Ratliff T L, Palmer J O, McGarr J A, Brown E J
Cancer Res. 1987 Apr 1;47(7):1762-6.
Intravesical Bacillus Calmette-Guérin (BCG) is considered to be one of the most effective treatments for superficial bladder cancer. Although the mechanisms by which BCG inhibits tumor growth are not known, previous studies have shown that systemic immunization to BCG and the local expression of the immune response in the bladder are associated with a favorable response to BCG therapy. We have investigated the conditions required for the initiation of an immunological response after the intravesical instillation of BCG. Initial histological studies showed that BCG attached to the bladder wall only in areas where the urothelium was damaged by electrocautery and suggested that attachment was associated with the fibrin clot. Quantitative studies verified the histological observations. Minimal BCG attachment (mean less than 10(2) colony forming units) was observed in normal bladders in contrast with a mean of 1.42 X 10(4) colony forming units/bladder in bladders damaged by electrocautery (10 separate experiments). BCG attachment to the bladder wall was durable since organisms were observed in bladders 48 h after instillation. To investigate the proteins to which BCG attached, we tested the binding of BCG to extracellular matrix and inflammatory proteins which comprise a significant portion of the fibrin clot. BCG bound in vitro to coverslips coated in vivo with extracellular matrix proteins but did not bind to control albumin-coated coverslips. BCG also bound to coverslips coated with purified plasma fibronectin but not to coverslips coated with other purified extracellular matrix proteins including laminin, fibrinogen, and type IV collagen. BCG attachment to coverslips coated with either extracellular matrix proteins or purified fibronectin was inhibited by antibodies specific for fibronectin. Moreover, BCG attachment to cauterized bladders in vivo was inhibited by antifibronectin antibodies. These results demonstrate that fibronectin mediates the attachment of BCG to surfaces and suggest that it is the primary component mediating attachment within the bladder. Moreover, the data suggest that the BCG-fibronectin interaction may be a requisite first step for the initiation of the antitumor activity in intravesical BCG for bladder cancer.
膀胱内灌注卡介苗（BCG）被认为是浅表性膀胱癌最有效的治疗方法之一。尽管BCG抑制肿瘤生长的机制尚不清楚，但先前的研究表明，对BCG的全身免疫以及膀胱中免疫反应的局部表达与对BCG治疗的良好反应相关。我们研究了膀胱内灌注BCG后引发免疫反应所需的条件。最初的组织学研究表明，BCG仅附着在经电灼损伤尿路上皮的膀胱壁区域，提示这种附着与纤维蛋白凝块有关。定量研究证实了组织学观察结果。与经电灼损伤的膀胱平均每膀胱1.42×10⁴集落形成单位相比，正常膀胱中观察到的BCG附着极少（平均少于10²集落形成单位）（10个独立实验）。由于在灌注后48小时的膀胱中仍观察到BCG菌，因此BCG在膀胱壁上的附着是持久的。为了研究BCG附着的蛋白质，我们测试了BCG与构成纤维蛋白凝块很大一部分的细胞外基质和炎症蛋白的结合。BCG在体外与体内涂有细胞外基质蛋白的盖玻片结合，但不与对照白蛋白包被的盖玻片结合。BCG还与涂有纯化血浆纤连蛋白的盖玻片结合，但不与涂有其他纯化细胞外基质蛋白（包括层粘连蛋白、纤维蛋白原和IV型胶原）的盖玻片结合。针对纤连蛋白的特异性抗体可抑制BCG与涂有细胞外基质蛋白或纯化纤连蛋白的盖玻片的结合。此外，抗纤连蛋白抗体可抑制体内BCG与电灼膀胱的附着。这些结果表明纤连蛋白介导BCG与表面的附着，并提示它是介导膀胱内附着的主要成分。此外，数据表明BCG-纤连蛋白相互作用可能是膀胱内BCG治疗膀胱癌启动抗肿瘤活性的必要第一步。
