Oncolytic adenoviruses kill breast cancer initiating CD44+CD24-/low cells

Area of Science:

• Oncology
• Virology
• Stem Cell Biology

Background:

• Cancer stem cells (CSCs) drive tumor initiation and relapse in breast cancer.
• CSCs are often resistant to conventional therapies.
• The CD44(+)CD24(-/low) population is implicated as breast CSCs.

Purpose of the Study:

• To evaluate the efficacy of oncolytic adenoviruses against breast CSCs.
• To determine if oncolytic adenoviruses can prevent tumor formation and treat established tumors derived from CSCs.

Main Methods:

• Isolation of CD44(+)CD24(-/low) cells from patient pleural effusions.
• Confirmation of stem cell-like properties (Oct4, Sox2 expression, Hoechst exclusion).
• Treatment of CSCs and orthotopic mouse models with oncolytic adenoviruses (Ad5/3-Delta24, Ad5.pk7-Delta24).

Main Results:

• Isolated CD44(+)CD24(-/low) cells exhibited CSC characteristics.
• Oncolytic adenoviruses effectively killed CD44(+)CD24(-/low) cells, including Hoechst excluding subpopulations.
• Virus infection prevented tumor formation in mice and treated advanced orthotopic tumors.

Conclusions:

• Oncolytic adenoviruses Ad5/3-Delta24 and Ad5.pk7-Delta24 demonstrate potent anti-tumor activity against breast CSCs.
• These viruses are effective against both CSCs and differentiated breast cancer cells.
• Oncolytic adenoviruses represent a promising therapeutic strategy for breast cancer treatment, potentially overcoming CSC-mediated resistance.