黏蛋白1多肽通过small MUC1蛋白抑制肿瘤细胞生长

MUC1 peptide inhibits tumor cell proliferation by binding small MUC1 protein

目的:探讨黏蛋白1(mucin1,MUC1)串联重复序列多肽(简称黏蛋白1多肽,MUC1多肽)对肿瘤细胞生长抑制的作用机制。方法:MUC1多肽与多种肿瘤细胞Jurkat、Raji、U937、MCF-7、SMMC7721及活化的T细胞、小鼠巨噬细胞RAW264.7共同培养,观察MUC1多肽对上述细胞生长的影响;建立BABL/c小鼠Jurkat细胞皮下移植瘤动物模型,应用MUC1多肽进行治疗;采用GST免疫沉降实验鉴定与MUC1多肽结合的肿瘤细胞表面蛋白。结果:MUC1多肽对Jurkat、Raji、U937、MCF-7和SMMC7721细胞的生长均有抑制作用,对活化的T细胞和小鼠RAW264.7细胞生长无明显抑制作用。MUC1多肽对BABL/c小鼠皮下Jurkat细胞移植瘤的生长均有明显抑制作用(P<0.05)。GST免疫沉降实验显示,Jurkat和MCF-7细胞裂解上清中与MUC1多肽结合的蛋白可与两种抗MUC1串联重复序列抗体(GP1.4和HMPV)及抗胞内段抗体(Ab5)发生反应,相对分子质量大约115000,提示可能是MUC1新的同种型,命名为smallMUC1(sMUC1)。结论:MUC1多肽可通过与肿瘤细胞表面smallMUC1蛋白的相互作用向细胞传导生长抑制信号。

Objective：To investigate the inhibitory mechanism of mucin 1 tandem repeats peptide （MUC1 peptide） against the proliferation of tumor cells. Methods： Jurkat, Raji, U937, MCF7, SMMC7721, activated T and RAW264.7 cells were cocultured with MUC1 peptide; the inhibitory effects of MUC1 peptide on these cells were observed. Jurkat cellinoculated BABL/c mouse model was established by s.c. injection of Jurkat cells, and then the tumorbearing mice were treated with MUC1 peptide. The protein interacting with MUC1 peptide was identified by GST pulldown assay. Results： MUC1 peptide inhibited the proliferation of Jurkat, Raji, U937, MCF7 and SMMC7721 cells, but had no measurable inhibitory effect on activated T cells and RAW264.7 cells. MUC1 peptide significantly inhibited the growth of implanted Jurkat tumors in BABL/c mice （P〈0.05）. The protein interacting with MUC1 peptide in the lysates of Jurkat and MCF7 cells was confirmed by GST pulldown assay, with its molecular weight being approximately 115 000. The protein could bind specifically to antiMUC1 tandem repeat antibodies （GP1.4 and HMPV） and antiMUC1 cytoplasmic domain antibody （Ab5）, indicating it might be a novel isotype of MUC1, and it was named small MUC1 （sMUC1）. Conclusion： MUC1 peptide can transduce growth inhibitory signal by interacting with small MUC1 on the surface of tumor cells.