• Asian Pacific Journal of Cancer Prevention
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• v.15 no.17
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• pp.7037-7041
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• 2014

Background: 5-Fluorouracil (5-FU) is the most commonly used drug in colon cancer therapy. However, despite impressive clinical responses initially, development of drug resistance to 5-Fu in human tumor cells is the primary cause of failure of chemotherapy. In this study, we established a 5-Fu-resistant human colon cancer cell line for comparative chemosensitivity studies. Materials and Methods: Real time PCR and Western blotting were used to determine gene expression levels. Cell viability was measured by MTT assay. Glucose uptake was assess using an Amplex Red Glucose/Glucose Oxidase assay kit. Results: We found that 5-Fu resistance was associated with the overexpression of Glut1 in colon cancer cells. 5-Fu treatment at low toxic concentration induced Glut1 expression. At the same time, upregulation of Glut1 was detected in 5-Fu resistant cells when compared with their parental cells. Importantly, inhibition of Glut1 by a specific inhibitor, WZB117, significantly increased the sensitivity of 5-Fu resistant cells to the drug. Conclusions: This study provides novel information for the future development of targeted therapies for the treatment of chemo-resistant colon cancer patients. In particular it demonstrated that Glut1 inhibitors such as WZB117 may be considered an additional treatment options for patients with 5-Fu resistant colon cancers.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.9
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• pp.4391-4394
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• 2016

Background: Platinum-based regimens are effective treatments for advanced non-small cell lung cancer (NSCLC), but the five-year survival rate is still less than 20%. One possible factor appears to be resistance involving polymorphisms in the CTR1 gene which plays an importance role in accumulation of platinum in the cytoplasm. Purpose: To establish both prevalence of CTR1 polymorphism and its impact on treatment related toxicity in Thai advanced NSCLC patients. Materials and Methods: Thirty-two advanced NSCLC participants received carboplatin and gemcitabine during January to June 2016 at King Chulalongkorn Memorial Hospital (KCMH) were recruited for analysis of the CTR1 rs12686377 genotype. These participants were planning to be treated with platinum-based chemotherapy for at least two cycles. Results: Allele frequency of CTR1 polymorphism $G{\rightarrow}T$ was found to be 25%. The results showed that genetic polymorphism at CTR1 rs12686377 was associated with emesis side effects (P = 0.020) and neuropathic symptoms (P = 0.010). In addition, hematologic side effects in terms of anemia also tended to be related to this polymorphism. Conclusions: This is the first study suggesting that polymorphism at CTR1 rs12686377 may be associated with toxicity from platinum-based regimens. Therefore, it could be a factor to aid in treatment decision-making.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.9
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• pp.5089-5093
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• 2013

Objective: This study aimed to investigate the effects of BCRP expression on tumor recurrence, metastasis and treatment tolerability. Methods: A VX2 rabbit liver tumor model was established. Division was randomly into 4 groups: namely saline control group; A group, given hydration lipiodol; B group, Ad-p53; and C group, Ad-p53+hydration lipiodol. After the intervention, samples were collected to detect the BCRP, MMP-2, VEGF and PCNA. Results: The expression of BCRP, MMP-2, PCNA and VEGF in tumors in Group A had no significant difference when compared with the control group, while in B and C group, the values were significantly lower (P<0.05). BCRP positive expression in metastatic lesions significantly increased (P<0.05), and was correlated with MMP-2 ($X^2=6.172$, P=0.0131). Conclusions: BCRP may play an important role in mediating liver cancer multidrug resistance to chemotherapy, and may be correlated with tumor recurrence and metastasis, which leads to weakened treatment effect. Ad-P53 can down-regulate the expression of related genes, playing a role in multidrug resistance reversal and increased sensitivity in liver cancer treatment.

• Microbiology and Biotechnology Letters
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• v.30 no.2
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• pp.157-161
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• 2002

Drug resistance is one of the most significant impediments to successful chemotherapy of cancer. Multidrug-resistance (MDR) is characterized by decreased cellular sensitivity to anticancer agents due to the overexpression of P-glycoprotein. By employing adriamycin-resistance CL02 cancer cells, we undertook the screening for agents which were effective to multidrug-resistant cancer cells. As a result, a myxobacterial strain JW117 was selected for study since the solvent extract of cell mass of the strain was found to exhibit significant activity against the CL02 cancer cells. Cytotoxicity-guided chromatographic fractionation led to the isolation of phenalamides $A_2$ and $A_3$. The producing organism was identified as Myxococcus stipitatus by taxonomic comparison with type strains of Myxococcus sp. as well as its morphological and physiological characteristics. Phenalamides$ A_1$,$ A_2$ and $A_3$ were as active against drug-resistant cancer cells CL02 and CP70 as against the corresponding sensitive cells with $IC_{50}$ values ranging from 0.23~0.57 $\mu\textrm{g}$/ml.

• Journal of Microbiology and Biotechnology
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• v.26 no.8
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• pp.1490-1503
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• 2016

Colorectal cancer (CRC) is the third most common cancer in the world. Although 5-fluorouracil (5-FU) is the representative chemotherapy drug for colorectal cancer, it has therapeutic limits due to its chemoresistant characteristics. Colorectal cancer cells can develop into cancer stem cells (CSCs) with self-renewal potential, thereby causing malignant tumors. The human gastrointestinal tract contains a complex gut microbiota that is essential for the host's homeostasis. Recently, many studies have reported correlations between gut flora and the onset, progression, and treatment of CRC. The present study confirms that the most representative symbiotic bacteria in humans, Lactobacillus plantarum (LP) supernatant (SN), selectively inhibit the characteristics of 5-FU-resistant colorectal cancer cells (HT-29 and HCT-116). LP SN inhibited the expression of the specific markers CD44, 133, 166, and ALDH1 of CSCs. The combination therapy of LP SN and 5-FU inhibited the survival of CRCs and led to cell death by inducing caspase-3 activity. The combination therapy of LP SN and 5-FU induced an anticancer mechanism by inactivating the Wnt/β-catenin signaling of chemoresistant CRC cells, and reducing the formation and size of colonospheres. In conclusion, our results show that LP SN can enhance the therapeutic effect of 5-FU for colon cancer, and reduce colorectal cancer stem-like cells by reversing the development of resistance to anticancer drugs. This implies that probiotic substances may be useful therapeutic alternatives as biotherapeutics for chemoresistant CRC.

• Nutrition Research and Practice
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• v.14 no.2
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• pp.95-101
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• 2020

BACKGROUND/OBJECTIVES: Folate plays a critical role in DNA synthesis and methylation. Intracellular folate homeostasis is maintained by the enzymes folylpolyglutamate synthase (FPGS) and γ-glutamyl hydrolase (GGH). FPGS adds glutamate residues to folate upon its entry into the cell through a process known as polyglutamylation to enhance folate retention in the cell and to maintain a steady supply of utilizable folate derivatives for folate-dependent enzyme reactions. Thereafter, GGH catalyzes the hydrolysis of polyglutamylated folate into monoglutamylated folate, which can subsequently be exported from the cell. The objective of this review is to summarize the scientific evidence available on the effects of intracellular folate homeostasis-associated enzymes on cancer chemotherapy. METHODS: This review discusses the effects of FPGS and GGH on chemosensitivity to cancer chemotherapeutic agents such as antifolates, such as methotrexate, and 5-fluorouracil. RESULTS AND DISCUSSION: Polyglutamylated (anti)folates are better substrates for intracellular folate-dependent enzymes and retained for longer within cells. In addition to polyglutamylation of (anti)folates, FPGS and GGH modulate intracellular folate concentrations, which are an important determinant of chemosensitivity of cancer cells toward chemotherapeutic agents. Therefore, FPGS and GGH affect chemosensitivity to antifolates and 5-fluorouracil by altering intracellular retention status of antifolates and folate cofactors such as 5,10-methylenetetrahydrofolate, subsequently influencing the cytotoxic effects of 5-fluorouracil, respectively. Generally, high FPGS and/or low GGH activity is associated with increased chemosensitivity of cancer cells to methotrexate and 5-fluorouracil, while low FPGS and/or high GGH activity seems to correspond to resistance to these drugs. Further preclinical and clinical studies elucidating the pharmocogenetic ramifications of these enzyme-induced changes are warranted to provide a framework for developing rational, effective, safe, and customized chemotherapeutic practices.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.1
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• pp.17-24
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• 2014

Gastric cancer is highly invasive, aggressively malignant, and amongst the most prevalent of all forms of cancer. Despite improved management strategies, early stage diagnosis of gastric cancer and accurate prognostic assessment is still lacking. Several recent reports have indicated that the pathogenesis of gastric cancer involves complex molecular mechanisms and multiple genetic and epigenetic alterations in oncogenes and tumor suppressor genes. Functional inactivation of the tumor suppressor protein PTEN (Phosphatase and Tensin Homolog) has been detected in multiple cases of gastric cancer, and already shown to be closely linked to the development, progression and prognosis of the disease. Inactivation of PTEN can be attributed to gene mutation, loss of heterozygosity, promoter hypermethylation, microRNA- mediated regulation of gene expression, and post-translational phosphorylation. PTEN is also involved in mechanisms regulating tumor resistance to chemotherapy. This review provides a comprehensive analysis of PTEN and its roles in gastric cancer, and emphasizes its potential benefits in early diagnosis and gene therapy-based treatment strategies.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.11
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• pp.6321-6326
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• 2013

Introduction: Lung cancer is extremely harmful to human health and has one of the highest worldwide incidences of all malignant tumors. Approximately 80% of lung cancers are classified as non-small cell lung cancers (NSCLCs). Cisplatin-based multidrug chemotherapy regimen is standard for such lesions, but drug resistance is an increasing problem. F-box/WD repeat-containing protein 7 (FBW7) is a member of the F-box protein family that regulates cell cycle progression, and cell growth and differentiation. FBW7 also functions as a tumor suppressor. Methods: We used cell viability assays, Western blotting, and immunofluorescence combined with siRNA interference or plasmid transfection to investigate the underlying mechanism of cisplatin resistance in NSCLC cells. Results: We found that FBW7 upregulation significantly increased cisplatin chemosensitivity and that cells expressing low levels of FBW7, such as NCI-H1299 cells, have a mesenchymal phenotype. Furthermore, siRNA-mediated silencing or plasmid-mediated upregulation of FBW7 resulted in altered epithelial-mesenchymal transition (EMT) patterns in NSCLC cells. These data support a role for FBW7 in regulating the EMT in NSCLC cells. Conclusion: FBW7 is a potential drug target for combating drug resistance and regulating the EMT in NSCLC cells.

• Journal of Yeungnam Medical Science
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• v.13 no.1
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• pp.11-21
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• 1996

항암치료에 있어 내성기전은 암세포의 종류에 따라 다양하며 동일세포라도 내성이 생긴 항암제에 따라 그 기능이 다른 것으로 보고되고 있으며 세포종류 및 항암제에 따른 각각의 내성기전을 완전히 알기란 그리 쉬운 일이 아니다. 그러나 임상치료에 있어서 항암제의 적용은 대개 내성 생성이 잘 안되는 즉 교차내성이 적게 일어나는 약제끼리의 선택이 화학요법에 유리하며 재발방지의 지표가 될 수 있으며 내성억제가 가능한 약제의 개발이 중요하다. 또 암에 따른 정확한 내성기전을 잘 밝힘으로서 내성을 방지할 수 있는 target 약제를 함께 병용 개발하는 것이 암의 치료의 지름길이 될 수 있다.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.3
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• pp.1145-1148
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• 2014

Background: Single pegylated liposomal doxorubicin (PLD) is commonly used as a salvage treatment in platinum-resistant ovarian cancer, fallopian tube cancer and primary peritoneal adenocarcinoma (PPA) with a satisfactory outcome. However, the data for second generation PLD administered in this setting are still limited. We conducted a retrospective study to evaluate the outcome of patients who received single-agent second generation PLD (LIPO-DOX) after the development of clinical platinum resistance. The study period was between March 2008 and March 2013. LIPO-DOX was administered intravenously 40 $mg/m^2$ every 28 days until disease progression, but for not more than six cycles. The response rate was evaluated using the Gynecologic Cancer Intergroup (GCIG) criteria while the toxicity was evaluated according to WHO criteria. Twenty-nine patients met the inclusion criteria in the study period with an overall response rate of 13.8%. The median progression free survival and overall survival were three and eleven months, respectively. With the total of 96 cycles of chemotherapy, the patients developed grades 3 and 4 hematologic toxicity as follows: anemia, 0%, leukopenia, 9.6%, neutropenia, 32.3% and thrombocytopenia, 0%. In conclusion, the single agent second generation PLD demonstrated modest efficacy in patients with platinum-resistant ovarian cancer, fallopian tube cancer and PPA without serious toxicity.