• Biomolecules & Therapeutics
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• v.24 no.1
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• pp.9-18
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• 2016

Bone matrix is properly maintained by osteoclasts and osteoblasts. In the tumor microenvironment, osteoclasts are increasingly differentiated by the various ligands and cytokines secreted from the metastasized cancer cells at the bone metastasis niche. The activated osteoclasts generate osteolytic lesions. For this reason, studies focusing on the differentiation of osteoclasts are important to reduce bone destruction by tumor metastasis. The N-myc downstream-regulated gene 2 (NDRG2) has been known to contribute to the suppression of tumor growth and metastasis, but the precise role of NDRG2 in osteoclast differentiation induced by cancer cells has not been elucidated. In this study, we demonstrate that NDRG2 expression in breast cancer cells has an inhibitory effect on osteoclast differentiation. RAW 264.7 cells, which are monocytic preosteoclast cells, treated with the conditioned media (CM) of murine breast cancer cells (4T1) expressing NDRG2 are less differentiated into the multinucleated osteoclast-like cells than those treated with the CM of 4T1-WT or 4T1-mock cells. Interestingly, 4T1 cells stably expressing NDRG2 showed a decreased mRNA and protein level of intercellular adhesion molecule 1 (ICAM1), which is known to enhance osteoclast maturation. Osteoclast differentiation was also reduced by ICAM1 knockdown in 4T1 cells. In addition, blocking the interaction between soluble ICAM1 and ICAM1 receptors significantly decreased osteoclastogenesis of RAW 264.7 cells in the tumor environment. Collectively, these results suggest that the reduction of ICAM1 expression by NDRG2 in breast cancer cells decreases osteoclast differentiation, and demonstrate that excessive bone resorption could be inhibited via ICAM1 down-regulation by NDRG2 expression.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.13
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• pp.5181-5186
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• 2014

Tumors have evolved numerous mechanisms by which they can escape from immune surveillance. One of these is to produce immunosuppressive cytokines. Transforming growth factor-${\beta}$(TGF-${\beta}$) is a pleiotropic cytokine with a crucial function in mediating immune suppression, especially in the tumor microenvironment. TGF-${\beta}$ produced by T cells has been demonstrated as an important factor for suppressing antitumor immune responses, but the role of tumor-derived TGF-${\beta}$ in this process is poorly understood. In this study, we demonstrated that knockdown of tumor-derived TGF-${\beta}$ using shRNA resulted in dramatically reduced tumor size, slowing tumor formation, prolonging survival rate of tumor-bearing mice and inhibiting metastasis. We revealed possible underlying mechanisms as reducing the number of myeloid-derived suppressor cells (MDSC) and $CD4^+Foxp3^+$ Treg cells, and consequently enhanced IFN-${\gamma}$ production by CTLs. Knockdown of tumor-derived TGF-${\beta}$ also significantly reduced the conversion of na$\ddot{i}$ve $CD4^+$ T cells into Treg cells in vitro. Finally, we found that knockdown of TGF-${\beta}$ suppressed cell migration, but did not change the proliferation and apoptosis of tumor cells in vitro. In summary, our study provided evidence that tumor-derived TGF-${\beta}$ is a critical factor for tumor progression and evasion of immune surveillance, and blocking tumor-derived TGF-${\beta}$ may serve as a potential therapeutic approach for cancer.

• Biomolecules & Therapeutics
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• v.13 no.3
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• pp.143-149
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• 2005

We have demonstrated previously on a replication incompetent recombinant adenoviral vector, AdLPCD, in which the expression of cytosine deaminase (CD) gene is driven by the tumor-specific L-plastin promoter. The object of this study was to evaluate the efficacy of AdLPCD together with 5-fluorocytosine (5-FC) in suppression of the growth of established human tumor cells of ovary, Consistent with the knowledge that infection of OVCAR-3 cells with AdLPCD resulted in expression of a functional intracellular CD enzyme capable of converting 5-FC to 5-fluorouracil (5-FU) (Chung and Deisseroth, 2004), statistically significant differences in cytotoxicity were observed when AdLPCD infected cells were also exposed to 5-FC for 6 days (p=0.05), 9 days (p<0.0005) and 12 days (p<0.005), compared to 5-FC exposure alone, These results indicate that the CD gene delivered by adenoviral vector could efficiently sensitize OVCAR-3, otherwise non-toxic 5-FC. On the other hand, SKOV-3 cells, an ovarian carcinoma cell line, were more resistant to the CD/5-FC strategy compared with OVCAR-3 cells under the same condition. The results of present study suggest that the replacement of 5-FU with CD/5-FC in combination chemotherapy would be less toxic and much greater cytotoxicity than the conventional combination chemotherapy in some patients.

• Genomics & Informatics
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• v.11 no.4
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• pp.164-173
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• 2013

Genomic instability, which occurs through both genetic mechanisms (underlying inheritable phenotypic variations caused by DNA sequence-dependent alterations, such as mutation, deletion, insertion, inversion, translocation, and chromosomal aneuploidy) and epigenomic aberrations (underlying inheritable phenotypic variations caused by DNA sequence-independent alterations caused by a change of chromatin structure, such as DNA methylation and histone modifications), is known to promote tumorigenesis and tumor progression. Mechanisms involve both genomic instability and epigenomic aberrations that lose or gain the function of genes that impinge on tumor suppression/prevention or oncogenesis. Growing evidence points to an epigenome-wide disruption that involves large-scale DNA hypomethylation but specific hyper-methylation of tumor suppressor genes, large blocks of aberrant histone modifications, and abnormal miRNA expression profile. Emerging molecular details regarding the modulation of these epigenetic events in cancer are used to illustrate the alterations of epigenetic molecules, and their consequent malfunctions could contribute to cancer biology. More recently, intriguing evidence supporting that genetic and epigenetic mechanisms are not separate events in cancer has been emerging; they intertwine and take advantage of each other during tumorigenesis. In addition, we discuss the collusion between epigenetics and genetics mediated by heterochromatin protein 1, a major component of heterochromatin, in order to maintain genome integrity.

• Biomolecules & Therapeutics
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• v.19 no.4
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• pp.411-418
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• 2011

Ginsenoside Rp1 (G-Rp1) is a novel ginseng saponin derivative with anti-tumor activity. However, the biochemical and molecular mechanisms of G-Rp1 on anti-tumor activity are not fully understood. In the present study, we report that G-Rp1 inhibits lung cancer cell proliferation, migration and adhesion in p53 wild-type A549 and p53-defi cient H1299 cells. Anti-proliferative activity of G-Rp1 in lung cancer cells is mediated by enhanced nuclear localization of cyclin-dependent kinase inhibitors including $p27^{Kip1}$ and $p21^{WAF1/Cip1}$, and subsequent inhibition of pRb phosphorylation. We also show that these anti-tumor activities of G-Rp1 in both A549 and H1299 cells appear to be mediated by suppression of mitogenic signaling pathways such as ERK, Akt and $p70^{S6K}$. Taken together, these findings suggest further development and evaluation of G-Rp1 for the treatment of lung cancers with mutated p53 as well as wild-type p53.

• Biomolecules & Therapeutics
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• v.28 no.1
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• pp.1-17
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• 2020

Myeloid-derived suppressor cells (MDSCs) are immature myeloid cells that exert suppressive function on the immune response. MDSCs expand in tumor-bearing hosts or in the tumor microenvironment and suppress T cell responses via various mechanisms, whereas a reduction in their activities has been observed in autoimmune diseases or infections. It has been reported that the symptoms of various diseases, including malignant tumors, can be alleviated by targeting MDSCs. Moreover, MDSCs can contribute to patient resistance to therapy using immune checkpoint inhibitors. In line with these therapeutic approaches, diverse oligonucleotide-based molecules and small molecules have been evaluated for their therapeutic efficacy in several disease models via the modulation of MDSC activity. In the current review, MDSC-targeting oligonucleotides and small molecules are briefly summarized, and we highlight the immunomodulatory effects on MDSCs in a variety of disease models and the application of MDSC-targeting molecules for immuno-oncologic therapy.

• Journal of Life Science
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• v.22 no.9
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• pp.1224-1230
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• 2012

Cancer chemotherapy drugs command a large share of the market, and the development of new therapeutics with high efficacy and specificity is an active area of study. Recently, the development of cancer therapeutics from natural products targeting angiogenesis has drawn attention due to conventional chemotherapeutics showing serious side effects and resistance in cancer cells. In this study, we investigated the pharmacological efficacy of Gomisin A, an active ingredient of Schizandra chinensis baillon, on tumor growth and metastasis. Administration of Gomisin A at 10 and 100 ${\mu}g/ml$ reduced tumor growth in vivo by $80.5{\pm}8.1%$ and $96.2{\pm}2%$, respectively, compared with positive tumor controls. Treatment of Gomisin A in normal and various tumor cell lines did not exert significant toxicity. Mice treated with Gomisin A at a concentration of 10 and 100 ${\mu}g$/head showed a significant reduction in tumor-induced angiogenesis of $151{\pm}16.9%$ and $98.5{\pm}29.5%$, respectively. Furthermore, tumor metastasis analysis revealed that the administration of Gomisin A at a concentration of 10 and 100 ${\mu}g$/head inhibited tumor metastasis by $13.5{\pm}8.56%$ and $58.3{\pm}9.12%$, respectively. In addition, Gomisin A significantly decreased cell adhesion of the B16BL6 cells to the extracellular matrix. These results demonstrate that Gomisin A inhibits tumor growth via suppression of angiogenesis and tumor metastasis inhibition, without cellular toxicity. The pharmacological efficacy of Gomisin A suggests that it may be a potential candidate for the development of cancer drugs.

• BMB Reports
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• v.45 no.11
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• pp.659-664
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• 2012

Extracellular superoxide dismutase (EC-SOD) overexpression modulates cellular responses such as tumor cell suppression and is induced by $IFN{\gamma}$. Therefore, we examined the role of EC-SOD in $IFN{\gamma}$-mediated tumor cell suppression. We observed that the dominant-negative protein kinase C delta ($PKC{\delta}$) suppresses $IFN{\gamma}$-induced EC-SOD expression in both keratinocytes and melanoma cells. Our results also showed that $PKC{\delta}$-induced EC-SOD expression was reduced by pretreatment with a PKC-specific inhibitor or a siRNA against $PKC{\delta}$. $PKC{\delta}$-induced EC-SOD expression suppressed cell proliferations by the up-regulation of p21 and Rb, and the downregulation of cyclin A and D. Finally, we demonstrated that increased expression of EC-SOD drastically suppressed lung melanoma proliferation in an EC-SOD transgenic mouse via p21 expression. In summary, our findings suggest that $IFN{\gamma}$-induced EC-SOD expression occurs via activation of $PKC{\delta}$. Therefore, the upregulation of EC-SOD may be effective for prevention of various cancers, including melanoma, via cell cycle arrest.

• The Journal of Internal Korean Medicine
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• v.26 no.2
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• pp.310-319
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• 2005

Objectives: The aim is to identify any anti-tumor effects of Duchesnea indica(Andr.) Focke on colon cancer cells. Materials & Methods: Colo201 human adenocarcinoma cells were obtained from American Type Culture Collection. The boiled extract of Duchesnea indica(Andr.) Focke was added (10 and 20 microliters) to cultures and observed at 0, 6, and 12 hours, and at 12-hour intervals thereafter. Morphological changes in colon cancer cells were observed through an inverted microscope, Destruction of colon cancer cells was measured through Trypan blue exclusion testing. Suppression of the viability of colon cancer cells were measured via MTT assay. Anti-cancer mechanisms in the cell cycle of colon cancer cells were analysed via flow cytometry. Results: After introduction of Duchesnea indica(Andr.) Focke to cultures several changes were seen. Significant atrophy of the nucleus and cytoplasm of colon cancer cells was observed, indicating cell injury. Destruction of colon cancer cells was observed in direct proportion to dosage and duration. Suppression of viability of colon cancer cells for each test group was greater than that of the control group increasingly over time(36h, 48h, 60h, 72h), which was statistical significant (p<0.05). Cell numbers of the mitosis phase of the colon cancer cell cycle reduced. Conclusions: Statistcally significant anti-tumor effects of Duchesnea indica(Andr.) Focke were observed in this in vitro experiment. Results support a role for Duchesnea indica(Andr.) Focke in treatment of colon cancer. though it will required progressive research to develop a practical treatment.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.1
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• pp.239-244
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• 2014

Several recent studies have showed that the n-myc downstream regulated gene 2 (NDRG2) is a new tumor suppressor gene, and that it plays an important role in tumor suppression in several cancers or cancer cell lines. However, few studies focused on its function in neuroblastoma cells. In the present investigation, we demonstrated that NDRG2 overexpression inhibited their proliferation. Using a cDNA microarray, we found that overexpression of NDRG2 inhibited the expression of cysteine-rich protein 61 (CYR61), a proliferation related gene. From our research, CYR61 may partially hinder NDRG2-mediated inhibition of cell proliferation. Overexpression of NDRG2 resulted in accumulation of cells in the G1 phase, which was accompanied by upregulation of p21 and p27 and downregulation of CDK4 and cyclin D1. Taken together, these data indicate that NDRG2 inhibits the proliferation of neuroblastoma cells partially through suppression of CYR61. Our findings offer novel insights into the physiological roles of NDRG2 in neuroblastoma cell proliferation, and NDRG2 may prove to be effective candidate for the treatment of children with neuroblastoma.