Aurora A及haspin激酶在大腸癌細胞的組蛋白磷酸化作用及染色體運送複合體之角色

Abstract

組蛋白3的磷酸化作用以及由Aurora B、survivin、INCENP及borealin所組成的染色體運送複合體，在有絲分裂的紡錘絲及染色體的分離擔任重要的角色，Aurora A及haspin是調控有絲分裂進行的激酶，然而，Aurora A及haspin對於組蛋白3的磷酸化作用及染色體運送複合體的形成仍不清楚。大腸癌是世界上發生率及致死率最高的癌症之一。在本論文中，我們利用大腸癌細胞模式探討Aurora A及haspin對於組蛋白及染色體運送複合體的調控。MLN8237是一種Aurora A激酶的抑制劑，CHR6494是一種haspin的抑制劑，在大腸癌細胞中處理MLN8237及CHR6494皆能誘導中心體的擴增、紡錘絲的多極化及產生有絲分裂的風暴，有趣地，結合MLN8237及CHR6494能加強抗癌活性，包括細胞存活率的降低、多核細胞的增加、生長能力的抑制及細胞凋亡的誘導。同時，MLN8237及CHR6494能抑制組蛋白3的Thr-3及Ser-10磷酸化作用及降低Aurora B激酶及survivin的蛋白質表現，此外，轉殖survivin表現載體則會降低MLN8237或CHR6494所造成的細胞死亡。綜合以上結果，這篇論文是第一次發現Aurora A及haspin能共同調控組蛋白的磷酸化作用及染色體運送複合體的形成，結合Aurora A及haspin的標靶藥物可以發展作為治療大腸癌的新策略。

The phosphorylation of histone 3 and the chromosomal passenger complex (CPC), composed of Aurora B, survivin, INCENP and borealin, have been indicated important roles on the control of mitotic spindle and chromosomal segregation. Aurora A and haspin are mitotic kinases that can regulate mitotic progression. However, the roles of Aurora A and haspin on the phosphorylation of histone 3 and the formation of CPC remain largely unclear. Colorectal cancer (CRC) is one of the leading causes and mortality in the world. In this study, we investigated the roles of Aurora A and haspin on the regulation of histone 3 and CPC using CRC model. Both MLN8237 (an Aurora A inhibitor) and CHR6494 (a haspin inhibitor) induced centrosomal amplification, spindle multi-polarity and mitotic catastrophe in CRC cells. Interestingly, the combination of MLN8237 and CHR6494 enhanced the anticancer abilities, including the cell viability reduction, polyploidy cells increase, growth inhibition and apoptosis induction. Meantime, MLN8237 and CHR6494 inhibited the protein phosphorylations of histone 3 at Thr-3 and Ser-10 and the protein levels of Aurora B and survivin. Over-expression of survivin by pCT-GFP-sur8 vector could reduce the MLN8237 or CHR6494 induced cell death. This report demonstrates for the first time that Aurora A and haspin can co-regulate the phosphorylation of histone 3 and the formation of CPC. The combined targeting drugs on Aurora A and haspin may develop a novel strategy for CRC therapy.