Impact of neoadjuvant therapy on cancer stem cell gene expression and miRNA profiles in breast cancer patients: Implications for therapy resistance and survival, a cross-sectional observational study

Breast cancer is one of the most common cancers in women worldwide. Several therapy modalities have been created recently; however, resistance to therapy is a major issue. Cancer stem cell functions and regulations are important in tumor progression, invasion, metastasis, and therapy resistance. The expression levels of cancer stem cell genes CD44, CD24, and related miRNAs miR590-3p, miR599, and miR399-3p were aimed to be investigated before and after neoadjuvant therapy in breast cancer patients in this cross-sectional observational study. This study included 80 samples from 40 female patients. The expression of CD44 and CD24 genes and miR590-3p, miR599, and miR399-3p was analyzed by qPCR in pre- and posttreatment biopsies from breast carcinoma patients. Correlations between expression levels and other pathologic parameters, including molecular subtypes, grade, stage, metastasis, recurrence, pathologic response to therapy, and disease-free and overall survival, were investigated. CD44 and CD24 mRNA expression levels decreased significantly after treatment. However, miR590-3p expression increased after treatment. Patients with complete pathologic responses had upregulated CD24 and downregulated miR590-3p and miR399-3p levels in initial biopsies. Univariate analysis showed that increased expression levels of miR590-3p, miR599, and miR399-3p were significantly associated with shorter disease-free survival. A better understanding of the role of cancer stem cells in cancer can result in more promising results and patient-tailored therapy options. This study highlights the significant value of cancer stem cells and related miRNAs in response to therapy and recurrence.