An antimicrobial peptide regulates tumor-associated macrophage trafficking via the chemokine receptor CCR2, a model for tumorigenesis.
BACKGROUND
Tumor-associated macrophages (TAMs) constitute a significant part of infiltrating inflammatory cells that are frequently correlated with progression and poor prognosis of a variety of cancers. Tumor cell-produced human beta-defensin-3 (hBD-3) has been associated with TAM trafficking in oral cancer; however, its involvement in tumor-related inflammatory processes remains largely unknown.


METHODS
The relationship between hBD-3, monocyte chemoattractant protein-1 (MCP-1), TAMs, and CCR2 was examined using immunofluorescence microscopy in normal and oral carcinoma in situ biopsy specimens. The ability of hBD-3 to chemoattract host macrophages in vivo using a nude mouse model and analysis of hBD-3 on monocytic cell migration in vitro, applying a cross-desensitization strategy of CCR2 and its pharmacological inhibitor (RS102895), respectively, was also carried out.


CONCLUSIONS
MCP-1, the most frequently expressed tumor cell-associated chemokine, was not produced by tumor cells nor correlated with the recruitment of macrophages in oral carcinoma in situ lesions. However, hBD-3 was associated with macrophage recruitment in these lesions and hBD-3-expressing tumorigenic cells induced massive tumor infiltration of host macrophages in nude mice. HBD-3 stimulated the expression of tumor-promoting cytokines, including interleukin-1alpha (IL-1alpha), IL-6, IL-8, CCL18, and tumor necrosis factor-alpha (TNF-alpha) in macrophages derived from human peripheral blood monocytes. Monocytic cell migration in response to hBD-3 was inhibited by cross-desensitization with MCP-1 and the specific CCR2 inhibitor, RS102895, suggesting that CCR2 mediates monocyte/macrophage migration in response to hBD-3. Collectively, these results indicate that hBD-3 utilizes CCR2 to regulate monocyte/macrophage trafficking and may act as a tumor cell-produced chemoattractant to recruit TAMs. This novel mechanism is the first evidence of an hBD molecule orchestrating an in vivo outcome and demonstrates the importance of the innate immune system in the development of tumors.
Jin
Ge
G
Department of Biological Sciences, Case Western Reserve University School of Dental Medicine, Cleveland, Ohio, USA. ge.jin@case.edu
Kawsar
Hameem I
HI
Hirsch
Stanley A
SA
Zeng
Chun
C
Jia
Xun
X
Feng
Zhimin
Z
Ghosh
Santosh K
SK
Zheng
Qing Yin
QY
Zhou
Aimin
A
McIntyre
Thomas M
TM
Weinberg
Aaron
A
D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic; D008264:Macrophages / Q000187:drug effects*; D051379:Mice; D008819:Mice, Nude; D008856:Microscopy, Fluorescence; D009374:Neoplasms, Experimental / Q000473:pathology*; D010455:Peptides / Q000494:pharmacology*; D021381:Protein Transport; D054390:Receptors, CCR2 / Q000378:metabolism*
D000890:Anti-Infective Agents; C515335:Ccr2 protein, mouse; D010455:Peptides; D054390:Receptors, CCR2