The Study On Extramedullary Infiltration Of Acute Leukemic Cells

1.The expression and the clinical implication of MMP2 on acute leukemic cellsObjective: To study the expression of gelatinase A (MMP2) in acute leukemic cells and its clinical implication. Method: The bone marrow samples from 46 acute leukemia patients were investigated by reverse transcription polymerase chain reaction (RT-PCR) and Gelatin Zymography method. Matrigel invasion assay was studied on U937, NB4, K562 and SHI1 cell lines in vitro. Results: The expression of MMP2 was positive in 24 of 46 patients with AL (52.2%), including 19 of 34 patients with AML(55.9%) and 5 of 12 patients with ALL(41.7%), respectively. In MMP2 positive and negative groups of AL, the extramedullary infiltration rates were 50.0% and 18.2%(P<0. 05), whilst the percentage of immature cell in peripheral white blood cells were 77. 21±13. 9% and 62. 95±17. 2%(P<0. 01), respectively. The matrigel invasion assay suggested that MMP2 is involved in migration of leukemic cells through extracellular matrix (Matrigel). Conclusion: The active form of MMP2 might be essential to the egress of leukemic cells from bone marrow into peripheral blood, followed by an extramedullary infiltration.2. The expression and the clinical significance of CXCR4 on acute leukemic cells Objective: To study the expression of CXCR4 on acute leukemic cells and its clinical significance. Method: The bone marrow samples from 73 acute leukemia patients and leukemic cell lines were investigated by flow cytometry (FCM), the expression of SDF-1 in human marrow stroma cells and meninges were studied using reverse transcription polymerase chain reaction (RT-PCR). Adhesion, migration and invasion assays were studied on U937, NB4 and K562 cell lines in vitro. Results: Thepositive expression of CXCR4 in ALL and AML patients was 65.6% and 17.1%, respectively. And it was 0.2%, 41% and 52% positive on K562, U937 and NB4 cell. The positive expression of CXCR4 on the leukemic cells from the cerebrospinal fluid of an ALL patient, who suffered from central nervous system leukemia , was 97%. In CXCR4 positive and negative groups of ALL, the extramedullary infiltration rates were 61.9% and 18.2%, respectively(P<0. 05), while in AML, the number of peripheral white blood cells in CXCR4 positive group was lower than that of CXCR4 negative group (P<0. 05). We also found that one case human marrow stroma cells and 3 cases meninges expressed SDF-1 a mRNA. In vitro study, SDF1 a can enhance the leukemic cell 's ability of adhesion, migration and invasion. Conclusion: The overexpression of CXCR4 on AL cell may be the molecular mechanism of extramedullary infiltration in leukemia.