Suppression of liver tumor growth and metastasis by adiponectin in nude mice through inhibition of tumor angiogenesis and downregulation of Rho kinase/IFN-inducible protein 10/matrix metalloproteinase 9 signaling.
OBJECTIVE
We aimed to investigate the effects of adiponectin on liver cancer growth and metastasis and explore the underlying mechanisms.


METHODS
An orthotopic liver tumor nude mice model with distant metastatic potential was applied. Either Ad-adiponectin (1 x 10(8); treatment group) or Ad-luciferase (control group) was injected via portal vein after tumor implantation. Tumor growth and metastasis were monitored by Xenogen In vivo Imaging System. Hepatic stellate cell activation by alpha-smooth muscle actin staining, microvessel density by CD34 staining, macrophage infiltration in tumor tissue, and cell signaling leading to invasion, migration [Rho kinase (ROCK), IFN-inducible protein 10 (IP10), and matrix metalloproteinase 9], and angiogenesis [vascular endothelial growth factor (VEGF) and angiopoietin 1] were also compared. Tumor-nontumor margin was examined under electron microscopy. Direct effects of adiponectin on liver cancer cells and endothelial cells were further investigated by a series of functional studies.


RESULTS
Tumor growth was significantly inhibited by adiponectin treatment, accompanied by a lower incidence of lung metastasis. Hepatic stellate cell activation and macrophage infiltration in the liver tumors were suppressed by adiponectin treatment, along with decreased microvessel density. The treatment group had less Ki-67-positive tumor cells and downregulated protein expression of ROCK1, proline-rich tyrosine kinase 2, and VEGF. Tumor vascular endothelial cell damage was found in the treatment group under electron microscopy. In vitro functional study showed that adiponectin not only downregulated the ROCK/IP10/VEGF signaling pathway but also inhibited the formation of lamellipodia, which contribute to cell migration.


CONCLUSIONS
Adiponectin treatment significantly inhibited liver tumor growth and metastasis by suppression of tumor angiogenesis and downregulation of the ROCK/IP10/matrix metalloproteinase 9 pathway.
Man
Kwan
K
Department of Surgery, The University of Hong Kong, Hong Kong, People's Republic of China. kwanman@hkucc.hku.hk
Ng
Kevin T P
KT
Xu
Aimin
A
Cheng
Qiao
Q
Lo
Chung Mau
CM
Xiao
Jiang Wei
JW
Sun
Bai Shun
BS
Lim
Zophia X H
ZX
Cheung
Jerry S
JS
Wu
Ed X
EX
Sun
Chris K W
CK
Poon
Ronnie T P
RT
Fan
Sheung Tat
ST
D052242:Adiponectin / Q000097:blood / Q000494:pharmacology* / Q000627:therapeutic use; D000328:Adult; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000098:blood supply / Q000188:drug therapy* / Q000473:pathology; D045744:Cell Line, Tumor; D054357:Chemokine CXCL10 / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects; D006801:Humans; D008113:Liver Neoplasms / Q000098:blood supply / Q000188:drug therapy* / Q000473:pathology; D008114:Liver Neoplasms, Experimental / Q000098:blood supply / Q000188:drug therapy* / Q000473:pathology; D008175:Lung Neoplasms / Q000517:prevention & control / Q000556:secondary; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009362:Neoplasm Metastasis; D009389:Neovascularization, Pathologic / Q000188:drug therapy*; D015398:Signal Transduction; D023041:Xenograft Model Antitumor Assays; D054460:rho-Associated Kinases / Q000378:metabolism*
D052242:Adiponectin; D054357:Chemokine CXCL10; D054460:rho-Associated Kinases; D020780:Matrix Metalloproteinase 9