Department of Gynecology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, Bldg. N27, 20246 Hamburg, Germany.
J Cancer Res Clin Oncol. 2013 Jan;139(1):107-21. doi: 10.1007/s00432-012-1306-z. Epub 2012 Sep 16.
Expression of the adhesion molecule L1-CAM (L1) has been shown to correlate with early recurrence in breast cancer. Here, we investigated whether L1-CAM expression of breast cancer cells might influence adherence to human pulmonary microvascular endothelial cells (HPMEC) and thus promote metastasis.
MDA-MB231-Fra2 breast cancer cells that express high levels of L1-CAM (L1(high) cells) were stably transfected to generate clones with strong L1-CAM downregulation. Adhesion to activated HPMEC was studied in dynamic cell flow and static assays. Potential binding partners on endothelial cells were identified by blocking experiments and adhesion assays after coating of the flow channels with recombinant proteins.
Adhesion of L1(high) cells to activated HPMEC was significantly higher compared to L1l(ow) clones under flow conditions. Blocking experiments and adhesion assays with recombinant proteins identified activated leucocyte cell adhesion molecule (ALCAM) or L1 itself, but not ICAM-1, as potential binding partners on endothelial cells. E-selectin blocking antibodies strongly diminished the adherence of breast cancer cells irrespective of their L1-CAM expression.
Our experiments indicate that L1-CAM expression on breast cancer cells can promote adherence to activated endothelial cells by binding to endothelial L1-CAM or ALCAM. This mechanism might lead to increased metastasis and a poor prognosis in L1-CAM-positive carcinomas in vivo. Therefore, L1-CAM might be a suitable therapeutic target in breast cancers with a high L1-CAM expression.
已有研究表明，黏附分子 L1-CAM（L1）的表达与乳腺癌的早期复发相关。在此，我们研究了乳腺癌细胞中 L1-CAM 的表达是否会影响其对人肺微血管内皮细胞（HPMEC）的黏附，从而促进转移。
MDA-MB231-Fra2 乳腺癌细胞表达高水平的 L1-CAM（L1（高）细胞），通过稳定转染产生 L1-CAM 强烈下调的克隆。在动态细胞流动和静态测定中研究了对激活的 HPMEC 的黏附。通过阻断实验和在流动通道上涂覆重组蛋白后的黏附实验来鉴定内皮细胞上的潜在结合伴侣。
与 L1（低）克隆相比，在流动条件下，L1（高）细胞与激活的 HPMEC 的黏附明显更高。阻断实验和用重组蛋白进行的黏附实验表明，激活的白细胞细胞黏附分子（ALCAM）或 L1 本身，而不是 ICAM-1，是内皮细胞上的潜在结合伴侣。E-选择素阻断抗体强烈减少了乳腺癌细胞的黏附，而与 L1-CAM 表达无关。
我们的实验表明，乳腺癌细胞上的 L1-CAM 表达可以通过与内皮细胞 L1-CAM 或 ALCAM 结合来促进对激活的内皮细胞的黏附。这种机制可能导致体内 L1-CAM 阳性癌中转移增加和预后不良。因此，L1-CAM 可能是 L1-CAM 表达水平高的乳腺癌的一个合适的治疗靶点。
