Dissecting tumor vs. stroma transcriptome in PDAC xenografts: MRP4 as an inductor of stromal activation

ANA SAHORES; SAMANTA N GANCEDO; MAXIMILIANO DE SOUSA SERRO; JUAN F GONZALEZ; NATALIA GOMEZ; MARIA MAY; CARINA SHAYO; CARLOS DAVIO; BETINA GONZALEZ

Congreso; Reunion Anual de Sociedades de Biociencia 2022; 2022

The xenobiotic transporter MRP4/ABCC4 is involved in the regulation of cAMP signaling by extrusion to the extracellular compartment. MRP4 is highly expressed in pancreatic ductal adenocarcinoma (PDAC), and is linked to increased proliferation, a mesenchymal phenotype and poor prognosis. PDACs are characterized by a dense fibrotic (desmoplastic) stroma, mainly composed by cancer activated fibroblasts (CAFs) and extracellular matrix, that determines the interaction between cancer cells and their microenvironment, and also promotes tumor progression and chemoresistance. The aim of our study was to evaluate the effect of tumor MRP4 overexpression on the stromal compartment. We established PDAC xenografts by sc. inoculation of BxPC3 cells in NSG mice, with stable transfection of either ABCC4 (MRP4+) or empty vector (mock). These xenografts consist of human parenchyma and murine stroma, mostly fibroblasts. Tumortranscriptome was evaluated by RNAseq, and the obtained FASTQ files were aligned to human and mouse reference genomes. The obtained BAM files were processed with Xenofilter, an algorithm specifically developed to discriminate human and mouse reads. The mouse count matrix was analyzed with DESeq2, and the differentially expressed genes (DEGs) were evaluated for functional enrichment (gene ontology and pathway analysis). We detected 49 DEGs in murine stromal cells from MRP4+ vs. mock xenografts. Particularly, stromal upregulated genes showed significative enrichment (FDR