MEROCYANINE PHOTOPRODUCTS WITH ANTINEOPLASTIC ACTIVITY

Merocyanine 540 （MC540）是一种聚甲基染料，最初是作为感光乳剂的增感剂而开发的。我们和其他人随后表明，MC540也是一种有效的多用途制剂，可用于自体骨髓和外周血干细胞移植物的体外清除、被包膜病毒或原生动物寄生虫污染的血液成分的灭菌、外周血白血病细胞的鉴定、凋亡细胞的定量、跨膜电位变化的记录。以及发育调节膜成分的鉴定。W.H.H. Gunther与我们的实验室合作，合成了一组MC540的结构类似物，专门用于生物医学应用。其中一些类似物作为抗白血病和抗病毒药物的效力比MC540强几个数量级，但保留了母体化合物的大部分或所有理想特性。MC540的作用机制尚不清楚。对第二代merocyanines的了解就更少了，其抗肿瘤和抗病毒活性的基础也大大提高了。我们最近发现，MC540最有效的结构类似物产生一种光化合物，它与血清白蛋白（但不与其他血浆蛋白）共价结合，形成稳定的加合物，对白血病细胞比正常造血祖细胞更具细胞毒性。我们假设这些光产物在增强第二代merocyanine的抗肿瘤活性中起关键作用。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merocyanine （MC54）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，并研究它们差异细胞毒性的分子基础；3)确定细胞毒性加合物在merocyanine介导的光动力治疗中的作用。4)探索merocyanine衍生的光产物-白蛋白加合物在全身化疗中的潜在用途。本应用着重于光产物和白蛋白加合物产生的单一第二代merocyanine染料。然而，初步数据已经表明，其他merocyanine和非merocyanine光敏剂也会产生类似的光产物和细胞毒性加合物。因此，对MC54衍生的光产物和细胞毒性加合物的性质和作用机制的研究对光化学疗法和一般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.