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Masabumi Shibuya - One of the best experts on this subject based on the ideXlab platform.
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Production of an anti-angiogenic factor sFLT1 is suppressed via promoter hypermethylation of FLT1 gene in choriocarcinoma cells.
BMC cancer, 2020Co-Authors: Tadashi Sasagawa, Atsushi Jinno-oue, Takeshi Nagamatsu, Kazuki Morita, Tetsushi Tsuruga, Mayuyo Mori-uchino, Tomoyuki Fujii, Masabumi ShibuyaAbstract:Soluble Fms-like tyrosine kinase-1 (sFLT1) as an anti-angiogenic factor is abundantly expressed in placental trophoblasts. Choriocarcinoma, a malignant tumor derived from trophoblasts, is known to be highly angiogenic and metastatic. However, the molecular mechanism underlying angiogenesis in choriocarcinoma pathogenesis remains unclear. We aimed to investigate the mRNA expression and DNA methylation status of the FLT1 gene in human choriocarcinoma cells and trophoblast cells. qRT-PCR, Western blotting and ELISA were conducted to evaluate the mRNA and protein expression levels of sFLT1. 5-aza-2′-deoxycytidine (5azadC) treatment and bisulfite sequencing were used to study the FLT1 gene promoter methylation. The effect of sFLT1 on choriocarcinoma growth and angiogenesis was evaluated in a xenograft mouse model. Expression of the FLT1 gene was strongly suppressed in choriocarcinoma cell lines compared with that in the primary trophoblasts. Treatment of choriocarcinoma cell lines with 5azadC, a DNA methyltransferase inhibitor, markedly increased in mRNA expression of three FLT1 splice variants and secretion of sFLT1 proteins. Bisulfite sequencing revealed that the CpG hypermethylation was observed at the FLT1 promoter region in choriocarcinoma cell lines and a human primary choriocarcinoma tissue but not in human trophoblast cells. Interestingly, in 5azadC-treated choriocarcinoma cell lines, sFLT1 mRNA expression and sFLT1 production were further elevated by hypoxic stimulation. Finally, as expected, sFLT1-expressing choriocarcinoma cells implanted into nude mice showed significantly slower tumor growth and reduced microvessel formation compared with GFP-expressing control choriocarcinoma cells. Inhibition of sFLT1 production by FLT1 silencing occurs via the hypermethylation of its promoter in choriocarcinoma cells. The stable expression of sFLT1 in choriocarcinoma cells resulted in the suppression of tumor growth and tumor vascularization in vivo. We suggest that the FLT1 gene may be a cell-type-specific tumor suppressor in choriocarcinoma cells.
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Production of an anti-angiogenic factor sFLT1 is suppressed via promoter hypermethylation of FLT1 gene in choriocarcinoma cells
2020Co-Authors: Tadashi Sasagawa, Atsushi Jinno-oue, Takeshi Nagamatsu, Kazuki Morita, Tetsushi Tsuruga, Mayuyo Mori-uchino, Tomoyuki Fujii, Masabumi ShibuyaAbstract:Abstract Background: Soluble Fms-like tyrosine kinase-1 (sFLT1) as an anti-angiogenic factor is abundantly expressed in placental trophoblasts. Choriocarcinoma, a malignant tumor derived from trophoblasts, is known to be highly angiogenic and metastatic. However, the molecular mechanism underlying angiogenesis in choriocarcinoma pathogenesis remains unclear. We aimed to investigate the mRNA expression and DNA methylation status of the FLT1 gene in human choriocarcinoma cells and trophoblast cells. Methods: qRT-PCR, Western blotting and ELISA were conducted to evaluate the mRNA and protein expression levels of sFLT1. 5-aza-2'-deoxycytidine (5azadC) treatment and bisulfite sequencing were used to study the FLT1 gene promoter methylation. The effect of sFLT1 on choriocarcinoma growth and angiogenesis was evaluated in a xenograft mouse model. Results: Expression of the FLT1 gene was strongly suppressed in choriocarcinoma cell lines compared with that in the primary trophoblasts. Treatment of choriocarcinoma cell lines with 5azadC, a DNA methyltransferase inhibitor, markedly increased in mRNA expression of three FLT1 splice variants and secretion of sFLT1 proteins. Bisulfite sequencing revealed that the CpG hypermethylation was observed at the FLT1 promoter region in choriocarcinoma cell lines and a human primary choriocarcinoma tissue but not in human trophoblast cells. Interestingly, in 5azadC-treated choriocarcinoma cell lines, sFLT1 mRNA expression and sFLT1 production were further elevated by hypoxic stimulation. Finally, as expected, sFLT1-expressing choriocarcinoma cells implanted into nude mice showed significantly slower tumor growth and reduced microvessel formation compared with GFP-expressing control choriocarcinoma cells. Conclusions: Inhibition of sFLT1 production by FLT1 silencing occurs via the hypermethylation of its promoter in choriocarcinoma cells. The stable expression of sFLT1 in choriocarcinoma cells resulted in the suppression of tumor growth and tumor vascularization in vivo . We suggest that the FLT1 gene may be a cell-type-specific tumor suppressor in choriocarcinoma cells.
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FLT1/VEGFR1 heterozygosity causes transient embryonic edema
Scientific reports, 2016Co-Authors: Yasunori Otowa, Masabumi Shibuya, Keigo Sano, Toshio Suda, Kazumasa Moriwaki, Masanori Shirakabe, Shigenobu Yonemura, Janet Rossant, Yoshihiro Kakeji, Masanori HirashimaAbstract:Vascular endothelial growth factor-A is a major player in vascular development and a potent vascular permeability factor under physiological and pathological conditions by binding to a decoy receptor FLT1 and its primary receptor Flk1. In this study, we show that FLT1 heterozygous (FLT1+/−) mouse embryos grow up to adult without life-threatening abnormalities but exhibit a transient embryonic edema around the nuchal and back regions, which is reminiscent of increased nuchal translucency in human fetuses. Vascular permeability is enhanced and an intricate infolding of the plasma membrane and huge vesicle-like structures are seen in FLT1+/− capillary endothelial cells. Flk1 tyrosine phosphorylation is elevated in FLT1+/− embryos, but Flk1 heterozygosity does not suppress embryonic edema caused by FLT1 heterozygosity. When FLT1 mutants are crossed with Aspp1−/− mice which exhibit a transient embryonic edema with delayed formation and dysfunction of lymphatic vessels, only 5.7% of FLT1+/−; Aspp1−/− mice survive, compared to expected ratio (25%). Our results demonstrate that FLT1 heterozygosity causes a transient embryonic edema and can be a risk factor for embryonic lethality in combination with other mutations causing non-lethal vascular phenotype.
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FLT1 vegfr1 heterozygosity causes transient embryonic edema
Scientific Reports, 2016Co-Authors: Yasunori Otowa, Masabumi Shibuya, Keigo Sano, Toshio Suda, Kazumasa Moriwaki, Masanori Shirakabe, Shigenobu Yonemura, Janet Rossant, Yoshihiro KakejiAbstract:Vascular endothelial growth factor-A is a major player in vascular development and a potent vascular permeability factor under physiological and pathological conditions by binding to a decoy receptor FLT1 and its primary receptor Flk1. In this study, we show that FLT1 heterozygous (FLT1+/−) mouse embryos grow up to adult without life-threatening abnormalities but exhibit a transient embryonic edema around the nuchal and back regions, which is reminiscent of increased nuchal translucency in human fetuses. Vascular permeability is enhanced and an intricate infolding of the plasma membrane and huge vesicle-like structures are seen in FLT1+/− capillary endothelial cells. Flk1 tyrosine phosphorylation is elevated in FLT1+/− embryos, but Flk1 heterozygosity does not suppress embryonic edema caused by FLT1 heterozygosity. When FLT1 mutants are crossed with Aspp1−/− mice which exhibit a transient embryonic edema with delayed formation and dysfunction of lymphatic vessels, only 5.7% of FLT1+/−; Aspp1−/− mice survive, compared to expected ratio (25%). Our results demonstrate that FLT1 heterozygosity causes a transient embryonic edema and can be a risk factor for embryonic lethality in combination with other mutations causing non-lethal vascular phenotype.
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rack1 regulates vegf FLT1 mediated cell migration via activation of a pi3k akt pathway
Journal of Biological Chemistry, 2011Co-Authors: Feng Wang, Rika Tsuchida, Mai Yamauchi, Masashi Muramatsu, Tsuyoshi Osawa, Masabumi ShibuyaAbstract:Vascular endothelial growth factor (VEGF) is vital to physiological as well as pathological angiogenesis, and regulates a variety of cellular functions, largely by activating its 2 receptors, fms-like tyrosine kinase (FLT1) and kinase domain receptor (KDR). KDR plays a critical role in the proliferation of endothelial cells by controlling VEGF-induced phospholipase Cγ-protein kinase C (PLCγ-PKC) signaling. The function of FLT1, however, remains to be clarified. Recent evidence has indicated that FLT1 regulates the VEGF-triggered migration of endothelial cells and macrophages. Here, we show that RACK1, a ubiquitously expressed scaffolding protein, functions as an important regulator of this process. We found that RACK1 (receptor for activated protein kinase C 1) binds to FLT1 in vitro. When the endogenous expression of RACK1 was attenuated by RNA interference, the VEGF-driven migration was remarkably suppressed whereas the proliferation was unaffected in a stable FLT1-expressing cell line, AG1-G1-FLT1. Further, we demonstrated that the VEGF/Flt-mediated migration of AG1-G1-FLT1 cells occurred mainly via the activation of the PI3 kinase (PI3K)/Akt and Rac1 pathways, and that RACK1 plays a crucial regulatory role in promoting PI3K/Akt-Rac1 activation.
Rika Tsuchida - One of the best experts on this subject based on the ideXlab platform.
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rack1 regulates vegf FLT1 mediated cell migration via activation of a pi3k akt pathway
Journal of Biological Chemistry, 2011Co-Authors: Feng Wang, Rika Tsuchida, Mai Yamauchi, Masashi Muramatsu, Tsuyoshi Osawa, Masabumi ShibuyaAbstract:Vascular endothelial growth factor (VEGF) is vital to physiological as well as pathological angiogenesis, and regulates a variety of cellular functions, largely by activating its 2 receptors, fms-like tyrosine kinase (FLT1) and kinase domain receptor (KDR). KDR plays a critical role in the proliferation of endothelial cells by controlling VEGF-induced phospholipase Cγ-protein kinase C (PLCγ-PKC) signaling. The function of FLT1, however, remains to be clarified. Recent evidence has indicated that FLT1 regulates the VEGF-triggered migration of endothelial cells and macrophages. Here, we show that RACK1, a ubiquitously expressed scaffolding protein, functions as an important regulator of this process. We found that RACK1 (receptor for activated protein kinase C 1) binds to FLT1 in vitro. When the endogenous expression of RACK1 was attenuated by RNA interference, the VEGF-driven migration was remarkably suppressed whereas the proliferation was unaffected in a stable FLT1-expressing cell line, AG1-G1-FLT1. Further, we demonstrated that the VEGF/Flt-mediated migration of AG1-G1-FLT1 cells occurred mainly via the activation of the PI3 kinase (PI3K)/Akt and Rac1 pathways, and that RACK1 plays a crucial regulatory role in promoting PI3K/Akt-Rac1 activation.
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RACK1 regulates VEGF/FLT1-mediated cell migration via activation of a PI3K/Akt pathway.
The Journal of biological chemistry, 2011Co-Authors: Feng Wang, Rika Tsuchida, Mai Yamauchi, Masashi Muramatsu, Tsuyoshi Osawa, Masabumi ShibuyaAbstract:Vascular endothelial growth factor (VEGF) is vital to physiological as well as pathological angiogenesis, and regulates a variety of cellular functions, largely by activating its 2 receptors, fms-like tyrosine kinase (FLT1) and kinase domain receptor (KDR). KDR plays a critical role in the proliferation of endothelial cells by controlling VEGF-induced phospholipase Cγ-protein kinase C (PLCγ-PKC) signaling. The function of FLT1, however, remains to be clarified. Recent evidence has indicated that FLT1 regulates the VEGF-triggered migration of endothelial cells and macrophages. Here, we show that RACK1, a ubiquitously expressed scaffolding protein, functions as an important regulator of this process. We found that RACK1 (receptor for activated protein kinase C 1) binds to FLT1 in vitro. When the endogenous expression of RACK1 was attenuated by RNA interference, the VEGF-driven migration was remarkably suppressed whereas the proliferation was unaffected in a stable FLT1-expressing cell line, AG1-G1-FLT1. Further, we demonstrated that the VEGF/Flt-mediated migration of AG1-G1-FLT1 cells occurred mainly via the activation of the PI3 kinase (PI3K)/Akt and Rac1 pathways, and that RACK1 plays a crucial regulatory role in promoting PI3K/Akt-Rac1 activation.
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cisplatin treatment increases survival and expansion of a highly tumorigenic side population fraction by upregulating vegf FLT1 autocrine signaling
Oncogene, 2008Co-Authors: Rika Tsuchida, Bikul Das, Herman Yeger, Gideon Koren, Masabumi Shibuya, Paul S. Thorner, Sylvain Baruchel, David MalkinAbstract:The cellular and molecular mechanisms of tumor progression following chemotherapy are largely unknown. Here, we demonstrate that cisplatin (CDDP) treatment upregulates VEGF and FLT1 expression leading to the survival and expansion of a highly tumorigenic fraction of side-population (SP) cells in osteosarcoma (HOS), neuroblastoma (SK-N-BE2) and rhabdomyosarcoma (RH-4) cell lines. In all three lines, we show that CDDP treatment increases levels of VEGF and FLT1 expression, and induces enhanced clonogenic capacity and increased expression of the 'stemness'-associated genes Nanog, Bmi-1 and Oct-4 in the SP fraction. In HOS, these changes are associated with the transformation of a non-tumorigenic osteosarcoma SP fraction to a highly tumorigenic phenotype. Inhibition of FLT1 led to complete reduction of tumorigenicity in the HOS SP fraction, and reduction of clonogenic capacity and expression of stemness genes in the SK-N-BE(2) and RH-4 SP fractions. Treatment with U0126, a specific inhibitor of MAPK/ERK1,2 completely downregulates CDDP-induced VEGF and FLT1 expression and induction/expansion of SP fraction in all three cell lines, indicating that these effects are mediated through MAPK/ERK1,2 signaling. In conclusion, we report a novel mechanism of CDDP-induced tumor progression, whereby the activation of VEGF/FLT1 autocrine signaling leads to the survival and expansion of a highly tumorigenic SP fraction.
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Cisplatin treatment increases survival and expansion of a highly tumorigenic side-population fraction by upregulating VEGF/FLT1 autocrine signaling
Oncogene, 2008Co-Authors: Rika Tsuchida, Bikul Das, Herman Yeger, Gideon Koren, Masabumi Shibuya, Paul S. Thorner, Sylvain Baruchel, David MalkinAbstract:The cellular and molecular mechanisms of tumor progression following chemotherapy are largely unknown. Here, we demonstrate that cisplatin (CDDP) treatment upregulates VEGF and FLT1 expression leading to the survival and expansion of a highly tumorigenic fraction of side-population (SP) cells in osteosarcoma (HOS), neuroblastoma (SK-N-BE2) and rhabdomyosarcoma (RH-4) cell lines. In all three lines, we show that CDDP treatment increases levels of VEGF and FLT1 expression, and induces enhanced clonogenic capacity and increased expression of the 'stemness'-associated genes Nanog, Bmi-1 and Oct-4 in the SP fraction. In HOS, these changes are associated with the transformation of a non-tumorigenic osteosarcoma SP fraction to a highly tumorigenic phenotype. Inhibition of FLT1 led to complete reduction of tumorigenicity in the HOS SP fraction, and reduction of clonogenic capacity and expression of stemness genes in the SK-N-BE(2) and RH-4 SP fractions. Treatment with U0126, a specific inhibitor of MAPK/ERK1,2 completely downregulates CDDP-induced VEGF and FLT1 expression and induction/expansion of SP fraction in all three cell lines, indicating that these effects are mediated through MAPK/ERK1,2 signaling. In conclusion, we report a novel mechanism of CDDP-induced tumor progression, whereby the activation of VEGF/FLT1 autocrine signaling leads to the survival and expansion of a highly tumorigenic SP fraction.
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a hypoxia driven vascular endothelial growth factor FLT1 autocrine loop interacts with hypoxia inducible factor 1α through mitogen activated protein kinase extracellular signal regulated kinase 1 2 pathway in neuroblastoma
Cancer Research, 2005Co-Authors: Bikul Das, Rika Tsuchida, Herman Yeger, Masabumi Shibuya, Paul S. Thorner, David Malkin, Risa Torkin, Matthew F W Gee, Sylvain BaruchelAbstract:FLT1, an “fms-like tyrosine kinase” receptor, has been suggested to play an active role in vascular endothelial growth factor (VEGF)–mediated autocrine signaling of tumor growth and angiogenesis. Here, we used a neuroblastoma model to investigate the role of VEGF/FLT1 signaling in hypoxia-mediated tumor cell survival, drug resistance, and in vivo angiogenesis. SK-N-BE(2), a highly malignant neuroblastoma cell line resistant to hypoxia-induced apoptosis expresses active FLT1 but lacks VEGFR2 expression. We found that 24-hour hypoxia (<0.1% O2) alone (no serum deprivation) showed sustained activation of extracellular signal-regulated kinase 1/2 (ERK1/2) associated with bcl-2 up-regulation and resistance to etoposide-induced (5 μmol/L) apoptosis. Treatment with anti-VEGF and anti-FLT1 antibodies inhibited ERK1/2 activation, down-regulated bcl-2, and reversed the hypoxia-mediated drug resistance to etoposide. Similar results were obtained with U0126 and ursolic acid, specific and nonspecific inhibitors of ERK1/2, respectively. We confirmed the protective role of FLT1 receptor by small interfering RNA knockout and FLT1 overexpression studies. Subsequently, we found that inhibition of VEGF/FLT1 autocrine signaling led to reduced hypoxia-inducible factor-1α (HIF-1α) phosphorylation. Furthermore, the reduced phosphorylation was associated with down-regulation of basic fibroblast growth factor, a downstream target of the HIF-1α and VEGF pathways. Our findings suggested an expanded autocrine loop between VEGF/FLT1 signaling and HIF-1α. We investigated the angiogenic activity of the loop in an in vivo Matrigel plug assay. The hypoxia-treated conditioned medium induced a strong angiogenic response, as well as the cooption of surrounding vessels into the plugs; ursolic acid inhibited the angiogenesis process. We also found that three other FLT1-expressing neuroblastoma cell lines show hypoxia-mediated drug resistance to etoposide, melphalan, doxorubicin, and cyclophosphamide. Taken together, we conclude that a hypoxia-driven VEGF/FLT1 autocrine loop interacts with HIF-1α through a mitogen-activated protein kinase/ERK1/2 pathway in neuroblastoma. The interaction, in the form of an autocrine loop, is required for the hypoxia-driven cell survival, drug resistance, and angiogenesis in neuroblastoma.
David Malkin - One of the best experts on this subject based on the ideXlab platform.
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cisplatin treatment increases survival and expansion of a highly tumorigenic side population fraction by upregulating vegf FLT1 autocrine signaling
Oncogene, 2008Co-Authors: Rika Tsuchida, Bikul Das, Herman Yeger, Gideon Koren, Masabumi Shibuya, Paul S. Thorner, Sylvain Baruchel, David MalkinAbstract:The cellular and molecular mechanisms of tumor progression following chemotherapy are largely unknown. Here, we demonstrate that cisplatin (CDDP) treatment upregulates VEGF and FLT1 expression leading to the survival and expansion of a highly tumorigenic fraction of side-population (SP) cells in osteosarcoma (HOS), neuroblastoma (SK-N-BE2) and rhabdomyosarcoma (RH-4) cell lines. In all three lines, we show that CDDP treatment increases levels of VEGF and FLT1 expression, and induces enhanced clonogenic capacity and increased expression of the 'stemness'-associated genes Nanog, Bmi-1 and Oct-4 in the SP fraction. In HOS, these changes are associated with the transformation of a non-tumorigenic osteosarcoma SP fraction to a highly tumorigenic phenotype. Inhibition of FLT1 led to complete reduction of tumorigenicity in the HOS SP fraction, and reduction of clonogenic capacity and expression of stemness genes in the SK-N-BE(2) and RH-4 SP fractions. Treatment with U0126, a specific inhibitor of MAPK/ERK1,2 completely downregulates CDDP-induced VEGF and FLT1 expression and induction/expansion of SP fraction in all three cell lines, indicating that these effects are mediated through MAPK/ERK1,2 signaling. In conclusion, we report a novel mechanism of CDDP-induced tumor progression, whereby the activation of VEGF/FLT1 autocrine signaling leads to the survival and expansion of a highly tumorigenic SP fraction.
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Cisplatin treatment increases survival and expansion of a highly tumorigenic side-population fraction by upregulating VEGF/FLT1 autocrine signaling
Oncogene, 2008Co-Authors: Rika Tsuchida, Bikul Das, Herman Yeger, Gideon Koren, Masabumi Shibuya, Paul S. Thorner, Sylvain Baruchel, David MalkinAbstract:The cellular and molecular mechanisms of tumor progression following chemotherapy are largely unknown. Here, we demonstrate that cisplatin (CDDP) treatment upregulates VEGF and FLT1 expression leading to the survival and expansion of a highly tumorigenic fraction of side-population (SP) cells in osteosarcoma (HOS), neuroblastoma (SK-N-BE2) and rhabdomyosarcoma (RH-4) cell lines. In all three lines, we show that CDDP treatment increases levels of VEGF and FLT1 expression, and induces enhanced clonogenic capacity and increased expression of the 'stemness'-associated genes Nanog, Bmi-1 and Oct-4 in the SP fraction. In HOS, these changes are associated with the transformation of a non-tumorigenic osteosarcoma SP fraction to a highly tumorigenic phenotype. Inhibition of FLT1 led to complete reduction of tumorigenicity in the HOS SP fraction, and reduction of clonogenic capacity and expression of stemness genes in the SK-N-BE(2) and RH-4 SP fractions. Treatment with U0126, a specific inhibitor of MAPK/ERK1,2 completely downregulates CDDP-induced VEGF and FLT1 expression and induction/expansion of SP fraction in all three cell lines, indicating that these effects are mediated through MAPK/ERK1,2 signaling. In conclusion, we report a novel mechanism of CDDP-induced tumor progression, whereby the activation of VEGF/FLT1 autocrine signaling leads to the survival and expansion of a highly tumorigenic SP fraction.
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a hypoxia driven vascular endothelial growth factor FLT1 autocrine loop interacts with hypoxia inducible factor 1α through mitogen activated protein kinase extracellular signal regulated kinase 1 2 pathway in neuroblastoma
Cancer Research, 2005Co-Authors: Bikul Das, Rika Tsuchida, Herman Yeger, Masabumi Shibuya, Paul S. Thorner, David Malkin, Risa Torkin, Matthew F W Gee, Sylvain BaruchelAbstract:FLT1, an “fms-like tyrosine kinase” receptor, has been suggested to play an active role in vascular endothelial growth factor (VEGF)–mediated autocrine signaling of tumor growth and angiogenesis. Here, we used a neuroblastoma model to investigate the role of VEGF/FLT1 signaling in hypoxia-mediated tumor cell survival, drug resistance, and in vivo angiogenesis. SK-N-BE(2), a highly malignant neuroblastoma cell line resistant to hypoxia-induced apoptosis expresses active FLT1 but lacks VEGFR2 expression. We found that 24-hour hypoxia (<0.1% O2) alone (no serum deprivation) showed sustained activation of extracellular signal-regulated kinase 1/2 (ERK1/2) associated with bcl-2 up-regulation and resistance to etoposide-induced (5 μmol/L) apoptosis. Treatment with anti-VEGF and anti-FLT1 antibodies inhibited ERK1/2 activation, down-regulated bcl-2, and reversed the hypoxia-mediated drug resistance to etoposide. Similar results were obtained with U0126 and ursolic acid, specific and nonspecific inhibitors of ERK1/2, respectively. We confirmed the protective role of FLT1 receptor by small interfering RNA knockout and FLT1 overexpression studies. Subsequently, we found that inhibition of VEGF/FLT1 autocrine signaling led to reduced hypoxia-inducible factor-1α (HIF-1α) phosphorylation. Furthermore, the reduced phosphorylation was associated with down-regulation of basic fibroblast growth factor, a downstream target of the HIF-1α and VEGF pathways. Our findings suggested an expanded autocrine loop between VEGF/FLT1 signaling and HIF-1α. We investigated the angiogenic activity of the loop in an in vivo Matrigel plug assay. The hypoxia-treated conditioned medium induced a strong angiogenic response, as well as the cooption of surrounding vessels into the plugs; ursolic acid inhibited the angiogenesis process. We also found that three other FLT1-expressing neuroblastoma cell lines show hypoxia-mediated drug resistance to etoposide, melphalan, doxorubicin, and cyclophosphamide. Taken together, we conclude that a hypoxia-driven VEGF/FLT1 autocrine loop interacts with HIF-1α through a mitogen-activated protein kinase/ERK1/2 pathway in neuroblastoma. The interaction, in the form of an autocrine loop, is required for the hypoxia-driven cell survival, drug resistance, and angiogenesis in neuroblastoma.
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A Hypoxia-Driven Vascular Endothelial Growth Factor/FLT1 Autocrine Loop Interacts with Hypoxia-Inducible Factor-1α through Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase 1/2 Pathway in Neuroblastoma
Cancer research, 2005Co-Authors: Bikul Das, Rika Tsuchida, Herman Yeger, Masabumi Shibuya, Paul S. Thorner, David Malkin, Risa Torkin, Matthew F W Gee, Sylvain BaruchelAbstract:FLT1, an “fms-like tyrosine kinase” receptor, has been suggested to play an active role in vascular endothelial growth factor (VEGF)–mediated autocrine signaling of tumor growth and angiogenesis. Here, we used a neuroblastoma model to investigate the role of VEGF/FLT1 signaling in hypoxia-mediated tumor cell survival, drug resistance, and in vivo angiogenesis. SK-N-BE(2), a highly malignant neuroblastoma cell line resistant to hypoxia-induced apoptosis expresses active FLT1 but lacks VEGFR2 expression. We found that 24-hour hypoxia (
Sylvain Baruchel - One of the best experts on this subject based on the ideXlab platform.
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cisplatin treatment increases survival and expansion of a highly tumorigenic side population fraction by upregulating vegf FLT1 autocrine signaling
Oncogene, 2008Co-Authors: Rika Tsuchida, Bikul Das, Herman Yeger, Gideon Koren, Masabumi Shibuya, Paul S. Thorner, Sylvain Baruchel, David MalkinAbstract:The cellular and molecular mechanisms of tumor progression following chemotherapy are largely unknown. Here, we demonstrate that cisplatin (CDDP) treatment upregulates VEGF and FLT1 expression leading to the survival and expansion of a highly tumorigenic fraction of side-population (SP) cells in osteosarcoma (HOS), neuroblastoma (SK-N-BE2) and rhabdomyosarcoma (RH-4) cell lines. In all three lines, we show that CDDP treatment increases levels of VEGF and FLT1 expression, and induces enhanced clonogenic capacity and increased expression of the 'stemness'-associated genes Nanog, Bmi-1 and Oct-4 in the SP fraction. In HOS, these changes are associated with the transformation of a non-tumorigenic osteosarcoma SP fraction to a highly tumorigenic phenotype. Inhibition of FLT1 led to complete reduction of tumorigenicity in the HOS SP fraction, and reduction of clonogenic capacity and expression of stemness genes in the SK-N-BE(2) and RH-4 SP fractions. Treatment with U0126, a specific inhibitor of MAPK/ERK1,2 completely downregulates CDDP-induced VEGF and FLT1 expression and induction/expansion of SP fraction in all three cell lines, indicating that these effects are mediated through MAPK/ERK1,2 signaling. In conclusion, we report a novel mechanism of CDDP-induced tumor progression, whereby the activation of VEGF/FLT1 autocrine signaling leads to the survival and expansion of a highly tumorigenic SP fraction.
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Cisplatin treatment increases survival and expansion of a highly tumorigenic side-population fraction by upregulating VEGF/FLT1 autocrine signaling
Oncogene, 2008Co-Authors: Rika Tsuchida, Bikul Das, Herman Yeger, Gideon Koren, Masabumi Shibuya, Paul S. Thorner, Sylvain Baruchel, David MalkinAbstract:The cellular and molecular mechanisms of tumor progression following chemotherapy are largely unknown. Here, we demonstrate that cisplatin (CDDP) treatment upregulates VEGF and FLT1 expression leading to the survival and expansion of a highly tumorigenic fraction of side-population (SP) cells in osteosarcoma (HOS), neuroblastoma (SK-N-BE2) and rhabdomyosarcoma (RH-4) cell lines. In all three lines, we show that CDDP treatment increases levels of VEGF and FLT1 expression, and induces enhanced clonogenic capacity and increased expression of the 'stemness'-associated genes Nanog, Bmi-1 and Oct-4 in the SP fraction. In HOS, these changes are associated with the transformation of a non-tumorigenic osteosarcoma SP fraction to a highly tumorigenic phenotype. Inhibition of FLT1 led to complete reduction of tumorigenicity in the HOS SP fraction, and reduction of clonogenic capacity and expression of stemness genes in the SK-N-BE(2) and RH-4 SP fractions. Treatment with U0126, a specific inhibitor of MAPK/ERK1,2 completely downregulates CDDP-induced VEGF and FLT1 expression and induction/expansion of SP fraction in all three cell lines, indicating that these effects are mediated through MAPK/ERK1,2 signaling. In conclusion, we report a novel mechanism of CDDP-induced tumor progression, whereby the activation of VEGF/FLT1 autocrine signaling leads to the survival and expansion of a highly tumorigenic SP fraction.
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a hypoxia driven vascular endothelial growth factor FLT1 autocrine loop interacts with hypoxia inducible factor 1α through mitogen activated protein kinase extracellular signal regulated kinase 1 2 pathway in neuroblastoma
Cancer Research, 2005Co-Authors: Bikul Das, Rika Tsuchida, Herman Yeger, Masabumi Shibuya, Paul S. Thorner, David Malkin, Risa Torkin, Matthew F W Gee, Sylvain BaruchelAbstract:FLT1, an “fms-like tyrosine kinase” receptor, has been suggested to play an active role in vascular endothelial growth factor (VEGF)–mediated autocrine signaling of tumor growth and angiogenesis. Here, we used a neuroblastoma model to investigate the role of VEGF/FLT1 signaling in hypoxia-mediated tumor cell survival, drug resistance, and in vivo angiogenesis. SK-N-BE(2), a highly malignant neuroblastoma cell line resistant to hypoxia-induced apoptosis expresses active FLT1 but lacks VEGFR2 expression. We found that 24-hour hypoxia (<0.1% O2) alone (no serum deprivation) showed sustained activation of extracellular signal-regulated kinase 1/2 (ERK1/2) associated with bcl-2 up-regulation and resistance to etoposide-induced (5 μmol/L) apoptosis. Treatment with anti-VEGF and anti-FLT1 antibodies inhibited ERK1/2 activation, down-regulated bcl-2, and reversed the hypoxia-mediated drug resistance to etoposide. Similar results were obtained with U0126 and ursolic acid, specific and nonspecific inhibitors of ERK1/2, respectively. We confirmed the protective role of FLT1 receptor by small interfering RNA knockout and FLT1 overexpression studies. Subsequently, we found that inhibition of VEGF/FLT1 autocrine signaling led to reduced hypoxia-inducible factor-1α (HIF-1α) phosphorylation. Furthermore, the reduced phosphorylation was associated with down-regulation of basic fibroblast growth factor, a downstream target of the HIF-1α and VEGF pathways. Our findings suggested an expanded autocrine loop between VEGF/FLT1 signaling and HIF-1α. We investigated the angiogenic activity of the loop in an in vivo Matrigel plug assay. The hypoxia-treated conditioned medium induced a strong angiogenic response, as well as the cooption of surrounding vessels into the plugs; ursolic acid inhibited the angiogenesis process. We also found that three other FLT1-expressing neuroblastoma cell lines show hypoxia-mediated drug resistance to etoposide, melphalan, doxorubicin, and cyclophosphamide. Taken together, we conclude that a hypoxia-driven VEGF/FLT1 autocrine loop interacts with HIF-1α through a mitogen-activated protein kinase/ERK1/2 pathway in neuroblastoma. The interaction, in the form of an autocrine loop, is required for the hypoxia-driven cell survival, drug resistance, and angiogenesis in neuroblastoma.
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A Hypoxia-Driven Vascular Endothelial Growth Factor/FLT1 Autocrine Loop Interacts with Hypoxia-Inducible Factor-1α through Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase 1/2 Pathway in Neuroblastoma
Cancer research, 2005Co-Authors: Bikul Das, Rika Tsuchida, Herman Yeger, Masabumi Shibuya, Paul S. Thorner, David Malkin, Risa Torkin, Matthew F W Gee, Sylvain BaruchelAbstract:FLT1, an “fms-like tyrosine kinase” receptor, has been suggested to play an active role in vascular endothelial growth factor (VEGF)–mediated autocrine signaling of tumor growth and angiogenesis. Here, we used a neuroblastoma model to investigate the role of VEGF/FLT1 signaling in hypoxia-mediated tumor cell survival, drug resistance, and in vivo angiogenesis. SK-N-BE(2), a highly malignant neuroblastoma cell line resistant to hypoxia-induced apoptosis expresses active FLT1 but lacks VEGFR2 expression. We found that 24-hour hypoxia (
Bikul Das - One of the best experts on this subject based on the ideXlab platform.
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cisplatin treatment increases survival and expansion of a highly tumorigenic side population fraction by upregulating vegf FLT1 autocrine signaling
Oncogene, 2008Co-Authors: Rika Tsuchida, Bikul Das, Herman Yeger, Gideon Koren, Masabumi Shibuya, Paul S. Thorner, Sylvain Baruchel, David MalkinAbstract:The cellular and molecular mechanisms of tumor progression following chemotherapy are largely unknown. Here, we demonstrate that cisplatin (CDDP) treatment upregulates VEGF and FLT1 expression leading to the survival and expansion of a highly tumorigenic fraction of side-population (SP) cells in osteosarcoma (HOS), neuroblastoma (SK-N-BE2) and rhabdomyosarcoma (RH-4) cell lines. In all three lines, we show that CDDP treatment increases levels of VEGF and FLT1 expression, and induces enhanced clonogenic capacity and increased expression of the 'stemness'-associated genes Nanog, Bmi-1 and Oct-4 in the SP fraction. In HOS, these changes are associated with the transformation of a non-tumorigenic osteosarcoma SP fraction to a highly tumorigenic phenotype. Inhibition of FLT1 led to complete reduction of tumorigenicity in the HOS SP fraction, and reduction of clonogenic capacity and expression of stemness genes in the SK-N-BE(2) and RH-4 SP fractions. Treatment with U0126, a specific inhibitor of MAPK/ERK1,2 completely downregulates CDDP-induced VEGF and FLT1 expression and induction/expansion of SP fraction in all three cell lines, indicating that these effects are mediated through MAPK/ERK1,2 signaling. In conclusion, we report a novel mechanism of CDDP-induced tumor progression, whereby the activation of VEGF/FLT1 autocrine signaling leads to the survival and expansion of a highly tumorigenic SP fraction.
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Cisplatin treatment increases survival and expansion of a highly tumorigenic side-population fraction by upregulating VEGF/FLT1 autocrine signaling
Oncogene, 2008Co-Authors: Rika Tsuchida, Bikul Das, Herman Yeger, Gideon Koren, Masabumi Shibuya, Paul S. Thorner, Sylvain Baruchel, David MalkinAbstract:The cellular and molecular mechanisms of tumor progression following chemotherapy are largely unknown. Here, we demonstrate that cisplatin (CDDP) treatment upregulates VEGF and FLT1 expression leading to the survival and expansion of a highly tumorigenic fraction of side-population (SP) cells in osteosarcoma (HOS), neuroblastoma (SK-N-BE2) and rhabdomyosarcoma (RH-4) cell lines. In all three lines, we show that CDDP treatment increases levels of VEGF and FLT1 expression, and induces enhanced clonogenic capacity and increased expression of the 'stemness'-associated genes Nanog, Bmi-1 and Oct-4 in the SP fraction. In HOS, these changes are associated with the transformation of a non-tumorigenic osteosarcoma SP fraction to a highly tumorigenic phenotype. Inhibition of FLT1 led to complete reduction of tumorigenicity in the HOS SP fraction, and reduction of clonogenic capacity and expression of stemness genes in the SK-N-BE(2) and RH-4 SP fractions. Treatment with U0126, a specific inhibitor of MAPK/ERK1,2 completely downregulates CDDP-induced VEGF and FLT1 expression and induction/expansion of SP fraction in all three cell lines, indicating that these effects are mediated through MAPK/ERK1,2 signaling. In conclusion, we report a novel mechanism of CDDP-induced tumor progression, whereby the activation of VEGF/FLT1 autocrine signaling leads to the survival and expansion of a highly tumorigenic SP fraction.
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a hypoxia driven vascular endothelial growth factor FLT1 autocrine loop interacts with hypoxia inducible factor 1α through mitogen activated protein kinase extracellular signal regulated kinase 1 2 pathway in neuroblastoma
Cancer Research, 2005Co-Authors: Bikul Das, Rika Tsuchida, Herman Yeger, Masabumi Shibuya, Paul S. Thorner, David Malkin, Risa Torkin, Matthew F W Gee, Sylvain BaruchelAbstract:FLT1, an “fms-like tyrosine kinase” receptor, has been suggested to play an active role in vascular endothelial growth factor (VEGF)–mediated autocrine signaling of tumor growth and angiogenesis. Here, we used a neuroblastoma model to investigate the role of VEGF/FLT1 signaling in hypoxia-mediated tumor cell survival, drug resistance, and in vivo angiogenesis. SK-N-BE(2), a highly malignant neuroblastoma cell line resistant to hypoxia-induced apoptosis expresses active FLT1 but lacks VEGFR2 expression. We found that 24-hour hypoxia (<0.1% O2) alone (no serum deprivation) showed sustained activation of extracellular signal-regulated kinase 1/2 (ERK1/2) associated with bcl-2 up-regulation and resistance to etoposide-induced (5 μmol/L) apoptosis. Treatment with anti-VEGF and anti-FLT1 antibodies inhibited ERK1/2 activation, down-regulated bcl-2, and reversed the hypoxia-mediated drug resistance to etoposide. Similar results were obtained with U0126 and ursolic acid, specific and nonspecific inhibitors of ERK1/2, respectively. We confirmed the protective role of FLT1 receptor by small interfering RNA knockout and FLT1 overexpression studies. Subsequently, we found that inhibition of VEGF/FLT1 autocrine signaling led to reduced hypoxia-inducible factor-1α (HIF-1α) phosphorylation. Furthermore, the reduced phosphorylation was associated with down-regulation of basic fibroblast growth factor, a downstream target of the HIF-1α and VEGF pathways. Our findings suggested an expanded autocrine loop between VEGF/FLT1 signaling and HIF-1α. We investigated the angiogenic activity of the loop in an in vivo Matrigel plug assay. The hypoxia-treated conditioned medium induced a strong angiogenic response, as well as the cooption of surrounding vessels into the plugs; ursolic acid inhibited the angiogenesis process. We also found that three other FLT1-expressing neuroblastoma cell lines show hypoxia-mediated drug resistance to etoposide, melphalan, doxorubicin, and cyclophosphamide. Taken together, we conclude that a hypoxia-driven VEGF/FLT1 autocrine loop interacts with HIF-1α through a mitogen-activated protein kinase/ERK1/2 pathway in neuroblastoma. The interaction, in the form of an autocrine loop, is required for the hypoxia-driven cell survival, drug resistance, and angiogenesis in neuroblastoma.
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A Hypoxia-Driven Vascular Endothelial Growth Factor/FLT1 Autocrine Loop Interacts with Hypoxia-Inducible Factor-1α through Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase 1/2 Pathway in Neuroblastoma
Cancer research, 2005Co-Authors: Bikul Das, Rika Tsuchida, Herman Yeger, Masabumi Shibuya, Paul S. Thorner, David Malkin, Risa Torkin, Matthew F W Gee, Sylvain BaruchelAbstract:FLT1, an “fms-like tyrosine kinase” receptor, has been suggested to play an active role in vascular endothelial growth factor (VEGF)–mediated autocrine signaling of tumor growth and angiogenesis. Here, we used a neuroblastoma model to investigate the role of VEGF/FLT1 signaling in hypoxia-mediated tumor cell survival, drug resistance, and in vivo angiogenesis. SK-N-BE(2), a highly malignant neuroblastoma cell line resistant to hypoxia-induced apoptosis expresses active FLT1 but lacks VEGFR2 expression. We found that 24-hour hypoxia (