High Pin1 expression is associated with tumor progression in colorectal cancer

BACKGROUND AND OBJECTIVES: Peptidyl prolyl cis-trans isomerase (Pin1) isomerizes only phosphorylated serine or threonine residues preceding proline in certain proteins and affects the protein function. Pin1 interacts with many signaling pathways, including Wnt signaling pathway that is crucial for colorectal tumorigenesis. Pin1 promotes cyclin D1 over-expression directly or through the stabilization of beta-catenin. Pin1 is over-expressed in some cancers such as prostate and breast cancers. This study aimed to determine whether Pin1 plays a role in colorectal tumorigenesis through the upregulation of beta-catenin and cyclin D1. METHODS: Immunohistochemical analyses were performed on 105 colorectal cancer tissue samples using anti-Pin1, anti-beta-catenin, and anti-cyclin D1 antibodies. We examined the relationships between Pin1 expression and clinicopathological factors, prognosis, and beta-catenin/cyclin D1 expression. RESULTS: High Pin1 expression was observed in 40 cases (38%) and positively correlated with histological type (P=0.0240), depth of invasion (P=0.0051), and staging (P=0.0027) of colorectal tumors. High Pin1 expression was also correlated with the over-expressions of both beta-catenin (P=0.0225) and cyclin D1 (P=0.0137). CONCLUSIONS: These results suggest that Pin1 plays an important role in colorectal tumorigenesis, presumably by increasing beta-catenin and cyclin D1 expressions.     

Molecular alterations associated with cyclin D1 overexpression in endometrial cancer

Cyclin D1 is frequently overexpressed in human neoplasias by gene rearrangement and amplification. In addition, Ras, PTEN and beta-catenin appear to modulate cyclin D1 levels. Since the causes of cyclin D1 overexpression are poorly understood in EC, we investigated whether or not this alteration is due to cyclin D1 gene amplification or to RAS, PTEN and beta-catenin mutation. We analyzed cyclin D1 expression in 18 AEHs, 65 EECs and 27 NEECs by immunohistochemistry as well as CCND1 gene amplification by FISH. In EECs, mutations in K-RAS, PTEN, beta-catenin and CCND1 were studied by PCR-SSCP and sequencing and MSI was evaluated by analyzing BAT-25 and BAT-26 microsatellites. Contingency tests were used to evaluate the relationships between variables. Cyclin D1 overexpression was not observed in AEHs but was present in 13.8% of EECs and 11.2% of NEECs (p = 0.031). CCND1 amplification was more frequent in NEECs (26.3%) than in EECs (2.1%) (p = 0.002). In EECs, cyclin D1 overexpression was not associated with mutations in K-RAS, PTEN or beta-catenin. However, in EECs with beta-catenin mutations, cyclin D1 was expressed mainly by cells expressing beta-catenin in the cytoplasm and nucleus but not in those with membranous expression. Finally, cyclin D1 overexpression was associated with MSI (p = 0.047). The molecular alterations associated with cyclin D1 overexpression differ in the 2 clinicopathologic types of EC. Cyclin D1 overexpression is associated with gene amplification in NEECs and with nucleocytoplasmic expression of beta-catenin and MSI in EECs.     

A plant oxylipin, 12-oxo-phytodienoic acid,inhibits proliferation of human breast cancer cells by targeting cyclin D1

Cyclin D1 overexpression has been associated with poor prognosis and resistance to therapy in human breast cancer. Thus, the development of therapeutic agents that selectively target cyclin D1 activity is of clinical interest. This study demonstrates that 12-oxo-phytodienoic acid (OPDA), a phytohormone with critical functions in growth and development in plants, induces growth arrest in MDA-MB-231 and T47D breast cancer cells. In response to OPDA treatment, the human breast cancer cell lines exhibit a progressive decline in cyclin D1 expression, which is tightly associated with the accumulation of hypophosphorylated form of the retinoblastoma protein (Rb) and G1 arrest. The decrease in cyclin D1 protein expression accompanies a dramatic decline in nuclear but not membranous beta-catenin expression and activation of glycogen synthase kinase-3-beta (GSK3beta) caused by inhibition of its serine-9 phosphorylation. The proteasome inhibitor MG132 blocks OPDA-mediated decrease in cyclin D1. In addition, the overexpression of T286A, a cyclin D1 mutant which is refractory to phosphorylation by GSK3beta and proteosomal degradation, is resistant to OPDA-mediated Rb dephosphorylation as well as G(1) cell cycle arrest. Thus, our results demonstrate that degradation of cyclin D1 protein is a key event in OPDA induced growth inhibition in breast cancer cells. These data provide the basic foundation for future efforts to develop OPDA-based approaches in the prevention and treatment of breast cancer and other types of cancer.     

Indomethacin induces differential expression of beta-catenin, gamma-catenin and T-cell factor target genes in human colorectal cancer cells.

Indomethacin-induced G(1) arrest and apoptosis of human colorectal cancer (CRC) cells is associated with a dose-dependent decrease in beta-catenin protein levels. Beta-catenin plays a pivotal role in the WNT signalling pathway and its expression is frequently dysregulated at early stages of colorectal carcinogenesis. The objective of this study was to investigate the effect of indomethacin on catenin expression and downstream WNT signalling events in human CRC cells. Beta-catenin, gamma-catenin and T-cell factor (TCF) target gene (cyclin D1, c-MYC and PPARdelta) expression was studied following indomethacin treatment of SW480 and HCT116 cells. Cyclin D1 was used as a model TCF target gene for analysis of beta-catenin-TCF-4 DNA binding and trans-activation. Indomethacin treatment was associated with a specific decrease in beta-catenin (but not gamma-catenin) expression. Resulting TCF target gene expression was gene specific (cyclin D1, decreased; c-MYC, increased; PPARdelta, no significant change). Cyclin D1 promoter analysis revealed that indomethacin disrupted formation of a beta-catenin-TCF-4-DNA complex. Indomethacin-induced G(1) arrest and apoptosis is associated with specific beta-catenin down-regulation in human CRC cells in vitro. Differential expression of TCF target genes following indomethacin treatment implies complex effects on multiple genes which play an important role in colorectal carcinogenesis.     

Crossregulation of NF-kappaB by the APC/GSK-3beta/beta-catenin pathway

Glycogen synthase kinase-3beta (GSK-3beta) and adenomatous polyposis coli (APC) play an important role in the regulation of beta-catenin. Inhibition of or defects in their functions can lead to activation of beta-catenin. beta-catenin has been recently found to interact with and inhibit nuclear factor kappa B (NF-kappaB). However, the regulatory roles of GSK-3beta/APC on the NF-kappaB signaling pathway are unknown because of their diverse effects. In this study, we investigated whether GSK-3beta/APC might regulate NF-kappaB activity through beta-catenin. We found that inhibition of GSK-3beta suppressed NF-kappaB activity, whereas reexpression of APC restored NF-kappaB activity in APC mutated cells. The regulatory effects were through beta-catenin because depletion of beta-catenin with small interfering RNA (siRNA) in the same systems reversed the effects. The regulatory relationship was further supported by the analysis of primary breast tumor tissues in vivo in which NF-kappaB target TRAF1 was inversely correlated with activated beta-catenin. Thus, APC/GSK-3beta, through beta-catenin, may crossregulate NF-kappaB signaling pathway.     

Effects of PEG-liposomal oxaliplatin on apoptosis, and expression of Cyclin A and Cyclin D1 in colorectal cancer cells

Oxaliplatin is one of the agents used against colorectal cancer. Using PEG-liposome encapsulated oxaliplatin may enhance the accumulation of drugs in tumor cells, inducing apoptosis. However, the mechanism of action of PEG-liposome encapsulated oxaliplatin remains unclear. SW480 human colorectal cancer cells were treated with empty PEG-liposomes, free oxaliplatin or PEG-liposomal oxaliplatin. Cell cycle and apoptosis were assessed using fluorescence confocal microscopy and terminal deoxynucleotidyl transferase-mediated dUTP-fluorescein nick-end-labeling (TUNEL). Western blotting was used to analyze the expression of pro-apoptotic, anti-apoptotic and cyclin proteins. We found that PEG-liposomal oxaliplatin induced a stronger apoptotic response than empty PEG-liposomes or free oxaliplatin. Moreover, expression of Cyclin D1 increased, whereas expression of Cyclin A decreased after treatment with PEG-liposomal oxaliplatin. Furthermore, the cell cycle was arrested in the G1 phase. The results presented here indicate that PEG-liposome entrapment of oxaliplatin enhances the anticancer potency of the chemotherapeutic agent. The effect of PEG-liposomal oxaliplatin on apoptosis of SW480 human colorectal cancer cells may be through regulation of expression of Cyclin A or Cyclin D1, as well as pro-apoptotic and anti-apoptotic proteins.     

2-Methoxyestradiol modulates beta-catenin in prostate cancer cells: a possible mediator of 2-methoxyestradiol-induced inhibition of cell growth

2-Methoxyestradiol (2-ME(2)) is a novel anticancer agent because of its ability to potentiate apoptotic cell death and inhibit cancer cell growth and angiogenesis. The modes of action of this agent, however, have not yet been fully elucidated. In our study, we have investigated whether 2-ME2 is able to modulate beta-catenin signaling in prostate cancer cells, which is one of the major players in cell-cell adhesion, proliferation, apoptosis and carcinogenesis. We found that beta-catenin levels were significantly upregulated by 2-ME(2) in a dose-dependent manner in androgen dependent and independent prostate cancer total cellular extracts. We further show that beta-catenin levels were significantly increased in the membrane fraction, while nuclear fractions of beta-catenin were downregulated in the 2-ME(2)-treated cells. Accumulation of dephospho-beta-catenin (nondegraded form) parallel with Bcl-2 and Cyclin D1 downregulation was also achieved after 2-ME(2) treatment. Moreover, we demonstrate that the beta-catenin production by 2-ME(2) is mediated through the MEK/ERK-2 signaling pathway. Collectively, these results suggest that the cytostatic effect of 2-ME(2) may be mediated through the prevention of the translocation of beta-catenin to the nucleus parallel with an increase in cell-cell adhesion by increasing membrane beta-catenin production, eventually preventing cell migration. Moreover, dephospho-beta-catenin accumulation by 2ME(2) in the cytoplasm may contribute to the induction of apoptosis of these cells. Finally, studies testing the efficacy of 2-ME(2) in human prostate cancer are warranted to determine whether the inhibition of the expected loss of membranous beta-catenin and the upregulation of nuclear beta-catenin can prevent prostate cancer development and progression.     

Cyclooxygenase inhibitors induce apoptosis in sinonasal cancer cells by increased expression of nonsteroidal anti-inflammatory drug-activated gene

Nonsteroidal anti-inflammatory drug-activated gene-1 (NAG-1) has recently been shown to be induced by nonsteroidal anti-inflammatory drugs (NSAIDs) and to have proapoptotic and antitumorigenic activities. Although sulindac sulfide induced apoptosis in sinonasal cancer cells, the relationship between NAG-1 and NSAIDs has not been determined. In this study, we investigated the induction of apoptosis in sinonasal cancer cells treated by various NSAIDs and the role of NAG-1 expression in this induction. The effect of NSAIDs on normal human nasal epithelial (NHNE) cells was also examined to evaluate their safety on normal cells. Finally, the in vivo anti-tumorigenic activity of NSAIDs in mice was investigated. In AMC-HN5 human sinonasal carcinoma cells, indomethacin was the most potent NAG-1 inducer and caused NAG-1 expression in a time- and dose-dependent manner. The induction of NAG-1 expression preceded the induction of apoptosis. Conditioned medium from NAG-1-overexpressing Drosophila cells inhibited proliferation of sinonasal cancer cells and induced apoptosis. In addition, in NAG-1 small interfering RNA-transfected cells, apoptosis induced by indomethacin was suppressed. In contrast, NAG-1 expression and apoptosis were not induced by NSAIDs or conditioned medium in NHNE cells. Furthermore, indomethacin induced a dose-dependent in vivo increase in the expression of NAG-1 mRNA in the mice tumors and the volume of xenograft tumors of AMC-HN5 cells in indomethacin-treated nude mice was reduced compared to that in control mice. In conclusion, indomethacin exerts proapoptotic and antitumorigenic effects in sinonasal cancer cells through the induction of NAG-1 and can be considered a safe and effective chemopreventive agent against sinonasal cancer.