Inhibition of metastasis-initiating cells by chimeric polypeptide nanoparticles

描述(申请人提供)：只有不到10%的转移性肿瘤可以通过目前的治疗方法治愈，这一事实证明需要更有效的策略来治疗这些肿瘤。该项目的总体目标是开发一种纳米级的药物载体系统，以提高癌症转移的治疗效果。K99/R00提案的申请人最近设计了一种新型多肽药物载体-嵌合多肽(CP)，它通过药物结合自组装成纳米颗粒，与游离药物相比，具有较长的循环半衰期和良好的肿瘤蓄积。候选假设认为，转移启动细胞(MICS)的侵袭行为可用于通过负载抗MIC药物盐霉素(SalI)的CP纳米粒进行药物传递：(A)纳米级药物载体积聚在肿瘤的血管周围区域；(B)MICS在转移中的第一步通过血管周围空间迁移并侵入血管；(C)MICs依赖局部细胞外基质(ECM)中强大的肽酶活性来降解ECM促进它们的迁移。我们将利用这三个事实来设计一种纳米级的传递系统，通过负载Sali的CP纳米颗粒来特定地靶向MIC。这一提议的总体假设将通过以下三个目标进行检验：(1)Sali将与一系列组成、理化性质和分子量不同的CP偶联，以系统地改变CP-Sali偶联物的体内稳定性；(2)CP-Sali偶联物的附着触发自组装成直径小于100 nm的粒子，并对其体内稳定性进行量化；(3)将侵袭相关蛋白的多肽底物基质金属蛋白酶2(MMP2)加入到CP的一级氨基酸序列中，并研究其依赖于MMP2的切割、细胞摄取、细胞毒性和CP(MMP2)-SALi结合物的转移抑制活性。提出的药物载体系统将是第一个利用MICs的流动性进行药物传递的系统，这项研究可能会导致一种治疗癌症转移的新方法。应聘者的总体职业目标是成为一名在纳米技术和癌症治疗的接口上做出贡献的独立研究员。这一目标得到了应聘者出色的前期培训和研究效率的支持。通过这个职业发展奖，候选人将：(1)在AShuosh Chilkoti博士和Mark W.Dewhirst博士的指导下获得额外的培训，他们分别是纳米技术和癌症治疗领域的知名研究人员；(2)与他的职业咨询委员会密切互动，并在该委员会的指导下完成职业过渡；(3)产生研究成果，这些成果不仅是他申请未来癌症纳米技术联邦资金的基础。这项研究与公共健康相关，因为它将导致治疗癌症转移的创新治疗策略。 公共卫生相关性：这项研究项目与公共健康相关，因为该项目的成果将导致更好的治疗策略的创新，以防止肿瘤转移，所产生的知识对未来抗转移治疗的发展有价值。该研究项目还为未来的癌症纳米技术研究科学家提供了培训机会。

DESCRIPTION (provided by applicant): Less than 10% of metastatic tumors are curable by current therapies, a fact that warrants the need for more effective strategies to treat these tumors. The overall goal of this project is to develop a nanoscale drug carrier system to improve therapy of cancer metastases. The applicant of this K99/R00 proposal recently designed a novel polypeptide drug carrier, chimeric polypeptides (CP), which self-assembles into nanoparticles upon drug conjugation, and which displays a long circulation half-life and good accumulation in tumors, as compared to free drug. The candidate hypothesizes that the invasive behaviors of metastasis-initiating cells (MICs) can be utilized for drug delivery using CP-based nanoparticles loaded with an anti-MIC drug, salinomycin (Sali) base on the following observations: (a) nanoscale drug carriers accumulate in the perivascular region of tumors; (b) MICs migrate through the perivascular space and invade a blood vessel as their first step in metastasis, and (c) MICs rely on potent peptidase activities in the local extracellular matrix (ECM) to degrade the ECM facilitate their migration. We will leverage these three facts to design a nanoscale delivery system that specifically targets MICs via a CP nanoparticle that is loaded with Sali. The overall hypothesis of this proposal will be tested by the following three aims: (1) Sali will be conjugated with a range of CPs with varied composition, physico-chemical properties and molecular weights to systematically vary the in vivo stability of the CP-Sali conjugate; (2) the attachment triggered self-assembly of the CP-Sali conjugates into sub-100 nm diameter particles and their in vivo stability will be quantified; (3) a peptide substrate of an invasion-associated proteinase, matrix metalloproteinase 2 (MMP2), will be incorporated into the primary amino acid sequence of the CP, and the resulting MMP2-dependent cleavage, cellular uptake, cytotoxicity, and the metastasis-inhibitory activity of CP(MMP2)-sali conjugates will be studied. The proposed drug carrier system will be the first to exploit the mobility of MICs for drug delivery, and the study may lead to a novel therapy for cancer metastases. The overall career goal of the candidate is to become an independent investigator contributing at the interface of nanotechnology and cancer therapy. This goal is backed by candidate's excellent prior training and research productivity. Through this career development award, the candidate will: (1) acquire additional training under the mentorship of Dr. Ashutosh Chilkoti and Dr. Mark W. Dewhirst, who are well-known investigators in nanotechnology and cancer therapy, respectively; (2) closely interact with his career advisory committee and accomplish career transition under the guidance of the committee; (3) produce research results, which serve not only as a foundation for him to apply for future federal funding on cancer nanotechnology. This research is relevant to public health because it will lead to an innovative therapeutic strategy for the treatment of cancer metastasis. PUBLIC HEALTH RELEVANCE: This research project is relevant to public health because the achievements of this project will lead to innovation of a better therapeutic strategy to prevent tumor metastasis, and the knowledge generated is valuable for future development of the anti-metastasis therapy. The research project also provides training opportunity for future scientists in cancer nanotechnology research.