Inhibition of metastasis-initiating cells by chimeric polypeptide nanoparticles

描述（由申请人提供）：目前只有不到10%的转移性肿瘤是可治愈的，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药物载体系统，以改善癌症转移的治疗。K99/R00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），它在药物偶联后自组装成纳米颗粒，与游离药物相比，它具有较长的循环半衰期和良好的肿瘤蓄积性。根据以下观察结果，候选人假设转移起始细胞（mic）的侵袭行为可以利用cp基纳米颗粒装载抗mic药物盐霉素（salinomycin, Sali）进行药物递送：(a)纳米级药物载体在肿瘤血管周围区域积聚；(b) MICs通过血管周围空间迁移并侵入血管是其转移的第一步，(c) MICs依赖于局部细胞外基质（ECM）中有效的肽酶活性来降解ECM，促进其迁移。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Sali的CP纳米颗粒专门针对mic。这一提议的总体假设将通过以下三个目标进行验证：(1)Sali将与一系列具有不同组成、物理化学性质和分子量的CPs偶联，以系统地改变CP-Sali偶联物的体内稳定性；(2)吸附引发CP-Sali偶联物自组装成直径小于100 nm的粒子，并对其体内稳定性进行定量分析；(3)侵袭相关蛋白酶基质金属蛋白酶2 （MMP2）的肽底物将被整合到CP的初级氨基酸序列中，由此产生的MMP2依赖性切割、细胞摄取、细胞毒性和CP(MMP2)-sali偶联物的转移抑制活性将被研究。提出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者，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优秀的前期培训和研究生产力支持的。通过这项职业发展奖励，候选人将：(1)在Ashutosh 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方面的知名研究者；(2)与职业咨询委员会密切互动，在委员会指导下完成职业转型；(3)产生研究成果，这些成果不仅可以作为他将来申请联邦资助癌症纳米技术的基础。这项研究与公共卫生相关，因为它将导致一种治疗癌症转移的创新治疗策略。

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.