Mammary-specific expression of Trim24 establishes a mouse model of human metaplastic breast cancer.

Shah, Vrutant V; Duncan, Aundrietta D; Jiang, Shiming; Stratton, Sabrina A; Allton, Kendra L; Yam, Clinton; Jain, Abhinav; Krause, Patrick M et al. · Nat Commun · 2021

basic_science · Level V

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Abstract

Conditional overexpression of histone reader Tripartite motif containing protein 24 (TRIM24) in mouse mammary epithelia (Trim24<sup>COE</sup>) drives spontaneous development of mammary carcinosarcoma tumors, lacking ER, PR and HER2. Human carcinosarcomas or metaplastic breast cancers (MpBC) are a rare, chemorefractory subclass of triple-negative breast cancers (TNBC). Comparison of Trim24<sup>COE</sup> metaplastic carcinosarcoma morphology, TRIM24 protein levels and a derived Trim24<sup>COE</sup> gene signature reveals strong correlation with human MpBC tumors and MpBC patient-derived xenograft (PDX) models. Global and single-cell tumor profiling reveal Met as a direct oncogenic target of TRIM24, leading to aberrant PI3K/mTOR activation. Here, we find that pharmacological inhibition of these pathways in primary Trim24<sup>COE</sup> tumor cells and TRIM24-PROTAC treatment of MpBC TNBC PDX tumorspheres decreased cellular viability, suggesting potential in therapeutically targeting TRIM24 and its regulated pathways in TRIM24-expressing TNBC.

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