Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Axin2 is a negative regulator of Wnt/beta-catenin signalling with a role in tumour suppression. Its expression can be up-regulated by E2F1 allowing cross-talk between the pRb/E2F and Wnt/beta-catenin pathways, which both have critical roles in the development of many cancers. Thereby, axin2 may have a crucial role in carcinogenesis and here we examine the regulation of its expression. Axin2 mRNAs contain one of three different 5' untranslated regions that can have profound effects on the efficiency of axin2 translation. We show that axin2 mRNA expression is altered in tumours at levels of both total mRNA and relative proportions of alternative 5' untranslated regions. Moreover, the translational efficiencies defined by these 5' untranslated regions are modulated considerably. Additionally, we show that stability of axin2 protein provides a further level of expression regulation. We discuss this complex regulation in terms of axin2's function in carcinogenesis.
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PMID:Regulation of axin2 expression at the levels of transcription, translation and protein stability in lung and colon cancer. 1588 87

E2F1 is a transcription factor that plays a well-documented role during S phase progression and apoptosis. We had previously postulated that the low level of E2F1 in primary lung adenocarcinoma contributes to their carcinogenesis. Here, we show that E2F1 triggers apoptosis in various lung adenocarcinoma cell lines by a mechanism involving the specific downregulation of the cellular FLICE-inhibitory protein short, leading to caspase-8 activation at the death-inducing signaling complex. Importantly, we also provide evidence that E2F1 sensitizes tumor as well as primary cells to apoptosis mediated by FAS ligand or tumor necrosis factor-related apoptosis-inducing ligand, and enhances the cytotoxic effect of T lymphocytes against tumor cells. Finally, we describe the specific overexpression of c-FLIP(S) in human lung adenocarcinomas with low level of E2F1. Overall, our data identify E2F1 as a critical determinant of the cellular response to death-receptor-mediated apoptosis, and suggest that its downregulation contributes to the immune escape of lung adenocarcinoma tumor cells.
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PMID:E2F1 induces apoptosis and sensitizes human lung adenocarcinoma cells to death-receptor-mediated apoptosis through specific downregulation of c-FLIP(short). 1605 33

The E2F1 transcription factor, which is deregulated in most human cancers by mutations in the p16-cyclin D-Rb pathway, has both oncogenic and tumor-suppressive properties. This is dramatically illustrated by the phenotype of an E2F1 transgenic mouse model that spontaneously develops tumors in the skin and other epithelial tissues but is resistant to papilloma formation when subjected to a two-stage carcinogenesis protocol. Here, this E2F1 transgenic model was used to further explore the tumor-suppressive property of E2F1. Transgenic expression of E2F1 was found to inhibit ras-driven skin carcinogenesis at the promotion stage independent of the type of promoting agent used. E2F1 transgenic epidermis displayed increased expression of p19(ARF), p53, and p21(Cip1). Inactivation of either p53 or Arf in E2F1 transgenic mice restored sensitivity to two-stage skin carcinogenesis. While Arf inactivation impaired tumor suppression and p21 induction by E2F1, it did not reduce the level of apoptosis observed in E2F1 transgenic mice. Based on these findings, we propose that E2F1 suppresses ras-driven skin carcinogenesis through a nonapoptotic mechanism involving ARF and p53.
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PMID:E2F1 suppresses skin carcinogenesis via the ARF-p53 pathway. 1620 40

Quercetin, a natural product derived from grapes, has been shown to prevent carcinogenesis in murine models. We report here that quercetin induces anti-proliferation and arrests G2/M phase in U937 cells. The G2/M phase accumulation was accompanied by an increase in the level of the cyclin B. In contrast, the level of the cyclin D, cyclin E, E2F1, and E2F2 was marked decreased in quercetin-treated U937 cells. Removal of quercetin from the culture medium stimulates U937 cells to synchronously re-enter the cell cycle, decrease expression level of cyclin B, and increased the expression level of cyclin D and cyclin E. These data demonstrate that quercetin causes reversible G2/M phase arrest, which was related with dramatic changes in the level of cyclin B, cyclin D, and cyclin E. Quercetin-induced down-regulation of cyclin D and cyclin E was associated with suppression of transcriptional levels but not protein stability. In addition, quercetin-treated U937 cells showed DNA fragmentation, increased sub-G1 population, and generated a 60kDa cleavage product of PLC-gamma1 in a dose-dependent manner, which were significantly inhibited by z-VAD-fmk. These data clearly indicate that quercetin-induced apoptosis is associated with caspase activation. In summary, the growth inhibition of the quercetin is highly related to cell cycle arrest at the G2/M phase and induction of caspase-dependent apoptosis in human promonocytic U937 cells.
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PMID:Quercetin arrests G2/M phase and induces caspase-dependent cell death in U937 cells. 1627 26

Mutation or inactivation of the retinoblastoma (Rb) tumor suppressor occurs in most human tumors and results in the deregulation of several members of the E2F family of transcription factors. Among the E2F family, E2F3 has been implicated as a key regulator of cell proliferation and E2F3 gene amplification and overexpression is detected in some human tumors. To study the role of E2F3 in tumor development, we established a transgenic mouse model expressing E2F3a in a number of epithelial tissues via a keratin 5 (K5) promoter. Transgenic expression of E2F3a leads to hyperproliferation, hyperplasia and increased levels of p53-independent apoptosis in transgenic epidermis. Consistent with data from human cancers, the E2F3a transgene is found to have a weak oncogenic activity on its own and to significantly enhance the response to a skin carcinogenesis protocol. The phenotype of K5 E2F3a transgenic mice is distinct from similar transgenic mice expressing E2F1 or E2F4. In particular, E2F3a has a unique apoptotic activity and lacks the tumor suppressive property of E2F1 in this model system.
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PMID:E2F3a stimulates proliferation, p53-independent apoptosis and carcinogenesis in a transgenic mouse model. 1634 Mar 9

The MDM2 oncogene has an important role in human carcinogenesis and has been suggested as a novel target for cancer therapy. Many published in vitro and in vivo investigations have demonstrated that various MDM2 inhibitors including antisense oligonucleotides, siRNA, and small molecule MDM2 inhibitors have antitumor activity in in vitro and in vivo human cancer models, used alone or in combination with cancer chemotherapeutics and radiation therapy. For example, the mixed backbone antisense oligonucleotide developed in our laboratory specifically inhibited MDM2 expression in a dose- and time-dependent manner, resulting in significant antitumor activity in vitro and in vivo. Interestingly, the antisense MDM2 inhibitors have a broad spectrum of antitumor activities in human cancers, regardless of p53 status. These results prompted new investigations into the p53-independent functions of MDM2. This article summarizes the biochemical and molecular studies of the role of MDM2 in the regulation of p21 and E2F1 expression, stability and function, providing evidence for the utility of RNA-silencing technologies, including antisense oligonucleotides and siRNAs.
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PMID:Novel MDM2 p53-independent functions identified through RNA silencing technologies. 1639 38

Centrosome abnormalities are observed in human cancers and have been associated with aneuploidy, a driving force in tumour progression. However, the exact pathways that tend to cause centrosome abnormalities have not been fully elucidated in human tumours. Using a series of 68 non-small-cell lung carcinomas and an array of in vitro experiments, the relationship between centrosome abnormalities, aneuploidy, and the status of key G1 to S-phase transition cell-cycle molecules, involved in the regulation of centrosome duplication, was investigated. Centrosome amplification and structural abnormalities were common (53%), were strongly related to aneuploidy, and, surprisingly, were even seen in adjacent hyperplastic regions, suggesting the possibility that these are early lesions in lung carcinogenesis. Cyclin E and E2F1 overexpression, but not p53 mutation, was observed to correlate with centrosome abnormalities in vivo (p = 0.029 and p = 0.015, respectively). This was further strengthened by the observation that cyclin E was specifically present in the nucleus and/or cytoplasm of the cells that contained centrosome aberrations. The cytoplasmic cyclin E signal may be attributed, in part, to the presence of truncated low-molecular-weight isoforms of cyclin E. In order to isolate the effect of cyclin E on the appearance of centrosome abnormalities, a U2OS tetracycline-repressible cyclin E cell line that has a normal centrosome profile by default was used. With this system, it was confirmed in vitro that persistent cyclin E overexpression is sufficient to cause the appearance of centrosome abnormalities.
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PMID:Centrosome abnormalities are frequently observed in non-small-cell lung cancer and are associated with aneuploidy and cyclin E overexpression. 1673 12

We recently reported that the expression of dbpA (DNA binding protein A) is associated with advanced stages of human hepatocellular carcinoma (HCC) and that its transcription is positively regulated by E2F1, which is also implicated in hepatocarcinogenesis. To study the in vivo effect of dbpA on hepatocarcinogenesis, we generated the dbpA-transgenic mouse that specifically expressed a transgene in hepatocytes. Here, we studied the effect of dbpA on the expression of other cellular genes by using microarray analyses. The expression profiles from livers of 31- and 32-week-old male transgenic mice [Tg(+)] that did not show any morphological changes and from livers of their male wild-type littermates [Tg(-)] were compared. Expression differences detected by microarray analyses were validated by reverse transcription-polymerase chain reaction (RT-PCR) using total RNA samples from livers of 3 pairs of Tg(+) and (-) mice. The 11 up-regulated genes included 7 carcinogenesis-related genes (Igfbp1, Tff3, Hpx, Orm2, Ctsl, Plg, Jdp1), and the 9 down-regulated genes included Car3 that is associated with the protection of cells from attack by oxygen radicals. We confirmed that the expression of Igfbp1 (insulin like growth factor binding protein 1) was reduced by siRNA targeting dbpA in the human HCC cell line. In conclusion, our present data suggested that dbpA could be positively involved in carcinogenesis by changing the expression profiles of cellular genes.
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PMID:Gene expression profile of DNA binding protein A transgenic mice. 1686 84

D,L-Sulforaphane (SFN), a synthetic analogue of cruciferous vegetable-derived isomer l-SFN, suppresses proliferation of cancer cells by causing apoptosis but the mechanism of cell death is not fully understood. We used LNCaP (wild-type p53) and PC-3 (p53 deficient) human prostate cancer cells to gain further insights into the mechanism of SFN-induced apoptosis. The LNCaP cell line was relatively more sensitive to SFN-induced apoptosis compared with PC-3. The SFN treatment caused stabilization of p53 protein in LNCaP cells, but SFN-mediated apoptosis was not attenuated by knockdown of p53 protein. Instead, the differential sensitivity of these cells to SFN-induced apoptosis correlated with difference in kinetics of Bax conformational change. Ectopic expression of Bcl-2 failed to confer protection against SFN-induced cell death in LNCaP cells. Treatment of PC-3 cells with SFN resulted in a marked decrease in the levels of inhibitor of apoptosis (IAP) family proteins (cIAP1, cIAP2 and XIAP), which was accompanied by inhibition of nuclear translocation of p65-nuclear factor kappaB (NFkappaB). The effect of SFN on levels of IAP family proteins as well as transcriptional activity of NFkappaB was biphasic in LNCaP cells. The SFN-treated LNCaP and PC-3 cells exhibited a marked increase in protein level of Apaf-1, which was accompanied by an increase in transcriptional activity of E2F1. The SFN-induced apoptosis in both cell lines was significantly attenuated by Apaf-1 protein knockdown. In conclusion, the present study reveals a complex signaling mechanism involving Bax activation, downregulation of IAP family proteins and Apaf-1 induction in regulation of SFN-induced cell death.
Carcinogenesis 2007 Jan
PMID:D,L-Sulforaphane-induced cell death in human prostate cancer cells is regulated by inhibitor of apoptosis family proteins and Apaf-1. 1692 Jul 35

CDKN2A locus on chromosome 9p21 encodes two tumour suppressor proteins pl6INK4A, which is a regulator of the retinoblastoma (RB) protein, and p14ARF, which is involved in the ARF-Mdm2-p53 pathway. The aim of this study was to determine if CDKN2A gene products are implicated in differentiated thyroid carcinogenesis and progression. We used real-time quantitative RT-PCR and immunohistochemistry to assess both transcripts and proteins levels in 60 tumours specimens. Overexpression of p14ARF and pl6INK4A was observed in follicular adenomas, follicular carcinomas and papillary carcinomas, while downregulation was found in oncocytic adenomas compared to nontumoral paired thyroid tissues. These deregulations were statistically significant for pl6INK4a (P=0.006) in follicular adenomas and close to statistical significance for p14ARF in follicular adenomas (P=0.06) and in papillary carcinomas (P=0.05). In all histological types, except papillary carcinomas, we observed a statistically significant relationship between p14ARF and E2F1 (r=0.64 to 1, P<0.05). Our data are consistent with involvement of CDKN2A transcript upregulation in thyroid follicular tumorigenesis as an early event. However, these deregulations do not appear to be correlated to the clinical outcome and they could not be used as potential prognostic markers.
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PMID:The status of CDKN2A alpha (p16INK4A) and beta (p14ARF) transcripts in thyroid tumour progression. 1711 77


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