Polymer-Nucleotide Complexes with Cytotoxic Activity

描述（由申请人提供）：在癌症和病毒感染的化疗中有效的核苷类似物（NA）实际上是“前药”，必须首先在体内转化为核苷5′-单磷酸，最后转化为药物的活性形式核苷5′-三磷酸。它们有效地终止DNA合成，并对增殖的癌细胞具有细胞毒性。然而，5'-三磷酸盐形式的治疗性NAs被认为作为一种药物形式太不稳定，不能直接用于癌症化疗。基于初步数据，本研究正在评估的假设是，将抗增殖性NA的5'-三磷酸包封在具有保护性和靶向性的亚微米聚合物载体中，将导致旧药物的一种新的治疗形式。提出的配方和递送系统是基于核苷5'-三磷酸和称为“纳米凝胶”的阳离子载体之间形成的自组装多离子复合物。这种载体由阳离子聚乙烯亚胺和聚乙二醇或波洛沙姆嵌段共聚物的交联网络组成。负载三磷酸核苷酸的纳米凝胶在水介质中形成小的纳米颗粒。配制成颗粒用于全身给药，NA的活性三磷酸盐可以常规地以冻干形式储存，然后在注射前容易分散。纳米凝胶可以保护循环中的三磷酸核苷酸免受酶降解，并显著增加阴离子核苷酸的细胞内转运，否则是无效的。该提案的具体目标是：(1)制定具有更高分散稳定性和酶抗性的聚合物核苷酸复合物，(2)确定聚合物核苷酸复合物是否可以增加核苷酸类似物的细胞毒性作用，以及(3)研究聚合物核苷酸复合物如何增强体内肿瘤的全身治疗。我们将研究一组具有代表性的NA和癌细胞系，并使用小鼠Lewis肺癌模型来验证获得的体外结果。长循环聚合物-核苷酸复合物由于“增强渗透性和滞留性”的作用而表现出更好的肿瘤蓄积。它们也可以被与活跃增殖癌细胞表面受体有亲和力的载体配体修饰，以增强肿瘤或转移淋巴结中细胞毒性NA的选择性积累。药物形式的应用可能有助于防止许多已知的化疗副作用。在这些研究中积累的数据可以直接用于设计更好的细胞毒性核苷酸药物的系统配方。

DESCRIPTION (provided by applicant): Effective in chemotherapy of cancer and viral infections nucleoside analogues (NA) are actually 'prodrugs', which must be first converted in vivo into nucleoside 5'-monophosphates and, finally, into the drug's active form, nucleoside 5'-triphosphates. They efficiently terminate DNA synthesis and are cytotoxic for the proliferating cancer cells. However, therapeutic NAs in the form of 5'-triphosphates are considered too unstable as a drug form to be used directly in cancer chemotherapy. Based on preliminary data, the hypothesis being evaluated in this proposal is that encapsulation of 5'-triphosphates of antiproliferative NA in a submicron polymeric carrier with protective and targeting properties will result in a novel therapeutic form of the old drugs. The proposed formulation and delivery system is based on self-assembled polyionic complexes formed between nucleoside 5'-triphosphates and cationic carrier called 'Nanogel'. This carrier consists of a cross-linked network of cationic polyethylenimine and poly (ethylene glycol) or Poloxamer block copolymers. Nanogel loaded with triphosphate nucleotides in aqueous media forms small nanosized particles. Formulated into the particles for systemic administration, active triphosphates of NA can be conventionally stored in freeze-dried form and then readily dispersed before injection. Nanogel can protect triphosphate nucleotides in circulation against enzymatic degradation and drastically increase intracellular transport of anionic nucleotides, which otherwise is not effective. Specific aims of the proposal are to: (1) formulate polymer-nucleotide complexes with increased dispersion stability and enzymatic resistance, (2) Determine whether the polymer-nucleotide complexes can increase the cytotoxic effects of nucleotide analogues, and (3) Examine how the polymer-nucleotide complexes can enhance the systemic therapy of tumors in vivo. A panel of representative NA and cancer cell lines will be studied, and a murine Lewis lung carcinoma model will be used to verify obtained in vitro results. The long circulating polymer-nucleotide complexes can display better tumor accumulation because of the 'enhanced permeability and retention' effect. They can also be modified by vector ligands with affinity to surface receptors on actively proliferating cancer cells in order to enhance selective accumulation of the cytotoxic NA in tumors or metastatic nodes. Application of the drug forms may help to prevent many of the known chemotherapy side effects. Data accumulated in these studies can be directly used for design of better systemic formulations of cytotoxic nucleotide drugs.