Overexpressed Claudin-1 Can Be Visualized Endoscopically in Colonic Adenomas In Vivo

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• 作者：Emily F. Rabinsky¹ ; Bishnu P. Joshi¹ ; Asha Pant¹ ; Juan Zhou¹ ; Xiyu Duan² ; Arlene Smith¹ ; Rork Kuick³ ; Shuling Fan⁴ ; Asma Nusrat⁴ ; Scott R. Owens⁴ ; Henry D. Appelman⁴ ; Thomas D. Wang¹ ; ² ; ⁵ ; ^{thomaswa@umich.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Colon Cancer ; Early Detection ; Molecular Imaging
• 刊名：CMGH Cellular and Molecular Gastroenterology and Hepatology
• 出版年：2016
• 出版时间：February 2016
• 年：2016
• 卷：2
• 期：2
• 页码：222-237
• 全文大小：5839 K

文摘

Conventional white-light colonoscopy aims to reduce the incidence and mortality of colorectal cancer (CRC). CRC has been found to arise from missed polypoid and flat precancerous lesions. We aimed to establish proof-of-concept for real-time endoscopic imaging of colonic adenomas using a near-infrared peptide that is specific for claudin-1.

Methods

We used gene expression profiles to identify claudin-1 as a promising early CRC target, and performed phage display against the extracellular loop of claudin-1 (amino acids 53–80) to identify the peptide RTSPSSR. With a Cy5.5 label, we characterized binding parameters and showed specific binding to human CRC cells. We collected in vivo near-infrared fluorescence images endoscopically in the CPC;Apc mouse, which develops colonic adenomas spontaneously. With immunofluorescence, we validated specific peptide binding to adenomas from the proximal human colon.

Results

We found a 2.5-fold increase in gene expression for claudin-1 in human colonic adenomas compared with normal. We showed specific binding of RTSPSSR to claudin-1 in knockdown and competition studies, and measured an affinity of 42 nmol/L and a time constant of 1.2 minutes to SW620 cells. In the mouse, we found a significantly higher target-to-background ratio for both polypoid and flat adenomas compared with normal by in vivo images. On immunofluorescence, we found significantly greater intensity for human adenomas (mean ± SD, 25.5 ± 14.0) vs normal (mean ± SD, 9.1 ± 6.0) and hyperplastic polyps (mean ± SD, 3.1 ± 3.7; P = 10^-5 and 8 × 10^-12, respectively), and for sessile serrated adenomas (mean ± SD, 20.1 ± 13.3) vs normal and hyperplastic polyps (P = .02 and 3 × 10^-7, respectively).

Conclusions

Claudin-1 is overexpressed in premalignant colonic lesions, and can be detected endoscopically in vivo with a near-infrared, labeled peptide.