Grzesiak John J, Smith Kathy C, Burton Douglas W, Deftos Leonard J, Bouvet Michael
Veterans Affairs San Diego Healthcare System and the Departments of Surgery, San Diego, Calif.
Surgery. 2007 Jun;141(6):804-14. doi: 10.1016/j.surg.2006.12.016. Epub 2007 May 4.
We have shown recently that alpha(2)beta(1) integrin-mediated type I collagen adhesion promotes a more malignant phenotype in pancreatic cancer cell lines than other extracellular matrix (ECM) proteins. MiaPaCa-2 cells, by contrast, do not express collagen-binding integrins, but are metastatic in our orthotopic mouse model and migrate maximally on laminin-1 (Ln-1). It has also been shown that CXCR4 and IL-8 expression correlates directly with metastasis in pancreatic cancer in vivo. We therefore examined the potential of the ECM to regulate CXCR4 and IL-8 expression in pancreatic cancer cells.
We cultured 8 pancreatic cancer cell lines on fibronectin (Fn), types I and IV collagen, Ln-1 and vitronectin (Vn), and examined cell lysates for CXCR4 by immunoblotting and media for IL-8 by ELISA. We also conducted cell migration assays with stromal-derived factor-1 (SDF-1) as the chemoattractant to examine integrin-binding specificity and CXCR4 function.
All cell lines expressed CXCR4 protein. MiaPaCa-2 cell growth on Ln-1 increased significantly CXCR4 and IL-8 expression relative to other ECM proteins. Migration inhibition studies showed that both the alpha(6)beta(1) and alpha(3)beta(1) integrins mediate MiaPaCa-2 migration on Ln-1. Growth studies showed further that CXCR4 expression on Ln-1 was mediated by the alpha(6)beta(1) integrin whereas IL-8 expression was mediated by both the alpha(6)beta(1) and alpha(3)beta(1) integrins. The expression of functional CXCR4 was also shown in migration assays, where SDF-1 significantly increased pancreatic cancer cell chemotaxis on Ln-1.
These data indicate that integrin-mediated Ln-1 adhesion upregulates CXCR4 and IL-8 expression and may play a mechanistic role in pancreatic cancer metastases.
我们最近发现，与其他细胞外基质（ECM）蛋白相比，α(2)β(1)整合素介导的I型胶原黏附可促进胰腺癌细胞系表现出更恶性的表型。相比之下，MiaPaCa-2细胞不表达胶原结合整合素，但在我们的原位小鼠模型中具有转移性，并且在层粘连蛋白-1（Ln-1）上迁移能力最强。研究还表明，CXCR4和IL-8的表达与胰腺癌体内转移直接相关。因此，我们研究了ECM调节胰腺癌细胞中CXCR4和IL-8表达的可能性。
我们将8种胰腺癌细胞系培养在纤连蛋白（Fn）、I型和IV型胶原、Ln-1和玻连蛋白（Vn）上，通过免疫印迹检测细胞裂解物中的CXCR4，并通过酶联免疫吸附测定（ELISA）检测培养基中的IL-8。我们还以基质衍生因子-1（SDF-1）作为趋化剂进行细胞迁移试验，以检测整合素结合特异性和CXCR4功能。
所有细胞系均表达CXCR4蛋白。相对于其他ECM蛋白，MiaPaCa-2细胞在Ln-1上生长可显著增加CXCR4和IL-8的表达。迁移抑制研究表明，α(6)β(1)和α(3)β(1)整合素均介导MiaPaCa-2细胞在Ln-1上的迁移。进一步的生长研究表明，Ln-1上CXCR4的表达由α(6)β(1)整合素介导，而IL-8的表达由α(6)β(1)和α(3)β(1)整合素共同介导。在迁移试验中也显示了功能性CXCR4的表达，其中SDF-1显著增加了胰腺癌细胞在Ln-1上的趋化作用。
这些数据表明，整合素介导的Ln-1黏附上调了CXCR4和IL-8的表达，可能在胰腺癌转移中发挥机制性作用。
