High expression of 67-kDa laminin receptor relates to the proliferation of leukemia cells and increases expression of GM-CSF receptor.
OBJECTIVE
The 67-kDa laminin receptor (LR) is a nonintegrin receptor for laminin, a major component of the extracellular matrix. To elucidate the role of LR in leukemia cells, we studied the relationship between the phenotype of leukemia cells and LR expression.


METHODS
The relationship between clinical features of acute myeloid leukemia and expression of LR was examined. LR was overexpressed or suppressed by the introduction of complementary DNA or small interfering RNA for LR in a human leukemia cell line to test the effect of LR on the phenotype of leukemia. Expression of granulocyte-macrophage colony-stimulating factor receptors (GM-CSFR) was also tested in leukemia cells, including clinical samples.


RESULTS
Expression of LR was significantly related to elevation of white blood cell count, lactate dehydrogenase, and survival among acute myeloid leukemia patients. Forced expression of LR enhanced proliferation, cell-cycle progression, and antiapoptosis of leukemia cells associated with phosphorylation of a transcription factor, signal transducer and activator of transcription 5, in the absence of stimulation by laminin. On the other hand, suppression of LR expression had the opposite effects. The number of GM-CSFR increased in leukemia cells overexpressing LR, and there was a significant relationship between the expression of LR and GM-CSFR in acute myeloid leukemia samples.


CONCLUSIONS
These results suggest that LR expression influenced the characteristics of leukemia cells toward an aggressive phenotype and increased the number of GM-CSFR. These changes might be partly related to enhanced GM-CSF signaling.
Hematology and Molecular Medicine Unit, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki, Japan.
Koji
K
Ando
Yasushi
Y
Miyazaki
Yasushi
Y
Sawayama
Shinya
S
Tominaga
Emi
E
Matsuo
Reishi
R
Yamasaki
Yoriko
Y
Inoue
Masako
M
Iwanaga
Daisuke
D
Imanishi
Hideki
H
Tsushima
Takuya
T
Fukushima
Yoshitaka
Y
Imaizumi
Jun
J
Taguchi
Shinichiro
S
Yoshida
Tomoko
T
Hata
Masao
M
Tomonaga
D017209:Apoptosis / Q000502:physiology; D049109:Cell Proliferation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000097:blood / Q000503:physiopathology; D010766:Phosphorylation; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D017474:Receptors, Laminin / Q000378:metabolism*; D050799:STAT5 Transcription Factor / Q000378:metabolism; D014407:Tumor Cells, Cultured
D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D017474:Receptors, Laminin; D050799:STAT5 Transcription Factor