舒尼替尼与多巴胺联合治疗耐药性乳腺癌的机理及药物动力学/药效动力学研究

Drug resistance is one of the most important scientific issues that need to be solved in breast cancer chemotherapy. The growing research shows that breast cancer stem cells (CSCs) are responsible for breast cancer resistance, relapse and metastasis. Consequently, therapies targeting CSCs have received increasing attention. Previous studies found that dopamine receptors (DR) express specifically on the surface of CSC, while there is little or no expression of DR on normal human pluripotent stem cells. Therefore, DR is likely to be a novel promising target in CSC-targeted therapies. Whether dopamine (an agonist of DR) may contribute to the treatment of drug-resistant breast cancer through eradicating CSCs remains unknown. Besides, although several natural growth models of tumor have been established, modeling of the natural progression of CSC in tumor has not been reported yet. In our preliminary experiments, we found that dopamine combined with sunitinib, a vascular endothelial growth factor receptor (VEGFR) inhibitor, significantly inhibited tumor growth, and dopamine reduced the CSC frequency (cells with phenotype of CD44+/CD24-) in BCSCs. Based on the inspiring results, we are planning to move forward (1) to investigate the in vitro inhibitory effects of dopamine, sunitinib alone and in combination on the proliferation of MCF-7, MCF-7/Adr, CSCs and the mechanisms behind it; (2) to investigate the antitumor effects of the two drugs alone and in combination on female BALB/c nude mice bearing MCF-7/Adr and CSC xenografts respectively, which include drug effect on tumor volume, mice weight, overall survival, and the CSC frequency or DR expression in the tumor tissue, and to elucidate the corresponding anticancer mechanisms; (3) to evaluate the pharmacokinetic characteristics of the two drugs alone and in combination, to establish the CSC disease model that describes the natural progression of CSC, and to further establish different types of PK/PD models, in which tumor volume, the CSCs frequency, and overall survival are used as pharmacodynamic indicators separately or integratedly. Those models are supposed to describe the synergistic effect of the combination therapy quantitatively, interpret the role of targeting CSCs in the treatment of drug-resistant breast cancer, and predict optimized dosage regimens of the two drugs through simulation. It is our expectation that the results from conducting the proposed research project could contribute greatly to (i) provide a brand new D1 target and a promising combination therapy of dopamine and other antitumor drugs for improving therapeutic efficacy of drug-resistant breast cancer, and to (ii) offer the modeling method for treatment of other resistant cancers based on the natural growth model of CSC. Furthermore, our future investigation will provide beneficial information to our understanding of drug-resistant cancers, thus suggesting a broad application prospect.

耐药性问题是乳腺癌药物治疗急需解决的科学问题，靶向癌症干细胞(CSC)是根治肿瘤耐药新策略。多巴胺受体(DR)特异表达于CSC而有望成为CSC新靶点。DR激动剂多巴胺(DA)靶向CSC而辅助治疗耐药性乳腺癌、以及CSC自然进展模型化研究尚属空白。通过前期研究和文献调研提出假设：DA作用于CSC，它和抗癌药舒尼替尼(SUN)合用可治疗耐药性乳腺癌。本研究拟通过流式细胞分析等方法考察乳腺癌细胞及肿瘤组织中CSC比例及DR表达；考察两药单用及联用对乳腺癌细胞增殖的抑制、以及在耐药荷瘤鼠中DA对SUN的增效作用及机理；评价其药动学(PK)和药效学(PD)性质；建立CSC疾病进展模型与基于不同药效指标的PK/PD模型，定量说明靶向CSC在耐药性肿瘤治疗中的作用，通过模型仿真来预测两药联用的优化方案。课题将为耐药性乳腺癌治疗提供新靶点和极具应用前景的DA联用方案，CSC模型建立具有重要理论和实践意义。

耐药性是肿瘤治疗急需解决的科学问题，癌症干细胞(CSC)是引起耐药的关键因素，将抗CSC药物与抗癌药联用使根治肿瘤成为可能。多巴胺受体(DR)特异表达于CSC而有望成为抗CSC新靶点。本项目以多巴胺(DA)等作为抗CSC药物，旨在研究其与舒尼替尼(SUN)等抗癌药联合治疗耐药性肿瘤的机理并建立PK/PD模型。.主要研究内容：①体外药效学及机理研究：考察抗癌药SUN、DA单用与联用对MCF-7、MCF-7/Adr及乳腺癌干细胞(BCSC)的体外药效及CSC等相关机理；②体内药效学及机理研究：建立MCF-7/Adr和BCSC接种的荷瘤裸鼠模型，考察不同剂量下SUN、DA单用以及两药联用对肿瘤体积和瘤内CSC 比例的影响，并引入D1DR特异性拮抗剂确认DA抗CSC靶点等相关机理；③PK/PD模型研究：整合PK和PD数据，建立基于肿瘤生长和CSC比例的PK/PD模型并对模型进行验证和仿真应用；④拓展研究：在SUN+DA联用的基础上，将抗癌药拓展为阿西替尼(AX)和地塞米松(DEX)、抗CSC药物拓展为舒必利(SUL)和激动D1DR的新化合物C2、并将乳腺癌拓展到非小细胞肺癌和胰腺癌，进一步从药效、机理和PK/PD模型对原研究结论进行确认。.重要结果和数据：①证实了DA、SUL和C2具有抑制CSC的新功能；②证实了DA、C2通过激动D1DR亚型抑制CSC，SUL通过拮抗D2DR亚型抑制CSC，不同亚型DR的激动或拮抗对CSC产生的效应不同，说明多巴胺受体(DR)可以用作CSC新靶点；③证实了SUN、AX等抗癌药物增加瘤内CSC是其造成耐药的主要原因，而DA等DR配体可通过诱导细胞凋亡、抑制Wnt信号分子等机理降低CSC比例，与SUN等合用对耐药性肿瘤治疗具有协同作用；④所建CSC和DTC自然生长模型以及药物作用的PK/PD模型能定量阐释CSC和DTC的生长过程、两者的相互转换速率以及药物作用机制，通过模型仿真得到两药联用能同时抑制肿瘤生长和CSC比例的优化方案。.研究意义：该研究提供了抗CSC新靶点、靶向CSC的新药物和优化的联合给药方案，为耐药性肿瘤的临床治疗提供重要参考。.