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Query: UMLS:C0699790 (colon cancer)
 28,837 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1,2-Dimethylhydrazine, in weekly subcutaneous (s.c.) doses of 20 mg/kg body weight, produces colonic tumors in virtually 100% of rodents, with a latency period of approximately 6 months. To determine whether alterations in Na+-H+ exchange existed before the development of dimethylhydrazine-induced colon cancer, rats were given s.c. injections of this agent (20 mg/kg body wt. per per week) or diluent for 5 weeks. Animals were then killed, rat colonic brush-border membrane vesicles prepared and amiloride-sensitive sodium-stimulated proton efflux was measured and compared in control and treated-preparations. The results of these studies demonstrated that dimethylhydrazine treatment: (1) significantly increased the Vmax of this exchange without altering the Km for sodium of this exchange process, utilizing the fluorescent pH-sensitive dye, acridine orange; 22Na flux experiments also demonstrated an increase in amiloride-sensitive proton-stimulated sodium influx across treated-membrane vesicles; (2) did not appear to significantly influence Na+ permeability or proton conductance in treated-preparations compared to their control counterparts; and (3) did not significantly affect the kinetic parameters of amiloride-sensitive sodium-stimulated proton efflux in renal cortex brush-border membrane vesicles using acridine orange. This data, therefore, suggests that alterations in Na+-H+ exchange in rat colonic brush-border membranes may be involved in the malignant transformation process induced by this procarcinogen in the large intestine.
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PMID:1,2-Dimethylhydrazine-induced alterations in Na+-H+ exchange in rat colonic brush-border membrane vesicles. 283 82

Modal DNA (ploidy) and sensitivity of DNA in situ to denaturation by acid have been analyzed by flow cytometry of 10 colorectal adenomas and 35 adenocarcinomas; 39 normal mucosa samples served as controls. A new method was developed to denature DNA in chromatin of the freshly isolated, intact, and unfixed individual cell nuclei from surgically resected material. The sensitivity of DNA denaturation (T alpha) was assayed by metachromatic staining with acridine orange and calculated as a ratio of the alpha t index of the tumor sample to the alpha t index of normal mucosa; the alpha t index is that fraction of DNA, following treatment at pH 1.4, that stains metachromatically with acridine orange at pH 2.6. All adenomas were diploid and in nine of 10 the T alpha value was close to 1.00, indicating no difference from control specimens in DNA sensitivity to denaturation. Forty-nine% of adenocarcinomas were aneuploid. Forty-six% of adenocarcinomas differed from normal in sensitivity of DNA to denaturation; the T alpha value was lower than 0.90 indicating that chromatin of the tumor cells was more resistant to denaturation than control cells. There was no correlation between sensitivity to denaturation of DNA and incidence of aneuploidy. However, there was a correlation between T alpha and the pathologically determined stage of disease. There was increased resistance to denaturation in 58% of tumors classified as Dukes' C/D stage, in 36% of tumors classified as Dukes' B, and in 20% classified as Dukes' A stage of the disease. Statistical analysis of these results revealed significant differences between distributions of T alpha in noninvasive (Adenomas and Dukes' A) versus invasive (Dukes' B and C/D) tumors with level of significance at P = 0.02. The data suggest that acid denaturation of DNA in situ may be a valuable adjunct in assessing the biology of colon cancer. The molecular basis for this phenomenon is discussed.
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PMID:DNA in situ sensitivity to denaturation: a new parameter for flow cytometry of normal human colonic epithelium and colon carcinoma. 360 42

A series of bifunctional ligands has been developed as prototype DNA-binding combilexins using a DNA template-directed approach. These novel agents contain a 1,3-diaryltriazene linker moiety, present in the established DNA minor groove-binder berenil [1,3-bis(4'-amidinophenyl)-triazene], which is attached to an intercalating acridine chromophore by a functionalized thiazole residue. This 9-arylacridine is predicted to confer rotational freedom to the hybrid molecule and thus facilitate bifunctional interaction with double-stranded DNA through a combination of 'classical' intercalation and minor groove-binding processes. The noncovalent DNA-binding properties of these acridine-triazene combilexins, together with the component molecular fragments, have been examined by fluorescence quenching and thermal denaturation studies with calf thymus DNA and two oligonucleotides, [poly(dA-dT)]2 and [poly(dG-dC)]2. In addition, the binding behaviors of these acridine compounds are compared to those of proflavine (3,6-diaminoacridine) and its 9-phenyl derivative. The results indicate that the hybrid agents (i) are more DNA-affinic than either molecular component, (ii) retain the AT-preferential binding properties of the parent difunctionalized 1,3-diaryltriazene residues, despite weak GC-preferential behavior associated with the acridine chromophore, and (iii) have a reduced binding affinity at pH 7 that reflects the protonation status of the acridine. In contrast, the more basic proflavines show much greater binding affinity and a marked preference for GC-rich DNA sequences. In vitro cytotoxicity data with L1210 mouse leukemia and A2780 human colon cancer cell lines show that the conjugate molecules are approximately 10-40-fold more potent than the acridine or triazene subunits and have activities that compare favorably with those of other reported synthetic combilexins. Intercalative binding modes with a model d(GATACGATAC).d(GTATCGTATC) target duplex have been investigated using molecular modeling techniques. These studies provide a rational basis for the binding properties and suggest that the prototype combilexins can bind in a bimodal manner that induces little distortion of the host DNA duplex. Energy-minimized models for the possible dual interactions are discussed.
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PMID:Novel acridine-triazenes as prototype combilexins: synthesis, DNA binding, and biological activity. 765 36

Cell-matrix interactions have important effects on phenotypic features, such as morphology, differentiation and cell growth. Several papers have suggested that when cell-matrix interaction is interrupted, cells grow as multicellular spheroids and eventually undergo apoptosis. We found that when ET(-), a laminin non-adherent colon cancer cell line, was cultured on poly-2-hydroxyethyl methacrylate (HEMA) coated plastic, the cells floated as cellular aggregates of spheroids or as single cells. Some of the single cells contained large intracytoplasmic lumens (ICL) and appeared similar to signet ring cells. These ICL were lined by a layer of short microvilli. The number of the cell did not increase when cultured on poly-HEMA. Another type of single cells, usually without ICL, demonstrated the characteristics of apoptotic cells by histologic examination. Acridine orange staining, flow cytometry and electron microscopy confirmed the apoptotic nature of those cells. On immunohistochemical staining for proliferating cell nuclear antigen, spheroids of cells and single cells with ICL were immunoreactive, while most of the single cells without ICL were negative. These results suggest that multicellular aggregates and formation of ICL were induced by the adaptation of ET(-) colon cancer cells in a harmful environment caused by reduced adhesiveness, and these changes might be related to cell survival.
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PMID:Development of intracytoplasmic lumens in colon cancer cells cultured on non-adhesive surface. 1004 9

Cleavage of poly(ADP-ribose) polymerase (PARP) by caspases is a prominent characteristic of apoptosis or programmed cell death shown to be induced by topoisomerase (Topo) inhibitors. Because Topo I inhibitors have been shown to be effective in the treatment of some patients with colon cancer, we considered the possibility of using PARP cleavage as an early predictor of responsiveness to this class of agents. We show cleavage of PARP in response to treatment with Topo I inhibitors in colon cancer both in vitro and in vivo: (a) in vitro in SW480, HCT116, VACO5, VACO6, VACO8, VACO411, VACO425, and VACO451 human colon cancer cell lines treated with topotecan (TPT) or CPT-11; (b) in vivo in SW480, VACO451, and VRC5 colon cancer xenografts grown in athymic mice treated with TPT or CPT-11; and (c) in vivo in colon cancer samples from patients undergoing a Phase II clinical trial with CPT-11. Our results show a strong correlation between percentage of PARP cleavage and percentage of acridine orange-positive cells in colon cancer cell lines treated with 0.1 microM TPT for 24 and 48 h, confirming that PARP cleavage is a useful marker for programmed cell death in colon cancer cell lines. Results from experiments performed on colon cancer xenografts also show an association between PARP cleavage and response to treatment with TPT or CPT-11. The increase of PARP cleavage in xenografts and in clinical samples corresponding to treatment with Topo I inhibitors suggests that this procedure may have early predictive value to assess effectiveness of treatment. These results provide the basis for determining the validity of using PARP cleavage as an early marker of chemotherapeutic effectiveness in human samples.
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PMID:Detection of poly(ADP-ribose) polymerase cleavage in response to treatment with topoisomerase I inhibitors: a potential surrogate end point to assess treatment effectiveness. 1010 Jul 20

Cell-matrix interactions have important effects on phenotypic features, such as morphology, differentiation and cell growth. Several papers have suggested that when cell-matrix interactions are interrupted, cells grow as multicellular spheroids and eventually undergo apoptosis. We found that when ET(-), a laminin non-adherent colon cancer cell line, was cultured on poly-2-hydroxyethyl methacrylate (HEMA) coated plastic, the cells floated as cellular aggregates of spheroids or as single cells. Some of the single cells contained a very large intracytoplasmic lumen (ICL) and appeared similar to signet ring cells. These ICL were lined by a layer of short microvilli. The number of the cell did not increased cells when cultured on poly-HEMA. Another type of single cells, usually without ICL, demonstrated the characteristics of apoptotic cells by histologic examination. Acridine orange staining, flow cytometry and electron microscopy confirmed the apoptotic nature of those cells. In immunohistochemical staining for proliferating cell nuclear antigen, spheroids of cells and single cells with ICL were immunoreactive, while most of the single cells without ICL were negative. These results suggest that multicellular aggregation and formation of ICL were induced by the adaptation of ET(-) colon cancer cells in a harmful environment caused by reduced adhesiveness, and these changes might be related to cell survival.
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PMID:Development of intracytoplasmic lumens in a colon cancer cell line cultured on a non-adhesive surface. 1073

The present study was undertaken to determine if (a) genistein induces topo II-mediated DNA damage in HT-29 colon cancer cells; and (b) if this damage is required to induce apoptosis. DNA damage was evaluated using the comet assay. Apoptosis was determined by the ethidium bromide/acridine orange staining technique. DNA breakage was noted within 1 h of treatment. Apoptosis was only induced with high concentrations (>/=60 microM) of genistein. Marked inhibition of HT-29 cell growth was evident at concentrations ranging from 60 to 150 microM. This was associated with a cell cycle arrest at G(2)/M. Similar findings were obtained in SW-620 and SW-1116 colon cancer cell lines. Aclarubicin, a topo II antagonist, reduced genistein-induced DNA breaks but did not reduce apoptosis. These data suggest that, in colon cancer cells, topo II serves as the enzymatic target of genistein. Furthermore, topo II-mediated DNA cleavage is not required for the induction of apoptosis.
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PMID:Genistein induces apoptosis and topoisomerase II-mediated DNA breakage in colon cancer cells. 1076 54

Sangre de grado is an ethnomedicinal red tree sap obtained from Croton spp. that is used to treat gastrointestinal ulcers, cancer and to promote wound healing. To evaluate the potential role of sangre de grado (SdG) in cancer we examined its effects on human cancer cells, AGS (stomach), HT29 and T84 (colon). Viability of cells treated with SdG (10-200 microg/ml) decreased (P<0.01) in a dose dependent manner measured over a 24-h period. Cell proliferation at 48 h decreased (P<0.01) in all cells treated with SdG (>100 microg/ml). When cells in suspension were treated with SdG (100 microg/ml) cell adherence was severely compromised (>85%). Cells treated with SdG (100 microg/ml) underwent apoptosis as detected by nucleus condensation and DNA fragmentation determined by ELISA, and flow cytometry. Morphological changes as assessed by acridine orange. These effects were similar to that observed with Taxol (30 microM). A significant alteration of microtubular architecture was equally observed in both stomach and colon cancer cells exposed to SdG (100 microg/ml). The induction of apoptosis and microtubule damage in AGS, HT29 and T84 cells suggest that sangre de grado should be evaluated further as a potential source of anti-cancer agents.
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PMID:Sangre de grado Croton palanostigma induces apoptosis in human gastrointestinal cancer cells. 1200 1

As previously demonstrated, deguelin [(7aS, BaS)-13, 13a-dihydro-9,10-dimethoxy-3,3-dimethyl-3H-bis[1]benzo-pyrano[3,4-b:6',5'-e]pyran-7(7aH)-one mediates anti-proliferative properties in a variety of cell types. In the present study, deguelin was found to suppress the growth of HT-29 colon cancer cells with an IC(50) of 4.32 x 10(-8) M. The cells were arrested in the G1-S-phase of the cycle. Investigations of G1/S regulatory proteins by Western blot analyses showed an upregulation of p27, and decreased expression levels of cyclin E and CDK4. Furthermore, by 24 h, exposure to deguelin resulted in an increase in the hypophosphorylated form of Rb. Since hypophosphorylated pRb binds to and inactivates E2F1, additional studies were performed and downregulation of E2F1 was observed after 24 h of treatment with deguelin. These results are consistent with the observation that deguelin arrested cells in the G1-S- phase. In addition, based on ethidium bromide/acridine orange staining, detection of digoxigenin-labelled genomic 3'-OH DNA ends, and DNA laddering, it was found that deguelin exerts its growth inhibitory effects via the induction of apoptosis. Based on these data, the potential of deguelin to serve as a cancer chemotherapeutic agent for colon cancer may be suggested.
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PMID:Deguelin inhibits the growth of colon cancer cells through the induction of apoptosis and cell cycle arrest. 1246 Jul 90

We have shown that genistein, a major component of soy, has anti-colon cancer effects in vitro. These effects are attainable at high concentrations that are difficult to achieve in the serum. The purpose of this study was to enhance the activity of genistein against colon cancer cells by coupling it to 17.1A. The monoclonal antibody 17.1A recognizes an epithelial membrane antigen that is overexpressed in colon cancer. Synthesis of Gen-17.1A was achieved by photochemical conjugation using sulfa-SANPAH. Its purity was evaluated by SDS-PAGE. Binding of Gen-17.1A to SW-620 and HT-29 cells was shown using flow cytometry. Internalization was demonstrated by FITC-labeling. Gen-17.1A induced apoptosis in colon cancer cells as evidenced by the acridine orange/ethidium bromide staining method. Gen-17.1A significantly inhibited colon cancer cell growth in vitro and in vivo. Our findings suggest that conjugating genistein to 17.1A monoclonal antibody enhances its effects against colon cancer cells.
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PMID:Targeting colon cancer cells with genistein-17.1A immunoconjugate. 1268 59


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