Correlation Between PIK3R1 Expression and Cell Growth in Human Breast Cancer Cell Line BT-474 and Clinical Outcomes

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• PIK3CA mutations are key in breast cancer development.
• PIK3R1 gene alterations represent actionable targets for cancer therapy.
• Understanding PIK3R1's role in breast carcinoma is crucial for treatment strategies.

Purpose of the Study:

• To investigate the role of PIK3R1 in breast carcinoma cell proliferation.
• To correlate PIK3R1 expression levels with patient outcomes in breast cancer.
• To analyze the impact of PIK3R1 on overall survival (OS) and disease-free survival (DFS).

Main Methods:

• Utilized the BT-474 (ER+/HER2-high) breast cancer cell line for in vitro studies.
• Performed PIK3R1 gene knockdown (ΔPIK3R1) to assess effects on cell proliferation.
• Retrospectively reviewed data from 440 breast cancer patients (2000-2015).
• Employed human breast cancer tissue arrays for immunostaining and correlation analysis.

Main Results:

• PIK3R1 knockdown in BT-474 cells led to increased cell proliferation and altered cell cycle distribution (increased S and G2M fractions).
• Reduced PIK3R1 protein levels correlated with increased p-AKT and p-mTOR signaling.
• High PIK3R1 expression in early-stage (I/II) breast cancer patients was associated with improved DFS and OS.

Conclusions:

• Downregulation of PIK3R1 promotes cell growth and activates AKT-mTOR signaling in breast cancer cells.
• Elevated PIK3R1 protein expression is a positive prognostic marker for early-stage breast cancer patients.
• PIK3R1 status may inform treatment decisions and predict outcomes in specific breast cancer stages.