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

Six human colon tumor cell lines were analyzed for their constitutive levels of the c-myc protein. The nuclear proto-oncogene, c-myc, was detected as an expressed product in all of the human colon tumor cell lines analyzed. The poorly differentiated cell lines HCT116, RKO and C showed c-myc levels that averaged 2-fold greater than their well-differentiated counterparts, i.e., GEO, CBS and FET. When c-myc levels and responses to serum induction were analyzed in the presence of inducers of differentiation, i.e., dimethylformamide, retinoic acid, sodium butyrate and TGF-beta, distinct patterns of sensitivity and resistance emerged. Nuclear c-myc levels were reduced in all the colon cell phenotypes treated with dimethylformamide or sodium butyrate. Only the well-differentiated human colon tumor cell lines were responsive to transforming growth factor-beta. Only one of the human colon tumor cell lines (GEO) responded to retinoic acid. Increased levels of c-myc protein were found to correlate well with greater growth rates and with poor differentiation class. Similarly, a parallel sensitivity to down-regulation of c-myc levels and attenuation of c-myc induction curves for inducers of differentiation were observed in growth sensitive human colon tumor cell lines.
 ...
PMID:Sensitivity of nuclear c-myc levels and induction to differentiation-inducing agents in human colon tumor cell lines. 154 Sep 46

There is increasing evidence that urokinase secreted by tumor cells can be bound to a cell surface receptor retaining its full potential to activate plasminogen and subsequently cleave basement membrane constituents. This study was undertaken to discriminate between soluble and cell surface bound urokinase as a potential mediator of in vitro invasion by cultured colon cancer. Extracellular matrix invasion by a colon cancer cell line GEO, characterized as being a poor secretor of urokinase and having few receptors (less than 10(4) receptors/cell) was not augmented when these cells were made to secrete up to 8 times as much urokinase, in response to an exogenous urokinase gene driven by the Rous sarcoma virus long terminal repeat promoter. The majority of the plasminogen activator (greater than 95%) appeared in the culture medium, this reflecting the low numbers of binding sites displayed by GEO cells. In contrast, the cell line HCT 116 equipped with 10 times as many binding sites, (greater than 10(5)/cell), the majority of which are occupied with endogenous ligand, was an efficient invader of the extracellular matrix. Inhibition of urokinase binding to the cell surface receptors using an antibody to the A chain of the plasminogen activator reduced invasion by 65%. The cell line RKO is equipped with 3 x 10(5) receptors/cell, 15% of which are tagged with endogenous urokinase. Pretreatment of these cells with a concentration range of urokinase known to result in the majority of these binding sites being charged with the plasminogen activator led to a dose dependent increase in extracellular matrix invasion. Together, these data suggest that for cultured colon cancer, at least, invasion is a function of the amount of cell surface receptor bound urokinase.
 ...
PMID:Role of the urokinase receptor in facilitating extracellular matrix invasion by cultured colon cancer. 164 43

The effects of vasoactive intestinal polypeptide (VIP) and dibutyryl cyclic adenosine 3':5'monophosphate (dbcAMP) on two human colon carcinoma cell lines, HCT 116 and GEO, were investigated. VIP and dbcAMP inhibited the growth of both cell lines in monolayer culture in a dose-dependent manner. Within 6 h of treatment with 1 mM dbcAMP or 0.3 microM VIP, numerous mucin-like droplets were secreted by GEO cells. VIP and dbcAMP also increased carcinoembryonic antigen (CEA) secretion. In both cell lines, a 9-fold increase in conditioned medium CEA levels was observed at 1 mM dbcAMP and a 2.6-fold increase at 1.5 microM VIP. Time- and concentration-dependent evaluation in cAMP levels were elicited by VIP in the two cell lines. Immunocytochemical studies for cell-surface glycoprotein detection in GEO cells showed that VIP induced a morphological and functional organization of mucin-secreting cells. These results indicate that VIP and dbcAMP have antiproliferative and strong differentiation-promoting effects in colon cancer cells. This is the first report of VIP-induced mucin secretion in colon tumor cells.
 ...
PMID:Promotion of differentiation in human colon carcinoma cells by vasoactive intestinal polypeptide. 254 28

Using an assay based on the binding of a carcinoembryonic antigen (CEA)-specific monoclonal antibody, we have examined the expression of carcinoembryonic antigen genes in human colon tumor and normal fibroblast cell lines. CEA expression was not detectable in the normal fibroblast cell lines, whereas varying levels of high CEA expression were found in the colon tumor cell lines LS-174T, GEO, and WIDR. We have used a 550-base pair CEA probe derived from cloned complementary DNA to carry out Southern analysis of the DNA isolated from the normal and colon tumor cell lines. At high stringency, the CEA probe detected seven BamHI fragments in all DNAs analyzed. At low stringency, however, 14 BamHI fragments ranging from 1.5 to 23 kilobases were detected. Results of the Southern analysis demonstrate no amplification or rearrangement of the CEA genes in tumor cells. We used methylation-sensitive restriction endonucleases, HpaII and HhaI, to compare the degree of methylation of CEA family of genes in normal and colon tumor cell lines. Our results demonstrate that the CEA family of genes exists in a state of hypermethylation in the normal cell lines. In contrast, the CEA gene(s) are relatively hypomethylated in the tumor cell lines, suggesting a correlation between the state of methylation and degree of expression of the CEA gene(s). A comparison of the state of methylation of the CEA gene(s) in cells before and after treatment with the gamma-interferon (which up-regulates CEA steady-state mRNA levels) showed no detectable difference in the degree of DNA methylation. The segments of CEA genes that are hypermethylated in normal cells, but are hypomethylated in tumor cells, were also identified. Thus, these studies may help identify the sites of methylation that are crucial for the control of CEA gene regulation.
 ...
PMID:Correlation of DNA hypomethylation with expression of carcinoembryonic antigen in human colon carcinoma cells. 316 26

The plasminogen activator urokinase promotes tumor invasion by converting plasminogen into plasmin, which degrades several extracellular matrix components. Urokinase can bind to a specific cell surface receptor, which leads to accelerated plasmin production. While there is good evidence indicating a role for this binding site in tumor invasion/metastasis, there is little information concerning the regulation of urokinase receptor expression in invasive cancer. To address this question a series of colon cancer cell lines, which demonstrate either a high or low ability to invade an extracellular matrix-coated porous filter, was characterized for receptor expression at the transcriptional and post-transcriptional levels. The invasive cell lines possessed 10-fold more receptors than their non-invasive counterparts as shown by cross-linking experiments and by Western blotting. Northern blotting indicated that this disparity in receptor number could be largely accounted for by a different amount of steady-state mRNA encoding the binding site. However, neither gene amplification nor enhanced mRNA stability could account for the augmented receptor protein observed for the invasive colon cancer cell types. In contrast, nuclear run-on experiments with representative cell lines revealed that the 10-fold difference in receptor display between the invasive-competent and invasive-deficient cells could be largely accounted for by differences in transcription rates. Transcription of the u-PAR gene in the receptor-deficient GEO cells, but not in the receptor-rich RKO cells, could be augmented by protein kinase C stimulation. These findings provide a clear rationale for studies to determine if the urokinase receptor promoter in invasive colon cancer is activated in cis or in trans.
 ...
PMID:Transcriptional activation of the urokinase receptor gene in invasive colon cancer. 807 48

It has been reported that HLA-DR is a potent inducer of thrombin generation. Human colorectal cells (GEO, WiDr, DLD-1, and MIP) that lack the constitutive expression of HLA-DR cause platelet aggregation through a thrombin-dependent mechanism. Treatment with recombinant human gamma-interferon induced the expression of HLA-DR in the GEO, WiDr, and DLD-1 cells, whereas the MIP cell line remained HLA-DR negative. The concurrent analysis of tumor cell/platelet interaction after gamma-interferon treatment showed a decrease in platelet proaggregating activity of either the responsive GEO (highly expressing HLA-DR) or the unresponsive MIP (HLA-DR negative) cells. Furthermore, the DLD-1 (moderately expressing HLA-DR) cells showed an increase of proaggregating activity after gamma-interferon treatment, whereas WiDr (highly expressing HLA-DR) cells did not modify their activity. These results suggest a lack of a role of HLA-DR in the in vitro platelet proaggregating activity of human colorectal tumor cells.
 ...
PMID:Evaluation of the potential role of class II histocompatibility antigen HLA-DR in platelet/tumor cell interaction. 830 20

Alleviation of tumor-related symptoms may be a more appropriate basis for judging drug efficacy in pancreatic cancer than is tumor shrinkage. Clinical benefit response (CBR), a new way to assess clinical efficacy based on marked, sustained improvement in pain intensity, analgesic consumption, and performance status, was used to evaluate a new chemotherapeutic agent, gemcitabine (2',2'-difluorodeoxycytidine [Gemzar]). A phase III study of newly diagnosed pancreatic cancer patients treated with either gemcitabine or fluorouracil (5-FU) and a phase II trial of gemcitabine in patients whose disease had progressed despite prior treatment with 5-FU both demonstrated that a significant number of patients achieved a CBR with gemcitabine. Prolonged survival was a secondary benefit demonstrated in the phase III trial. In both studies, gemcitabine was well tolerated, with a relatively mild toxicity profile. These results suggest that gemcitabine may serve as a prototype for the development of more effective therapies for pancreatic cancer patients.
 ...
PMID:New developments in chemotherapy for patients with advanced pancreatic cancer. 888 3

Human colon tumor cell lines that were adapted to grow in chemically defined medium were tested for their growth sensitivity to exogenous transferrin, insulin, and epidermal growth factor (EGF). Less differentiated cell lines, C and HCT116, were able to grow in the presence of a single peptide supplement, to respond synergistically to transferrin and insulin in combination, and to be insensitive to supplementation with exogenous EGF. The more differentiated cell lines, CBS and GEO, were found to respond to exogenous EGF in a concentration-dependent manner, to require at least two peptide factor supplements to support growth, and to respond synergistically when EGF was added to chemically defined medium that already contained transferrin and insulin. To investigate whether changes in the number or the affinity-classes of the EGF-receptor might be involved in any of these growth responses, changes in EGF-receptor number and dissociation constant were determined as a function of cell growth condition. The poorly differentiated HCT cell line HCT116 was found to undergo 28 to 64% increases in [125I]EGF-binding when its medium was supplemented with transferrin, insulin, or transferrin plus insulin. The more differentiated CBS cell line responded to all peptide supplements with decreases in [125I]EGF-binding ranging from 12 to 73%. These findings indicate that the actions of transferrin and insulin are fundamental to the growth regulatory mechanisms of these two differentiation classes of human colon tumor cell lines, but that their mechanisms are different.
 ...
PMID:Transferrin and insulin enhance human colon tumor cell growth by differentiation class specific mechanisms. 893 90

2',2'-difluorodeoxycytidine (LY 188011, Gemcitabine, Gemzar) has recently been approved both in Europe for the treatment of patients with non-small cell lung cancer and in the United States for patients with pancreatic cancer. Since the initial discovery of the compound, we have been evaluating the in vitro activity of gemcitabine against human tumor colony-forming units taken directly from patients and growing in soft agar (in the human tumor cloning assay-HTCA). A total of 315 specimens have had gemcitabine tested against them with 44% giving evaluable results. Gemcitabine has been found to be active against colony-forming units from patients with non-small cell lung, breast, ovarian, and pancreatic cancers. A concentration-dependent in vitro response was noted with a higher in vitro response rate noted at 20 micrograms/ml than at 2.0 micrograms/ml. Based on subsequent clinical phase II data, the HTCA correctly predicted the wide spectrum of the clinical activity of gemcitabine.
 ...
PMID:Activity of gemcitabine in a human tumor cloning assay as a basis for clinical trials with gemcitabine. San Antonio Drug Development Team. 895 81

We have demonstrated that anti-sense phosphorothioate oligodeoxynucleotides (AS S-oligos) directed against the EGF-like growth factors CRIPTO (CR), amphiregulin (AR) or transforming-growth-factor-alpha(TGFalpha) mRNA, are equipotent in their ability to inhibit the growth of human colon-carcinoma GEO cells. In this study, we evaluated the effect of combinations of these AS S-oligos and conventional anti tumor drugs, such as 5-fluorouracil (5-FU), adriamycin (ADR), mitomycin C (MIT) and cis-platinum (CDDP), on GEO cell growth. Dose-dependent growth inhibition was observed by treatment either with AS S-oligos or with anti-tumor drugs, using a clonogenic assay. Furthermore, an additive growth inhibitory effect occurred when GEO cells were exposed to the AS S-oligos after treatment with different concentrations of either 5-FU, MIT, ADR or CDDP. For example, treatment of GEO cells with a combination of low concentrations of 5-FU and any of the 3 AS S-oligos resulted in up to 70% growth inhibition. However, treatment of GEO cells with AS S-oligos before exposure to 5-FU or CDDP resulted in reduced efficacy of both drugs. Flow-cytometric analysis of DNA content demonstrated that treatment with the AS S-oligos caused a slight reduction of the percentage of cells in the S-phase of the cell cycle. These data suggest that combinations of AS S-oligos directed against EGF-related growth factors and of conventional anti-tumor drugs may result in efficient inhibition of colon-carcinoma cell growth.
 ...
PMID:Anti-sense oligonucleotides directed against EGF-related growth factors enhance anti-proliferative effect of conventional anti-tumor drugs in human colon-cancer cells. 933 55


1 2 3 4 5 6 7 8 9 10 Next >>