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

Abstract

Background & Aims 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 pre-cancerous lesions. We aim 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 demonstrated specific binding to human CRC cells. We collected in vivo near-infrared fluorescence images endoscopically in the CPC;Apc mouse that develops colonic adenomas spontaneously. With immunofluorescence, we validated specific peptide binding to adenomas from 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 demonstrated specific binding of RTSPSSR to claudin-1 in knockdown and competition studies, and measured an affinity of 42 nM and 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 to normal with in vivo images. On immunofluorescence, we found significantly greater intensity (mean±std) for human adenomas (25.5±14.0) versus normal (9.1±6.0) and hyperplastic polyps (3.1±3.7), P=10−5 and 8×10−12, respectively, and for sessile serrated adenomas (20.1±13.3) versus normal and hyperplastic polyps, P=0.02 and 3×10−7, respectively. Conclusions Claudin-1 is overexpressed in pre-malignant colonic lesions, and can be detected endoscopically in vivo with a near-infrared labeled peptide.

Tight junction proteins in gastrointestinal and liver disease

“…A recent study has shown that serum levels of CLDN1 and CLDN7 may be a useful tool in the differential diagnosis of CRC 163. Furthermore, a progressive increase in CLDN1 expression in colon cancer and the recent findings that infrared imaging using CLDN1-targeted conjugated peptide can enhance the ability of conventional colonoscopy for detecting human colonic adenomas strongly supports the potential impact of CLDN1 as a biomarker 164. CRC has been found to arise from missed polypoid and flat precancerous lesions which are more difficult to visualise by colonoscopy and the new CLDN1 targeted fluorescent peptides may be used to improve screening of high-risk patients with multiple polyps, IBD, Lynch syndrome or a family history of CRC.…”

Introducing fluorescence guided surgery into orthopedic oncology: A systematic review of candidate protein targets for Ewing sarcoma

“…In a similar study Machado et al found a strong positive staining of claudin‐1 in 285 of 415 tissue samples (76%). Rabinsky et al performed a study on real‐time NIR fluorescence endoscopic imaging of mice bearing human colonic adenomas. They used a phage display‐derived peptide CLDN‐1(53‐80) labeled with near‐infrared dye Cy5.5 at the C‐terminus.…”

A cCPE‐based xenon biosensor for magnetic resonance imaging of claudin‐expressing cells

“…In addition, phage display yielded a broad specific claudin binder (cCPES305P/S307R/S313H) . The latter also interacts with Cldn1, a claudin that was recently targeted by fluorophore‐labeled Cldn1‐mimetic binding peptide for endoscopic detection of Cldn1 overexpression in mice, a hallmark of colon cancer . However, the signal‐to‐noise ratio was quite low, which might be improved by use of a Cldn1‐binding cCPE‐variant xenon biosensor.…”