Polymeric Nanomedicines of Small Molecules and miRNA for Treating Pancreatic Canc

描述（由申请人提供）：由于存在明显的促结缔组织增生性肿瘤微环境和出现化疗耐药性，导致复发和转移性扩散，胰腺癌的成功治疗仍然是一个挑战。由于吉西他滨的亲水性和快速代谢，以及由于癌症干细胞（CSC）的活性，吉西他滨仅显示有限的功效，这是由于其对肿瘤的低效递送，癌症干细胞（CSC）的活性由miRNA调节。在我们的初步研究中，将吉西他滨缀合至聚（乙二醇）-嵌段-聚（2-甲基-2-羧基-碳酸亚丙酯）（PEG-PCC）并配制成胶束，当静脉内注射到携带胰腺肿瘤的NSG小鼠中时，与游离药物相比，所述胶束显著抑制肿瘤生长。为了实现完全的肿瘤消退，我们在从吉西他滨耐药MIA PaCa-2 R细胞和人胰腺癌组织分离的CSC的一系列失调的miRNA中鉴定了miR-205，其显著下调，并在调节细胞生长、上皮细胞生长和胰腺癌中起主要作用。 间充质转化（EMT）和抗性。用miR-205模拟物转染MIA PaCa-2 R细胞导致对吉西他滨的化学敏感性恢复。然后，我们合成了具有阳离子链的吉西他滨缀合的聚（乙二醇）-嵌段-聚（2-甲基-2-羧基-碳酸亚丙酯-接枝-十二烷醇-接枝-四亚乙基五胺）共聚物，用于与miR-205模拟物形成聚合复合物，其在胎牛血清中显示出改善的稳定性，并在吉西他滨抗性细胞中有效转染和逆转化学抗性、侵袭和转移。因此，我们假设miR-205模拟物与吉西他滨的共制剂可以通过逆转CSC的化学抗性并同时靶向大量肿瘤细胞来有效治疗胰腺癌。该项目的主要重点是：a）发现合适的miRNA以靶向胰腺癌中的化疗耐药性和EMT（如miR 205），以及B）使用主动靶向纳米载体将该miRNA与吉西他滨共同递送至肿瘤，该主动靶向纳米载体可以保护这两种分子免受血浆降解并确保增强的摄取。我们的具体目的是i）鉴定异常表达的miRNA并验证它们在化学抗性、侵袭和转移中的作用; ii）在聚合物胶束中共配制miRNA和吉西他滨并评估它们对胰腺癌抑制的协同作用，以及iii）评估携带吉西他滨和miRNA的胶束对携带人胰腺肿瘤的小鼠的消退的协同作用。该项目的意义是开发miRNA模拟物和吉西他滨的纳米药物，有效地增加这些肿瘤纤维化基质内的局部药物浓度，并绕过允许肿瘤生长和抑制当前标准化疗疗效的化学耐药机制。

DESCRIPTION (provided by applicant): Successful treatment of pancreatic cancer remains a challenge due to the presence of pronounced desmoplastic tumor microenvironment and emergence of chemoresistance resulting in recurrence and metastatic spread. Gemcitabine shows only limited efficacy due to its inefficient delivery to tumor because of its hydrophilicity and rapid metabolism and also due to the activity of cancer stem cells (CSCs), which are regulated by miRNAs. In our preliminary studies, gemcitabine was conjugated to poly(ethylene glycol)-block-poly(2-methyl-2-carboxyl-propylene carbonate) (PEG- PCC) and formulated into micelles which significantly inhibited tumor growth compared to free drug when injected intravenously into pancreatic tumor bearing NSG mice. To achieve complete tumor regression, we identified miR-205 among a series of dysregulated miRNAs from the CSCs isolated from gemcitabine resistant MIA PaCa-2R cells and human pancreatic cancer tissues, to be significantly downregulated and playing a predominant role in regulating cell growth, epithelial to mesenchymal transition (EMT) and resistance. Transfection of MIA PaCa-2R cells with miR-205 mimic resulted in the restoration of chemosensitivity to gemcitabine. Then, we synthesized gemcitabine conjugated poly(ethylene glycol)-block-poly(2-methyl-2-carboxyl-propylene carbonate-graft- dodecanol-graft-tetraethylenepentamine) copolymer having cationic chains for polyplex formation with miR-205 mimic which showed improved stability in fetal bovine serum and efficiently transfected and reversed chemoresistance, invasion and metastasis in gemcitabine resistant cells. Therefore, we hypothesize that co-formulation of miR-205 mimic with gemcitabine may effectively treat pancreatic cancer by reversing the chemo-resistance of CSCs and simultaneously target bulk tumor cells as well. Major focus of the project is to: a) discover suitable miRNAs to target chemo-resistance and EMT (like miR205) in pancreatic cancer and b) co-deliver this miRNA with gemcitabine to the tumor using a actively targeted nanocarrier which can protect both these molecules from plasma degradation and ensure enhanced uptake. Our specific aims are to i) identify the aberrantly expressed miRNAs and validate their role in chemoresistance, invasion and metastasis; ii) co- formulate miRNA and gemcitabine in polymeric micelles and assess their synergistic effect on the inhibition of pancreatic cancer and, iii) assess the synergistic action of micelles carrying gemcitabine and miRNA on the regression of human pancreatic tumor bearing mice. Significance of the project is to develop nanomedicines of miRNA mimic and gemcitabine that effectively increase local drug concentrations within the fibrotic stroma of these tumors and bypass the chemo-resistant mechanisms that allow tumor growth and inhibit the efficacy of current standard chemotherapies.