• Archives of Pharmacal Research
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• v.29 no.11
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• pp.1018-1023
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• 2006

Chemoresistance remains the major obstacle to successful therapy of cancer. In order to understand the mechanism of multidrug resistance (MDR) that is frequently observed in lung cancer patients, here we studied the contribution of MDR-related proteins by establishing lung cancer cell lines with acquired resistance against etoposide. We found that human H460 lung cancer cells responded to etoposide more sensitively than A549 cells. Among MDR-related proteins, the expression of p-glycoprotein (Pgp) and lung resistance protein (LRP) were much higher in A549 cells compared with that in H460 cells. When we established H460-R1 and -R2 cell lines by progressive exposure of H460 cells to increasing doses of etoposide, the response against etopbside as well as doxorubicin was greatly reduced in R1 and R2 cells, suggesting MDR induction. Induction of MDR was not accompanied by a decrease in the intracellular accumulation of etoposide and the expression of MDR-related proteins that function as drug efflux pumps such as Pgp and MRP1 was not changed. We found that the acquired resistance paralleled an increased expression of LRP in H460 cells. Taken together, our data suggest the implicative role of LRP in mediating MDR in lung cancer.

• Journal of Microbiology and Biotechnology
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• v.17 no.11
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• pp.1856-1861
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• 2007

Physiological cell conditions such as glucose deprivation and hypoxia play roles in the development of drug resistance in solid tumors. These tumor-specific conditions cause decreased expression of DNA topoisomerase $II{\alpha}$, rendering cells resistant to topo II target drugs such as etoposide. Thus, targeting tumor-specific conditions such as a low glucose environment may be a novel strategy in the development of anticancer drugs. On this basis, we established a novel screening program for anticancer agents with preferential cytotoxic activity in cancer cells under glucose-deprived conditions. We recently isolated an active compound, AA-98, from Streptomyces sp. AA030098 that can prevent stress-induced etoposide resistance in vitro. Furthermore, LC-MS and various NMR spectroscopic methods identified AA-98 as mithramycin, which belongs to the aureolic acid group of antitumor compounds. We found that mithramycin prevents the etoposide resistance that is induced by glucose deprivation. The etoposide-chemosensitive action of mithramycin was just dependent on strict low glucose conditions, and resulted in the selective cell death of etoposide-resistant HT-29 human colon cancer cells.

• Journal of Microbiology and Biotechnology
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• v.29 no.4
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• pp.571-576
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• 2019

Microenvironmental stress, which is naturally observed in solid tumors, has been implicated in anticancer drug resistance. This tumor-specific stress causes the degradation of topoisomerase $II{\alpha}$, rendering cells resistant to topoisomerase $II{\alpha}$-targeted anticancer agents. In addition, microenvironmental stress can induce the overexpression of 78kDa glucose regulated protein (GRP78), which can subsequently block the activation of apoptosis induced by treatment with anticancer agents. Therefore, inhibition of topoisomerase $II{\alpha}$ degradation and reduction in GRP78 expression may be effective strategies for inhibiting anticancer drug resistance. In this study, we investigated the active compound arctigenin, which inhibited microenvironmental stress-induced etoposide resistance in HT-29 cells. Arctigenin was also highly toxic to etoposide-resistant HT-29 cells, with an $IC_{50}$ value of $10{\mu}M$ for colony formation. We further showed that arctigenin inhibited the degradation of topoisomerase $II{\alpha}$ and reduced the expression of GRP78. Thus, these results suggest that arctigenin is a novel therapeutic agent that inhibits resistance to etoposide associated with microenvironmental stress conditions.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7719-7724
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• 2013

Background: Overexpression of survivin, a known inhibitor of apoptosis, is associated with tumor progression and drug resistance in numerous malignancies, including leukemias. The aim of this study was to investigate the effect of a specific survivin small interference RNA (siRNA) on proliferation and the sensitivity of HL-60 acute myeloid leukemia (AML) cells to the chemotherapeutic drug etoposide. Materials and Methods: The cells were transfected with siRNAs using Lipofectamine $^{TM}2000$ transfection reagent. Relative survivin mRNA and protein levels were measured by quantitative real-time PCR and Western blotting, respectively. Trypan blue exclusion assays were performed to monitor tumor cell proliferation after siRNA transfection. The cytotoxic effects of etoposide and survivin siRNA, alone and in combination, on leukemic cells were determined using MTT assay. Apoptosis was assessed by ELISA cell death assay. Results: Survivin siRNA markedly reduced both mRNA and protein expression levels in a time-dependent manner, leading to distinct inhibition of cell proliferation and increased spontaneous apoptosis. Surprisingly, survivin siRNA synergistically increased the cell toxic effects of etoposide. Moreover, survivin down-regulation significantly enhanced its induction of apoptosis. Conclusions: Our study suggests that down-regulation of survivin by siRNA can trigger apoptosis and overcome drug resistance of leukemia cells. Therefore, survivin siRNA may be an effective adjuvant in AML chemotherapy.

• Journal of Yeungnam Medical Science
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• v.9 no.1
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• pp.75-89
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• 1992

The development of multi drug-resistant tumor cell population is a major problem in the chemotherapy of human cancer. These cells are often cross resistant to unrelated drugs and the precise mechanisms of multidrug resistant phenotype of tumor cells has not been fully elucidated. Cisplatin resistant tumor cell(SNU-1/$Cis_5$) was induced from human stomach cancer cell line(SNU-1) in vitro. Growth profiles of survival cells were observed during 5 days by thiazolyl blue (MTT) assay. To investigate the cross resistance of various anticancer drugs in SNU-1 and SNU-1/$Cis_5$, We compared the value of $IC_{50}$ - drug concentration at 50% survival of control and gained relative resistances (RR). The RR for SNU-1/$Cis_5$ were as follows; vinblastine, > 43.0 ; epirubicin, 22.9 ; dactinomycin, 16.0 ; etoposide, 15.0 ; vincristine, 9.2 ; adriamycin, 5.7 ; aclarubicin, 5.3. But 5-fluorouracil, methotrexate, daunorubicin have not cross resistance with cisplatin. Resistant inhibition values of $10{\mu}M$ verapamil for SNU-1/$Cis_5$ were as follows; vincristine, 13.1 ; epirubicin, 10.0 ; etoposide, 6.3 ; vinblastine, 4.4 ; dactinomycin, 3.6 ; daunorubicin, 2.4. Membrane proteins of 51,400 and 81,300 daltons were identified by radioiodination with SDS-PAGE, which might represented the drug resistance.

• Journal of Gynecologic Oncology
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• v.29 no.6
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• pp.89.1-89.8
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• 2018

Objective: Highly effective chemotherapy for patients with low-risk gestational trophoblastic neoplasia (GTN) is associated with almost a 100% cure rate. However, 20%-30% of patients treated with chemotherapy need to change their regimens due to severe adverse events (SAEs) or drug resistance. We examined the treatment outcomes of second-line chemotherapy for patients with low-risk GTN. Methods: Between 1980 and 2015, 281 patients with low-risk GTN were treated. Of these 281 patients, 178 patients were primarily treated with 5-day intramuscular methotrexate (MTX; n=114) or 5-day drip infusion etoposide (ETP; n=64). We examined the remission rates, the drug change rates, and the outcomes of second-line chemotherapy. Results: The primary remission rates and drug resistant rates of 5-day ETP were significantly higher (p<0.001) and significantly lower (p=0.002) than those of 5-day MTX, respectively. Forty-seven patients (26.4%) required a change in their chemotherapy regimen due to the SAEs (n=16) and drug resistance (n=31), respectively. Of these 47 patients failed the first-line regimen, 39 patients (39/47, 82.9%) were re-treated with single-agent chemotherapy, and 35 patients (35/39, 89.7%) achieved remission. Four patients failed second-line, single-agent chemotherapy and eight patients (17.0%) who failed first-line regimens were treated with combined or multi-agent chemotherapy and achieved remission. Conclusions: Patients with low-risk GTN were usually treated with single-agent chemotherapy, while 20%-30% patients had to change their chemotherapy regimen due to SAEs or drug resistance. The second-line regimens of single-agent chemotherapy were effective; however, there were several patients who needed multiple agents and combined chemotherapy to achieve remission.

• Tuberculosis and Respiratory Diseases
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• v.58 no.2
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• pp.135-141
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• 2005

배경 및 목적 : Multidrug Resistance-1 (MDR1) 유전자는 다약제내성에 관여하는 P-glycoprotein을 암호화한다. MDR1 유전자의 다형성은 P-glycoprotein의 발현과 기능의 차이를 일으켜 항암화학요법 반응에 영향을 미칠 수 있을 것이다. 저자들은 소세포폐암 환자에서 MDR1 유전자의 다형성과 일배체형에 따른 항암화학요법에 대한 반응을 조사하였다. 대상 및 방법 : 경북대학병원에서 병리적으로 소세포폐암으로 진단받고 etoposide-cisplatin 항암화학요법을 받은 54명을 대상으로 하였다. 전혈 5cc에서 DNA를 추출하고 PCR-RFLP법을 통해 MDR1 유전자 엑손 21의 2677G>T 다형성과, 엑손 26의 3435C>T 다형성을 조사하고 다형성과 일배체형에 따른 항암화학요법의 반응을 조사하였다. 결 과 : 2677G>T 유전자형에 따른 항암화학요법의 반응은 유의한 차이가 없었다. 3435 CC 유전자형은 3435 CT+TT 형에 비해 치료 반응율이 유의하게 높았다 (P = 0.025). 유전자형 분석 결과와 일치되게 2677G/3435C 일배체형은 다른 일배체형에 비해 치료반응을 보이는 경우가 유의하게 많았다 (P = 0.015). 결 론 : 소세포폐암에서 MDR1 유전자의 2677G>T와 3435C>T 다형성 및 이들 다형성의 일배체형은 etoposide-cisplatin 항암화학요법의 반응을 예측할 수 있는 지표로 사용될 수 있을 것으로 생각된다.

• Journal of Yeungnam Medical Science
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• v.6 no.2
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• pp.195-205
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• 1989

Development of drug resistance in tumors during treatment is a major factor limiting the clinical use of anticancer agents. When tumor cells acquire resistance to anticancer drug, they show cross-resistance to other antitumor agents. In the present study, SNU-1 cell was induced adriamycin $10^{-7}M$ drug resistance, SNU-1/ADR, in vitro culture system. We got the doubling time and number for viability test during 96 hours by MTT assay. To investigate the cross resistance of various anticancer drugs in human stomach cancer cell SNU-1 and SNU-1/ADR. We compared $IC_{50}$ (drug concentration of 50% reduction) and the relative resistance(RR). SNU-1/ADR was expressed multidrug resistant with vinblastine(RR ; 31.62), vincristine(RR ; 29.50), dactinomycin(RR ; 21.37), epirubicin(RR ; 17.78), daunorubicin(RR ; 14.12), adriamycin(RR ; 7.76), and etoposide(RR ; 4.46), and other drugs, 5-fluorouracil, cisplatin, cyclophosphamide, methotrexate, and aclarubicin, have not cross resistant with adriamycin. There was double minute chromosome in SNU-1/ADR by karyotyping although this change was not seen in SNU-1.

• Biomolecules & Therapeutics
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• v.5 no.3
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• pp.265-271
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• 1997

Since the advent of chemotherapy, certain types of cancer have been particularly resistant to chemotherapeutic treatment. One of the most well-studied types of resistance is resistance to multiple struc-turally dissimialr hydrophobic chemotherapeutic agents, or multidrug resistance (MDR). We found that MDR cells (KBV20C, KB7D) being highly resistant to colchicine, etoposide, and vincristine were found to have very low level of putrescine and low level of spermidine than the drug sensitive parental cells (KB) but they had almost same level of spermine as the drug sensitive cells. Although both MDR and drug sensitive cells had almost same rate of polyamine uptake, MDR cells were much more sensitive to an inhibitor of polyamine synthesis, methylglyoxal-bis guanylhydrazone (MGBG), suggesting that MDR cells might be defective in polyamine synthesis. These results also suggest that HGBG can be used for treatment of MDR in vivo.

• Archives of Pharmacal Research
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• v.19 no.5
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• pp.342-347
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• 1996

Doxorubicin, one of the clinically most useful anticancer agents, is used alone or in combination with other drugs against a wide variety of tumors, recently. But cancer cells developed resistance to this agent in many ways. This resistance is an important limiting factor of doxorubicin for anticancer drug. We newly established doxorubicin-resistant HCT15/CL02 subline from parental HCT15 human adenocarcinoma colon cancer cells. HCT15/CL02 revealed resistance to doxorubicin about 85-fold of its parental cells, and it also revealed cross-resistance to actinomycin D, etoposide and vinblastine but not to displatin and tamoxifen. And verapamil, a reversal agent of multidrug-resistance (MDR) by P-glycoprotein, elevated the cytotoxicity of doxorubicin against both HCT15 and GCT15/CL02 cells. But the relative resistant rate was not reduced. Verapamil had no effects on the tosicity of cisplatin to the both cell lines. These results indicate that HCT15/CL02 cells have some functionally complex mechanisms for MDR.