Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Circulating cancer cells in the blood play a central role in the metastatic process. Their number can be very small and techniques for their detection need to be both sensitive and specific. Polymerase chain reaction (PCR) has been successfully used to detect small numbers of tumour cells in haematological cancer in which abnormalities in DNA are sufficiently consistent to make this possible. For most solid tumours this not yet feasible. However, we have found that reverse transcriptase (RT)-PRC for tissue-specific gene expression is a useful technique for identifying small numbers of circulating cells in melanoma and neuroblastoma patients. In this report we describe detection of colon carcinoma cells by RT-PCR using CK 20 mRNA as a marker. Unlike other cytokeratin genes examined (CK 8 and CK 19), CK 20 was not transcribed in normal haematopoietic cells. This suggests a role for RT-PCR in the detection of colon carcinoma metastasis in blood and bone marrow, using CK 20 as the target gene. Future analysis of clinical material will determine the clinical significance of this technique.
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PMID:Detection of epithelial cancer cells in peripheral blood by reverse transcriptase-polymerase chain reaction. 753 Sep 83

Keratin filament are characteristically present in epithelial cells and tumors, but have also been detected in many normal and neoplastic non-epithelial cell types using immunohistochemical techniques. To investigate the validity of this seemingly aberrant protein expression, we applied the highly sensitive polymerase chain reaction (PCR) technique to study keratin gene expression in a variety of non-epithelial tissues. Total RNA was extracted from nine samples of leiomyosarcoma, four non-Hodgkin's lymphoma, seven normal bone marrows, normal lymph node, normal peripheral blood cells, freshly isolated and cultured endothelial cells, cultured skin fibroblasts, and the myeloid leukemia cell line HL-60. Amplification primers and probes for the three most primitive keratin types (8, 18, and 19) were synthesized using published gene sequences. RNA from the breast carcinoma cell line MCF-7, known to be rich in all three keratins, was used as positive control. Concurrently run actin primers were used to confirm RNA integrity. After an initial cycle with reverse transcriptase, PCR amplification was performed for 30 cycles. Southern blots of the PCR products showed variably intense bands corresponding to keratin 8 and 18 gene products in all samples, offering conclusive evidence of keratin gene expression in cells of both stromal and hematopoietic derivation. However, keratin 19 gene transcription was not nearly so ubiquitous, being detected in normal fibroblasts and endothelial cells, two of four non-Hodgkin's lymphoma and four of nine leiomyosarcoma, but not in normal lymph node, peripheral blood cells, HL-60 cells, or any of the seven normal bone marrows examined. Dilutional experiments showed PCR to be highly sensitive in the detection of keratin 19 gene expression, capable of registering one MCF-7 cell in 10(6) HL-60 cells. These studies show that variable levels of keratin 8 and 18 gene expression may be detected by PCR in a wide variety of non-epithelial tissues, supporting previous immunohistochemical and phylogenetic studies. However, keratin 19 gene expression appears to be more restricted and was not evident in any hematopoietic cells devoid of contaminating stromal elements. These findings suggest a role for PCR in the detection of epithelial micrometastasis in certain sites, particularly bone marrow.
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PMID:Keratin gene expression in non-epithelial tissues. Detection with polymerase chain reaction. 768 61

To investigate whether ESE-1 gene abnormalities are involved in alterations of epithelial cell differentiation in squamous anal cancer ESE-1 expression and structure were screened in six patients by reverse transcriptase-polymerase chain reaction (RT-PCR) and automated sequence analysis. The complete cDNA of isoform ESE-1b was always expressed and correctly spliced, with single nucleotide polymorphism being observed in two cases. Presence of ESE-1b point mutations was excluded. Expression of SPRR2A and ENDOA/CK8, two epithelium-specific ESE-1 target genes, were revealed by RT-PCR in all cases. This first report of expression of ESE-1, and of SPRR2A and ENDOA/CK8 (both related to terminal differentiation in different types of epithelia lining) in anal cancer excludes the hypothesis that these genes influenced carcinogenesis in our patients. Despite selecting of patients without clinical evidence of HPV infection, PCR consistently revealed HPV-16 DNA, highlighting the importance of HPV infection in anal cancer.
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PMID:Expression analysis and mutational screening of the epithelium-specific ets gene-1 (ESE-1) in patients with squamous anal cancer. 1089 34

The suitability of "real-time" quantitative reverse transcriptase polymerase chain reaction (RT-PCR) for the detection of isolated carcinoma cells in bone marrow was investigated by evaluating the expression of cytokeratin (CK)7, CK8, CK18, CK19, and CK20 in 17 gastrointestinal cancer cell lines, 64 control bone marrow specimens from noncancer patients, and 30 bone marrow specimens from patients with gastric or colorectal cancer. RT-PCR products for CK8 and CK18 were detected in all cancer cell lines, but only 16, 5, and 11 cell lines provided evidence for CK19, CK7, and CK20 transcription. Variable numbers of bone marrow specimens from noncancer patients demonstrated background transcription of CK8 (78.1%), CK18 (95.3%), CK19 (35.9%), CK20 (29.6%), and CK7 (16.7%). Maximal background transcription for CK8, CK18, and CK19 ranged from 52.2 to 56.1 copies/10(3) copies glyceraldehyde-3-phosphate dehydrogenase (GAPDH), the corresponding values of 0.06 and 0.76 copies for CK7 and CK20 being distinctly lower. When maximal background values were used as a threshold value to define positivity in tumor cell dilution experiments, sensitivity levels of one tumor cell in 10(4) bone marrow cells were determined for CK7 and CK20 RT-PCR assays. Maximal background expression values of the different CKs as obtained in the control series were exceeded once (CK20), twice (CK18 and CK19), and 18 times (CK7) in bone marrow specimens from cancer patients, with none of these specimens exceeding the maximal background expression value of CK8. We conclude that RT-PCR for CK8, CK18, and CK19 cannot be recommended for the detection of isolated tumor cells in bone marrow of cancer patients. On the other side, the limited number of gastric and colorectal cancer cell lines expressing CK7 and CK20 indicates that assay sensitivity for these CKs might be limited because of their selective expression by carcinoma cells.
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PMID:Transcription of cytokeratins 8, 18, and 19 in bone marrow and limited expression of cytokeratins 7 and 20 by carcinoma cells: inherent limitations for RT-PCR in the detection of isolated tumor cells. 1159 48

Cholestasis is associated with retention of potentially toxic bile acids and profound cytoskeletal alterations of hepatocytes. Given the well-established cytoprotective role of hepatocyte keratins this study aimed to determine the effects of cholestasis on the cytokeratin (CK) intermediate filament network in mouse liver. Mice were subjected to common bile duct ligation or sham operation. Mice were also fed a cholic acid or ursodeoxycholic acid (UDCA)-supplemented diet (0.1%, 0.5%, and 1%) or control diet for 7 days. CK 8 and CK 18 expression was studied by competitive reverse transcriptase-polymerase chain reaction, in situ hybridization, Western blot analysis, and immunofluorescence microscopy. Common bile duct ligation and cholic acid feeding significantly stimulated CK 8 and CK 18 mRNA and protein levels compared to controls, whereas UDCA had no effect. CK overexpression was accompanied by pronounced phosphorylation. Our results show that potentially toxic bile acids induce hepatocytic CK 8 and CK 18 expression and phosphorylation whereas nontoxic UDCA has no effect on CKs. Thus, increased hepatocellular CK expression and phosphorylation in cholestasis may be caused by retention of toxic bile acids and reflect a hepatocellular stress response with potential beneficial effects.
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PMID:Cytokeratins as targets for bile acid-induced toxicity. 1183 69

Cytokeratins (CKs) are a subgroup of intermediate filament proteins that take part in forming the cytoskeleton. The epithelial cells in different organs express distinct CKs, and this expression may be modified during malignant transformation. Here we describe the use of reverse transcriptase-polymerase chain reaction followed by Southern blotting to determine the profile of expression of CKs in both normal and malignant laryngeal samples. Thirty-six samples were subjected to histologic examination and classified as 17 squamous cell carcinomas, 3 dysplastic lesions, and 16 normal samples. CK8 and CK19 were expressed in almost all samples, both cancerous and normal, and were therefore used to verify the integrity of RNA. Expression of CK2, CK9, and CK20 was not detected in any of the samples, normal or cancerous. CK15 and CK18 showed low sensitivity for detection of cancer (36.4% and 45.5%, respectively). CK10 showed relatively high sensitivity (91%), but only moderate specificity (69.2%). Only CK17 showed both high sensitivity and specificity (91% and 92.3%, respectively; positive predictive value, 91%). We propose that CK17 may be considered a promising candidate to use as a molecular marker for malignant transformation in laryngeal squamous cell carcinoma.
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PMID:Detection of cytokeratins in normal and malignant laryngeal epithelia by means of reverse transcriptase-polymerase chain reaction. 1186 67

Chronic cholestasis is associated with retention of bile acids and profound cytoskeletal alterations in hepatocytes including Mallory body (MB) formation. The mechanisms responsible for MB formation in cholestatic liver diseases are unclear. The aim of our study was to determine the relevance of cholestasis and bile acids for MB formation. For this purpose mice received a 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-supplemented diet for 2.5 months to induce MB formation. After recovery from DDC intoxication for 4 weeks followed by disappearance of MBs, these drug-primed mice were subjected to DDC refeeding, common bile duct ligation (CBDL), and feeding of a cholic acid (CA)-supplemented diet for 7 days, respectively. Cytokeratin (CK) 8 and CK 18 expression was studied by competitive reverse transcriptase-polymerase chain reaction and Western blot analysis. Cytoskeletal alterations of hepatocytes and MB formation were monitored by immunofluorescence microscopy and immunohistochemistry using CK-, ubiquitin-, and MB-specific antibodies. Like DDC refeeding, both CBDL and CA feeding of drug-primed mice significantly increased CK 8 and CK 18 mRNA and protein levels (with excess of CK 8) and resulted in ubiquitination and abnormal phosphorylation of CKs. Furthermore, CBDL and CA feeding resulted in rapid neoformation of MBs in drug-primed mice. It is concluded that MB formation in cholestatic liver diseases may be triggered by the action of potentially toxic bile acids.
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PMID:Bile acid-induced Mallory body formation in drug-primed mouse liver. 1246 18

To date, the hepatic differentiation of embryonic stem (ES) cells into biliary epithelial (BE) cells has only been identified in hepatocytes. In this study, an attempt was made to induce the differentiation of ES cells to BE cells. In order to induce hepatic, and then BE cell differentiation, growth factors such as TGF, FGF, HGF and EGF were added to the culture medium supplied to embryonic bodies (EBs) that were derived from ES cells. The marker genes and corresponding proteins of hepatocytes and BE cells such as AFP, ALB, CK8, CK18, CK7, CK19 and GGT, etc. were detected by reverse transcriptase-polymerase chain reaction (RT-PCR), immunocytochemistry (ICC) and enzymatic histochemistry. Lastly, the ratio of BE-like cells to all EBs cells was analyzed and determined by flow cytometry (FCM). Hepatocyte and BE cell marker genes and proteins were found to be expressed in the cytoplasm of differentiated cells. On day 10 of differentiation, many round structures appeared in the EBs culture system and the marker proteins of BE cells were found to be expressed in these structures. The BE cell differentiation ratio continually increased from its initial value of 1.7% on day 13 to 7.4% on day 21. ES cells were found to be able to differentiate into BE cells when cultured using medium with appropriate cell growth factors. These BE cells may be a novel source of differentiated cell types for liver engineering.
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PMID:Hepatic differentiation of mouse ES cells into BE cells in vitro. 1660 Jun 44

Adenocarcinoma of the prostate comprises 95% of all prostate cancer. Commercially available primary cultures of "normal" prostate epithelial cells, PrECs, have been used as a convenient model to investigate neoplastic transformation. Here PrECs were characterized for the expression of lineage- and developmental-specific markers cytokeratin (CK) 8 and 18, p63, chromogranin A, TMEPAI, S100P, NKX 3.1, ANKH, and FN 1 as well as androgen receptor and prostate-specific antigen by Western blot and Northern blot analyses, immunohistochemistry, reverse transcriptase-polymerase chain reaction (RT-PCR), and quantitative real-time PCR. Immunohistochemical staining detected PrECs positive in varying degrees for p63, CK 8, and CK 18, with only the rare cell being positive for chromogranin A. The PrECs also tested positive for p63 protein by Western blot analysis. RT-PCR with PrEC cDNA showed products for FN 1 and S100P but not for ANKH and androgen receptor or prostate-specific antigen. This profile of markers in PrEC cells is consistent with that expected for pubertal prostate epithelial cells.
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PMID:Molecular analysis and characterization of PrEC, commercially available prostate epithelial cells. 1661 9

The MHB-2 cell line, established from a mouse hepatoblastoma (HB), was subjected to the reverse transcriptase-polymerase chain reaction (RT-PCR) for evaluation of gene expression related to cell differentiation. RNAs for c-kit, CD34, thy-1, albumin, cytokeratin (CK) 8, 18 and 19 could be detected, but expression of alpha-fetoprotein, glucose-6-phosphatase, tyrosine aminotransferase and CK7 was not observed. MHB-2 cells were positive for CK8/18 but negative for c-kit, CD34, thy-1 and albumin on protein level. Immunohistochemical staining of the HB in vivo revealed diffusely expressed c-kit. Thy-1-positive HB cells were sparsely observed, but the tumor was negative for CD34 and rarely positive for CK8/18. By in situ hybridization, the HB was positive for CK18 but negative for CK19. Slight expression of albumin, but the lack of immature hepatocytic marker suggested some heterogeneous hepatocyte or an undifferentiated cell from other origin. Furthermore, positive expression of CK19 as well as CK8 and CK18 in culture strongly suggested the differentiation into a biliary lineage or the bidirectional state. In conclusion, the present study indicated the mouse HB to have de-differentiated, bipotent, or biliary-like cell characteristics, and considering the histological difference between HB and biliary tumors, it suggests the mouse HB cells are closely like some sort of hepatic undifferentiated cells.
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PMID:Evaluation of gene expression related to hepatic cell maturation and differentiation in a chemically induced mouse hepatoblastoma cell line. 1763 80


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