Contribute to angiogenesis and redirect the role of immune cells. Angiogenesis has long been understood to be an important part of tumorigenesis and many studies have been done to block this process [32]. While important angiogenic factors have been identified such as VEGF, therapeutics against the VEGF signaling pathway have not been proven to be universally successful. Indeed, many cancers are resistant to anti-VEGF therapy or become refractory to administration of these therapies, resulting inPK2/Bv8/PROK2 Antagonist Suppresses TumorigenesisFigure 4. PKRA7 GDC-0084 site enhances the efficacy of chemotherapeutic drugs 1531364 to reduce glioblastoma and pancreatic xenograft tumor growth. (A) Kaplan-Meier curve of nude mice after temozolomide and PKRA7 treatment following IC injection of 16104 D456MG cells. Treatment with 10 mg/ kg temozolomide or control started 3 days after IC injection for a total of 5 consecutive daily treatments. Treatment with PKRA7 or control started 7 days after IC injection and continued for the duration of experiment. 5 mice per condition. (B) AsPc-1 cells were SC injected into nude mice, and control (n = 10) or PKRA7 (n = 10) treatment was commenced when tumors were visible (7 days). Treatment with 100 mg/kg gemcitabine (n = 10) or control (n = 10) started 7 days after tumor implantation and was administered every 4 days for two weeks for a total of 4 treatments (#). Measurements were taken every 3 days. 5 mice per condition. (C) Average tumor weight of control, gemcitabine, PKRA7 and gemcitabine plus PKRA7-treated mouse tumors after their removal (*p#0.05). doi:10.1371/journal.pone.0054916.grecurrence that is sometimes more aggressive than the primary tumor [14,16,33?8]. There is a need to identify and target additional signaling order GDC-0152 pathways that may contribute to angiogenesis or other processes that have been shown to be important for tumor progression such as macrophage infiltration. PK2 and its receptors are part of a signaling pathway involved in myeloid cell mobilization [8]. Multiple studies have shown that the CD11b+Gr1+ myeloid precursor cells can contribute to angiogenesis and tumorigenesis in a variety of cancer types [8,37,39]. Macrophages derived from those precursor cells in the tumor microenvironment can also secrete cytokines that directly affect tumor cell growth. In recent studies, the anti-tumor efficacy of an anti-PK2 antibody has been compared to treatment with an anti-VEGF antibody and found to be nearly as effective in preventing disease progression of a transgenic mouse model of pancreatic b-cell tumorigenesis, while the combination of the two antibodies showed an even morepronounced effect in inhibiting subcutaneous growth of different human cancer cell lines (colon cancer, rhabdomyosarcoma) and mouse tumor 24786787 cells (mastocytoma, lymphoma) [8,39]. Anti-PK2 antibody treatment also reduced the number of circulating and tumor-infiltrating CD11b+Gr1+ myeloid cells, including bone marrow-derived macrophages, which have been shown to mediate refractoriness to anti-VEGF therapies in several mouse xenograft tumor models [8,37]. Those studies have indicated PK2 as a legitimate target for cancer therapy. Antibody-based therapies represent a significant portion of cancer treatment options in today’s clinics. However, studies with patients and mouse models of glioblastoma and pancreatic cancer have shown that these types of cancer can be resistant or refractory to anti-VEGF signaling therapies [14,16,33,35?7]. Other studie.Contribute to angiogenesis and redirect the role of immune cells. Angiogenesis has long been understood to be an important part of tumorigenesis and many studies have been done to block this process [32]. While important angiogenic factors have been identified such as VEGF, therapeutics against the VEGF signaling pathway have not been proven to be universally successful. Indeed, many cancers are resistant to anti-VEGF therapy or become refractory to administration of these therapies, resulting inPK2/Bv8/PROK2 Antagonist Suppresses TumorigenesisFigure 4. PKRA7 enhances the efficacy of chemotherapeutic drugs 1531364 to reduce glioblastoma and pancreatic xenograft tumor growth. (A) Kaplan-Meier curve of nude mice after temozolomide and PKRA7 treatment following IC injection of 16104 D456MG cells. Treatment with 10 mg/ kg temozolomide or control started 3 days after IC injection for a total of 5 consecutive daily treatments. Treatment with PKRA7 or control started 7 days after IC injection and continued for the duration of experiment. 5 mice per condition. (B) AsPc-1 cells were SC injected into nude mice, and control (n = 10) or PKRA7 (n = 10) treatment was commenced when tumors were visible (7 days). Treatment with 100 mg/kg gemcitabine (n = 10) or control (n = 10) started 7 days after tumor implantation and was administered every 4 days for two weeks for a total of 4 treatments (#). Measurements were taken every 3 days. 5 mice per condition. (C) Average tumor weight of control, gemcitabine, PKRA7 and gemcitabine plus PKRA7-treated mouse tumors after their removal (*p#0.05). doi:10.1371/journal.pone.0054916.grecurrence that is sometimes more aggressive than the primary tumor [14,16,33?8]. There is a need to identify and target additional signaling pathways that may contribute to angiogenesis or other processes that have been shown to be important for tumor progression such as macrophage infiltration. PK2 and its receptors are part of a signaling pathway involved in myeloid cell mobilization [8]. Multiple studies have shown that the CD11b+Gr1+ myeloid precursor cells can contribute to angiogenesis and tumorigenesis in a variety of cancer types [8,37,39]. Macrophages derived from those precursor cells in the tumor microenvironment can also secrete cytokines that directly affect tumor cell growth. In recent studies, the anti-tumor efficacy of an anti-PK2 antibody has been compared to treatment with an anti-VEGF antibody and found to be nearly as effective in preventing disease progression of a transgenic mouse model of pancreatic b-cell tumorigenesis, while the combination of the two antibodies showed an even morepronounced effect in inhibiting subcutaneous growth of different human cancer cell lines (colon cancer, rhabdomyosarcoma) and mouse tumor 24786787 cells (mastocytoma, lymphoma) [8,39]. Anti-PK2 antibody treatment also reduced the number of circulating and tumor-infiltrating CD11b+Gr1+ myeloid cells, including bone marrow-derived macrophages, which have been shown to mediate refractoriness to anti-VEGF therapies in several mouse xenograft tumor models [8,37]. Those studies have indicated PK2 as a legitimate target for cancer therapy. Antibody-based therapies represent a significant portion of cancer treatment options in today’s clinics. However, studies with patients and mouse models of glioblastoma and pancreatic cancer have shown that these types of cancer can be resistant or refractory to anti-VEGF signaling therapies [14,16,33,35?7]. Other studie.
