Elucidation of the roles of Pim-1 induced under hypoxia in pancreatic cancer and its application to the cancer therapy

在本研究中，我们基于Pim-1蛋白在缺氧条件下表达增强的发现，研究抑制Pim-1活性是否能有效治疗胰腺癌。根据已有报道表明，由11个精氨酸组成的多肽融合蛋白可以通过细胞质膜，我们构建了一个编码血小板生成素显性阴性Pim-1蛋白11个精氨酸信号序列的表达载体。PCI-43。细胞，一种胰腺癌细胞系，皮下接种到SCID小鼠的背部。然后在小鼠股肌内注射载体。注射PIM-1显性阴性表达载体21天后，各组小鼠肿瘤消失，空表达载体组肿瘤生长。这些结果提示，利用Pim-1显性阴性表达载体进行基因治疗可能对肿瘤有效。然而，在临床试验中，应减少注射表达载体的剂量。我们寻找能抑制Pim-1功能的小化合物库。我们发现了14个小的化合物，它们抑制PIM-1的磷酸化活性超过40%。我们现在正计划研究这些化合物的体内抗肿瘤作用。

In this study, we examined whether the inhibition of Pim-1 activity, is effective treatment pancreatic cancer, based on the findings that Pim-1 protein expression enhanced under hypoxic conditions. According to the previous reports demonstrating that the protein fused to polypeptides composed of eleven arginine can pass through the cytoplasmic membrane, we constructed an expression vector encoding 11 arginine-signal sequence of Thrombopoietin-dominant negative Pim-1 protein. PCI-43. cells, a pancreatic cancer cell line, were inoculated subcutaneously into the back of SCID mice. Then the mice were treated with the injection of the vectors into the femoral muscle. At 21 days after the treatment, the tumors in the mice treated with the injection of dominant negative PIM-1 expression vector disappeared, whereas the tumors in those treated with empty vector grew. These results suggest that the gene therapy using dominant negative Pim-1 expression vector may be effective for the cancer. However, the doses of expression vector to inject should be reduced for clinical trials. We sought small chemical compound library for the chemical compounds which could suppress the function of Pim-1. We found fourteen small chemical compounds which suppressed the phosphorylation activity of PIM-1 by more than 40 %. We are now planning to examine the in vivo anti-tumor effects of those compounds.