Cell adhesion molecule expression and homing of hematologic malignancies

Adhesion molecule profiles of B-cell non-Hodgkin's lymphomas in the leukemic phase

We evaluated the expression of 10 adhesion molecules on peripheral blood tumor cells of 17 patients with chronic lymphocytic leukemia, 17 with mantle-cell lymphoma, and 13 with nodal or splenic marginal B-cell lymphoma, all in the leukemic phase and before the beginning of any therapy. The diagnosis of B-cell non-Hodgkin's lymphomas was based on cytological, histological, immunophenotypic, and molecular biology methods. The mean fluorescence intensity of the adhesion molecules in tumor cells was measured by flow cytometry of CD19-positive cells and differed amongst the types of lymphomas. Comparison of chronic lymphocytic leukemia and mantle-cell lymphoma showed that the former presented a higher expression of CD11c and CD49c, and a lower expression of CD11b and CD49d adhesion molecules. Comparison of chronic lymphocytic leukemia and marginal B-cell lymphoma showed that the former presented a higher expression of CD49c and a lower expression of CD11a, CD11b, CD18, CD49d, CD29, and CD54. Finally, comparison of mantle-cell lymphoma and marginal B-cell lymphoma showed that marginal B-cell lymphoma had a higher expression of CD11a, CD11c, CD18, CD29, and CD54. Thus, the CD49c/CD49d pair consistently demonstrated a distinct pattern of expression in chronic lymphocytic leukemia compared with mantle-cell lymphoma and marginal B-cell lymphoma, which could be helpful for the differential diagnosis. Moreover, the distinct profiles of adhesion molecules in these diseases may be responsible for their different capacities to invade the blood stream.

Expression of integrin beta1 and its roles on adhesion between different cell cycle hepatocellular carcinoma cells (SMMC-7721) and human umbilical vein endothelial cells

To investigate expression of integrin beta1 and its roles on adhesion between different cell cycle hepatocellular carcinoma cell (HCC) and human umbilical vein endothelial cells (HUVEC), the synchronous G1 and S phase HCC were achieved through thymine-2-deoxyriboside and colchicines sequential blockage method and double thymine-2-deoxyriboside blockage method, respectively. Expression of integrin beta1 on hepatocellular carcinoma cells was detected with flow cytometer. Further, the adhesive force of HCC to HUVEC and the role of integrin beta1 in this adhesive course were studied by micropipette aspiration technique. The results showed that percentage of each cyclic phases of the controlled HCC (non-synchronous) are: G2 + M phase, 11%; G1 phase, 54%; S phase, 36%; the synchronous rates of G1 and S phase HCC amount to 74 and 98%, respectively. The expressive fluorescent intensity of integrin beta1 in G1 phase HCC is depressed significantly than the values of S phase and controlled HCC. Accordingly, the adhesive forces of G1 phase HCC to HUVEC was significantly lower than the value of S phase cells (P < 0.01), but it has no remarkable difference when compared the adhesive force values of S phase HCC with control; the contribution of integrin beta1 was about 50% in the adhesion of HCC to HUVEC. It suggested that HCC would be synchronized preferably in G1 and S phase with thymine-2-deoxyriboside and colchicines, the adhesive molecule integrin beta1 expressed in a high lever in HCC and presented differences in vary cell cycle, and integrin beta1 played an important roles in adhesion of HCC to HUVEC. Possibly, S phase HCC take a great action in this adhesive course.

Activation of leukocyte function-associated antigen-1 on adult T-cell leukemia cells

Adult T cell leukemia (ATL) is characterized by massive infiltration of circulating ATL cells into a variety of tissues, a finding often associated with poor prognosis. Leukocyte migration from circulation into tissue depends on integrin-mediated adhesion to endothelium and integrins are tightly regulated by several stimuli such as inflammatory chemokines. We have investigated the mechanisms of extravasation of ATL cells and reported the novel features of endogenous chemokine-induced adhesion of ATL cells to the endothelium. We propose that ATL cells adhere to endothelial cells through an adhesion cascade similar to normal leukocytes, and that the chemokines produced by ATL cells are involved in triggering integrin LFA-1 through cytoskeletal rearrangement induced by G-protein-dependent activation of PI 3-kinases in an autocrine manner. Furthermore, the cell surface heparan sulfate proteoglycan particularly on ATL cells is involved in chemokine-dependent autocrine stimulation of integrin-triggering by immobilizing the chemokine on them. These events result in a strong adhesion of ATL cells to the endothelium and spontaneous transendothelial migration.

Constitutive Chemokine Production Results in Activation of Leukocyte Function-Associated Antigen-1 on Adult T-Cell Leukemia Cells

Adult T-cell leukemia (ATL) is characterized by massive infiltration of circulating ATL cells into a variety of tissues, a finding often associated with poor prognosis. Leukocyte migration from circulation into tissue depends on integrin-mediated adhesion to endothelium, and integrins are tightly regulated by several stimuli, such as inflammatory chemokines. However, the exact mechanisms that enhance adherence of leukemic cells to the endothelium and infiltration into tissues remain to be fully understood. We investigated the mechanisms of extravasation of leukemic cells using ATL cells and report the following novel features of endogenous chemokine-induced adhesion of ATL cells to the endothelium. ATL cells spontaneously adhered to endothelial cells without exogenous stimulation. Integrin leukocyte function-associated antigen-1 (LFA-1) on ATL cells was spontaneously activated. ATL cells produced high amounts of chemokines, macrophage inflammatory protein-1α (MIP-1α), and MIP-1β. Adhesion of ATL cells to endothelial cells and the expression of activated form of LFA-1 were reduced by pretreatment with pertussis toxin, wortmannin, or anti–MIP-1α and MIP-1β antibodies or transfection with antisense of MIP-1α or MIP-1β. Spontaneous polymerization of cytoskeletal F-actin was observed in ATL cells, which was also inhibited by pertussis toxin and wortmannin. We propose that ATL cells adhere to endothelial cells through an adhesion cascade similar to normal leukocytes and that the chemokines produced by ATL cells are involved in triggering integrin LFA-1 through cytoskeletal rearrangement induced by G-protein–dependent activation of phosphoinositide 3-kinases in an autocrine manner. These events result in a strong adhesion of ATL cells to the endothelium and spontaneous transendothelial migration.

Constitutive Chemokine Production Results in Activation of Leukocyte Function-Associated Antigen-1 on Adult T-Cell Leukemia Cells

Adult T-cell leukemia (ATL) is characterized by massive infiltration of circulating ATL cells into a variety of tissues, a finding often associated with poor prognosis. Leukocyte migration from circulation into tissue depends on integrin-mediated adhesion to endothelium, and integrins are tightly regulated by several stimuli, such as inflammatory chemokines. However, the exact mechanisms that enhance adherence of leukemic cells to the endothelium and infiltration into tissues remain to be fully understood. We investigated the mechanisms of extravasation of leukemic cells using ATL cells and report the following novel features of endogenous chemokine-induced adhesion of ATL cells to the endothelium. ATL cells spontaneously adhered to endothelial cells without exogenous stimulation. Integrin leukocyte function-associated antigen-1 (LFA-1) on ATL cells was spontaneously activated. ATL cells produced high amounts of chemokines, macrophage inflammatory protein-1α (MIP-1α), and MIP-1β. Adhesion of ATL cells to endothelial cells and the expression of activated form of LFA-1 were reduced by pretreatment with pertussis toxin, wortmannin, or anti–MIP-1α and MIP-1β antibodies or transfection with antisense of MIP-1α or MIP-1β. Spontaneous polymerization of cytoskeletal F-actin was observed in ATL cells, which was also inhibited by pertussis toxin and wortmannin. We propose that ATL cells adhere to endothelial cells through an adhesion cascade similar to normal leukocytes and that the chemokines produced by ATL cells are involved in triggering integrin LFA-1 through cytoskeletal rearrangement induced by G-protein–dependent activation of phosphoinositide 3-kinases in an autocrine manner. These events result in a strong adhesion of ATL cells to the endothelium and spontaneous transendothelial migration.

L-selectin expression in CD34 positive cells in chronic myeloid leukemia

L-selectin is a cell adhesion molecule, expressed on leukocytes and involved in the regulation of leukocyte traffic. This adhesion receptor is implicated in hematopoiesis by the interaction of hematopoietic stem cells and progenitors to stroma in the bone marrow microenvironment. We found that L-selectin expression on CD34++ cells from patients with chronic myelogenous leukemia (CML) is decreased or deficient, reflecting one of the features of malignant CML progenitors. In this review, we briefly describe the structure and function of L-selectin, and its role in hematopoiesis and its expression in leukemia and lymphoma. Finally, we discuss the abnormal adhesiveness of CML progenitor cells, and the role of L-selectin in this defect.

Heparan sulfate proteoglycan on leukemic cells is primarily involved in integrin triggering and its mediated adhesion to endothelial cells

Leukocyte migration from circulation into tissue depends on leukocyte integrin-mediated adhesion to endothelium, but integrins cannot function until activated. However, it remains to be understood how tumor cells adhere to endothelium and infiltrate into underlying tissue. We studied mechanisms of extravasation of leukemic cells using adult T cell leukemia (ATL) cells and report the following novel features of cell surface heparan sulfate proteoglycan on ATL cells in ATL cell adhesion to endothelium: ATL cells adhere to endothelial cells through already activated integrins without exogenous stimulation; different from any other hematopoietic cells, ATL cells express a characteristic heparan sulfate capable of immobilizing heparin-binding chemokine macrophage inflammatory protein (MIP)-1 beta, a potent T cell integrin trigger, produced by the cells themselves; competitive interruption of endogenous heparan sulfate proteoglycan synthesis reduces cell surface MIP-1 beta and prevents ATL cells from integrin-mediated adhesion to endothelial cells or intercellular adhesion molecule-1 triggered through G-protein. We propose that leukemic cells adhere to endothelial cells through the adhesion cascade, similar to normal leukocyte, and that the cell surface heparan sulfate, particularly on ATL cells, is pivotally involved in chemokine-dependent autocrine stimulation of integrin triggering by immobilizing the chemokine on them.

Flow cytometric detection of CD44 (H-CAM) in hairy cell leukemia

Hairy cell leukemia (HCL) is a rare clonal B-cell disorder characterized by a distinctive pattern of infiltration of hairy cells (HCs) in the bone marrow (BM), hepatic sinusoids and splenic red pulp. HCs express a wide spectrum of matrix-binding integrins, which influence their migratory behaviour and subsequent tissue localization. CD44 distribution and staining intensity on HCs from the BM and peripheral blood (PB) were investigated using dual-color flow cytometry. HCs from all cases expressed CD44, but the staining intensity of the positive population was significantly higher than normal residual lymphocytes (p < 0.0005) and medullary HCs in those patients exhibiting additional hairy cell dissemination in the peripheral blood. It is of interest to speculate that the BM microenvironmental may deliver signals which down-regulate CD44 expression on resident HCs compared to HCs recirculating in peripheral blood. CD44 expression on HCs may help clarify their homing mechanisms in the bone marrow and to define phenotypic subsets with different clinical and pathological behaviours.