CXC Chemokine ligand 12 (CXCL12) mediates multiple myeloma
cell line (RPMI 8226) chemotxis via
PLCβ3, PI3K/AKT, RhoA, NFkB And ERK1/2
Gamal Badr
Department of Zoology, Faculty of Science, King Saud University, Saudi
Arabia.
Fetal Programming of Diseases Research Chair, College of
Science, King Saud University, Saudi Arabia. E-mail:
badr73@yahoo.com. Tel:
+966 509673084.
Fax: 0096614674253.
Accepted 5 July, 2010 |
|
In multiple myeloma (MM) blood-borne malignant plasma cells
home to bone marrow (BM), where they accumulate in close
contact with stromal cells. Nevertheless, the mechanisms
responsible for MM cell chemotaxis are still poorly defined.
In the present study we explored the mechanisms involved in
the chemotaxis of RPMI 8226 cell line, RPMI 8226 cell line
was found to express CCR3, CCR5, CCR9, CXCR3 and CXCR4, but
these cells were migrated only towards CXCL12 (the ligand
for CXCR4). To clarify the signaling pathways involved in
the regulation of MM cell chemotaxis, we therefore analyzed
the effect of various inhibitors targeting intracellular
effectors proteins on the CXCL12-mediated RPMI 8226
chemotaxis using flow cytometry and western blot analysis.
Using flow cytometry, we observed that the chemotaxis of
RPMI 8226 cell to CXCL12 was completely abrogated by adding
AMD (CXCR4 antagonist), PTX (G-protein coupled receptor
inhibitor) and U73122 (phospholipase C beta; PLCβ
inhibitor), moreover, CXCL12-mediated RPMI 8226 chemotaxis
was partially inhibited by 1 µM wortmannin (WM, Class II
PI3K inhibitor)), SH5 (AKT inhibitor), Y27632 (Rho-A
inhibitor), SN50 (IBα inhibitor), PD98059 (ERK1/2 MAPK
inhibitor) and Na3VO4 (phosphatase
inhibitor). These results were further confirmed by using
western blot analysis where we observed that triggering of
CXCR4 by CXCL12 resulted in the activation of PLCβ3, PI3K/AKT,
RhoA, IBα
and ERK1/2. In conclusion, our results revealed that PLCβ3,
PI3K/AKT, RhoA, IKBα
and ERK1/2 are crucial effectors for CXCL12-mediating MM
cell chemotaxis.
Key words: Multiple myeloma cell, chemokine, chemotaxis,
flow cytometry, western blot. |
