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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A simple method for the detection and localization of mRNA in single frozen breast biopsy tissue sections is described. Several extraction procedures were compared. Resuspending sections, which could be left at 0 or -70 degrees C for up to 20 min in H2O containing RNAse inhibitor, optimally released RNA with minimal DNA contamination. Reverse transcription followed by polymerase chain reaction amplification using specific primers yielded products visible by ethidium bromide staining (abundant sequences) or after Southern blotting (low copy message). We found that it was possible, by microdissection, to separate stromal and tumor cells and demonstrated differential expression of several genes in the two populations. With 40 cycles of amplification, dissected stromal and tumor tissue both yielded products encoding glyceraldehyde 3'-phosphate dehydrogenase but only the tumor cells gave products with primers specific for either keratin 19, heat shock protein 89 alpha or the fig oncogene, which encodes one of the fibroblast growth factor receptors that we have recently found to be expressed in breast cancers. With refinement of the dissection technique this offers a very sensitive analytical tool for measuring and defining the cellular sites of synthesis of low-abundance message, requiring only single histological sections.
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PMID:Polymerase chain reaction-aided analysis of gene expression in frozen tissue sections. 137 4

Deletion of the short arm of chromosome 1 is among the most recurrent cytogenetic alterations found in neuroblastoma and has been associated with short survival. However, this prognostic information, which relies on time-consuming techniques, is not yet routinely exploited. In order to set up a reliable and simple routine test to determine 1p deletion in neuroblastoma, we have used the polymerase chain reaction to genotype neuroblastoma DNA at 2 loci containing a variable number of tandem repeats and located on the distal part of the short arm of chromosome 1. Agarose gel electrophoresis and ethidium bromide staining of the amplification products enable a simple determination of constitutional and tumor genotypes at these loci to be made. A total of 37 samples from 29 patients were studied with this technique. Loss of heterozygosity (LOH) could be identified in 8 cases. In each case the results obtained were in agreement with those achieved by the Southern procedure. This technique will be of particular interest in the pretherapeutic analysis of 1p deletions in small tumor samples obtained by fine-needle aspirates of the primary tumor. It should also enable retrospective studies from paraffin-embedded tumor fragments to be made and provide information for the analysis of tumor heterogeneity in neuroblastoma and in other tumors with 1p deletions.
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PMID:PCR assay for chromosome 1p deletion in small neuroblastoma samples. 139 34

The success of a predictive assay for radiotherapy relies on the use of one or more tumor cell traits that equate with tumor radioresistance or radiosensitivity. These traits can be divided into intrinsic (genetic) and extrinsic (epi-genetic) factors. Most probably, a tumor's response to radiotherapy will be influenced by both of these sets of traits. Radiobiological analysis of cultured cells derived from explanted tumors of head and neck patients has shown that in vitro survival of tumor cells is not the only factor affecting tumor radiocurability. Two possible reasons are the high degree of selection involved in growing the cells in vitro and the inability to assess the contribution of the cell-cell contact effect with cultured cells. A possible means of overcoming both of these problems would be an assessment of the radiosensitivity of the cell population immediately after removal from the tumor. Since a good correlation exists between intrinsic cellular radioresistance and DNA double-strand break repair (DSBR) as assayed by the Neutral Elution technique [21], we have investigated the feasibility of using asymmetric field inversion gel electrophoresis (AFIGE) in identifying resistant tumor cells in vitro. AFIGE has several advantages over neutral elution in that it is faster (approximately 60-80 samples can be run on the same agarose gel) and, most importantly, one can visualize DNA damage and repair by staining the DNA with ethidium bromide.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The use of asymmetric-field inversion gel electrophoresis to predict tumor cell radiosensitivity. 141 May 78

The feasibility of diagnosing the malignancy and viability of intraparenchymal brain tumours using Gd-DTPA, enhanced and unenhanced T1-weighted MRIs was investigated. The relationship between the Gd-DTPA enhancement pattern, the growth fraction (GF) determined by using the anti-bromide-oxyuridine (BrdU) monoclonal antibody, the clinical condition, the proliferative potential and the change of Gd-DTPA enhancement over time was studied. Forty-five patients with intracranial tumours were studied with the static method of Gd-DTPA MRI. The enhanced effect in Gd-DTPA MRIs was dependent on tumour-cell density, vascularization, necrosis, and dilatation of vascular lumen. Tumour-cells were observed in eighty-seven of eighty-nine specimens taken from areas with Gd-DTPA enhanced MRIs. Seventy-four percent of these specimens (64 of 87) showed a malignancy of more than 5% growth fraction. On the other hand, tumour cells were observed in twenty-seven of fifty-six specimens taken from areas with Gd-DTPA unenhanced MRIs. Eighty-five percent of these specimens (23 of 27) showed a malignancy value of less than 5% GF. However, fifteen percent of these specimen showed values between 5 and 15% GF. In the kinetic study of Gd-MRIs five patients who were in a clinically stable condition and one patient who had radionecrosis showed a constant pattern of enhancement or slightly increased enhancement 30 min after injection compared to 4 min after injection. Therefore, GD-DTPA MRI can be used effectively in the diagnosis of tumour viability and malignancy after treatment.
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PMID:Malignancy and viability of intraparenchymal brain tumours: correlation between Gd-DTPA contrast MR images and proliferative potentials. 141 20

We describe a novel system for measuring the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction in three-dimensional histoculture which is no longer dependent on colorimetric determination of extracted formazan, but rather is based on a pixel image analysis of formazan crystals, and which allows intratumor heterogeneity to be taken into account. The MTT test is based on the enzymatic reduction of the tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-dipheniltetrazolium bromide to formazan crystals by living, metabolically active cells, but not in dead cells. The reaction was carried out in situ in six-well plates on gel-supported histocultured human tumors. After a 24-h incubation with different drugs the tumors were incubated with a solution of MTT. Frozen sections of the tumor pieces were made and the slides were then stained with a propidium iodide solution, whose fluorescence is proportional to the number of cells present. We demonstrate here that the formazan crystals, formed by MTT reduction, reflect polarized light and that this can be quantified by using an image analysis system based on bright-pixel quantitation directly on a frozen section of the original tissue. Combined with the use of the fluorescent dye propidium iodide, also measured by pixel analysis, we can express a ratio between the total amount of MTT reduction and the total number of cells present in the specimen that expresses the effect of drugs on the histocultured tumors. Since histology is well maintained in histoculture it is possible to take into account the heterogeneity present in the tumor with regard to drug response.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Noncolorimetric measurement of cell activity in three-dimensional histoculture using the tetrazolium dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide: the pixel image analysis of formazan crystals. 144 62

After activation by interferon-gamma (INF-gamma) and lipopolysaccharide(LPS), mouse peritoneal macrophages were cocultured with P388 parental cell line (P388/PRT) and its adriamycin (ADM)-, cisplatin(CDDP)-, cyclophosphamide(CPM)-, and mitomycin-C(MMC)-resistant cell lines for one day at effector:target ratios (E:T) of 10:1, 5:1, and 2:1. The direct 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide (MTT) cleavage assay and a new indirect MTT assay as well as clonogenic assay were used to quantitate activated macrophage-mediated cytotoxicity to these non-adherent leukemia targets. The results revealed that all the P388 cell lines can be suppressed efficiently by activated macrophages, but P388 CPM- and MMC-resistant cell lines (P388/CPM, P388/MMC) were more susceptible than P388/PRT while P388 ADM- and CDDP-resistant cell lines (P388/ADM, P388/CDDP) shared equal level of survival rates with P388/PRT. This study also showed that both non-activated and activated macrophages can produce formazan in a high level, which can interfere with the final results of direct MTT assay. The new indirect MTT assay can avoid such interference by separating the effectors from the targets before performing the MTT assay and reflects the real viability of the targets so the indirect MTT assay developed in this study could be a better way to examine cytostatic and cytotoxic effect of activated macrophages on non-adherent tumor cells in vitro.
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PMID:Differential macrophage-mediated cytotoxicity to P388 leukemia cells and its drug-resistant cells examined by a new MTT assay. 146 25

Promotion of 'initiated' JB6 epidermal cells to the tumor phenotype can be effected by 12-O-tetradecanoylphorbol-13-acetate treatment, by stimulation of epidermal growth factor (EGF) receptor activity with EGF or transforming growth factor alpha and by exposure to the isoquinoline derivative H7. When these cells were incubated with pertussis toxin (PTX), induction of anchorage-independent growth by all four promoting substances was suppressed. The inhibition is specific since cell proliferation is not affected, suggesting that activation of a Gi protein is essential for promotion of the epidermal cells. This interpretation is strongly supported by the observation that the wasp poison mastoparan, which is known to mimic receptor-mediated activation of certain Gi proteins, also promoted anchorage independence. Immunological data and partial amino acid sequence analysis of ADP-ribosyl alpha i isolated from PTX-treated JB6 cells indicate that a Gi-2 protein is a mediator to tumor promotion in this system. The inhibitory action of 4-bromophenacyl bromide may point to a coupling of the Gi protein to phospholipase A2. From our data we infer that promoters induce the tumor phenotype in 'initiated' JB6 epidermal cells by activating epigenetically the same Gi protein that in a number of adrenal and ovarian tumors appears to be persistently activated by mutational events.
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PMID:Epigenetic activation of Gi-2 protein, the product of a putative protooncogene, mediates tumor promotion in vitro. 147 50

Clinical and experimental observations suggest that tumor-induced endothelial cell injury may be one of several initial events in the establishment of tumor metastases. To test this hypothesis, the authors have analyzed the interaction of malignant melanoma (ST-ML-12) multicenter tumor spheroids with endothelial cell monolayers in a three-dimensional coculture system. After 1.5 hours of interaction, the authors observed a toxic effect on endothelial cells in the perispheroid region. The latter was demonstrated by testing membrane integrity with the fluorescent probes acridine orange/ethidium bromide and resulted in sensitivity to shear stress of the damaged cells. The endothelium then underwent a regenerative cycle to replace the denuded halo. Addition of the oxygen radical-scavenging enzyme superoxide dismutase to the culture medium prevented this endothelial cell damage in a dose-dependent manner for up to 12 hours. By contrast, catalase, deferoxamine mesylate, allopurinol, and the proteinase inhibitors soybean trypsin inhibitor and aprotinin were not protective under the same conditions. The endothelial damage was dependent on the attachment of the spheroids. Medium conditioned by ST-ML-12-spheroids proved to be ineffective. A similar, but less prominent, deleterious effect was seen when human peritoneal mesothelial cells were used in place of the human umbilical vein endothelial cells. Spheroids of the uroepithelial cell line HU-609 were used as control. No toxicity was observed in these cocultures. Melanin biosynthesis is associated with the production of oxygen-derived free radicals. The results suggest a possible implication of these free radicals in metastasis formation of malignant melanoma.
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PMID:Interaction of human malignant melanoma (ST-ML-12) tumor spheroids with endothelial cell monolayers. Damage to endothelium by oxygen-derived free radicals. 151 67

The antitumor effects of mitoxantrone (MITO) and the various mechanisms involved therein were investigated in the adriamycin sensitive (P388/S) and resistant (P388/ADR) P388 leukemia cells. Utilizing the MTT (3-[4,5/dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay, MITO concentration less than 100 ng elicited 50% inhibition of P388/S tumor cell survival, while a 10 times greater dose of MITO was required to inhibit the P388/ADR cell survival by 50%. A MITO dose dependent inhibition of DNA, RNA and protein biosynthesis was observed in the sensitive cells, while MITO elucidated a negligible effect on the macromolecular biosynthesis in the resistant tumor cells. Induction of DNA strand scission was observed in P388/S cells exposed to 0.1 and 1 microgram/ml MITO, while a minimal formation of DNA lesions was evident in the P388/ADR cells treated with 5 micrograms/ml MITO. These strand breaks were found to be not associated with proteins in either P388/S or P388/ADR cells. Generation of free radicals due to MITO and formation of alkylating metabolites of MITO were found to be not involved in the cytotoxic response of MITO against P388/S and P388/ADR cells. MITO did not affect the glutathione based detoxification mechanism of the sensitive and resistant tumor cells. Results indicate that in spite of reduced intracellular drug retention and induction of DNA strand breaks in P388/ADR cells other hitherto unknown mechanisms besides DNA binding might be involved in the antitumorigenic potential of MITO.
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PMID:Antineoplastic activity of mitoxantrone and its biological interactions in parental and multidrug resistant subline of P388 murine leukemia cells. 152 4

The chemosensitivities of squamous cell carcinoma (SCC) tissues from the head and neck area were compared to findings of adenocarcinoma, mainly from digestive organs. The sensitivity of each tissue was determined using the in vitro succinate dehydrogenase (SD) inhibition test, which shares a common principle with the 3-(4,5-dimethyl-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Tumor tissues were obtained at surgery or biopsy. Anticancer drugs tested were carboquone, Adriamycin, mitomycin C, cisplatin (CDDP), aclacinomycin A, 5-fluorouracil and 1-hexylcarbamoyl-5-fluorouracil with 10 times the peak plasma concentration, respectively. The means +/- standard deviations of SD activities in SCC tissues were significantly lower than those in adenocarcinoma tissues (p less than 0.001), and the sensitivity rates of SD activity in SCC tissues had a higher value than those in adenocarcinoma tissues (p less than 0.05), against each drug. Our study showed that CDDP-based combination regimens might be effective for SCC tissues. The chemosensitivity of each excised tissue should be tested, in order to prescribe sensitive, effective drugs for each patient.
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PMID:Comparison of in vitro anticancer chemosensitivity between human squamous cell carcinoma and adenocarcinoma. 152 69


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