慢性应激对外泌体介导肿瘤细胞铂类耐药的影响及其机制探讨

Stress-related hormones, represented by norepinephrine (NE), would be significantly released during cancer patients suffering from chronic psychological stress. Our previous study demonstrated that NE induced cancer cells epithelial-mesenchymal transition (EMT) by means of hypoxia-inducible factor 1α (HIF-1α) up-regulation. In the mean time, NE attenuated the efficacy of platinum drugs and elevated CD63 (a classical exosome marker) expression in cancer cells supernatant. It is reported that HIF-1α promotes microRNA-21 (miR-21) over-expression and stimulates the secretion of exosome containing abundant miR-21. On the one hand, miR-21 mediates cancer cells platinum-resistance through PTEN gene inhibition, EMT induction, resistance-related proteins expression and so on. On the other hand, exosome exports platinum drugs out of cancer cells in the process of exosome secretion and further directly reduces intracellular drug concentration. Therefore, we suppose that chronic stress could promote exosome release and miR-21 expression through HIF-1α up-regulation, leading to cancer cells platinum-resistance. This project will mimic chronic-stressful cancer patients through the establishment of chronic stress model in tumor-bearing mice; observe the effect of chronic stress on platinum-resistance and explore potential mechanisms. To our knowledge, there is no study regarding platinum-resistance reported in this view.

肿瘤患者慢性心理应激状态促进去甲肾上腺素(NE)为代表的压力相关激素释放。我们前期研究发现NE不仅通过HIF-1α诱导肿瘤细胞上皮-间质转化(EMT)，还能增加肿瘤细胞上清中外泌体标志物CD63表达，减弱铂类药物疗效。研究报道HIF-1α可以促进肿瘤细胞microRNA-21(miR-21)过表达以及富含miR-21的外泌体释放。一方面，miR-21可以通过抑制PTEN基因、诱导肿瘤细胞EMT以及上调多种耐药相关蛋白表达导致肿瘤细胞铂类耐药；另一方面，外泌体在释放过程中可以将铂类药物携带至肿瘤细胞外，直接减少细胞内药物浓度。因此我们推测慢性应激状态下NE通过HIF-1α促进外泌体释放，诱导miR-21过表达导致肿瘤细胞铂类耐药。本项目通过构建荷瘤小鼠慢性应激模型，模拟肿瘤患者慢性应激状态，观察慢性应激对铂类药物耐药的影响，并探讨可能机制。目前国内外尚无从这一角度研究肿瘤铂类耐药的报道。

肿瘤患者慢性心理应激状态促进去甲肾上腺素（NE）为代表的压力相关激素释放。我们前期研究发现慢性应激或NE可能会导致肿瘤细胞化疗抵抗。本项目通过构建荷瘤小鼠慢性应激模型，从体内及体外实验验证了慢性应激或NE可诱导肿瘤细胞铂类药物耐药。我们发现在这个过程中HIF-1α发挥了重要作用，故采用慢病毒siRNA构建了干扰HIF-1α基因表达的细胞株，探讨了主要机制可能如下：（1）慢性应激可通过激活肿瘤细胞β肾上腺素能受体（β-AR）而激活下游HIF-1α因子，并进一步诱导外泌体（exosome）释放。伴随着外泌体释放的过程，将药物排出肿瘤细胞，减少细胞内药物浓度而导致铂类耐药。该信号通路为β-AR/HIF-1α/exosome。（2）可通过HIF-1α上调miR-21表达，进而促进P-gp、MRP1等耐药相关蛋白表达，导致肿瘤对铂类药物耐药。该信号通路为β-AR/HIF-1α/miR-21。目前国内外尚无从这一角度研究肿瘤铂类耐药的报道，本项目探讨了慢性应激诱导肿瘤化疗抵抗的现象以及可能的作用机制，为临床的联合治疗提供了新的思路。同时，也从心理学这一方向印证了肿瘤患者的心理状态影响患者预后，为心理社会肿瘤学在临床工作中的开展提供了有力的证据支撑。