奥曲肽逆转肝细胞肝癌多药耐药的机制

目的 探讨生长抑素（SST）类似物奥曲肽逆转肝癌细胞多药耐药可能的机制。方法 应用MTT法分析肝癌细胞对化疗药物的敏感性;RT—PCR、流式细胞术检测肝癌细胞多药耐药基因多药耐药糖蛋白1（MDR1）、多药耐药相关蛋白2（MRP2）mRNA及其蛋白质的表达。结果 奥曲肽联合化疗药物可以显著降低化疗药物的IC50肝癌细胞有生长抑索受体2（SSTR2）、生长抑素受体3（SSTR3）、MDR1、MRP2的表达,奥曲肽可显著降低肝癌细胞表面MDR1、MRP2的表达。结论 SST可与肝癌细胞表面的SSTR结合,降低其表面MDR2、MRP2的表达,使细胞内细胞毒药物浓度增加,从而逆转肝癌细胞多药耐药。     

Expression of cyclooxygenase-2 protein in colorectal carcinomas

Summary Background. Overexpression of cyclooxygenase-2 (COX-2) has been demonstrated in various human cancers, including colorectal cancer. Thus, overexpression of COX-2 may be involved in the growth and progression of cancer, and this may have prognostic significance. Aim. The aim of our study is to evaluate the expression of COX-2 in colorectal cancer tissue, and to examine the relationship of its expression to various clinicopathological parameters and patient survival. Methods. Formalin-fixed, paraffin-embedded tissue blocks were obtained from 60 patients who underwent surgery for colorectal carcinoma in 1995 at the Chonnam National University Hospital in Gwangju, Korea. We have used an immunohistochemical technique to localize COX-2 in colorectal carcinoma tissues. Results. Immunohistochemical staining of the colorectal cancer specimens demonstrated that COX-2 expression was localized to the carcinoma cells and was not detectable in the stromal compartment of the cancers. The COX-2 immunostaining pattern was predominantly homogenous, and perinuclear cytoplasmic within the tumors. Normal colonic epithelium adjacent to the tumor showed no staining for COX-2. The COX-2 protein was detected in 70% (42/60) of colorectal carcinoma tissues. However, no significant correlation was found between COX-2 expression and various clinicopathological parameters, including histologic grade, tumor size, depth of invasion, lymph node metastasis, distant metastasis, or stage. Furthermore, COX-2 expression did not correlate with patient survival (p=0.401). Conclusion. These results suggest that COX-2 expression may play an important role in the evolution of colon carcinogenesis. However, further studies are needed to determine the prognostic relevance of COX-2.     

结直肠癌组织中PI3KCB蛋白表达及其与多药耐药基因产物的相关性

目的观察PI3KCB蛋白在结直肠癌组织中的表达情况,并探讨其与结直肠癌多药耐药(MDR)基因产物的相关性。方法采用免疫组化SP法检测128例结直肠癌组织、10例正常结肠黏膜组织中的PI3KCB蛋白及MDR基因产物LRP、GST-π、TopoⅡ。结果结直肠癌组织中PI3KCB蛋白呈阳性表达者105例(82.03%),正常结肠黏膜组织呈阳性表达者1例(10.00%),两者相比,P<0.01。结直肠癌组织中PI3KCB蛋白的表达与肿瘤发生部位、分化程度、临床分期及淋巴结转移有关(P均<0.05)。结直肠癌组织中LRP、GST-π、TopoⅡ呈阳性表达者分别为106例(82.81%)、120例(93.75%)、68例(53.13%),PI3KCB蛋白的表达与GST-π的表达呈正相关(rs=0.207,P<0.05)。结论 PI3KCB在结直肠癌组织中表达增加,与结直肠癌的发生发展及MDR密切相关;检测PI3KCB蛋白对于判断结直肠癌的生物学行为以及合理筛选有效的化疗药物具有重要参考价值。     

P-glycoprotein, lung resistance-related protein and multidrug resistance associated protein in de novo acute non-lymphocytic leukaemias: biological and clinical implications

P-glycoprotein (PGP), lung resistance-related protein (LRP) and multidrug resistance associated protein (MRP) expression and the blast cells' intracellular daunorubicin accumulation (IDA) were evaluated in 96 previously untreated cases of de novo acute non-lymphocytic leukaemia (ANLL). 47/96 patients (49%) were classified as PGP+ 44/ 96 (46%) as LRP+, and 8/96 (8%) as MRP+. The more frequent MDR clusters were PGP-/LRP-/MRP- (32/96 cases, 33%) and the PGP+/LRP+/MRP- (27/96 cases, 28%) followed by PGP+/LRP-/MRP- (15/96 cases, 16%) and PGP-/LRP+/MRP- (14/96 cases, 14%). A favourable karyotype was observed more frequently in PGP- and LRP-cases. A highly significant correlation was found between either PGP or LRP overexpression and leukaemic blast cell IDA. All the patients received standard induction and consolidation treatments containing MDR-related (idarubicin, mitoxantrone, etoposide) and other (arabinosyl cytosine) drugs. Multivariate analysis showed that PGP overexpression was significantly associated with a poor response to treatment, both in terms of primary resistance or shorter survival. Other independent prognostic factors were age and cytogenetics. LRP overexpression did not reach statistical significance, although for LRP+ cases the trend was unfavourable. Due to small numbers, no conclusion could be made regarding MRP overexpression, but 5/8 cases showed unfavourable karyotypic abnormalities, 8/8 had a defective IDA and 6/8 failed to achieve remission. This study showed that both PGP and LRP overexpression are common features in de novo ANLL at onset whereas MRP overexpression is more rare. It suggested that overexpression of one of the MDR related proteins was associated with a defective IDA, and confirmed that, in addition to age and cytogenetics, PGP retains an independent prognostic value. It also suggested that LRP did not affect clinical outcome when patients were treated with idarubicin or mitoxantrone and arabinosyl cytosine.     

Extended multidrug resistance in haemopoietic cells

The development of drug resistance was studied in a series of haemopoietic cells to determine its relationship to cell lineage. Treatment of the U937 monocytic cell line with epirubicin (15 ng/ml) or vinblastine (8 ng/ml) induced drug-resistant sublines with cross-resistance to epirubicin (8- and 16-fold respectively), vinblastine (5- and 20-fold), paclitaxel (15-and 42-fold) and etoposide (19- and 13-fold). However, sublines were also 3–5-fold resistant to the alkylating agent chlorambucil, cis-platinum and methotrexate, demonstrating an extended multidrug resistance (MDR) phenotype. These cells over-expressed P-glycoprotein, but decreased drug accumulation was not restored in the presence of verapamil, suggesting that the P-glycoprotein was not functional. Similar drug treatment of the HL60 promyelocytic cell line also produced sublines exhibiting an extended MDR phenotype. The KG1a and the HEL cell lines expressed functional P-glycoprotein and were resistant to the drug concentrations used for treatment. Multidrug resistance as mediated by P-glycoprotein cannot explain the resistance of CML patients to chemotherapy, especially in blast crisis. The induction of an extended MDR phenotype specifically in myeloid cells in response to drug treatment may explain the resistance observed in the treatment of CML.     

Expression of the multidrug resistance-associated protein in myelodysplastic syndromes

In the myelodysplastic syndromes (MDS), P-glycoprotein (P-gp) expression is clinically associated with drug resistance, whereas the clinical significance of multidrug resistance-associated protein (MRP1) is uncertain. Bone marrow from 56 patients with MDS, including six with refractory anaemia (RA)/RA with ringed sideroblasts (RARS), 23 cases of RA with excess blasts/in transformation (RAEB/T), four patients with chronic myelomonocytic leukaemia (CMML) and 23 cases of MDS having progressed to acute myeloid leukaemia (MDS-AML), were studied. MRP1 expression was investigated by immunocytochemistry (ICC) and by flow cytometry using MRPm6 monoclonal antibody. The efflux test using calcein-AM (CAM) +/- probenecid to evaluate MRP1 activity was performed in ten of the 56 patients. Twenty-eight of the 56 cases (50%) expressed MRP1. MRP1 expression was more frequent in MDS-AML than in MDS (70% vs. 36%). The efflux test using CAM was positive in three out of the ten patients tested. The results were in agreement with expression of MRP1 in six cases, and were discordant in four cases (1 MRP-/CAM+, 3 MRP+/CAM-). No correlation was observed between MRP1 expression and P-gp, lung resistance-associated protein (LRP) or CD34 expression, although there was a trend for more frequent MRP1 expression in P-gp-positive cases in MDS-AML (P = 0.08). Ten of the 26 patients treated with intensive chemotherapy achieved complete remission including six out of 16 MRP1+ and four out of ten MRP1- cases (P = NS). In conclusion, MRP1 expression was correlated with disease stage in MDS in our study. As for P-gp, discordant expression/function of MRP1 could be found in some cases, suggesting the existence of non-functional transport proteins in MDS. MRP1 expression did not seem to be a prognostic factor in MDS in our experience.     

Toll样受体4及Tollip蛋白在大肠癌中的表达及临床意义

目的探讨Toll样受体4（TLR4）及Tollip蛋白在大肠癌发生、发展过程中的作用。方法采用免疫组化SP法检测TLR4和Tollip蛋白在51例大肠癌癌组织和20例癌旁正常组织中的表达,并分析两者与大肠癌临床分期、病理分级的相关性。结果TLR4及Tollip蛋白在大肠癌组织中的表达显著强于癌旁正常组织,且两者表达随肿瘤临床病理分期进展及病理分级降低而升高（P〈0．01）。结论TLR4、Tollip蛋白在大肠癌发生、发展过程中发挥一定免疫作用,可作为判断大肠癌进展程度的参考指标。     

Multidrug resistance associated protein 2 mediates transport of prostaglandin E2.

BACKGROUND/AIM: Inactivation of prostaglandin E(2) (PGE(2)) in the liver is a rapid process and occurs mainly through beta-oxidation in the peroxisome of the hepatocyte. Biliary excretion of PGE(2) is also a means of elimination from the liver. We investigated the role of multidrug resistance-associated protein 2 (MRP2) in the transport of PGE(2). METHODS: Biliary PGE(2) elimination was measured in liver perfusions in Wistar and MRP2-deficient TR(-) rats. Furthermore, transport experiments were performed in membrane vesicles from human MRP2-infected Spodoptera frugiperda 21 (Sf21) insect cells. RESULTS: The liver perfusions showed a 3.5 times higher percentage of undegraded [(3)H]PGE(2) in bile of Wistar rats in comparison with MRP2 deficient (TR(-)) rats (3.6% vs. 1.1%, respectively; P<0.05). MRP2-mediated transport of the model substrate [(3)H]DNP-SG was inhibited by PGE(2). Half maximal inhibition was achieved at a concentration of approximately 15 microM PGE(2). In addition, [(3)H]PGE(2) uptake in these vesicles was detected, and determined to be ATP dependent. CONCLUSION: MRP2 mediates the transport of PGE(2) and its breakdown products. The biliary excretion of PGE(2) via MRP2 may contribute to rapid elimination of the prostaglandin but might also serve to relay prostaglandin signalling to the biliary tree.     

耐多药相关蛋白在人非小细胞肺癌组织中的表达

目的　检测人非小细胞肺癌组织中耐多药相关蛋白（ＭＲＰ） 的表达,探讨其与瘤组织学类型、分化程度、临床分期及预后的关系。方法　采用免疫组化方法及逆转录聚合酶链反应（ＲＴＰＣＲ）技术,分别检测了９２ 份人非小细胞肺癌石蜡组织中ＭＲＰ的表达及１６ 份人非小细胞肺癌新鲜组织中ＭＲＰ基因的表达。结果　９２ 份人非小细胞肺癌组织中（ 鳞癌４３ 例,腺癌４９ 例）ＭＲＰ表达阳性检出率为５４％（５０／９２） ,１６ 份人非小细胞肺癌组织中ＭＲＰ基因表达阳性检出率为３１％ （５／１６）。ＭＲＰ在腺癌中的表达阳性率明显高于鳞癌（ Ｐ＜ ０－０５） ,ＭＲＰ表达与瘤分化程度、肿瘤大小及淋巴结转移无显著相关。ＭＲＰ阳性患者术后５ 年生存率为１６％ （８／５０）,ＭＲＰ 阴性患者术后５ 年生存率为５２％ （２２／４２） ,二者经统计学处理,差异有显著性（ Ｐ＜ ０－０５）。ＭＲＰ阳性患者术后５ 年生存率有随其瘤组织中该蛋白表达阳性程度的增加而降低之趋势。结论　非小细胞肺癌患者瘤组织中ＭＲＰ的表达与瘤组织学类型及预后明显相关。     

A novel ancestral splicing mutation in the multidrug resistance protein 2 gene causes Dubin-Johnson syndrome in Ashkenazi Jewish patients.

Dubin-Johnson syndrome (DJS) is an inherited disorder characterized by chronic conjugated hyperbilirubinemia due to the absence or dysfunction of the multidrug resistance protein 2 (MRP2). We previously identified two distinct ancestral mutations causing DJS in 22 unrelated Iranian and five unrelated Moroccan Jewish patients, respectively. In this study we identified and characterized the mutation causing DJS in Ashkenazi Jewish patients and assessed a possible founder effect. Sequencing of all 32 exons of the MRP2 gene identified a novel IVS8+4A-->G mutation in three unrelated homozygotes. Haplotype analysis using four intragenic dimorphisms disclosed a founder effect for the mutation. RT-PCR and real time PCR analysis of mRNA from one patient revealed three splice variants all leading to frameshifts and predicting premature termination codons. The main splice variant was a consequence of the use of a cryptic donor splice site inside exon 8. Liver biopsy in one patient revealed complete absence of MRP2 from the canalicular membrane of hepatocytes. In conclusion, our results provide strong evidence that an ancestral IVS8+4A-->G mutation causes DJS in Ashkenazi Jewish patients by abolishing normal splicing of intron 8 leading to aberrantly spliced products that predict truncation of MRP2.     

Portal vein tumor thrombus from colorectal cancer with no definite metastatic nodules in liver parenchyma

Portal vein tumor thrombus (PVTT) in hepatocellular carcinoma (HCC) is a common entity. In colorectal liver metastasis, microscopic tumor invasion into the intrahepatic portal vein is also usually observed, but the incidence of macroscopic tumor thrombus in the first branch and trunk of the portal vein is rare. Most reported cases of PVTT from colorectal cancer had concomitant metastatic nodules in liver parenchyma, and the PVTT was continuous with the liver nodule, like PVTT in HCC. We present a case of PVTT from colorectal cancer with no definite metastatic nodules in liver parenchyma. A 58-year old man underwent laparoscopic high anterior resection for rectosigmoid carcinoma accompanied by bulky tumor thrombus in the branch of the inferior mesenteric vein. Six months later, he received left lobectomy and left caudate resection for liver metastasis. The resected specimen demonstrated there was no metastatic nodule in liver parenchyma and that the left portal system was filled with the tumor thrombus. The patient is alive with no sign of recurrence 66 months after hepatectomy. Even if there is a macroscopic PVTT from colorectal cancer, a better prognosis may be expected when the tumor can be completely resected en-bloc by anatomic hepatectomy including PVTT.     

Octarepeat peptides of prion are essential for multidrug resistance in gastric cancer cells

OBJECTIVE: In previous studies cellular prion protein (PrPc) is confirmed to be involved in multidrug resistance (MDR) of gastric cancer. Although octarepeat peptides are important functional domains of PrPc and are closely related to the transport of Cu²⁺/Zn²⁺ and antioxidative function, the significance in MDR remains unknown. We aimed to investigate the role of octarepeat peptides in gastric cancer MDR. METHODS: Small interfering RNA (siRNA) against PrPc were transfected into adriamycin‐resistant gastric cancer cell lines to inhibit the expression of wild type PrPc, and then constructs encoding PrPc without octarepeat peptides and PrPc without the fifth repeat peptide were transfected, respectively, to establish the cell models. In vitro drug sensitivity, cell apoptosis, measurement of superoxide dismutase (SOD), glutathione peroxidase (GSH‐Px) and glutathione (GSH), as well as changes in glutathione S‐transferase (GST) were detected. RESULTS: In vitro drug sensitivity test showed that octarepeat peptides could modulate the drug resistance of gastric cancer cells, but the deletion of the fifth repeat peptide had no effect. Specifically, the anti‐apoptotic capacity of gastric cancer cells decreased significantly when the octarepeat peptides of PrPc was absent. Moreover, the activities of total SOD, Cu²⁺/Zn²⁺‐SOD, GSH‐Px, GSH, and GST detected in different stressing periods revealed that cells lacking octarepeat peptides of PrPc exhibited weakened responses to stress. However, absence of the fifth repeat peptide did not exert any effect on stress response. CONCLUSION: The octarepeat peptides of prion is responsible for MDR in gastric cancer cells while the fifth repeat peptide is not.     

Minimal expression of the proto-oncogene int-2 encoded protein in a series of colorectal carcinomas

BACKGROUND: Int-2 (fibroblast growth factor-3) is a gene that belongs to the fibroblast growth factor gene family. It has been implicated in the carcinogenesis of several types of cancer, including esophageal squamous cell carcinoma, breast, head, and neck and lung carcinomas; but no firm data on its biological activity regarding neoplasms arising from the glandular epithelia of the gastrointestinal tract exists. METHODS: In the present immunohistochemical study, we investigated the presence of int-2 encoded protein in a panel of 80 cases of colon carcinoma of various stages, grades and sizes. A sheep antihuman int-2 antibody was applied to paraffin-embedded tissue sections from the tumor samples. The percentage of int-2 immunostaining in the positively stained specimens was evaluated by image analysis. RESULTS: Int-2 was positively detected in only four tumors (i.e. 5% of the cases examined). All immunopositive cases were moderately differentiated tumors; the adjacent mucosa did not express int-2 protein. The relevant patients were male. CONCLUSION: These findings suggest that the role of int-2 in colorectal carcinogenesis is probably a limited one.     

Development of extended multidrug resistance in HL60 promyelocytic leukaemia cells

Summary. In an attempt to mimic clinical conditions for the treatment of leukaemia, the HL60 promyelocytic cell line was treated for 18 h with low, clinically relevant, levels of the anthracycline epirubicin and the Vinca alkaloid vinblastine. The resulting drug-resistant sublines not only expressed P-glycoprotein and the MDR phenotype but were also cross-resistant to chlorambucil, methotrexate but were also cross-resistant to chlorambucil, methotrexate and cisplatinum, and had increased resistance to radiation. Development of resistance was associatted with an aberrant differentiation phenotype with decreased expression of myeloid antigens and expression of glycophorin A. an antigen normally associated with erythroid differentiation. The ability of HL60 cells to terminally differentiate in response to all- trans -retinoic acid (vitamin A acid) was lost in the sublines. These results suggest that either a single novel mechanism is responsible for multiple drug resistance or the initial response to drug treatment is the co-induction of multiple mechanisms. These cells and the method by which they were generated therefore provide a clinically relevant model for the study of the initial events in the development of not only multidrug resistance but also the extended multiple drug resistance usually encountered in the treatment of leukaemia.