Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0178874 (tumor progression)
 40,807 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Numerous evidences have demonstrated the relationship between high fat diets and onset and/or progression of several diseases associated with obesity. Moreover, several studies have shown that dietary fat generally increases cancer risk. Fatty acids also play a crucial role in the development of these pathologies. The nuclear receptors PPARgamma and PPARdelta are molecular targets for fatty acids. These receptors exert opposite actions in the tumorigenesis process. Indeed, whereas fatty acids-activated PPARdelta is implicated in cellular proliferation and appears to play some role in tumor onset, the activation of PPARgamma by fatty acids or some of their metabolites, seems to counteract tumor progression. Then, PPARgamma and PPARdelta could constitute new potential pharmaceutical targets for cancer treatment.
 ...
PMID:[PPARdelta and PPARgamma: roles in fatty acids signalling, implication in tumorigenesis]. 1184 22

Peroxisome proliferator-activated receptor gamma (PPAR gamma) immunohistochemical expression was analyzed in 75 human bladder tumor specimens, where the expression of some angiogenic factors, such as vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), platelet-derived endothelial cell growth factor (PDECGF), and tumor progression markers, such as epidermal growth factor receptor (EGFr), p16, mutated p53, and normal pRB, were also analyzed. The results were then compared to the clinical and pathological characteristics of the disease. PPAR gamma was expressed more significantly in papillary tumors than in solid cancers, and its presence was associated with statistical significance to low incidence of tumor recurrence or progression. This significant association was observed also when PPAR gamma was expressed in the presence of PDECGF, which resulted, when considered alone, to an angiogenic factor typical of solid cancers and appeared related to poor prognosis. In the presence of bFGF, on the contrary, PPAR gamma expression no longer resulted to a significant association with low incidence of tumor recurrence or progression, suggesting a possible worsening role of this angiogenic factor, typical of papillary cancers, in its interaction with PPAR gamma.
 ...
PMID:The role of peroxisome proliferator-activated receptor gamma in bladder cancer in relation to angiogenesis and progression. 1188 83

Tumors of thyroid follicular cells provide a very interesting model to understand the development of human cancer. It is becoming apparent that distinct molecular events are associated with specific stages in a multistep tumorigenic process with good genotype/ phenotype correlation. For instance, mutations of the gsp and thyroid-stimulating hormone receptor genes are associated with benign hyperfunctioning thyroid nodules and adenomas while alterations of other specific genes, such as oncogenic tyrosine kinase alterations (RET/PTC, TRK) in papillary carcinoma and the newly discovered PAX8/peroxisome proliferator-activated receptor gamma rearrangement, are distinctive features of cancer. Although activating RAS mutations occur at all stages of thyroid tumorigenesis, evidence is accumulating that they may also play an important role in tumor progression, a role that is well documented for p53. Environmental factors (iodine deficiency, ionizing radiations) have been shown to play a crucial role in promoting the development of thyroid cancer, influencing both its genotypic and phenotypic features. It is possible that the follicular thyroid cell has unique ways to respond to DNA damage. Similarly to leukemia or sarcomas (and unlike most epithelial cancers), numerous specific rearrangements are being discovered in thyroid cancer suggesting preferential activation of DNA repair instead of cell death programs after environmentally induced genetic alterations.
 ...
PMID:Molecular pathobiology of thyroid neoplasms. 1266 46

Invasion and metastasis are the main causes of death in breast cancer patients. Increased expression of matrix metalloproteinases (MMPs), especially gelatinases (MMP-2 and -9), has been closely associated with tumor progression. One of the nuclear hormone receptors (NHR), peroxisome proliferator-activated receptor gamma (PPARgamma), is a ligand-activated transcriptional factor that regulates cell proliferation, differentiation and apoptosis in both normal and cancer cells. Recent data indicate that PPARgamma activation by its ligands can also lead to the inhibition of gelatinase B (MMP-9) and the blockage of migration in macrophages and muscle cells, implying the possibility that PPARgamma ligands may possess anti-invasive activities on tumor cells. In this study, we showed that treatment of the highly aggressive human breast cancer cell line MDA-MB-231 with the synthetic PPARgamma ligands pioglitazone (PGZ), rosiglitazone (RGZ), GW7845 or its natural ligand 15-deoxy-delta 12, 14-prostaglandin J2(15d-PGJ2), at concentrations at which no obvious cytotoxicity was observed in vitro, led to a significant inhibition of the invasive capacities of this cell line through a reconstituted basement membrane (Matrigel) in a Transwell chamber model. All-trans-retinoic acid (ATRA), a ligand for retinoic acid receptor (RAR), was also studied and showed a similar inhibitory effect on invasion. Although no change was observed in the expression of MMP-9 after challenge with PPARgamma ligands and/or ATRA on this cell line, the natural tissue inhibitor of gelatinases, namely the tissue inhibitor of MMP 1 (TIMP-1) was upregulated by these treatments and the gelatinolytic activities of gelatinases in the conditioned media were decreased. Since MMP-2 was not detectable in the conditioned media of MDA-MB-231 cells, and the gelatinolytic activities of the conditioned media were reduced only by MMP-9 neutralizing antibodies, it is most likely that the reduction of gelatinolytic activities by PPARgamma ligands and/or ATRA was due to the decrease of MMP-9 activities. Because MMP-9 was absolutely required in the transmigration of this cell line through Matrigel in our in vitro model as demonstrated by neutralizing antibodies against MMP-2 and -9, we concluded that down-regulation of gelatinase activities is, at least in part, responsible for the reduction of the invasive capacities of MDA-MB-231 cell line in vitro. Our results, for the first time, indicate that PPARgamma ligands may have therapeutic value for the treatment of highly invasive breast cancer by targeting its invasive behavior.
 ...
PMID:PPARgamma ligands and ATRA inhibit the invasion of human breast cancer cells in vitro. 1277 83

Peroxisome proliferator-activated receptor-gamma1 (PPARgamma1) is transactivated by a wide range of ligands in normal human mammary epithelial and breast cancer cells. Although transactivation of PPARgamma mediates the expression of genes that are markers of differentiation, its overexpression in cancers of the breast, thyroid, colon, and lung suggests its dysregulation may play a role in oncogenesis, cancer progression, or both. We report the overexpression of PPARgamma is caused by the use of a tumor-specific promoter in breast cancer cells that is distinct from the promoter used in normal epithelia. Thus, the increase in PPARgamma expression seen in breast cancer cells results from promoter recruitment, providing new insights into the expression and actions of PPARgamma in breast cancer.
 ...
PMID:The increased expression of peroxisome proliferator-activated receptor-gamma1 in human breast cancer is mediated by selective promoter usage. 1531 96

Peroxisome proliferator activated receptors (PPARs) are ligand-activated transcription factors with pleiotropic effects on cell fate and metabolism. Because of its anti-proliferative, pro-apoptotic and differentiation promoting activities, PPARgamma has been intensively evaluated as a target for anti-cancer therapy in preclinical models. However, PPARgamma has been reported to act both as a promoter and suppressor of neoplasia, and the role of PPARgamma activating ligands as well as antagonists in therapy remains controversial. In the past decade a new picture of tumors as a disease that involves changes in the non-cancerous tumor bed, including angiogenesis, inflammation and other stromal changes has emerged. PPARgamma has strong anti-inflammatory and anti-angiogenic effects, extending the repertoire of potential targets of PPARgamma ligands beyond cell autonomous mechanisms of cancer. The heterogeneous cellular targets and the biphasic effects of PPARgamma on various pro and anti-tumor processes may account for the apparent paradoxical effects of PPARgamma agonists. Here we review the action of PPARgamma agonists on angiogenesis and inflammation in the context of tumorigenesis as an integrated tissue process and discuss potential explanations for the conflicting effects of PPARgamma agonists on tumor progression and metastasis. Sorting out the various modes of action and defining their relative contribution in the context of tumor and host tissue as a heterogeneous target will therefore be crucial to understand the multi facetted effects of PPARgamma. This will be paramount if the potent biological activity of PPARgamma agonists are to be harnessed for cancer therapy.
 ...
PMID:PPARgamma as a therapeutic target for tumor angiogenesis and metastasis. 1608 79

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear hormone receptor family. In colon, this transcription factor is involved in differentiation of absorptive cells. PPARgamma participates also in colon carcinogenesis and cancer progression. Two isoforms, namely PPARgamma1 and PPARgamma2, have been described. Recently, new PPARgamma1 transcripts whose translation raises PPARgamma1 protein have been characterised. They differ from each other by combination of untranslated exons localised in the 5' UTR of the PPARG gene. Here, we studied whether such a diversity of PPARgamma transcripts occurs in human colon cell models. Based on bioinformatic analysis, putative untranslated exons were identified in the human PPARG gene. By RT-PCR analysis, we have demonstrated that several of these untranslated exons are included in PPARgamma transcripts from colon-derived cell lines or in those derived from other tissue. Using HT-29 cells, changes in PPARgamma1 mRNA levels were observed after treatment with PPARgamma agonists such as pioglitazone and troglitazone. These modifications correlated with particular PPARgamma transcripts excluding the untranslated exon A2. HT-29 cells treatment with actinomycin D or cycloheximide showed that the presence of PPARgamma mRNA including exon A2 was dependent on de novo protein synthesis. We concluded that diverse PPARgamma1 mRNA exist in colorectal cells. Levels of PPARgamma1 transcript varied according to the phenotype of colon cell model used. We suggest that regulation of PPARgamma1 mRNA levels could be dependent in part on the composition of untranslated exon(s) in the 5' UTR of PPARgamma1 mRNA.
 ...
PMID:Genetic analysis of peroxisome proliferator-activated receptor gamma1 splice variants in human colorectal cell lines. 1708 2

Peroxisome proliferator activated receptor (PPAR) gamma is a nuclear receptor involved primarily in lipid and glucose metabolism. PPARgamma is also expressed in several cancer types, and has been suggested to play a role in tumor progression. PPARgamma agonists have been shown to reduce the growth of colorectal carcinoma cells in culture and in xenograft models. Furthermore, the PPARgamma agonist thiazolidinedione has been shown to reduce metastasis in a murine model of rectal cancer. Since the chemokine receptor CXCR4 has emerged as an important player in tumorigenesis, particularly in the process of metastasis, we sought to determine if PPARgamma agonists might act in part by reducing CXCR4 expression. We found that rosiglitazone, a thiazolidinedione PPARgamma agonist used primarily in the treatment of type 2 diabetes, significantly reduced cell-surface expression of CXCR4 protein on HT-29 human colorectal carcinoma cells. This effect occurred at concentrations as low as 1 nM, and was first evident after 8 h of drug exposure. CXCR4 mRNA was also down-regulated after treatment with rosiglitazone, indicating that the effect occurs at the level of transcription. Four other thiazolidinedione compounds (ciglitazone, pioglitazone, troglitazone, and MCC555) also significantly reduced CXCR4 expression. To confirm the involvement of PPARgamma in thiazolidinedione-induced CXCR4 down-regulation, we used PPARgamma antagonists GW9662 and T0070907, both of which completely blocked the effect of rosiglitazone on CXCR4 expression. Furthermore, HT-29 cells in which PPARgamma expression was reduced using shRNA were less responsive to rosiglitazone. In conclusion, we have shown that thiazolidinedione compounds reduce CXCR4 mRNA and cell-surface protein expression in a PPARgamma-dependent manner.
 ...
PMID:Thiazolidinedione drugs down-regulate CXCR4 expression on human colorectal cancer cells in a peroxisome proliferator activated receptor gamma-dependent manner. 1739 24

Recently, we characterized tumor suppressor candidate 5 (Tusc5) as an adipocyte-neuron PPARgamma target gene. Our objective herein was to identify additional genes that display distinctly high expression in fat and neurons, because such a pattern could signal previously uncharacterized functional pathways shared in these disparate tissues. gamma-Synuclein, a marker of peripheral and select central nervous system neurons, was strongly expressed in white adipose tissue (WAT) and peripheral nervous system ganglia using bioinformatics and quantitative PCR approaches. Gamma-synuclein expression was determined during adipogenesis and in subcutaneous (SC) and visceral adipose tissue (VAT) from obese and nonobese humans. Gamma-synuclein mRNA increased from trace levels in preadipocytes to high levels in mature 3T3-L1 adipocytes and decreased approximately 50% following treatment with the PPARgamma agonist GW1929 (P < 0.01). Because gamma-synuclein limits growth arrest and is implicated in cancer progression in nonadipocytes, we suspected that expression would be increased in situations where WAT plasticity/adipocyte turnover are engaged. Consistent with this postulate, human WAT gamma-synuclein mRNA levels consistently increased in obesity and were higher in SC than in VAT; i.e. they increased approximately 1.7-fold in obese Pima Indian adipocytes (P = 0.003) and approximately 2-fold in SC and VAT of other obese cohorts relative to nonobese subjects. Expression correlated with leptin transcript levels in human SC and VAT (r = 0.887; P < 0.0001; n = 44). Gamma-synuclein protein was observed in rodent and human WAT but not in negative control liver. These results are consistent with the hypothesis that gamma-synuclein plays an important role in adipocyte physiology.
 ...
PMID:Gamma-synuclein is an adipocyte-neuron gene coordinately expressed with leptin and increased in human obesity. 1842 89

Peroxisome proliferators-activated receptors (PPARs) that are members of the nuclear receptor superfamily have three different isoforms: PPARalpha, PPARdelta, and PPARgamma. PPARs are ligand-activated transcription factors, and they are implicated in tumor progression, differentiation, and apoptosis. Activation of PPAR isoforms lead to both anticarcinogenesis and anti-inflammatory effect. It has so far identified many PPAR ligands including chemical composition and natural occurring. PPAR ligands are reported to activate PPAR signaling and exert cancer prevention and treatment in vitro and/or in vivo studies. Although the effects depend on the isoforms and the types of ligands, biological modulatory activities of PPARs in carcinogenesis and disease progression are attracted for control or combat cancer development. This short review summarizes currently available data on the role of PPAR ligands in carcinogenesis.
 ...
PMID:PPAR Ligands for Cancer Chemoprevention. 1848 18


1 2 3 4 Next >>