PCNA在真核細胞中是一個DNA複製與損傷修補所必須的重要蛋白，主要負責維持染色 體的正確性與完整性。經由我們最近的研究發現，與染色質結合的PCNA蛋白在其?氨 酸211(Y211)的位置能被磷酸化，此磷酸化的PCNA蛋白能強化其蛋白在染色質上的穩定 性與相關功能。除此之外，我們也發現?Y211磷酸化的PCNA蛋白增加同時也會伴隨著 細胞增生明顯的增加。而且研究發現Y211磷酸化的PCNA蛋白與乳癌病患的存活?關係 較全部PCNA蛋白還要顯著。雖然磷酸化的PCNA蛋白大?表現在癌細胞中，且磷酸化 的PCNA蛋白能強化其蛋白在染色質上的穩定性，然而它的磷酸化在腫瘤發展過程中的 角色還並?完全清楚。所以在這次我們所提的計畫中，我們首先是要繼續探討與Y211 磷酸化PCNA蛋白所結合的交互作用蛋白在腫瘤發展過程中的角色。此外，除?Y211在 PCNA上的磷酸化之外，我們將進一步研究如何調控另一個新穎且能被UV誘導的Y114 PCNA磷酸化與其在癌細胞UV照射下的角色。最後，根據我們先前的研究發現，磷酸化 的PCNA蛋白能強化其蛋白在染色質上的穩定性且可能在腫瘤發展過程中扮演重要角 色。因此，我們將試著運用干擾性的PCNA胜?藉由影響PCNA的磷酸化進而抑制癌細 胞生長?發展新穎且有效的癌症治?方法。因此本計畫的三個目標如下: 第一，探討 Y211磷酸化PCNA的結合蛋白在腫瘤發展過程中的角色。第二，研究癌細胞如何調控UV 誘導的Y114 PCNA磷酸化與其在UV照射下的角色。第三，運用干擾性的PCNA胜??發 展新穎的癌症治?方法。這個計畫可以讓我們??解調控磷酸化PCNA在腫瘤發展過程 中的訊息網?。因此完成此計畫?僅可以提供?一個很好的機會?進一步?解磷酸化 PCNA調控癌細胞增生問題也有助於未?成功發展出的新穎癌症治?方法。
The proliferating cell nuclear antigen (PCNA) is a critical processivity protein acting as a DNA clamp for DNA replication and damage repair to maintain genomic integrity in eukaryotic cells. We previously demonstrated that the chromatin-bound PCNA protein is able to be phosphorylated on tyrosine 211 (Y211) in cancer cells, which is required for its stabilization and associated functions. Consistently, increased PCNA Y211 phosphorylation coincides with pronounced cell proliferation and is better correlated with poor survival of breast cancer patients in tumors than the total PCNA level. The PCNA has been shown that is tyrosine phosphorylated in cancer cells and especially required for its stabilization. However, the role of tyrosine phosphorylated PCNA in tumor progression remains elusive. In this current proposal, we continue to elucidate the roles of the phospho-Y211 PCNA and its associated proteins that may be involved in tumor progression. In addition to phospho-Y211 PCNA, we will extend our study to investigate the regulation of UV-induced phospho-Y114 PCNA, another novel tyrosine phosphorylation site in PCNA of cancer cells, and its role in UV irradiation. From our studies, the tyrosine phosphorylated PCNA required for its stabilization and may contribute to tumor progression in cancer cells, we will plan to develop an anti-cancer therapy by engineering PCNA-derived interference peptides to disrupt PCNA functions may further enhance tumor-cell killing. Three Specific Aims are proposed: 1. To characterize the roles of the phospho-Y211 PCNA-associated proteins in tumor progression; 2. To investigate the regulation of phospho-Y114 PCNA and their role in UV irradiation; and 3. To develop a novel anti-cancer therapy through PCNA-derived interference peptides. The proposed work will greatly extend our knowledge on the signaling network regulating tyrosine phosphorylated PCNA functions that may contribute to tumor progression. Success of outcome will not only allow us to further understand underlying mechanisms of cancer cell proliferation regulated by tyrosine phosphorylated PCNA, but eventually to design an effective therapeutic intervention for cancer treatment.
