• The Journal of the Korean dental association
• /
• v.37 no.7 s.362
• /
• pp.517-529
• /
• 1999

본 연구는 태령 19일된 백서 태자 두 개관에서 분리한 골모세포유사세포에 화학발암물질인 7,12-Dimethylbenz(a)anthracene (DMBA: 0.5 ㎍/ml) 및 tumor promotor인 12-O-tetradecanoyl-phorbol-13-acetate (TPA; 1.0 ㎍/ml)를 단독 혹은 복합 처리하여 PTRCC-DMBA, RCC-DMBA 및 RCC-DMBA-TPA 세포주를 확립시키고, 각 세포의 세포형태, 세포성장곡선, alkaline phosphatase와 acid phosphatase 활성 및 in vitro tumorigenicity를 연구하였다. 또한 c-myc, c-랜, c-jun, p53 및 Rb 유전자의 발현변화와 항암단백질인 p53 및 pRb 단백질의 발현변화를 관찰하여 골모세포유사세포가 악성형질전환되는 분자기전의 일단을 연구하고자 시행하였다. 본 실험에 사용한 모든 세포군에서 높은 aikaline phosphatase 활성과 낮은 acid phosphatase/alkaline phosphatase ratio를 보여 골모세포의 특성을 나타내었다. RCC-DMBA와 RCC-DMBA-TPA 세포는 정상세포나 PTRCC-DMBA에 비해 빠른 성장속도를 보였으며, 또한 SOFT AGAR상에서 colony를 형성하여 anchorage-independent growth를 나타내었다. 화학발암 물질로 악성변형된 세포들은 정상세포나 PTRCC-DMBA 세포에 비해 c-myc 유전자의 과발현이 관찰되었다. 정상세포에서 p53 유전자의 발현은 1.9 kb의 message만이 발현되었다. 그러나 화학발암물질로 형질전환된 세포에서는 1.9 kb message외에도 1.6 kb의 message가 더 발현되었으며, message의 양도 현저히 증가되었다. p53 단백질의 발현은 RCC-DMBA-TPA 세포에서 정상세포에 비해 현저히 감소하였으나, RCC-DMBA 세포에서는 유사한 경향을 보였다. Rb 유전자의 발현은 RCC-DMBA-TPA 세포에서만 현저히 감소하였으나, Rb 단백질의 발현은 정상세포에 비해 형질전환된 세포들에서 모두 현저히 감소되었고, 특히 RCC-DMBA-TPA 세포에서는 거의 발현되지 않았다. 이상의 결과에서 백서 태자 두 개관에서 분리한 골모세포유사세포는 화학발암물질인 DMBA에 의해 악성형질전환이 유도되었으며, c-myc의 과발현 및 p53과 Rb 단백질의 발현감소가 정상 골모세포유사세포의 악성변형과정에 밀접히 연관되어 있음을 시사한다.

• Molecules and Cells
• /
• v.43 no.5
• /
• pp.459-468
• /
• 2020

Nuclear receptor subfamily group H member 4 (NR1H4), also known as farnesoid X receptor, has been implicated in several cellular processes in the liver and intestine. Preclinical and clinical studies have suggested a role of NR1H4 in colon cancer development; however, how NR1H4 regulates colon cancer cell growth and survival remains unclear. We generated NR1H4 knockout (KO) colon cancer cells using clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein-9 nuclease (CAS9) technology and explored the effects of NR1H4 KO in colon cancer cell proliferation, survival, and apoptosis. Interestingly, NR1H4 KO cells showed impaired cell proliferation, reduced colony formation, and increased apoptotic cell death compared to control colon cancer cells. We identified MYC as an important mediator of the signaling pathway alterations induced by NR1H4 KO. NR1H4 silencing in colon cancer cells resulted in reduced MYC protein levels, while NR1H4 activation using an NR1H4 ligand, chenodeoxycholic acid, resulted in time- and dose-dependent MYC induction. Moreover, NR1H4 KO enhanced the anti-cancer effects of doxorubicin and cisplatin, supporting the role of MYC in the enhanced apoptosis observed in NR1H4 KO cells. Taken together, our findings suggest that modulating NR1H4 activity in colon cancer cells might be a promising alternative approach to treat cancer using MYC-targeting agents.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.4
• /
• pp.1025-1028
• /
• 2010

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.16
• /
• pp.7061-7069
• /
• 2015

Background: During the past decades, the incidence and mortality rate of stomach cancer has demonstrated a great decrease in the world, but it is still one of the most common and fatal cancers especially among men worldwide, including Iran. The MYC proto-oncogene, which is located at 8q24.1, regulates 15% of genes and is activated in 20% of all human tumors. MYC amplification and overexpression of its protein product has been reported in 15-30% of gastric neoplasias. The aim of this investigation was to find the relative efficacy of CISH (chromogenic in situ hybridization) or IHC (immunohistochemistry) in diagnosis and prognosis of gastric cancer, as well as the relationship of amplification and expression of C-MYC gene with patient survival. Materials and Methods: In this cross-sectional study, 102 samples of gastric cancer were collected from patients who had undergone primary surgical resection at the Cancer Institute Hospital, Tehran University of Medical Sciences, from July 2009 to March 2014. All samples were randomly selected from those who were diagnosed with gastric adenocarcinomas. CISH and IHC methods were performed on all of them. Results: Patients were classified into two groups. The first consisted of stage I and II cases, and the second of stage III and IV. Survival tests for both groups was carried out with referrnce to CISH test reults. Group II (stage III & IV) with CISH+ featured lower survival than those with CISH- (p=0.233), but group I (stage I & II) patients demonstrated no significant variation with CISH+ or CISH- (p=0.630). Kaplan-Meier for both groups was carried out with IHC test findings and showed similar results. This data revealed that both diffuse and intestinal types of gastric cancer occurred significantly more in men than women. Our data also showed that CISH+ patients (43%) were more frequent in comparison with IHC+ patients (14.7%). Conclusions: For planning treatment of gastric cancer patients, by focusing on expanding tumors, which is the greatest concern of the surgeons and patients, CISH is a better and more feasible test than IHC, in regard to sensitivity and specificity. Therefore, CISH can be used as a feasible test for tumor growth and prognosis in stage III and IV lesions. This study also indicated that C-MYC amplification in gastric cancer is correlated with survival in advanced stages.

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.13
• /
• pp.5181-5185
• /
• 2015

Background: CCAT1 has been reported to be linked with pathogenesis of malignancies including colon cancer and gastric cancer. However, the regulatory effect of CCAT1 in hepatocellular carcinoma (HCC) remains unclear. The purpose of this research was to identify any role of CCAT1 in the progression of HCC. Materials and Methods: Real time-PCR was performed to test the relative expression of CCAT1 in HCC tissues. A computation screen of CCAT1 promoter was conducted to search for transcription-factor-binding sites. The association of c-Myc with CCAT1 promoter in vivo was tested by Pearson correlation analysis and chromatin immunoprecipitation assay. Additionally, Kaplan-Meier analysis and Cox proportional hazards analyses were performed. Results: c-Myc directly binds to the E-box element in the promoter region of CCAT, and when ectopically expressed increases promoter activity and expression of CCAT1. Moreover, Kaplan-Meier analysis demonstrated that the patients with low expression of CCAT1 demonstrated better overall and relapse-free survival compared with the high expression group. Cox proportional hazards analyses showed that CCAT1 expression was an independent prognostic factor for HCC patients. Conclusions: The findings demonstrated CCAT1, acting as a potential biomarker in predicting the prognosis of HCC, is regulated by c-Myc.

• Toxicological Research
• /
• v.20 no.4
• /
• pp.307-313
• /
• 2004

The present study was undertaken to investigate the effects of mistletoe (Viscum album var. coloratum) growing on Carpinus laxiflora BL. on proliferation and differentiation of HL-60 acute promyelocytic leukemia cells. Aqueous extract and its $(NH_2)_2SO_4$ saturated fractions of the mistletoe exhibited potent anti-proliferation activity against HL-60 cells. Moreover, when HL-60 cells were treated with 0~30% and 30～70% $(NH_2)_2SO_4$ saturated fractions of the mistletoe, HL-60 expressed CD 66b or CD 14 cell surface antigens and showed activity to reduce nitroblue tetrazolium, indicating that mistletoe induces the differentiation of HL-60 into granulocytes or monocytes. To understand how mistletoe induces the differentiation, we investigated the expression of molecules for modulating the proliferation and differentiation of leukemia cells, such as c-Myc and myeloblastin. The 0~30% $(NH_2)_2SO_4$ saturated fraction of the mistletoe reduced the mRNA levels of c-Myc and myeloblastin in a time-dependent manner. The results indicate that the mistletoe induces the differentiation of HL-60 cells via the decrease of c-Myc and myeloblastin expressions. Thus, it is suggested that mistletoe has a therapeutic potential for the treatment of acute promyelocytic leukemia.

• Korean Journal of Microbiology
• /
• v.55 no.3
• /
• pp.199-205
• /
• 2019

Yeast two-hybrid (Y2H) technique has been used to study protein-protein interactions, but its application particularly to a large-scale analysis of protein interaction networks, is limited by the fact that the technique is labor-intensive, based on scoring colonies on plate. Here, we develop a new reporter for the measurement of the protein-protein interactions by flow cytometry. The yeast harboring interacting proteins can also be enriched by fluorescence-activated cell sorting (FACS) or magnetic-activated cell sorting (MACS). When two interacting proteins are present in the same yeast cell, a reporter protein containing 10 tandem repeats of c-myc epitope becomes localized on the surface of the cell wall, without affecting cell growth. We successful measured the surface display of c-myc epitope upon interacting p53 with SV40 T antigen by flow cytometry. Thus, the newly developed Y2H assay based on the display of c-myc repeat on yeast cell wall could be used to the simultaneous analysis of multiple protein-protein interactions without laborious counting colonies on plate.

• Journal of Microbiology
• /
• v.39 no.4
• /
• pp.293-299
• /
• 2001

The nucleocapsid(NP) protein of Newcastle disease virus (NDV) and its derivative (NP$\sub$cfus)containing the myc region and six histidine residues fused to its C-terminus were pcpressed aboundantly in Escherichia coli. The proteins were purified by sucrose gradient centrifugation. Both the NP and NP$\sub$cfus/ proteins self-assem- bled into ring-like particles stacked together to from nucleocapsid-like structure which are heterogeneous in length with a diameter of 20${\pm}$2 nm and central holow of 5${\pm}$1 nm. Only a very small amount of the monomers in the particles was linked by inter-molecular disulfide bonds. Fusion of the C-terminal end to 29 amino acids inclusive of the myc epitope and His tag did not impair ring assembly buy inhibited the formation of the long herringbone structures. Immunogold lableing of the particles with the anti-myc antibody showed that the C-terminus of the NP$\sub$cfus/ protein is exposed on the surface of these ring-like particles.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.11
• /
• pp.6363-6367
• /
• 2013

Atractylis lancea (Thunb.) DC. (AL), an important medicinal herb in Asia, has been shown to have anti-tumor effects on cancer cells, but the involved mechanisms are poorly understood. This study focused on potential effects and molecular mechanisms of AL on the proliferation of the Hep-G2 liver cancer cell line in vitro. Cell viability was assessed by MTT test in Hep-G2 cells incubated with an ethanol extract of AL. Then, the effects of AL on apoptosis and cell cycle progression were determined by flow cytometry. Telomeric repeat amplification protocol (TRAP) assays was performed to investigate telomerase activity. The mRNA and protein expression of human telomerase reverse transcriptase (hTERT) and c-myc were determined by real-time RT-PCR and Western blotting. Our results show that AL effectively inhibits proliferation in Hep-G2 cells in a concentrationand time-dependent manner. When Hep-G2 cells were treated with AL after 48h,the $IC_{50}$ was about 72.1 ${\mu}g/mL$. Apoptosis was induced by AL via arresting the cells in the G1 phase. Furthermore, AL effectively reduced telomerase activity through inhibition of mRNA and protein expression of hTERT and c-myc. Hence, these data demonstrate that AL exerts anti-proliferative effects in Hep-G2 cells via down-regulation of the c-myc/hTERT/telomerase pathway.

• Toxicological Research
• /
• v.27 no.4
• /
• pp.253-259
• /
• 2011

Transforming growth factor ${\beta}$ (TGF-${\beta}$) is involved in cellular processes including growth, differentiation, apoptosis, migration, and homeostasis. Generally, TGF-${\beta}$ is the inhibitor of cell cycle progression and plays a role in enhancing the antagonistic effects of many growth factors. Unlike the antiproliferative effect of TGF-${\beta}$, E2, an endogeneous estrogen, is stimulating cell proliferation in the estrogen-dependent organs, which are mediated via the estrogen receptors, $ER{\alpha}$ and $ER{\beta}$, and may be considered as a critical risk factor in tumorigenesis of hormone-responsive cancers. Previous researches reported the cross-talk between estrogen/$ER{\alpha}$ and TGF-${\beta}$ pathway. Especially, based on the E2-mediated inhibition of TGF-${\beta}$ signaling, we examined the inhibition effect of 4-tert-octylphenol (OP) and 4-nonylphenol (NP), which are well known xenoestrogens in endocrine disrupting chemicals (EDCs), on TGF-${\beta}$ signaling via semi-quantitative reverse-transcription PCR. The treatment of E2, OP, or NP resulted in the downregulation of TGF-${\beta}$ receptor2 (TGF-${\beta}$ R2) in TGF-${\beta}$ signaling pathway. However, the expression level of TGF-${\beta}1$ and TGF-${\beta}$ receptor1 (TGF-${\beta}$ R1) genes was not altered. On the other hand, E2, OP, or NP upregulated the expression of a cell-cycle regulating gene, c-myc, which is a oncogene and a downstream target gene of TGF-${\beta}$ signaling pathway. As a result of downregulation of TGF-${\beta}$ R2 and the upregulation of c-myc, E2, OP, or NP increased cell proliferation of BG-1 ovarian cancer cells. Taken together, these results suggest that E2 and these two EDCs may mediate cancer cell proliferation by inhibiting TGF-${\beta}$ signaling via the downregulation of TGF-${\beta}$ R2 and the upregulation of c-myc oncogene. In addition, it can be inferred that these EDCs have the possibility of tumorigenesis in estrogen-responsive organs by certainly representing estrogenic effect in inhibiting TGF-${\beta}$ signaling.