Folate Receptor Is a Marker of Colorectal Adenoma in a Prospective Cohort of Matched Colorectal Adenoma and Normal Colon Organoids

Introduction: Colorectal cancer (CRC) prevention with colonoscopy has been shown to reduce cancer mortality through the detection of precancerous polyps, termed adenomas. However, more than half of CRCs diagnosed after baseline colonoscopy result from lesions that are missed during screening colonoscopy. Therefore, novel strategies for identifying precancerous lesions during screening colonoscopy are urgently needed. Recent evidence suggests that the folate receptor is overexpressed in most epithelial cancers. Our published studies in a mouse model of colorectal adenoma show that folate-conjugated nanoparticles preferentially bind to the mucosal surface of adenoma, but not to normal colon. However, the expression of folate receptor has not been studied in human colorectal adenomas. Methods: Polyp-derived and matched distal normal colon large biopsies were obtained from 24 patients who were referred to Duke University Hospital for resection of large ( >2cm) polyps, and in vitro three-dimensional cultures (i.e., organoids) were generated. The differential expression of the folate receptor (FOLR1) gene was evaluated in normal and Polyp-derived organoids derived from 5 randomly selected subjects. Localization of FOLR1 protein was assessed by immunocytochemistry of Polyp-derived organoids and immunohistochemistry staining of resected polyp tissue histology sections. Results: Polyps were identified on colonoscopy as 54% lateral spreading and 46% sessile. Polyps were diagnosed on pathology as 59% tubular adenoma, 33% tubulovillous adenoma, 4% serrated, and 4% adenocarcinoma. We successfully derived, passaged, and stored organoids from 100% (24/24) from polyp and normal colon biopsies. FOLR1 gene expression was significantly upregulated in Polyp-derived organoids compared to normal organoids (P=0.04) (Figure 1, Panel 1). IHC staining shows that FOLR1 is strongly expressed in the clinically relevant apical side of resected polyp tissues (Figure 1, Panel 2). We also found strong expression of FOLR1 on the outer apical membrane of Polyp-derived organoids (Figure 1, Panel 3). Conclusion: Our results demonstrate that organoids can be generated from matched polyp and normal colon biopsies with a high success rate. We find that folate receptor is significantly upregulated in adenoma organoids compared to normal colon organoids. Thus, our matched polyp and normal colon organoid biobank is an ideal resource for testing novel technologies such as folate-conjugated nanoparticles for identification of precancerous adenomas during colonoscopy.Figure 1.: Panel 1) FOLR1 gene expression is significantly upregulated in Polyp-derived organoids vs normal colon organoids. Panel 2) Immunohistochemistry staining shows FOLR1 protein expression at the apical side of the epithelium of resected polyp tissue. Panel 3) Immunocytochemistry staining demonstrates FOLR1 protein expression (red) at the outer membrane of Polyp-derived organoids. Nuclei were stained with DAPI (blue).