The occurrence and development of acute myeloid leukemia (AML) is not only related to gene mutations, but also influenced by abnormal epigenetic regulation, in which DNA methylation is one of the most important mechanisms. Abnormal DNA methylation may lead to the activation of oncogene and the inactivation of tumor suppressor gene, resulting in the occurrence of leukemia. The mutations of DNA methylation enzymes associated with AML may have certain characteristics. The AML with recurrent cytogenetic abnormalities is also related to abnormal methylation. Some fusion genes can alter DNA methylation status to participate in the pathogenesis of leukemia. In addition, chemotherapy drug resistance in patients with AML is associated with the change of gene methylation status. Considering the reversibility of the epigenetic modification, targeted methylation therapy has become a hotspot of AML research.
DNA Methylation ; drug effects ; genetics ; physiology ; DNA Modification Methylases ; genetics ; physiology ; Drug Resistance, Neoplasm ; genetics ; Epigenesis, Genetic ; genetics ; physiology ; Humans ; Leukemia, Myeloid, Acute ; etiology ; genetics ; pathology ; Mutation ; genetics

OBJECTIVETo analyze the distribution and significance of occludin mRNA expression in human gastric cancer, as well as its relationship with gastric cancer pathology and multidrug resistance (MDR) in vivo.

METHODSIn situ hybridization (ISH) technique was used to evaluate the expression of occludin mRNA in 42 gastric carcinoma specimens obtained by surgery and 23 relatively normal gastric mucosa obtained by gastric endoscopy. All specimens had been stored in cryostatic section.

RESULTSOccludin mRNA was found positive in the cytoplasm of gastric glandulous epithelia as blue particles with intensive stain in 14 of 42 gastric carcinomas (33.3%), 23 of 42 paracancerous gastric tissues (54.8%), 14 of 23 relatively normal gastric tissues (60.9%), 9 of 16 well differentiated carcinomas (56.3%), 4 of 14 moderately differentiated carcinomas (28.6%), 1 of 10 poorly differentiated carcinomas (10.0%) and none of 2 mucosal carcinomas. There were significant differences in occludin mRNA positive rate between relatively normal gastric tissue and gastric cancer as well as between paracancerous gastric tissue and gastric cancer. The expression of occludin mRNA in moderately and poorly differentiated groups was gradually reduced when compared with well differentiated group, which suggests that there be a significant correlation between tumor differentiation and the expression of occludin mRNA. Furthermore, the positive signals of occludin mRNA distributed extensively in the cytoplasm of SGC7901/VCR cell, being vincristine resistant, derived from parental gastric cell line SGC7901. The positive signals of SGC7901/VCR were stronger than those of SGC7901 cells.

CONCLUSIONOccludin mRNA, being mainly located in epithelial cells and its expression correlated with tumor differentiation, may be involved in the development of multi-drug resistance in gastric cancer.

Drug Resistance, Multiple ; physiology ; Drug Resistance, Neoplasm ; physiology ; Humans ; In Situ Hybridization ; Membrane Proteins ; genetics ; metabolism ; Occludin ; RNA, Messenger ; metabolism ; Stomach Neoplasms ; metabolism ; Tight Junctions ; metabolism

microRNAs (miRNAs) are a class of non-coding RNAs that function as endogenous triggers of the RNA interference pathway. Studies have shown that thousands of human protein-coding genes are regulated by miRNAs, indicating that miRNAs are master regulators of many important biological processes, such as cancer development. miRNAs frequently have deregulated expression in many types of human cancers, and play critical roles in tumorigenesis, which functions either as tumor suppressors or as oncogenes. Recent studies have shown that miRNAs are highly related with cancer progression, including initiating, growth, apoptosis, invasion, and metastasis. Furthermore, miRNAs are shown to be responsible for the cancer-related inflammation, anti-cancer drug resistance, and regulation of cancer stem cells. Therefore, miRNAs have generated great interest as a novel strategy in cancer diagnosis and therapy. Here we review the versatile roles of miRNAs in cancers and their potential applications for diagnosis, prognosis, and treatment as biomarkers.
Animals ; Biomarkers, Tumor ; Drug Resistance, Neoplasm ; genetics ; Epithelial-Mesenchymal Transition ; genetics ; Gene Expression Regulation, Neoplastic ; Gene Knockdown Techniques ; Genes, Tumor Suppressor ; Humans ; Inflammation ; genetics ; MicroRNAs ; genetics ; physiology ; Neoplasm Invasiveness ; genetics ; Neoplasm Metastasis ; genetics ; Neoplastic Stem Cells ; metabolism ; Oncogenes ; genetics

OBJECTIVETo investigate the correlation of glucosylceramide synthase (GCS) gene and multidrug resistance 1 (MDR1) gene in inducing multidrug resistance in human multidrug-resistant K562/A02 cell line, and search for a novel strategy for reversing multidrug resistance of leukemia cells.

METHODSThe expression levels of GCS and MDR1 mRNA in K562 and K562/A02 cells were assayed by RT-PCR. siRNAs targeting the GCS and MDR1 gene were transfected into K562/A02 cells with liposome, respectively. The differential expression of GCS and MDR1 mRNAs, as well as their correlation, were detected by RT-PCR and real time quantitative-PCR(QPCR).

RESULTSThe expression level of GCS and MDR1 mRNA was dramatically lower in drug-sensitive K562 cells compared with the K562/A02 cells. The GCS mRNA was inhibited by 73%(59%-82%) and MDR1 mRNA expression was down regulated by 67% (38%-82%) in K562/A02 cells after being transfected with GCS siRNA. The expression level of MDR1 mRNA was inhibited by 81%(63%-91%) and GCS mRNA expression had no apparent change in K562/A02 cells treated with MDR1 small interference RNA(siRNA).

CONCLUSIONPositive correlation was detected between the expression of GCS and MDR1 mRNA in K562/A02 cells and MDR1 mRNA expression was down regulated after silencing the GCS gene expression.

ATP-Binding Cassette, Sub-Family B, Member 1 ; genetics ; Cell Line, Tumor ; Drug Resistance, Multiple ; genetics ; Drug Resistance, Neoplasm ; genetics ; Glucosyltransferases ; genetics ; Humans ; RNA, Messenger ; genetics ; RNA, Small Interfering ; genetics ; physiology ; Reverse Transcriptase Polymerase Chain Reaction

OBJECTIVETo study the effect of human calcyclin binding protein (CacyBP) encoding gene on the development of multiple drug resistance in gastric cancer.

METHODShCacyBP sense nucleic acid eukaryotic expression vector (pcDNA3.1/hCacyBP +) was constructed and then transfected steadily into the gastric cancer drug sensitive cell (SGC7901) mediated by lipofectamine ( trade mark ) 2000. RT-PCR was used to measure the CacyBP mRNA expression level. MTT was used to measure the adriamycin (ADR) drug sensitivity of SGC7901 and SGC7901 after transfection. FCM was used to measure the average ADR accumulation concentration and cell cycle of SGC7901 and SGC7901 after transfection.

RESULTSThe hCacyBP mRNA expression level of SGC7901 transfected with pcDNA3.1/hCacyBP + was higher than SGC7901 transfected with pcDNA3.1 or SGC7901, with the higher survival rate in the former. The average ADR accumulation concentration in SGC7901 and SGC7901 transfected with pcDNA3.1 or pcDNA3.1/hCacyBP + was 5.64, 5.49 and 5.17, respectively. The G(1) phase cell proportion of SGC7901 transfected with pcDNA3.1/hCacyBP + or pcDNA3.1 was reduced slightly but G(2) and S phases increased slightly as compared with SGC7901.

CONCLUSIONCalcyclin binding protein may play a certain role in gastric cancer drug resistance.

Base Sequence ; Calcium-Binding Proteins ; genetics ; physiology ; DNA, Complementary ; analysis ; Drug Resistance, Multiple ; physiology ; Drug Resistance, Neoplasm ; physiology ; Drug Screening Assays, Antitumor ; Gene Transfer Techniques ; Humans ; Molecular Sequence Data ; Plant Lectins ; Stomach Neoplasms ; pathology ; Tumor Cells, Cultured

Acute lymphoblastic leukemia (ALL) is a malignant clonal disease, its treatment methods include chemotherapy, hematopoietic stem cell transplantation, immunotherapy and molecular targeted therapy. Clinically, ALL patients need to get complete remission through chemotherapy, and then choose the other treatment according to the patient's condition. But the drug resistance has been a biggest obstacle in treatment of ALL. There are many research reports about drug-resistant of ALL at present. In this review, the classic drug resistance mechanisms, such as membrane transporter, gene modifications and some newly finding mechanisms including such as bone marrow microenvironment and Micro RNA and so on are summarized.
Bone Marrow ; physiology ; Cellular Microenvironment ; Drug Resistance, Neoplasm ; Humans ; Membrane Transport Proteins ; physiology ; MicroRNAs ; genetics ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; drug therapy

OBJECTIVETo explore the role of X-linked inhibitor of apoptosis protein (XIAP) in the fibronectin (Fn)-adhesion mediated drug resistance of HL-60 cells.

METHODSCulture plates were coated with Fn and bovine serum albumin (BSA) (as control), respectively. Colorimetric CCK-8 assay was used to determine the effects of Fn on the cytotoxicity of DNR to HL-60 cells. Intracellular DNR accumulation was assayed with flow cytometry. Reverse transcription-PCR and Western blot were used to examine the mRNA expression and XIAP, bcl-2, MRP and mdr1 proteins, respectively. HL-60 cells were added to Fn coated Culture plates. The fully phosphorothioate antisense oligonucleotide (AS-ODNs) and the control ODNs of XIAP were delivered into HL-60 cells in the form of liposome-ODN complexes. IC(50) was calculated by linear regression of survival percent versus drug concentration.

RESULTSHL-60 cells adhered to Fn-coated plates had a significant survival advantage over those grown on BSA coated plates and in suspension when exposed to DNR, the IC(50) of Fn group being significantly higher than that of BSA group and suspension group (0.526 micromol/L vs 0.132 micromol/L, 0.123 micromol/L, respectively, P < 0.05). XIAP was up-regulated significantly in Fn group compared with BSA group and suspension group (P < 0.05), whereas there was no difference in the expressions of bcl-2, MRP and mdr1 among the three groups (P > 0.05). The intracellular concentration of DNR in Fn-adhered HL-60 cells was similar to that in BSA group and suspension group (P < 0.05). AS-ODNs of XIAP down-regulated the XIAP expression in Fn-adhered HL-60 cells. In addition, AS-ODNs sensitized HL-60 cells to the cytotoxic effects of DNR.

CONCLUSIONThe increased XIAP protein level contributes to the drug resistance induced by adhesion to Fn. AS-ODNs of XIAP might reverse the drug resistance.

ATP-Binding Cassette, Sub-Family B, Member 1 ; genetics ; metabolism ; Cell Adhesion ; Daunorubicin ; pharmacology ; Drug Resistance, Multiple ; genetics ; physiology ; Drug Resistance, Neoplasm ; genetics ; physiology ; Fibronectins ; HL-60 Cells ; Humans ; Multidrug Resistance-Associated Proteins ; genetics ; metabolism ; Oligonucleotides, Antisense ; genetics ; RNA, Messenger ; genetics ; Transfection ; X-Linked Inhibitor of Apoptosis Protein ; genetics ; metabolism ; physiology

OBJECTIVETo investigate the relationship between aldose reductase like protein (ARL-1) gene overexpressed in HCC cells and drug-resistance of the cell to drugs containing carbonyl group.

METHODSTo establish ARL-1 stable expression positive cell line, eukaryotic expression vectors containing ARL-1 gene cDNA were transfected into Hep cell mediated by lipofect AMINE. The positive monoclones were determined by PCR and RT-PCR, respectively. Then MTT assay was used to study the drug resistance ability of the cells to drugs containing carbonyl after incubating three days with those drugs.

RESULTSAfter ARL-1 gene transfection mediated by lipofect AMINE, one positive monoclonal cell overexpressing ARL-1 gene was selected. Compared with the control cell group, drug resistance ability of the positive cells to ADM and MMC which contain carbonyl group increased 2.3 and 3.17 fold, respectively (t=6.39, P=0.016 in ADM group and t=30.06, P=0.001 in MMC group). In the same time, drug resistance ability to 5-FU which has no carbonyl group had no statistical difference between positive monoclonal cell group and control cell group (t=0.684, P=0.531).

CONCLUSIONSThe Hep ARL-1 positive cell line with stable expression of ARL-1 gene has been established successfully and the up-regulation of ARL-1 gene may plays an important role in drug resistance of the cells to anticancer drugs containing carbonyl group.

Aldehyde Reductase ; genetics ; metabolism ; Antineoplastic Agents ; pharmacology ; Doxorubicin ; pharmacology ; Drug Resistance, Neoplasm ; genetics ; physiology ; Fluorouracil ; pharmacology ; Humans ; Inhibitory Concentration 50 ; Mitomycin ; pharmacology ; Transfection ; Tumor Cells, Cultured ; drug effects

A key issue in the treatment of acute leukemia is the development of resistance to chemotherapeutic drugs. Several mechanisms may account for this phenomenon, including failure of the cell to undergo apoptosis in response to chemotherapy, or failure of the drug to reach and/or affect its intracellular target. This review focuses on the latter mechanisms, and on intracellular drug transport resistance mechanisms in particular. Expression of the ATP-binding cassette (ABC) transporter P-glycoprotein (P-gp) has generally been reported to correlate with prognosis in acute myeloid leukemia (AML). Additionally, of more controversial, expression of the ABC transporter multidrug resistance protein (MRP) and the vault-transporter lung resistance protein (LRP) have been correlated with the outcome in AML.
ATP Binding Cassette Transporter, Sub-Family B ; physiology ; ATP-Binding Cassette, Sub-Family B, Member 1 ; physiology ; Drug Resistance, Multiple ; genetics ; Humans ; Leukemia, Myeloid, Acute ; drug therapy ; genetics ; Neoplasm Proteins ; physiology ; Vault Ribonucleoprotein Particles ; physiology

OBJECTIVETo investigate the role of mitogen activated protein kinase phosphatase-1 (MKP-1) in mediating acquired multidrug resistance in pancreatic adenocarcinoma cell line SW1990/Fu.

METHODSTo detect MKP-1 mRNA expression, Northern blot analysis was carried out in well established drug resistant pancreatic adenocarcinoma cell line SW1990/Fu, SW1990 and MiaPaCa-2 cell lines. To further elucidate the exact role of MKP-1, Western blot hybridization was performed in these three cell lines.

RESULTSNorthern blot analysis of total RNA isolated from SW1990/Fu, SW1990 and MiaPaCa-2 cell lines revealed the presence of the 2400 bp MKP-1 transcript 7 at relatively high levels in pancreatic cancer cell lines SW1990 and MiaPaCa-2. In the SW1990/Fu, the MKP-1 transcript was detectable at very low level. Densitometric analysis with normalization to 7S indicated that MKP-1 mRNA expression level was significantly decreased in SW1990/Fu in comparison with the parental and MiaPaCa-2 cell lines. MKP-1 protein expression level in SW1990/Fu detected by Western blot was coincident with mRNA level.

CONCLUSIONSMKP-1 may be involved in acquired multidrug resistance in pancreatic adenocarcinoma, and we could hypothesized that alterations of intra-cellular transduction signal system acts as an important role in multidrug resistance of tumor cells.

Adenocarcinoma ; drug therapy ; enzymology ; pathology ; Blotting, Northern ; Blotting, Western ; Cell Cycle Proteins ; biosynthesis ; genetics ; physiology ; Cell Line, Tumor ; Down-Regulation ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; Dual Specificity Phosphatase 1 ; Humans ; Immediate-Early Proteins ; biosynthesis ; genetics ; physiology ; Pancreatic Neoplasms ; drug therapy ; enzymology ; pathology ; Phosphoprotein Phosphatases ; biosynthesis ; genetics ; physiology ; Protein Phosphatase 1 ; Protein Tyrosine Phosphatases ; biosynthesis ; genetics ; physiology ; RNA, Messenger ; genetics