纳米银调控TFEB进核的机制及在肿瘤治疗中的应用研究

Transcription factor EB (TFEB) is an master regulator of autophagy and lysosomal biogenesis. When cell was starved, the TFEB which mainly distributed in the cytoplasm translocated to the nucleus and enhanced the expression of a serious of autophagy-related genes. In our previous study, we have reported that silver nanoparticles (Ag NPs) induced autophagy in cancer cells and inhibit that autophagy improved the efficacy of Ag NPs in anti-cancer therapy in vivo and in vitro. Our present study found that the autophagy induced by Ag NPs was caused by inducing TFEB translocation to the nucleus. And TFEB siRNA co-treatment also dramatically enhanced the tumor killing activity of Ag NPs. .We tried to find a more specific way to inhibit the Ag NPs induced- autophagy by exploring the pathway which regulated the translocation of TFEB. And we found the mechanism of TFEB translocation to the nucleus induced by Ag NPs treatment was different from the mechanism by other autophagy inducer treatment, such as starvation. So next we need to do firstly is finding the key modification sites and the kinase which cause TFEB translocation to the nucleus by Ag NPs treatment. Then, we should verify the anti-tumor efficiency of Ag NPs by co-treating with TFEB translocation inhibitor in vitro and in vivo. Inhibition of TFEB translocation may be a more useful strategy for improving the efficacy of Ag NPs in anti-cancer therapy.

转录因子EB（TFEB）是调控自噬和溶酶体生成的重要调控因子，当细胞处于饥饿等状态时，主要分布于细胞质中的TFEB转移到细胞核内，导致一系列与自噬相关的基因表达上调。我们前期研究显示，纳米银颗粒可以显著上调细胞自噬水平，体外和体内实验都表明抑制自噬可以增强纳米银对肿瘤的杀伤。我们后续研究发现纳米银引起自噬是通过诱导TFEB进核导致的，并且TFEB siRNA处理可以显著增强纳米银对肿瘤细胞的杀伤效果。我们试图从调控TFEB进核的机制探究出发，寻找更为有效的抑制纳米材料保护性自噬的方法。结果显示纳米银与饥饿等其他自噬诱导因素引起TFEB进核的机制不同。所以我们接下来需要找到导致TFEB进核的关键修饰位点，以及对TFEB进行修饰，促进其进核的上游激酶。然后将TFEB进核的抑制手段与纳米银联用，在体内外验证这种联合药物的抗肿瘤效果。这可能是一种特异性更强的增强纳米银抗肿瘤效果的联合给药方法。

转录因子EB（TFEB）是调控自噬和溶酶体生成的重要调控因子，当细胞处于饥饿、压力等状态时，主要分布于细胞质中的TFEB转移到细胞核内，诱导一系列与自噬以及溶酶体再生相关的基因表达上调。我们发现纳米银和稀土金属氧化物纳米颗粒都能诱导细胞内TFEB进核，我们分别对不同纳米材料诱导TFEB进核的机制及生物学意义进行了深入的研究。我们发现纳米银通过mTORC1或者ERK1/2信号通路非依赖的方式诱导TFEB S142和S211位点去磷酸化导致TFEB进核。TFEB进核后调控一系列自噬相关的基因表达上调，敲低TFEB表达会减弱纳米银诱导的自噬，且显著增强纳米银对肿瘤细胞的杀伤效果，这不仅证明了TFEB在纳米银诱导保护性细胞自噬方面所起到的重要作用，还为提高纳米银的肿瘤治疗效果提供了一个新的靶点。稀土金属氧化物纳米颗粒处理会诱导细胞内产生溶酶体压力，定位在溶酶体上的mTORC1感知到溶酶体压力后失活，进一步导致TFEB的S142位点去磷酸化，进核调控一系列与溶酶体再生相关基因的表达挽救稀土金属氧化物纳米颗粒造成的溶酶体压力，如果我们敲低TFEB的表达会增强稀土金属氧化物纳米颗粒处理造成的细胞毒性。我们的研究从调控自噬和溶酶体再生两个方面阐释了TFEB对细胞内压力的保护机制，为提高纳米材料抗肿瘤效果提供了一个全新的靶点。