• Korean Journal of Microbiology
• /
• v.42 no.4
• /
• pp.319-325
• /
• 2006

[ $\beta$ ]-Glucans (AG) were prepared from Agaricus blazei cultured in the medium fortified with the roots of Pueraria spp. by repeated extraction with hot water, gel filtration chromatography and DEAE ion exchange chromatography. Oligosaccharides (AO) were derived from the hydrolysis of AG by an endo-$\beta$-(1$\rightarrow$6)-glucanase from Bacillus megaterium. The anti-HT-29 human colon cancer activity of AG or AO was investigated using MTT assay, apoptosis assay, cell cycle analysis, and cDNA microairay. AG and AO both inhibited proliferation and growth of HT-29 cells, and stimulated apoptosis of the cells in a dose-dependent manner. In cell cycle analysis, treating HT-29 cells with AG or AO resulted in the increase of cells in the G0 (sub-G1) and G1 phase. Especially, AO was more effective in inducing G0/G1 cell cycle arrest than AG. To screen the genes involved in the increase of apoptosis, the gene expression profile of the HT-29 cells treated with AO was examined by cDNA microarray. While several genes involved in cell cycle progression (CCND2 and CDK2) were down-regulated, many genes involved in apoptosis (TNFSF9, TNFRSF9, FADD, CASP8, BAD, CRADD, CASP9 etc), cell cycle inhibitor (CDKN2A), immune response (IL6, IL18, IL6R etc), and tumor suppressor (CEACAM1, TP53BP2, IRF1, and PHB) were up-regulated. These results suggest that AO could inhibit the proliferation and growth of HT-29 cells by G0/G1 cell cycle arrest and induction of apoptosis.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.27 no.5
• /
• pp.373-384
• /
• 2001

Cellular proliferation is an intricately regulated process mediated by the coordinated interactions of critical growth control genes. Two of these factors in mammalian cells are the p53 and mdm-2 genes. A protein product of the mem-2 oncogene has been recently shown to associate with the protein encoded by the tumor suppressor gene p53. The p53 tumor suppressor protein is stabilized in response to DNA damage and other stress signals and causes the cell to undergo growth arrest or apoptosis, thus preventing the establishment of mutations in future cellular generations. Mutation or loss of p53 is a very common event in tumor progression. It occurs in about 50% of all tumors analysed including of colon, lung, breast and liver. The cellular mdm-2 gene, which has potential transforming activity that can be activated by overexpression, is amplified in a significant percentage of human sarcoma and in other mammalian tumors. Proteins encoded by the mdm-2 gene are able to bind to the p53 protein and, when overexpressed, can inhibit p53's transcriptional activation function, thus mdm-2 can act as a negative regulator of p53 function. Experimental study was performed to observe the relationship between p53 gene mutation and mdm-2 protein expression and apply the results to the clinical activity. 36 golden syrian hamster each weighing $60{\sim}80g$ were used and painted with 0.5% DMBA by 3 times weekly on the right buccal cheek(experimental side) for 6, 8, 10, 12, 14 and 16 weeks. Left buccal cheek(control side) was treated with mineral oil as the same manner to the right side. The hamsters were sacrificed on the 6, 8, 10, 12, 14 & 16 weeks. Normal and tumor tissues from paraffin block were examined for histology and immunohistochemistry observation, and were completely dissected by microdissection and DNA from both tissue were isolated by proteins K/phenol/chloroform extraction. Segments of the hamster p53 exons 5, 6, 7 and 8 were amplified by PCR using the oligonucleotide primers, and then confirmational change was observed by SSCP respectively. The results were as follows : 1. Dysplasia at 6 weeks, carcinoma in situ at 8 weeks and invasive carcinoma from 10 weeks could be observed in experimental groups. 2. p53 mutations were detected in 10 of the 36(28%) and the exons 6(6 of the 10 : 60%) was the most hot spot area among the highy conserved region(exons 5, 6, 7 & 8). 3. Immunohistochemical study confirmed 22 of the 36(61%) of p53 expression involving 10 of p53 mutations. 4. mdm-2 expression of was showed in 3 of the 36(8%) involving 1 of the 22 of p53 expression and 2 of the 14 of p53 non-expression. From the above results, mutation of p53 gene or expression of p53 protein may have the influence of the DMBA induced carcinoma of hamster buccal pouch but the expression of mdm-2 protein may not have relationship with tumorigenesis.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.11
• /
• pp.4671-4676
• /
• 2014

Background: MicroRNA-200a (miR-200a) has been reported to regulate tumour progression in several tumours but little is known about its role in neuroblastoma. Our aim was to investigate the potential role and mechanism of miR-200a in neuroblastomas. Materials and Methods: Expression levels of miR-200a in tissues were determined using RT-PCR. The effect of miR-200a and shAP-$2{\gamma}$ on cell viability was evaluated using MTS assays, and target protein expression was determined using Western blotting and RT-PCR. Luciferase reporter plasmids were constructed to confirm direct targeting. Results were reported as mean${\pm}$S.E.M and differences were tested for significance using the 2-tailed Students t-test. Results: We determined that miR-200a expression was significantly lower in neuroblastoma tumors than the adjacent non-cancer tissue. Over-expression of miR-200 are reduced cell viability in neuroblastoma cells and inhibited tumor growth in mouse xenografts. We identified AP-$2{\gamma}$ as a novel target for miR-200a in neuroblastoma cells. Thus miR-200a targets the 3'UTR of AP-$2{\gamma}$ and inhibits its mRNA and protein expression. Furthermore, our result showed that shRNA knockdown of AP-$2{\gamma}$ in neuroblastoma cells results in significant inhibit of cell proliferation and tumor growth in vitro, supporting an oncogenic role of AP-$2{\gamma}$ in neuroblastoma. Conclusions: Our study revealed that miR-200a is a candidate tumor suppressor in neuroblastoma, through direct targeting of AP-$2{\gamma}$. These findings re-enforce the proposal of AP-$2{\gamma}$ as a therapeutic target in neuroblastoma.

• Journal of Life Science
• /
• v.15 no.5 s.72
• /
• pp.726-733
• /
• 2005

Histone deacetylase (HDAC) inhibitors target key steps of tumor development. They inhibit proliferation, induce differentiation and/or apoptotic cell death, and exhibit potent antimetastatic and antiangiogenic properties in cancer cells in vitro and in vivo. Although they are emerging as a promising new treatment strategy in malignancy, how they exert their effect on human non-small cell lung cancer cells is as yet unclear. The present study was undertaken to investiate the underlying mechanism of a HDAC inhibitor trichostatin A (TSA)-induced growth arrest and its effect on the cell cycle control gene products in a human lung carcinoma cell line A549. TSA treaoent induced the growth inhibition and morphological changes in a concentration-dependent manner. Treatment of A549 cells with TSA resulted in a concentration-dependent increased G1 (under 100 ng/ml) and/or G2/M (200 ng/ml) cell population of the cell cycle as determined by flow cytometry Moreover, 200 ng/ml TSA treatment significantly induced the population of sub-G1 cells (23.0 fold of control). This anti-proliferative effect of TSA was accompanied by a marked inhibition of cyclins, positive regulators of cell cycle progression, and cyclin-dependent kinases (Cdks) expression and concomitant induction of tumor suppressor p53 and Cdk inhibitors such as p21 and p27 Although further studies are needed, these findings provide important insights into the possible molecular mechanisms of the anti-cancer activity of TSA in human lung carcinoma cells.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.27 no.6
• /
• pp.483-490
• /
• 2001

There were many controversies in the cause and progress of tumorigenesis. Recently, studies on the mutation of genes related to the tumor have extensively been performed due to development of molecular biology. Structural and morphological changes of chromosomes, which are related to the abnormal activation of oncogenes or inactivation of tumor suppression genes, transform the normal cells into the tumor cells. p53 and Rb are well known tumor suppressor genes, while oncogenes include c-myc, bcl-2 and ras, etc. When exposed to cell damaging agents, p53 inhibits cell growth by inducing transcription of p21. Especially p73, which is homo-logy of p53, frequently deleted in melanoma, neuroblastoma, colon cancer, and breast cancer, when over produced, p73 activates the transcription of p21, bax-1 and inhibits cell growth by inducing apoptosis. For study on mRNA expression of p21 and p73, normal oral keratinocytes, and cell lines of primary and metastatic oral squamous cell carcinoma were cultured and then electrophoresis and RT-PCR(reverse transcription-polymerase chain reaction) were performed. 1. The mRNA of p21 and p73 in normal oral keratinocyte expressed lower than that of primary squamous cell carcinoma. 2. The mRNA of p21 in metastatic oral squamous carcinoma cell lines was expressed as various patterns compared with that of normal oral keratinocyte. 3. In the metastatic oral squamous cell lines, the mRNA of HN8 expressed higher than that of HN12 or HN19. 4. The mRNA of p73 in primary oral squamous cell lines expressed 4-5 times higher than that of normal keratinocyte. 5. In metastatic oral squamous cell lines, there was no significant expression of p73 mRNA compared with that of normal oral keratinocyte. From the results obtained in this study, mRNA expression of p73 in primary oral squamous cell lines was remarkable, while mRNA expression of p21 and p73 in metastatic oral squamous cell lines were statistically insignificant.

• Applied Chemistry for Engineering
• /
• v.24 no.5
• /
• pp.525-529
• /
• 2013

Contents of the total polyphenols and flavonoids in the dietary fiber from tubers and stalks of domestic sweet potatoes were investigated. In addition, their antioxidant activity as well as the potent anti-cancer effects through the growth inhibition in human colon cancer cells (HT-29) in vitro were tested. The total flavonoids as naringin equivalents in dietary fiber from tubers and stalks of sweet potatoes were $0.5{\pm}0.001$ naringin/g extract and $2.0{\pm}0.008$ mg naringin/g extract dry basis, respectively. The amounts of the total polyphenols as gallic acid equivalents were $2.8{\pm}0.01$ mg gallic acid/g dry basis and $6.3{\pm}0.03$ mg gallic acid/g dry basis, respectively. 1,2-Diphenyi-1-picrylhydrazyl (DPPH) radical-scavenging activity of the dietary fiber from stalks was 2.4 times higher than that of the dietary fiber from tubers. Interestingly, a strong growth inhibition on HT-29 cells was observed in both dietary fibers originated from stalks and tubers of sweet potato in a dose-dependent manner. In addition, we found that the dietary fiber from tubers and stalks of sweet potato increased the gene expression of tumor suppressor p53. The great potential value in the prevention of various diseases including cancer the potential value could be confirmed through effects of the dietary fiber from tubers and stalks of sweet potato on antioxidant activity and anticancer in human colon cancer.

• Asian Pacific Journal of Cancer Prevention
• /
• v.13 no.12
• /
• pp.6299-6303
• /
• 2012

Insulin-like growth factor-binding protein-3 (IGFBP3) has been identified as a putative tumor suppressor with multifunctional roles in the IGF axis. Recently, there have been a growing body of studies investigating the relation between the IGFBP3 A-202C polymorphism, circulating IGFBP3 and prostate cancer risk, but their outcomes varied leading to controversy. Hence, it is necessary to perform a meta-analysis covering all eligible studies to shed a light on the association of IGFBP3 A-202C and cancer risk. Finally, we included a total of 11 relevant articles between 2003 and 2010 covering 14 case-control studies including 9,238 cases and 8,741 controls for our analysis. Our results showed that A-202C was a marginal risk factor of prostate cancer (allele contrast: OR=1.08, 95% CI :1.01-1.16; dominant model: OR=1.11, 95% CI :1.01-1.22; heterozygote codominant model: OR=1.11, 95% CI :1.03-1.18; homozygote contrast: OR=1.19, 95% CI :1.03-1.37). Stratification analysis revealed that sample size and control source were two major heterogeneous meta-factors especially in the recessive model (source: Population-based control group :p=0.30,I2=16.7%, Hospital-based control group: p=0.20, I2=30.3%; sample size: Small: p=0.22,I2= 32.8%, Medium: p=0.09,I2=48%, Large p=0.60,I2=0.0%); However, contrary to previous findings, no significance was found in racial subgroups. No significant publication bias was found in our analysis. Considering the robustness of the results and the discrepancy among some studies, there might be some unsolved confounding factors, and further more critical large studies are needed for confirmation.

• The Plant Pathology Journal
• /
• v.24 no.3
• /
• pp.296-304
• /
• 2008

The transient and rapid expression system of a foreign protein in planta is a very useful technique in biotechnology application. We have investigated optimum condition of Agrobacterium-infiltration technique in which expression level of foreign proteins were maximized without detrimental effects on plants using GFP and Cucumber mosaic virus 2b protein, which is known as an enhancer of gene expression and a suppressor of post-transcriptional gene silencing(PTGS). The optimum expression level of both RNA and protein of GFP with minimum leaf impairment was obtained at $OD_{600}$=0.2 of Agrobactrium inocula. The steady-state levels of GFP RNA and protein generally peaked at 3 and 7 days post-infiltration(dpi), respectively. In the presence of 2b, both the magnitude and duration of GFP expression was highly increased and we could detect GFP level until 17 dpi. On the other hands, the 2b-mediated higher accumulation of foreign proteins resulted in the repression of normal leaf growth, possibly due to the limitation of supply of energy or materials required for growth maintenance. Using this Agrobacterium-infiltration system with 2b and GFP, we tested a hypothesis for the threshold model of PTGS initiation. Four GFP transgenic lines of N. benthamiana, which shows different expression level of GFP were tested to determine the threshold level for PTGS initiation. Agrobacterium-infiltration of GFP into those GFP-transgenic plants resulted in the co-silencing of the transgenic GFP. It was found that very low concentration of Agrobacterium with GFP and GFP+2b($OD_{600}$=0.002-0.02) which could not phenotypically induce an additive GFP expression, was enough to trigger PTGS pathway in all GFP transgenic plants. This strongly indicates that each GFP-transgenic plant should be expressing the transgenic GFP at its own pre-determined level and there was no buffer zone of additive GFP-expression to the threshold. In other words, the PTGS seems to be immediately activated as a self-defensive mechanism if an internal balance of gene expression is broken.

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

• Journal of Life Science
• /
• v.18 no.3
• /
• pp.336-343
• /
• 2008

Histone deacetylases (HDACs) inhibitors have emerged as the accessory therapeutic agents for various human cancers, since they can block the activity of specific HDACs, restore the expression of some tumor suppressor genes and induce cell differentiation, cell cycle arrest and apoptosis in vitro and in vivo. In the present study, we investigated that the effect of trichostatin A (TSA), an HDAC inhibitor, on the cell growth and apoptosis, and its effect on the nuclear factor-kappaB $(NF-{\kappa}B)$ activity in 267B1 human prostate epithelial cells. Exposure of 267B1 cells to TSA resulted in growth inhibition and apoptosis induction in and dose-dependent manners as measured by fluorescence microscopy, agarose gel electrophoresis and flow cytometry analysis. TSA treatment inhibited the levels of IAP family members such as c-IAP-1 and c-IAP-2 and induced the proteolytic activation of caspase-3, -8 and -9, which were associated with concomitant degradation of poly (ADP-ribose)-polymerase, ${\beta}-catenin$ and laminin B proteins. The increase in apoptosis by TSA was connected with the translocation of $NF-{\kappa}B$ from cytosol to nucleus, increase of the DNA binding as well as promoter activity of $NF-{\kappa}B$, and degradation of cytosolic inhibitor of KappaB $(I{\kappa}B)-{\alpha}$ protein. We therefore concluded that TSA demonstrated anti-proliferative and apoptosis-inducing effects on 267B1 cells in vitro, and that the activation of caspases and $NF-{\kappa}B$ may play important roles in its mechanism of action. Although further studies are needed, these findings provided important insights into the possible molecular mechanisms of the anti-cancer activity of TSA.