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Open Access Research article

Overexpression of chemokine ligand 7 is associated with the progression of canine transmissible venereal tumor

Hsin-Chien Chiang1, Yu-Shan Wang12, Chung-Hsi Chou3, Albert Taiching Liao3, Rea-Min Chu1* and Chen-Si Lin13*

Author Affiliations

1 Animal Cancer Center, School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan

2 Department of Radiation Therapy and Oncology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan

3 School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan

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BMC Veterinary Research 2012, 8:216  doi:10.1186/1746-6148-8-216

Published: 9 November 2012

Abstract

Background

Chemokines play multiple roles in the development and progression in a variety of tumors. Chemokine (C-X-C motif) ligand 7 (CXCL7) has been found associated with pro-inflammatory responses, but its role in cancer growth remains unclear. Our previous study showed that R phase tumor infiltrating lymphocytes (TILs) produced large amounts of interleukin (IL)-6 which antagonized transforming growth factor (TGF)-β derived from CTVT to diminish the immune-suppressive microenvironment. Now we intend to determine the expression pattern of CXCL7 and the role of IL-6/TGF-β in CXCL7 induction during spontaneous progressive (P) and regressive (R) phases in canine transmissible venereal tumor (CTVT).

Results

We have demonstrated that CXCL7 expressed at high level in P phase and down-regulated in R phase by western blot and real-time PCR. This suggested that CXCL7 expression was negatively correlated with the tumor growth. Co-culturing TILs with CTVT cells was found to reduce CXCL7 expression, while adding IL-6 blocking antibody reversed it. Moreover, in P phase CTVT, while IL-1β and TGF-β had no obvious effect on CXCL7 expression, IL-6 was found significantly to reduce CXCL7 expression in a dose-dependent manner. The mRNA expression results of CXCL7 receptor, CXCR2, further confirmed the effects of IL-6 concentration on the CXCL7 expression.

Conclusion

CXCL7 overexpression might be associated with the progressive growth of CTVT. The results shown here also suggest the role of CXCL7 in cancer development and the potential as the anti-cancer therapeutic target.

Keywords:
CXCL7; CXCR2; IL-6; TGF-β; CTVT