• 대한바이러스학회지
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• 제29권4호
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• pp.235-245
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• 1999

HIV-1 Tat, a strong transactivator, is essential for the HIV-1 replication and AIDS progression. The Tat function is markedly inhibited by human p53 anti-oncogene. However, the detail mechanism has not yet been clearly revealed. In our previous report, we have addressed that p53 is unlikely to interact directly with HIV-1 Tat. In the consecutive experiments, Tat-phosphorylation was found to increase in proportional to the amounts of transfected p53. This work was initiated to identify the signaling factor that is involved in the p53-mediated Tat suppression. Several protein kinases were tested for the phosphorylation of Tat, and we found that PKR is likely to be involved in the p53-mediated Tat suppression. PKR was co-immunoprecipitated by anti-Tat antibody in the Tat-expressing Jurkat cell lysates only when the cells were transfected by p53, indicating that PKR-Tat interaction depends on the p53 activity. The interaction seems to result in PKR-mediated Tat-phosphorylation. Tat function was not blocked by p53 when co-transfected trasiently with antisense-PKR. We have generated PKR-knock out Jurkat cell clone. The PKR defective Jurkat cells didn't show the p53-mediated Tat suppression. These data indicate that p53-mediated Tat suppression is strongly associated with PKR. PKR-mediated Tat phosphorylation experiments are now under investigation by kinase assay and co-immunoprecipitation in the presence or absence of p53.

• 대한한의학회지
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• 제20권1호
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• pp.91-105
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• 1999

The effects of Yinjin and Yinjinsaryongsangagambang on a DNA damaging agent, etoposide-induced apoptosis, cell viability, cell cycle progression, and mRNA expression of apoptosis-related genes of human hepatocyte cell line HepG2 were investigated using tryphan blue exclusion assay, MTT assay, flow cytometry, immunocytometric analysis of PCNA, and quantitative RT-PCR analysis. MTT assay showed that Yinjin and Yinjinsaryongsangagambang increases cellular viability of HepG2 cells in a dosage-dependent manner. Stimulation of cell cycle progression by Yinjin or Yinjinsaryongsangagambang was detected by flow cytometric analysis of the DNA content and immunocytometric analysis of PCNA expression. A significant reduction of a DNA-damaging agent, etoposide-induced apoptosis were found in both Yinjin and Yinjinsaryongsangagambang-treated cells in dosage-dependent manner. In overall, 3-fold reduction of apoptosis was recognized in $10.0\;{\mu}g/ml$ of Yinjin or Yinjinsaryongsangagambang-treated cells compared to untreated cells. Although the difference is not significant, Yinjinsaryongsangagambang showed slightly higher effect on the inhibition of apoptosis than Yinjin. From flow cytometric analysis of apoptosis, while 39.9% of untreated cells showed etoposide-induced apoptotic cell death, only 19.6% or 17.4% of Yinjin or Yinjinsaryongsangagambang-treated cells were fond at apoptotic sub G1 phase, respectively. Interestingly, strong induction of Gadd45-mRNA was observed from Yinjin or Yinjinsaryongsangagambang-treated cells. However, no changes in expression levels of p53 and Waf1 were detected, demonstrating that induction of Gadd45 mRNA expression by Yinjin or Yinjinsaryongsangagambang occurs by p53-independent mechanism. Marked mRNA inductions of two apoptosis-inhibiting genes, Bcl-2 and Bcl- XL, were found in both Yinjin or Yinjinsaryongsangagambang-treated HepG2 cells while no changes was detected in expression levels of an apoptosis-promoting gene, Bax.

• Asian Pacific Journal of Cancer Prevention
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• 제15권22호
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• pp.9655-9660
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• 2014

Background: Nigella Sativa (NS) is an herb from the Ranunculaceae family that exhibits numerous medicinal properties and has been used as important constituent of many complementary and alternative medicines (CAMs). The ability of NS to kill cancer cells such as PC3, HeLa and hepatoma cells is well established. However, our understanding of the mode of death caused by NS remains nebulous. The objective of this study was to gain further insight into the mode and mechanism of death caused by NS in breast cancer MCF-7 cells. Materials and Methods: Human breast cancer cells (MCF-7) were treated with a methanolic extract of NS, and a dose- and time-dependent study was performed. The $IC_{50}$ was calculated using a Cell Titer $Blue^{(R)}$ viability assay assay, and evidence for DNA fragmentation was obtained by fluorescence microscopy TUNEL assay. Gene expression was also profiled for a number of apoptosis-related genes (Caspase-3, -8, -9 and p53 genes) through qPCR. Results: The $IC_{50}$ of MCF-7 cells was $62.8{\mu}L/mL$. When MCF-7 cells were exposed to $50{\mu}L/mL$ and $100{\mu}L/mL$ NS for 24h, 48h and 72h, microscopic examination (TUNEL assay) revealed a dose- and time-dependent increase in apoptosis. Similarly, the expression of the Caspase-3, -8, -9 and p53 genes increased significantly according to the dose and time. Conclusions: NS induced apoptosis in MCF-7 cells through both the p53 and caspase pathways. NS could potentially represent an alternative source of medicine for breast cancer therapy.

• KSBB Journal
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• 제31권1호
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• pp.52-57
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• 2016

Mutant p53 (R280K) is highly expressed in MDA-MB-231 triple-negative human breast cancer cells. Currently, we reported the role of mutant p53-R280K in mediating the survival of MDA-MB-231 cells in vitro. The present study was undertaken to determine whether mutant p53-R280K affects breast cancer cell growth in vivo. To this end, we used small interfering RNA to knockdown the level of mutant p53-R280K in MDA-MB-231 cells. Silencing of mutant p53-R280K in MDA-MB-231 cells causes substantial tumor regression of established xenografts in vivo. In xenograft model for breast cancer, silencing of mutant p53-R280K in MDA-MB-231 cells significantly inhibited the tumor growth. Moreover, TUNEL assay showed more occurrence of apoptotic cells in mutant p53-R280K silenced tumors compared to control. Our data indicate that mutant p53-R280K has an important role in mediating tumor growth of MDA-MB-231 cells in vivo. Taken together, this study suggests that endogenous mutant p53-R280K could be used as a therapeutic target for breast cancer cells harboring this TP53 missense mutation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제42권6호
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• pp.337-344
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• 2016

Objectives: The purpose of this study was to evaluate the anti-cancer activity of cisplatin by studying its effects on cell viability and identifying the mechanisms underlying the induction of cell cycle arrest and apoptosis on oral squamous cell carcinoma (OSCC) cell lines with varying p53 mutation status. Materials and Methods: Three OSCC cell lines, YD-8 (p53 point mutation), YD-9 (p53 wild type), and YD-38 (p53 deletion) were used. To determine the cytotoxic effect of cisplatin, MTS assay was performed. The cell cycle alteration and apoptosis were analyzed using flow cytometry. Western blot analysis was used to detect the expression of cell cycle alteration- or apoptosis-related proteins as well as p53. Results: Cisplatin showed a time- and dose-dependent anti-proliferative effect in all cell lines. Cisplatin induced G2/M cell accumulation in the three cell lines after treatment with 0.5 and $1.0{\mu}g/mL$ of cisplatin for 48 hours. The proportion of annexin V-FITC-stained cells increased following treatment with cisplatin. The apoptotic proportion was lower in the YD-38 cell line than in the YD-9 or YD-8 cell lines. Also, immunoblotting analysis indicated that p53 and p21 were detected only in YD-8 and YD-9 cell lines after cisplatin treatment. Conclusion: In this study, cisplatin showed anti-cancer effects via G2/M phase arrest and apoptosis, with some difference among OSCC cell lines. The mutation status of p53 might have influenced the difference observed among cell lines. Further studies on p53 mutation status are needed to understand the biological behavior and characteristics of OSCCs and to establish appropriate treatment.

• 한국균학회지
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• 제28권1호
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• pp.55-59
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• 2000

까치버섯(Polyozellus multiplex) 메탄올 추출물과 물 추출물은 산화 유발물질인 $H_2O_2$에 대하여 메탄올 추출물과 물 추출물에서 각각 53.5%, 29.4%의 생존율을 보여 까치버섯 추출물의 항산화 효과를 확인하였다. 까치버섯 메탄올 추출물과 물 추출물을 이용하여 동물에 강력한 발암물질인 MHNG를 투여한 후 항산화 효소계를 측정한 결과, 물 추출물은 항산화효소인 glutathione S-transferase(GST)와 superoxide dismutase(SOD) 활성과 조직내의 해독물질인 glutathione(GSH)의 함량을 높여 주었다. 또한 0.5%의 까치버섯 물 추출물은 암억제 유전자인 p53회 발현을 매우 증가시켰다. 이상의 결과로 까치버섯(Polyozellus multiplex)은 항산화 능이 있으며 특히, 물 추출물은 체내의 항산화 효소를 활성화시키고 항산화 물질의 함량을 높여주었고 암 억제유전자인 p53의 발현을 증가시켜 항암효과가 있음을 보여주었다.

• 한국환경성돌연변이발암원학회지
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• 제21권2호
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• pp.128-134
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• 2001

Single cell gel electrophoresis (SCGE) assay, also called comet assay, is a rapid and sensitive method to detect DNA damage in single cell level. To evaluate the DNA damage of lymphocytes of pesticides sprayers, SCGE assay was carried out for 50 pesticides sprayer and 58 control subjects. They were interviewed with structured questionnaire to get the information about the kinds and amount of pesticide. Insecticides and fungicides were predominant among pesticides. Major components of pesticides were organophosphorus, organosulfate, cartap, carbamates, and triazole. Sprayed pesticides were classified into two groups. Group I included organophosphorus, organoarsenic, organotin, tetrazine, triazole and gramoxone, which were known to cause DNA damages. Group II pesticide were carbamates, surfactants, organosulfates, etc., which were not found as DNA damaging agents in scientific documents. Olive tail moments of 100 lymphocytes were measured by KOMET 3.1 program for each person. The means of tail moments were compared between farmers exposed to pesticides and control subjects. Farmers showed higher tail moments than control subjects (2.07$\pm$1.40 vs 1.53$\pm$0.77, p<0.05). The means of tail moments also were compared among group I sprayers (n=36), group II sprayers (n=24) and, control subject, and the means or tail moments were 3.4s$\pm$3.2o, 2.66$\pm$2.20 and 1.53$\pm$0.77 respectively. The difference between means of group I sprayers and controls was statistically significant (p<0.05). In conclusion, this study showed higher DNA damage in farmers exposed to pesticides than control subjects, and comet assay could be useful as a biological monitoring method of genotoxic pesticides for farmers.

• Animal cells and systems
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• 제4권2호
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• pp.181-186
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• 2000

The expression of $p21^{WAF1/ClP1/SDl1}$, one of the cyclin-dependent kinase inhibitors, is regulated by a variety of transcription factors including p53 and STAT. Heat shock induces the expression of p21 in a temperature- and time-dependent manner. Although the p21 induction by heat shock has been reported to be controlled by p53, a p53-independent mechanism Is also involved. To understand the p53-independent regulation of heat shock-induced p21 expression, we searched the promoter region of p21 gene and found one or two heat shock element (HSE)-like sequences in human, rat, and mouse. Electromobility shift assay (EMSA) showed that heat shock factor (HSF) could bind to these HSE-like sequences In response to heat shock, even though to a lesser extent than to HSE. In addition, p21 promoter deletion analysis revealed that heat shock activated a p21 deletion promoter construct containing the HSE-like sequences but lacking p53-binding sites, but not a promoter construct containing neither HSE-like sequences nor the p53-responsive element. Furthermore, the p21 induction by heat shook was significantly inhibited in confluent cells in which heat shock-induced HSF activation was reduced. These results suggest that the transcriptional regulation of p21 by heat shock may be mediated through activation and binding to HSE-like sequences of HSF.

• Asian Pacific Journal of Cancer Prevention
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• 제15권5호
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• pp.2313-2318
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• 2014

Peroxisome proliferator-activated receptor gamma (PPAR-${\gamma}$), a ligand-dependent nuclear transcription factor, has been found to widely exist in tumor tissues and plays an important role in affecting tumor cell growth. In this study, we investigated the effect of PPAR-${\gamma}$ on aspects of the cervical cancer malignant phenotype, such as cell proliferation and apoptosis. Cell growth assay, Western blotting, Annexin V and flow cytometry analysis consistently showed that treatment with troglitazone (TGZ, a PPAR-${\gamma}$ agonist) led to dose-dependent inhibition of cervical cancer cell growth through apoptosis, whereas T0070907 (another PPAR-${\gamma}$ antagonist) had no effect on Hela cell proliferation and apoptosis. Furthermore, we also detected the protein expression of p53, p21 and Mdm2 to explain the underlying mechanism of PPAR-${\gamma}$ on cellular apoptosis. Our work, finally, demonstrated the existence of the TGZ-PPAR-${\gamma}$-p53 signaling pathway to be a critical regulator of cell apoptosis. These results suggested that PPAR-${\gamma}$ may be a potential therapeutic target for cervical cancer.

• Asian Pacific Journal of Cancer Prevention
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• 제13권11호
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• pp.5887-5895
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• 2012

Background: To determine the effect of essential oil obtained from a traditionally used medicinal plant Tridax procumbens L, on lung metastasis developed by B16F-10 melanoma cells in C57BL/6 mice. Materials and Methods: Parameters studied were toxicity, lung tumor nodule count, histopathological features, tumor directed capillary vessel formation, apoptosis and expression levels of $P^{53}$ and caspase-3 proteins. Results: In vitro the MTT assay showed cytotoxicity was found to be high as 70.2% of cancer cell death within 24hrs for $50{\mu}g$. In vivo oil treatment significantly inhibited tumor nodule formation by 71.7% when compared with untreated mice. Formation of tumor directed new blood vessels was also found to be inhibited to about 39.5%. TUNEL assays also demonstrated a significant increase in the number of apoptotic positive cells after the treatment. $P^{53}$ and caspase-3 expression was also found to be greater in the essential oil treated group than the normal and cancer group. Conclusions: The present investigation showed significant effects of the essential oil of Tridax procumbens L in preventing lung metastasis by B16F-10 cell line in C57BL/6 mice. Its specific preventive effect on tumor directed angiogenesis and inducing effect on apoptosis warrant further studies at the molecular level to validate the significance of Tridax procumbens L for anticancer therapy.