This paper reviews the distinctive roles played by the transcriptional coactivators CREB-binding protein(CBP) and p300 in Wnt/β-catenin signaling and cell physiology in colorectal cancer(CRC). Specifically, we focus ...This paper reviews the distinctive roles played by the transcriptional coactivators CREB-binding protein(CBP) and p300 in Wnt/β-catenin signaling and cell physiology in colorectal cancer(CRC). Specifically, we focus on the effects of CBP- and p300-mediated Wnt activity on(1) neoplastic progression;(2) the activities of butyrate, a breakdown product of dietary fiber, on cell signaling and colonic cell physiology;(3) the development of resistance to histone deacetylase inhibitors(HDACis), including butyrate and synthetic HDACis, in colonic cells; and(4) the physiology and number of cancer stem cells. Mutations of the Wnt/β-catenin signaling pathway initiate the majority of CRC cases, and we have shown that hyperactivation of this pathway by butyrate and other HDACis promotes CRC cell apoptosis. This activity by butyrate may in part explain the preventive action of fiber against CRC. However, individuals with a high-fiber diet may still develop neoplasia; therefore, resistance to the chemopreventive action of butyrate likely contributes to CRC. CBP or p300 may modify the ability of butyrate to influence colonic cell physiology since the two transcriptional coactivators affect Wnt signaling, and likely, its hyperactivation by butyrate. Also, CBP and p300 likely affect colonic tumorigenesis, as well as stem cell pluripotency. Improvement of CRC prevention and therapy requires a better understanding of the alterations in Wnt signaling and gene expression that underlie neoplastic progression, stem cell fate, and the development of resistance to butyrate and clinically relevant HDACis. Detailed knowledge of how CBP- and p300 modulate colonic cell physiology may lead to new approaches for anti-CRC prevention and therapeutics, particularly with respect to combinatorial therapy of CBP/p300 inhibitors with HDACis.展开更多
AIM: To investigate the effect of secreted frizzledrelated proteins(s FRPs) on CXC chemokine expression in human mesenchymal stem cells(h MSCs).METHODS: CXC chemokines such as CXCL5 and CXCL8 are induced in h MSCs dur...AIM: To investigate the effect of secreted frizzledrelated proteins(s FRPs) on CXC chemokine expression in human mesenchymal stem cells(h MSCs).METHODS: CXC chemokines such as CXCL5 and CXCL8 are induced in h MSCs during differentiation with osteogenic differentiation medium(OGM) and may be involved in angiogenic stimulation during bone repair. h MSCs were treated with conditioned medium(CM) from L-cells expressing non-canonical Wnt5 a protein, or with control CM from wild type L-cells, or directly with s FRPs for up to 10 d in culture. m RNA expression levels of both CXCL5 and CXCL8 were quantitated by real-time reverse transcriptase-polymerase chain reaction and secreted protein levels of these proteins determined by ELISA. Dose-(0-500 ng/m L) and time-response curves were generated for treatment with s FRP1. Signal transduction pathways were explored by western blot analysis with pan- or phosphorylation-specific antibodies, through use of specific pathway inhibitors, and through use of si RNAs targeting specific frizzled receptors(Fzd)-2 and 5 or thereceptor tyrosine kinase-like orphan receptor-2(Ro R2) prior to treatment with s FRPs. RESULTS: CM from L-cells expressing Wnt5 a, a noncanonical Wnt, stimulated an increase in CXCL5 m RNA expression and protein secretion in comparison to control L-cell CM. s FRP1, which should inhibit both canonical and non-canonical Wnt signaling, surprisingly enhanced the expression of CXCL5 at 7 and 10 d. Dickkopf1, an inhibitor of canonical Wnt signaling prevented the s FRPstimulated induction of CXCL5 and actually inhibited basal levels of CXCL5 expression at 7 but not at 10 d post treatment. In addition, all four s FRPs isoforms induced CXCL8 expression in a dose- and time-dependent manner with maximum expression at 7 d with treatment at 150 ng/m L. The largest increases in CXCL5 expression were seen from stimulation with s FRP1 or s FRP2. Analysis of mitogen-activated protein kinase signaling pathways in the presence of OGM showed s FRP1-induced phosphorylation of extracellular signal-regulated kinase(ERK)(p44/42) maximally at 5 min after s FRP1 addition, earlier than that found in OGM alone. Addition of a phospholipase C(PLC) inhibitor also prevented s FRPstimulated increases in CXCL8 m RNA. si RNA technology targeting the Fzd-2 and 5 and the non-canonical Fzd co-receptor Ro R2 also significantly decreased s FRP1/2-stimulated CXCL8 m RNA levels.CONCLUSION: CXC chemokine expression in h MSCs is controlled in part by s FRPs signaling through noncanonical Wnt involving Fzd2/5 and the ERK and PLC pathways.展开更多
基金Supported by National Institutes of Health(Bethesda,MD)National Cancer Institute,No.1R15CA149589-01
文摘This paper reviews the distinctive roles played by the transcriptional coactivators CREB-binding protein(CBP) and p300 in Wnt/β-catenin signaling and cell physiology in colorectal cancer(CRC). Specifically, we focus on the effects of CBP- and p300-mediated Wnt activity on(1) neoplastic progression;(2) the activities of butyrate, a breakdown product of dietary fiber, on cell signaling and colonic cell physiology;(3) the development of resistance to histone deacetylase inhibitors(HDACis), including butyrate and synthetic HDACis, in colonic cells; and(4) the physiology and number of cancer stem cells. Mutations of the Wnt/β-catenin signaling pathway initiate the majority of CRC cases, and we have shown that hyperactivation of this pathway by butyrate and other HDACis promotes CRC cell apoptosis. This activity by butyrate may in part explain the preventive action of fiber against CRC. However, individuals with a high-fiber diet may still develop neoplasia; therefore, resistance to the chemopreventive action of butyrate likely contributes to CRC. CBP or p300 may modify the ability of butyrate to influence colonic cell physiology since the two transcriptional coactivators affect Wnt signaling, and likely, its hyperactivation by butyrate. Also, CBP and p300 likely affect colonic tumorigenesis, as well as stem cell pluripotency. Improvement of CRC prevention and therapy requires a better understanding of the alterations in Wnt signaling and gene expression that underlie neoplastic progression, stem cell fate, and the development of resistance to butyrate and clinically relevant HDACis. Detailed knowledge of how CBP- and p300 modulate colonic cell physiology may lead to new approaches for anti-CRC prevention and therapeutics, particularly with respect to combinatorial therapy of CBP/p300 inhibitors with HDACis.
基金Supported by Merit Review Award from the United States,Department of Veterans Affairs Biomedical Laboratory Research and Development Service of the VA Office of Research and Development,No.I01BX000170
文摘AIM: To investigate the effect of secreted frizzledrelated proteins(s FRPs) on CXC chemokine expression in human mesenchymal stem cells(h MSCs).METHODS: CXC chemokines such as CXCL5 and CXCL8 are induced in h MSCs during differentiation with osteogenic differentiation medium(OGM) and may be involved in angiogenic stimulation during bone repair. h MSCs were treated with conditioned medium(CM) from L-cells expressing non-canonical Wnt5 a protein, or with control CM from wild type L-cells, or directly with s FRPs for up to 10 d in culture. m RNA expression levels of both CXCL5 and CXCL8 were quantitated by real-time reverse transcriptase-polymerase chain reaction and secreted protein levels of these proteins determined by ELISA. Dose-(0-500 ng/m L) and time-response curves were generated for treatment with s FRP1. Signal transduction pathways were explored by western blot analysis with pan- or phosphorylation-specific antibodies, through use of specific pathway inhibitors, and through use of si RNAs targeting specific frizzled receptors(Fzd)-2 and 5 or thereceptor tyrosine kinase-like orphan receptor-2(Ro R2) prior to treatment with s FRPs. RESULTS: CM from L-cells expressing Wnt5 a, a noncanonical Wnt, stimulated an increase in CXCL5 m RNA expression and protein secretion in comparison to control L-cell CM. s FRP1, which should inhibit both canonical and non-canonical Wnt signaling, surprisingly enhanced the expression of CXCL5 at 7 and 10 d. Dickkopf1, an inhibitor of canonical Wnt signaling prevented the s FRPstimulated induction of CXCL5 and actually inhibited basal levels of CXCL5 expression at 7 but not at 10 d post treatment. In addition, all four s FRPs isoforms induced CXCL8 expression in a dose- and time-dependent manner with maximum expression at 7 d with treatment at 150 ng/m L. The largest increases in CXCL5 expression were seen from stimulation with s FRP1 or s FRP2. Analysis of mitogen-activated protein kinase signaling pathways in the presence of OGM showed s FRP1-induced phosphorylation of extracellular signal-regulated kinase(ERK)(p44/42) maximally at 5 min after s FRP1 addition, earlier than that found in OGM alone. Addition of a phospholipase C(PLC) inhibitor also prevented s FRPstimulated increases in CXCL8 m RNA. si RNA technology targeting the Fzd-2 and 5 and the non-canonical Fzd co-receptor Ro R2 also significantly decreased s FRP1/2-stimulated CXCL8 m RNA levels.CONCLUSION: CXC chemokine expression in h MSCs is controlled in part by s FRPs signaling through noncanonical Wnt involving Fzd2/5 and the ERK and PLC pathways.
