Isolation of stool-derived mucus provides a high yield of colonocytes suitable for early detection of colorectal carcinoma.
BACKGROUND
Promising stool-based screening tests for colorectal carcinoma (CRC) rely on detection of exfoliated colonocytes or their contents. However, methods of colonocyte retrieval have not been studied systematically and current approaches are restricted by low yields. We examined colonocyte numbers in stool wash fractions and assessed the suitability of retrieved cells for immunocytochemistry for minichromosome maintenance protein 2 (MCM2), a marker of the proliferative deregulation that characterizes malignancy.


METHODS
Colonocyte numbers were accurately quantified in 129 wash fractions derived from 18 stools, comparing the mucus retained by a 125-microm filter (F fraction) with the fine and coarse content in the filtrate (S and P fractions, respectively). MCM2 immunocytochemistry was done on sections of fibrin clot containing filter-derived mucus, obtained from stools of eight independent subjects.


RESULTS
Total colonocyte yield in the F fraction (mean, 433.8 per 100 microL) was higher than in the S (140.3) and P (204.6) fractions (P = 0.004 and 0.03, respectively) due to increased numbers of morphologically abnormal cells, which predominantly represented malignant cells in samples from CRC patients. Several thousand abnormal cells could be obtained from stool-derived mucus in all CRC patients, an order of magnitude greater than numbers in subjects without CRC. Median MCM2 labeling index in abnormal cells was 50% (range, 30-60%) in CRC patients and 0% in subjects without CRC. Cells in clot sections were well preserved and not obscured by fecal debris.


CONCLUSIONS
Isolation of stool-derived mucus is technically straightforward and can improve the performance of protein-based and/or nucleic acid-based approaches to CRC screening.
White
Victoria
V
Medical Research Council Cancer Cell Unit, Hutchison/MRC Research Centre, Cambridge, UK.
Scarpini
Cinzia
C
Barbosa-Morais
Nuno L
NL
Ikelle
Emili
E
Carter
Stephanie
S
Laskey
Ronald A
RA
Miller
Richard
R
Coleman
Nicholas
N
D014408:Biomarkers, Tumor / Q000032:analysis*; D018797:Cell Cycle Proteins / Q000032:analysis; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D055088:Early Detection of Cancer; D005243:Feces / Q000737:chemistry / Q000166:cytology*; D005340:Fibrinogen / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007413:Intestinal Mucosa / Q000166:cytology*; D064111:Minichromosome Maintenance Complex Component 2; D009093:Mucus / Q000737:chemistry; D009687:Nuclear Proteins / Q000032:analysis; D018709:Statistics, Nonparametric
D014408:Biomarkers, Tumor; D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; D005340:Fibrinogen; C084859:MCM2 protein, human; D064111:Minichromosome Maintenance Complex Component 2