Yang Nannan, Strøm Morten B, Mekonnen Seble M, Svendsen John S, Rekdal Oystein
Department of Biochemistry, Institute of Medical Biology, Faculty of Medicine, University of Tromsø, Norway.
J Pept Sci. 2004 Jan;10(1):37-46. doi: 10.1002/psc.470.
A number of shortened derivatives of the lactoferrin model peptide L12, PAWRKAFRWAKRMLKKAA, were designed in order to elucidate the structural basis for antitumour activity of lactoferrin derivatives. Three tumour cell lines were included in the study and toxicity determined by measuring lysis of human red blood cells and fibroblasts. The results demonstrated a strong correlation between antitumour activity and net positive charge, in which a net charge close to +7 was essential for a high antitumour activity. In order to increase the antitumour activity of the shortest peptide with a net charge less than +7, the hydrophobicity had to be increased by adding a bulky Trp residue. None of the peptides were haemolytic, but toxicity against fibroblasts was observed. However, modifications of the peptides had a higher effect on reducing fibroblast toxicity than antitumour activity and thereby resulted in peptides displaying an almost 7-fold selectivity for tumour cells compared with fibroblasts. The antimicrobial activity against the Gram-negative bacteria Escherichia coil and the Gram-positive bacteria Staphylococcus aureus was also included in order to compare the structural requirements for antitumour activity with those required for a high antimicrobial activity. The results showed that most of the peptides were highly active against both bacterial strains. Less modification by shortening the peptide sequences was tolerated for maintaining a high antitumour activity and selectivity compared with antimicrobial activity. The order of the amino acid residues and thereby the conformation of the peptides was highly essential for antitumour activity, whereas the antimicrobial activity was hardly influenced by changes in this parameter. Thus, in addition to a certain net positive charge and hydrophobicity, the ability to adopt an amphipathic conformation was a more critical structural parameter for antitumour activity than for antimicrobial activity, and implied that a higher flexibility or number of active conformations was tolerated for the peptides to exert a high antimicrobial activity.
为了阐明乳铁蛋白衍生物抗肿瘤活性的结构基础，设计了乳铁蛋白模型肽L12（PAWRKAFRWAKRMLKKAA）的多种缩短衍生物。该研究纳入了三种肿瘤细胞系，并通过测量人红细胞和成纤维细胞的裂解来确定毒性。结果表明，抗肿瘤活性与净正电荷之间存在很强的相关性，其中接近+7的净电荷对于高抗肿瘤活性至关重要。为了提高净电荷小于+7的最短肽的抗肿瘤活性，必须通过添加一个庞大的色氨酸残基来增加疏水性。这些肽均无溶血作用，但观察到对成纤维细胞有毒性。然而，肽的修饰对降低成纤维细胞毒性的影响比对抗肿瘤活性的影响更大，从而导致与成纤维细胞相比，肽对肿瘤细胞的选择性几乎提高了7倍。还包括了对革兰氏阴性菌大肠杆菌和革兰氏阳性菌金黄色葡萄球菌的抗菌活性，以便比较抗肿瘤活性与高抗菌活性所需的结构要求。结果表明，大多数肽对两种细菌菌株均具有高活性。与抗菌活性相比，为维持高抗肿瘤活性和选择性，通过缩短肽序列进行的修饰较少。氨基酸残基的顺序以及由此肽的构象对于抗肿瘤活性至关重要，而抗菌活性几乎不受该参数变化的影响。因此，除了一定的净正电荷和疏水性外，对于抗肿瘤活性而言，形成两亲性构象的能力是比抗菌活性更关键的结构参数，这意味着肽为发挥高抗菌活性可具有更高的灵活性或更多的活性构象。
