Acquisition of resistance to anti-cancer drugs is a significant obstacle to effective cancer treatment. Although several efforts have been made to overcome drug resistance in cancer cells, the detailed mechanisms have not been fully elucidated. Here, we investigated whether microRNAs (miRNAs) function as pivotal regulators in the acquisition of anti-cancer drug resistance to 5-fluorouracil (5-FU). A survey using a lentivirus library containing 572 precursor miRNAs revealed that five miRNAs promoted cell survival after 5-FU treatment in human hepatocellular carcinoma Hep3B cells. Among the five different clones, the clone expressing miR-200a-3p (Hep3B-miR-200a-3p) was further characterized as a 5-FU-resistant cell line. The cell viability and growth rate of Hep3B-miR-200a-3p cells were higher than those of control cells after 5-FU treatment. Ectopic expression of a miR-200a-3p mimic increased, while inhibition of miR-200a-3p downregulated, cell viability in response to 5-FU, doxorubicin, and CDDP (cisplatin). We also showed that dual-specificity phosphatase 6 (DUSP6) is a novel target of miR-200a-3p and regulates resistance to 5-FU. Ectopic expression of DUSP6 mitigated the pro-survival effects of miR-200a-3p. Taken together, these results lead us to propose that miR-200a-3p enhances anti-cancer drug resistance by decreasing DUSP6 expression.
Carcinoma, Hepatocellular ; Cell Line ; Cell Survival ; Clone Cells ; Doxorubicin ; Drug Resistance ; Dual Specificity Phosphatase 6* ; Dual-Specificity Phosphatases* ; Ectopic Gene Expression ; Fluorouracil* ; Humans ; Lentivirus ; MicroRNAs

The mitogen-activated protein kinases (MAPKs) are key regulators of cell growth and survival in physiological and pathological processes. Aberrant MAPK signaling plays a critical role in the development and progression of human cancer, as well as in determining responses to cancer treatment. The MAPK phosphatases (MKPs), also known as dual-specificity phosphatases (DUSPs), are a family of proteins that function as major negative regulators of MAPK activities in mammalian cells. Studies using mice deficient in specific MKPs including MKP1/DUSP1, PAC-1/DUSP2, MKP2/DUSP4, MKP5/DUSP10 and MKP7/DUSP16 demonstrated that these molecules are important not only for both innate and adaptive immune responses, but also for metabolic homeostasis. In addition, the consequences of the gain or loss of function of the MKPs in normal and malignant tissues have highlighted the importance of these phosphatases in the pathogenesis of cancers. The involvement of the MKPs in resistance to cancer therapy has also gained prominence, making the MKPs a potential target for anti-cancer therapy. This review will summarize the current knowledge of the MKPs in cancer development, progression and treatment outcomes.
Animals ; Dual-Specificity Phosphatases ; Homeostasis ; Humans ; Mice ; Mitogen-Activated Protein Kinase Phosphatases* ; Mitogen-Activated Protein Kinases ; Pathologic Processes ; Phosphoric Monoester Hydrolases

OBJECTIVE: To assess the association of single nucleotide polymorphisms (SNPs) of dual specificity phosphatase 9 (DUSP9) gene rs5945326 locus with gestational diabetes mellitus (GDM). METHODS: Genotypes for the rs5945326 locus were determined for 206 pregnant women with GDM (GDM group) and 189 unaffected pregnant women (control group). Allelic and genotypic frequencies of the GDM and control groups were compared. For individuals with various genotypes, the level of blood glucose, serum lipids, and body mass index (BMI) were also compared. RESULTS: The frequencies of AA, AG and GG genotypes for the GDM group were 32.2%, 52.2% and 15.6%, respectively, and 41.2%, 43.9% and 15.0%, for the control group, respectively. No significant difference was detected in the distribution of above genotypes between the two groups (chi-square=3.601, P=0.165). The frequencies of alleles A and G were 58.3% and 41.7% in the GDM group, and 63.1% and 36.9% in the control group, respectively. No significant difference was detected between the two groups too (chi-square=1.894, P=0.188). The high density lipoprotein (HDL) levels of the GG genotype [(2.34×0.61) mmol/L] was significantly higher than that of the AG+AA genotype [(2.06×0.56) mmol/L] (t=2.993, P=0.003). No significant difference was detected in other clinical indexes between the two groups (P> 0.05). CONCLUSION The SNP rs5945326 in DUSP9 gene may be not associated with the risk of GDM. However, there are correlated with HDL levels.
Alleles ; Diabetes, Gestational ; genetics ; Dual-Specificity Phosphatases ; genetics ; Female ; Gene Frequency ; Genotype ; Humans ; Mitogen-Activated Protein Kinase Phosphatases ; genetics ; Polymorphism, Single Nucleotide ; Pregnancy

BACKGROUND: Lung cancer is the leading cause of cancer-related death worldwide, for which smoking is considered as the primary risk factor. The present study was conducted to determine whether genetic alterations induced by radon exposure are associated with the susceptible risk of lung cancer in never smokers. METHODS: To accurately identify mutations within individual tumors, next generation sequencing was conduct for 19 pairs of lung cancer tissue. The associations of germline and somatic variations with radon exposure were visualized using OncoPrint and heatmap graphs. Bioinformatic analysis was performed using various tools. RESULTS: Alterations in several genes were implicated in lung cancer resulting from exposure to radon indoors, namely those in epidermal growth factor receptor (EGFR), tumor protein p53 (TP53), NK2 homeobox 1 (NKX2.1), phosphatase and tensin homolog (PTEN), chromodomain helicase DNA binding protein 7 (CHD7), discoidin domain receptor tyrosine kinase 2 (DDR2), lysine methyltransferase 2C (MLL3), chromodomain helicase DNA binding protein 5 (CHD5), FAT atypical cadherin 1 (FAT1), and dual specificity phosphatase 27 (putative) (DUSP27). CONCLUSIONS: While these genes might regulate the carcinogenic pathways of radioactivity, further analysis is needed to determine whether the genes are indeed completely responsible for causing lung cancer in never smokers exposed to residential radon.
Cadherins ; Computational Biology ; DNA-Binding Proteins ; Dual-Specificity Phosphatases ; Genes, Homeobox ; Lung Neoplasms* ; Lung* ; Lysine ; Radioactivity ; Radon* ; Receptor, Epidermal Growth Factor ; Risk Factors ; Smoke ; Smoking ; TYK2 Kinase

PURPOSE: The dual-specificity phosphatase PTEN/ MMAC1/TEP1 has recently been identified as the tumor suppressor gene most frequently mutated and/or deleted in human tumors. However, PTEN mutations have rarely been detected in sporadic thyroid cancers. Therefore, this study investigated the PTEN expression of thyroid cancer and the relationship between PTEN, clinical status and other biologic factors such as HER-2/neu and p53. MATERIALS AND METHODS: The study samples consisted of 62 thyroid cancer specimens and 24 benign thyroid tumor specimens from patients who were operated on the Department of Surgery, Uijongbu St. Mary's hospital during the 5 years from January 1995 until January 2000. All tumors were studied by immunohistochemical staining using monoclonal antibodies against PTEN, HER-2/neu and p53. The results were analyzed statistically. RESULTS: PTEN protein was found to be under-expressed more frequently in thyroid cancers (29%) than in benign thyroid tumors (4.2%). The reduction in PTEN expression in thyroid cancers was not significantly related with the recorded clinical factors such as size, age, lymph node metastasis and p53, except for HER-2 which was found to be significantly related (p=0.001). HER-2 over- expression was noted in thyroid cancer (83.8%) more frequently than in benign tumors (16.7%). CONCLUSION: This study has demonstrated that the under-expression of PTEN protein and the over-expression of HER-2 protein may play a role in the carcinogenesis and development of thyroid cancer.
Antibodies, Monoclonal ; Biological Factors ; Carcinogenesis ; Dual-Specificity Phosphatases ; Genes, p53 ; Genes, Tumor Suppressor ; Humans ; Lymph Nodes ; Neoplasm Metastasis ; PTEN Phosphohydrolase ; Thyroid Gland* ; Thyroid Neoplasms

BACKGROUNDPreviously, we reported that dual-specificity phosphatase 1 (DUSP1) was differentially expressed in endometrioid adenocarcinoma (EEA). However, the role of DUSP1 in EEA progression and the relationship between DUSP1 and medroxyprogesterone (MPA) are still unclear.

METHODSThe expression of DUSP1 in EEA specimens was detected by immunohistochemical analysis. The effect of DUSP1 on cell proliferation was analyzed by Cell Counting Kit 8 and colony formation assay, and cell migration was analyzed by transwell assay. MPA-induced DUSP1 expression in EEA cells was measured by Western blot.

RESULTSDUSP1 expression was deficient in advanced International Federation of Gynecology and Obstetrics stage, high-grade and myometrial invasive EEA. In EEA cell lines (Hec1A, Hec1B, RL952, and Ishikawa), the DUSP1 expression was substantially higher in Ishikawa cells than in other cell lines (P < 0.05). Knockdown of DUSP1 promoted Ishikawa cells proliferation, migration, and activation of mitogen-activated protein kinases/extracellular signal-regulated kinase (MAPK/Erk) pathway. MPA-induced DUSP1 expression and inhibited MAPK/Erk pathway in Ishikawa cells.

CONCLUSIONSOur data suggest that DUSP1 deficiency promotes EEA progression via MAPK/Erk pathway, which may be reversed by MPA, suggesting that DUSP1 may serve as a potential therapeutic target for the treatment of EEA.

Carcinoma, Endometrioid ; metabolism ; Cell Culture Techniques ; Cell Proliferation ; genetics ; physiology ; Dual-Specificity Phosphatases ; genetics ; metabolism ; Extracellular Signal-Regulated MAP Kinases ; metabolism ; Female ; Humans ; Mitogen-Activated Protein Kinases ; metabolism

BACKGROUND: Toll-like receptors (TLRs) are well-known pattern recognition receptors. Among the 13 TLRs, TLR2 is the most known receptor for immune response. It activates mitogen-activated protein kinases (MAPKs), which are counterbalanced by MAPK phosphatases [MKPs or dual-specificity phosphatases (DUSPs)]. However, the regulatory mechanism of DUSPs is still unclear. In this study, the effect of a TLR2 ligand (TLR2L, Pam3CSK4) on DUSP4 expression in Raw264.7 cells was demonstrated. METHODS: A Raw264.7 mouse macrophage cell line was cultured in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum and 1% antibiotics (100 U/mL penicillin and 100 g/mL streptomycin) at 37degrees C in 5% CO2. TLR2L (Pam3CSK4)-mediated DUSP4 expressions were confirmed with RT-PCR and western blot analysis. In addition, the detection of reactive oxygen species (ROS) was measured with lucigenin assay. RESULTS: Pam3CSK4 induced the expression of DUSP1, 2, 4, 5 and 16. The DUSP4 expression was also increased by TLR4 and 9 agonists (lipopolysaccharide and CpG ODN, respectively). Pam3CSK4 also induced ERK1/2 phosphorylation and ROS production, and the Pam3CSK4-induced DUSP4 expression was decreased by ERK1/2 (U0126) and ROS (DPI) inhibitors. U0126 suppressed the ROS production by Pam3CSK4. CONCLUSION: Pam3CSK4-mediated DUSP4 expression is regulated by ERK1/2 and ROS. This finding suggests the physiological importance of DUSP4 in TLR2-mediated immune response.
Acridines ; Animals ; Anti-Bacterial Agents ; Blotting, Western ; Butadienes ; Cell Line ; Dual-Specificity Phosphatases ; Macrophages ; Mice ; Mitogen-Activated Protein Kinase Phosphatases ; Mitogen-Activated Protein Kinases ; Nitriles ; Penicillins ; Phosphorylation ; Phosphotransferases ; Reactive Oxygen Species ; Receptors, Pattern Recognition ; Toll-Like Receptors

PURPOSE: Gastric cancer is one of the most prevalent cancers worldwide. 5-fluorouracil (5-FU) and cisplatin are the most commonly used drugs for the treatment of gastric cancer. However, a significant number of tumors often fail to respond to chemotherapy. MATERIALS AND METHODS: To better understand the molecular mechanisms underlying drug resistance in gastric cancer the gene expression in gastric cancer cells, which were either sensitive or resistant to 5-FU and cisplatin, were examined using cDNA microarray analysis. To confirm the differential gene expression, as determined using the microarray, semiquantitative RT-PCR was performed on a subset of differentially expressed cDNAs. RESULTS: 69 and 45 genes, which were either up-regulated (9 and 22 genes) or down-regulated (60 and 25 genes), were identified in 5-FU- and cisplatin-resistant cells, respectively. Several genes, such as adaptor-related protein complex 1 and baculoviral IAP repeat-containing 3, were up-regulated in both drug-resistant cell types. Several genes, such as the ras homolog gene family, tropomyosin, tumor rejection antigen, protein disulfide isomerase-related protein, melanocortin 1 receptor, defensin, cyclophilin B, dual specificity phosphatase 8 and hepatocyte nuclear factor 3, were down-regulated in both drug-resistant cell types. CONCLUSION: These findings show that cDNA microarray analysis can be used to obtain gene expression profiles that reflect the effect of anticancer drugs on gastric cancer cells. Such data may lead to the assigning of signature expression profiles of drug-resistant tumors, which may help predict responses to drugs and assist in the design of tailored therapeutic regimens to overcome drug resistance.
Adaptor Protein Complex 1 ; Cisplatin* ; Cyclophilins ; DNA, Complementary* ; Drug Resistance ; Drug Therapy ; Dual-Specificity Phosphatases ; Fluorouracil* ; Gene Expression* ; Hepatocytes ; Humans ; Oligonucleotide Array Sequence Analysis* ; Receptor, Melanocortin, Type 1 ; Stomach Neoplasms* ; Transcriptome ; Tropomyosin

OBJECTIVESTo explore the relationships between the peripheral blood levels of CD61, CD63, PAC-1 and the incidence of acute rejection and tubular necrosis after renal transplantation, and recovery of the graft function.

METHODSThe peripheral blood levels of CD61, CD63, and PAC-1 of 86 patients with uremia in different stages before and after transplantations were analyzed by flow cytometry. The patients were divided into three groups: (1) twenty-nine patients with normal grafts function, (2) hirty with acute rejection and (3) twenty-seven with acute tubular necrosis. The patients with acute rejection were randomly divided into treatment group with anticoagulants and cntrol group.

RESULTSThe peripheral blood levels of CD61, CD63 and PAC-1 significantly increased (P < 0.05) in the patients with acute rejection, in comparison with those with normal grafts function and those with acute tubular necrosis. The peripheral blood levels of CD61, CD63 and PAC-1 in patients with acute rejection in anticoagulants therapy was lower, recovery time of the grafts function was shorter, one-year survival rates of patients and grafts were higher, as compared with those of controls.

CONCLUSIONSThe patients with acute rejection have significantly high peripheral blood levels of CD61, CD63 and PAC-1 before transplantation, however, these values in patients with acute tubular necrosis are not high, this suggesting that acute rejection might relate to platelet activation, while acute tubular necrosis might not relate to it. After anticoagulants therapy in patients with acute rejection, the grafts function might recover faster and their one-year survival rates and grafts might be higher in those with CD61, CD63 and PAC-1 decreasing remarkably.

Adult ; Aged ; Antigens, CD ; blood ; Dual Specificity Phosphatase 2 ; Female ; Graft Rejection ; Humans ; Integrin beta3 ; blood ; Kidney ; physiopathology ; Kidney Transplantation ; Male ; Middle Aged ; Platelet Activation ; Platelet Membrane Glycoproteins ; Protein Phosphatase 2 ; Protein Tyrosine Phosphatases ; blood ; Tetraspanin 30

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