Clinical overview: adjuvant therapy of gastrointestinal cancer

Adjuvant therapy has been tested widely in the treatment of cancers of the stomach, pancreas, and large bowel. In the USA, the use of postoperative chemoradiation in stomach cancer is considered a standard of care after the publication of the Intergroup Study 0116 in September 2001. This study demonstrated significant benefit in overall and disease-free survival for patients receiving postoperative treatment with fluorouracil (5-FU)/leucovorin chemotherapy and radiation after gastric resection. Adjuvant chemotherapy is not considered to be of significant benefit, and such therapy for patients with resected gastric cancer is investigational. There is interest in the use of neoadjuvant chemotherapy strategies as preoperative treatment followed by surgical resection. This approach has been tested in a randomized study of over 500 patients carried out by the Medical Research Council in the UK. This study demonstrated that patients receiving preoperative and postoperative epirubicin, cisplatin, 5-FU (ECF) chemotherapy, had a downstaging of tumor size, an increase in rates of curative resection, and an increase in disease-free but not overall survival. With pancreatic cancer, there is a controversy over postoperative chemoradiation after pancreatic resection. A recently completed Intergroup Study compared gemcitabine to 5-FU chemotherapy given before and after radiation in resected pancreatic cancer. Over 500 patients have been accrued to this study, which recently closed. In Western Europe, the results of a large clinical trial (ESPAC) have suggested that chemoradiation is not beneficial in patients with resected pancreatic cancer. In large bowel cancer, 5-FU-based adjuvant chemotherapy regimens are superior to surgery alone, particularly in node-positive patients. The use of newer combinations including 5-FU/leucovorin plus irinotecan and 5-FU/ leucovorin plus oxaliplatin are also of interest as chemotherapy in resected colon cancer patients. The recent publication of the MOSAIC trial demonstrated that 5-FU/leucovorin/oxaliplatin (FOLFOX 4) improves progression-free survival in node-positive patients over 5-FU/leucovorin alone. The results of studies of 5-FU/ leucovorin and irinotecan both in Europe (PETACC) and the USA (IFL vs 5-FU/leucovorin) are awaited with interest. Another area of interest in resected colon cancer is the use of molecular genetic monitoring to assess the likelihood of patient relapse. The data over the past several years have demonstrated that patients whose tumors do not have deletion of the deleted in colon cancer (DCC) gene on chromosome 18 have an improved outcome. Recent data are available with tumors that demonstrate microsatellite instability (MSI). Such tumors represent about 15% of all colon cancers and have an improved outcome when compared to those not expressing MSI, and may not benefit from adjuvant chemotherapy.     

5-fluorouracil: mechanisms of action and clinical strategies

5-fluorouracil (5-FU) is widely used in the treatment of cancer. Over the past 20 years, increased understanding of the mechanism of action of 5-FU has led to the development of strategies that increase its anticancer activity. Despite these advances, drug resistance remains a significant limitation to the clinical use of 5-FU. Emerging technologies, such as DNA microarray profiling, have the potential to identify novel genes that are involved in mediating resistance to 5-FU. Such target genes might prove to be therapeutically valuable as new targets for chemotherapy, or as predictive biomarkers of response to 5-FU-based chemotherapy.     

Involvement of Nrf2 activation in resistance to 5-fluorouracil in human colon cancer HT-29 cells

Acquisition of drug resistance by cancer cells is attributed to various factors including alterations in apoptotic pathways, enhanced expression of multidrug resistance-associated proteins, altered drug metabolism or uptake and/or overexpression of cytoprotective genes. Thus, potential induction of defence pathways by anticancer drugs might have a marked incidence on cancer cell resistance. 5-Fluorouracil (5-FU) remains the most commonly used anticancer drug for the treatment of colorectal cancer, although objective response rates are as low as 20%. The aim of our study was to investigate the effects of 5-FU on cytoprotective systems in human colon HT-29 cells. Our results demonstrate that 5-FU induced the expression of mRNAs encoding glutathione transferases and antioxidant enzymes. To further determine the mechanisms involved in 5-FU effects, we investigated whether it activates the Nrf2/antioxidant response element pathway which is implicated in the regulation of several genes involved in cytoprotection. Translocation of Nrf2 into the nucleus after 5-FU exposure was demonstrated by immunocytochemistry and western blotting. Using an ARE-driven reporter gene assay, activation of the luciferase activity by 5-FU was also evidenced. Moreover, transfection of HT-29 cells with siRNA directed against Nrf2 inhibited induction of Nrf2 target genes and increased 5-FU cytotoxicity. In conclusion, we demonstrate for the first time that 5-FU activates the Nrf2/ARE pathway which in turn induces cytoprotective genes and modulates chemosensitivity of HT-29 colon cancer cells. Therefore, we postulate that Nrf2 might represent a potential therapeutic target in 5-FU treatment of colon cancer.     

Prediction of chemosensitivity of colorectal cancer to 5-fluorouracil by gene expression profiling with cDNA microarrays

5-Fluorouracil (5-FU) is the most widely used anticancer agent for gastrointestinal cancers. Because many tumors show primary resistance, it is clinically meaningful to predict tumor sensitivity to the drug before treatment. cDNA microarrays containing 21,168 clones were used to identify genes associated with sensitivity to 5-FU. Gene expression profiling of 3 colorectal cancer cell lines (DLD-1, HT-29 and NUGC-3) and the corresponding 5-FU-resistant sublines (DLD-1/FU, HT-29/FU and NUGC-3/5FU/L) showed 81 genes that were differentially expressed. The gene set thus identified successfully predicted the sensitivities of 5 other colorectal cancer cell lines and could also separate 5-FU resistant clinical samples from sensitive ones.     

Role for alpha1,2-fucosyltransferase and histo-blood group antigen H type 2 in resistance of rat colon carcinoma cells to 5-fluorouracil

5-Fluorouracil (5-FU) is a drug of standard use in chemotherapy of colon carcinoma. However, its efficacy is limited by inherent and acquired cell resistance. Major changes in histo-blood group antigenic expression, at times associated with poor prognosis, occur on colon cancer cells. To assess whether these antigens might play a role in the resistance to 5-FU, a rat model of colon carcinoma was used. We observed that in vivo treatment of tumors with the drug increased expression of antigen H type 2. The increase was also observed after in vitro short-term exposure to 5-FU, as well as on a cell-resistant variant selected by continuous exposure to the drug, and was accompanied by an increase in alpha1,2-fucosyltransferase activity, the key enzyme involved in synthesis of H antigens. Transfection of cells devoid of this enzymatic activity by an alpha1, 2-fucosyltransferase cDNA allowed expression of H type 2 antigen and increased resistance to 5-FU. Inversely, transfection of cells which possess enzymatic activity by a cDNA in anti-sense orientation reduced both H type 2 cell-surface antigen and resistance to the drug. These results demonstrate that, in this experimental model, alpha1,2-fucosyltransferase and H type 2 antigen are involved in cellular resistance to 5-FU.     

Recent advances is surgical adjuvant chemotherapy for colorectal cancer

To evaluate the significance of surgical adjuvant chemotherapy, randomized controlled trials (RCTs) of adjuvant chemotherapy after curative resection for colorectal cancer were reviewed. Several multi-drug systemic chemotherapies (MOF, MMC/FT, 5-FU, UFT p.o.) were useful as adjuvant treatment to improve survival or disease-free survival of patients with colorectal cancer. Moreover, a worldwide meta-analysis suggested that continuous intraportal 5-FU infusion improves survival. Combination chemotherapy trials utilizing 5-FU and levamisol (LEV) demonstrated a survival advantage in patients with high risk colon cancer. Recently, many RCTs have substantiated the benefits of treatment with 5-FU/Leucovorin (LV) and this treatment is widely used as adjuvant treatment for the patients with Dukes C resected colon cancer in Europe and the U.S.A. Now, with the increasing use of oral chemotherapy drugs, new trials comparing oral UFT/LV with intravenous 5-FU/LV are being implemented to investigate these drugs in terms of QOL, toxicity and cost. Furthermore, the new drug irinotecan (CPT-11) is now under investigation to see if it brings added efficacy to 5-FU/LV. In Japan, two major groups (N-SAS-CC and TAC-CR) are comparing surgery alone and UFT alone in patients with Dukes C colon and rectal cancer. From these results, surgical adjuvant chemotherapy seems to be effective in the treatment of patients with high risk colon cancer and those with rectal cancer.     

Acquired resistance of pancreatic cancer cells towards 5-Fluorouracil and gemcitabine is associated with altered expression of apoptosis-regulating genes

OBJECTIVES: Resistance to chemotherapy is a major cause of treatment failure and poor prognosis in pancreatic cancer. Inasmuch as most effects of chemotherapeutic agents are mediated via the activation of apoptosis, the cytotoxic effects of gemcitabine and 5-fluorouracil (FU) in correlation with apoptosis-regulating genes in pancreatic cancer cell lines were analyzed. METHODS: The cytotoxic effects of 5-FU and gemcitabine in AsPC-1, Capan-1, Mia-PaCa-2 and T3M4 pancreatic cancer cell lines were assessed by growth assays, and mRNA expression levels of pro-apoptotic and anti-apoptotic genes of the Bcl-2 family were analyzed by RNAse protection assays. RESULTS: Pancreatic cancer cells displayed a wide range of responses towards 5-FU (IC(50) 0.22-4.63 microM) and gemcitabine (11.51-42.2 nM). After repeated treatment with 5-FU, the IC(50) values in Capan-1 and T3M4 cells increased 2.1- and 1.8-fold, respectively, compared to their parental cells. Following recurrent treatment with gemcitabine, the IC(50) values in Capan-1 cells increased significantly (1.5-fold, p < 0.01). RNase protection assay showed a negative correlation between bcl-x(L) and mcl-1 mRNA expression levels and the sensitivity to 5-FU and gemcitabine after 5-FU and gemcitabine treatment. The bax/bcl-2 ratio maintained relatively stable following 5-FU/gemcitabine treatment and reflected the chemotherapeutic sensitivity of these cell lines. CONCLUSIONS: These findings reveal that pancreatic cancer cell lines are generally resistant to 5-FU and are more sensitive towards gemcitabine. The bax/bcl-2 ratio is predictive of chemotherapy sensitivity, whereas bcl-x(L) and mcl-1 mRNA levels following repeated exposure to 5-FU or gemcitabine are associated with resistance to these drugs. These findings suggest that the activation of anti-apoptotic genes after repeated drug exposure contributes to chemoresistance of pancreatic cancer cells and that blockage of anti-apoptotic genes might enhance chemosensitivity in pancreatic cancer.     

Down-Regulation of BAX Gene During Carcinogenesis and Acquisition of Resistance to 5-FU in Colorectal Cancer

Carcinogenesis and resistance to chemotherapy could be as results of expression variations in apoptosis regulating genes. Changes in the expression of apoptosis interfering genes may contribute to colorectal carcinogenesis and resistance to 5-Flourouracil (5-FU) during treatment schedule period. The present study aimed to evaluate the expression of pro-apoptotic and anti-apoptotic genes in colorectal cancer tumor tissues, normal adjacent tissues, and tumor colorectal cancer cell line during acquiring resistance to 5-FU in HT-29 based on Bolus treatment protocol. The normal and tumor tissues were obtained from hospital after surgery and total RNA was extracted for expression analysis. The HT-29 colorectal cancer cell line was cultured and exposed with 5-FU in three stages based on Bolus protocol. The MTT assay and Real Time PCR were carried out to determine the sensitivity to the drug and expression of desired genes, respectively. The obtained data showed that Proapoptotic genes, BAX and BID, were down-regulated in resistant derivate cells compared to wild type HT-29 cells. On the other hand Antiapoptotic genes, CIAP1 and XIAP, showed upregulation in resistant cells compared to wild type ones. Furthermore, BAX and FAS genes showed down-regulation in tumor samples in comparison to normal adjacent tissues. In conclusion, the results of our study suggest that BAX down-regulation could contribute as an important factor during both colorectal carcinogenesis and cell resistance to 5-FU.     

Molecular determinants of response to 5-fluorouracil-based chemotherapy in colorectal cancer: The undisputable role of micro-ribonucleic acids

5-flurouracil (5-FU)-based chemotherapy is the main pharmacological therapy for advanced colorectal cancer (CRC). Despite significant progress in the treatment of CRC during the last decades, 5-FU drug resistance remains the most important cause of failure in CRC therapy. Resistance to 5-FU is a complex and multistep process. Different mechanisms including microsatellite instability, increased expression level of key enzyme thymidylate synthase and its polymorphism, increased level of 5-FU-activating enzymes and mutation of TP53 are proposed as the main determinants of resistance to 5-FU in CRC cells. Recently, micro-ribonucleic acids (miRNA) and their alterations were found to have a crucial role in 5-FU resistance. In this regard, the miRNA-mediated mechanisms of 5-FU drug resistance reside among the new fields of pharmacogenetics of CRC drug response that has not been completely discovered. Identification of the biological markers that are related to response to 5-FU-based chemotherapy is an emerging field of precision medicine. This approach will have an important role in defining those patients who are most likely to benefit from 5-FU-based chemotherapy in the future. Thereby, the identification of 5-FU drug resistance mechanisms is an essential step to predict and eventually overcome resistance. In the present comprehensive review, we will summarize the latest knowledge regarding the molecular determinants of response to 5-FU-based chemotherapy in CRC by emphasizing the role of miRNAs.     

Chemotherapy for pancreatic cancer

Pancreatic cancer has one of the worst prognosis of any malignant disease. The National Registry of Japan Pancreas Society has reported that only 13% of patients achieve 5 years survival after surgical resection. The vast majority of patients present with metastatic or unresectable disease. Gemcitabine (GEM) has replaced 5-fluorouracil (5-FU)-based chemotherapy as the standard of care. GEM first generated improvements in symptom control and survival in advanced disease, spurring further research. For locally advanced disease, most recent studies have incorporated GEM into combined-modality therapy. However, subsequent trials have not demonstrated that combinations of other agents with GEM extend clinical benefits yet. Similarly, in surgically resectable disease, current trials are incorporating GEM into adjuvant therapy. According to several clinical trials it has been demonstrated that improvements in locoregional control and survival may be achieved when chemotherapy using 5-FU is added to radiation for locally advanced pancreatic cancer. The new regimen for locally advanced disease has demonstrated that the better outcome is expected by chemoradiation therapy with 5-FU followed by GEM treatment. Furthermore, one of the patients showed the significant regression of pancreas tumor, resulting in the successful surgical resection. In order to develop chemotherapy for pancreatic cancer, we are analyzing mRNA expression of pancreas cancer cell lines and examined their resistant against to GEM. One of the genes is demonstrated to be a responsible for drug sensitivity by clustering analysis.     

Predicting the chemosensitivity of pancreatic cancer cells by quantifying the expression levels of genes associated with the metabolism of gemcitabine and 5-fluorouracil

Gemcitabine (GEM) is the standard treatment for advanced/metastatic pancreatic cancer. However, there is a substantial subset of patients in whom the efficacy of GEM, when used as a single agent, is inadequate. Recently, the 5-fluorouracil (5-FU) prodrugs capecitabine and S-1 have been used as an alternative, either alone or in combination with GEM. The aim of the present study was to investigate the expression pattern of genes that render pancreatic cancer cells sensitive to GEM and 5-FU, and to identify markers for individualized chemotherapy, even in patients who have developed resistance. We investigated the correlation between the expression of genes associated with the metabolism of GEM and 5-FU, and sensitivity to these drugs in 15 human pancreatic cancer cell lines. We also established GEM- and 5-FU-resistant pancreatic cancer cell lines to investigate changes in the expression levels of these genes and the effects of one drug on cells resistant to the other. We found no correlation between pancreatic cancer cell sensitivity to either GEM- or 5-FU. GEM-resistant cells did not become resistant to 5-FU and vice versa. High expression of RRM1 (P=0.048) and TS x DPD (P=0.035) correlated significantly with sensitivity to GEM and 5-FU, respectively. 5-FU-resistant cells expressed significantly higher levels of TP than parental cells (P<0.05). In conclusion, pancreatic cancer cells showed no cross-resistance to GEM and 5-FU. Quantitative analyses of RRM1, TP, DPD and TS mRNA levels in pancreatic cancer cells may be useful for predicting their sensitivity to GEM and 5-FU.     

三维培养药敏实验测定的胃癌药物敏感性与多药耐药基因蛋白表达的关系

背景与目的：目前胃癌化疗疗效尚不理想,通过预测个体肿瘤对药物的敏感性来指导临床治疗,以提高疗效,早已成为化疗界瞩目的问题。本研究通过三维培养药敏实验测定胃癌的药物敏感性,并通过测定多药耐药基因表达产物水平,分析两者之间的关系。方法：应用三维培养体外药敏实验技术,测定表阿霉素、顺铂、草酸铂、5-FU、泰素帝、伊立替康6种单药和5-FU＋表阿霉素＋顺铂、5-FU＋伊立替康、5-FU＋草酸铂、5-FU＋泰素帝＋顺铂4组联合用药对22例胃癌组织的抑制率,并计算敏感率;应用逆转录聚合酶链反应（RT—PCR）和免疫组化法检测胃癌组织中MDR1、MRP1、ABCG2基因蛋白的表达。结果：单药组中5-FU对胃癌组织的抑制率和敏感率最高,分别为29．8％和50．0％：联合用药组抑制率最高为5-FU＋泰素帝＋顺铂（59．8％）,敏感率最高为5-FU＋表阿霉素＋顺铂（77．3％）;联合用药组抑制率和敏感率均高于单药组（P〈0．05）。胃癌组织中MDR1、MRP1、ABCG2 mRNA的阳性率分别为90．9％、54．5％、77．3％,MDR1、MRP1、ABCG2蛋白的阳性率分别为36．4％、54．5％、36．4％;多药耐药蛋白高表达与胃癌对表阿霉素的耐药有相关性（P〈0．05）。结论：胃癌组织中多药耐药基因MDR1、MRP1、ABCG2蛋白高表达与胃癌组织对表阿霉素的耐药有关。提示这三种耐药基因可能参与介导表阿霉素的耐药。     

Successful management of the recurrent esophageal cancer following esophagectomy at a different time with combined local treatment of chemoradiotherapy and hepatic arterial infusion chemotherapy

A 63-year-old man who underwent radical resection for esophageal cancer (cStage III)was diagnosed with metastasis of the paraaortic lymph node 5 months after the surgery. He was treated with concomitant chemoradiotherapy (CRT)with low-dose FP(5-FU, CDDP)and 60 Gy of irradiation. The effect of CRT was a complete response. Seven months later, there was a metastasis to the liver(S4). He received systemic chemotherapy(5-FU, ADR, CDDP: FAP), but it was not effective, so hepatic arterial infusion chemotherapy(FAP)was performed. Hepatic artery infusion therapy( 5-FU 1,000 mg/3.5 h x ADR 10 mg/1 h x CDDP 10 mg/1 h)was given for 1 day at an interval of 2 weeks for 18 months. Since ADR reached the maximum dose, hepatic artery infusion of 5-FU(1,000 mg/3.5 h)and CDDP(10 mg/ 1 h)was continued for 14 months at an interval of 4 weeks. The recurrent lesion disappeared completely 9 months after beginning hepatic artery infusion therapy. The patient is alive 69 months after surgery without any evidence of recurrence. Most cases with recurrent esophageal cancer have multiple metastases, and the treatment is mainly systemic therapy. However, in a patient with recurrent tumors at different times, it is possible to achieve a complete response and long-time survival by local treatment with fewer side effects as in this case. Combined local treatments could be the second treatment option after failed systemic chemotherapy for recurrent tumors in patients with esophageal cancer. Further investigations are necessary.     

干预自噬影响DPD的表达促进5-FU抗结直肠癌疗效的实验研究

背景与目的：结直肠癌作为常见的消化系统恶性肿瘤之一,其化疗与耐药一直以来备受关注,5-氟尿嘧啶（5-fluorouracil,5-FU）是结直肠癌的一线化疗药物,其疗效常因耐药或不良反应而受到影响。二氢嘧啶脱氢酶（dihydropyrimidine dehydrogenase,DPD）是5-FU代谢的关键限速酶,其表达或降解可能成为影响5-FU疗效的因素。自噬是细胞内蛋白质代谢的重要途径,其在化疗诱导的细胞死亡或增殖抑制中的作用仍存在争议。本研究旨在探讨自噬在结直肠癌化疗过程中的作用以及干预自噬影响5-FU耐药的机制。方法：体外细胞培养人结肠癌HCT-8、COLO205、LOVO和SW480细胞系,观察不同细胞系中DPD的表达对5-FU敏感性的影响,通过药物敏感性实验筛选出5-FU敏感细胞,检测5-FU敏感细胞株及其相对应的耐药细胞株中DPD的表达、自噬水平及自噬关键因子微管相关蛋白轻链3（light chain 3,LC3）、P62的表达,并通过诱导/抑制细胞自噬,观察调控自噬状态对DPD的表达变化以及肿瘤细胞生物学行为和化疗抵抗能力的影响,通过UbiBrowser数据库筛选及免疫共沉淀实验（co-inmunoprecipitation,Co-IP）实验验证DPD降解过程中的E3连接酶,探讨自噬降解DPD逆转5-FU耐药的分子机制。结果：DPD低表达的细胞系对5-FU的敏感性更强,其中COLO205细胞系在4种细胞中DPD表达量最高,并对5-FU的耐药性最强,而HCT-8细胞DPD表达最低并对5-FU最为敏感。与HCT-8细胞相比,HCT-8/FU耐药细胞表达较高水平的DPD,以及较低的基础自噬水平;雷帕霉素（rapamycin,RAPA）介导的自噬激活增强了细胞的自噬水平,降低了DPD表达,同时降低了细胞增殖、侵袭和5-FU耐药性;3甲基腺嘌呤（3-methyladenine,3-MA）及羟氯喹（hydroxychloroquine,HCQ）介导的自噬抑制减弱了细胞的自噬水平,增加了DPD表达,增强了5-FU耐药性。5-FU与自噬激活剂联合应用对细胞的抑效果要远远强于单用5-FU及与自噬抑制剂联合应用的效果;DPD的降解需要完整的自噬流的参与,其中自噬溶酶体的形成是DPD降解的关键步骤之一,而单一的自噬体无法对DPD进行降解。E3连接酶NEDD4在HCT-8/5-FU细胞中与DPD和P62蛋白免疫共沉淀,在DPD的自噬降解中发挥作用。结论：自噬参与DPD降解影响结直肠癌细胞对化疗药物的敏感性,激活自噬可促进DPD降解和抑制5-FU的分解代谢,可能成为逆转结直肠癌5-FU耐药的新途径。     

Therapeutic strategy for marginally resectable esophageal cancer

A marginally resectable tumor is defined as a tumor for which the combined resection of surrounding organs is recommended. Esophageal cancer often invades key organs, such as the trachea, bronchus, and aorta, and the preservation of laryngeal function is an important issue when there are tumors located at the cervical esophagus. For marginally resectable tumors of the esophagus, a multimodality treatment should be recommended, because a single-modality treatment cannot cure such advanced diseases. The concept of the treatment strategy is R0 resection after obtaining the down-staging by neoadjuvant treatment. To date, chemoradiation therapy or the combination of chemotherapy and radiotherapy, followed by surgery has been the most promising therapeutic strategies for marginally resectable esophageal cancer. However, there are concerns that must be addressed: the efficacy of 5-FU and cisplatin-based chemotherapy for obtaining control of the disease locally, and the risks and benefits of salvage surgery after chemoradiation therapy. To overcome these problems and to improve the prognosis of patients with marginally resectable tumor of the esophagus, it is necessary to develop new strategies with new regimens of chemotherapy, such as the combined use of docetaxel with 5-FU and cisplatin, to achieve more powerful local control and use of induction chemotherapy, and to validate the safety and efficacy of the salvage surgery.     

A case of advanced gallbladder cancer responding to neoadjuvant intra-arterial chemotherapy

The patient was a 52-year-old female who had been diagnosed as advanced gall bladder cancer by various imaging studies. The cancer responded to neoadjuvant intra-arterial chemotherapy and was curatively resected. Since cancer had invaded the median widely, the posterior and the lateral segments of the liver according to CT imaging, neoadjuvant chemotherapy was used. The combination chemotherapy included intra-arterial chemotherapy (CDDP 10 mg + 5-FU 250 mg/day/week x5 times, EPI 10 mg + 5-FU 250 mg/day/week x3 times) through the hepatic artery and oral chemotherapy (UFT 300 mg/day for 106 days). No severe side effects were found during this chemotherapy. Imaging studies after the chemotherapy showed a partial response (PR) and curative resection (hepato-pancreato-duodenectomy with regional lymph nodes dissection) could be performed successfully. She has been disease-free without any sign of recurrence for 18 months after surgery. We conclude that this combination chemotherapy will be useful for advanced gall bladder cancer if the appropriate combinations, dosages, and administration routes are chosen.     

Identification of novel genes associated with the response to 5-FU treatment in gastric cancer cell lines using a cDNA microarray

The 5-Fluorouracil (5-FU) is an anticancer drug that is widely used in the treatment of cancer. To identify novel genes associated with 5-FU in gastric cancer, the time-dependent expression profiling of genes in response to 5-FU was examined in 5-FU sensitive and/or resistant gastric cancer cell lines using a 'KUGI 14 K cDNA chip' containing 14,081 unigenes obtained from human gastric cancer cell lines and tissues. By this analysis, we obtained 13 genes which are directly associated with sensitivity or resistance to 5-FU. Of these genes, 11 were found to be commonly up-regulated only in the 5-FU sensitive cell lines, and 2 were oppositely regulated in both of 5-FU sensitive and resistant cell lines. These genes were determined to be involved in cell surface, apoptosis, cell cycle and signal transduction. Of these genes, the expression levels of ZFP100, 4F2hc, FLJ11021, CSTF3, PPP1R14A, DDB2, C6orf139, CDKN1A, HOXC11 and FLJ38860 were confirmed by semi-quantitative RT-PCR. In addition, seven genes containing RRMI, UP1 and K-EST0037597 were found to be commonly up-regulated in both cell lines. In addition, the expression of genes such as TP, OPRT, TS and DPD, which have been previously known to be involved in 5-FU metabolism, were examined in both of 5-FU sensitive and resistant cell lines. These results provide not only predictive biomarkers for 5-FU sensitivity or resistance to human gastric cancer, but also a new molecular basis for understanding the mechanism of cellular cytoxicity to 5-FU.     

Current status of adjuvant chemotherapy of gastric cancer

Effect of adjuvant chemotherapy on the postoperative survival of gastric cancer patients has been suggested by various clinical trials with an aim of controlling minimum residual tumors after surgery. Incorporation of adjuvant chemotherapy with MMC, 5-FU, FT-207, or immunomodulators into the treatment modalities might be one of the basic treatment strategies for gastric cancer. Well designed, controlled trials in terms of selecting proper drugs and patients, and of statistical methodology, are essential for the proper evaluation of the adjuvant chemotherapy.