HER2/Src/PP2A信号通路对乳腺癌循环肿瘤细胞生存和转移能力的影响及机制研究

Hematogenous metastasis is the major route of metastasis in breast cancer and also the leading cause for patient death. Circulating tumor cell (CTC) is the source of the transfer. By research, we found that the CTC number was positively correlated with tumor stage in breast cancer patient. HER2 over expression is closely related to distant metastasis of breast cancer, but its mechanism is unknown. It was recently discovered that the activity of PP2A was low in HER2 positive breast cancer, and that PP2A could down-regulate the expression of αⅡbβ3. Src is a key enzyme of PP2A phosphorylation, and PP2A plays an important role in cell proliferation and apoptosis. Hence, we speculate that HER2/Src/PP2A pathway may be involved in the regulation of the biological behavior on breast cancer cell proliferation, apoptosis, and adhesion. In this project, the method of cell filtration (isolated by size of epithelial tumor cells, ISET) combined with laser scanning cytometry (LSC), which was established by us, will be used to detect the expressions of molecules related to HER2/Src/PP2A pathway of CTC in breast cancer patient, and the relationship between their expressions and the patient's clinicopathologic features will be analyzed upon. By in vitro and in vivo studies, the effects of HER2/Src/PP2A pathway intervention will be studied on breast cancer cell proliferation, apoptosis and adhesion, and on metastatic tumor formation in tumor-bearing mice. Through this project, the effects of HER2/Src/PP2A pathway on the survival and metastasic abilities of CTC will be explored in breast cancer patient, which may provide a new avenue for the targeted therapy of breast cancer metastasis.

血行转移是乳腺癌转移的主要途径，也是患者的首要死因。循环肿瘤细胞（CTC）是转移的根源。我们研究发现乳腺癌CTC数目与肿瘤分期正相关。HER2高表达与乳腺癌远处转移密切相关，但目前机制不明。最近发现，HER-2阳性乳腺癌的PP2A活性低，PP2A可下调αⅡbβ3活性，而Src是PP2A磷酸化的关键酶，PP2A对细胞增殖凋亡有重要作用。我们推测HER2/Src/PP2A通路可能参与调控乳腺癌细胞增殖、凋亡和粘附等生物学行为。本项目将用我们已建立的膜滤过联合激光扫描仪技术检测乳腺癌患者CTC的HER2/Src/PP2A通路相关分子的表达，分析其与临床病理因素的关系；通过体外和体内研究观察干预该通路对乳腺癌细胞增殖、凋亡和粘附能力的影响，及其对荷瘤鼠转移瘤形成的影响；探讨HER2/Src/PP2A通路对乳腺癌CTC生存和转移能力的影响及其机制，为乳腺癌转移的靶向干预治疗提供新途径。

血行转移是乳腺癌转移的主要途径，循环肿瘤细胞（CTC）是转移的根源。我们研究发现CTC数目的改变，与病情的转归显著相关，可用于转移性乳腺癌患者化疗后疗效评价。CTC检测的敏感性是目前亟待解决的问题。我们采用Vimentin联合CK、EpCAM的多靶点检测，可提高CTC的检出率，有望进一步应用于临床。血小板与CTC的相互作用，在乳腺癌转移过程中发挥重要作用。本研究开发了一种新的肿瘤-血小板粘附检测技术，获国家发明专利，并证实PP2A/整合素信号通路参与了乳腺癌细胞与血小板的粘附，针对该通路的干预措施有望通过抑制血小板与CTC的相互作用，抑制乳腺癌血行转移。乳腺癌细胞由原发灶脱落，进入循环系统成为CTC的过程，受原发灶的炎症微环境驱动。我们研究发现，炎症微环境可通过激活Src信号通路，使PP2Ac Y307位点发生磷酸化，进而抑制抑癌基因PP2Ac的活性。而炎症微环境激活的NF-κB信号通路，则能够抑制PP2Ac表达。Src、NF-κB共同作用，从活性和表达水平分别抑制PP2Ac，进一步激活下游的ERK、JNK、PKC、Akt等激酶信号通路，促进乳腺癌细胞发生EMT及转移。鉴于炎症对乳腺癌的促进作用，我们研究了抗炎药物特立氟胺对乳腺癌细胞的治疗作用。研究显示特立氟胺能够抑制三阴性乳腺癌细胞的生长转移，并逆转激素受体阳性细胞对他莫昔芬耐药。以往研究已证实青蒿素衍生物青蒿琥酯具有抗炎抗肿瘤作用。我们研究发现青蒿琥酯通过诱导自噬抑制乳腺癌细胞增殖，增强表阿霉素对乳腺癌细胞的化疗敏感性。以往研究发现抑癌基因ING4具有抑制炎症信号通路的作用。我们研究发现ING4过表达能够下调Snail1、Snail2，逆转EMT并抑制乳腺癌转移。进一步构建了ING4/p53基因治疗系统，证实其具有抑生长、促凋亡、抗血管生成作用，有可能成为有效的针对乳腺癌的治疗新模式。