The G-protein-coupled formylpeptide receptor FPR confers a more invasive phenotype on human glioblastoma cells.
BACKGROUND
The G-protein-coupled formylpeptide receptor (FPR) that mediates chemotaxis of phagocytic leucocytes induced by bacterial and host-derived chemotactic peptides is selectively expressed by highly malignant human gliomas and contributes to tumour growth and angiogenesis. As invasion of surrounding normal tissues is one of the important features of tumour malignancy, we investigated the function of FPR in the invasive behaviour of human glioblastoma cells.


METHODS
Cells (FPR(+) and FPR(-)) were isolated by single-cell cloning from a human glioblastoma cell line U-87MG. The FPR expression was assayed by flow cytometry and reverse transcription PCR. The function of FPR was investigated by chemotaxis and calcium flux induced by FPR agonist fMLF. Tumour cell motility was assayed by a wound-healing model in vitro. The growth and invasive phenotype were observed with subcutaneous implantation of tumour cells in nude mice. Over-expression of FPR in FPR(-) cells was performed by transfection of a plasmid vector-containing human FPR gene.


RESULTS
One of the glioma clones F9 that expressed high level of FPR showed a more 'motile' phenotype in vitro as compared with a clone G3 without FPR expression. Although F9 and G3 clones both formed subcutaneous tumours in nude mice, only F9 tumours invaded surrounding mouse connective tissues. Over-expression of FPR in G3 clone (G3F) increased the cell motility in vitro and the capacity of the cells to form more rapidly growing and invasive tumours in nude mice. We further found that, in addition to supernatant of necrotic tumour cells, foetal calf serum and human serum used in culture media contained FPR agonist activity and increased the motility of FPR-expressing glioblastoma cells.


CONCLUSIONS
The expression of FPR is responsible for increased motility of human glioblastoma cells and their formation of highly invasive tumours.
Huang
J
J
Laboratory of Molecular Immunoregulation, Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA. hj3red@gmail.com
Chen
K
K
Chen
J
J
Gong
W
W
Dunlop
N M
NM
Howard
O M Z
OM
Gao
Y
Y
Bian
X-w
XW
Wang
J M
JM
D000818:Animals; D001932:Brain Neoplasms / Q000235:genetics / Q000473:pathology*; D002448:Cell Adhesion / Q000235:genetics; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation; D005909:Glioblastoma / Q000235:genetics / Q000473:pathology*; D006801:Humans; D020782:Matrix Metalloproteinases / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D010641:Phenotype; D044042:Receptors, Formyl Peptide / Q000819:agonists / Q000235:genetics / Q000502:physiology*; D043562:Receptors, G-Protein-Coupled / Q000819:agonists / Q000235:genetics / Q000502:physiology; D014183:Transplantation, Heterologous
C469986:FPR1 protein, human; D044042:Receptors, Formyl Peptide; D043562:Receptors, G-Protein-Coupled; D020782:Matrix Metalloproteinases