A Syngeneic ErbB2 Mammary Cancer Model for Preclinical Immunotherapy Trials [microarray]

A cell line was derived from a mammary carcinoma in the transgenic FVB/N-Tg(MMTV-ErbB2)NDL2-5Mul mouse. The line, referred to as “NDL(UCD)” is adapted to standard cell culture and can be transplanted into syngeneic FVB/N mouse. The line maintains stable phenotype over multiple in vitro passages and rounds of in vivo transplantation. The cell line exhibits high expression of ErbB2 and ErbB3 and signaling molecules downstream ErbB2. The line was previously shown to be reactive to anti-immune checkpoint therapy with responses conducive to immunotherapy studies. Here, using both histology/immunophenotyping and gene expression/microarray analysis, we show that the syngeneic transplant tumors elicit an immune reaction in the adjacent stroma, with additional tumor infiltrating lymphocytes. We also show that this immune activating effect is greater in the syngeneic transplants than in the tumors arising in the transgenic mouse. We further analyzed the PD-1 and PD-L-1 expression in the model and found strong PD-L1 expression in the tumors and in vitro. Three distinct transplantable syngenic mouse models of mammary carcinoma were compared to identify differentially expressed genes. For evaluating differential gene expression of the tumors arose from the NDL(UCD), Met1(UCD) and SSM2(UCD) cell lines grown in the FVB mouse we collected snap-frozen tumor samples, and three samples per model were processed in Mouse Gene 1.0 ST Array.