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

In contrast to most other systems, TPA induced TGc activity and protein in SW620 human colon carcinoma cells. This induction was accompanied by cell growth inhibition and increased apoptosis. The general protein kinase-C inhibitor GF-109203X blocked the induction of TGc by TPA, whereas the specific inhibitor of the PKC alpha isoform, the indocarbazole Go6976, reduced it by 40%. These PKC inhibitors had similar inhibitory effects on TPA increased apoptosis and inhibition of cell growth, suggesting that the observed actions of TPA are mediated by PKC, and a close connection between TGc activity, increased apoptosis and cell growth inhibition. We conclude that TPA may offer new approaches in the management of colon cancer cell growth.
 ...
PMID:TPA induces transglutaminase C and inhibits cell growth in the colon carcinoma cell line SW620. 912 46

KRN 5500 is a new semi-synthetic antitumor compound derived from spicamycin and has a unique structure. The compound showed a broad spectrum of antitumor activity against human colon, stomach, esophageal, breast and lung cancer xenografts in nude mice. Therapeutic efficacy of KRN 5500 against liver metastasis of COL-1 human colon cancer scid mice was examined. The treatment with KRN 5500 inhibited tumor growth in the liver and reduced the serum TPA concentration to a normal level. KRN 5500 inhibits protein synthesis in rabbit reticulocyte lysates. Among several metabolites of KRN 5500, only SAN-Gly showed a potent inhibitory activity against protein synthesis in reticulocyte lysates. TLC analysis of KRN 5500 metabolites using 7 human colon cancer cell lines and 3 normal cell lines demonstrated a correlation between the cytotoxicity of KRN 5500 and converting activity from KRN 5500 to SAN-Gly. These results indicate that SAN-Gly is the intracellular active metabolite and that converting activity from KRN 5500 to SAN-Gly is the major determinant of KRN 5500 cytotoxicity.
 ...
PMID:[Protein synthesis inhibitor--antitumor activity and mode of action of KRN 5500]. 930 56

To identify the genes located downstream of the activated Ki-Ras signaling pathways in human colon cancer cells, a PCR-based cDNA subtraction library was constructed between HCT116 cells and HCT116-derived activated Ki-ras-disrupted cells (HKe3). One of the genes in HCT116 that was evidently up-regulated was epiregulin, a member of the epidermal growth factor family that is expressed in many kinds of human cancer cells. HKe3-stable transfectants expressing activated Ki-Ras regained over-expression of epiregulin. To further elucidate the biochemical structure and significance of epiregulin expression in tumorigenesis, HKe3-stable transfectants expressing epiregulin (e3-pSE cells) were established. Epiregulin existed as highly glycosylated membrane-bound forms, and TPA rapidly induced ectodomain shedding of epiregulin. Furthermore, the conditioned medium of e3-pSE cells showed more DNA synthesis for 32D cells expressing epidermal growth factor receptor (DER) cells than that of HKe3. Although anchorage-independent growth in soft agar was not observed for e3-pSE cells, tumorigenicity in nude mice was observed evidently, and their growth rate was correlated with each amount of exogenous epiregulin expression. These results suggested that activated Ki-Ras will be one of the factors contributing to the overexpression of epiregulin in human colon cancer cells, and that epiregulin will play a critical role in human tumorigenesis in vivo.
 ...
PMID:Involvement of deregulated epiregulin expression in tumorigenesis in vivo through activated Ki-Ras signaling pathway in human colon cancer cells. 1115 86

Derivatives based on a benzotropolone skeleton (9-26) have been prepared by the enzymatic coupling (horseradish peroxidase/H2O2) of selected pairs of compounds (1-8), one with a vic-trihydroxyphenyl moiety, and the other with an ortho-dihydroxyphenyl structure. Some of these compounds have been found to inhibit TPA-induced mice ear edema, nitric oxide (NO) synthesis, and arachidonic acid release by LPS-stimulated RAW 264.7 cells. Their cytotoxic activities against KYSE 150 and 510 human esophageal squamous cell carcinoma and HT 29 human colon cancer cells were also evaluated.
 ...
PMID:Enzymatic synthesis of tea theaflavin derivatives and their anti-inflammatory and cytotoxic activities. 1472 64

We recently showed that zerumbone, a sesquiterpene found in subtropical ginger, suppresses colonic tumor marker formation in rats and induces apoptosis in colon cancer cell lines. In our present study, the anti-tumor initiating and promoting activities of zerumbone in mouse skin were evaluated using a conventional 2-stage carcinogenesis model. A single topical pretreatment to mouse skin (2 micromol) 24 hr before application of dimethylbenz[a]anthracene (0.2 micromol) markedly suppressed tumor incidence by 60% and the number of tumors by 80% per mouse. Repeated pretreatment (16 nmol) twice weekly during the post-initiation phase reduced the number of 12-O-tetradecanoylphorbol-13-acetate (TPA, 1.6 nmol)-induced tumors by 83% as well as their diameter by 57%. Multiple reverse transcriptase (RT) PCR experiments revealed that zerumbone (2 micromol) enhanced the mRNA expression level of manganese superoxide dismutase, glutathione peroxidase-1, glutathione S-transferase-P1 and NAD(P)H quinone oxidoreductase in the epidermis, but not that of cytochrome p450 1A1 or 1B1. Further, it diminished TPA-induced cyclooxygenase-2 protein expression and phosphorylation of extracellular signal-regulated kinase 1/2, while pretreatment(s), in either the priming or activation stage or both, reduced double TPA application-induced hydrogen peroxide formation and edema induction by 29% to 86%, respectively. Histologic examination revealed that pretreatment(s) with zerumbone suppressed leukocyte infiltration and reduced proliferating cell nuclear antigen-labeling indices. Together, our results indicate that zerumbone is a promising agent for the prevention of both tumor initiating and promoting processes, through induction of anti-oxidative and phase II drug metabolizing enzymes as well as attenuation of proinflammatory signaling pathways.
 ...
PMID:Zerumbone, a sesquiterpene in subtropical ginger, suppresses skin tumor initiation and promotion stages in ICR mice. 1512 79

Although their sensitivity is not high, SCC, TPA and IAP are useful for esophageal cancer. The sensitivity of CEA, CA 19-9, is relatively high, especially in well-differentiated adenocarcinoma of gastric cancer with lymph node metastasis. AFP is specific to liver metastasis from gastric cancer, and CA 125 is also specific to peritoneal dissemination. CA 72-4 and NCC-ST-439 are useful markers for advanced staging. CEA, CA 19-9, is useful for colon cancer, especially for predicting preoperative staging. Half-life and doubling time of tumor markers is useful in some cases for the evaluation of operation and chemotherapy. We showed our data concerning postoperative CEA and/or CA 19-9 monitoring after operation for gastric cancer in 120 recurrent patients. Positivities of CEA and CA 19-9 for recurrence were 65.8% and 85.0%, respectively, both of which were significantly higher than the preoperative sensitivities (28.3% and 45.0%, respectively). In most patients with high levels of preoperative CEA and/or CA 19-9, these tumor markers increased again at recurrence. Recurrent diseases were detected between 5 months after detection by diagnostic imagings and 12 months before detection by diagnostic imagings (mean of 3.1+/-3.6 months before detection by diagnostic imagings) and between 10 months after detection by diagnostic imagings and 13 months before detection by diagnostic imagings (mean 2.2+/-3.9 months before detection by diagnostic imagings) by CEA and CA 19-9 monitorings, respectively. These results suggest that CEA and/or CA 19-9 monitoring after operation was useful to predict the recurrence of gastric cancer, especially in almost all the patients with high preoperative levels of these markers.
 ...
PMID:[Gastrointestinal cancer]. 1533 58

Activation of protein kinase C delta (PKCdelta) is believed to be pro-apoptotic. PKCdelta is reported to be reduced in colon cancers. Using a colon cancer cell line, COLO 205, we have examined the roles of PKCdelta in apoptosis and of caspase-3 in the activation and inhibition of PKCdelta. PKCdelta activation with bistratene A and its inhibition with rottlerin induced apoptosis. Effects of PKC activators and inhibitors were additive, suggesting that PKCdelta down-regulation was responsible for the effects on apoptosis. Different apoptotic pathways induced PKCdelta cleavage, but the fragment produced was inactive in kinase assays. Caspase-3 inhibition did not block DNA fragmentation or PKCdelta proteolysis despite blocking intracellular caspase-3 activity. Calpain inhibition with calpeptin did not prevent TPA-induced PKCdelta cleavage. We conclude that in colonocytes, inhibition of PKCdelta is sufficient to lead to caspase-3-independent apoptosis. Caspase-3 does not cleave PKCdelta to an active form, nor does caspase-3 inhibition block apoptosis.
 ...
PMID:Protein kinase C delta is not activated by caspase-3 and its inhibition is sufficient to induce apoptosis in the colon cancer line, COLO 205. 1549 16

PKC-delta is a serine/threonine kinase that mediates diverse signal transduction pathways. We previously demonstrated that overexpression of PKC-delta slowed the G1 progression of Caco-2 colon cancer cells, accelerated apoptosis, and induced cellular differentiation. In this study, we further characterized the PKC-delta dependent signaling pathways involved in these tumor suppressor actions in Caco-2 cells overexpressing PKC-delta using a Zn2+ inducible expression vector. Consistent with a G1 arrest, increased expression of PKC-delta caused rapid and significant downregulation of cyclin D1 and cyclin E proteins (50% decreases, P<0.05), while mRNA levels remained unchanged. The PKC agonist, phorbol 12-myristate 13-acetate (TPA, 100 nM, 4 h), induced two-fold higher protein and mRNA levels of p21(Waf1), a cyclin-dependent kinase (cdk) inhibitor in PKC-delta transfectants compared with empty vector (EV) transfected cells, whereas the PKC-delta specific inhibitor rottlerin (3 microM) or knockdown of this isoenzyme with specific siRNA oligonucleotides blocked p21(Waf1) expression. Concomitantly, compared to EV control cells, PKC-delta upregulation decreased cyclin D1 and cyclin E proteins co-immunoprecipitating with cdk6 and cdk2, respectively. In addition, overexpression of PKC-delta increased binding of cdk inhibitor p27(Kip1) to cdk4. These alterations in cyclin-cdks and their inhibitors are predicted to decrease G1 cyclin kinase activity. As an independent confirmation of the direct role PKC-delta plays in cell growth and cell cycle regulation, we knocked down PKC-delta using specific siRNA oligonucleotides. PKC-delta specific siRNA oligonucleotides, but not irrelevant control oligonucleotides, inhibited PKC-delta protein by more than 80% in Caco-2 cells. Moreover, PKC-delta knockdown enhanced cell proliferation ( approximately 1.4-2-fold, P<0.05) and concomitantly increased cyclin D1 and cyclin E expression ( approximately 1.7-fold, P<0.05). This was a specific effect, as nontargeted PKC-zeta was not changed by PKC-delta siRNA oligonucleotides. Consistent with accelerated apoptosis in PKC-delta transfectants, compared to EV cells, PKC-delta upregulation increased proapoptotic regulator Bax two-fold at mRNA and protein levels, while antiapoptotic Bcl-2 protein was decreased by 50% at a post-transcriptional level. PKC-delta specific siRNA oligonucleotides inhibited Bax protein expression by more than 50%, indicating that PKC-delta regulates apoptosis through Bax. Taken together, these results elucidate two critical mechanisms regulated by PKC-delta that inhibit cell cycle progression and enhance apoptosis in colon cancer cells. We postulate these antiproliferative pathways mediate an important tumor suppressor function for PKC-delta in colonic carcinogenesis.
 ...
PMID:Protein kinase C delta inhibits Caco-2 cell proliferation by selective changes in cell cycle and cell death regulators. 1643 69

Biphenolic components in Magnolia obovata including magnolol and honokiol have shown several pharmacological activities such as anti-tumor, anti-oxidant and anti-inflammatory effects. Previously in cultured macrophage Raw264.7 cells and fibroblast, we found that obovatol, an active compound isolated from M. obovata inhibited NF-kappaB activity which has been known to be a significant transcriptional factor to control of cancer cell growth. We investigated here whether obovatol could inhibit NF-kappaB activity, and thereby inhibit cancer cell growth in prostate (LNCaP and PC-3) and colon cancer (SW620 and HCT116) cells. Treatment of obovatol (10, 15, 20, 25 microM) inhibits cancer cell growth in the absence or the presence of tumor necrosis factor-alpha (TNF-alpha , 10 ng/ml) and tetradecanoyl phorbol acetate (TPA 10 or 50 nM) in a concentration-dependent manner through induction of apoptotic cell death. Cytotoxic activity was not observed in normal cells with up to 50 muM obovatol. It was also found that obovatol inhibited TNF-alpha and TPA-induced transcriptional and DNA binding activities of NF-kappaB. In further study, obovatol decreased translocation p65 and p50 into nucleus via decrease of phosphorylation of IkappaB. Correlated well with the induction of apoptosis, obovatol increased the expression of the apoptotic genes; Bax, caspase-3, caspase-9, whereas inhibited expression of anti-apoptotic genes; Bcl-2, inhibitor of apoptosis protein (IAP-1) and X chromosome IAP (XIAP) as well as the cell proliferation marker genes; Cox-2, c-Fos, c-Jun and cyclin D1. These results suggest that obovatol inhibits prostate and colon cancer cell growth via induction of apoptotic cell death, and that inhibition of NF-kappaB may be a significant as its action mechanism.
 ...
PMID:Growth inhibitory effects of obovatol through induction of apoptotic cell death in prostate and colon cancer by blocking of NF-kappaB. 1824 58

We previously identified the induction of senescence in melanoma cell lines sensitive to diterpene esters, indicating a therapeutic potential. Here we compared the cytostatic effects of two diterpene esters: the prototypic PKC-activating drug TPA (12-O-tetradecanoylphorbol-13-acetate), and the novel compound PEP008 (20-O-acetyl-ingenol-3-angelate) in cell lines derived from melanoma, breast cancer and colon cancer. The diterpene esters induced permanent growth arrest with characteristics of senescence in a subset of cell lines in all three solid tumor models at 100-1000 ng/ml. Use of the PKC inhibitor bisindolylmaleimide-l demonstrated that activation of PKC was required for growth arrest. Full genome expression profiling identified pivotal genes involved in DNA synthesis and cell cycle control down-regulated by treatment in all three sensitive tumor models. At the protein level, prolonged down-regulation of E2F-1 and proliferating cell nuclear antigen (PCNA), sustained expression of p21(WAF1/CIP1) and dephosphorylation of retinoblastoma (Rb) occurred in the sensitive cells. Additionally, the type II tumor suppressor HRASLS3, which has a role in mitogen-activated protein kinase (MAPK) pathway suppression, was constitutively elevated in cell lines resistant to the senescence effects compared to their sensitive counterparts. Together, these results demonstrate that both TPA and the novel PKC-activating drug PEP008 induce growth arrest with characteristics of senescence in solid tumor cell lines derived from a variety of tissue types, and by a similar mechanism. PKC-activating diterpene esters may therefore have therapeutic potential in a subset of breast cancer, colon cancer and melanoma tumors.
 ...
PMID:The induction of senescence-like growth arrest by protein kinase C-activating diterpene esters in solid tumor cells. 1963 13


<< Previous 1 2 3 Next >>