Thamilselvan Vijayalakshmi, Basson Marc D
Department of Surgery, John D. Dingell VA Medical Center, Detroit, MI 48201, USA.
Gastroenterology. 2004 Jan;126(1):8-18. doi: 10.1053/j.gastro.2003.10.078.
Few circulating tumor cells implant or cause metastasis. We hypothesized that venous or lymphatic pressure or iatrogenic pressure during resection activates signals governing malignant colonocyte adhesion.
We studied the effect of 15 mm Hg increased pressure for 30 minutes on adhesion of primary human colon cancer cells and SW620 colonocytes to collagen and endothelial cells. We modulated integrin affinity with extracellular cations. We assessed binding affinity by detachment assay; integrin surface expression by flow cytometry; and focal adhesion kinase (FAK), Src, and extracellular signal-regulated kinase (ERK) activation by Western analysis and Src in vitro kinase assay. We inhibited Src (PP2), FAK (small RNA interference, SiRNA, or FRNK transfection), MEK (PD98059), PKC (calphostin C), and actin destabilization (phalloidin).
Pressure and manganese stimulated primary and SW620 colonocyte adhesion to collagen. Pressure also stimulated SW620 adhesion to endothelial monolayers. Pressure strengthened SW620 binding force to matrix without changing integrin surface expression. Pressure activated SW620 FAK and Src, but not ERK. Manganese did not. Calcium-inhibited adhesion but stimulated FAK (but not Src). PP2 prevented pressure activation of Src, Src phosphorylation of FAK576, and pressure-stimulated adhesion but not FAK397 autophosphorylation. FRNK transfection or FAK SiRNA also prevented pressure-stimulated adhesion. FAK SiRNA ablated pressure-activated FAK397, Src, and FAK576 phosphorylation. Neither Src nor FAK inhibition blocked cation effects. Phalloidin prevented pressure-stimulated adhesion. PD98059 or calphostin C did not.
In contrast to divalent cations, extracellular pressure may increase integrin affinity and promote colon cancer adhesion via actin dependent inside-out FAK and Src signals. This mechanotransduced pathway may regulate metastasizing tumor cell adhesion.
很少有循环肿瘤细胞能够着床或引发转移。我们推测，切除过程中的静脉压、淋巴压或医源性压力会激活调控恶性结肠细胞黏附的信号。
我们研究了将压力升高15 mmHg并持续30分钟对原代人结肠癌细胞和SW620结肠癌细胞与胶原蛋白及内皮细胞黏附的影响。我们用细胞外阳离子调节整合素亲和力。通过解离试验评估结合亲和力；通过流式细胞术检测整合素表面表达；通过蛋白质免疫印迹分析和Src体外激酶试验评估粘着斑激酶（FAK）、Src和细胞外信号调节激酶（ERK）的激活情况。我们抑制Src（PP2）、FAK（小RNA干扰、SiRNA或FRNK转染）、MEK（PD98059）、PKC（钙泊三醇）以及肌动蛋白去稳定作用（鬼笔环肽）。
压力和锰刺激原代及SW620结肠癌细胞与胶原蛋白黏附。压力还刺激SW620与内皮细胞单层黏附。压力增强了SW620与基质的结合力，但未改变整合素表面表达。压力激活了SW620的FAK和Src，但未激活ERK。锰则没有这种作用。钙抑制黏附，但刺激FAK（而非Src）。PP2可阻止压力对Src的激活、Src对FAK576的磷酸化作用以及压力刺激的黏附，但不能阻止FAK397的自身磷酸化。FRNK转染或FAK SiRNA也可阻止压力刺激的黏附。FAK SiRNA消除了压力激活的FAK397、Src和FAK576磷酸化。Src和FAK抑制均未阻断阳离子效应。鬼笔环肽可阻止压力刺激的黏附。PD98059或钙泊三醇则不能。
与二价阳离子不同，细胞外压力可能通过肌动蛋白依赖性的由内向外的FAK和Src信号增加整合素亲和力并促进结肠癌黏附。这种机械转导途径可能调节转移肿瘤细胞的黏附。
