Platelet extracts induce growth, migration and invasion in human hepatocellular carcinoma in vitro
© Carr et al.; licensee BioMed Central Ltd. 2014
Received: 13 September 2013
Accepted: 21 January 2014
Published: 27 January 2014
Thrombocytopenia has been reported to be associated with small size HCCs, and thrombocytosis to be associated with large size HCCs. The aim was to examine the effects of platelets in relation to HCC cell growth.
The effects of time-expired pooled normal human platelets were examined on human HCC cell line growth and invasion.
Blood platelet numbers increased with increasing HCC tumor size and portal vein invasion. Platelet extracts enhanced cell growth in 4 human HCC cell lines, as well as cell migration, medium AFP levels and decreased apoptosis. Cell invasion was significantly enhanced, using a Matrigel-coated trans-well membrane and3D (Real-Time Imaging) invasion assay. Western blots showed that platelets caused enhanced phospho-ERK and phospho–JNK signaling and anti-apoptotic effect with increase of Bcl-xL (anti-apoptotic marker) and decrease of Bid (pro-apoptotic marker) levels. Their growth effects were blocked by a JNK inhibitor.
Platelets stimulated growth and invasion of several HCC cell lines in vitro, suggesting that platelets or platelet growth factors could be a potential pharmacological target.
KeywordsPlatelets HCC Growth Migration Invasion AFP
Platelets have a key function in blood clotting. However, it is increasingly recognized that they have other actions, including in cancer biology. Thrombocytosis has been reported to occur in association with solid tumors and over 40% of patients with thrombocytosis without iron deficiency anemia have occult metastasis, typically of the gastrointestinal system, breast, lung and ovary reviews: [1–4]. Cancer can result in altered coagulation and platelet activity and conversely, platelets have the ability to influence cancer growth and metastasis [2, 5]. This can occur by direct platelet effects or through mesenchymal interactions [6, 7].
Platelets have also been reported to enhance liver regenerative growth in animals and hepatocyte proliferation in vitro [8, 9]. Conversely, thrombocytopenia can blunt regeneration . Human hepatocellular carcinoma (HCC) typically arises on the basis of cirrhosis, most commonly caused by hepatitis B or C or alcoholism, exposure to food contamination by mycotoxins or to obesity. The fibrosis that is a key aspect of cirrhosis, eventually causes portal hypertension and associated splenomegaly, that is thought to cause subsequent thrombocytopenia. Thrombocytopenia of cirrhosis has recently been shown to be associated predominantly with small size HCCs , whereas very large size HCCs often have normal platelet counts  and thrombocytosis in HCC patients occurs most often with large size tumors . We have therefore examined the effects of platelet extracts on the growth in vitro of human HCC cell lines and report that they enhance cell proliferation, migration and invasion.
Cells and materials
PLC/PRF/5, Hep3B and HepG2 cells were obtained from the ATCC and were cultured as we previously described .
Apheresis platelets were collected from six healthy blood donors after obtaining their consent and the approval of the Ethics Committee of Institute “Saverio de Bellis” and University of Bari, Italy. The human platelet-rich plasma (PRP) was obtained using an automated haemapheresis procedure in a local blood transfusion center.
The platelets were subjected to several freeze-thaw cycles to disrupt their membranes and release the growth factors stored in the granules (human Platelet Lysate, hPL).
Growth and migration assays
Proliferation and migration assays were performed as recently described . The JNK inhibitor (SP600125; Selleck Chemicals, Houston, TX, USA) 20 μM was used to antagonize cell growth in presence of hPL or FBS.
Medium AFP levels were measured using an automated system (UniCel Integrated Workstations DxC 660i, Beckman Coulter, Fullerton, CA, USA) by a chemioluminescent immunometric method. Sample measurements over the calibration range were automatically re-analyzed according to manufacture’s instructions.
The Muse Annexin V/Dead Cell Assay Kit (Millipore, Darmstadt, Germany) for quantitative analysis of live, early/late apoptotic and dead cells was used with a Muse Cell Analyzer (Millipore). Briefly, the assay utilizes Annexin V to detect PS on the external membrane of apoptotic cells. A dead cell marker (7-AAD) is also used. PLC/PRF/5 cell line, including positive and negative controls, were cultured in 1% FBS medium supplemented with a volume of hPL corresponding to 3.75×107platelets/ml or with an equivalent percentage of serum (control cells) for 48 h. The cells were then processed as described in the user’s guide.
Caspase-3/7 quantitative measurements
The Muse Caspase-3/7 kit (Millipore) permits simultaneous evaluation of apoptotic status based on Caspase-3 and -7 activation and cellular plasma membrane permeabilization (cell death).
The assay provides relative percentage of cells that are live, early/late apoptotic or dead. Cells were cultured as described above and processed according to the user’s guide.
Matrigel invasion assay
Huh7-GFP cells were generated by infection with retroviral particles containing pLXSN-GFP vector (Clontech Laboratories, Mountain View, CA, USA) and isolated by neomycin selection without clonal propagation.
Invasion was performed as previously described . Briefly, 8 μm trans-well membranes (Corning Life Sciences, Manassas, VA, USA) were pre-coated with 20 μg/ml BD Matrigel™ Basement Membrane Matrix (BD Biosciences, Buccinasco (MI), Italy).
Huh7-GFP cells were trypsinized and loaded (1 × 105 cells) into the upper chamber of the trans-well plates and allowed to invade for 24 h. After fixation with 4% paraformaldehyde, invaded cells were quantified by counting the GFP-positive cells.
Real-time imaging of the 3D Matrigel invasion
For 3D experiments, Huh7-GFP were trypsinized, counted and seeded on the top of the lower polymerized Matrigel layer and allowed to adhere and spread. After 3 h, the same cold Matrigel solution was added to cover the cells and to form the upper layer of the 3D Matrigel. Following polymerization, an appropriate dilution of hPL in DMEM medium or DMEM containing 1% BSA was added to the wells. The motility of invasive cells within the 3D Matrigel was monitored by real-time imaging with a modified epi-illumination Zeiss microscope (Zeiss, Oberkochen, Germany) equipped with a Hamamatsu CCD camera (ORCA-AG; Hamamatsu Photonics, Hamamatsu city, Japan). Digital images were acquired using AxioVision imaging software (Zeiss, Jena, Germany) and further processed using Photoshop software (Adobe, San Jose, CA, USA).
We analyzed the MAPK signaling and anti-apoptosis markers in PLC/PRF/5 cells treated with hPL by Western blot, exactly as previously described . In brief, cells were washed twice with cold PBS and then lysed in RIPA buffer (Sigma-Aldrich, Milan; Italy). After quantization of protein concentration, equal amount of protein (50 μg) were resolved on SDS–PAGE and transferred to polyvinyldifluoride (PVDF) filters. The blots were blocked with 5% (w/v) nonfat dry milk for 2 h at room temperature and then probed with primary antibody overnight at 4°C.
The primary antibodies were directed against the following proteins: ERK and phospho-ERK (p-ERK), JNK and phospho-JNK (p-JNK), STAT3 and phospho-STAT3 (Tyr705, Ser727) (pSTAT3), phospho-p38 MAPK (p-p38) and p38 MAPK, AKT and phospho-AKT (p-AKT), Bid, Bcl-xL and β-actin (Cell Signaling, Beverly, MA, USA). Immunoreactive bands were visualized and analyzed usingenhanced chemiluminescence detection reagents (Cell Signaling, Beverly, MA, USA) and a chemiluminescence detection system (ChemiDoc XRS apparatus, Bio-Rad. Milan, Italy). Results were representative of 3 independent experiments.
In vitro experimental data
The differences between two unmatched groups were evaluated by Mann–Whitney nonparametric test.
For multiple comparisons was used one-way Anova test followed by Dunnett's post test.
The computer software used was GraphPad Prism version 5.0.
P-values of <0.05 were considered statistically significant.
All experiments were done in triplicate and data are presented as mean ± standard deviation (mean ± SD).
Platelets as a source of HCC growth stimulants
PLC/PRF/5, HepG2, Hep3B or Huh7-GFP cell lines were cultured in 1% FBS in presence of different hPL concentrations or FBS (control). Cell growth was enhanced by culture with hPL (Figure 1B-E). This growth stimulation was reversible, since sub-culture of the same treated cells without further addition of platelet extracts, resulted in a return to normal pre-treatment growth (data not shown).
Characterization of hPL effects on cell growth
The effects of platelets on cell growth were examined further. Neither red cell (RBCs) nor white cell extracts (WBCs) had similar HCC growth stimulatory effects as platelets (Figure 1F).
Platelet-enhancement of cell invasion
Mechanisms associated with growth stimulation by platelets
The anti-apoptotic effect was associated with two different mechanisms: an increase of Bcl-xL (anti-apoptotic marker) levels and a decrease of Bid (pro-apoptotic marker) levels. To test the significance of the strong p-JNK induction, cell growth enhancement by hPL was repeated in the presence or absence of a JNK inhibitor, which abrogated the stimulatory effects of hPL (Figure 4C).
There have been several studies of the interactions between blood platelets and tumor biology for several human cancers, including ovarian, breast and colon cancer [4, 6, 16, 17]. Several mechanisms have been proposed to be involved, including altered cell adhesion, enhanced coagulation and platelet-derived inflammatory cytokines, angiogenesis factors and and/or tumor growth factors. Thus, platelet changes can occur in conjunction with coagulation changes in response to the growth of tumors, and conversely, platelets may be involved in tumor growth and metastasis [18, 19]. To our knowledge, the current report is a first of a direct effect of platelets on HCC cell growth and invasion. We found that extracts of pooled normal human platelets stimulated growth of several human HCC cell lines in vitro, as well as cell migration and invasion. The effects were time-dependent and reversible, as subsequent sub-culture of platelet-treated cells without platelets, led to loss of the growth stimulant effects. Culture medium AFP levels were also increased with growth stimulation, and low baseline cell apoptosis levels were further reduced by exposure to platelet lysates. The clinical findings of enhanced incidence of portal vein thrombosis in the presence of larger tumors with higher platelet counts, led us to also study cell motility. Cell migration was increased using two different cellular models, an cell invasion was evaluated using Matrigel-treated membranes. The Western blot analysis showed an increase in p-ERK, p-STAT3 and especially p-JNK levels. A JNK inhibitor abrogated the growth stimulatory actions of the platelet extracts, showing the importance of this pathway in the platelet growth enhancing effects. Platelets and platelet-derived growth factors have been previously described to have effects on growth of hepatocytes [8–10, 20–22].
Platelets and their products also influence HCC growth and biology [23–29], but a direct effect has not been previously reported and platelet-inhibition has recently been shown to antagonize hepatocarcinogenesis , likely in this model through modulation of necro-inflammation. Furthermore, experimental chemically induced hepatocarcinogenesis has been reported in association with carcinogen-induced platelet proteome changes . Platelet factors that might be involved in HCC growth include inflammatory cytokines, Vascular endothelial growth factor (VEGF), Fibroblast growth factor (FGF), serotonin and Platelet-derived growth factors (PDGF).
Platelets and their extracts have been recently used therapeutically for their growth enhancing and wound healing effects [32–34], and they contain multiple growth factors including Insulin-like growth factor-1 (IGF-1), Epidermal growth factor (EGF), Transforming growth factor beta (TGFβ), PDGFs, FGFs, VEGFs, serotonin and interleukins. Identification of the platelet factors, which were involved in the growth stimulation reported here, is beyond the scope of this study. These same factors that have therapeutic healing potential for normal cells and tissues, can also worsen tumor growth. This has led to the evaluation of aspirin, a platelet modulator, both for its effects in inhibiting experimental HCC [30, 34–37], but also in clinical trials for cancer risk reduction and metastasis reduction . Platelet modulation has also been reported as affecting metastasis [20, 38, 39], and platelets have been shown to enhance cell migration and invasion [40, 41]. Thus, the modulation of platelet function may have clinical application in both HCC prevention and in improving HCC biology, in patients without thrombocytopenia or other bleeding disorder.
Extracts from normal human platelets, but not from red or white blood cells, could stimulate growth in vitro in several human HCC cell lines. The extracts also stimulated HCC cell migration and invasion. They inhibited apoptosis, by both decreasing apoptotic effectors and inducing anti-apoptotic mediators. p-JNK levels were elevated by hPL actions and JNK was a likely mediator of the hPL growth induction, since the growth increase was antagonized by addition of a JNK inhibitor to the hPL. Platelets therefore represent an additional potential micro-environmental factor in HCC cell growth.
Human Platelets lysates
Portal vein thrombosis
Extracellular signal-regulated kinase
c-Jun NH2-terminal kinase
Signal transducer and activator of transcription-3
We thank Dr MG Giannuzzi of Transfusion Medicine Center, “S. Maria degliAngeli” Hospital (Putignano (BA), Italy), who provided human platelet-rich plasma samples.
This study was supported by NIH grant # CA82723 (BIC) and Italian Ministry of Health.
- Ries I: Zurpathologischen Anatomie des Blutes. Arch Anat Physiol Wissensch Med. 1872, 39: 237-249.Google Scholar
- Leslie M: Cell biology: beyond clotting: the powers of platelets. Science. 2010, 328: 562-564. 10.1126/science.328.5978.562.View ArticlePubMedGoogle Scholar
- Levin J, Conley CL: Thrombocytosis associated with malignant disease. Arch Intern Med. 1964, 114: 497-500. 10.1001/archinte.1964.03860100079008.View ArticlePubMedGoogle Scholar
- Stone RL, Nick AM, McNeish IA, Balkwill F, Han HD, Bottsford-Miller J, Rupairmoole R, Armaiz-Pena GN: Paraneoplastic thrombocytosis in ovarian cancer. N Engl J Med. 2012, 366: 610-618. 10.1056/NEJMoa1110352.View ArticlePubMedPubMed CentralGoogle Scholar
- Borsig L: The role of platelet activation in tumor metastasis. Expert Rev Anticancer Ther. 2008, 8: 1247-1255. 10.1586/1473722.214.171.1247.View ArticlePubMedGoogle Scholar
- Labelle M, Begum S, Hynes RO: Direct signaling between platelets and cancer cells induces an epithelial-mesenchymal-like transition and promotes metastasis. Cancer Cell. 2011, 20: 576-590. 10.1016/j.ccr.2011.09.009.View ArticlePubMedPubMed CentralGoogle Scholar
- Buergy D, Wenz F, Groden C, Brockmann MA: Tumor-platelet interaction in solid tumors. Int J Cancer. 2012, 130: 2747-2760. 10.1002/ijc.27441.View ArticlePubMedGoogle Scholar
- Matsuo R, Nakano Y, Ohkohchi N: Platelet administration via the portal vein promotes liver regeneration in rats after 70% hepatectomy. Ann Surg. 2011, 253: 759-763. 10.1097/SLA.0b013e318211caf8.View ArticlePubMedGoogle Scholar
- Matsuo R, Ohkohchi N, Murata S, Ikeda O, Nakano Y, Watanabe M, Hisakura K, Myronovych A, Kubota T, Narimatsu H, Ozaki M: Platelets strongly induce hepatocyte proliferation with IGF-1and HGF in vitro. J Surg Res. 2008, 145: 279-286. 10.1016/j.jss.2007.02.035.View ArticlePubMedGoogle Scholar
- Lesurtel M, Graf R, Aleil B, Walther DJ, Tian Y, Jochum W, Gachet C, Bader M, Clavien PA: Platelet-derived serotonin mediates liver regeneration. Science. 2006, 312: 104-107. 10.1126/science.1123842.View ArticlePubMedGoogle Scholar
- Carr BI, Guerra V, Pancoska P: Thrombocytopenia in relation to tumor size in patients with hepatocellularcarcinoma. Oncology. 2012, 83: 339-345. 10.1159/000342431.View ArticlePubMedGoogle Scholar
- Carr BI, Guerra V: Features of massive hepatocellular carcinomas. Eur J Gastroenterol Hepatol. 2013, July 16, Epub. PMID 23863262Google Scholar
- Carr BI, Guerra V: Thrombocytosis and hepatocellular carcinoma. Dig Dis Sci. 2013, 58: 1790-1796. 10.1007/s10620-012-2527-3.View ArticlePubMedPubMed CentralGoogle Scholar
- Carr BI, Cavallini A, Lippolis C, D'Alessandro R, Messa C, Refolo MG, Tafaro A: Fluoro-Sorafenib (Regorafenib) effects on hepatoma cells: growth inhibition, quiescence, and recovery. J Cell Physiol. 2013, 228: 292-297. 10.1002/jcp.24148.View ArticlePubMedPubMed CentralGoogle Scholar
- Mazzocca A, Coppari R, De Franco R, Cho JY, Libermann TA, Pinzani M, Toker A: A secreted form of ADAM9 promotes carcinoma invasion through tumor-stromal interactions. Cancer Res. 2005, 65: 4728-4738. 10.1158/0008-5472.CAN-04-4449.View ArticlePubMedGoogle Scholar
- Holmes CE, Levis JE, Ornstein DL: Activated platelets enhance ovarian cancer cell invasion in acellular model of metastasis. Clin Exp Metastasis. 2009, 26: 653-661. 10.1007/s10585-009-9264-9.View ArticlePubMedGoogle Scholar
- Steller EJ, Raats DA, Koster J, Rutten B, Govaert KM, Emmink BL, Snoeren N, van Hooff SR, Holstege FC, Maas C, Borel Rinkes IH, Kranenburg O: PDGFRB promotes liver metastasis Formation of mesenchymal-like colorectal tumor cells. Neoplasia. 2013, 15: 204-207. 10.1593/neo.121726.View ArticlePubMedPubMed CentralGoogle Scholar
- Bambace NM, Holmes CE: The platelet contribution to cancer progression. J Thromb Hemostat. 2011, 9: 237-249. 10.1111/j.1538-7836.2010.04131.x.View ArticleGoogle Scholar
- Goubran HA, Burnouf T, Radosevic M, El-Ekiaby M: The platelet-cancer loop. Eur J Intern Med. 2013, 24: 393-400. 10.1016/j.ejim.2013.01.017.View ArticlePubMedGoogle Scholar
- Kawasaki T, Murata S, Takahashi K, Nozaki R, Ohshiro Y, Ikeda N, Pak S, Myronovych A, Hisakura K, Fukunaga K, Oda T, Sasaki R, Ohkohchi N: Activation of human liver sinusoidal endothelial cell by human platelets induces hepatocyte proliferation. J Hepatol. 2010, 53: 648-654. 10.1016/j.jhep.2010.04.021.View ArticlePubMedGoogle Scholar
- Nowatari T, Fukunaga K, Ohkohchi N: Regulation of signal transduction and role of platelets in liver regeneration. Int J Hepatol. 2012, 2012: 542479-View ArticlePubMedPubMed CentralGoogle Scholar
- Awuah PK, Nejak-Bowen KN, Monga SP: Role and regulation of PDGFRα signaling in liver development and regeneration. Am J Path. 2013, 182: 1648-1658. 10.1016/j.ajpath.2013.01.047.View ArticlePubMedPubMed CentralGoogle Scholar
- Yu Y, Zhou XD, Liu YK, Ren N, Chen J, Zhao Y: Platelets promote the adhesion of human hepatoma cells with a highly metastatic potential to extracellular matrix protein: involvement of platelet P-selectin and GP IIb-IIa. J Cancer Res Clin Oncol. 2000, 128: 283-287.Google Scholar
- Ferroni P, Spila A, D’Alessandro R, Martini F, Iacovone F, Ettorre GM, Vennarecci G, Santoro R, Puoti C, Guadagni F: Platelet activation and vascular endothelial growth factor165 release in hepatocellular carcinoma. Clin Chim Acta. 2011, 412: 450-454. 10.1016/j.cca.2010.11.026.View ArticlePubMedGoogle Scholar
- Zhou J, Tang ZY, Fan J, Wu ZQ, Li XM, Liu YK, Liu F, Sun HC, Ye SL: Expression of platelet-derived endothelial cell growth factor and vascular endothelial cell growth factor in hepatocellular carcinoma and portal vein tumor thrombus. J Cancer Res Clin Oncol. 2000, 126: 57-61. 10.1007/s004320050009.View ArticlePubMedGoogle Scholar
- Yang ZF, Ho DW, Lau CK, Tam KH, Lam CT, Poon RT, Fan ST: Platelet activation during tumor development, the potential roleof BDNF-Trk Bautocrine loop. Biochem Biophys Res Commun. 2006, 346: 981-985. 10.1016/j.bbrc.2006.06.007.View ArticlePubMedGoogle Scholar
- Okada H, Honda M, Campbell JS, Sakai Y, Yamashita T, Takebuchi Y, Hada K, Shirasaki T, Takabatake R, Nakamura M, Sunagozaka H, Tanaka T, Fausto N, Kaneko S: Acyclic retinoid targets platelet-derived growth factor signaling in the prevention of hepatic fibrosis and hepatocellular carcinoma development. Cancer Res. 2012, 72: 4459-4471. 10.1158/0008-5472.CAN-12-0028.View ArticlePubMedGoogle Scholar
- Liang C, Chen W, Zhi X: Serotonin promotes the proliferation of serum-deprived hepatocellularcarcinoma cells via upregulation of FOXO3a. Mol Cancer. 2013, 9: 12-14.Google Scholar
- French DM, Lin BC, Wang M, Adams C, Shek T, Hötzel K, Bolon B, Ferrando R, Blackmore C, Schroeder K, Rodriguez LA, Hristopoulos M, Venook R, Ashkenazi A, Desnoyers LR: Targeting FGFR4 inhibits hepatocellular carcinoma in preclinical mouse models. PLoS One. 2012, 7: e36713-10.1371/journal.pone.0036713.View ArticlePubMedPubMed CentralGoogle Scholar
- Sitia G, Aiolfi R, Di Lucia P, Mainetti M, Fiocchi A, Mingozzi F, Esposito A, Ruggeri ZM, Chisari FV, Iannacone M, Guidotti LG: Antiplatelet therapy prevents hepatocellular carcinoma and improves survival in a mouse model of chronic hepatitis B. Proc Natl Acad Sci USA. 2012, 109: E2165-E2172. 10.1073/pnas.1209182109.View ArticlePubMedPubMed CentralGoogle Scholar
- Leng T, Liu N, Dai Y: Dissection of DEN-induced platelet proteome changes reveals the progressively dys-regulated pathways indicative of hepatocarcinogenesis. J Proteome Res. 2010, 9: 6207-6219. 10.1021/pr100679t.View ArticlePubMedGoogle Scholar
- Amable PR, Carias RB, Teixeira MV, da Cruz Pacheco I, Amaral RJ C d, Granjeiro JM, Borojevic R: Platelet-rich plasma preparation for regenerative medicine: optimization and quantification of cytokines and growth factors. Stem Cell Res Ther. 2013, 4: 67-10.1186/scrt218.View ArticlePubMedPubMed CentralGoogle Scholar
- Dhillon RS, Schwarz EM, Maloney MD: Platelet-rich plasma therapy-future or trend?. Arthritis Res Ther. 2012, 14: 219-10.1186/ar3914.View ArticlePubMedPubMed CentralGoogle Scholar
- Abiru S, Nakao K, Ichikawa T, Migita K, Shigeno M, Sakamoto M, Ishikawa H, Hamasaki K, Nakata K, Eguchi K: Aspirin and NS-398 inhibit hepatocyte growth factor-induced invasiveness of human hepatoma cells. Hepatology. 2002, 35: 1117-1124. 10.1053/jhep.2002.32676.View ArticlePubMedGoogle Scholar
- Hossain MA, Kim DH, Jang JY, Kang YJ, Yoon JH, Moon JO, Chung HY, Kim GY, Choi YH, Copple BL, Kim ND: Aspirin induces apoptosis in vitro and inhibits tumorgrowth of human hepatocellular carcinoma cells in a nude mouse xenograft model. Int J Oncol. 2012, 40: 1298-1304.PubMedGoogle Scholar
- Rothwell PM, Wilson M, Price JF, Belch JF, Meade TW, Mehta Z: Effect of daily aspirin on risk of cancer metastasis: a study of incident cancers during randomised controlled trials. Lancet. 2012, 379: 1591-1601. 10.1016/S0140-6736(12)60209-8.View ArticlePubMedGoogle Scholar
- Algra AM, Rothwell PM: Effects of regular aspirin on long-term cancer incidence and metastasis: a systematic comparison of evidence from observational studies versus randomised trials. Lancet Oncol. 2012, 13: 518-527. 10.1016/S1470-2045(12)70112-2.View ArticlePubMedGoogle Scholar
- Gasic GJ, Gasic TB, Stewart CC: Antimetastatic effects associated with platelet reduction. Proc Natl Acad Sci USA. 1968, 61: 46-52. 10.1073/pnas.61.1.46.View ArticlePubMedPubMed CentralGoogle Scholar
- Futakuchi M, Ogawa K, Sano M, Tamano S, Takeshita F, Shirai T: Suppression of lung metastasis by aspirin but not byindomethacin in an in vivo model of chemically induced hepatocarcinogenesis. Jpn J Cancer Res. 2002, 93: 1175-1181. 10.1111/j.1349-7006.2002.tb01220.x.View ArticlePubMedGoogle Scholar
- Park HB, Yang JH, Chung KH: Characterization of the cytokine profile of platelet rich plasma (PRP) and PRP-induced cell proliferation and migration: upregulation of matrix metalloprotein-1 and -9 in HaCaT cells. Korean J Hematol. 2011, 46: 265-273. 10.5045/kjh.2011.46.4.265.View ArticlePubMedPubMed CentralGoogle Scholar
- Dahesvsky O, Varon D, Brill A: Platelet-derived microparticles promote invasiveness of prostate cancer cells via upregulation of MMP-2 production. Int J Cancer. 2009, 124: 1773-1777. 10.1002/ijc.24016.View ArticleGoogle Scholar
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2407/14/43/prepub
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