GSE176580
Preclinical model of anti-PDL1 Immune-checkpoint blockade (ICB) resistance in breast cancer associated to low antigen presentation machinery (APM)
Immune-checkpoint blockade (ICB) immunotherapy has emerged as one of the most effective therapies in oncology by unleashing anti-tumor response. However, despite the improvement in the clinical outcome of TNBC patients, most patients do not respond yet. Thus, to understand the underlying mechanisms of ICB resistance is necessary. With this purpose, we generated a preclinical immunocompetent syngeneic model of anti-PD-L1 ICB resistance. Mouse breast cancer 4TO7 cells were orthotopically implanted by MFP and at 0.5 x 0.5 cm tumor size mice were treated with anti-PD-L1 (10mg/Kg every 3 days). Though tumors initially responded, they eventually developed resistance to anti-PD-L1 treatment. Immunotherapy resistant tumor (IRT) cells and control tumor cells were isolated and validated again for anti-PDL1 resistance in vivo. RNA from isolated resistant tumor cells was obtained using Qiagen RNA extraction kit. Samples were analyzed by bioanalyzer. Poly-A sequencing was selected for library preparation, and samples were sequenced using Illumina Hi-Seq 2500 platform with 1x50 bp settings in the Centre of Genomic Regulation (CRG). Quality raw data was performed with FastQC software. Raw reads were then aligned with the STAR mapper to the Mus musculus genome and raw counts of reads per gene was additionally obtained with STAR. Differentially expression was assessed using DESeq2 version 1.30.1 package from R/Bioconductor. Among all the results, we have seen that those IRT cells have a downregulation of the antigen presentation machinery (APM) and an enrichment of stemness signatures. Overall, the results support the notion that ICB resistance emerge from low APM activity cell populations with associated stem cell-like phenotype. Overall design: Transcriptomic profile of 2 individual biological replicates of cells from ICB resistant to anti-PD-L1 tumors vs control tumors