High GD2 expression defines breast cancer cells with enhanced invasiveness

Introduction: Breast cancer is the most frequently diagnosed cancer among women. Cancer stem cells (CSCs) are suggested to be responsible for tumor initiation, progression, metastasis, recurrence and drug resistance. This study was conducted to evaluate the clinical significance of GD2, a newly suggested CSC marker and two other traditional CSC markers, CD44 and CD24 in breast cancer patients. Material and methods: A total of 168 primary breast cancer tissues were evaluated in terms of GD2, CD44 and CD24 expression using tissue microarray. Then, the correlation of expression levels of these markers with patients' clinicopathological characteristics was assessed. Results: Higher GD2 expression was mainly found in patients with advanced histological grade (p = 0.02), presence of lymph node invasion (p = 0.04), larger size of tumors (p = 0.04) and older age (p = 0,04). Breast cancer samples with advanced histological grade also showed higher CD44 (p = 0.03) and CD24 expression (p = 0.05). A significant positive association was found between increased CD24 expression and lymph node involvement (p = 0.01). Furthermore, GD2-high/CD44-high/CD24-low phenotype was frequently seen in breast cancer samples with positive lymph node involvement (p = 0.05). Conclusion: In summary, increased expression of GD2 may define more aggressive tumor behavior in breast cancer. GD2 can well be considered as a diagnostic and prognostic marker in breast cancer.