Polymeric Nanomedicines of Small Molecules and miRNA for Treating Pancreatic Canc

描述(申请人提供)：胰腺癌的成功治疗仍然是一个挑战，因为显著的促结缔组织肿瘤微环境的存在和化疗耐药的出现导致复发和转移扩散。由于吉西他滨的亲水性和快速新陈代谢，以及受miRNAs调控的肿瘤干细胞(CSCs)的活性，吉西他滨对肿瘤的传递效率低下，因此疗效有限。在我们的初步研究中，吉西他滨被偶联到聚乙二醇聚碳酸酯(PEGPCC)并形成胶束，与游离药物相比，静脉注射到荷瘤的glycol)-block-poly(2-methyl-2-carboxyl-propylene小鼠体内时，显著抑制了肿瘤的生长。为了实现肿瘤的完全消退，我们在从对吉西他滨耐药的MIA Paca-2R细胞和人胰腺癌组织分离的CSCs中分离出一系列异常的miRNAs，发现miR-205基因显著下调，并在调节细胞生长、上皮细胞和胰腺癌组织中发挥主要作用。 间充质转化(EMT)与抵抗。将miR-205模拟物导入MIA PACA-2R细胞，可恢复对吉西他滨的化疗敏感性。然后，我们合成了含有阳离子链的聚(乙烯glycol)-block-poly(2-methyl-2-carboxyl-propylene碳酸酯-接枝十二醇-接枝-四乙五胺)共聚物，用于与miR-205模拟物形成多聚体，提高了吉西他滨在胎牛血清中的稳定性，并有效地转染和逆转了吉西他滨耐药细胞的耐药、侵袭和转移。因此，我们推测miR-205模拟物与吉西他滨的联合制剂可以通过逆转肿瘤干细胞的化疗耐药而有效地治疗胰腺癌，同时也可以靶向肿瘤细胞。该项目的主要重点是：a)找到合适的miRNAs来靶向胰腺癌的化疗耐药和EMT(如miR205)，以及b)使用一种主动靶向的纳米载体将这种miRNA与吉西他滨共同传递到肿瘤中，这种纳米载体可以保护这两种分子免受血浆降解，并确保增强摄取。我们的具体目标是：1)鉴定异常表达的miRNAs，并验证它们在化疗耐药、侵袭和转移中的作用；ii)在聚合物胶束中共同形成miRNA和吉西他滨，并评估它们在抑制胰腺癌方面的协同作用；iii)评估携带吉西他滨和miRNA的胶束在人胰腺癌荷瘤小鼠消退中的协同作用。该项目的意义在于开发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间质中的局部药物浓度，并绕过允许肿瘤生长和抑制当前标准化疗疗效的化疗耐药机制。

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.