Expression of complement protein C5a in a murine m

Authors: DoYeun Kim Carol B Martin Soon Nam Lee Brian K Martin

Publish Date: 2005/05/03

Volume: 54, Issue: 10, Pages: 1026-1037

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Abstract

The C5a anaphylatoxin protein plays a central role in inflammation associated with complement activation This protein is commonly regarded as one of the most potent inducers of the inflammatory response and a C5a peptide agonist was used as a molecular adjuvant However the full length C5a protein has not been tested as a potential tumor therapy In this report we describe the creation of a minigene construct that directs C5a expression to any cell of interest Functional expression could be demonstrated in the murine mammary sarcoma EMT6 When C5a expressing cells were injected into syngeneic mice most C5aexpressing clones had significantly reduced tumor growth Further characterization of a clone expressing low levels of C5a demonstrated that onethird of mice injected with this line had complete tumor regression The mice whose tumors regressed were immune to subsequent challenge with unmodified EMT6 cells suggesting that a component of the innate immune response can be used to augment adaptive immunity Cellular analyses demonstrated that a significant difference in actual tumor cell number could be detected as early as day 10 A block in cell cycle progression was evident at all time points and high levels of apoptosis were observed early in the regression event These data demonstrate that the complement protein C5a can play a significant protective role in tumor immunityThe authors would like to thank the following persons Dr Jenny PY Ting in whose laboratory these experiments were initiated Her help and guidance were invaluable for the completion of these studies Dr J G Frelinger for the gift of EMT6 tumor cells the pHβ construct and the mouse IFNγ gene Dr T Collins for his help in setting up the apoptosis assays and Ting laboratory members for their helpful discussions Dr Scott Barnum for the gift of C5aR antibody This work was supported by an American Cancer Society Seed Grant IRG IN122V administered through the Holden Comprehensive Cancer Center of The University of Iowa

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