Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0699790 (colon cancer)
 28,837 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Prodigiosin (PG) is a bacterial red pigment with interesting immunosuppressive and apoptotic properties that have been partly attributed to its ability to uncouple V-ATPase through the promotion of the H+/Cl- symporter. In the present study, we investigate the effect of non-apoptotic concentrations of PG on the lysosomal-pH and on cell cycle progression in colon cancer cells. Lysosomal-pH was tested in DLD-1 cells using acridine orange vital staining. Orange granules, indicative of acidified lysosomes, decreased significantly in cells treated with 25 nM of PG for 1/2 h, and disappeared completely at 100 nM. This suggests that PG can induce lysosomal alkalinization without any apparent cytotoxic effect. Cell cycle progression was analysed in HT29 cells and we found that PG induces a blockage in the G1 phase. This blockage correlates with p21(WAF1/CIP1) induction, and it can be triggered either dependently or independently of p53. In conclusion, the reversible increase in lysosomal-pH and cytosol acidification induced by non-apoptotic concentrations of PG in colon cancer cells, suggests that the apoptotic process induced by PG can not be solely explained by changes in intracellular pH. The effect of intracellular acidification on cell cycle arrest must be analysed more exactly.
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PMID:Non-apoptotic concentrations of prodigiosin (H+/Cl- symporter) inhibit the acidification of lysosomes and induce cell cycle blockage in colon cancer cells. 1612 33

Mouse genetic models that probe important pathways in intestinal cell maturation, such as cell-cycle regulation, apoptosis, and, especially, lineage specific differentiation, have provided profound insight into the underlying mechanisms of intestinal tumor formation and progression. However, a wealth of epidemiological and experimental data indicates that environment, especially the diet, is a principal determinant of relative risk for tumor development. We have demonstrated that even in mouse models in which tumor incidence is strongly initiated by genetic manipulation of genes, such as Apc, p21(WAF1/cip1), and p27(Kip1), a Western-style diet that is high in fat and low in calcium and vitamin D can dramatically increase and accelerate tumor formation. Moreover, experiments show that modulation of calcium and vitamin D levels can substantially influence tumor formation in both the mouse genetic models, as well as in a new dietary model that appears to mimic the development of sporadic colon cancer. Finally, analysis of gene expression profiles provides important insights into how diets may alter metabolic profiles and regulatory pathways that influence probability of tumor formation in the histologically and physiologically normal intestinal mucosa.
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PMID:Dietary components modify gene expression: implications for carcinogenesis. 1625 35

Sulforaphane (SFN) is an isothiocyanate from broccoli that induces phase 2 detoxification enzymes. We recently reported that SFN acts as a histone deacetylase (HDAC) inhibitor in human colon cancer cells in vitro, and the present study sought to extend these findings in vivo. In mice treated with a single oral dose of 10 mumol SFN, there was significant inhibition of HDAC activity in the colonic mucosa after 6 h, and immunoblots revealed a concomitant increase in acetylated histones H3 and H4, which returned to control levels by 48 h. Longer-term treatment with SFN in the diet resulted in levels of acetylated histones and p21(WAF1) in the ileum, colon, prostate, and peripheral blood mononuclear cells that were elevated compared with controls. Consistent with these findings, SFN suppressed tumor development in Apc(min) mice, and there was an increase in acetylated histones in the polyps, including acetylated histones specifically associated with the promoter region of the P21 and bax genes. These results provide the first evidence for HDAC inhibition by SFN in vivo and imply that such a mechanism might contribute to the cancer chemoprotective and therapeutic effects of SFN, alone or in combination with other HDAC inhibitors currently undergoing clinical trials.
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PMID:Sulforaphane inhibits histone deacetylase in vivo and suppresses tumorigenesis in Apc-minus mice. 1640 54

The simple ganglioside GM3 has been shown to have anti-proliferative effects in several in vitro and in vivo cancer models. Although the exogenous ganglioside GM3 has an inhibitory effect on cancer cell proliferation, the exact mechanism by which it prevents cell proliferation remains unclear. Previous studies showed that MDM2 is an oncoprotein that controls tumorigenesis through both p53-dependent and p53-independent mechanisms, and tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN), a dual-specificity phosphatase that antagonizes phosphatidylinositol 3-kinase (PI-3K)/AKT signaling, is capable of blocking MDM2 nuclear translocation and destabilizing the MDM2 protein. Results from our current study show that GM3 treatment dramatically increases cyclin-dependent kinase (CDK) inhibitor (CKI) p21(WAF1) expression through the accumulation of p53 protein by the PTEN-mediated inhibition of the PI-3K/AKT/MDM2 survival signaling in HCT116 colon cancer cells. Moreover, the data herein clearly show that ganglioside GM3 induces p53-dependent transcriptional activity of p21(WAF1), as evidenced by the p21(WAF1) promoter-driven luciferase reporter plasmid (full-length p21(WAF1) promoter and a construct lacking the p53-binding sites). Additionally, ganglioside GM3 enhances expression of CKI p27(kip1) through the PTEN-mediated inhibition of the PI-3K/AKT signaling. Furthermore, the down-regulation of the cyclin E and CDK2 was clearly observed in GM3-treated HCT116 cells, but the down-regulation of cyclin D1 and CDK4 was not. On the contrary, suppression of PTEN levels by RNA interference restores the enhanced expression of p53-dependent p21(WAF1) and p53-independent p27(kip1) through inactivating the effect of PTEN on PI-3K/AKT signaling modulated by ganglioside GM3. These results suggest that ganglioside GM3-stimulated PTEN expression modulates cell cycle regulatory proteins, thus inhibiting cell growth. We conclude that ganglioside GM3 represents a modulator of cancer cell proliferation and may have potential for use in colorectal cancer therapy.
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PMID:Ganglioside GM3 modulates tumor suppressor PTEN-mediated cell cycle progression--transcriptional induction of p21(WAF1) and p27(kip1) by inhibition of PI-3K/AKT pathway. 1657 13

Heme oxygenase-1 can play a protective role against cellular stress. In colon cancer cells, these effects would be relevant to oncogenesis and resistance to chemotherapy. The aim of the study was to examine the effects of heme oxygenase-1 induction on cell survival in a human colon cancer cell line, Caco-2. Serum deprivation induced apoptosis, reduced Akt and p38 phosphorylation, and increased p21(Cip/WAF1) levels. Heme oxygenase-1 induction by treatment with cobalt protoporphyrin IX resulted in resistance to apoptosis, activation of Akt, reduction in p21(Cip/WAF1) levels and modification of bcl2/bax ratio towards survival. Indomethacin reduced apoptosis but in contrast to heme oxygenase-1, arrested cells in G0/G1. Apoptosis was also inhibited by the heme oxygenase metabolites bilirubin and biliverdin but the CO donor tricarbonyldichlororuthenium(II) dimer did not exert significant effects. Protection against apoptosis in cells treated with cobalt protoporphyrin IX was reverted by incubation with heme oxygenase-1 small interfering RNA. This study shows an antiapoptotic effect of heme oxygenase-1 in colon cancer cells which could be mediated by the formation of bilirubin and biliverdin. Our results support an antiapoptotic role for HO-1 in these cells and provide a mechanism by which overexpression of HO-1 may promote tumor resistance to stress in conditions of limited nutrient supply. We have extended these observations by demonstrating that these effects are independent of p38 but are mediated via Akt pathway.
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PMID:Heme oxygenase-1 inhibits apoptosis in Caco-2 cells via activation of Akt pathway. 1669 92

The aim of this study was to analyze the molecular mechanism of inositol hexaphosphate (InsP(6)) action through which it may inhibit proliferation of colon cancer cells and cell cycle progression. A kinetic study of p53 and p21(WAF1) mRNA increase was performed on human colon cancer HT-29 cells after treatment with 1, 5 and 10 mM InsP(6) for 6, 12, 24 and 48 h. Real-time-QPCR based on TaqMan methodology was applied to analyze quantitatively the transcript levels of these genes. The transcription of beta-actin and GAPDH genes was assessed in parallel to select the control gene with least variability. The 2(-Delta Delta Ct) method was used to analyze the relative changes in gene transcription. InsP(6) stimulated p53 and p21(WAF1) expression at the mRNA level, with the highest increase in p21(WAF1) mRNA occurring at 24 h, i.e., following the highest increase in p53 mRNA observed at 12 h. Based on these studies it may be concluded that the ability of InsP(6) to arrest the cell cycle may be mediated by the transcriptional up-regulation of the p53-responsive p21(WAF1) gene.
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PMID:Quantitative analysis of the level of p53 and p21(WAF1) mRNA in human colon cancer HT-29 cells treated with inositol hexaphosphate. 1673 61

Extracts of Aesculus hippocastanum (horse chestnut) seed have been used in the treatment of chronic venous insufficiency, edema, and hemorrhoids. Most of the beneficial effects of horse chestnut are attributed to its principal component beta-escin or aescin. Recent studies suggest that beta-escin may possess anti-inflammatory, anti-hyaluronidase, and anti-histamine properties. We have evaluated the chemopreventive efficacy of dietary beta-escin on azoxymethane-induced colonic aberrant crypt foci (ACF). In addition, we analyzed the cell growth inhibitory effects and the induction of apoptosis in HT-29 human colon cancer cell line. To evaluate the inhibitory properties of beta-escin on colonic ACF, 7-week-old male F344 rats were fed experimental diets containing 0%, 0.025%, or 0.05% beta-escin. After 1 week, the rats received s.c. injections of azoxymethane (15 mg/kg body weight, once weekly for 2 weeks) or an equal volume of normal saline (vehicle). Rats were continued on respective experimental diets and sacrificed 8 weeks after the azoxymethane treatment. Colons were evaluated histopathologically for ACF. Administration of dietary 0.025% and 0.05% beta-escin significantly suppressed total colonic ACF formation up to approximately 40% (P < 0.001) and approximately 50% (P < 0.0001), respectively, when compared with control diet group. Importantly, rats fed beta-escin showed dose-dependent inhibition (approximately 49% to 65%, P < 0.0001) of foci containing four or more aberrant crypts. To understand the growth inhibitory effects, HT-29 human colon carcinoma cell lines were treated with various concentrations of beta-escin and analyzed by flow cytometry for apoptosis and cell cycle progression. Beta-escin treatment in HT-29 cells induced growth arrest at the G1-S phase, which was associated with the induction of the cyclin-dependent kinase inhibitor p21(WAF1/CIP1), and this correlated with reduced phosphorylation of retinoblastoma protein. Results also indicate that beta-escin inhibited growth of colon cancer cells with either wild-type or mutant p53. This novel feature of beta-escin, a triterpene saponin, may be a useful candidate agent for colon cancer chemoprevention and treatment.
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PMID:Beta-escin inhibits colonic aberrant crypt foci formation in rats and regulates the cell cycle growth by inducing p21(waf1/cip1) in colon cancer cells. 1681 4

In this paper, we will outline the current understanding of cell cycle modulation and induction of apoptosis in cancer cells by natural and synthetic bile acid. Bile acid homeostasis is tightly regulated in health, and their cellular and tissue concentrations are restricted. However, when pathophysiological processes impair their biliary secretion, hepatocytes are exposed to elevated concentrations of bile acids which trigger cell death. In this context, we developed several newly synthesized bile acid derivatives. These synthetic bile acids modulated the cell cycle and induced apoptosis in several human cancer cells similar to natural bile acids. In human breast and prostate cancer cells with different tumor suppressor p53 status, synthetic bile acid-induced growth inhibition and apoptosis were associated with up-regulation of Bax and p21(WAF1/CIP1) via a p53-independent pathway. In Jurkat human T cell leukemia cells, the synthetic bile acids induced apoptosis through caspase activation. In addition to this, the synthetic bile acids induced apoptosis in a JNK dependent manner in SiHa human cervical cancer cells, via induction of Bax and activation of caspases in PC3 prostate cancer cells and induction of G1 phase arrest in the cell cycle in HT29 colon cancer cells. Moreover, they induced apoptosis in four human glioblastoma multiform cell lines (i.e., U-118MG, U-87MG, T98G, and U-373MG) and one human TE671 medulloblastoma cells. In addition to this, a chenodeoxycholic acid derivative, called HS-1200, significantly decreased the growth of TE671 medulloblastoma tumor size and increased life span in non-obese diabetic and severe combined immunodeficient (NOD/SCID) mice. Therefore, these new synthetic bile acids, which are novel apoptosis mediators, might be applicable to the treatment of various human cancer cells.
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PMID:Modulation of the cell cycle and induction of apoptosis in human cancer cells by synthetic bile acids. 1716 73

We have recently shown that thymoquinone (TQ) is an antineoplastic drug that induces p53-dependent apoptosis in human colon cancer cells. This study evaluated the antiproliferative and pro-apoptotic effects of TQ in two human osteosarcoma cell lines with different p53 mutation status. TQ decreased cell survival dose-dependently and, more significantly, in p53-null MG63 cells (IC(50) = 17 muM) than in p53-mutant MNNG/HOS cells (IC(50) = 38 muM). Cell viability was reduced more selectively in MG63 tumor cells than in normal human osteoblasts. Flow cytometric analysis showed that TQ induced a much greater increase in the PreG(1) (apoptotic) cell population, but no cell cycle arrest in MG63. G(2)/M arrest in MNNG/HOS cells was associated with p21(WAF1) upregulation. Using three DNA damage assays, TQ was confirmed to result in a significantly greater extent of apoptosis in p53 null MG63 cells. Although the Bax/Bcl-2 ratios were not differentially modulated in both cell lines, the mitochondrial pathway appeared to be involved in TQ-induced apoptosis in MG63 by showing the cleavage of caspases-9 and -3. Oxidative stress and mitochondrial O(2)(*-) generation in isolated rat mitochondria were enhanced by TQ as measured by the dose-dependent reduction in aconitase enzyme activity and Amplex Red oxidation respectively. TQ-induced oxidative damage, reflected by an increase in gamma-H2AX foci and increased protein expression levels of gamma-H2AX and the DNA repair enzyme, NBS1, was more pronounced in MNNG/HOS than in MG63. We suggest that the resistance of MNNG/HOS cells to drug-induced apoptosis is caused by the up-regulation of p21(WAF1) by the mutant p53 (transcriptional activity was shown by p53 siRNA treatment) which induces cell cycle arrest and allows to repair DNA damage. Collectively, these findings show that TQ induces p53-independent apoptosis in human osteosarcoma cells. As the loss of p53 function is frequently observed in osteosarcoma patients, our data suggest the potential clinical usefulness of TQ for the treatment of these malignancies.
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PMID:Lack of p53 augments thymoquinone-induced apoptosis and caspase activation in human osteosarcoma cells. 1721 78

Oxaliplatin (OHP) is an anticancer agent that acts by formation of Platinum-DNA (Pt-DNA) adducts resulting in DNA-strand breaks and is used for the treatment of colorectal cancer. The pyrimidine analog trifluorothymidine (TFT) forms together with a thymidine phosphorylase inhibitor (TPI) the anticancer drug formulation TAS-102, in which TPI enhances the bioavailability of TFT in vivo. In this in vitro study the combined cytotoxic effects of OHP with TFT were investigated in human colorectal cancer cells as a model for TAS-102 combinations. In a panel of five colon cancer cell lines (WiDr, H630, Colo320, SNU-C4 and SW1116) we evaluated the OHP-TFT drug combinations using the multiple drug-effect analysis with CalcuSyn software, in which the combination index (CI) indicates synergism (CI<0.9), additivity (CI=0.9-1.1) or antagonism (CI>1.1). Drug target analysis was used for WiDr, H630 and SW1116 to investigate whether there was an increase in Pt-DNA adduct formation, DNA damage induction, cell cycle delay and apoptosis. Trifluorothymidine combined with OHP resulted in synergism for all cell lines (all CI<0.9). This was irrespective of schedule in which either one of the drugs was kept at a constant concentration (using variable drug ratio) or when the two drugs were added in a 1 : 1 IC(50)-based molar ratio. Synergism could be increased for WiDr using sequential drug treatment schedules. Trifluorothymidine increased Pt-DNA adduct formation significantly in H630 and SW1116 (14.4 and 99.1%, respectively; P<0.05). Platinum-DNA adducts were retained best in SW1116 in the presence of TFT. More DNA-strand breaks were induced in SW1116 and the combination increased DNA damage induction (>20%) compared with OHP alone. Exposure to the drugs induced a clear cell-cycle S-phase arrest, but was dose schedule and cell line dependent. Trifluorothymidine (TFT) and OHP both induced apoptosis, which increased significantly for WiDr and SW1116 after TFT-OHP exposure (18.8 and 20.6% respectively; P<0.05). The basal protein levels of ERCC1 DNA repair enzyme were not related to the DNA damage that was induced in the cell lines. In conclusion, the combination of TFT with the DNA synthesis inhibitor OHP induces synergism in colorectal cancer cells, but is dependent on the dose and treatment schedule used.
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PMID:Mechanism of trifluorothymidine potentiation of oxaliplatin-induced cytotoxicity to colorectal cancer cells. 1724 97


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