The CD44+/CD24- phenotype is enriched in basal-like breast tumors

Area of Science:

• Oncology
• Cancer Biology
• Immunohistochemistry

Background:

• Human breast tumors exhibit significant cellular heterogeneity.
• The CD44+/CD24- cell phenotype is associated with tumor-initiating, stem-like, and invasive properties.
• Understanding the clinical implications of CD44+/CD24- cells across breast cancer subtypes is crucial.

Purpose of the Study:

• To investigate the prevalence of different CD44/CD24 cell phenotypes within distinct breast cancer subtypes.
• To explore the association between CD44+/CD24- cell presence and specific breast cancer molecular and hereditary characteristics.

Main Methods:

• Utilized double-staining immunohistochemistry to quantify CD44 and CD24 expression in 240 human breast tumors.
• Analyzed gene expression data for a subset of the tumor cohort.
• Correlated CD44/CD24 phenotypes with existing tumor marker and clinical data.

Main Results:

• Observed substantial heterogeneity in CD44 and CD24 expression both between and within tumors.
• CD44+/CD24- cells were detected in 31% of tumors, with highest prevalence in basal-like and BRCA1 hereditary breast cancers (94%).
• HER2+ tumors predominantly showed a CD24+ status, with scarce CD44+/CD24- cells. A CD44+/CD24- gene expression signature was identified.

Conclusions:

• Established an association between basal-like and BRCA1 hereditary breast cancers and the presence of CD44+/CD24- cells.
• Highlighted that not all basal-like tumors and few HER2+ tumors contain CD44+/CD24- cells.
• Emphasized the potential for other breast cancer stem cell markers to be identified.