基于Src通路研究BPN靶向PTP1B抑制神经胶质瘤生长的分子机制

Protein tyrosine phosphatase 1B (PTP1B) is a therapeutic target for type 2 diabetes and obesity. Recent studies have shown that PTP1B is also associated with tumorigenesis and progression. In the early stage, we analyzed the expression of PTP1B in glioma and para-carcinoma tissue and found that it was highly expressed in gliomas and was negatively correlated with the prognosis of patients. Down-regulation of PTP1B expression inhibits cell proliferation and tumor growth. BPN is a specific inhibitor of PTP1B derived from red alga Rhodomela confervoides, which can effectively inhibit the enzymatic activity of PTP1B without affecting other PTPs enzyme activity. In this study, BPN was used as a molecule probe to inhibit intracellular PTP1B activity. The mechanisms of BPN inhibits Glioma growth and the effects of PTP1B on the proliferation and metastasis of glioma cells were investigated by establishing PTP1B overexpression, deletion of cell lines and tumor-bearing mice. The regulation effect of PTP1B on Src and its mediated signaling pathway was studied by means of protein interaction and immunoprecipitation. This study will clarify the role of PTP1B in glioma and the molecular mechanism of BPN anti-tumor, which is of great significance for the discovery of new therapy target for Glioma therapy.

蛋白酪氨酸磷酸酶1B（PTP1B）是2型糖尿病和肥胖症的治疗靶点。最近研究发现，PTP1B与肿瘤发生、发展密切相关。前期，我们分析了PTP1B在神经胶质瘤中的表达，发现其在肿瘤组织中高表达，与病人的恶性程度呈正相关与预后呈负相关。下调PTP1B表达，将抑制细胞增殖和肿瘤形成，表明其有望成为胶质瘤治疗新靶点。BPN为松节藻来源的PTP1B抑制剂，能够进入细胞膜特异性抑制PTP1B的酶活性，且具有血脑屏障通透性，是研究脑肿瘤的良好小分子探针。本研究将以BPN为分子探针，通过建立的PTP1B过表达、缺失表达的细胞株及肿瘤小鼠探讨PTP1B在调控神经胶质瘤生长中的作用及BPN靶向PTP1B对神经胶质瘤的治疗作用；通过蛋白互作、免疫共沉淀等方法研究PTP1B对Src及其介导的信号通路的调控作用。通过本研究将明确PTP1B在神经胶质瘤中的作用及BPN抗肿瘤的分子机制，这对胶质瘤新靶点发现具有重要意义。

PTP1B是蛋白酪氨酸磷酸酶（PTP）家族成员之一，是一种非受体磷酸酶。近年来多项研究表明PTP1B在肿瘤中起到重要的调控作用，异常表达的PTP1B与癌症病人的恶性程度和预后明显相关。因此，PTP1B抑制剂在肿瘤的治疗中也具有巨大潜力。但PTP1B在神经胶质瘤中的作用还不明确。通过本项目我们研究了PTP1B在神经胶质瘤中的表达特性与疾病的发生发展及药物敏感性直接的关系。结果表明，PTP1B在神经胶质瘤组织中高表达并与远处转移和病理分级呈相关，与预后呈负相关，这说PTP1B是一个潜在的神经胶质瘤早期诊断标志物；另一方面，PTP1B缺失会导致神经胶质母瘤细胞的生长减慢，周期阻滞和迁移抑制，并能阻止移植瘤的体内成瘤和生长，证明PTP1B在神经胶质瘤发展中发挥致癌基因的作用。此外，PTP1B特异性抑制剂BPN及其衍生物HPN能够显著抑制神经胶质瘤细胞的增殖和迁移以及体内肿瘤的生长。小剂量的HPN与替莫唑铵联合使用可以显著增强替莫唑铵对神经胶质瘤荷瘤小鼠的化疗敏感性，这进一步说明PTP1B有望成为神经胶质瘤治疗的新靶点。机制研究表明，PTP1B通过靶向SRC信号通路调控胰腺癌的生长。无论是shRNA还是小分子抑制剂导致的PTP1B抑制都会通过增加SRC的磷酸化致使其活性下降，从而导致AMPK活化，最终抑制AKT, ERK通路。同时，SRC的磷酸化水平下降也会进一步抑制stat3/Jak信号通路的活性，进而抑制神经胶质瘤细胞增殖及转移等恶性表型。总之，这些结果有力的说明了PTP1B作为神经胶质瘤治疗靶点的具有巨大的潜力，靶向PTP1B的抑制剂在神经胶质瘤的治疗中也具有重要研究意义。