells treated with dilute trypsin solution induced E-cadherin degradation and IL-8 secretion, consistent with the hypothesis that E-cadherin cleavage causes IL-8 secretion. However, physical damage to the cell monolayer did not induce IL-8 secretion. We also show that EDTA-mediated disruption of E-cadherin interactions without E-cadherin degradation was sufficient to induce IL-8 secretion. Finally, we determined that HT29/C1 cells treated with LiCl (${\beta}$-catenin activator) induced IL-8 secretion in a dose-dependent and time-dependent manner. Taken together, our results suggest that BFT induced IL-8 secretion may occur by the following process: E-cadherin cleavage, disruption of cellular interactions, activation of the ${\beta}$-catenin pathway and IL-8 expression. However, we further propose that E-cadherin cleavage per se may not be required for BFT induced IL-8 secretion.

• Toxicological Research
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• v.19 no.2
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• pp.91-98
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• 2003

Alkylating agents form alkylated base adducts in the DNA and cause DNA lesions leading to cell killing. In this study, we investigated the mechanism of apoptosis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in PC-3 and DU145 human prostate carcinoma cell lines. MNNG treatment resulted in the inhibition of cell proliferation in a concentration-dependent manner to a similar extent in both cell lines. This anti-proliferative effect of PC-3 and DU145 cells by MNNG was associated with morphological changed such as membrane shrinking, cell rounding up and formation of apoptotic bodies. MNNG treatment also induced a proteolytic cleavage of specific target proteins such as poly(ADP-ribose) polymerase (PARP) and $\beta$-catenin proteins in DU145 cells but in PC-3 cells. Furthermore, we observed an increase of proapoptotic protein Bax family expression and a decrease of antiapoptotic protein Bcl-2 family by MNNG treatment in a concentration-dependent manner MNNG also induced a proteolytic activation of caspase-3 and -9, which is believed to play a central role in the apoptotic signaling pathway.

• Journal of Microbiology and Biotechnology
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• v.22 no.2
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• pp.170-175
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• 2012

Clostridium difficile toxin A glucosylates Rho family proteins, resulting in actin filament disaggregation and cell rounding in cultured colonocytes. Given that the cellular toxicity of toxin A is dependent on its receptor binding and subsequent entry into the cell, we herein sought to identify additional colonocyte proteins that might bind to toxin A following its internalization. Our results revealed that toxin A interacted with ERK1 and ERK2 in two human colonocyte cell lines (NCM460 and HT29). A GST-pulldown assay also showed that toxin A can directly bind to ERK1 and ERK2. In NCM460 cells exposed to PMA (an ERK1/2 activator), the phosphorylation of ERK1/2 did not affect the interaction between toxin A and ERK1/2. However, an in vitro kinase assay showed that the direct binding of toxin A to ERK1 or ERK2 inhibited their kinase activities. These results suggest a new molecular mechanism for the cellular toxicity seen in cells exposed to toxin A.