Montuori N, Selleri C, Risitano A M, Raiola A M, Ragno P, Del Vecchio L, Rotoli B, Rossi G
Department of Cellular and Molecular Biology and Pathology, Federico II University Medical School, Naples, Italy.
Clin Cancer Res. 1999 Jun;5(6):1465-72.
Lodgement, proliferation, and migration of leukemic cells within bone marrow (BM) microenvironment involves adhesion of these cells to the BM extracellular matrix molecules fibronectin and laminin. The 67-kDa laminin receptor (67LR) is a nonintegrin protein with high affinity for laminin, which plays a critical role in basement membrane invasion and metastasis of cancer cells. By Western blotting, we documented that 67LR was strongly expressed in myelomonocytic THP1 and histiocytic U937 cells and was weakly expressed in promyelocytic HL-60 cells. In HL-60 cells, 67LR expression almost disappeared after retinoic-induced granulocytic differentiation, whereas it strongly increased after phorbol ester-induced monocytic differentiation. We did not detect 67LR expression in normal BM hematopoietic cells, in precursor-B acute lymphoblastic leukemia, in chronic lymphocytic leukemia, or in chronic myeloid leukemia in chronic phase. By contrast, we detected enhanced 67LR expression in 40% of 53 de novo acute myeloid leukemias (AMLs), which frequently exhibited monocytic or myelomonocytic morphology and expressed CD14 and CD11a (P < 0.05). Using a colorimetric assay, we found that the expression pattern of this receptor corresponded to a higher adhesion to laminin; the adhesion was specific because in vitro addition to laminin-coated wells of recombinant 37-kDa laminin receptor precursor (37LRP), which is the cytoplasmic precursor containing both laminin-binding domains of cell surface 67LR, significantly reduced laminin binding of AML cells. The expression of 67LR on AML cell surface did not correlate with other differentiation and integrin antigens such as CD7, CD13, CD33, CD34, CD11b, CD11c, CD49d, CD49e, CD45RA, and CD45RO. In contrast with 67LR behavior in solid tumors, no statistically significant difference was found between 67LR expression and any hematological characteristic of the disease at diagnosis, nor between 67LR expression and outcome of the disease as measured by complete remission rate, disease-free survival, or overall survival. In conclusion, our results indicate that 67LR expression mediates specific adhesion to laminin and that the detection of this molecule may be a valuable addition to other lineage-associated antigens in identifying monocytic-oriented AML.
白血病细胞在骨髓（BM）微环境中的滞留、增殖和迁移涉及这些细胞与BM细胞外基质分子纤连蛋白和层粘连蛋白的黏附。67-kDa层粘连蛋白受体（67LR）是一种对层粘连蛋白具有高亲和力的非整合素蛋白，在癌细胞的基底膜侵袭和转移中起关键作用。通过蛋白质印迹法，我们证明67LR在骨髓单核细胞THP1和组织细胞U937细胞中强烈表达，而在早幼粒细胞HL-60细胞中弱表达。在HL-60细胞中，维甲酸诱导粒细胞分化后67LR表达几乎消失，而佛波酯诱导单核细胞分化后67LR表达强烈增加。我们在正常BM造血细胞、前体B急性淋巴细胞白血病、慢性淋巴细胞白血病或慢性期慢性髓性白血病中未检测到67LR表达。相比之下，我们在53例初发急性髓性白血病（AML）中的40%检测到67LR表达增强，这些病例常表现为单核细胞或骨髓单核细胞形态，并表达CD14和CD11a（P<0.05）。使用比色测定法，我们发现该受体的表达模式与对层粘连蛋白的更高黏附性相对应；这种黏附是特异性的，因为在层粘连蛋白包被的孔中体外添加重组37-kDa层粘连蛋白受体前体（37LRP），它是包含细胞表面67LR的两个层粘连蛋白结合结构域的细胞质前体，可显著降低AML细胞与层粘连蛋白的结合。AML细胞表面67LR的表达与其他分化和整合素抗原如CD7、CD13、CD33、CD34、CD11b、CD11c、CD49d、CD49e、CD45RA和CD45RO无关。与实体瘤中67LR的表现不同，在诊断时67LR表达与该疾病的任何血液学特征之间，以及67LR表达与以完全缓解率、无病生存期或总生存期衡量的疾病预后之间均未发现统计学上的显著差异。总之，我们的结果表明67LR表达介导对层粘连蛋白的特异性黏附，并且该分子的检测可能是在识别单核细胞定向AML中对其他谱系相关抗原的有价值补充。
