ATR suppresses the pro-tumorigenic functions of breast stromal fibroblasts

Area of Science:

• Cell Biology
• Oncology
• Molecular Biology

Background:

• The ATR protein kinase regulates cellular responses to DNA damage and replication stress.
• The role of ATR in human carcinogenesis is not fully understood.
• ATR levels are often reduced in cancer-associated fibroblasts (CAFs).

Purpose of the Study:

• To investigate the role of ATR in breast carcinogenesis.
• To determine the impact of ATR levels on fibroblast function and tumor progression.
• To explore the potential of ATR as a diagnostic/prognostic marker.

Main Methods:

• Investigated ATR levels in CAFs versus normal fibroblasts.
• Utilized ATR knockdown and ectopic expression in breast fibroblasts.
• Assessed paracrine effects on breast cancer cells and tumor growth in xenografts.
• Examined the role of p53 in ATR-deficient cell-mediated cancer promotion.

Main Results:

• Reduced ATR levels in CAFs correlated with increased pro-carcinogenic factors (SDF-1, IL-6).
• ATR-deficient fibroblasts enhanced tumor growth, aggressiveness, and cancer cell migration/invasion.
• Ectopic ATR expression suppressed cancer-promoting proteins and inhibited fibroblast pro-carcinogenic activities.
• p53 expression counteracted the cancer-promoting effects of ATR-deficient cells.

Conclusions:

• ATR acts as a tumor suppressor in breast fibroblasts by inhibiting both autocrine and paracrine pro-carcinogenic effects.
• ATR deficiency in fibroblasts contributes to breast cancer progression.
• ATR status in breast fibroblasts holds significant prognostic and diagnostic potential for breast cancer.