Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

EMT-6 murine mammary tumors were made resistant to cis-diamminedichloroplatinum (II) (CDDP), carboplatin, cyclophosphamide (CTX), or thiotepa in vivo by treatment of tumor-bearing animals with the drug during a 6-month period. In spite of high levels of in vivo resistance, no significant resistance was observed when the cells from these tumors were exposed to the drugs in vitro. The pharmacokinetics of CDDP and CTX were altered in animals bearing the respective resistant tumors. The resistance of all tumor lines except for the EMT-6/thiotepa decreased during 3 to 6 months in vivo passage in the absence of drugs. These results indicate that very high levels of resistance to anticancer drugs can develop through mechanisms that are expressed only in vivo.
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PMID:Tumor resistance to alkylating agents conferred by mechanisms operative only in vivo. 210 97

Several studies have examined the synergism of hyperthermia or chemotherapy agents in combination with photodynamic therapy (PDT) to enhance tumor eradication. In our unique approach to treatment, multiple photosensitizers and wavelengths were used: two photosensitizers, Photofrin II and meso-tetra-(4-sulfonatophenyl)-porphine (TPPS4), irradiated at the appropriate therapeutic wavelength for each photosensitizer. EMT-6 mammary tumors were induced in the flanks of BALB/c mice. The mice were assigned to a control group (50 mice) or treatment group (150 mice). All treatment animals and some control animals received photosensitizing drug (5 mg/kg of TPPS4, 5 mg/kg of Photofrin II, or 2.5 mg/kg of both TPPS4 and Photofrin II). All treatment animals and some control animals also received light treatment (630 nm for TPPS4 and/or 658 nm for Photofrin II). The results show that the approach using both drugs and the corresponding therapeutic wavelengths enhanced the effectiveness of PDT. This approach achieved a cure rate of up to 100%, which was, depending on the light intensity used, as much as 40% greater than the rate achieved by the approach using one drug and one wavelength. The results also show that lesser amounts of drug and/or light may be required if both drugs and wavelengths are used, thus lowering the chances of side effects common to PDT. Furthermore, the results indicate that the increased tumor kill is due to a synergistic effect of the two photosensitizers that was tested on the tumor microvasculature in the first few hours after PDT.
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PMID:Use of multiple photosensitizers and wavelengths during photodynamic therapy: a new approach to enhance tumor eradication. 213 4

Cytogenetic studies on fresh human breast cancers revealed that homogeneously staining regions (HSRs), which are assumed to represent DNA amplification, are observed in almost half of the cases. To search for a possible relationship between HSRs and proto-oncogene amplification, 16 proto-oncogenes, including ERBB2, were studied by Southern blot analysis in four tumors with two or three HSRs, and in three tumors without HSRs. Only four proto-oncogenes were found to be amplified in at least one tumor each: HST and INT2 (x3), MYC (x2-3), and FES (x greater than 10). The large sizes of the HSRs, which each corresponded to several percent of the haploid genome, were hardly compatible with the low rate of amplification, except for FES and then only if a large adjacent segment was co-amplified. This incomplete correlation was demonstrated by in situ hybridization, using biotinylated probes, which showed fluorescent spots on only one HSR for FES in one tumor and for INT2 in another one. Our results indicate that most of the large amplifications corresponding to HSRs do not involve the proto-oncogenes usually studied in breast cancer. The large amplification of FES, detected in one tumor, may be coincidental.
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PMID:Proto-oncogene amplification and homogeneously staining regions in human breast carcinomas. 217 39

Tumor necrosis factor (TNF-alpha) is a cytokine produced by macrophages and monocytes, and has been shown to have cytolytic, cytostatic or growth-stimulatory activity on transformed cells. However, the mechanism of these growth modulating activities of TNF-alpha is unknown. By studying the response of different oncogene-transformed NIH3T3 cells to TNF-alpha, we showed that the oncogene v-abl confers resistance to the cytostatic and cytolytic activities on TNF-alpha compared to the parental NIH3T3 cells. Most interestingly, v-abl expression also resulted in a growth-enhancing response to TNF-alpha at up to the highest dose of 6,400 units/ml. These altered properties were not due to the transformation event itself, since EJ-ras oncogene transformed NIH3T3 cells were more susceptible to TNF-alpha than the parental cells. Moreover, EMT-6, a mouse adenocarcinoma cell line, which responded similarly to NIH3T3 cells, did not show growth-enhancement at high TNF-alpha dosages. Though resistant to the direct cytotoxic activity of TNF-alpha, the v-abl transformed cell line was effectively killed by macrophages, as were the other cell lines. This suggests tumor cell killing by macrophages must involve mechanisms in addition to the secretion of TNF-alpha.
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PMID:V-abl confers resistance and growth advantage to TNF-alpha in NIH3T3 cells. 218 46

The protein kinase C (PKC) inhibitor staurosporine was found to dramatically alter the actin microfilament cytoskeleton of a variety of cultured cells, including PTK2 epithelial cells, Swiss 3T3 fibroblasts, and human foreskin fibroblasts. For example, PTK2 cells exposed to 20 nM staurosporine exhibited a progressive thinning and loss of cytoplasmic actin microfilament bundles over a 60-min period. During this time microtubule and intermediate filament systems remained intact (as shown by immunofluorescence and at higher resolution by photoelectron microscopy), and the cells remained spread even though microfilament bundles were absent. Higher doses of staurosporine or longer exposure times at lower doses resulted in morphological alterations, but even severely arborized cells recovered normal morphology and actin patterns after a wash and an incubation for several hours in fresh medium. The actin filament disruption induced by staurosporine was distinguishable from the actin reorganization induced by exposure to the tumor promoter (and activator of PKC) phorbol myristate acetate (PMA). Swiss 3T3 cells made deficient in PKC by prolonged exposure to PMA (PKC down-regulation) exhibited actin alterations in response to staurosporine which were comparable to those in cells which had not been exposed to the phorbol ester. In a parallel control experiment, the actin cytoskeleton of PKC-deficient 3T3 cells was unaffected in response to PMA, consistent with down-regulation of this kinase. While the exact mechanism of staurosporine-induced actin reorganization remains to be determined, the observed effects of staurosporine on PKC-deficient cells make a role for PKC unlikely. These results indicate the need for care when staurosporine is employed as an inhibitor of protein kinase C in studies involving intact cells.
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PMID:Staurosporine induces dissolution of microfilament bundles by a protein kinase C-independent pathway. 218 42

Polymerase chain reaction (PCR) is a novel tool for the in vitro amplification of DNA segments up to several kb. Repeated cycles of DNA synthesis by heat-stable Taq DNA polymerase enables to obtain more than 10(5) copies of the target sequence. Recently its enormous attitude of amplification has been applied for the detection of tumor-specific gene alterations. Examples include the detection of point mutation of RAS oncogenes at codons 12, 13, and 61 and the detection of minimal residual neoplastic cells in patients in complete clinical remission. Among many kinds of tumor specific gene translocations, BCR-ABL gene in t(9;22)(q34;q11) and BCL-2-IgH gene in t(14:18)(q32;q21) have been successfully PCR-amplified around their fused regions. In lymphoid malignancies gene rearrangements of T cell receptor chain or immunoglobulin heavy chain can be used as clonal markers for leukemic cells. PCR technique permits the detection of leukemia DNA at dilution of 10(-4) to 10(-6). Although further investigation of patients' follow-up in large scale is needed, this technique seems to hold promise for the monitoring of residual neoplastic cells.
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PMID:[Polymerase chain reaction (PCR)--a novel tool for the molecular diagnosis of neoplasms]. 220 61

We evaluated the effect of various immunosuppressive drugs in the SRC assay. We chose the most appropriate day to obtain the results of the SRC assay using the MBT-2 tumor. MBT-2 tumor-bearing mice of homogenic and heterogenic strains were separately given one of the three: cyclophosphamide, azathioprine or mizoribine. These drugs were evaluated on the 6th and the 11th day for the immunosuppressive effects expected from a host versus graft reaction. Concerning the homogenic mice that were injected with drugs, on the 11th day, the growth of the tumor was favorably suppressed in comparison with the growth of the control group (A-1) due to the anti-tumor effect of immunosuppressive drugs. We concluded that the 6th day was the most, appropriate day to obtain the results of this assay. Concerning the heterogenic mice, similar results were observed. In the mizoribine-group, we subcutaneously injected 200 mg/kg on alternate days. Yet the implanted tumor grew almost at the same rate as that of the A-1 group. In this group, a histological study showed reduction of the tumor cells and few inflammatory cells. We concluded that this drug was more useful than the others in the SRC assay and the suitable day for judgement was the 6th day.
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PMID:[Comparison of the effects of various immunosuppressive drugs on subrenal capsule assay (SRC assay)]. 223 71

Tyrosine phosphorylation is important in the transmission of growth and differentiation signals; known tyrosine kinases include several oncoproteins and growth factor receptors. Interestingly, some differentiated cell types, such as erythrocytes and platelets contain high amounts of phosphotyrosine. We analyzed tyrosine kinases expressed in the K-562 chronic myelogenous leukemia cell line, which has a bipotential erythroid and megakaryoblastoid differentiation capacity. Analysis of 359 polymerase chain reaction-amplified cDNA clones led to the identification of 14 different tyrosine kinase-related sequences (JTK1-14). Two of the clones (JTK2 and JTK4) represent unusual members of the fibroblast growth factor receptor gene family, and the clones JTK5, JTK11, and JTK14 may also belong to the family of receptor tyrosine kinases but lack a close relationship to any known tyrosine kinase. Each of these different genes has its own characteristic expression pattern in K-562 cells and several other human tumor cell lines. In addition, the JTK11 and JTK14 mRNAs are induced during the megakaryoblastoid differentiation of K-562 cells. These tyrosine kinases may have a role in the differentiation of megakaryoblasts or in the physiology of platelets.
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PMID:Putative tyrosine kinases expressed in K-562 human leukemia cells. 224 64

The presence of Philadelphia chromosome t(9:22) is a hallmark of 95% of clinical cases of chronic myelogenous leukemia (CML) as well as 20% of adult acute lymphoblastic leukemia (ALL) and 5% of acute myeloid leukemia (AML). The product of t(9;22) is a fusion protein BCR-ABL. The fusion proteins of CML, ALL and AML have increased tyrosine kinase activity and show a transforming potential in vitro and in animal models. The shorter p190 protein is associated almost only with ALL and AML, while the protein p210 is present in both chronic phase and blast crisis of CML and also in 50% of Philadelphia-positive (Ph1+) ALL. In CML the transition from chronic phase to blast crisis is usually accompanied by additional genetic events, e.g. additional chromosomal abnormalities, and oncogene activation(s). The detailed understanding of molecular basis of CML, and Ph1+ ALL and AML provides highly sensitive molecular and serological methods to complement classical cytogenetics. The advantages and limitations of these techniques are described and discussed below.
Tumour Biol 1990
PMID:Molecular pathology of chronic myelogenous leukemia. 224 53

The 6-day subrenal capsule assay for determining chemotherapeutic sensitivities of brain tumors was studied. Rat glioma 9L and ACNU resistant 9L-2 were transplanted under the renal capsule of normal immunocompetent WKA rats for laboratory investigation. Evaluation of implanted tumor growth till 12 days was performed. The effects of chemotherapeutic agents administered intravenously were evaluated by measuring the growth rate of implanted tumor specimens. The results obtained from SRC were compared with the results from colony forming assay. Both were correlated to each other. On the other hand, histological investigation revealed that implanted human tumor cells had been diminished and implanted tumor was replaced by immunoreactive cells from the host in many cases. These results threw doubt on a reliability of SRC. To avoid this immunoreaction, cyclophosphamide was injected as immunosuppressive agent subcutaneously 24 hours before implantation. In such cases, the growth rates of implanted tumors were increased and histologically the implanted tumor cells existed for 6 days after implantation. Twenty-three malignant brain tumors (malignant astrocytomas 16, metastatic tumors 5, malignant lymphoma 2) were obtained as surgical specimens. Evaluable assay rate of our study were 89%. 15 patients with malignant astrocytomas were studied about correlation between the sensitivities of ACNU and post-operative clinical courses. Overall clinical correlation of 15 cases of malignant astrocytomas was 47%. These results from subrenal capsule assay are not seemed to be beneficial for clinical use. Immunoreactive response when using immunocompetent rats must be solved in future.
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PMID:[Chemotherapy responsiveness of brain tumors in subrenal capsule assay]. 232 45


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