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Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Deregulated proliferation is one of the main events in neoplastic transformation, and this has prompted increased attention being given to the understanding of the mechanisms involved in cell cycle regulation and its alterations. The 'retinoblastoma pathway', a key effector controlling G1-S phase transition, includes several oncogenes and tumour suppressor genes which display a wide range of abnormalities with potential usefulness as markers of evolution or treatment response in prostate cancer. Among these, the existence of p53 mutations seems to predict resistance to radiotherapy or systemic treatment, and p16 overexpression or p27 downregulation seems to serve as markers of poor evolution. The well-established existence of a critical hormonal role in prostate carcinogenesis coupled with the relationship of androgenic activity and regulation of several cell cycle modulators forces cell cycle control in the prostate to be envisioned as a highly complex steroid-influenced system, which will undoubtedly have critical implications in the future management of prostate cancer patients.
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PMID:Alterations of cell cycle-regulatory genes in prostate cancer. 1241 86

Epidemiological and preclinical studies demonstrate that consumption of diets high in omega-3 polyunsaturated fatty acids reduces the risk of colon cancer. Inhibition of colon carcinogenesis by omega-3 polyunsaturated fatty acids is mediated through modulation of more than one signaling pathway that alters the expression of genes involved in colon cancer growth. In our earlier studies on global gene expression with cDNA microarrays, we have shown that treatment of CaCo-2 colon cancer cells with docosahexaenoic acid (DHA) down-regulated the prostaglandin family of genes, as well as cyclooxygenase 2 expression and several cell cycle-related genes, whereas it up-regulated caspases 5, 8, 9, and 10 that are associated with apoptosis. It is known that nitric oxide activates the cyclooxygenase 2 enzyme, which plays a pivotal role in the progression of colon cancer via prostaglandin synthesis and angiogenesis. The present study was undertaken to examine the multifaceted role of DHA in the expression of inducible nitric oxide synthase (iNOS) and of related proinflammatory genes, as those have been shown to play a role in tumor progression. In addition, we aimed to identify associated target genes by DNA microarray, reverse transcription-PCR analysis, and cellular localization of iNOS expression in CaCo-2 cells. Results of this study demonstrate that treatment with DHA down-regulates iNOS in parallel with a differential expression and down-regulation of IFNs, cyclic GMP, and nuclear factor kappa B isoforms. More importantly, our findings clearly demonstrate the up-regulation of cyclin-dependent kinase inhibitors p21((Waf1/Cip1)) and p27, differentiation-associated genes such as alkaline phosphatases, and neuronal differentiation factors. These finding strongly suggest that the antitumor activity of DHA may be attributed, at least in part, to an effect on iNOS regulatory genes. In addition, our results indicate the presence of specific gene expression profiles in human colon cancer that can be used as molecular targets for chemopreventive agents.
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PMID:Modulation of inducible nitric oxide synthase and related proinflammatory genes by the omega-3 fatty acid docosahexaenoic acid in human colon cancer cells. 1261 11

Energy restriction (ER) results in a profound inhibition of chemically induced mammary carcinogenesis. The cancer inhibitory activity of ER has been shown to be associated with lower rates of cell proliferation during both premalignant and malignant stages of this disease process. Moreover, inhibition of carcinogenesis and suppression of cell proliferation occur in animals in which plasma concentrations of insulin-like growth factor (IGF)-I are reduced, and plasma corticosterone levels are increased concomitantly. Given the role of both hormones in signal transduction pathways that can modulate cell cycle progression, albeit via different regulatory mechanisms, we report experiments conducted to determine whether hypothesized effects of changes in plasma levels of IGF-I and corticosterone on cell cycle regulation could be detected in mammary carcinomas occurring in 40% ER rats in comparison to ad libitum fed control rats or 40% ER rats that were energy repleted for 7 days (ER-REP). As determined by appropriate combinations of immunoprecipitations, Western blots, and kinase activity assays, it was found that levels of phosphorylated retinoblastoma and E2F-1 were significantly reduced by ER (approximately 40 and 75%, respectively; P < 0.01), an effect that was partially reversed by ER-REP. Reductions in cyclin-dependent kinase (CDK)2 (82%) and CDK4 (77%) kinase activity in ER carcinomas were likely to account for the observed effects on retinoblastoma and E2F-1. Both Cip1/p21 and Kip1/p27 and levels of these proteins complexed with CDK2 were significantly elevated in ER carcinomas (P < 0.01), and levels of cyclin E were reduced. On the other hand, regulation of CDK4 kinase activity by ER was likely attributable to effects on cyclin D1 as well as increased binding of P16 and P19 to CDK4. The majority of changes induced by ER were reversed by ER-REP. These observations are consistent with the hypothesis that ER exerts its profound cancer inhibitory activity, in part, by multifaceted regulation of cell cycle machinery, possibly via concomitant changes in corticosterone and IGF-1 metabolism, although the role of other hormones and growth factors should not be dismissed.
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PMID:Effect of energy restriction on cell cycle machinery in 1-methyl-1-nitrosourea-induced mammary carcinomas in rats. 1264 81

The effects of lovastatin, a potent inhibitor of HMG CoA reductase, on experimental mammary and prostate oncogenesis, were studied in vitro and in vivo. Lovastatin inhibited cell growth in vitro in a dose-dependent manner for both mammary and prostate cancer cell lines, which was associated with p53-independent apoptosis. Flow cytometric analyses of lovastatin-treated mammary and prostate cancer cells demonstrated cell-cycle G(1) arrest, as well as decreases in S and G(2)/M fractions. p21(Waf1) and p27(Kip1) were induced by lovastatin in both types of cancer cells. Gene expression profiling of cells treated with lovastatin, however, was remarkable for a paucity of transcriptional changes induced by lovastatin. Treatment with lovastatin for 4 weeks did inhibit the formation of pre-neoplastic mammary intraepithelial neoplasias (MIN) in vivo, but not invasive carcinomas in the C3(1)/SV40 TAg transgenic model of mammary cancer. The decreased multiplicity of MIN lesions was associated with increased levels of apoptosis in these lesions. However, cell proliferation in the mammary lesions was not significantly different between lovastatin-treated and control mice 1 day after lovastatin treatment. In female mice treated with lovastatin for 12 weeks, there was a tendency for reduced tumor volume, which did not reach statistical significance. However, lovastatin did not suppress any lesion formation in the prostate of C3(1)/SV40 TAg transgenic male mice. Our results suggest that as lovastatin exerts an inhibitory effect on the development of early mammary lesions of mammary carcinogenesis, this compound may be useful for the chemoprevention of mammary cancer and might have utility as an adjuvant in breast cancer therapy. The chemopreventive effects of lovastatin in vivo, however, may be tissue-specific.
Carcinogenesis 2003 Mar
PMID:Comparative effects of lovastatin on mammary and prostate oncogenesis in transgenic mouse models. 1266 4

Cancer chemopreventive effects of inositol hexaphosphate (IP6), a dietary constituent, have been demonstrated against a variety of experimental tumors, however, limited studies have been done against prostate cancer (PCA), and molecular mechanisms are not well defined. In the present study, we investigated the growth inhibitory effect and associated mechanisms of IP6 in advanced human PCA cells. Advanced human prostate carcinoma DU145 cells were used to study the anticancer effect of IP6. Flow cytometric analysis was performed for cell cycle progression and apoptosis studies. Western immunoblotting, immunoprecipitation and kinase assay were performed to investigate the involvement of G1 cell cycle regulators and their interplay, and end point markers of apoptosis. A significant dose- as well as time-dependent growth inhibition was observed in IP6-treated cells, which was associated with an increase in G1 arrest. IP6 strongly increased the expression of CDKIs (cyclin-dependent kinase inhibitors), Cip1/p21 and Kip1/p27, without any noticeable changes in G1 CDKs and cyclins, except a slight increase in cyclin D2. IP6 inhibited kinase activities associated with CDK2, 4 and 6, and cyclin E and D1. Further studies showed the increased binding of Kip1/p27 and Cip1/p21 with cyclin D1 and E. In down-stream of CDKI-CDK/cyclin cascade, IP6 increased hypophosphorylated levels of Rb-related proteins, pRb/p107 and pRb2/p130, and moderately decreased E2F4 but increased its binding to both pRb/p107 and pRb2/p130. At higher doses and longer treatment times, IP6 caused a marked increase in apoptosis, which was accompanied by increased levels of cleaved PARP and active caspase 3. IP6 modulates CDKI-CDK-cyclin complex, and decreases CDK-cyclin kinase activity, possibly leading to hypophosphorylation of Rb-related proteins and an increased sequestration of E2F4. Higher doses of IP6 could induce apoptosis and that might involve caspases activation. These molecular alterations provide an insight into IP6-caused growth inhibition, G1 arrest and apoptotic death of human prostate carcinoma DU145 cells.
Carcinogenesis 2003 Mar
PMID:Inositol hexaphosphate inhibits growth, and induces G1 arrest and apoptotic death of prostate carcinoma DU145 cells: modulation of CDKI-CDK-cyclin and pRb-related protein-E2F complexes. 1266 18

Within the human prostate epithelium four cell populations can be discriminated based on their expression of keratins (K). Basal cells express high levels of K5 and K14, as well as p63, whereas they have very low levels of androgen receptor, prostate-specific antigen (PSA), K8, and K18. Luminal secretory cells lack p63, K5, and K14 but express high levels of K8, K18, androgen receptor, and PSA. Additionally, cells have been identified with a keratin phenotype intermediate between basal and luminal cells that co-express high levels of K5 and K18 (K5/18) as well as hepatocyte growth factor receptor c-MET. Although intermediate cells have been proposed as precursor cells of prostate cancer, their biology is ill defined. Epithelial cells in proliferative inflammatory atrophy (PIA) appear to be cycling rapidly as indicated by expression of Ki-67, and morphological transitions have been identified between PIA and high-grade prostate intraepithelial neoplasia. Many of the atrophic epithelial luminal cells in PIA are candidates for intermediate cells based in part on weak expression of PSA and androgen receptor, high levels of K8/18, and lack of p63. The objective of this study was to further clarify the phenotype of the proposed intermediate cells in PIA and to quantitatively determine the level in which these intermediate cells preferentially occur in PIA lesions. Intermediate cells were immunohistochemically demonstrated using antibodies to K5, K14, K18, and c-MET. Using radical prostatectomy specimens (n = 15) the area fraction of intermediate cells in normally differentiated prostate epithelium and PIA were quantified by a grid point counting method. Atrophic luminal cells of PIA lesions expressed K5 in 39.2 +/- 7.4% of cells compared to 2.4 +/- 2.3% in normal epithelium (P < 0.00001). By contrast, K14 was only expressed in 3.0 +/- 3.2% of the luminal cells. Previous studies have shown that virtually 100% of these atrophic luminal cells are strongly positive for K8/18. c-MET was present in 44.1 +/- 14.1% of luminal cells in PIA but only in 2.1 +/- 2.8% of luminal cells in normal epithelium (P < 0.00001). To unambiguously determine whether intermediate luminal cells in PIA show increased proliferative activity and decreased p27(kip1) expression, double-staining immunofluorescence of Ki-67 and K5, as well as p27(Kip1) and K5 was performed. Luminal cells in PIA often co-expressed K5 and Ki-67. Although p27(Kip1) was strongly expressed in K5-negative differentiated cells in normal epithelium, p27(Kip1) staining was absent in many of the K5-positive cells in the luminal compartment of PIA. We conclude that cells phenotypically intermediate between basal and secretory cells are enriched in PIA lesions. The finding of a large number of highly proliferating intermediate cells in PIA provides further support that these cells may serve as preferred target cells in prostate carcinogenesis.
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PMID:Intermediate cells in human prostate epithelium are enriched in proliferative inflammatory atrophy. 1270 36

Ovarian cancer is a common gynecological malignancy and a leading cause of death in women. Inactivation of the tumor suppressor gene and deregulation of cyclin E are frequent in human ovarian cancer. The objective of this study was to investigate the expressions and roles of cyclin E, p21 and p27 in 7, 12-dimethylbenzanthracene (DMBA)-induced ovarian tumors in rats. The expressions of cyclin E, p21 and p27 were evaluated by immunohistochemistry and western blot analysis. The expressions of cyclin E and p21 in ovarian tumors was higher than that in normal ovarian surface epithelium. In contrast, the expression of p27 in ovarian tumors was lower than that in normal ovarian surface epithelium. But there were no differences among the cancer types. Positive correlation was present between cyclin E and p21. p27 was negatively correlated with cyclin E and p21. These results suggest that the increased expression of cyclin E and p21, and the decreased expression of p27, occur in DMBA-induced rat ovarian carcinogenesis and result in tumor progression.
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PMID:Overexpression of p21, cyclin E and decreased expression of p27 in DMBA (7, 12-dimethylbenzanthracene)-induced rat ovarian carcinogenesis. 1271 63

The oncogenic HPVs immortalize primary genital keratinocytes in vitro and there is evidence that such lines represent suitable models to examine HPV-induced carcinogenesis. Early in vivo studies and more recent CGH analyses have revealed amplification of chromosome 5p in advanced stage carcinoma of the uterine cervix (CaCx). In the present study, a panel of established CaCx-derived cell lines were analysed by M-FISH to identify recurrent karyotypic abnormalities. Amplification of 5p was observed in 11 of 13 CaCx cell lines harbouring HR (high-risk) HPV. The region of 5p undergoing amplification was confirmed using human band-specific paints. The F-box protein Skp2 is present at 5p13 and its protein is present at increased levels in many cancers of an advanced stage. The HPV16-harbouring cell line W12 shows progressive morphological abnormality with in vitro passage, culminating in an invasive phenotype. The expression of Skp2 at different stages of this progression was investigated utilizing Western blot and TaqMan quantitative PCR. At medium to late passage, gain of 5p as an isochromosome was observed. Increased expression of Skp2 and a reduction in the expression of its target p27 correlated with increasing passage in this line.
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PMID:Amplification of chromosome 5p correlates with increased expression of Skp2 in HPV-immortalized keratinocytes. 1271 29

The pathologic grade and clinical stage have some restrictions for the evaluation of the prognosis of prostate carcinoma. Recently, the function of genes related to apoptosis and tumor suppressor genes on the development, progression,and prognostic value of prostate carcinoma was paid close attention due to further research on the molecular pathology of prostate cancer. Overexpression of Bcl-2 was found in high malignant patients of prostate carcinoma and related to androgen refraction and resistance against anticancer agents as well. The mutation of p53 was found in prostatic intraepithelial neoplasia(PIN) and prostate cancer. p53 can be used as an independent prognostic factor for prostate cancer. The deletion of PTEN and p27 is an important negative factor of prognosis. Overexpression of p21 and p16 which are inhibition protein of cell cycle have effects on the formation and differentiation of prostate cancer. Fas/FasL system plays an important role in apoptosis of prostatic epithelial cells and takes part in the carcinogenesis of prostate. BRCA1 and p73 also have effects on the genesis and development of prostate cancer.
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PMID:[Recent advances on molecular pathology of prostate carcinoma]. 1275 24

Increased secretion of adrenal cortical steroids may account in part for its cancer inhibitory activity of energy restriction (ER). To test this hypothesis, a study was conducted to determine the effects of dietary administration of corticosterone on the post-initiation stage of mammary carcinogenesis. Eighty-four female Sprague-Dawley rats were injected with 50 mg 1-methyl-1-nitrosourea/kg body wt (i.p.) at 21 days of age. One week later, animals were randomly divided into three groups and fed control diet, or that diet to which was added 200 or 400 mg corticosterone/kg. Diets were fed for 5 weeks after which the experiment was terminated. With increasing dietary corticosterone, a dose-dependent reduction in the incidence (P=0.03), multiplicity (P=0.003) and size (P<0.003) of mammary carcinomas was observed. Dietary administration of corticosterone also reduced plasma insulin-like growth factor-1 (IGF-1) and levels of IGF-1 receptor in mammary carcinomas (P<0.01). In order to investigate molecular mechanisms underlying anticancer activity, the levels and activities of cell cycle components involved in the G1-S transition were investigated in mammary carcinomas that emerged in treated animals. Levels of cyclin D1, cyclin E, cyclin-dependent kinase (CDK)-2 and CDK-4 were reduced in carcinomas from corticosterone treated rats; whereas, levels of cyclin-dependent kinase inhibitors (CKI) Kip1/p27 and Cip1/p21 were elevated. Binding of these CKIs to both the cyclin D1-CDK-4 complex and the cyclin E-CDK-2 complex were increased and the kinase activities of these complexes were reduced with increasing dietary corticosterone. These effects were consistent with those observed in response to ER in vivo and corticosterone exposure in vitro. Whereas the effects of exogenously administered corticosterone and ER had many similarities, the lower efficacy of corticosterone versus ER in inhibiting the carcinogenic process imply that changes in cortical steroid metabolism alone are unlikely to explain the cancer inhibitory activity of ER.
Carcinogenesis 2003 Jul
PMID:Mechanisms by which energy restriction inhibits rat mammary carcinogenesis: in vivo effects of corticosterone on cell cycle machinery in mammary carcinomas. 1280 24


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