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Presence of intratumoral platelets is associated with tumor vessel structure and metastasis.

Li R, Ren M, Chen N, Luo M, Deng X, Xia J, Yu G, Liu J, He B, Zhang X, Zhang Z, Zhang X, Ran B, Wu J - BMC Cancer (2014)

Bottom Line: Vascular permeability was evaluated by determination of intratumoral Evans blue and Miles vascular permeability assay.Furthermore, microdialysis was used to examining the intratumoral extracellular angiogenic growth factors (VEGF, TGF-β) by ELISA.Platelet depletion led to reduced tumor hypoxia and Met receptor activation and was associated with a decreased release of MMP-2, 9, PAI-1, VEGF, and TGF-β.

View Article: PubMed Central - HTML - PubMed

Affiliation: Drug Discovery Research Center, Luzhou Medical College, Luzhou, Sichuan, People's Republic of China. wuji@missouri.edu.

ABSTRACT

Background: Platelets play a fundamental role in maintaining hemostasis and have been shown to participate in hematogenous dissemination of tumor cells. Abundant platelets were detected in the tumor microenvironment outside of the blood vessel, thus, platelet -tumor cell interaction outside of the bloodstream may play a role in regulating primary tumor growth and metastasis initiation. However, it is unclear that platelet depletion affects tumor vessel structure and dynamics.

Methods: Using thrombocytopenia induction in two different tumor-bearing mouse models, tumor tissues were performed by Westernblotting and immunohistochemical staining. Vascular permeability was evaluated by determination of intratumoral Evans blue and Miles vascular permeability assay. Furthermore, microdialysis was used to examining the intratumoral extracellular angiogenic growth factors (VEGF, TGF-β) by ELISA.

Results: Platelet depletion showed no change in tumor growth and reduced lung metastasis. Platelet depletion led to reduced tumor hypoxia and Met receptor activation and was associated with a decreased release of MMP-2, 9, PAI-1, VEGF, and TGF-β. Tumor vessels in platelet-depleted mice showed impaired vessel density and maturation.

Conclusions: Our findings demonstrate that platelets within the primary tumor microenvironment play a critical role in the induction of vascular permeability and initiation of tumor metastasis.

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Related in: MedlinePlus

Platelet depletion showed no change in tumor growth but reduced lung metastasis. (A) Orthotopic implantation of B16/F10 tumor cells into C57B6/L mice followed by injections every 3 days of GPI or control antibody after the tumors reached ~500 mm3. (B) Total tumor volumes at the experimental endpoint (24 days). (C) Representative images of H&E-stained lung sections. Scale bar, 5 μm. Arrows point to metastatic areas. Number of metastatic lung nodules in the lungs of these mice. Error bars display mean ± SEM; asterisks denote significance (*p < 0.05). (D) Western blot analysis of p-Met, total Met, and β-actin expression in tumors from control and PLT-depleted mice. Quantification of western blot analysis for total Met (normalized to β-actin) and p-Met (normalized to β-actin), Error bars display mean ± SEM; asterisks denote significance (*p < 0.05) (n = 6 for each group).
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Figure 1: Platelet depletion showed no change in tumor growth but reduced lung metastasis. (A) Orthotopic implantation of B16/F10 tumor cells into C57B6/L mice followed by injections every 3 days of GPI or control antibody after the tumors reached ~500 mm3. (B) Total tumor volumes at the experimental endpoint (24 days). (C) Representative images of H&E-stained lung sections. Scale bar, 5 μm. Arrows point to metastatic areas. Number of metastatic lung nodules in the lungs of these mice. Error bars display mean ± SEM; asterisks denote significance (*p < 0.05). (D) Western blot analysis of p-Met, total Met, and β-actin expression in tumors from control and PLT-depleted mice. Quantification of western blot analysis for total Met (normalized to β-actin) and p-Met (normalized to β-actin), Error bars display mean ± SEM; asterisks denote significance (*p < 0.05) (n = 6 for each group).

Mentions: Previous studies demonstrated that circulating platelets play a shielding role in cancer cell dissemination and hemorrhagic metastasis [1-3]. To evaluate the role of platelets in primary tumor progression and metastasis, we performed thrombocytopenia induction in a tumor-bearing mice model. B16/F10 melanoma cancer cells were implanted into the backs of C57BL/6 J mice. Primary tumor growth was monitored, and when tumors reached ~500 mm3 in size, anti-GPIbα or rat IgG was injected into platelet-depleted or control mice, respectively, every 3 days until 24 days post-injection (Figure 1A). Until the experimental endpoint, platelet-depleted mice showed no change in tumor growth (2777 ± 300 mm3Vs. 2956 ± 180 mm3, p > 0.05) (Figure 1A, B) compared to control mice, while B16/F10 tumor-bearing platelet-depleted mice exhibited a significant reduction in lung metastasis compared to control mice (Figure 1C).


Presence of intratumoral platelets is associated with tumor vessel structure and metastasis.

Li R, Ren M, Chen N, Luo M, Deng X, Xia J, Yu G, Liu J, He B, Zhang X, Zhang Z, Zhang X, Ran B, Wu J - BMC Cancer (2014)

Platelet depletion showed no change in tumor growth but reduced lung metastasis. (A) Orthotopic implantation of B16/F10 tumor cells into C57B6/L mice followed by injections every 3 days of GPI or control antibody after the tumors reached ~500 mm3. (B) Total tumor volumes at the experimental endpoint (24 days). (C) Representative images of H&E-stained lung sections. Scale bar, 5 μm. Arrows point to metastatic areas. Number of metastatic lung nodules in the lungs of these mice. Error bars display mean ± SEM; asterisks denote significance (*p < 0.05). (D) Western blot analysis of p-Met, total Met, and β-actin expression in tumors from control and PLT-depleted mice. Quantification of western blot analysis for total Met (normalized to β-actin) and p-Met (normalized to β-actin), Error bars display mean ± SEM; asterisks denote significance (*p < 0.05) (n = 6 for each group).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4016490&req=5

Figure 1: Platelet depletion showed no change in tumor growth but reduced lung metastasis. (A) Orthotopic implantation of B16/F10 tumor cells into C57B6/L mice followed by injections every 3 days of GPI or control antibody after the tumors reached ~500 mm3. (B) Total tumor volumes at the experimental endpoint (24 days). (C) Representative images of H&E-stained lung sections. Scale bar, 5 μm. Arrows point to metastatic areas. Number of metastatic lung nodules in the lungs of these mice. Error bars display mean ± SEM; asterisks denote significance (*p < 0.05). (D) Western blot analysis of p-Met, total Met, and β-actin expression in tumors from control and PLT-depleted mice. Quantification of western blot analysis for total Met (normalized to β-actin) and p-Met (normalized to β-actin), Error bars display mean ± SEM; asterisks denote significance (*p < 0.05) (n = 6 for each group).
Mentions: Previous studies demonstrated that circulating platelets play a shielding role in cancer cell dissemination and hemorrhagic metastasis [1-3]. To evaluate the role of platelets in primary tumor progression and metastasis, we performed thrombocytopenia induction in a tumor-bearing mice model. B16/F10 melanoma cancer cells were implanted into the backs of C57BL/6 J mice. Primary tumor growth was monitored, and when tumors reached ~500 mm3 in size, anti-GPIbα or rat IgG was injected into platelet-depleted or control mice, respectively, every 3 days until 24 days post-injection (Figure 1A). Until the experimental endpoint, platelet-depleted mice showed no change in tumor growth (2777 ± 300 mm3Vs. 2956 ± 180 mm3, p > 0.05) (Figure 1A, B) compared to control mice, while B16/F10 tumor-bearing platelet-depleted mice exhibited a significant reduction in lung metastasis compared to control mice (Figure 1C).

Bottom Line: Vascular permeability was evaluated by determination of intratumoral Evans blue and Miles vascular permeability assay.Furthermore, microdialysis was used to examining the intratumoral extracellular angiogenic growth factors (VEGF, TGF-β) by ELISA.Platelet depletion led to reduced tumor hypoxia and Met receptor activation and was associated with a decreased release of MMP-2, 9, PAI-1, VEGF, and TGF-β.

View Article: PubMed Central - HTML - PubMed

Affiliation: Drug Discovery Research Center, Luzhou Medical College, Luzhou, Sichuan, People's Republic of China. wuji@missouri.edu.

ABSTRACT

Background: Platelets play a fundamental role in maintaining hemostasis and have been shown to participate in hematogenous dissemination of tumor cells. Abundant platelets were detected in the tumor microenvironment outside of the blood vessel, thus, platelet -tumor cell interaction outside of the bloodstream may play a role in regulating primary tumor growth and metastasis initiation. However, it is unclear that platelet depletion affects tumor vessel structure and dynamics.

Methods: Using thrombocytopenia induction in two different tumor-bearing mouse models, tumor tissues were performed by Westernblotting and immunohistochemical staining. Vascular permeability was evaluated by determination of intratumoral Evans blue and Miles vascular permeability assay. Furthermore, microdialysis was used to examining the intratumoral extracellular angiogenic growth factors (VEGF, TGF-β) by ELISA.

Results: Platelet depletion showed no change in tumor growth and reduced lung metastasis. Platelet depletion led to reduced tumor hypoxia and Met receptor activation and was associated with a decreased release of MMP-2, 9, PAI-1, VEGF, and TGF-β. Tumor vessels in platelet-depleted mice showed impaired vessel density and maturation.

Conclusions: Our findings demonstrate that platelets within the primary tumor microenvironment play a critical role in the induction of vascular permeability and initiation of tumor metastasis.

Show MeSH
Related in: MedlinePlus