Research Area, Institute of Oncology Angel H. Roffo, University of Buenos Aires, Buenos Aires, Argentina.
PLoS One. 2010 Oct 22;5(10):e13571. doi: 10.1371/journal.pone.0013571.
Bacillus Calmette-Guerin (BCG) is the most effective treatment for non-muscle invasive bladder cancer. However, a failure in the initial response or relapse within the first five years of treatment has been observed in 20% of patients. We have previously observed that in vivo administration of an inhibitor of nitric oxide improved the response to BCG of bladder tumor bearing mice. It was described that this effect was due to a replacement of tumor tissue by collagen depots. The aim of the present work was to clarify the mechanism involved in this process.
METHODOLOGY/PRINCIPAL FINDINGS: We demonstrated that BCG induces NIH-3T3 fibroblast proliferation by activating the MAPK and PI3K signaling pathways and also differentiation determined by alpha-smooth muscle actin (alpha-SMA) expression. In vivo, intratumoral inoculation of BCG also increased alpha-SMA and collagen expression. Oral administration of L-NAME enhanced the pro-fibrotic effect of BCG. Peritoneal macrophages obtained from MB49 tumor-bearing mice treated in vivo with combined treatment of BCG with L-NAME also enhanced fibroblast proliferation. We observed that FGF-2 is one of the factors released by BCG-activated macrophages that is able to induce fibroblast proliferation. The involvement of FGF-2 was evidenced using an anti-FGF2 antibody. At the same time, this macrophage population improved wound healing rate in normal mice and FGF-2 expression was also increased in these wounds.
CONCLUSIONS/SIGNIFICANCE: Our findings suggest that fibroblasts are targeted by BCG both directly and through activated macrophages in an immunotherapy context of a bladder murine model. We also described, for the first time, that FGF-2 is involved in a dialog between fibroblasts and macrophages induced after BCG treatment. The fact that L-NAME administration improves the BCG effect on fibroblasts, NO inhibition, might represent a new approach to add to the conventional BCG therapy.
卡介苗（BCG）是治疗非肌肉浸润性膀胱癌最有效的方法。然而，在 20%的患者中，观察到在治疗的前五年内初始反应失败或复发。我们之前观察到，体内给予一氧化氮抑制剂可改善荷膀胱癌小鼠对卡介苗的反应。据描述，这种效果是由于肿瘤组织被胶原沉积物所取代。本研究的目的是阐明该过程中涉及的机制。
方法/主要发现：我们证明，BCG 通过激活 MAPK 和 PI3K 信号通路以及通过表达α-平滑肌肌动蛋白（α-SMA）来确定分化，从而诱导 NIH-3T3 成纤维细胞增殖。体内，BCG 瘤内接种也增加了α-SMA 和胶原的表达。L-NAME 的口服给药增强了 BCG 的促纤维化作用。从 MB49 肿瘤荷瘤小鼠获得的腹腔巨噬细胞，经体内联合 BCG 和 L-NAME 治疗后，也增强了成纤维细胞的增殖。我们观察到 FGF-2 是 BCG 激活的巨噬细胞释放的一种能够诱导成纤维细胞增殖的因子之一。使用抗 FGF2 抗体证实了这种参与。同时，这种巨噬细胞群改善了正常小鼠的伤口愈合率，并且这些伤口中 FGF-2 的表达也增加了。
结论/意义：我们的研究结果表明，在膀胱鼠模型的免疫治疗背景下，BCG 既可以直接靶向成纤维细胞，也可以通过激活的巨噬细胞靶向成纤维细胞。我们还首次描述了 FGF-2 参与 BCG 治疗后诱导的成纤维细胞和巨噬细胞之间的对话。给予 L-NAME 可改善 BCG 对成纤维细胞的作用，即抑制 NO，这可能代表了在常规 BCG 治疗基础上的一种新方法。
