胃癌腹膜高转移细胞特异性结合噬菌体多肽的筛选及鉴定

目的寻找能够与胃癌腹膜高转移细胞GC9811-P特异性结合的噬菌体多肽,探索治疗胃癌腹膜转移的新方法。方法运用噬菌体呈现肽技术,先后用胃癌的腹膜高转移细胞系GC9811-P和其亲本细胞GC9811对噬菌体12肽库进行消减性的全细胞淘洗．经过3轮筛选,随机挑选40个噬菌体单克隆C1～G40。用ELISA法选取能够与GC9811-P特异性结合的单克隆。将选出的单克隆分别注入裸鼠腹腔,采用免疫组化法排除与正常组织亦高结合的阳性单克隆。对筛选出的噬菌体克隆进行DNA序列测定,并推导其外源性氨基酸序列,进行同源性分析。结果经过3轮淘洗,噬菌体克隆得到理想富集。C9、C18、C23、C29、C34和C37可与GC9811-P特异性结合,经免疫组化证实,这6个单克隆均不与裸鼠腹腔内正常组织结合。测序结果大致展示了两种外源性多肽,即TLNINRLIIPRT和SMSIxSPYIxxx。结论筛选出6个可与GC9811-P细胞特异性结合的噬菌体多肽;这两个肽序列能否阻断GC9811-P细胞向腹膜转移尚待进一步确定。

Screening and identification of phage-displayed polypeptides specifically binding to human gastric cancer with high metastatic potential to peritoneum

Objective By means of phage-display technique, to screen polypeptides that specifically bind to human gastric cancer with high metastatic potential to peritoneum. Methods Two human gastric cancer cell lines were used: GC9811-P with high metastatic potential to peritoneum and its wild type parental GC9811, to carry out subtractive screening with a phage display-12 peptide library. Results After three rounds of screening, 40 phage clones bond to GC9811-P cells were randomly selected. When injected into the peritoneal cavity of nude mice, 6 of the 40 clones did not bind to mouse peritoneum as examined by immunohistochemical staining. They were considered to be capable of binding specifically to GC9811-P cells. Sequence analysis revealed two different exogenous peptides: TLNINRLILPRT and SMSI_XSPYI_ XXX . Conclusion Two peptides have been obtained that specifically bind to a gastric cancer cell variant GC9811-P, which easily disseminates to the peritoneum. Whether or not they could block GC9811-P metastasis to peritoneum in vivo remains to be determined.