Eph-A4 Plays a Important Role in Metastasis and Invasive Activity of Myeloid Leukemia Cells

Abstract 4819

The Eph receptors are found in a wide range of cancers and correlate with metastasis. However, their precise role in cancer has only started to be addressed. In this study, we investigated the role of Eph-A4 receptor in metastasis and invasive activity of myeloid leukemia cells. We fisr tested the expression of Eph-A4 in eight primary myeloid leukemias imclulding four with extramedullary metastasis and four without it, and leukemia cell line K562 by Real-time PCR and western blotting, then found that Eph- A4 was wildly expressed in myeloid Leukemia cells, especially in myeloid leukemia cells with high invasive activity. To further clarified the question, the stable over-expressing Eph-A4 cell line (K562-EphA4) based the wild K562 cell and pGC lentivirus vector were established to declare the metastasis and invasive activity in myeloid leukemia cells in vitro by trans-well migration assay. The results indicated that the mRNA level and protein expression of Eph-A4 were significantly increased in myeloid leukemias with extramedullary metastasis and K562 cells compared to those without it (P<0.05).After we successfully established the stable over-expressing Eph-A4 cell line, we verified its mRNA level and protein expression were both significantly increased ((P<0.05).Furthermore, RhoA and Rac1/cdc42, which are important adhesion molecules and related to metastasis and invasive activity were both highly expressed in K562-EphA4 cells compared to wild K562 cells (P<0.05). Moreover, the trans-well migration assay showed that cells that migrated to lower chambers and matrigel hydrogel were both increased in K562-EphA4 cells compared to wild K562 cells (5.22±2.11*10⁴/ml vs 13.56±2.70*10⁴ /ml P<0.000;18.07±3.15/cm² vs 28.53±2.50/cm²P<0.000 respectively). Our findings suggest that Eph- A4 is likely to play an important role in the regulation the of myeloid Leukemia through the control of RhoA and Rac1/cdc42 associated signaling, migration and invasive activity, and therefore may represent a novel target for cancer treatment.