FACT-seq: profiling histone modifications in formalin-fixed paraffin-embedded samples with low cell numbers.

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Zhao L, Xing P, Polavarapu VK, Zhao M, Valero-Martínez B, Dang Y, Maturi N, Mathot L, Neves I, Yildirim I, Swartling FJ, Sjöblom T, Uhrbom L, Chen X

Nucleic Acids Res. 49 (21) e125 [2021-12-02; online 2021-09-18]

The majority of biopsies in both basic research and translational cancer studies are preserved in the format of archived formalin-fixed paraffin-embedded (FFPE) samples. Profiling histone modifications in archived FFPE tissues is critically important to understand gene regulation in human disease. The required input for current genome-wide histone modification profiling studies from FFPE samples is either 10-20 tissue sections or whole tissue blocks, which prevents better resolved analyses. But it is desirable to consume a minimal amount of FFPE tissue sections in the analysis as clinical tissues of interest are limited. Here, we present FFPE tissue with antibody-guided chromatin tagmentation with sequencing (FACT-seq), the first highly sensitive method to efficiently profile histone modifications in FFPE tissues by combining a novel fusion protein of hyperactive Tn5 transposase and protein A (T7-pA-Tn5) transposition and T7 in vitro transcription. FACT-seq generates high-quality chromatin profiles from different histone modifications with low number of FFPE nuclei. We proved a very small piece of FFPE tissue section containing ∼4000 nuclei is sufficient to decode H3K27ac modifications with FACT-seq. H3K27ac FACT-seq revealed disease-specific super enhancers in the archived FFPE human colorectal and human glioblastoma cancer tissue. In summary, FACT-seq allows decoding the histone modifications in archival FFPE tissues with high sensitivity and help researchers to better understand epigenetic regulation in cancer and human disease.

PubMed 34534335

DOI 10.1093/nar/gkab813

Crossref 10.1093/nar/gkab813

pmc: PMC8643707
pii: 6371973