Significance of CD133 Expression in Invasive Ductal Carcinoma of the Breast

Introduction:

Breast carcinoma is the most frequent malignant tumor in women worldwide comprising 30% on average of all cancers and the most likely cause of cancer-related deaths in women worldwide. In Egypt, according to the official statistics of the National Cancer Institute, Cairo University, breast carcinoma is the most prevalent cancer among women representing 35.1% of total cancer cases.

Breast carcinoma is currently regarded as a heterogeneous group of tumors with diverse morphology, behavior, outcome and response to therapy. In spite of advances in diagnosis and treatment of breast carcinoma, the clinical outcome remains unsatisfactory due to recurrence, metastasis or chemotherapy-resistance.

Cancer stem cells (CSCs) are recognized as a subpopulation of cancer cells that show the characteristics of normal stem cells. They are believed to possess the capacity to self-renewal and are responsible for tumor formation and progression. CSCs also promote tumor cell heterogeneity and metastasis. In addition, CSCs are thought to be more resistant to chemotherapy and radiotherapy. Given the significance of CSCs in tumor development, the identification and characterization of CSCs could lead to the development of directed therapies against these aggressive cells, hence more effective treatments for cancer.

Over recent years, CSCs have been described in different types of cancers including breast cancer. In the mammary gland, the microenvironment provides clues to control the behavior of epithelial stem and progenitor cells. Breast cancer stem cells (BCSCs) subpopulation was shown to express higher level of pro-invasive genes and had highly invasive properties.