Targeted Confocal Laser Endomicroscopy (CLE) for the Assessment of Putative Cancer Stem Cell Markers in Colorectal cancer - A Pilot Study

Abstract

Background: Colorectal cancer is one of the most common diagnosed malignancies in the world. Successful treatment is related not only to the resection of the main tumor mass but also to the destruction of colorectal cancer cells which are highly resistant to chemoradiotherapy, with unlimited self-renewal and tumor-initiating capacities. CD44 is an important adhesion molecule and one of the proposed stem cell markers in colorectal cancer known to be involved in cell growth, differentiation and survival. Aim: We conducted a prospective study with the aim of evaluating the feasibility of confocal laser endomicroscopy (CLE) to identify and assess the distribution patterns of CD44, taking into consideration further directions related to the role that CD44 might play in improving tumor assessment, individualized cancer therapy and better tumor control. Methods: Fresh biopsies from tumor and normal tissue were collected from 13 patients previously diagnosed with primary colorectal adenocarcinoma during routine colonoscopy procedures, with pathology confirmation. A series of optical slices were immediately collected after staining each sample with fluorescent anti-CD44 antibodies, using a dedicated CLE system and analyzed using Image J. The images with the most pronounced fluorescent signal and a clear display of the tissue and stem cells were selected. Results: Our study included 13 patients, with an average age of 60±14,2 years. A number of 537 slides were analyzed, stacked and the most relevant were selected for cell counting. Standard biopsy sections from normal mucosa showed a well defined layout of the mucosal structures while this characteristic was lost among the tumor samples. CLE evaluation of the selected images revealed 34,92±16 cells/slide for the tumor tissue and 22,77±11,65 cells/slide for the normal tissue (p=0,037). Conclusion(s):Targeted CLE based on fluorescent anti-CD44 antibodies was found to be feasible for real-time imaging and evaluation of CD44 positive cells in CRC patients, although further extended studies are required. Core TIP: An increasing amount of data regarding the immunohistochemical or genetic assessment of putative cancer stem cell in colorectal cancer is available, stating their importance in tumor development, metastasis or tumor relapse. In our study we evaluated one of the main cancer stem cell biomarkers that literature is proposing, CD44. To our knowledge, this is the first time when a state-of-the-art technique such as confocal laser endomicroscopy was used to describe the expression patterns of CD44 in fresh human Gastro Unit, Division of Endoscopy, Copenhagen University Hospital Herlev, Denmark Received: 20.11.2017 Accepted: 12.12.2017 colorectal cancer specimens. Our results suggest that targeted CLE is feasible for real-time imaging and evaluation of CD44 positive cells in CRC patients.