Bandyopadhyay Abhik, Wang Long, López-Casillas Fernando, Mendoza Valentín, Yeh I-Tien, Sun LuZhe
Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA.
Prostate. 2005 Apr 1;63(1):81-90. doi: 10.1002/pros.20166.
Transforming growth factor beta (TGFbeta) over-expression in prostate cancer has been shown to promote tumor progression and neo-vascularization. In this study, we have investigated the efficacy and the potential mechanism of a TGFbeta antagonist, a recombinant soluble betaglycan (sBG), as a prostate cancer therapeutic agent after systemic administration in a xenograft model.
Recombinant sBG was delivered continuously via ALZET osmotic pumps or by daily bolus i.p. injection at 4.2 mg/kg/day for 14 days in human prostate cancer DU145 xenograft bearing nude mice. Tumors were analyzed for their size, blood volume by hemoglobin assay, microvessel density (MVD) by CD-31 immunostaining, and apoptosis by TUNEL assay. Matrix metalloproteinase-9 (MMP-9) activity and expression in the DU145 conditioned media were determined by gelatin zymography and Western blotting, respectively. Tissue sections were stained with a polyclonal antibody to MMP-9 using an immuno-fluorescence method.
Continuous or bolus administration of sBG showed a similar significant inhibition of DU145 xenograft growth associated with a reduced tumor blood volume and MVD, and an enhanced intra-tumoral apoptosis. Treatment with sBG inhibited both endogenous and TGFbeta-induced MMP-9 activity and expression in a dose-dependent manner in vitro and reduced in vivo MMP-9 expression in DU145 xenografts.
Our results for the first time indicate that TGFbeta blockade by systemic sBG administration can inhibit DU145 prostate xenograft growth and angiogenesis. The inhibition is likely in part mediated by the attenuation of TGFbeta-induced MMP-9 expression.
前列腺癌中转化生长因子β（TGFβ）的过表达已被证明可促进肿瘤进展和新生血管形成。在本研究中，我们研究了TGFβ拮抗剂重组可溶性β聚糖（sBG）在异种移植模型中全身给药后作为前列腺癌治疗药物的疗效和潜在机制。
在携带人前列腺癌DU145异种移植瘤的裸鼠中，通过ALZET渗透泵连续给予重组sBG，或按4.2 mg/kg/天的剂量每日腹腔注射一次，共14天。分析肿瘤的大小、通过血红蛋白测定法检测血容量、通过CD-31免疫染色检测微血管密度（MVD）以及通过TUNEL测定法检测细胞凋亡。分别通过明胶酶谱法和蛋白质免疫印迹法测定DU145条件培养基中基质金属蛋白酶-9（MMP-9）的活性和表达。使用免疫荧光方法用抗MMP-9多克隆抗体对组织切片进行染色。
连续或推注给予sBG均显示出对DU145异种移植瘤生长的显著抑制作用，同时伴有肿瘤血容量和MVD的降低以及瘤内细胞凋亡的增加。sBG处理在体外以剂量依赖的方式抑制内源性和TGFβ诱导的MMP-9活性和表达，并在体内降低DU145异种移植瘤中的MMP-9表达。
我们的结果首次表明，全身给予sBG阻断TGFβ可抑制DU145前列腺异种移植瘤的生长和血管生成。这种抑制作用可能部分是由TGFβ诱导的MMP-9表达减弱介导的。
