Inhibition of metastasis-initiating cells by chimeric polypeptide nanoparticles

描述（由申请人提供）：不到10%的转移性肿瘤可通过当前疗法治愈，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纳米级药物载体系统，以改善癌症转移的治疗。该K99/R 00提案的申请人最近设计了一种新的多肽药物载体，嵌合多肽（CP），其在药物缀合后自组装成纳米颗粒，并且与游离药物相比，其在肿瘤中显示出长的循环半衰期和良好的积累。候选人假设转移起始细胞（MIC）的侵袭行为可以用于使用负载有抗MIC药物盐霉素（Sali）的基于CP的纳米颗粒的药物递送，其基于以下观察：（a）纳米级药物载体在肿瘤的血管周围区域中积累;（B）MIC迁移通过血管周围空间并侵入血管作为其转移的第一步，和（c）MIC依赖于局部细胞外基质（ECM）中的有效肽酶活性来降解ECM，从而促进它们的迁移。我们将利用这三个事实来设计一种纳米级的递送系统，该系统通过装载有Sali的CP纳米颗粒特异性地靶向MIC。本提案的总体假设将通过以下三个目标进行检验：（1）Sali将与一系列具有不同组成、理化性质和分子量的CP偶联，以系统地改变CP-Sali偶联物的体内稳定性;（2）连接触发CP-Sali缀合物自组装成亚-将对100 nm直径的颗粒及其体内稳定性进行定量;（3）将侵袭相关蛋白酶，基质金属蛋白酶2（MMP 2）的肽底物掺入CP的一级氨基酸序列中，并产生MMP 2依赖性切割，将研究CP（MMP 2）-Sali缀合物的细胞摄取、细胞毒性和转移抑制活性。拟议的药物载体系统将是第一个利用MIC的移动性进行药物递送的系统，该研究可能会导致癌症转移的新疗法。候选人的总体职业目标是成为一名独立的研究人员，在纳米技术和癌症治疗的界面做出贡献。这一目标是由候选人的优秀培训和研究生产力的支持。通过这个职业发展奖，候选人将：（1）在Ashutosh Chilkoti博士和Mark W博士的指导下获得额外的培训。Dewhirst，分别是纳米技术和癌症治疗的著名研究者;（2）与他的职业咨询委员会密切互动，并在委员会的指导下完成职业转型;（3）产生研究成果，这不仅是他未来申请癌症纳米技术联邦基金的基础。这项研究与公共卫生有关，因为它将为癌症转移的治疗提供一种创新的治疗策略。 公共卫生相关性：该研究项目与公共卫生相关，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，并且所产生的知识对未来抗转移治疗的发展具有价值。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.