CONICET | Buscador de Institutos y Recursos Humanos

The multidrug resistance-associated protein 4 MRP4/ABCC4 is a xenobiotic transporter highly expressed in pancreatic ductal adenocarcinoma (PDAC), thas was found linked to increased proliferation and poor prognosis. We queried ChIP-seq and RNA-seq data from PDAC cell lines available at public repositories including the Gene Expression Omnibus (GEO) and the Encyclopedia of DNA Elements (ENCODE), analyzing Abcc4 mRNA levels and the associated epigenetic landscape of histone marks with clear functions in gene expression: H3K27ac/H3K4me for cis-regulatory elements indicative of active clusters of transcription factors (TFs), H3K4me3 for active promoters, H3K9me3 for silenced heterochromatin, and the TFs reported bound at those genomic locations. All cell lines presented H3K4me3 enrichment at the Abcc4 promoter and were depleted of H3K9me3. The high Abcc4-expressing cell lines, such as PANC1, consistently showed H3K27ac/H3K4me enrichment at specific locations of intron1, which were not detected in low Abcc4-expressing cell lines, such as HPAF2. We overlapped these regions with the TFs peaks reported in high Abcc4-expressing CFPAC1 cell line and defined three TFs clusters for further analysis. We generated HPAF2, BxPC3 and PANC1 xenografted tumors in NGS mice and evaluated Abcc4 mRNA expression (RT-PCR) and chromatin enrichment (ChIP-PCR) of H3K27ac, FoxA1 and GATA2 at the intron1 clusters. We found Abcc4 mRNA levels as expected: low in HPAF2 and increased in BxPC3 and PANC1. H3K27ac showed enrichment at the three clusters in all tumors, indicative of active/poised state, but only high Abcc4-expressing BxPC3 and PANC1 showed enrichment of FoxA1/GATA2 at these genomic locations. FoxA1 was found enriched at all clusters only in BxPC3. GATA2 showed enrichment at clusters 2 and 3 in BxPC3 and PANC1, and at cluster 1 only in PANC1. These findings suggest that FoxA1 and GATA2 may contribute to aberrant Abcc4 expression, PDAC aggressiveness and progression.