| Budget Amount *help |
¥3,690,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2007: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2006: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
The purpose of this study was to investigate the role of DOCK2 in malignant B-cell homing to their microenvironment, as well as in the mechanisms of their survival in the microenvironment. At first, we tried to perform all experiments with primary human B cells. However, when we used those cells, there were too many dead cells just with introducing the DOCK2 siRNA. That made us to change our materials to Ramos, which is human B cell line. We have succeeded to obtain the stable DOCK2 knocked out Ramos with siRNA (ΔDOCK2 Ramos). The spontaneous growth of ΔDOCK2 Ramos appeared to be slightly slower than those transfected empty vector (MOCK Ramos). It was compatible that we saw the reduced ERK phospholyration in ΔDOCK2 Ramos. In addition, the chemotaxis toward SDF-1 was significantly reduced in ΔDOCK2 Ramos than those in MOCK Ramos.
Ramos expresses CD27, which is the marker for mature post germinal center memory B cells. It has been difficult to speculate the role of DOCK2 in those mature cells, as in the knock out mouse study, those mature cells could not differentiate from pre-germinal center B cells because of the luck of ability to home into germinal center. This study disclosed the important role of DOCK2 in the mature human B cells for their chemotaxis in the same way as those of mouse immature system. It has also suggested that DOCK2 might be involved in the survival pathway for human B cells.
At last, we could not see any differences in the expression levels of DOCK2 between human primary B cells and human malignant B cells, such as chronic lymphocytic leukemia, which may imply the difficulties simply to target DOCK2 in the treatment of B cell malignancies.
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