Early stability and late random tumor progression of a HER2-positive primary breast cancer patient-derived xenograft

• Published in: Scientific reports Vol. 11; no. 1; pp. 1563 - 14
• Main Authors: Landuzzi, Lorena, Palladini, Arianna, Ceccarelli, Claudio, Asioli, Sofia, Nicoletti, Giordano, Giusti, Veronica, Ruzzi, Francesca, Ianzano, Marianna L., Scalambra, Laura, Laranga, Roberta, Balboni, Tania, Arigoni, Maddalena, Olivero, Martina, Calogero, Raffaele A., De Giovanni, Carla, Dall’Ora, Massimiliano, Di Oto, Enrico, Santini, Donatella, Foschini, Maria Pia, Cucchi, Maria Cristina, Zanotti, Simone, Taffurelli, Mario, Nanni, Patrizia, Lollini, Pier-Luigi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 15.01.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 631/67/1059; 631/67/1347; 631/67/2329; 631/67/70; 631/67/71; Breast cancer; Enzyme inhibitors; ErbB-2 protein; Gene expression; Growth rate; Humanities and Social Sciences; Immunodeficiency; Kinases; Mesenchyme; Metastases; Monoclonal antibodies; multidisciplinary; Phenotypes; Protein-tyrosine kinase; Science; Science (multidisciplinary); Senescence; Stem cells; Targeted cancer therapy; Trastuzumab; Xenografts
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-81085-y

We established patient-derived xenografts (PDX) from human primary breast cancers and studied whether stability or progressive events occurred during long-term in vivo passages (up to 4 years) in severely immunodeficient mice. While most PDX showed stable biomarker expression and growth phenotype, a HER2-positive PDX (PDX-BRB4) originated a subline (out of 6 studied in parallel) that progressively acquired a significantly increased tumor growth rate, resistance to cell senescence of in vitro cultures, increased stem cell marker expression and high lung metastatic ability, along with a strong decrease of BCL2 expression. RNAseq analysis of the progressed subline showed that BCL2 was connected to three main hub genes also down-regulated (CDKN2A, STAT5A and WT1). Gene expression of progressed subline suggested a partial epithelial-to-mesenchymal transition. PDX-BRB4 with its progressed subline is a preclinical model mirroring the clinical paradox of high level-BCL2 as a good prognostic factor in breast cancer. Sequential in vivo passages of PDX-BRB4 chronically treated with trastuzumab developed progressive loss of sensitivity to trastuzumab while HER2 expression and sensitivity to the pan-HER tyrosine kinase inhibitor neratinib were maintained. Long-term PDX studies, even though demanding, can originate new preclinical models, suitable to investigate the mechanisms of breast cancer progression and new therapeutic approaches.