Epidermal growth factor receptor-related protein: a potential therapeutic agent for colorectal cancer.
OBJECTIVE
Epidermal growth factor receptor is frequently implicated in epithelial cancers and is, therefore, being considered as a potential target for therapy. Recently, we reported the isolation and characterization of epidermal growth factor receptor-related protein, a negative regulator of epidermal growth factor receptor. To discern whether epidermal growth factor receptor-related protein could be an effective therapeutic agent for colorectal cancer, we generated epidermal growth factor receptor-related protein fusion protein and studied its effect on the growth of colon cancer cells in vivo and in vitro. We also studied whether epidermal growth factor receptor-related protein expression is altered in colorectal cancer.


METHODS
A 55-kilodalton epidermal growth factor receptor-related protein fusion protein with V5 and His tags was generated in a drosophila expression system and subsequently purified by a His antibody affinity column. Rabbit polyclonal antibodies against epidermal growth factor receptor-related protein were used to examine the expression of epidermal growth factor receptor-related protein.


RESULTS
Epidermal growth factor receptor-related protein expression was found to be high in benign human colonic epithelium but low in adenocarcinoma. Exposure of the colon cancer cell lines HCT-116 and Caco-2 to purified recombinant epidermal growth factor receptor-related protein caused a marked inhibition of proliferation, as well as attenuation of basal and ligand-induced stimulation of epidermal growth factor receptor phosphorylation. Epidermal growth factor receptor-related protein-induced inhibition of proliferation of colon cancer cells was prevented by epidermal growth factor receptor-related protein antibodies. Reduced epidermal growth factor receptor phosphorylation was partly due to sequestration of epidermal growth factor receptor ligands by epidermal growth factor receptor-related protein, resulting in the formation of inactive heterodimers with epidermal growth factor receptor. Intratumoral or subcutaneous (away from the tumor site) injections of purified epidermal growth factor receptor-related protein caused regression of palpable colon cancer xenograft tumors in some severely compromised immunodeficient mice and arrested tumor growth in others.


CONCLUSIONS
We propose that epidermal growth factor receptor-related protein inhibits cellular growth by attenuating epidermal growth factor receptor signaling processes and is an effective therapeutic agent for colorectal cancer.
Marciniak
Dorota J
DJ
Department of Internal Medicine, Wayne State University School of Medicine, Detroit, Michigan, USA.
Moragoda
Lathika
L
Mohammad
Ramzi M
RM
Yu
Yingjie
Y
Nagothu
Kiran K
KK
Aboukameel
Amro
A
Sarkar
Fazlul H
FH
Adsay
Volkan N
VN
Rishi
Arun K
AK
Majumdar
Adhip P n
AP
D000818:Animals; D019556:COS Cells; D018938:Caco-2 Cells; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000235:genetics; D066246:ErbB Receptors; D015972:Gene Expression Regulation, Neoplastic; D006023:Glycoproteins / Q000235:genetics / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D016513:Mice, SCID; D011993:Recombinant Fusion Proteins / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
D006023:Glycoproteins; D011993:Recombinant Fusion Proteins; C512478:EGFR protein, human; D066246:ErbB Receptors