Use of confocal laser endomicroscopy with a fluorescently labeled fatty acid to diagnose colorectal neoplasms

Development of Dual-Scale Fluorescence Endoscopy for In Vivo Bacteria Imaging in an Orthotopic Mouse Colon Tumor Model

Colorectal cancer is a representative cancer where early diagnosis and proper treatment monitoring are important. Recently, cancer treatment using bacteria has actively progressed and has been successfully monitored using fluorescence imaging techniques. However, because subcutaneous tumor models are limited in reflecting the actual colorectal cancer situation, new imaging approaches are needed to observe cancers growing in the colon. The fluorescence endoscopic approach is an optimal monitoring modality to evaluate the therapeutic response of bacteria in orthotopic colon cancer. In this study, we developed dual-scaled fluorescence endoscopy (DSFE) by combining wide-field fluorescence endoscopy (WFE) and confocal fluorescence endomicroscopy (CFEM) and demonstrated its usefulness for evaluating bacterial therapy. Firstly, the endoscopic probe of DSFE was developed by integrating the CFEM probe into the guide sheath of WFE. Secondly, colorectal cancer tumor growth and tumors infiltrating the fluorescent bacteria were successfully monitored at the multi-scale using DSFE. Finally, the bacterial distribution of the tumor and organs were imaged and quantitatively analyzed using CFEM. DSFE successfully exhibited fluorescent bacterial signals in an orthotopic mouse colon tumor model. Thus, it can be concluded that the DSFE system is a promising modality to monitor bacterial therapy in vivo.

CD36 inhibits β-catenin/c-myc-mediated glycolysis through ubiquitination of GPC4 to repress colorectal tumorigenesis

The diverse expression pattern of CD36 reflects its multiple cellular functions. However, the roles of CD36 in colorectal cancer (CRC) remain unknown. Here, we discover that CD36 expression is progressively decreased from adenomas to carcinomas. CD36 loss predicts poor survival of CRC patients. In CRC cells, CD36 acts as a tumor suppressor and inhibits aerobic glycolysis in vitro and in vivo. Mechanically, CD36-Glypcian 4 (GPC4) interaction could promote the proteasome-dependent ubiquitination of GPC4, followed by inhibition of β-catenin/c-myc signaling and suppression of downstream glycolytic target genes GLUT1, HK2, PKM2 and LDHA. Moreover, disruption of CD36 in inflammation-induced CRC model as well as Apc^Min/+ mice model significantly increased colorectal tumorigenesis. Our results reveal a CD36-GPC4-β-catenin-c-myc signaling axis that regulates glycolysis in CRC development and may provide an intervention strategy for CRC prevention.