Prostaglandin I2 analog suppresses lung metastasis by recruiting pericytes in tumor angiogenesis

  • Authors:
    • Yoshinori Minami
    • Takaaki Sasaki
    • Hiroki Bochimoto
    • Jun‑Ichi Kawabe
    • Satoshi Endo
    • Yoshiki Hira
    • Tsuyoshi Watanabe
    • Shunsuke Okumura
    • Naoyuki Hasebe
    • Yoshinobu Ohsaki
  • View Affiliations

  • Published online on: November 28, 2014     https://doi.org/10.3892/ijo.2014.2783
  • Pages:548-554
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Abstract

Prostaglandin I2 (PGI2) agonist has been reported to reduce tumor metastasis by modifying tumor angiogenesis; however, the mechanisms of how PGI2 affects the endothelial cells or pericytes in tumor vessel maturation are still unclear. The purpose of this study was to clarify the effects of PGI2 on tumor metastasis in a mouse lung metastasis model using Lewis lung carcinoma (LLC) cells. The mice were treated continuously with beraprost sodium (BPS), a PGI2 analog, for 3 weeks and then examined for lung metastases. The number and size of lung metastases were decreased significantly by BPS treatment. In addition, scanning electron microscopy and immunohistochemistry revealed that BPS increased the number of tumor‑associated pericytes and improved intratumor hypoxia. Collectively, this study suggests that BPS attenuated vascular functional maturation in metastatic tumors.

Introduction

Prostaglandin I2 (PGI2) is an important vascular prostanoid that provides an important balance in tumor angiogenesis (1,2). Honn et al were the first to demonstrate that PGI2 strongly reduced the number of lung tumor metastases using an artificial lung metastasis model (3). Since the initial reports of the anti-metastatic action of PGI2 and its analogs, a wide variety of tumor cell lines have been studied in models of artificial metastasis (415). However, the relationship between PGI2-prostacyclin receptor (IP) signaling and tumor angiogenesis, including endothelial cells and pericyte interaction, remains to be clarified.

Tumor blood vessels are structurally and functionally abnormal, in that they lack the normal hierarchical arrangement of arterioles, capillaries, and venules (16). Tumor endothelial cells are often loosely connected to each other and are covered by fewer and more abnormal mural pericytes (1618). In clinical data, low pericyte coverage of tumor blood vessels is related to poor patient prognosis (1921), and pericyte dysfunction is suggested to increase metastasis (22).

Our recent studies have revealed novel effects of PGI2 on its target cells, such as endothelial and endothelial progenitor cells (23), which suggested that PGI2-IP signaling attenuates vascular maturation through endothelial and pericyte interaction. In this study, we evaluated whether activation of PGI2-IP signals of tumor blood vessels by a stable PGI2 analog, beraprost sodium (BPS), enhanced pericyte adhesion to endothelial cells, induced maturation of tumor blood vessels, decreased hypoxic areas in the metastatic tumors, and resulted in suppression of lung metastasis in lung cancer.

Materials and methods

Lung cancer cell line and reagents

Lewis lung carcinoma (LLC; non-small cell lung cancer derived from C57BL/6 mice) cells were purchased from American Type Culture Collection (Manassas, VA, USA) and maintained at 37°C in 5% CO2 using RPMI-1640 medium (Life Technologies, Grand Island, NY, USA) containing 2 mM L-glutamine, 50 U/ml penicillin, and 50 μg/ml streptomycin, supplemented with 10% fetal bovine serum (complete medium). BPS was provided by Toray Industries, Inc. (Chiba, Japan).

Mouse lung metastasis model

Female C57BL/6 mice, 8-.to 10-weeks-old (20–25 g), were obtained from Charles River Laboratories Japan, Inc. (Kanagawa, Japan). LLC cells (5.0×106 cells) in 500 μl phosphate-buffered saline (PBS) were injected into the tail veins of mice (5 mice/group) to generate lung tumor metastases. The day after LLC cell injection, an Alzet mini-osmotic pump (Durect Corp., Cupertino, CA, USA) filled with BPS (20 μg/ml) or deionized distilled water (DDW) was implanted under the skin of each mouse. BPS or DDW was continuously administered for 3 weeks. To assess the hypoxic area in metastatic tumors, mice were orally administered 15 mg/ml Hypoxyprobe-1 (pimonidazole HCl; Hypoxyprobe, Inc., Burlington, MA, USA) 1 h before sacrifice.

Immunohistochemistry

α-SMA (Abcam, Cambridge, UK) and NG2 (Millipore, Billerica, MA, USA) as pericyte markers and Endomucin (Santa Cruz Biotechnology, Inc., Santa Cruz, CA, USA) as an endothelial cell marker were studied by immunofluorescence to evaluate angiogenesis in metastatic lung tumors. Hypoxic areas were evaluated by a Hypoxyprobe-1 kit.

Zinc-fixed lung specimens were sectioned (4 μm thickness), mounted onto slides, and air-dried for 30 min. The sections were deparaffinized in xylene and rehydrated via a series of graded alcohols. The slides were rinsed with PBS, and antigen retrieval was enhanced by microwaving in 10 mM citrate buffer pH 6.0 for 20 min. They were incubated in 1% bovine serum albumin + PBS-T (Triton) for 20 min at room temperature and then incubated overnight at 4°C with a 1:100 dilution of rabbit anti-mouse α-SMA, 1:200 dilution of rabbit anti-mouse NG2, or 1:50 dilution of MAb1 (mouse monoclonal anti-pimonidazole antibody). They were rinsed with PBS and then incubated for 1 h with a goat anti-rabbit Alexa Fluor 488 antibody (diluted 1:1,000) or a donkey anti-mouse Alexa Fluor 488 antibody (diluted 1:1,000) at room temperature. Slides were rinsed with PBS, incubated for 20 min in 1% bovine serum albumin + PBS-T, and then incubated with a 1:50 dilution of rat anti-mouse Endomucin at 4°C overnight. Slides were rinsed with PBS and then incubated for 1 h with a rabbit anti-rat Alexa Fluor 594 antibody (diluted 1:500) at room temperature. After rinsing, slides were incubated with Hoechst 33258 (diluted 1:1,000; Invitrogen Life Technologies, Carlsbad, CA, USA) for 30 min at room temperature. Slides were mounted with Fluoromount (Diagnostic Biosystems, Pleasanton, CA, USA) to prevent fluorescent bleaching.

Quantification of lung metastasis

Excised mouse lungs were fixed in zinc fixative (BD Biosciences Pharmingen, Inc., San Diego, CA, USA) and embedded in paraffin. Tumor metastasis to the lungs was assessed by hematoxylin and eosin (H&E) staining. Light photomicrographs of the left lobe of the lungs were taken at magnification, ×40 (5 visual fields/section and 5 sections/mouse) using a light microscope (BX51; Olympus, Tokyo, Japan). The number of metastatic nodules was counted, and the metastatic area was quantified using ImageJ software (NIH, Bethesda, MD, USA).

DDW- and BPS-treated mice within an experimental set (5 mice/group) were analyzed with the same threshold and results as reported below. Tumors were selected at random from each slide (4 tumors/mouse and 5 mice/group) at magnification, ×200 observed with a fluorescence microscope (BX51; Olympus). The tumor area, number of Endomucin+ cells in the tumor, and number of α-SMA+ (or NG2+)/Endomucin+ double-positive cells in the tumor were quantified. Results were reported as number of vessel-associated pericytes per Endomucin+ cell per tumor area (/mm2). The area of hypoxia was analyzed as described below. Tumors observed with a fluorescence microscope were selected at random from each slide (4 tumors/mouse and 2 mice/group) at original magnification, ×200. The tumor area and area of MAb1+ cells in each tumor were quantified by ImageJ software. The result is reported as the ratio of hypoxic area to tumor area.

Scanning electron microscopy

Tissue preparation for scanning electron microscopy, the potassium hydroxide (KOH) digestion method was described previously (24). Anesthetized control and treated mice were perfused with physiological saline followed by a mixture of 0.5% glutar-aldehyde (GA)-0.5% paraformaldehyde (PFA) in 0.1 M phosphate buffer solution (PB), pH 7.4. After fixation by perfusion, lungs were cut and immersed in 2% GA in 0.1 M PB for 2 weeks at 4°C. Then the tissue blocks were washed thoroughly with 0.1 M PB, immersed in 30% KOH solution for 8–10 min at 60°C to remove the extracellular matrix around tumor blood vessels. After KOH-digested tissue blocks were rinsed five or six times in 0.1 M PB, they were conductively stained by treating with 1% tannic acid in 0.1 M PB (2 h, 20°C) and 1% OsO4 in 0.1 M PB (2 h, 20°C). After conductive staining, the samples were dehydrated in graded ethanols, transferred to isoamyl acetate, and dried in a critical point dryer (HCP-2; Hitachi Koki Co., Ltd., Tokyo, Japan) using liquid CO2. The dried samples were mounted onto a metal plate, coated with platinum-palladium using an ion-sputter coater (E1010; Hitachi Koki Co., Ltd.), and then observed with a field emission type scanning electron microscope (S-4100; Hitachi High-Technologies Corp., Tokyo, Japan).

Clonogenic growth assay

LLC cells (1.5×103 cells) were incubated in 6-well plates for 24 h. Subsequently, growth medium was changed to complete medium containing the indicated concentrations of BPS. Treated cells were incubated under normoxic condition for 10 days. After incubation, colonies in a 6-well plate were stained with 0.5% crystal violet (Wako, Osaka, Japan) in 0.5% methanol. The number of colonies was determined by a colony counter and software (Microtec Nition, Chiba, Japan).

Cell proliferation assay

We used BrdU assays [Cell Proliferation ELISA, BrdU (colorimetric); Roche, Tokyo, Japan] to assess cell proliferation. LLC cells (3.0×103 cells) were incubated in 96-well plates. The next day, the medium was replaced by complete medium containing the indicated concentrations of BPS, and LLC cells were incubated for 3 days. After a 3-day BPS treatment, the BrdU assay was performed according to the manufacturer’s protocol. BrdU was added in the medium, and LLC cells were incubated for 2 h. The BrdU-uptake in the treated cells was assessed using a microplate luminometer (Thermo Fisher Scientific, Waltham, MA, USA).

Antibody array

LLC cells (2.5×103 cells) were incubated in 100 mm dishes for 24 h. Subsequently, the growth medium was changed to complete medium containing 0 or 10 nM BPS. Treated cells were incubated under the normoxic condition for 4 days. After incubation, we measured the cytokine spectrum in the supernatants using the Proteome Profiler™ Mouse Angiogenesis Array kit (R&D Systems, Minneapolis, MN, USA), which detects 53 cytokines, chemokines, and growth factors simultaneously. Array membranes were processed following the manufacturer’s recommendations. The signal intensity was measured on the LAS-3000 luminescence detector, and the resulting images were analyzed using Multi Gauge (Version 2.2; both from Fujifilm, Tokyo, Japan). To compare the luminescence intensities of the samples, we subtracted the background staining and normalized the data to the positive controls on the same membrane.

Statistical analysis

The measurements are presented as means ± SEM. Results were analyzed by Student’s t-test using Microsoft Excel. Two-sided p<0.05 was considered to be statistically significant.

Results

BPS treatment reduces lung metastasis

To evaluate the effect of BPS on lung metastasis, we employed an experimental lung metastasis model. After tumor cell inoculation, mice were treated with BPS for 3 weeks; then they were sacrificed, and lung metastases were counted in the H&E-stained lung sections. In control groups, tumors with wide-spread pleural dissemination of colonized metastases were observed, while tumors with randomly clustered small metastatic nodules were observed in the BPS-treated group (Fig. 1A). The median number of metastatic nodules in the BPS-treated groups was significantly reduced compared with that in the control group (13.8 vs. 21.0, respectively, p<0.05) (Fig. 1B). The median area of metastatic nodules in BPS-treated groups was significantly smaller than that in control groups (0.06 and 0.18/mm2, respectively, p<0.05) (Fig. 1B). These results suggest that administration of BPS significantly reduced the number of lung metastases in our mouse lung metastasis model.

BPS enhances pericyte and endothelial interaction in tumor microvasculature

Next, to evaluate vascular maturation through endothelial and pericyte interaction, we analyzed the structure of tumor blood vessels in the mouse metastatic tumors using scanning electron microscopy. In the BPS-treated group, pericyte bodies (green) attached to endothelial capillary tubes (red) along with processes, and the diameters of tumor blood vessels were decreased, while in the control group, pericytes were absent or loosely connected (Fig. 2A).

To evaluate the effects of BPS on tumor angiogenesis, including pericyte association at the metastatic site, pericytes (α-SMA+ or NG2+ cells) and endothelial cells (Endomucin+ cells) in the metastatic tumor site were analyzed by immunofluorescence (Figs. 2B and 3A). In the control group, α-SMA+ or NG2+ cells were mostly located randomly in the metastatic tumor sites, and they did not colocalize with Endomucin+ cells (Figs. 2B and 3A), while in the BPS-treated group, α-SMA+ or NG2+ cells coexisted regularly beside Endomucin+ cells, and most of these cells were merged with Endomucin+ cells (Figs. 2B and 3A), which revealed that the number of mature pericytes had increased, and moreover, the number of endothelial-attached pericytes was increased compared with that in the control group (Figs. 2C and 3B). These results suggested that BPS strongly enhanced pericyte and endothelial interaction in the tumor microvasculature.

BPS induces vascular functional maturation in metastatic tumors

We hypothesized that functionally mature vasculature without hypoxic regions abrogate tumor metastasis because pericyte-covered endothelial cells are considered ‘mature vasculature,’ which is rarely observed in the tumor area. In order to evaluate the tumor vascular maturation, we measured hypoxia levels in the metastatic tumors by immunohistochemistry using pimonidazole as a hypoxia marker. Pimonidazole stained the inside of the metastatic tumors in the control group widely, while it stained scattered and diminished areas in the BPS-treated group (Fig. 4A). Pimonidazole staining per tumor area in the BPS-treated group was 0.5%, while in the control group it was 1.9%. The area stained by pimonidazole was significantly decreased in the BPS-treated group (p<0.05) (Fig. 4B). These results suggested that BPS induced maturation of vascular function in metastatic tumors.

Antitumor effects of BPS against cancer cells

Because a direct inhibitory effect of a PGI2 analog on tumor cells, has been reported (2527), we evaluated the antitumor effects of BPS on LLC cells. The cell growth was assessed by the BrdU cell growth assay or clonogenic assay (Fig. 5A and B). In our results, BPS did not inhibit tumor growth. To examine the autocrine factors related to tumor angiogenesis, we analyzed the effects of conditioned media with or without BPS on LLC cells using an antibody array that simultaneously detected the relative concentrations of 53 angiogenesis-related proteins (Fig. 5C). In this assay, osteopontin, serpin E1, and MCP-1 were elevated in both BPS-treated and untreated groups, but the change in these factors were not significant. Based on these results, BPS did not affect LLC cell growth directly.

Discussion

In the present study, the number of lung metastases was significantly reduced by BPS treatment in our mouse model. Since the first report from Honn and colleagues demonstrating that PGI2 and its analogs strongly reduced the number of lung metastases (3), studies of the PGI2 effect on metastasis have been repeated using a wide variety of tumor cell lines (415). Because multistep processes of metastasis formation are responsible for the tumor spread, the effect of BPS on tumors and the tumor microenvironment needs to be analyzed. Most studies have examined: i) tumor cell-induced platelet aggregation and its inhibition by PGI2 (5,6,2830); ii) prevention of endothelial cell retraction (3133); iii) modulation of immune systems (4,7); or iii) direct inhibitory effects on tumor cells (2527). However, the mechanisms of tumor vessel maturation by PGI2 was not previously examined.

In this study, we demonstrated that BPS strongly enhanced pericyte and endothelial interaction in the tumor microvasculature, which is a novel anti-metastatic mechanism of a PGI2 analog. The present results suggested that BPS induced structural changes in tumor vessels and led to endothelial maturation, which is consistent with our previous results (34). Consequently, tumor vessel maturation was induced, and hypoxia levels in the metastatic tumors decreased, resulting in BPS-induced vascular normalization in the tumor microenvironment. These results seem paradoxical because improving circulation in the tumor leads to tumor shrinkage, but clinically used anti-angiogenic therapies that successfully target tumor vessels are believed to increase microenvironment-induced tumor shrinkage. Bevacizumab, an anti-angiogenic drug, is now used in combination with cytotoxic agent for vascular normalization.

In the analysis of immunohistochemistry, α-SMA+ cells merged with Endomucin+ cells significantly increased in the BPS-treated group (Fig. 2C), while NG2+ cells merged with Endomucin+ cells did not significantly increase in the BPS-treated group (Fig. 3B). This result seems to be inconsistent. However, in general, it is known that α-SMA expresses in more mature status of pericytes than NG2 (35), and BPS induced more mature pericytes in this study. The number of endothelial cells in the tumors increased in the BPS-treated group with or without pericytes (data not shown). These results indicate that BPS promotes the maturation of tumor blood vessels.

Finally, to rule out the possibility of a direct tumor effect of BPS on LLC cells, we investigated tumor growth inhibition by treatment of cultured cells with BPS at concentrations up to 1 μM. The angiogenic factors produced by LLC cells themselves were not changed. These results suggested that BPS did not affect tumors directly, but affected the tumor microenvironment.

Altering the tumor microenvironment by addition of PGI2 analogs that affect endothelium-pericyte interaction may yield strategies for targeted angiogenesis therapies. However, additional clinical studies are needed to clarify the potential benefits and risks associated with anti-metastatic treatment by PGI2 analogs.

Acknowledgements

The authors thank Dr Fumitaka Ushikubi for advice and kindly providing experimental equipment. This study was partially supported by funding from the JSPS Grant-in-Aid for Scientific Research (C) (KAKENHI) Grant no. 20590910.

References

1 

Turner EC, Mulvaney EP, Reid HM and Kinsella BT: Interaction of the human prostacyclin receptor with the PDZ adapter protein PDZK1: role in endothelial cell migration and angiogenesis. Mol Biol Cell. 22:2664–2679. 2011. View Article : Google Scholar : PubMed/NCBI

2 

Zhu W, Saddar S, Seetharam D, et al: The scavenger receptor class B type I adaptor protein PDZK1 maintains endothelial monolayer integrity. Circ Res. 102:480–487. 2008. View Article : Google Scholar : PubMed/NCBI

3 

Honn KV, Cicone B and Skoff A: Prostacyclin: a potent antimetastatic agent. Science. 212:1270–1272. 1981. View Article : Google Scholar : PubMed/NCBI

4 

Gorelik E, Bere WW and Herberman RB: Role of NK cells in the antimetastatic effect of anticoagulant drugs. Int J Cancer. 33:87–94. 1984. View Article : Google Scholar : PubMed/NCBI

5 

Menter DG, Harkins C, Onoda J, et al: Inhibition of tumor cell induced platelet aggregation by prostacyclin and carbacyclin: an ultrastructural study. Invasion Metastasis. 7:109–128. 1987.PubMed/NCBI

6 

Niitsu Y, Ishigaki S, Kogawa K, et al: Effect of combined administration of a prostacyclin analogue and adriamycin against the artificial metastasis of Meth A cell. Invasion Metastasis. 8:57–72. 1988.PubMed/NCBI

7 

Sava G, Perissin L, Zorzet S, Piccini P and Giraldi T: Antimetastatic action of the prostacyclin analog iloprost in the mouse. Clin Exp Metastasis. 7:671–678. 1989. View Article : Google Scholar : PubMed/NCBI

8 

Honn KV: Inhibition of tumor cell metastasis by modulation of the vascular prostacyclin/thromboxane A2 system. Clin Exp Metastasis. 1:103–114. 1983. View Article : Google Scholar : PubMed/NCBI

9 

Karpatkin S, Ambrogio C and Pearlstein E: Lack of effect of in vivo prostacyclin on the development of pulmonary metastases in mice following intravenous injection of CT26 colon carcinoma, Lewis lung carcinoma, or B16 amelanotic melanoma cells. Cancer Res. 44:3880–3883. 1984.PubMed/NCBI

10 

Mahalingam M, Ugen KE, Kao KJ and Klein PA: Functional role of platelets in experimental metastasis studied with cloned murine fibrosarcoma cell variants. Cancer Res. 48:1460–1464. 1988.PubMed/NCBI

11 

Lapis K, Timár J, Pápay J, Paku S, Szende B and Ladányi A: Experimental metastasis inhibition by pretreatment of the host. Arch Geschwulstforsch. 60:97–102. 1990.PubMed/NCBI

12 

Kato S, Kobari M, Matsuno S and Sato T: Inhibitory effect of anti-platelet prostaglandin on liver metastasis of hamster pancreatic cancer. Nihon Geka Gakkai Zasshi. 90:745–752. 1989.(In Japanese). PubMed/NCBI

13 

Schwalke MA, Tzanakakis GN and Vezeridis MP: Effects of prostacyclin on hepatic metastases from human pancreatic cancer in the nude mouse. J Surg Res. 49:164–167. 1990. View Article : Google Scholar : PubMed/NCBI

14 

Tzanakakis GN, Agarwal KC and Vezeridis MP: Inhibition of hepatic metastasis from a human pancreatic adenocarcinoma (RWP-2) in the nude mouse by prostacyclin, forskolin, and ketoconazole. Cancer. 65:446–451. 1990. View Article : Google Scholar : PubMed/NCBI

15 

Costantini V, Fuschiotti P, Giampietri A, et al: Effects of a stable prostacyclin analogue on platelet activity and on host immunocompetence in mice. Prostaglandins. 39:581–599. 1990. View Article : Google Scholar : PubMed/NCBI

16 

Pasqualini R, Arap W and McDonald DM: Probing the structural and molecular diversity of tumor vasculature. Trends Mol Med. 8:563–571. 2002. View Article : Google Scholar : PubMed/NCBI

17 

Minami Y, Sasaki T, Kawabe J and Ohsaki Y: Accessory cells in tumor angiogenesis - tumor-associated pericytes. Research Directions in Tumor Angiogenesis. Chai J: InTech; Croatia: pp. 73–89. 2013

18 

Morikawa S, Baluk P, Kaidoh T, Haskell A, Jain RK and McDonald DM: Abnormalities in pericytes on blood vessels and endothelial sprouts in tumors. Am J Pathol. 160:985–1000. 2002. View Article : Google Scholar : PubMed/NCBI

19 

O’Keeffe MB, Devlin AH, Burns AJ, et al: Investigation of pericytes, hypoxia, and vascularity in bladder tumors: association with clinical outcomes. Oncol Res. 17:93–101. 2008.

20 

Stefansson IM, Salvesen HB and Akslen LA: Vascular proliferation is important for clinical progress of endometrial cancer. Cancer Res. 66:3303–3309. 2006. View Article : Google Scholar : PubMed/NCBI

21 

Yonenaga Y, Mori A, Onodera H, et al: Absence of smooth muscle actin-positive pericyte coverage of tumor vessels correlates with hematogenous metastasis and prognosis of colorectal cancer patients. Oncology. 69:159–166. 2005. View Article : Google Scholar : PubMed/NCBI

22 

Xian X, Håkansson J, Ståhlberg A, et al: Pericytes limit tumor cell metastasis. J Clin Invest. 116:642–651. 2006. View Article : Google Scholar : PubMed/NCBI

23 

Kawabe J, Yuhki K, Okada M, et al: Prostaglandin I2 promotes recruitment of endothelial progenitor cells and limits vascular remodeling. Arterioscler Thromb Vasc Biol. 30:464–470. 2010. View Article : Google Scholar

24 

Ushiki T and Murakumo M: Scanning electron microscopic studies of tissue elastin components exposed by a KOH-collagenase or simple KOH digestion method. Arch Histol Cytol. 54:427–436. 1991. View Article : Google Scholar : PubMed/NCBI

25 

Tennis MA, Van Scoyk M, Heasley LE, et al: Prostacyclin inhibits non-small cell lung cancer growth by a frizzled 9-dependent pathway that is blocked by secreted frizzled-related protein 1. Neoplasia. 12:244–253. 2010.PubMed/NCBI

26 

Honn KV and Meyer J: Thromboxanes and prostacyclin: positive and negative modulators of tumor growth. Biochem Biophys Res Commun. 102:1122–1129. 1981. View Article : Google Scholar : PubMed/NCBI

27 

Tang DG, Grossi IM, Chen YQ, Diglio CA and Honn KV: 12(S)-HETE promotes tumor-cell adhesion by increasing surface expression of alpha V beta 3 integrins on endothelial cells. Int J Cancer. 54:102–111. 1993. View Article : Google Scholar : PubMed/NCBI

28 

Honn KV, Busse WD and Sloane BF: Prostacyclin and thromboxanes. Implications for their role in tumor cell metastasis. Biochem Pharmacol. 32:1–11. 1983. View Article : Google Scholar : PubMed/NCBI

29 

Menter DG, Onoda JM, Moilanen D, Sloane BF, Taylor JD and Honn KV: Inhibition by prostacyclin of the tumor cell-induced platelet release reaction and platelet aggregation. J Natl Cancer Inst. 78:961–969. 1987.PubMed/NCBI

30 

Menter DG, Onoda JM, Taylor JD and Honn KV: Effects of prostacyclin on tumor cell-induced platelet aggregation. Cancer Res. 44:450–456. 1984.PubMed/NCBI

31 

Honn KV, Tang DG, Grossi IM, et al: Enhanced endothelial cell retraction mediated by 12(S)-HETE: a proposed mechanism for the role of platelets in tumor cell metastasis. Exp Cell Res. 210:1–9. 1994. View Article : Google Scholar : PubMed/NCBI

32 

Honn KV, Grossi IM, Diglio CA, Wojtukiewicz M and Taylor JD: Enhanced tumor cell adhesion to the subendothelial matrix resulting from 12(S)-HETE-induced endothelial cell retraction. FASEB J. 3:2285–2293. 1989.PubMed/NCBI

33 

Honn KV, Tang DG, Grossi I, et al: Tumor cell-derived 12(S)-hydroxyeicosatetraenoic acid induces microvascular endothelial cell retraction. Cancer Res. 54:565–574. 1994.PubMed/NCBI

34 

Aburakawa Y, Kawabe J, Okada M, et al: Prostacyclin stimulated integrin-dependent angiogenic effects of endothelial progenitor cells and mediated potent circulation recovery in ischemic hind limb model. Circ J. 77:1053–1062. 2013. View Article : Google Scholar

35 

Cipriani P, Marrelli A, Benedetto PD, et al: Scleroderma Mesenchymal Stem Cells display a different phenotype from healthy controls; implications for regenerative medicine. Angiogenesis. 16:595–607. 2013. View Article : Google Scholar : PubMed/NCBI

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APA
Minami, Y., Sasaki, T., Bochimoto, H., Kawabe, J., Endo, S., Hira, Y. ... Ohsaki, Y. (2015). Prostaglandin I2 analog suppresses lung metastasis by recruiting pericytes in tumor angiogenesis. International Journal of Oncology, 46, 548-554. https://doi.org/10.3892/ijo.2014.2783
MLA
Minami, Y., Sasaki, T., Bochimoto, H., Kawabe, J., Endo, S., Hira, Y., Watanabe, T., Okumura, S., Hasebe, N., Ohsaki, Y."Prostaglandin I2 analog suppresses lung metastasis by recruiting pericytes in tumor angiogenesis". International Journal of Oncology 46.2 (2015): 548-554.
Chicago
Minami, Y., Sasaki, T., Bochimoto, H., Kawabe, J., Endo, S., Hira, Y., Watanabe, T., Okumura, S., Hasebe, N., Ohsaki, Y."Prostaglandin I2 analog suppresses lung metastasis by recruiting pericytes in tumor angiogenesis". International Journal of Oncology 46, no. 2 (2015): 548-554. https://doi.org/10.3892/ijo.2014.2783