• 약학회지
• /
• 제49권1호
• /
• pp.38-43
• /
• 2005

The occurrence of resistance to chemotherapeutic drugs is a major problem for successful cancer treatment. This resistant phenotype of cancer cell frequently reveals a broad spectrum to structurally and/or functionally unrelated anticancer drugs, termed multidrug resistance (MDR). Overexpression of P-glycoprotein (P-gp), a transmembrane drug efflux pump, is a major mechanism of MDR. Accordingly, considerable effort has been directed towards to development of compounds that inhibit P-gp, reverse the MDR phenotype and sensitize cancer cells to conventional chemotherapy without undesired toxicological effects. In an effort to search for novel MDR reversal agent, we tested the cytotoxicity of paclitaxel, a well-known substrate of P-gp, against P-gp-expressing HCT15 and HCT15/CL02 human colorectal cancer cells in the presence or absence of benzotriazepin analogues, as well as against P-gp-negative A549 human non-small cell lung and SK-OV-3 human ovarian cancer cells in vitro. Among the compounds tested, the agents that have phenyl amide moiety at 3 position remarkably increased the cytotoxicity of paclitaxel against P-gp-expressing cancer cells, but not against P-gp-negative cancer cells. BTZ-15 and BTZ-16 at $4\;{\mu}M$ revealed similar MDR reversal activity to $10\;{\mu}M$ verapamil, a well-known MDR reversal agent.

• Asian Pacific Journal of Cancer Prevention
• /
• 제13권9호
• /
• pp.4807-4814
• /
• 2012

Purpose: The chemoresistance of human hepatocellular carcinoma (HCC) to cytotoxic drugs, especially intrinsic or acquired multidrug resistance (MDR), still remains a major challenge in the management of HCC. In the present study, possible mechanisms involved in MDR of HCC were identified using a 5-fluorouracil (5-FU)-resistant human HCC cell line. Methods: BEL-7402/5-FU cells were established through continuous culturing parental BEL-7402 cells, imitating the pattern of chemotherapy clinically. Growth curves and chemosensitivity to cytotoxic drugs were determined by MTT assay. Doubling times, colony formation and adherence rates were calculated after cell counting. Morphological alteration, karyotype morphology, and untrastructure were assessed under optical and electron microscopes. The distribution in the cell cycle and drug efflux pump activity were measured by flow cytometry. Furthermore, expression of potential genes involved in MDR of BEL-7402/5-FU cells were detected by immunocytochemistry. Results: Compared to its parental cells, BEL-7402/5-FU cells had a prolonged doubling time, a lower mitotic index, colony efficiency and adhesive ability, and a decreased drug efflux pump activity. The resistant cells tended to grow in clusters and apparent changes of ultrastructures occurred. BEL-7402/5-FU cells presented with an increased proportion in S and G2/M phases with a concomitant decrease in G0/G1 phase. The MDR phenotype of BEL-7402/5-FU might be partly attributed to increased drug efflux pump activity via multidrug resistance protein 1 (MRP1), overexpression of thymidylate synthase (TS), resistance to apoptosis by augmentation of the Bcl-xl/Bax ratio, and intracellular adhesion medicated by E-cadherin (E-cad). P-glycoprotein (P-gp) might play a limited role in the MDR of BEL-7402/5-FU. Conclusion: Increased activity or expression of MRP1, Bcl-xl, TS, and E-cad appear to be involved in the MDR mechanism of BEL-7402/5-FU.

• 한국산학기술학회논문지
• /
• 제12권11호
• /
• pp.5012-5018
• /
• 2011

1965년부터 1995까지 결핵의 전국적인 조사에 의하면, 한국에서 결핵의 발생과 약제 내성율은 감소하였지만 다재약제내성율의 유행은 여전히 심각한 문제이다. 본 연구의 목적은 2001 년부터 2008까지 대전에 약제 내성율과 성향을 조사하였다. 총 581건의 약제감수성 검사가 수행 되었으며 이중 하나이상의 항결핵제의 약물에 내성이 있는 경우가 104건(17.9%)이였고 적어도 INH에 내성이 있는 경우가 68건 (11.7 %), RFP내성이 41건(7.1 %)이였다. 단일 약제 내성율은 37건 (6.4 %) 분리되었으며 이들 중 INH에서 18건 (3.1 %) RFP에서 5건(0.9 %)이 분리 되었다. 적어도 isoniazid와 refampin에 내성인 다제내성결핵은 35건(6.0 %)에서 발견되었다. 그리고 MDR - TB와 관련된 나이요인에 40-60 세 포함되었다. 폐결핵의 약제내성율, 특히 MDR - TB의 약제내성율은 공공의료분야보다 민간 병원의 초치료 환자에서 높게 나왔다. 초기 약제내성은 일반적이며 약제감수성 검사는 이전 결핵 치료를 받지 않은 폐결핵 환자에 대해 유용성이 있다. 내성의 확산과 증가를 줄이기 위해 MDR - TB의 조기 진단과 함께 향상된 제어프로그램이 필요하다. 다제내성율은 여전히 한국에서 문제이다. 독립적으로 혹은 공공의료분야와 공동으로 다제내성율을 감소하기 위한 노력이 필요하다.

• Archives of Pharmacal Research
• /
• 제29권10호
• /
• pp.866-873
• /
• 2006

When patients with cancers are treated with chemotherapeutic agents a long time, some of the cancer cells develop the multidrug resistance (MDR) phenotype. MDR cancer cells are characterized by the overexpression of multidrug resistance1 (MDR1) gene which encodes P-glycoprotein (Pgp), a surface protein of tumor cells that functions to produce an excessive efflux and thereby an insufficient intracellular concentration of chemotherapeutic agents. A variety of studies have sought potent MDR modulators to decrease MDR1 gene expression in cancer cells. Our previous study has shown that curcumin exhibits characteristics of a MDR modulator in KB-V1 multidrug-resistant cells. The aim of this study was to further investigate the effect of curcumin on MDR1 gene expression in patient leukemic cells. The leukemic cells were collected from 78 childhood leukemia patients admitted at Maharaj Nakorn Chiang Mai Hospital, Chiang Mai, Thailand, in the period from July 2003 to February 2005. There were 61 cases of acute lymphoblastic leukemia (ALL), 14 cases of acute myeloblastic leukemia (AML), and 3 cases of chronic myelocytic leukemia (CML). There were 47 males and 31 females ranging from 1 to 15 years old. Bone marrows were collected. The leukemic cells were separated and cultured in the presence or absence of $10{\mu}M$ curcumin for 48 hours. MDR1 mRNA levels were determined by RT-PCR. It was found that curcumin reduced MDR1 gene expression in the cells from 33 patients (42%). Curcumin affected the MDR1 gene expression in 5 of 11 relapsed cases (45%), 10 of 26 cases of drug maintenance (38%), 7 of 18 cases of completed treatment (39%), and 11 of 23 cases of new patients (48%). The expression levels of MDR1 gene in leukemic patient cells as compared to that of KB-V1 cells were classified as low level (1-20%) in 5 of 20 cases (25%), medium level (21-60%) in 14 of 32 cases (44%), and high level (61-100%) in 14 of 20 cases (70%). In summary, curcumin decreased MDR1 mRNA level in patient leukemic cells, especially in high level of MDR1 gene groups. Thus, curcumin treatment may provide a lead for clinical treatment of leukemia patients in the future.

• Asian Pacific Journal of Cancer Prevention
• /
• 제17권1호
• /
• pp.51-55
• /
• 2016

Phytochemical investigation of Pistacia integerrima has highlighted isolation of two known compounds naringenin (1) and dihydrokaempferol (2). A crude extract and these isolated compounds were here evaluated for their effects on reversion of multidrug resistance (MDR) mediated by P-glycoprotein (P-gp). The multidrug resistance P-glycoprotein is a target for chemotherapeutic drugs from cancer cells. In the present study rhodamine-123 exclusion screening test on human mdr1 gene transfected mouse gene transfected L5178 and L5178Y mouse T-cell lymphoma cells showed excellent MDR reversing effects in a dose dependent manner. In-silico molecular docking investigations demonstrated a common binding site for Rhodamine123, and compounds naringenin and dihydrokaempferol. Our results showed that the relative docking energies estimated by docking softwares were in satisfactory correlation with the experimental activities. Preliminary interaction profile of P-gp docked complexes were also analysed in order to understand the nature of binding modes of these compounds. Our computational investigation suggested that the compounds interactions with the hydrophobic pocket of P-gp are mainly related to the inhibitory activity. Moreover this study s a platform for the discovery of novel natural compounds from herbal origin, as inhibitor molecules against the P-glycoprotein for the treatment of cancer.

• Biomolecules & Therapeutics
• /
• 제19권2호
• /
• pp.174-180
• /
• 2011

Experiments were carried out to determine the role of Raf-1 kinase in the development of drug resistance to paclitaxel in v-H-ras transformed NIH 3T3 fibroblasts (Ras-NIH 3T3). We established a multidrug-resistant cell line (Ras-NIH 3T3/Mdr) from Ras-NIH 3T3 cells by stepwise increases in paclitaxel. Drug sensitivity assays indicated that the $IC_{50}$ value for drug-resistant Ras-NIH 3T3/Mdr cells was more than 1 ${\mu}M$ paclitaxel, 10- or more-fold higher than for the parental Ras-NIH 3T3 cells. Western blot and RT-PCR analysis showed that the drug efflux pump a P-glycoprotein were highly expressed in Ras-NIH 3T3/Mdr cells, while not being detectable in Ras-NIH 3T3 cells. Additionally, verapamil, which appears to inhibit drug efflux by acting as a substrate for P-glycoprotein, completely reversed resistance to paclitaxel in Ras-NIH 3T3/Mdr cell line, indicating that resistance to paclitaxel is associated with overexpression of the multidrug resistance gene. Interestingly, Ras-NIH 3T3/Mdr cells have higher basal Raf-1 activity compared to Ras-NIH 3T3 cells. Unexpectedly, however, the colocalization of Raf-1 and its negative regulator Spry2 was less observed in cytoplasm of Ras-NIH 3T3/Mdr cells due to translocation of Spry2 around the nucleus in the perinuclear zone, implying that Raf-1 may be released from negative feedback inhibition by interacting with Spry2. We also showed that shRNA-mediated knockdown of Raf-1 caused a moderate increase in cell susceptibility to paclitaxel. Thus, the results presented here suggest that a Raf-1-dependent pathway plays an important role in the development of acquired drug-resistance.

• 대한임상검사과학회지
• /
• 제50권2호
• /
• pp.100-109
• /
• 2018

다제내성(multidrug-resistant, MDR) Acinetobacter baumannii 균주의 출현 및 확산이 전 세계적으로 보고되어 왔는데, 이들 대부분은 생물막 형성능력을 가지고 있다. 생물막 형성은 소독 및 건조에 대해 세균이 저항할 수 있도록 해주는 중요한 병독성 인자이다. 본 연구에서는 생물막을 형성하는 A. baumannii 임상 분리주를 대상으로 항균제 내성 기전에 대한 유전적 기초를 조사하였다. 크리스탈 바이올렛 분석법을 통해 생물막 형성능력을 확인한 결과 46균주가 생물막을 형성하는 것으로 나타났다. 이어서 REP-PCR을 수행하여 서로 다른 클론에 속하는 16 균주를 선택한 후 이 균주들을 대상으로 항균제 내성 인자를 검출하였다. 본 연구에서 분리된 9개 non-MDR (0.96) 균주와 7개의 MDR (1.05) 균주의 평균 생물량은 서로 달랐지만, 이 차이는 유의하지 않았다. 대부분의 생물막 형성 MDR 균주는 다양한 항균제 내성인자 ($bla_{OXA-23}$, armA 및 gyrA 및 parC의 돌연변이)를 가지고 있는 것으로 나타났다. 그러나 대부분의 non-MDR 균주는 항균제 내성인자를 포함하지 않는 것으로 나타났다. 우리의 결과는 A. baumannii 균주의 생물막 형성능력이 항균제 감수성과 상관관계가 적음을 시사한다. 또한 MDR A. baumannii 임상 분리주의 출현은 대개 항균제 내성과 관련된 유전자의 돌연변이나 또는 다양한 항균제 내성인자의 획득에 의한 것으로 사료된다.

• Biomolecules & Therapeutics
• /
• 제5권3호
• /
• pp.265-271
• /
• 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.

• Tuberculosis and Respiratory Diseases
• /
• 제66권3호
• /
• pp.198-204
• /
• 2009

연구배경: 다제내성결핵 치료에서 감수성으로 증명된 1차 항결핵제는 가장 항결핵효과가 큰 약제로 알려져 있다. 본 연구는 다제내성결핵 환자에서 표준 1차 항결핵제사용 후 1차 항결핵제에 대한 추가 내성 획득의 빈도와 그 위험 인자를 알아보고자 시행되었다. 방 법: 2004년 1월에서 2008년 5월까지 국립마산결핵병원에서 약제감수성 검사가 보고되기 전 표준 1차 항결핵제로 치료받은 다제내성결핵 환자 중에서 1차 항결핵제 치료 전과 1차 항결핵제 치료 후의 연속된 두 시점의 약제 감수성 검사 결과가 모두 있는 환자를 대상으로 하여 의무기록을 후향적으로 검토하였다. 결 과: 표준 1차 항결핵제로 치료 받은 41명 중 14명 (34.1%)에서 ethambutol (EMB) 혹은 pyrazinamide (PZA)에 대한 추가 내성이 획득되었다. 치료 전 isoniazid (INH), rifampicin (RFP)에만 내성을 보였던 11명 중 3명(27.3%)에선 EMB와 PZA에 동시 내성, 3명(27.3%)에선 PZA에 추가 내성이 획득되었다. INH, RFP, EMB에 내성을 보인 18명 중 6명(33.3%)에서 PZA에, INH, RFP, PZA에 내성을 보인 6명 중 2명(33.3%)에서 EMB에 추가 내성이 획득되었다. 대상 환자 중 10명(24.4%)에서 1차 항결핵제 치료 전 내성이었던 약제가 치료 후 감수성으로 전환되었다. 추가 내성획득과 연관된 통계학적으로 유의한 위험인자를 발견할 수 없었다. 결 론: 우리나라의 다제내성결핵 치료에서 1차 항결핵제는 추가 획득 내성의 위험을 고려하여 주의 깊게 사용해야 할 것으로 사료된다.

• Asian Pacific Journal of Cancer Prevention
• /
• 제15권16호
• /
• pp.6849-6853
• /
• 2014

Multidrug resistance (MDR) is a major impediment to successful chemotherapy of gastric cancer. Our aim was to establish an epirubicin-resistant cell subline (AGS/EPI) and to elucidate the mechanisms involved in acquired EPI resistance. The AGS/EPI cell subline developed by exposing parental AGS cells to stepwise increasing concentrations of EPI demonstrated 2.52-fold resistance relative to the AGS cell line, and mRNA expression of the ATP-dependent drug-efflux pump P-glycoprotein (Pgp), more recently known as ABCB1 protein, was similarly upregulated. An AGS/EPI cell subline could thus be effectively established, and MDR mechanism of these cells was shown to be related to the overexpression of mRNA of the ABCB1 gene.