Considering our hypothesis that the guanidinium moiety in the protein kinase type III inhibitor 1 interacts with a phosphate of ATP within the hinge region, the nature of the interactions established between a model isouronium and the phosphate groups of ATP was computationally analysed indicating that an isouronium derivative of 1 will interact in a similar manner with ATP. Thus, a number of compounds were prepared to assess the effect of the guanidinium/isouronium substitution on cancer cell growth; additionally, the molecular shortening and conformational change induced by replacing the di-substituted guanidine-linker of 1 by an amide was explored. The effect of these compounds on cell viability was tested in human leukaemia, breast cancer and cervical cancer cell lines and the resulting IC₅₀ values were compared with those of the lead compound 1. Replacement of the di-substituted guanidine-linker by an amide results in the loss of cytotoxicity; however, substitution of the mono-substituted guanidinium by an isouronium cation seems to be beneficial for cell growth inhibition. Additionally, the effect of these compounds on the MAPK/ERK pathway was studied by means of Western blotting and the results indicate that the isouronium derivative 2 decreases the levels of phosphorylated, and thus activated, ERK (pERK) both in leukaemia and breast cancer cells, whereas lead compound 1 only shows an effect on pERK levels in breast cancer cells. This confirms that both compounds could interfere with the MAPK/ERK pathway although other targets cannot be ruled out.

中文翻译：

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异脲铵/胍盐替代对一系列新型抗癌药物疗效的影响†

考虑到我们的假设，即蛋白激酶 III 型抑制剂1中的胍部分与铰链区内的 ATP 磷酸盐相互作用，计算分析了模型异脲鎓和 ATP 磷酸基团之间建立的相互作用的性质，表明异脲鎓衍生物1将与 ATP 以类似的方式相互作用。因此，制备了许多化合物来评估胍鎓/异脲取代对癌细胞生长的影响；此外，通过替换1的二取代胍-接头引起的分子缩短和构象变化通过酰胺进行了探索。在人类白血病、乳腺癌和宫颈癌细胞系中测试了这些化合物对细胞活力的影响，并将得到的 IC ₅₀值与先导化合物1的值进行了比较。用酰胺取代二取代的胍-接头导致细胞毒性丧失；然而，用异脲鎓阳离子取代单取代胍鎓似乎有利于细胞生长抑制。此外，通过蛋白质印迹研究了这些化合物对 MAPK/ERK 途径的影响，结果表明异脲衍生物2降低了白血病和乳腺癌细胞中磷酸化并因此激活的 ERK (pERK) 的水平, 而铅化合物图1仅显示了对乳腺癌细胞中pERK水平的影响。这证实了这两种化合物都可能干扰 MAPK/ERK 途径，尽管不能排除其他目标。