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)

More than 80 years ago Otto Warburg suggested that cancer might be caused by a decrease in mitochondrial energy metabolism paralleled by an increase in glycolytic flux. In later years, it was shown that cancer cells exhibit multiple alterations in mitochondrial content, structure, function, and activity. We have stably overexpressed the Friedreich ataxia-associated protein frataxin in several colon cancer cell lines. These cells have increased oxidative metabolism, as shown by concurrent increases in aconitase activity, mitochondrial membrane potential, cellular respiration, and ATP content. Consistent with Warburg's hypothesis, we found that frataxin-overexpressing cells also have decreased growth rates and increased population doubling times, show inhibited colony formation capacity in soft agar assays, and exhibit a reduced capacity for tumor formation when injected into nude mice. Furthermore, overexpression of frataxin leads to an increased phosphorylation of the tumor suppressor p38 mitogen-activated protein kinase, as well as decreased phosphorylation of extracellular signal-regulated kinase. Taken together, these results support the view that an increase in oxidative metabolism induced by mitochondrial frataxin may inhibit cancer growth in mammals.
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PMID:Induction of oxidative metabolism by mitochondrial frataxin inhibits cancer growth: Otto Warburg revisited. 1626 3

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

Mitochondrial Lon protease (Lon) regulates several mitochondrial functions, and is inhibited by the anticancer molecule triterpenoid 2-cyano-3, 12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO), or by its C-28 methyl ester derivative (CDDO-Me). To analyze the mechanism of action of triterpenoids, we investigated intramitochondrial reactive oxygen species (ROS), mitochondrial membrane potential, mitochondrial mass, mitochondrial dynamics and morphology, and Lon proteolytic activity in RKO human colon cancer cells, in HepG2 hepatocarcinoma cells and in MCF7 breast carcinoma cells. We found that CDDO and CDDO-Me are potent stressors for mitochondria in cancer cells, rather than normal non-transformed cells. In particular, they: i) cause depolarization; ii) increase mitochondrial ROS, iii) alter mitochondrial morphology and proteins involved in mitochondrial dynamics; iv) affect the levels of Lon and those of aconitase and human transcription factor A, which are targets of Lon activity; v) increase level of protein carbonyls in mitochondria; vi) lead to intrinsic apoptosis. The overexpression of Lon can rescue cells from cell death, providing an additional evidence on the role of Lon in conditions of excessive stress load.
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PMID:Inhibition of Lon protease by triterpenoids alters mitochondria and is associated to cell death in human cancer cells. 2631 56