MEROCYANINE PHOTOPRODUCTS WITH ANTINEOPLASTIC ACTIVITY

Mercury 540（MC 540）是一种多甲川染料，最初是作为感光乳剂的增感剂开发的。我们和其他人随后已经表明，MC 540也是一种有效和通用的试剂，用于自体骨髓和外周血干细胞移植物的体外净化，被包膜病毒或原生动物寄生虫污染的血液成分的灭菌，外周血中白血病细胞的鉴定，凋亡细胞的定量，跨膜电位变化的记录，和鉴定发育调节的膜成分。与我们的实验室合作，W.H.H. Gunther合成了一组专门用于生物医学应用的MC 540结构类似物。这些类似物中的一些作为抗白血病剂和抗病毒剂比MC 540强几个数量级，但保留了母体化合物的大多数或所有期望的性质。MC 540的作用机制尚不清楚。甚至对第二代部花青的了解更少，并且对显着提高抗病毒和抗病毒活性的基础知之甚少。我们最近发现，MC 540的最有效的结构类似物产生共价结合血清白蛋白（但不结合其他血浆蛋白）的光化合物，形成稳定的加合物，比正常的造血祖细胞更具细胞毒性的白血病细胞。我们推测，这些光产物在增强第二代部花青的生物活性中起着至关重要的作用。为了验证我们的假设，我们提出1）鉴定由我们最有效的第二代部花青（MC 54）之一形成的光产物和细胞毒性白蛋白加合物的结构，2）分析光产物-白蛋白加合物的结合、细胞摄取和亚细胞定位，并研究其差异细胞毒性的分子基础，3）确定细胞毒性加合物在部花青介导的光动力学治疗中的作用，以及4）探索部花青衍生的光产物-白蛋白加合物用于全身化疗的潜在效用。本申请集中于由单个第二代mercury染料产生的光产物和白蛋白加合物。然而，初步数据已经表明，类似的光产物和细胞毒性加合物也产生其他汞和非汞光敏剂。因此，对MC 54衍生的光产物和细胞毒性加合物的性质和作用机制的拟议调查对一般光化学疗法和化学疗法的主要部分具有广泛的理论和实践意义。

Merocyanine 540 (MC540) is a polymethine dye that was originally developed as a sensitizing agent for photographic emulsions. We and others have subsequently shown that MC540 is also an effective and versatile agent for the extracorporal purging of autologous bone marrow and peripheral blood stem cell grafts, the sterilization of blood components contaminated with enveloped viruses or protozoan parasites, the identification of leukemia cells in peripheral blood, the quantitation of apoptotic cells, the recording of transmembrane potential changes, and the identification of developmentally regulated membrane constituents. In collaboration with our laboratory, W.H.H. Gunther has synthesized a panel of structural analogues of MC540 specifically designed for biomedical applications. Some of these analogues are orders of magnitude more potent than MC540 as anti- leukemic and antiviral agents but retain most or all desirable properties of the parent compound. The mechanism of action of MC540 is poorly understood. Even less is known about second generation merocyanines and the basis of the dramatically improve antineoplastic and anti-viral activity. We recently discovered that the most potent structural analogues of MC540 generate a photocompound that covalently binds to serum albumin (but not to other plasma proteins) to form stable adducts that are more cytotoxic leukemia cells than to normal hematopoietic progenitor cells. We hypothesize that these photoproducts play a crucial role in the enhanced antineoplastic activity of second generation merocyanines. To test our hypotheses we propose 1) to identify the structures of the photoproduct and cytotoxic albumin adducts formed by one of our most potent second generation merocyanines (MC54), 2) to analyze the binding, cellular uptake, and subcellular localization of photoproduct-albumin adducts and to investigate the molecular basis of their differential cytotoxicity, 3) to define the role of cytotoxic adducts in merocyanine-mediated photodynamic therapy, and 4) to explore the potential utility of merocyanine-derived photoproduct-albumin adducts for systemic chemotherapy. This application focuses on photoproducts and albumin adducts generated by a single second generation merocyanine dye. However, preliminary data already indicate that similar photoproducts and cytotoxic adducts are also generated by other merocyanine and non-merocyanine photosensitizers. The proposed investigations into the nature and mechanism of action of MC54- derived photoproducts and cytotoxic adducts thus have broad theoretical and practical implications for major segments of photochemotherapy and chemotherapy in general.