Rapamycin Targets Cancer Stem Cells to Decrease Cisplatin Resistance in a Head and Neck Cancer Mouse Xenograft Model

Area of Science:

• Oncology
• Cancer Biology
• Pharmacology

Background:

• Cisplatin is a standard chemotherapy for head and neck squamous cell carcinoma (HNSCC), but resistance limits its effectiveness.
• Cancer stem cells (CSCs) drive cisplatin resistance in HNSCC.
• The mechanistic target of rapamycin (mTOR) pathway is implicated in CSC maintenance and proliferation in HNSCC.

Purpose of the Study:

• To investigate the therapeutic potential of combining rapamycin, an mTOR inhibitor, with cisplatin in HNSCC.
• To evaluate the impact of this combination therapy on CSC populations and tumorigenicity.

Main Methods:

• Assessed CSC gene expression in HNSCC cell lines.
• Evaluated combination therapy efficacy using cell viability assays and a mouse xenograft model.
• Analyzed xenograft tissues for stem cell markers (CD133, ALDH1A1), proliferation (Ki-67), and pathway inhibition (pS6).

Main Results:

• Low-dose cisplatin alone increased CD133+ cells and did not reduce tumor mass in xenografts.
• The combination of cisplatin and rapamycin significantly inhibited tumor growth.
• Combination therapy minimized toxicity and reduced the CD133+ CSC population.

Conclusions:

• Rapamycin enhances cisplatin's efficacy by targeting CD133+ CSCs, reducing chemoresistance.
• This combination therapy offers a promising strategy to overcome CSC-mediated resistance in HNSCC.
• The study supports combining mTOR inhibitors with platinum-based drugs for HNSCC treatment.