Project description:Angiogenesis inhibitors, such as sunitinib, represent a promising strategy to improve glioblastoma (GBM) tumor response. In this study, we used the O6-methylguanine methyltransferase (MGMT)-negative GBM cell line U87MG stably transfected with MGMT (U87/MGMT) to assess whether MGMT expression affects the response to sunitinib. We showed that the addition of sunitinib to standard therapy (temozolomide [TMZ] and radiation therapy [RT]) significantly improved the response of MGMT positive but not of MGMT-negative cells. Gene expression profiling revealed alterations in the angiogenic profile, as well as differential expression of several receptor tyrosine kinases targeted by sunitinib. MGMT-positive cells displayed higher levels of vascular endothelial growth factor receptor 1 (VEGFR-1) compared with U87/EV cells, whereas they displayed decreased levels of VEGFR-2. Depleting MGMT using O6-benzylguanine suggested that the expression of these receptors was directly related to the MGMT status. Also, we showed that MGMT expression was associated with a dramatic increase in the soluble VEGFR-1/VEGFA ratio, thereby suggesting a decrease in bioactive VEGFA and a shift towards an antiangiogenic profile. The reduced angiogenic potential of MGMT-positive cells is supported by: (i) the decreased ability of their secreted factors to induce endothelial tube formation in vitro and (ii) their low tumorigenicity in vivo compared with the MGMT-negative cells. Our study is the first to show a direct link between MGMT expression and decreased angiogenicity and tumorigenicity of GBM cells and suggests the combination of sunitinib and standard therapy as an alternative strategy for GBM patients with MGMT-positive tumors. RNA was isolated from parental U87 (U87_EV) and MGMT-transfected U87 (U87_MGMT) triplicate. Pairwise gene expression differences were compared between the two cell lines. Features selected had more than 2-fold up-or down-regulated (P values of >05, unpaired Studentâs t-test with Bonferroni multiple testing correction) were identified. Database for annotation, visualization, and integrated discovery23 was used to identify enriched gene ontology (GO) biological themes.24 The GO data mining was conducted at a term specificity level 3.25 The EASE score was set at 0.05 and the minimum number of genes in a category was 5.

Project description:Transcriptome analysis was used to identify gene expression changes during development of sunitinib resistance in a renal cell carcinoma patient-derived xenograft (PDX) model. During the response phase, tumors exhibited a 91% reduction in volume, characterized by induction of TNFRSF1A, TNFAIP3, NFKB2, CCL2, CCL20, BIRC3, and MOAP1. Ingenuity Pathway Analysis indicated decreased expression of cell survival genes during tumor response to sunitinib. In this model, after 4 weeks of treatment, tumors developed resistance despite continued administration of the tyrosine kinase inhibitor (TKI) sunitinib (40 mg/kg/d p.o.). Resistance was associated with increased expression of VEGFA, EPO, IL-8, ANGPT2, TNFRSF12, MAPK3/7, MAPKBP1, and increased cell survival genes, suggesting activation of angiogenesis and MAPK/ERK pathways. Tumor lysate mRNA evaluated for murine gene expression to examine the contribution of host effects, indicated that tumor response was associated with downregulation of immune cell trafficking, cellular movement, and inflammatory response genes. During tumor escape, genes associated with cellular movement, inflammatory response, and immune cell trafficking were strongly induced, along with intratumoral accumulation of myeloid derived suppressor cells (MDSC), indicating a role for host factors during emergence of sunitinib resistance. The same PDX model was used to assess anti-tumor efficacy of sunitinib combined with MEK inhibitor (MEKi) PD-0325901 (4 mg/kg/d p.o.) using different schedules. The most effective treatment regimen was either continuous treatment with both drugs or switching from sunitinib to PD-0325901 monotherapy at d30, which reduced tumor volume by 78.6% (p=0.0241) and 88.5% (p=0.0068), respectively. The combination of MEKi with TKI (sunitinib, axitinib, or pazopanib) suppressed levels of phospho-MEK1/2 and phospho-ERK1/2, and decreased intratumoral MDSC. Thus, continuous treatment with sunitinib alone did not maintain tumor response, and addition of a MEKi abrogated resistance leading to prolonged survival. Study was comprised of three experimental groups (pre-treatment, response, escape). All tumors came from the same PDX model. There were four biological replicates in each group. Four mice were used, with each of the 3 groups per mouse. There were no control or reference samples.

Project description:Transcriptome analysis was used to identify gene expression changes during development of sunitinib resistance in a renal cell carcinoma patient-derived xenograft (PDX) model. During the response phase, tumors exhibited a 91% reduction in volume, characterized by induction of TNFRSF1A, TNFAIP3, NFKB2, CCL2, CCL20, BIRC3, and MOAP1. Ingenuity Pathway Analysis indicated decreased expression of cell survival genes during tumor response to sunitinib. In this model, after 4 weeks of treatment, tumors developed resistance despite continued administration of the tyrosine kinase inhibitor (TKI) sunitinib (40 mg/kg/d p.o.). Resistance was associated with increased expression of VEGFA, EPO, IL-8, ANGPT2, TNFRSF12, MAPK3/7, MAPKBP1, and increased cell survival genes, suggesting activation of angiogenesis and MAPK/ERK pathways. Tumor lysate mRNA evaluated for murine gene expression to examine the contribution of host effects, indicated that tumor response was associated with downregulation of immune cell trafficking, cellular movement, and inflammatory response genes. During tumor escape, genes associated with cellular movement, inflammatory response, and immune cell trafficking were strongly induced, along with intratumoral accumulation of myeloid derived suppressor cells (MDSC), indicating a role for host factors during emergence of sunitinib resistance. The same PDX model was used to assess anti-tumor efficacy of sunitinib combined with MEK inhibitor (MEKi) PD-0325901 (4 mg/kg/d p.o.) using different schedules. The most effective treatment regimen was either continuous treatment with both drugs or switching from sunitinib to PD-0325901 monotherapy at d30, which reduced tumor volume by 78.6% (p=0.0241) and 88.5% (p=0.0068), respectively. The combination of MEKi with TKI (sunitinib, axitinib, or pazopanib) suppressed levels of phospho-MEK1/2 and phospho-ERK1/2, and decreased intratumoral MDSC. Thus, continuous treatment with sunitinib alone did not maintain tumor response, and addition of a MEKi abrogated resistance leading to prolonged survival.

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