Rictor promotes tumor progression of rapamycin-insensitive triple-negative breast cancer cells

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Triple-negative breast cancer (TNBC) has a poor prognosis and limited therapeutic options.
• The PI3K/AKT/mTOR pathway is frequently activated in TNBC, making mTOR inhibitors like rapamycin potential treatments.
• However, some TNBCs exhibit intrinsic resistance or develop acquired resistance to these inhibitors.

Purpose of the Study:

• To investigate the role of rapamycin-insensitive companion of mTOR (Rictor) in TNBC sensitivity to rapamycin.
• To determine if Rictor expression can serve as a predictive marker for rapamycin analog therapy in TNBC.
• To explore Rictor as a therapeutic target for overcoming resistance to mTOR inhibitors in TNBC.

Main Methods:

• Assessed the correlation between Rictor expression levels and TNBC cell sensitivity to rapamycin.
• Utilized genetic manipulation (repression of Rictor expression) to evaluate its impact on tumor cell growth.
• Investigated the efficacy of Rictor suppression in TNBC cells resistant to mTOR kinase inhibitors.

Main Results:

• TNBC cell sensitivity to rapamycin was found to be highly dependent on Rictor expression levels.
• Repressing Rictor expression significantly inhibited the growth of rapamycin-insensitive TNBC cells.
• Suppression of Rictor was also effective in TNBC cells that had acquired resistance to mTOR kinase inhibitors.

Conclusions:

• Rictor expression levels can serve as a predictive biomarker for the efficacy of rapamycin analogs in TNBC.
• Targeting Rictor presents a promising therapeutic strategy to overcome rapamycin resistance in TNBC.
• Further development of Rictor-targeting therapeutics is warranted for TNBC treatment.