重組第一類轉形生長因子與篦麻毒素A融合蛋白質對人類癌症細胞之生長抑制效應

Abstract

癌症細胞尤其是肺癌細胞大多表現高密度之上皮生長因子受體(epiderrnal growth factor receptor;EGFR)，而腫瘤細胞本身會分泌第一類轉型生長因子(transforrning growth factor-α; TGF-α)，當TGF-α與細胞本身或鄰近的EGFR緊密結合之後，造成受體自體磷酸化之後引發細胞內連續訊號傳遞的發生，而促使細胞的增生。若將TGF-α與蓖麻毒素A(ricin A)結合形成重組融合蛋白，由EGFR選擇性結合，進入細胞質後，讓所連結的蓖麻毒素A進入核糖體，使細胞蛋白質轉譯功能降低，故能抑制腫瘤細胞的生長。本文以基因工程方式製作大量重組蛋白—TGF-α-蓖麻毒素A。 實驗首先將TGF-α與蓖麻毒素A的基因選殖出來，進行DNA重組，經限制酵素切割及核酸定序確認有正確的序列之後，植入大腸桿菌，誘導大腸桿菌表現該重組基因後分泌融合蛋白到培養液中，將重組蛋白萃取純化後，用於細胞培養。使用人類上皮癌細胞A431細胞株，以分別測試重組融合蛋白與蓖麻毒素A對癌細胞的抑制效應。

Human cancer cells express epidermal growth factor receptors (EGFR) and natural ligand-transforming growth factor-a (TGF-α). In this work, recombinant construct comprises of TGF-α and ricin A was made in a hope that the expressed recombinant protein undergoes endocytosis and is expected to inhibit proliferation selectively in cells over-expressing EGFR. The recombinant construct was established in this work and the expressed protein identified. The preliminary result showed that the expressed protein inhibited human epithelial carcinoma cell line, A431, also known overexpressing EGFR's.