ABSTRACT
CDX2 (Caudal-type homeobox transcription factor 2) is a biomarker of differentiated colon enterocytes, whose expression has been associated with a favorable prognosis in colon cancer. The absence of CDX2 has been associated with an aggressive outcome, including an higher risk of relapse. CD44 (Cluster of Differentiation 44) is a transmembrane glycoprotein involved in cell growth, survival, differentiation and migration. It is considered a typical marker of cancer stem cells, with a role in colorectal cancer progression. The aim of this study was to analyze the expression of the stem cell marker CD44 and its relation to CDX2 expression in colorectal cancer.
To this end, 65 consecutive colorectal cancers were immunostained with anti-human CD44 Rabbit monoclonal antibody (clone SP37) and anti-human CDX2 Rabbit monoclonal antibody (clone EPR2764Y). 59 cases were positive for CDX2 and 47 were positive for CD44. Regarding cases positive for CDX2, 49 were positive for CD44. Our findings show the existence of a wide spectrum, ranging from cases CDX2-/CD44- to tumors expressing both markers. Multiple further combinations of the two markers were also found. CD44 immunoreactive tumors showed an high stage at diagnosis, suggesting a possible association of CD44 expression with an aggressive outcome of colorectal cancer.

IMPACT STATEMENT
The expression of CD44 in CDX-2 negative tumors could indicate a possible target-therapy targeted to CD44.