Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.48 (transcriptase)
9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The dissemination of cancer cells is a prerequisite in the development of micrometastases and solid metastases. Our previous examinations of these cells were based on immunocytological staining of tumor-associated antigens and cytokeratins. We have now developed a highly sensitive and specific detection method based on a nested reverse-transcriptase-polymerase-chain reaction (RT-PCR) of cytokeratin-20 (CK-20) mRNA. Using this method, we examined the bone marrow of 57 patients with colorectal cancer and detected increasing numbers of CK-20-positive samples, depending on the UICC stage. Some 35% of all bone-marrow samples tested positive for CK-20: none were found in colorectal cancer stage 1, 24% were in stage II, 31% in stage III and 71% in stage IV. Investigation of bone-marrow specimens of patients with pancreatic cancer showed that 4 out of 11 patients were positive for CK-20 mRNA. To confirm that sample positivity for CK-20 expression was due to disseminated tumor cells, we examined bone marrow from a control group (n = 16) without apparent carcinoma. In this group, 15 out of 16 donors were CK-20-negative, while one donor with familial adenomatous polyposis showed a CK-20-specific signal.
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PMID:The detection of disseminated tumor cells in bone marrow from colorectal-cancer patients by a cytokeratin-20-specific nested reverse-transcriptase-polymerase-chain reaction is related to the stage of disease. 879 68

The gastrointestinal peptides gastrin and cholecystokinin (CCK) stimulate growth of human pancreatic cancer through a CCK-B/gastrin- like receptor. In the present study we evaluated whether growth of human pancreatic cancer is endogenously regulated by gastrin. Immunohistomical examination of BxPC-3 cells and tumor xenografts revealed specifc gastrin immunoreactivity. Gastrin was detected by radioimmunoassay in pancreatic cancer cell extracts and in pancreatic cancer cell extracts and in the growth media. With use of reverse-transcriptase polymerase chain reaction gastrin gene expression was detected in both cultured BxPC-3 cancer cells and transplanted tumors, as well as seven addition human pancreatic cancer cell lines. Growth of BxPC-3 human pancreatic cancer cell in serum-free medium was inhibited by the addition of the CCK-B/gastrin receptor antagonist L-365,260, and gastrin treatment reversed the inhibitory effect of the antagonist. A selective gastrin antibody (Ab repressed growth of BxPC-3 cells. Gastrin immunoreactivity was detected in fresh human pancreatic cancer specimens but not in normal human pancreatic tissue. These data provide the first evidence that growth of a human pancreatic cancer is tonically stimulated by the autocrine production of gastrin. Evidence for the ubiquity of this system was provided by the detection of gastrin gene expression in multiple human pancreatic cancer cell lines and detection of gastrin in cell lines and fresh pancreatic tumors.
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PMID:Gastrin regulates growth of human pancreatic cancer in a tonic and autocrine fashion. 892 9

Reverse transcriptase-polymerase chain reaction (RT-PCR) targeted at keratin 19 mRNA was applied to detect circulating cancer cells in the peripheral and portal blood of pancreatic and gastric cancer patients. Keratin 19 mRNA expression was studied by RT-PCR in cancer tissues (12 pancreatic and 15 gastric cancers) and in peripheral and/or portal blood samples from patients with pancreatic cancer (stage I, n = 5; stage II, n = 1; stage III, n = 15; stage IV, n = 19), gastric cancer (stage la,b, n = 28; stage II, n = 9; stage IIIa,b, n = 5; stage IVa,b, n = 7) and benign pancreatic diseases (n = 7). Peripheral blood samples from 50 healthy volunteers served as controls. RT-PCR was conducted in duplicate in each sample, and only samples showing keratin 19 transcript in both determinations were considered as being positive. All the pancreatic and gastric cancers, but none of the control blood samples, were found to be positive. Dilution study using pancreatic cancer cells serially mixed against peripheral blood showed that detection sensitivity was more than one cancer cell in 10(6) peripheral blood mononuclear cells. In pancreatic cancer patients, RT-PCR analysis of the portal blood samples gave positive results in one stage III and one stage IV patient, and that of peripheral blood samples gave positive results in 2 stage IV patients. No positive results were obtained in any of the blood samples from gastric cancer patients. Our results indicate that incidence of circulating cancer cells is unexpectedly very low even in advanced pancreatic and gastric cancer patients.
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PMID:Detection of pancreatic and gastric cancer cells in peripheral and portal blood by amplification of keratin 19 mRNA with reverse transcriptase-polymerase chain reaction. 924 82

Differentially expressed genes between normal and cancer tissues of the pancreas were investigated using differential display. Consequently, we identified a fragment cDNA that was expressed in the normal tissue but was rarely expressed in the cancer tissue. This cDNA was screened in cDNA library prepared from the normal pancreatic tissue by rapid amplification of cDNA ends (5'RACE). 859 bp of cDNA was cloned and sequenced, and the inferred amino acid sequence was found to encode a G protein gamma subunit with 98% homology to cow G protein gamma 7 and complete homology to human G protein gamma 7. The decreased expression of the G protein gamma 7 was confirmed by Northern blot assay in twelve pancreatic malignancies which included nine duct cell carcinomas, two cystoadenocarcinomas and one blastoma. Reverse transcriptase (RT)-polymerase chain reaction (PCR) assay showed no expression of G protein gamma 7 in five of six pancreatic carcinoma cell lines and two pancreatic cancer tissues. Immunohistochemical analysis also displayed positive staining in the normal tissue but no staining in the cancer tissue. The findings demonstrated that the reduced or suppressed expression of human G-protein gamma 7 may play an important role in pancreatic carcinogenesis.
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PMID:Identification and cloning of human G-protein gamma 7, down-regulated in pancreatic cancer. 960 93

Members of the TGF-beta superfamily of cytokines have been implicated in pancreatic cancer, pancreatitis and in regulation and differentiation of pancreatic endocrine and exocrine cells. Different TGF-beta members signal through phosphorylation of different signal transduction proteins, which eventually form oligomers with SMAD 4 and translocate to the nucleus. Reverse transcriptase-polymerase chain reaction showed that SMADs 1, 2 and 4 are expressed in pancreatic islets. Immunostaining revealed that SMAD 1 and 4 predominantly were expressed by islet insulin and glucagon cells. Since SMAD 1 is known to transduce signals from receptors binding bone morphogenetic protein (BMP) these results indicate a previously unknown role of BMP-like ligands in islet function.
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PMID:Expression of SMAD signal transduction molecules in the pancreas. 1168 56

The 5-lipoxygenase (5-LOX) pathway is critical for pancreatic cancer cell growth and escape from apoptosis. Inhibition of 5-LOX blocks proliferation and induces apoptosis in human pancreatic cancer cells. However, the expression of 5-LOX and its downstream signaling pathway have not been investigated in human pancreatic adenocarcinoma. Reverse transcriptase-polymerase chain reaction revealed expression of 5-LOX mRNA in all pancreatic cancer cell lines tested including, PANC-1, AsPC-1, and MiaPaCa2 cells, but not in normal pancreatic ductal cells. The expression of 5-LOX protein in pancreatic cancer cell lines was demonstrated by Western blotting. Finally, 5-LOX up-regulation in human pancreatic cancer tissues was verified by intense positive staining in cancer cells by immunohistochemistry. Staining for the 5-LOX protein was particularly evident in the ductal components of the more differentiated tumors but not in ductal cells in normal pancreatic tissues from cadaver donors. Immunohistochemistry also revealed strong staining of cancer tissues with an antibody to the receptor of the downstream 5-LOX metabolite, leukotriene B(4). The current study demonstrated marked expression of 5-LOX and the leukotriene B(4) receptor in human pancreatic cancer tissues. These findings provide further evidence of up-regulation of this pathway in pancreatic cancer and that LOX inhibitors are likely to be valuable in the treatment of this dreadful disease.
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PMID:5-Lipoxygenase and leukotriene B(4) receptor are expressed in human pancreatic cancers but not in pancreatic ducts in normal tissue. 1216 67

The aims of this study were to determine the effects of (a) combining the epidermal growth factor receptor (EGFR) blocker (erlotinib) and the cyclooxygenase-2 inhibitor (celecoxib) on cell growth and apoptosis in human pancreatic cancer cell lines, (b) baseline EGFR expression on the potentiation of erlotinib-induced apoptosis by celecoxib, and (c) the effects of the combination on the expression of the COX-2, EGFR, HER-2/neu, and nuclear factor-kappaB (NF-kappaB). Baseline expression of EGFR was determined by Western blot analysis in five human pancreatic cancer cell lines. BxPC-3, PANC-1, and HPAC had high EGFR and MIAPaCa had low EGFR. Cells were grown in culture and treated with erlotinib (1 and 10 micromol/L), celecoxib (1 and 10 micromol/L), and the combination. Growth inhibition was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and apoptosis was assayed by ELISA. Reverse transcriptase-PCR was used to evaluate COX-2 and EGFR mRNA. EGFR, COX-2, and HER-2/neu expression was determined by Western immunoblotting. Electrophoretic mobility shift assay was used to evaluate NF-kappaB activation. Growth inhibition and apoptosis were significantly (P < 0.05) higher in BxPC-3, HPAC, and PANC-1 cells treated with celecoxib and erlotinib than cells treated with either celecoxib or erlotinib. However, no potentiation in growth inhibition or apoptosis was observed in the MIAPaCa cell line with low expression of the EGFR. Significant down-regulation of COX-2 and EGFR expression was observed in the BxPC-3 and HPAC cells treated with the combination of erlotinib (1 micromol/L) and celecoxib (10 micromol/L) compared with celecoxib- or erlotinib-treated cells. Celecoxib significantly down-regulated HER-2/neu expression in BxPC-3 and HPAC cell lines. Significant inhibition of NF-kappaB activation was observed in BxPC-3 and HPAC cell lines treated with erlotinib and celecoxib. (a) Celecoxib can potentiate erlotinib-induced growth inhibition and apoptosis in pancreatic cell lines, (b) high baseline EGFR expression is a predictor of this potentiation, and (c) the down-regulation of EGFR, COX-2, and HER-2/neu expression and NF-kappaB inactivation contributes to the potentiation of erlotinib by celecoxib.
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PMID:Simultaneous targeting of the epidermal growth factor receptor and cyclooxygenase-2 pathways for pancreatic cancer therapy. 1637 9

ONECUT1 (HNF-6) is the prototype of a new class of homeodomain transcription factors, that controls the development of pancreatic ducts during mouse development. In the present study, the role of ONECUT1 and its targeted genes TCF2, PKHD1 and CYS1 was analyzed in human pancreatic ductal adenocarcinoma (PDAC). mRNA levels of ONECUT1, TCF2, PKHD1 and CYS1 were measured in pancreatic tissues and pancreatic cancer cell lines by quantitative reverse-transcriptase polymerase chain reaction (QRT-PCR). Protein expression of ONECUT1 and TCF2 was assessed in pancreatic tissues by immunohistochemistry. ONECUT1 was transfected into Panc-1 and T3M4 pancreatic cancer cells and its effects on anchorage-dependent and -independent growth as well as invasion and adhesion were analyzed. Median mRNA levels of ONECUT1, TCF2, PKHD1 and CYS1 were 7.7-, 2.0-, 5.7- and 3.8-fold higher in normal tissues than in PDAC tissues. ONECUT1 protein was expressed in normal acinar and ductal cells, but neither in the cancer cells of PDAC tissues nor in 7 of 8 cultured pancreatic cancer cell lines. There was a significant positive correlation between ONECUT1 and TCF2, CYS1, and PKHD1 mRNA levels in PDAC tissues. Transfection of ONECUT1 into pancreatic cancer cells resulted in up-regulation of the target gene TCF2, a reduction in invasiveness, but no change in adhesion or growth. In conclusion, ONECUT1 expression is lost in pancreatic cancer cells, suggesting a tumor suppressor function in this malignancy.
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PMID:Loss of ONECUT1 expression in human pancreatic cancer cells. 1809 90

Pancreatic ductal adenocarcinoma (PDAC) shows the worst mortality among the common malignancies and development of novel therapies for PDAC through identification of good molecular targets is an urgent issue. Among dozens of over-expressing genes identified through our gene-expression profile analysis of PDAC cells, we here report CST6 (Cystatin 6 or E/M) as a candidate of molecular targets for PDAC treatment. Reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemical analysis confirmed over-expression of CST6 in PDAC cells, but no or limited expression of CST6 was observed in normal pancreas and other vital organs. Knock-down of endogenous CST6 expression by small interfering RNA attenuated PDAC cell growth, suggesting its essential role in maintaining viability of PDAC cells. Concordantly, constitutive expression of CST6 in CST6-null cells promoted their growth in vitro and in vivo. Furthermore, the addition of mature recombinant CST6 in culture medium also promoted cell proliferation in a dose-dependent manner, whereas recombinant CST6 lacking its proteinase-inhibitor domain and its non-glycosylated form did not. Over-expression of CST6 inhibited the intracellular activity of cathepsin B, which is one of the putative substrates of CST6 proteinase inhibitor and can intracellularly function as a pro-apoptotic factor. These findings imply that CST6 is likely to involve in the proliferation and survival of pancreatic cancer probably through its proteinase inhibitory activity, and it is a promising molecular target for development of new therapeutic strategies for PDAC.
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PMID:Over-expression of cysteine proteinase inhibitor cystatin 6 promotes pancreatic cancer growth. 1875 76

Despite the recent introduction of the new anticancer agents gemcitabine (GEM) and TS-1, as well as combination regimens such as GEM plus cisplatin (CDDP), pancreatic cancer treatment remains relatively ineffective. Both intrinsic and acquired resistance to chemotherapy are major roadblocks to the successful treatment of pancreatic cancer patients. The aims of this study were to examine the expression of multidrug resistance-associated proteins (MRPs) MRP1, MRP2 and MRP3 and to evaluate the correlation between MRP2 expression and CDDP resistance in human pancreatic cancer. Five human pancreatic cancer cell lines and several surgically resected pancreatic cancer tissues were subjected to reverse-transcriptase (RT)-PCR, real-time PCR and immunohistochemical analysis. While MRP1 and MRP2 mRNA was expressed in all cell lines, MRP3 mRNA was only detected in two cell lines. In resected pancreatic cancer tissues, only MRP2 mRNA was expressed and it was overexpressed compared with normal pancreatic tissues. MRP2 protein expression was observed in 77.5% (31/40) of cancer tissues, primarily in the cytoplasm of cancer cells, but was not observed in normal pancreatic tissue. Two CDDP-resistant pancreatic cancer cell line SUIT-2 variants, SUIT-2-CD3 and SUIT-2-CD4, were established by continuously administering 10 nM CDDP to SUIT-2 cell lines for 3 and 4 months, respectively. Incubation of these cells with CDDP in the presence of anti-MRP2 antibody or the MRP2 inhibitor MK-571 in a growth inhibition assay demonstrated that the CDDP-resistant variants were more resistant to CDDP than the parent cell line and this resistance was diminished by either anti-MRP2 antibody or MK-571. Moreover, RT-PCR and real-time PCR revealed that while induction of MRP2 mRNA expression was increased in CDDP-resistant compared with parent cells, MRP1 and MRP3 expression remained unchanged. These observations suggest that MRP2 may correlate to intrinsic and acquired resistance for CDDP in human pancreatic cancer.
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PMID:Expression of multidrug resistance-associated protein 2 is involved in chemotherapy resistance in human pancreatic cancer. 1902 Jul 51


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