Protocatechualdehyde Induced Breast Cancer Stem Cell Death via the Akt/Sox2 Signaling Pathway

Area of Science:

• Oncology
• Pharmacology
• Biochemistry

Background:

• Triple-negative breast cancer (TNBC) presents a significant clinical challenge due to its heterogeneity, lack of targeted therapies, and the prominent role of breast cancer stem cells (BCSCs) in recurrence and treatment resistance.
• Existing treatments for breast cancer, including hormonal and targeted therapies, are often insufficient, leading to persistent early and late relapses, highlighting the need for novel therapeutic strategies.
• Breast cancer stem cells (BCSCs) are crucial drivers of tumor initiation, metastasis, and therapy resistance, making them a critical target for effective breast cancer treatment.

Purpose of the Study:

• To investigate the anti-cancer effects of protocatechualdehyde (PCA), a bioactive compound from *Artemisia princeps*, specifically on breast cancer stem cells (BCSCs).
• To elucidate the molecular mechanisms underlying PCA's action on BCSCs, focusing on key signaling pathways and stem cell markers.
• To evaluate the therapeutic potential of PCA in a preclinical mouse model of breast cancer.

Main Methods:

• Assessed the impact of PCA on breast cancer cell proliferation and mammosphere formation in vitro.
• Quantified changes in the proportion of BCSCs, identified by CD44+/CD24- and aldehyde dehydrogenase 1A (ALDH1A) expression, following PCA treatment.
• Measured the protein levels of Akt, phosphorylated Akt (pAkt), and Sox2 in breast CSCs treated with PCA.
• Evaluated the in vivo efficacy of PCA by measuring tumor volume and weight in a 4T1 breast cancer mouse model.

Main Results:

• PCA demonstrated dose-dependent inhibition of breast cancer cell growth and mammosphere formation.
• PCA treatment significantly reduced the CD44+/CD24- and ALDH1A-expressing populations, indicative of decreased BCSC fraction.
• PCA downregulated the protein levels of Akt, pAkt, and Sox2 in breast CSCs.
• In vivo studies showed that PCA administration reduced tumor volume and weight in mice bearing 4T1 tumors.

Conclusions:

• Protocatechualdehyde exhibits significant anti-tumor activity against breast cancer, particularly by targeting breast cancer stem cells.
• The anti-cancer effects of PCA are mediated through the downregulation of the Akt/pAkt and Sox2 signaling pathways.
• PCA represents a promising natural compound for the development of novel therapeutic strategies for breast cancer, especially for overcoming recurrence and resistance associated with BCSCs.