冷冻消融联合TGF-β阻断治疗前列腺癌的有效性及相关机制研究

Cryoablation is an important alternative for prostate cancer. However, the immune escape of tumor cells is the crux for recurrence or metastasis. 1) Our former results confirmed the therapeutic effect and revealed an increasing ratio of Th1/Th2. 2) Our animal experiments showed that the cryoablation for prostate cancer was able to induce the maturition and activation of DC, and increase the CD8+T cell numbers in draining lymph node, which could kill prostate cancer cell specially. All of the results clarified that the cryoablation stimulated the anti-tumor response. However, our clinical research found the obvious increasing of Tregs and TGF-β in peripheral blood after cryoablation. The serum TGF-β level continued to rise at 28 days after treatment, which revealed a immune tolerance microenvironment existed. The increased TGF-β could establish immune tolerance by various pathways. It will promote the immune escape and disease recurrence. Thus, we will focus on the inhibiting immune tolerance by TGF-β blocking,confirm the efficacy of cryoablation combined TGF-β blocking for prostate cancer. The ultimate aim is to provide new molecular target of cryo-immunological response and new clew for the mechnisms of cryo-immunological response.

冷冻消融是治疗前列腺癌有效手段，但癌细胞免疫逃逸导致复发与转移仍是难点。我们前期研究证实:1)冷冻消融取得疗效的同时伴随Th1/Th2比值升高；2)动物实验研究发现冷冻消融杀伤前列腺肿瘤细胞的同时伴有DC的成熟与活化增加，引流淋巴结中CD8+T细胞增多，且特异性杀伤前列腺肿瘤细胞的能力增强，证明冷冻消融已调动机体抗肿瘤免疫反应。然而，我们临床研究发现冷冻消融后前列腺癌患者外周血中调节性T细胞数量和TGF-β含量较术前均明显增加,并持续至术后28天。由于增高的TGF-β可能通过多种途径建立免疫耐受微环境，促进癌细胞逃逸免疫监视，导致肿瘤复发。据此，本项目采用TGF-β单抗阻断其信号通路，证实冷冻消融联合TGF-β阻断治疗前列腺癌的有效性，为调节冷冻免疫提供新靶点，为深入研究冷冻免疫相关机制提供新线索。

研究背景：冷冻消融是治疗前列腺癌的有效手段，前期研究发现：冷冻消融可诱导机体免疫反应，但患者外周血中TGF-β含量和抑制性淋巴细胞均有所增加，增高的TGF-β可能通过多种途径建立免疫耐受微环境，导致肿瘤复发。. 研究内容：(1)冷冻消融对前列腺癌细胞转化生长因子-β及smad通路的影响；(2)冷冻消融联合TGF-β阻断治疗对Treg、MDSCs细胞的影响；(3)冷冻消融联合TGF-β阻断对MDSCs功能的影响。. 研究结果：(1) 细胞冷冻处理后TGF-β1分泌增多，且细胞内TGF-β1、smad2、smad3、smad4蛋白表达水平增高，细胞侵袭迁移能力增强。(2) TGF-β阻断可降低RM-1细胞增殖、侵袭和迁移能力，降低肿瘤负荷和肺转移。冷冻消融联合TGF-β阻断可降低TGF-β1水平，升高IL-2水平，降低Treg细胞和MDSCs细胞比例，增加CD4+T和CD8+T细胞，增强脾脏CTL细胞杀伤活性。(3)冷冻消融联合TGF-β单抗阻断可抑制免疫抑制因子TGF-β、IL-10的释放，促进MDSC向M1型巨噬细胞的优势转化，减弱MDSC向前列腺癌细胞的趋化能力；下调MDSC中Arg-1、iNOS的表达，促进CD4+T细胞向Th1型分化。. 本研究初步证实了冷冻消融联合TGF-β阻断治疗前列腺癌的有效性及相关机制，为调节冷冻免疫提供新靶点，也为深入研究冷冻免疫相关机制提供新线索。