Objective:

To investigate the development of metaplastic breast cancer in a mouse model and identify potential therapeutic targets.

Approach:

• Mouse Model Creation: Researchers activated the PI3K pathway and deleted the tumor-suppressor gene p53 in Krt15-positive mouse mammary cells using a genetic model (Krt15-CrePR1).
• Tumor Development Observation: Mice developed breast tumors resembling metaplastic breast cancer, with tumors forming only when both copies of p53 were lost.
• Human Case Review: Reviewed 73 cases of metaplastic breast cancer to identify mutations in PIK3CA and TP53.
• Cell Line Creation: Created cell lines from mouse tumors to study marker expression and treatment responses.

Key Findings:

• Tumors included squamous cell carcinoma, carcinosarcoma, sarcoma, and carcinoma.
• Distinct keratin staining patterns were observed in tumors.
• Mutations in PIK3CA and TP53 often co-occurred in human cases, especially in squamous metaplasia.
• Mouse tumor cell lines maintained original tumor characteristics and marker expression.
• Pik3ca-mutant cell lines showed sensitivity to alpelisib, a PI3K inhibitor.

Interpretation:

Limitations:

• Study conducted in a mouse model may not fully replicate human disease.
• Limited effect of androgen receptor blocker enzalutamide suggests complexity in treatment responses.

Conclusion:

Sources:

• The Journal of Pathology