Tanshinone IIA inhibits metastasis after palliative resection of hepatocellular carcinoma and prolongs survival in part via vascular normalization
- Wen-Quan Wang†1, 2,
- Liang Liu†2,
- Hui-Chuan Sun†1,
- Yan-Ling Fu3,
- Hua-Xiang Xu2,
- Zong-Tao Chai1,
- Qiang-Bo Zhang1,
- Ling-Qun Kong1,
- Xiao-Dong Zhu1,
- Lu Lu1,
- Zheng-Gang Ren1 and
- Zhao-You Tang1Email author
© Wang et al.; licensee BioMed Central Ltd. 2012
Received: 8 October 2012
Accepted: 16 October 2012
Published: 8 November 2012
Promotion of endothelial normalization restores tumor oxygenation and obstructs tumor cells invasion, intravasation, and metastasis. We therefore investigated whether a vasoactive drug, tanshinone IIA, could inhibit metastasis by inducing vascular normalization after palliative resection (PR) of hepatocellular carcinoma (HCC).
A liver orthotopic double-tumor xenograft model in nude mouse was established by implantation of HCCLM3 (high metastatic potential) and HepG2 tumor cells. After removal of one tumor by PR, the effects of tanshinone IIA administration on metastasis, tumor vascularization, and survival were evaluated. Tube formation was examined in mouse tumor-derived endothelial cells (TECs) treated with tanshinone IIA.
PR significantly accelerated residual hepatoma metastases. Tanshinone IIA did not inhibit growth of single-xenotransplanted tumors, but it did reduce the occurrence of metastases. Moreover, it inhibited PR-enhanced metastases and, more importantly, prolonged host survival. Tanshinone IIA alleviated residual tumor hypoxia and suppressed epithelial-mesenchymal transition (EMT) in vivo; however, it did not downregulate hypoxia-inducible factor 1α (HIF-1α) or reverse EMT of tumor cells under hypoxic conditions in vitro. Tanshinone IIA directly strengthened tube formation of TECs, associated with vascular endothelial cell growth factor receptor 1/platelet derived growth factor receptor (VEGFR1/PDGFR) upregulation. Although the microvessel density (MVD) of residual tumor tissue increased after PR, the microvessel integrity (MVI) was still low. While tanshinone IIA did not inhibit MVD, it did dramatically increase MVI, leading to vascular normalization.
Our results demonstrate that tanshinone IIA can inhibit the enhanced HCC metastasis associated with PR. Inhibition results from promoting VEGFR1/PDGFR-related vascular normalization. This application demonstrates the potential clinical benefit of preventing postsurgical recurrence.
KeywordsTanshinone IIA Vascular normalization Palliative resection Hepatocellular carcinoma Metastasis
Surgical resection is the most promising strategy for early-stage hepatocellular carcinoma (HCC); however, the 5-year risk of recurrence is as high as 70% . The surgery is actually palliative resection (PR), owing to the existence of satellites and microvascular invasion, and these residual tumor nests can actually be stimulated to grow by the PR [2, 3]. Although several treatments, such as interferon-alpha and sorafenib, have been proposed to diminish relapse [4, 5], prometastatic side effects of these options have also been observed [6, 7].
Residual tumor cells may stimulate angiogenesis, which is needed for tumor growth [8–10]. However, the resulting neovessels may be disordered and inefficiently perfused, resulting in hypoxic conditions [10, 11]. Both abnormal endothelium and pericytes integrated into the capillary wall, along with deficient coverage, could be responsible for the vascular architectural abnormalities . The resulting hypoxia creates a hostile tumor milieu in which tumor cells may migrate via intra- or extravasation through a leaky vessel [9, 13]. In effect, surgery-induced hypoxia unfavorably impacts the prognosis of cancer patients by inducing angiogenesis . Therefore, restoring oxygen supply via vascular normalization may reduce metastasis, even tumor growth. Mazzone et al.  showed that downregulation of the oxygen sensing molecule PHD2 can restore tumor oxygenation and inhibit metastasis via endothelial normalization, where endothelial cells form a protective phalanx that blocks metastasis. Although several methods have been shown experimentally to promote vessel remodeling, only seldom has any of them found use in the clinic [9, 10, 15, 16].
Tanshinone IIA (Tan IIA) is an herbal monomer with a clear chemical structure, isolated from Salvia miltiorrhiza. In Chinese traditional medicine, S. miltiorrhiza is considered to promote blood circulation for removing blood stasis and improve microcirculation. Some of these effects could include vessel normalization. We have reported that an herbal formula, Songyou Yin, can attenuate HCC metastases , and S. miltiorrhiza is one of the five constituents of the formula . Tan IIA exhibits direct vasoactive [19, 20] and certain antitumor properties . It is possible that Tan IIA may indirectly decrease metastasis in HCC following PR by promoting blood vessel normalization; however, there is to date no evidence supporting this hypothesis.
We aimed to identify inhibitory effects of Tan IIA on HCC metastasis for delineating a possible mechanism of action of the compound, with a main focus on tumor vessel maturity as a potential marker for evaluating Tan IIA treatment responses.
PR-induced residual tumor growth and metastasis
Summary of tumor growth, metastasis, and mice’s survival from three animal experiments of HCCLM3
Tan IIA 1
Tan IIA 5
Tan IIA 10
PR+Tan IIA 10
Tan IIA does not directly inhibit tumor growth but reduces metastasis
Results of IE (2), shown in Tables 1 and Additional file 1: Table S2, indicate there were no differences in TV between the four groups observed (Additional file 1: Figure S1A). Compared with normal saline (NS), the LM of the Tan IIA-treated groups (5 or 10 mg/kg/d) decreased (p=0.046 and p<0.001, Additional file 1: Figure S1B). Compared with Tan IIA treatment of 1 or 5 mg/kg/d, the LM of the 10 mg/kg/d group also decreased (p=0.003 and p=0.046, Additional file 1: Figure S1B). Both the IHM and AM rates of the 5/10 mg Tan IIA/kg/d treatment groups were significantly reduced (p<0.05, Additional file 1: Figure S1C and D). No AM deriving from HepG2 cells was found. The greatest inhibitory effects were seen at a dosage of 10 mg/kg/d, which was chosen as the intervention dosage in IE (3).
Tan IIA inhibits the PR-enhanced residual tumor metastasis
Results of IE (3), summarized in Tables 1 and Additional file 1: Table S2, show that administration of Tan IIA after PR resulted in decreased residual TV compared to NS (p<0.05, Additional file 1: Figure S1A). Compared with the PR + NS group, the LM (HCCLM3) of the Tan IIA treatment group was significantly decreased (p<0.001, Figures 1A and Additional file 1: Figure S1B); both IHM and AM also decreased (p<0.01 for IHM, Figures 1B, Additional file 1: Figure S1C, and S2A; p<0.01 for AM, Figures 1C, Additional file 1: Figure S1D, and S2B), and the CTCs were relatively decreased (p<0.001, Additional file 1: Figure S1E).
Tan IIA prolongs host survival
Tan IIA treatment retarded the weight loss of mice after PR (Additional file 1: Figure S3). The estimated survival of PR mice was significantly shorter than of Sham mice in IE (1) (p<0.01, Tables 1 and Additional file 1: Table S2, Figure 1D). In IE (2), Tan IIA prolonged the mice’s survival up to 16 d for HCCLM3 (87.000 ± 3.804 vs. 102.667 ± 3.201, p=0.004) and 19 d for HepG2 (p<0.001, Tables 1 and Additional file 1: Table S2, Figure 1D), compared with NS. The same effect on prolongation of post-PR survival was seen in IE (3) (p=0.001 for both, Tables 1 and Additional file 1: Table S2, Figure 1D).
Tan IIA does not inhibit proliferation but minimizes invasiveness of tumor cells
Tan IIA alleviates residual tumor hypoxia in vivo but does not downregulate HIF-1 of tumor cells under hypoxic conditions in vitro
Tan IIA does not affect microvessel density but promotes microvessel integrity
Tan IIA enhances tube formation and is associated with vascular endothelial cell growth factor receptor 1 (VEGFR1) and platelet derived growth factor receptor (PDGFR) upregulation
In the present study of postsurgical residual tumors, we established a double-tumor xenograft HCC model and found that PR accelerated local aggressivity and distant metastasis. Administration of Tan IIA after PR significantly inhibited metastases and prolonged survival of nude mice bearing residual tumor tissue, and the effect was closely associated with VEGFR1/PDGFR-related vascular normalization.
Early in 1959, Fisher et al.  found that partial hepatectomy elicited hepatic metastases. Our results confirm the view that incomplete surgical resection of primary tumor may well induce the metastatic potential of residual tumor tissue. Currently, there is no evidence indicating that presurgical primary tumor could govern postsurgical residual tumor when growing in the same liver lobe. Interestingly, we found that residual tumor hypoxia was aggravated, HIF-1α was upregulated, and EMT was induced after surgical removal of “primary tumor.” Van der Bilt et al.  have reported that surgery-induced tumor hypoxia can stimulate abnormal angiogenesis. Our findings that neovascular abnormality is significantly augmented following PR are consistent with that report. Severe tumor hypoxia might have effects on abnormalities in the vasculature by promoting release of angiogenic cytokines , which would enhance metastasis.
Tumor vessel abnormalities could promote metastasis through mechanical penetration and hypoxia-induced EMT. We selected Tan IIA, known to possess potential vascular activity, to investigate inhibition of metastasis and the association with vascular normalization. We observed that Tan IIA could inhibit post-PR enhanced metastases and, more importantly, prolong survival. At a cellular level, Tan IIA showed no effect on tumor cell proliferation, but it minimized invasion. These effects were consistent with in vivo results showing that Tan IIA did not inhibit single-xenograft tumor growth but decreased metastases. A possible mechanism may be related by correlation with the observed E-cadherin upregulation. Furthermore, we observed that Tan IIA significantly alleviates residual tumor hypoxia and inhibits EMT in vivo. However, it did not downregulate HIF-1α or reverse EMT of tumor cells under hypoxic conditions in vitro. Therefore, we propose that the main inhibition of metastasis by Tan IIA is indirect.
We also observed that the tumor MVD increased after PR, but the MVI was low, suggesting that the surgery-induced angiogenesis was related to structural abnormalities . Tumor cells would metastasize more easily through such a leaky vascular wall, causing an increase of CTCs. Tan IIA did not inhibit MVD but dramatically improved MVI, which is probably related to its underlying vasoactivity. Tan IIA also enhanced tube formation of endothelial cells under hypoxic conditions in vitro. Additionally, we found that tube formation of mouse TECs which processed with Tan IIA no matter in vivo or in vitro, was similar to each other, further indicating a direct effect of Tan IIA on endothelium. How Tan IIA may promote vascular normalization is not entirely clear because its receptor on endothelial cells is unknown. Our results have shown a possible correlation with VEGFR1 and PDGFR upregulation. Recently, it has been reported that inhibition of VEGFR1 and PDGFR signaling in several tumors causes pericyte detachment and vessel regression, leading to vascular abnormalities [23, 24]. This implies that upregulation of this signaling might produce a beneficial effect. Of relevance is the observation that a compound AZD2171 inhibits VEGFR while promoting vessel normalization . The mechanism of Tan IIA action requires further investigation.
Vascular normalization has effects on two major processes: (i) mechanical prevention of tumor cell migration via intra/extravasation; and (ii) restoration of oxygen and nutritional supply. However, recovery of tumor blood supply may have mixed effects by contributing to progression while also suppressing tumor growth . The latter effect is likely to depend on a combination of factors. The normalization of vessels from both direct and indirect Tan IIA effects appears to be involved with inhibition of residual tumor growth, invasion, and metastasis.
Our findings demonstrate that Tan IIA can inhibit the enhanced metastasis induced by PR and may do so in part via VEGFR1/PDGFR-related vascular normalization. This work has an important implication: that the malignant phenotype of a tumor may be manipulated through vascular pathways, which could be an alternative to simple eradication. Our results highlight the potential of proangiogenic “vessel normalizing” treatment strategies to silence metastasis and prolong patient survival.
Cell lines, animal model, and drug
The human HCC cell lines HCCLM3-RFP, which has high metastatic potential , and HepG2-GFP , HUVECs, and TECs  were used in the studies. Male, athymic BALB/c nu/nu mice of 4–6 weeks of age and weighing approximately 20 g were used as host animals.
A metastatic human HCC animal model was established by orthotopic implantation of histologically intact tumor tissue into the nude mouse liver . To explore the protumoral effects of PR, we constructed an orthotopic double-tumor xenograft model, in which two tumor pieces were simultaneously inoculated into the left liver lobe; the inoculation method was as described . After 2 weeks, partial hepatectomy  was performed to excise one tumor. The Sham hepatectomy cohort was handled like the PR cohort, but without tumor resection.
Tan IIA (sulfotanshinone sodium injection, 5 mg/ml), commercially available from the first Biochemical Pharmaceutical Co. Ltd., Shanghai, China, was used in in vivo experiment. Tan IIA monomer (Sigma, St. Louis, MO), a reddish lyophilized powder with the purity 99.99%, firstly dissolved in dimethyl sulfoxide and then diluted with NS to the required concentration, was used in in vitro study.
Experimental groups and assessment parameters
For IE (1), 30 double-tumor-bearing mice were randomly divided into Sham and PR groups (each of n=15) and scheduled to be observed after 35 d. In IE (2), the single-tumor xenograft model was used. Mice were divided into four groups (each n=18) and received daily injections of NS or Tan IIA (1, 5, or 10 mg/kg/d). Tan IIA was diluted with NS. We took 20 g as the average mouse weight (25 g after 21 d), and each mouse received 0.2 mL solution intraperitoneally for 35 d. In IE (3), the double-tumor xenograft plus PR model was used to examine effects of Tan IIA on residual tumor. Mice were divided into two groups (each n=15) after PR and received daily injections of NS or 10 mg Tan IIA/kg/d for 35 d.
The mouse weight was measured once every 7 d. After 35 d, six mice from each group were retained to observe survival, and the remaining were sacrificed to measure TV , LM, IHM, AM , CTCs, and to perform SEM of tumor vessels. CTCs were enumerated by flow cytometry and expressed as percent CTCs/TV (%) . Twelve mice (IE 1, n = 6) were sacrificed 2 d after resection to examine CTCs shortly after PR.
Cell proliferation and invasion
A Cell Counting Kit-8 (Dojindo, Kumamoto, Japan) was used to assay cell proliferation. The final concentration of Tan IIA was 0.01–1000 μM. Results were expressed as OD at 490 nm. Cell invasiveness was assayed in Matrigel-coated Transwell Invasion Chambers (Corning, Cambridge, MA). Tan IIA was added to cells at final concentrations of 1, 5, or 10 μM, and these cultures were incubated for 48 h. Cells that passed through the chamber membranes were counted.
Cells were cultured in a Bugbox Hypoxic Workstation (Ruskinn, Mid Glamorgan, UK; 1% O2, 5% CO2, and 94% N2 atmosphere) and incubated with Tan IIA at 1, 5, or 10 μM for 48 h. Normoxic conditions (20% O2, 5% CO2, and 75% N2) were set as control. Pimonidazole immunostaining and HIF-1α expression were defined as hypoxia biomarkers. A Hypoxyprobe™-1 Kit (Hypoxyprobe Inc., Burlington, MA) was used .
Isolation of TECs, flow cytometry, and tube formation
Eight tumors from Sham, PR, or PR + Tan IIA groups were collected. The TECs were isolated by use of anti-CD31 antibody (AB)-coupled magnetic beads (Miltenyi Biotec, Cologne, Germany) and magnetic cell-sorting system , and they were divided into Sham, PR, PR + Tan IIA (in vivo), and PR + Tan IIA (in vitro) groups; TECs isolated from the PR group were incubated with Tan IIA for 48 h. TEC surface expression of VEGFR1, VEGFR2, EGFR, PDGFR, FGFR1, and CD31 was determined by flow cytometric analysis (R&D, Minneapolis, MN). Receptor density was calculated as the relative fluorescence intensity. In another set of experiments, TECs from the PR + Tan IIA (in vivo) cohort were divided into control and SU6668 (Sigma) (VEGFR1/PDGFR selective receptor inhibitor) treatment groups. TECs from the PR cohort were also divided into PR, PR + SU6668, PR + Tan IIA (in vitro), and PR + SU6668 + Tan IIA groups. HUVECs and human TECs were separated into control, normoxia + Tan IIA, and hypoxia + Tan IIA groups. Formation of capillary-like structures was observed as described .
Immunohistochemistry, immunofluorescence, western blot, and quantitative real-time polymerase chain reaction
Immunohistochemistry  of Pimonidazole, CD31, and NG2  was performed in paraffin sections on slides. The primary antibodies to Pimonidazole (1:100), CD31 (1:100; Abcam, Cambridge, MA), and NG2 (1:200; Millipore, Billerica, MA) were selected. The integrated optical density (IOD; for Pimonidazole) or area (for CD31 and NG2) of positive staining/total area was quantified by Image-Pro Plus software . IF double-staining  of CD31 (1:50) and NG2 (1:50), and NG2 and Pimonidazole (1:80) was done in frozen sections and observed under laser confocal microscope. IF of E-cadherin in cells was also determined.
Protein levels of HIF-1α, N-cadherin, E-cadherin, and vimentin were determined by immunoblot analysis. Primary antibodies against HIF-1α (1:1000; Sigma), β-actin, N-cadherin (1:1000; Abcam), E-cadherin (1:400; Santa Cruz Biotechnology, Santa Cruz, CA), and vimentin (1:800; Cell Signaling Technology, Beverly, MA) were used. Levels of mRNA were assessed by polymerase chain reaction (Additional file 1: Table S1) and normalized to the corresponding internal β-actin signal (ΔCt). Relative gene expression values were expressed as 2−ΔΔCt.
All statistical analyses were performed with the SPSS 16.0 software. The Pearson chi-square test was applied to compare qualitative variables. Quantitative variables were expressed as mean ± standard deviations and analyzed by t-test or one-way analysis of variance followed by least significant difference test. The Kaplan–Meier method with log-rank test was used for survival analysis. A p value of <0.05 was considered to be statistically significant.
Animal care and experimental protocols were approved by the Shanghai Medical Experimental Animal Care Commission.
WWQ, M.D., Ph.D., in Cancer Surgery. Graduated from Liver Cancer Institute, Zhongshan Hospital, Fudan University; Key Laboratory for Carcinogenesis & Cancer Invasion (Fudan University), the Chinese Ministry of Education. WWQ is now working in the Department of Pancreatic and Hepatobiliary Surgery, Fudan University, Shanghai Cancer Center; the Department of Oncology, Shanghai Medical College, Fudan University; and the Pancreatic Cancer Institute, Fudan University.
Circulating tumor cells
Human umbilical vein endothelial cells
In vivo experiment
Integrated optical density
Platelet derived growth factor receptor
Scanning electron microscopy
- Tan IIA:
Tumor-derived endothelial cells
Vascular endothelial cell growth factor receptor 1.
The authors thank Dr. Dong-Li Song (Biomedical Research Center, Zhongshan Hospital, Fudan University, Shanghai, China) for technical support in studies of circulating tumor cells. This study was jointly supported by the Postgraduate Innovation Fund sponsored by Fudan University (EHF152201), the National Key Science and Technology Specific Project (2008ZX10002-019,021), and the National Natural Science Foundation of China (No. 81172005).
- El-Serag HB: Hepatocellular carcinoma. N Engl J Med. 2011, 365: 1118-1127. 10.1056/NEJMra1001683.View ArticlePubMedGoogle Scholar
- Meredith K, Haemmerich D, Qi C, Mahvi D: Hepatic resection but not radiofrequency ablation results in tumor growth and increased growth factor expression. Ann Surg. 2007, 245: 771-776. 10.1097/01.sla.0000261319.51744.59.PubMed CentralView ArticlePubMedGoogle Scholar
- Takemoto Y, Li TS, Kubo M, Ohshima M, Ueda K, Harada E, Enoki T, Okamoto M, Mizukami Y, Murata T, Hamano K: Operative injury accelerates tumor growth by inducing mobilization and recruitment of bone marrow-derived stem cells. Surgery. 2011, 149: 792-800. 10.1016/j.surg.2011.02.005.View ArticlePubMedGoogle Scholar
- Wang L, Tang ZY, Qin LX, Wu XF, Sun HC, Xue Q, Ye SL: High-dose and long-term therapy with interferon-alfa inhibits tumor growth and recurrence in nude mice bearing human hepatocellular carcinoma xenografts with high metastatic potential. Hepatology. 2000, 32: 43-48.View ArticlePubMedGoogle Scholar
- Feng YX, Wang T, Deng YZ, Yang P, Li JJ, Guan DX, Yao F, Zhu YQ, Qin Y, Wang H: Sorafenib suppresses postsurgical recurrence and metastasis of hepatocellular carcinoma in an orthotopic mouse model. Hepatology. 2011, 53: 483-492. 10.1002/hep.24075.View ArticlePubMedGoogle Scholar
- Zhuang PY, Zhang JB, Zhang W, Zhu XD, Liang Y, Xu HX, Xiong YQ, Kong LQ, Wang L, Wu WZ: Long-term interferon-alpha treatment suppresses tumor growth but promotes metastasis capacity in hepatocellular carcinoma. J Cancer Res Clin Oncol. 2010, 136: 1891-1900. 10.1007/s00432-010-0848-1.View ArticlePubMedGoogle Scholar
- Ebos JM, Lee CR, Cruz-Munoz W, Bjarnason GA, Christensen JG, Kerbel RS: Accelerated metastasis after short-term treatment with a potent inhibitor of tumor angiogenesis. Cancer Cell. 2009, 15: 232-239. 10.1016/j.ccr.2009.01.021.PubMed CentralView ArticlePubMedGoogle Scholar
- Al-Sahaf O, Wang JH, Browne TJ, Cotter TG, Redmond HP: Surgical injury enhances the expression of genes that mediate breast cancer metastasis to the lung. Ann Surg. 2010, 252: 1037-1043. 10.1097/SLA.0b013e3181efc635.View ArticlePubMedGoogle Scholar
- Rolny C, Mazzone M, Tugues S, Laoui D, Johansson I, Coulon C, Squadrito ML, Segura I, Li X, Knevels E: HRG inhibits tumor growth and metastasis by inducing macrophage polarization and vessel normalization through downregulation of PlGF. Cancer Cell. 2011, 19: 31-44. 10.1016/j.ccr.2010.11.009.View ArticlePubMedGoogle Scholar
- Jain RK: Normalization of tumor vasculature: an emerging concept in antiangiogenic therapy. Science. 2005, 307: 58-62. 10.1126/science.1104819.View ArticlePubMedGoogle Scholar
- Goel S, Duda DG, Xu L, Munn LL, Boucher Y, Fukumura D, Jain RK: Normalization of the vasculature for treatment of cancer and other diseases. Physiol Rev. 2011, 91: 1071-1121. 10.1152/physrev.00038.2010.PubMed CentralView ArticlePubMedGoogle Scholar
- Raza A, Franklin MJ, Dudek AZ: Pericytes and vessel maturation during tumor angiogenesis and metastasis. Am J Hematol. 2010, 85: 593-598. 10.1002/ajh.21745.View ArticlePubMedGoogle Scholar
- Mazzone M, Dettori D, Leite De Oliveira R, Loges S, Schmidt T, Jonckx B, Tian YM, Lanahan AA, Pollard P, Ruiz De Almodovar C: Heterozygous deficiency of PHD2 restores tumor oxygenation and inhibits metastasis via endothelial normalization. Cell. 2009, 136: 839-851. 10.1016/j.cell.2009.01.020.PubMed CentralView ArticlePubMedGoogle Scholar
- van der Bilt JD, Borel Rinkes IH: Surgery and angiogenesis. Biochim Biophys Acta. 2004, 1654: 95-104.PubMedGoogle Scholar
- Sasajima J, Mizukami Y, Sugiyama Y, Nakamura K, Kawamoto T, Koizumi K, Fujii R, Motomura W, Sato K, Suzuki Y: Transplanting normal vascular proangiogenic cells to tumor-bearing mice triggers vascular remodeling and reduces hypoxia in tumors. Cancer Res. 2010, 70: 6283-6292. 10.1158/0008-5472.CAN-10-0412.PubMed CentralView ArticlePubMedGoogle Scholar
- Batchelor TT, Sorensen AG, di Tomaso E, Zhang WT, Duda DG, Cohen KS, Kozak KR, Cahill DP, Chen PJ, Zhu M: AZD2171, a pan-VEGF receptor tyrosine kinase inhibitor, normalizes tumor vasculature and alleviates edema in glioblastoma patients. Cancer Cell. 2007, 11: 83-95. 10.1016/j.ccr.2006.11.021.PubMed CentralView ArticlePubMedGoogle Scholar
- Huang XY, Huang ZL, Wang L, Xu YH, Ai KX, Zheng Q, Tang ZY: Herbal compound "Songyou Yin" reinforced the ability of interferon-alfa to inhibit the enhanced metastatic potential induced by palliative resection of hepatocellular carcinoma in nude mice. BMC Cancer. 2010, 10: 580-10.1186/1471-2407-10-580.PubMed CentralView ArticlePubMedGoogle Scholar
- Huang XY, Wang L, Huang ZL, Zheng Q, Li QS, Tang ZY: Herbal extract "Songyou Yin" inhibits tumor growth and prolongs survival in nude mice bearing human hepatocellular carcinoma xenograft with high metastatic potential. J Cancer Res Clin Oncol. 2009, 135: 1245-1255. 10.1007/s00432-009-0566-8.View ArticlePubMedGoogle Scholar
- Wang J, Dong MQ, Liu ML, Xu DQ, Luo Y, Zhang B, Liu LL, Xu M, Zhao PT, Gao YQ, Li ZC: Tanshinone IIA modulates pulmonary vascular response to agonist and hypoxia primarily via inhibiting Ca2+ influx and release in normal and hypoxic pulmonary hypertension rats. Eur J Pharmacol. 2010, 640: 129-138. 10.1016/j.ejphar.2010.04.047.View ArticlePubMedGoogle Scholar
- Fan G, Zhu Y, Guo H, Wang X, Wang H, Gao X: Direct vasorelaxation by a novel phytoestrogen tanshinone IIA is mediated by nongenomic action of estrogen receptor through endothelial nitric oxide synthase activation and calcium mobilization. J Cardiovasc Pharmacol. 2011, 57: 340-347. 10.1097/FJC.0b013e31820a0da1.View ArticlePubMedGoogle Scholar
- Wang L, Zhou GB, Liu P, Song JH, Liang Y, Yan XJ, Xu F, Wang BS, Mao JH, Shen ZX: Dissection of mechanisms of Chinese medicinal formula Realgar-Indigo naturalis as an effective treatment for promyelocytic leukemia. Proc Natl Acad Sci U S A. 2008, 105: 4826-4831. 10.1073/pnas.0712365105.PubMed CentralView ArticlePubMedGoogle Scholar
- Fisher B, Fisher ER: Experimental studies of factors influencing hepatic metastases, III. Effect of surgical trauma with special reference to liver injury. Ann Surg. 1959, 150: 731-744. 10.1097/00000658-195910000-00015.PubMed CentralView ArticlePubMedGoogle Scholar
- Bergers G, Song S, Meyer-Morse N, Bergsland E, Hanahan D: Benefits of targeting both pericytes and endothelial cells in the tumor vasculature with kinase inhibitors. J Clin Invest. 2003, 111: 1287-1295.PubMed CentralView ArticlePubMedGoogle Scholar
- Erber R, Thurnher A, Katsen AD, Groth G, Kerger H, Hammes HP, Menger MD, Ullrich A, Vajkoczy P: Combined inhibition of VEGF and PDGF signaling enforces tumor vessel regression by interfering with pericyte-mediated endothelial cell survival mechanisms. FASEB J. 2004, 18: 338-340.PubMedGoogle Scholar
- Li Y, Tang ZY, Hou JX: Hepatocellular carcinoma: insight from animal models. Nat Rev Gastroenterol Hepatol. 2011, 9: 32-43. 10.1038/nrgastro.2011.196.View ArticlePubMedGoogle Scholar
- Yang BW, Liang Y, Xia JL, Sun HC, Wang L, Zhang JB, Tang ZY, Liu KD, Chen J, Xue Q: Biological characteristics of fluorescent protein-expressing human hepatocellular carcinoma xenograft model in nude mice. Eur J Gastroenterol Hepatol. 2008, 20: 1077-1084. 10.1097/MEG.0b013e3283050a67.View ArticlePubMedGoogle Scholar
- Xiong YQ, Sun HC, Zhang W, Zhu XD, Zhuang PY, Zhang JB, Wang L, Wu WZ, Qin LX, Tang ZY: Human hepatocellular carcinoma tumor-derived endothelial cells manifest increased angiogenesis capability and drug resistance compared with normal endothelial cells. Clin Cancer Res. 2009, 15: 4838-4846. 10.1158/1078-0432.CCR-08-2780.View ArticlePubMedGoogle Scholar
- Sun FX, Tang ZY, Lui KD, Ye SL, Xue Q, Gao DM, Ma ZC: Establishment of a metastatic model of human hepatocellular carcinoma in nude mice via orthotopic implantation of histologically intact tissues. Int J Cancer. 1996, 66: 239-243. 10.1002/(SICI)1097-0215(19960410)66:2<239::AID-IJC17>3.0.CO;2-7.View ArticlePubMedGoogle Scholar
- Rashidi B, An Z, Sun FX, Li X, Tang ZY, Moossa AR, Hoffman RM: Efficacy of intra-hepatectomy 5-FU on recurrence and metastasis of human hepatocellular carcinoma in nude mice. Int J Cancer. 2001, 91: 231-235. 10.1002/1097-0215(200002)9999:9999<::AID-IJC1042>3.3.CO;2-O.View ArticlePubMedGoogle Scholar
- Jia JB, Wang WQ, Sun HC, Liu L, Zhu XD, Kong LQ, Chai ZT, Zhang W, Zhang JB, Xu HX: A novel tripeptide, tyroserleutide, inhibits irradiation-induced invasiveness and metastasis of hepatocellular carcinoma in nude mice. Invest New Drugs. 2011, 29: 861-872. 10.1007/s10637-010-9435-1.View ArticlePubMedGoogle Scholar
- Jia JB, Wang WQ, Sun HC, Zhu XD, Liu L, Zhuang PY, Zhang JB, Zhang W, Xu HX, Kong LQ: High expression of macrophage colony-stimulating factor-1 receptor in peritumoral liver tissue is associated with poor outcome in hepatocellular carcinoma after curative resection. Oncologist. 2010, 15: 732-743. 10.1634/theoncologist.2009-0170.PubMed CentralView ArticlePubMedGoogle Scholar
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