• BMB Reports
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• v.56 no.10
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• pp.557-562
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• 2023

Dysregulation of the E3 ubiquitin ligase Parkin has been linked to various human cancers, indicating that Parkin is a tumor suppressor protein. However, the mechanisms of action of Parkin remain unclear to date. Thus, we aimed to elucidate the mechanisms of action of Parkin as a tumor suppressor in human lung and colorectal cancer cells. Results showed that Parkin overexpression reduced the viability of A549 human lung cancer cells by inducing G2/M cell cycle arrest. In addition, Parkin caused DNA damage and ATM (Ataxia telangiectasia mutated) activation, which subsequently led to p53 activation. It also induced the p53-mediated upregulation of p21 and downregulation of cyclin B1. Moreover, Parkin suppressed the proliferation of HCT-15 human colorectal cancer cells by a mechanism similar to that in A549 lung cancer cells. Taken together, our results suggest that the tumor-suppressive effects of Parkin on lung and colorectal cancer cells are mediated by DNA damage/p53 activation/cyclin B1 reduction/cell cycle arrest.

• The Korean Journal of Zoology
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• v.12 no.1
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• pp.22-28
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• 1969

In order to see if any suppressor system for the SD action was involved in natural populations of D. melanogaster samples from the populations of nine localities in Korea, Choonchun, Yusoo, Namhai, Shinchon(Seoul), Kwangjoo(Kyunggi), Koonsan, Kwangjoo(Chunnam), Jejoo and Pusan were analyzed by using the mating scheme for locating the suppressor on chromosome pairs. And also two kinds of recombinant SD lines R-1, the American line and $R(SD^NH -1)-1$, the Japanese one were used in order to see any difference of the response of the suppressor for differently originated SD. The results of the experiment are given below. (1) The suppressor system was involved in all lines of natural populations from nine localities of Korea. (2) Most of the suppressors were found to be located on the X chromosome and only a few lines from three populations showed to carry the suppressors on the second chromosome and on the third or fourth chromosoem. (3) The response of the suppressor for differently originated SD lines showed no significant difference.

• IMMUNE NETWORK
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• v.21 no.3
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• pp.21.1-21.22
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• 2021

Myeloid-derived suppressor cells (MDSCs) have strong immunosuppressive activity and are morphologically similar to conventional monocytes and granulocytes. The development and classification of these cells have, however, been controversial. The activation network of MDSCs is relatively complex, and their mechanism of action is poorly understood, creating an avenue for further research. In recent years, MDSCs have been found to play an important role in immune regulation and in effectively inhibiting the activity of effector lymphocytes. Under certain conditions, particularly in the case of tissue damage or inflammation, MDSCs play a leading role in the immune response of the central nervous system. In cancer, however, this can lead to tumor immune evasion and the development of related diseases. Under cancerous conditions, tumors often alter bone marrow formation, thus affecting progenitor cell differentiation, and ultimately, MDSC accumulation. MDSCs are important contributors to tumor progression and play a key role in promoting tumor growth and metastasis, and even reduce the efficacy of immunotherapy. Currently, a number of studies have demonstrated that MDSCs play a key regulatory role in many clinical diseases. In light of these studies, this review discusses the origin of MDSCs, the mechanisms underlying their activation, their role in a variety of clinical diseases, and their function in immune response regulation.

• Journal of Gastric Cancer
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• v.14 no.3
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• pp.147-155
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• 2014

Homeostatic imbalance between cell proliferation and death in gastric mucosal epithelia may lead to gastritis and gastric cancer. Despite abundant gastrokine 1 (GKN1) expression in the normal stomach, the loss of GKN1 expression is frequently detected in gastric mucosa infected with Helicobacter pylori, as well as in intestinal metaplasia and gastric cancer tissues, suggesting that GKN1 plays an important role in gastric mucosal defense, and the gene functions as a gastric tumor suppressor. In the stomach, GKN1 is involved in gastric mucosal inflammation by regulating cytokine production, the nuclear factor-${\kappa}B$ signaling pathway, and cyclooxygenase-2 expression. GKN1 also inhibits the carcinogenic potential of H. pylori protein CagA by binding to it, and up-regulates antioxidant enzymes. In addition, GKN1 reduces cell viability, proliferation, and colony formation by inhibiting cell cycle progression and epigenetic modification by down-regulating the expression levels of DNMT1 and EZH2, and DNMT1 activity, and inducing apoptosis through the death receptor-dependent pathway. Furthermore, GKN1 also inhibits gastric cancer cell invasion and metastasis via coordinated regulation of epithelial mesenchymal transition-related protein expression, reactive oxygen species production, and PI3K/Akt signaling pathway activation. Although the modes of action of GKN1 have not been clearly described, recent limited evidence suggests that GKN1 acts as a gastricspecific tumor suppressor. This review aims to discuss, comment, and summarize the recent progress in the understanding of the role of GKN1 in gastric cancer development and progression.

• Environmental Mutagens and Carcinogens
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• v.25 no.3
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• pp.118-123
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• 2005

Nicotine has been implicated as a potential factor in the pathogenesis of human lung cancer, however its mechanism of action in the development of lung cancer remains largely unknown. To explore the role of nicotine in the development of lung cancer, we first investigated the effects of nicotine on the expression of tumor associated genes by treating Sprague-Dawley rats with nicotine (10 mg/kg) by gavage once daily for 10 days. We determined the expression of proteins and mRNAs of the ras, raf, myc, jun, fos oncogenes and p53, Rb tumor suppressor genes by Western and Northern blotting, respectively. We did not detect any changes on the levels of proteins and mRNAs of these tumor associated genes in the lung of Sprague-Dawley rats from 3 days to 12 weeks after the last treatment of nicotine, indicating that nicotine appears to have no effect on expression of these oncogenes and tumor suppressor genes at an early stage in multistage chemical carcinogenesis. In a second experiment, we investigated the possibility that 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) could be formed endogenously by treating with nicotine and sodium nitrite. We treated groups of Fischer 344 rats with nicotine ($60{\mu}mol/kg$) and sodium nitrite ($180{\mu}mol/kg$), nicotine, sodium nitrite and NNK (120 nmol/kg) alone by gavage once daily for 7 days, respectively and determined the 8-hydroxydeoxyguanosine (8-OHdG), as an indicator of NNK formation, in the lungs of rats 24 hours and 48 hours after the last treatment by HPLC/ECD method. We detect increased level of 8-OHdG in the lungs of rats treated with NNK, but in the case of nicotine plus sodium nitrite, nicotine and sodium nitrite alone we could not detected any changes of 8-OHdG, respectively.

• Journal of Pharmacopuncture
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• v.13 no.1
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• pp.37-43
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• 2010

Objective : Ginseng is one of most widely used herbal medicine. Ginseng showed anti-metastasis activities. However, its molecular mechanisms of action are unknown. So we want to report the wild ginseng repress which plays key roles in neoplastic epithelial-mesenchymal transition process. Methods : Treatment of the human colorectal carcinoma LOVO cells and human gastric carcinoma SNU601 cells with the increased concentrations of cultivated wild ginseng extracts resulted in a gradual decrease in the AXIN2 gene expression. Results : Metastasis-suppressor genes, maspin and nm23 was not affected by the treatment of ginseng extracts in LOVO cells. Moreover, the mountain cultivated wild ginseng or mountain wild ginseng are similar in their inhibitory effects on the expression of AXIN2 gene, but are substantially stronger than cultivated ginseng. Conclusion : We described the novel mechanism of wild ginseng-induced anti-metastasis activity by repressing the expression of AXIN2 gene that plays key roles in epithelial-mesenchymal transition process.

• YAKHAK HOEJI
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• v.39 no.6
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• pp.689-694
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• 1995

Sphingolipids play important roles in cell regulation and signal transduction. Recently, a sphinogomyelin cycle has been described in which activation of neutral sphingomyelinase leads to the breakdown of sphingomyelin and the generation of ceramide. Ceramide, in turn, has emerged as a candidate intracellular mediator for the action of certain cell agonists and has multiple biologic actions. Ceramide is a potent suppressor of cell growth and an inducer of apoptosis. The present studies show that exposure of IM-9 cells to ceramide resulted in internucleosomal cleavage of DNA, yielding laddered patterns of oligonucleosomal fragments characteristic of apoptosis. DNA fragmentation induced by ceramide was also confirmed by diphenylamine assay. The effect of ceramide on cell cycle progression was also studied. The addition of ceramide increase G$_{1}$ phase distribution in cell cycle. Cell cycle-related cyclin D$_{1}$ gene expression was decreased in a time-dependent manner. These results suggest that apoptosis induced by ceramide is related to cell cycle associated with the alteration of cell cycle in IM-9 cells.

• The Plant Pathology Journal
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• v.27 no.4
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• pp.315-323
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• 2011

Soybean plants infected with Bean pod mottle virus (BPMV) develop acute symptoms that usually decrease in severity over time. In other plant-virus interactions, this type of symptom recovery has been associated with degradation of viral RNAs by RNA silencing, which is accompanied by the accumulation of virus-derived small interfering RNAs (siRNAs). In this study, changes in the accumulation of BPMV siRNAs were investigated in soybean plants infected with BPMV alone, or infected with both BPMV and Soybean mosaic virus (SMV) and in transgenic soybean plants expressing SMV helper component-protease (HC-Pro). In many potyviruses, HC-Pro is a potent suppressor of RNA silencing. In plants infected with BPMV alone, accumulation of siRNAs was positively correlated with symptom severity and accumulation of BPMV genomic RNAs. Plants infected with both BPMV and SMV and BPMV-infected transgenic soybean plants expressing SMV HC-Pro exhibited severe symptoms characteristic of BPMVSMV synergism, and showed enhanced accumulation of BPMV RNAs and siRNAs compared to plants infected with BPMV alone and nontransgenic plants. Likewise, SMV HC-Pro enhanced the accumulation of siRNAs produced from a silenced green fluorescent protein gene in transient expression assays, while the P19 silencing suppressor of Tomato bushy stunt virus did not. Consistent with the modes of action of HC-Pro in other systems, which have shown that HC-Pro suppresses RNA silencing by preventing the unwinding of duplex siRNAs and inhibiting siRNA methylation, these studies showed that SMV HC-Pro interfered with the activities of RNA-induced silencing complexes, but not the activities of Dicer-like enzymes in antiviral defenses.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.3
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• pp.819-825
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• 2003

pharbitis nil and Taraxacum mongolicum are representative herbs that have been used for cancer treatment in Korean traditional medicine. To understand the molecular basis of the antitumor function, we analyzed the effect of these herbs on proliferation and apoptosis of tumor cells using a gastric cancer cell line AGS. Cell counting assay showed that pharbitis nil strongly inhibit cell proliferation Of AGS whereas Taraxacum mongolicum exhibit no detectable effect on cellular growth. [³H]thymidine uptake analysis also demonstrated that DNA replication of AGS is suppressed in a dose-dependent manner by treatment with pharbitis nil. Additionally, tryphan blue exclusion assay showed that Pharbitis nil induce apoptotic cell death of AGS in a dose-dependent. To explore whether anti antiproliferative and/or proapototic property of Pharbitis nil is associated with their effect on gene expression, we performed RT-PCR analysis of cell cycle- and apoptosis-related genes. Interestingly, mRNA expression levels of c-Jun, c-Fos, c-Myc, and Cyclin D1 were markedly reduced by Pharbitis nil. Taraxacum mongolicum also showed inhibitory action on expression of these growth-promoting protooncogene but there effects are less significant, as compared to Pharbitis nil. Furthermore, it was also found that Pharbitis nil activates expression of the p53 tumor suppressor and its downstream effector p21Waf1, which induce G1 cell cycle arrest and apoptosis. Collectively, our data demonstrate that Pharbitis nil induce growth inhibition and apoptosis of human gastric cancer cells and these effects are accompanied with down-and up-regulation of growth-regulating protooncogenes and tumor suppressor genes, respectively. This observation thus suggests that the anticancer effect of Pharbitis nil might be associated with its regulatory capability of tumor-related gene expression.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.17
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• pp.7467-7471
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• 2014

SCY1-like 1-binding protein 1 (SCYL1BP1) is a newly identified transcriptional activator domain containing protein with many unknown biological functions. Recently emerging evidence has revealed that it is a novel regulator of the p53 pathway, which is very important for the development of human cancer. However, the effects of SCYL1BP1 on human lung squamous carcinoma cell biological behavior remain poorly understood. In this study, we present evidence that SCYL1BP1 can promote the degradation of MDM2 protein and further inhibit the G1/S transition of lung squamous carcinoma cell lines. Functional assays found that reintroduction of SCYL1BP1 into lung squamous carcinoma cell lines significantly inhibited cell proliferation, migration, invasion and tumor formation in nude mice, suggesting strong tumor suppressive function of SCYL1BP1 in lung squamous carcinoma. Taken together, our data suggest that the interaction of SCYL1BP1/MDM2 could accelerate MDM2 degradation, and may function as an important tumor suppressor in lung squamous carcinomas.