Rebacz Blanka, Larsen Thomas O, Clausen Mads H, Rønnest Mads H, Löffler Harald, Ho Anthony D, Krämer Alwin
Clinical Cooperation Unit for Molecular Hematology/Oncology, German Cancer Research Center (DKFZ) and Department of Internal Medicine V, University of Heidelberg, Heidelberg, Germany.
Cancer Res. 2007 Jul 1;67(13):6342-50. doi: 10.1158/0008-5472.CAN-07-0663.
A major drawback of cancer chemotherapy is the lack of tumor-specific targets which would allow for the selective eradication of malignant cells without affecting healthy tissues. In contrast with normal cells, most tumor cells contain multiple centrosomes, associated with the formation of multipolar mitotic spindles and chromosome segregation defects. Many tumor cells regain mitotic stability after clonal selection by the coalescence of multiple centrosomes into two functional spindle poles. To overcome the limitations of current cancer treatments, we have developed a cell-based screening strategy to identify small molecules that inhibit centrosomal clustering and thus force tumor cells with supernumerary centrosomes to undergo multipolar mitoses, and subsequently, apoptosis. Using a chemotaxonomic selection of fungi from a large culture collection, a relatively small but diverse natural product extract library was generated. Screening of this compound library led to the identification of griseofulvin, which induced multipolar spindles by inhibition of centrosome coalescence, mitotic arrest, and subsequent cell death in tumor cell lines but not in diploid fibroblasts and keratinocytes with a normal centrosome content. The inhibition of centrosome clustering by griseofulvin was not restricted to mitotic cells but did occur during interphase as well. Whereas the formation of multipolar spindles was dynein-independent, depolymerization of interphase microtubules seemed to be mechanistically involved in centrosomal declustering. In summary, by taking advantage of the tumor-specific phenotype of centrosomal clustering, we have developed a screening strategy that might lead to the identification of drugs which selectively target tumor cells and spare healthy tissues.
癌症化疗的一个主要缺点是缺乏肿瘤特异性靶点，这些靶点能够在不影响健康组织的情况下选择性地根除恶性细胞。与正常细胞相比，大多数肿瘤细胞含有多个中心体，这与多极有丝分裂纺锤体的形成和染色体分离缺陷有关。许多肿瘤细胞在通过多个中心体合并为两个功能性纺锤极进行克隆选择后恢复有丝分裂稳定性。为了克服当前癌症治疗的局限性，我们开发了一种基于细胞的筛选策略，以鉴定能够抑制中心体聚集的小分子，从而迫使具有多余中心体的肿瘤细胞进行多极有丝分裂，随后发生凋亡。通过从大量培养物收集中进行真菌的化学分类学选择，生成了一个相对较小但多样的天然产物提取物库。对该化合物库的筛选导致了灰黄霉素的鉴定，它通过抑制中心体合并、有丝分裂停滞以及随后在肿瘤细胞系中诱导多极纺锤体形成和细胞死亡，但在具有正常中心体含量的二倍体成纤维细胞和角质形成细胞中则不会。灰黄霉素对中心体聚集的抑制不仅限于有丝分裂细胞，在间期也会发生。虽然多极纺锤体的形成不依赖动力蛋白，但间期微管的解聚似乎在机制上参与了中心体解聚。总之，通过利用中心体聚集的肿瘤特异性表型，我们开发了一种筛选策略，该策略可能会导致鉴定出选择性靶向肿瘤细胞并使健康组织免受影响的药物。
