DETECTION OF CD44 IMMUNOHISTOCHEMICAL EXPRESSION AND CLINICOPATHOLOGICAL CORRELATES IN COLORECTAL CARCINOMA

Abstract

Background: Cluster of differentiation 44 (CD44) is a non-kinase cell surface glycoprotein overexpressed in cancer stem cells (CSCs). Cells overexpressing CD44 exhibit several CSC traits, including self-renewal, epithelial–mesenchymal transition (EMT) capability, and resistance to chemo- and radiotherapy. CD44's role in maintaining CSC stemness and promoting tumour progression is primarily mediated through binding with its principal ligand, hyaluronan (HA), activating signalling pathways that drive cell proliferation, adhesion, migration, and invasion. The CD44 gene undergoes extensive alternative splicing generating standard (CD44s) and variant (CD44v) isoforms with distinct functional roles in colorectal carcinogenesis. Materials and Methods: The present cross-sectional study evaluated immunohistochemical CD44 expression in 50 surgically resected CRC specimens from SRM Medical College Hospital and Research Centre, Kattankulathur, Tamil Nadu. CD44 expression was scored as low (<10% positive tumour cells), moderate (10–50%), or strong (>50%). Results: Low expression was identified in 16% (n=8), moderate in 44% (n=22), and strong in 40% (n=20) of cases. Strong CD44 expression was significantly associated with lymphovascular invasion (LVI, p=0.043), TNM stage (p=0.019), and AJCC stage group (p=0.016). No significant association was observed with histological grade (p=0.756), perineural invasion (p=0.518), tumour budding (p=0.579), or tumour infiltrating lymphocytes (p=0.389). These results establish CD44 as a clinically relevant biomarker of tumour aggressiveness and an objective marker of invasion and staging progression in CRC.