5-fluorouracil (5FU) and oxaliplatin are standard therapy for metastatic colorectal cancer (CRC), but the development of chemoresistance is inevitable. Since cancer stem cells (CSCs) are hypothesized to be chemoresistant, we investigated CSC properties in newly developed chemoresistant CRC cell lines and sought to identify targets for therapy. The human CRC cell line HT29 was exposed to increasing doses of 5FU (HT29/5FU-R) or oxaliplatin (HT29/Ox) to achieve resistance at clinically relevant doses. Western blotting and flow cytometry were done to determine molecular alterations. The insulin-like growth factor 1 receptor (IGF-1R) monoclonal antibody (MoAb) AVE-1642 was used to inhibit signaling in vitro and in vivo using murine xenograft models. HT29/5FU-R and HT29/OxR demonstrated 16- to 30-fold enrichment of CD133+ cells and 2-fold enrichment of CD44+ cells (putative CRC CSC markers). Resistant cells were enriched 5- to 22-fold for double-positive (CD133+/CD44+) cells. Consistent with the CSC phenotype, resistant cells exhibited a decrease in cellular proliferation in vitro (47–59%; p<0.05). Phosphorylated and total IGF-1R levels were increased in resistant cell lines. HT29/5FU-R and HT29/OxR cells were ~5-fold more responsive to IGF-1R inhibition relative to parental cells (p<0.01) in vitro. Tumors derived from HT29/OxR cells demonstrated significantly greater growth inhibition in response to an IGF-1R MoAB than did parental cells (p<0.05). Chemoresistant CRC cells are enriched for CSC markers and the CSC phenotype. Chemotherapy-induced IGF-1R activation provided for enhanced sensitivity to IGF-1R targeted therapy. Identification of CSC targets presents a novel therapeutic approach in this disease.

Endoglin (CD105) is an accessory protein of the transforming growth factor-h receptor system expressed on vascular endothelial cells. Mutation of the endoglin gene is associated with hereditary hemorrhagic telangiectasias, or Osler-Weber-Rendu syndrome, and has been studied extensively in the context of this disease.The expression of endoglin is elevated on the endothelial cells of healing wounds, developing embryos, inflammatory tissues, and solid tumors. Endoglin is a marker of activated endothelium, and its vascular expression is limited to proliferating cells. Recent studies identified endoglin expression in several solid tumor types, with the level of expression correlating with various clinicopathologic factors including decreased survival and presence of metastases. Attempts to target endoglin and the cells that express this protein in tumor-bearing mice have yielded promising results.

NRP2 on colorectal carcinoma cells is important for tumor growth and is a potential therapeutic target in human cancers where it is expressed.

Purpose. Neuropilin-2 (NRP-2) is a coreceptor for vascular endothelial growth factor (VEGF) on endothelial cells. NRP-2 is overexpressed in pancreatic ductal adenocarcinoma (PDAC) cells relative to nonmalignant ductal epithelium.This study determined the role of NRP-2 in PDAC cells. Experimental Design. NRP-2 expression was reduced in PDAC cells with stable short-hairpin RNA (shRNA) transfection. Western blotting was done to evaluate signaling intermediates. Migration and invasion studies were carried out in Boyden chambers. Anchorage-independent growth was assessed by soft-agar colony formation. In vivo growth was evaluated using murine subcutaneous and orthotopic xenograft models. Immunohistochemical analysis evaluated in vivo proliferation and angiogenesis. Results. shRNA-NRP-2 decreased NRP-2 levels without affecting neuropilin-1 levels. Akt activation was decreased in clones with reduced NRP-2 (shRNA-NRP-2). shRNA-NRP-2 cells showed decreased migration, invasion, and anchorage-independent growth compared with control cells. In vitro proliferation rates were similar in control-and shRNA-transfected cells. Subcutaneous and orthotopic xenografts from shRNA-transfected cells were significantly smaller than those resulting from control-transfected cells (P < 0.05). Furthermore, shRNA-NRP-2 tumors exhibited less cellular proliferation and decreased microvascular area relative to control tumors (P < 0.05). Constitutive expression of the angiogenic mediator Jagged-1 was reduced in shRNA-NRP-2 cells, whereas vascular endothelial growth factor levels were unchanged. Conclusion. Reduction of NRP-2 expression in PDAC cells decreased survival signaling, migration, invasion, and ability to grow under anchorage-independent conditions. In vivo, reduction of NRP-2 led to decreased growth of xenograft tumors and decreased vascular area, which was associated with decreased Jagged-1levels. NRP-2 is a potential therapeutic target on PDAC cells.

p -type ZnO films have been fabricated on a (0001) Al2O3 substrate, using Ag2O as a silver dopant by pulsed laser deposition. The structural property of those films is systematically characterized by observing the shift of (0002) peak to investigate the substitution of Ag+ for Zn+. Narrow deposition temperature for Ag-doped p-type ZnO films has been obtained in the range of 200–250°C with the hole concentration of 4.9×1016–6.0×1017cm−3. A neutral acceptor bound exciton has been clearly observed by photoluminescence emitted at 3.317eV in Ag-doped p-type ZnO thin films.