Ammerpohl, O. | bioRxiv Science

bioRxiv2026

SERPINB13 is a prognostic biomarker for LUSC associated with an immune-inflamed tumor phenotype and modulated by immune cells

Non-small cell lung cancer (NSCLC) is the most common form of lung cancer accounting for most cancer-related deaths worldwide. Despite substantial recent advances in targeted therapies and immunotherapy, the prognosis for advanced-stage disease remains comparably poor, which is why the identification of novel molecular biomarkers as well as therapeutic targets influencing tumor development, progression, and metastasis remain important. This study focusses on SERPINB13, a serine-protease inhibitor expressed in selected tissues that is dysregulated in several tumor entities. However, its role in NSCLC still remains largely unclear. We analyzed SERPINB13 transcription in a cohort of non-small cell lung cancer (NSCLC) cases including both lung squamous cell carcinoma (LUSC) and lung adenocarcinoma (LUAD) by transcriptome profiling. Epigenetic modifications were assessed via Methylation BeadChips. Additionally, SERPINB13 protein expression was assessed by immunohistochemistry (IHC) in an independent cohort of NSCLC comprising 126 LUSC patients. Correlation analyses were performed to associate SERPINB13 expression with key clinico-pathological parameters, including overall survival and extent of tumor-infiltrating immune cells. To functionally investigate the regulatory influence of peripheral blood mononuclear cells (PBMCs) on SERPINB13 expression in LUSC tumor cells in vitro, we utilized the SERPINB13-expressing LUSC cell line LUDLU-1. Here, gene transcription was analyzed by quantitative real-time PCR (RT-qPCR), confirmed by Western blot on the protein level. Transcriptome analysis revealed a significant upregulation of SERPINB13 in lung squamous cell carcinoma (LUSC) compared to lung adenocarcinoma (LUAD), highlighting a subtype-specific expression pattern. This differential expression was further associated with a distinct epigenetic DNA methylation signature at the SERPINB13 loci in LUSC, suggesting transcriptional regulation via hypomethylation. IHC analysis demonstrated that high SERPINB13 protein expression is significantly associated with prolonged overall survival in LUSC. Notably, SERPINB13 expression was enriched in immune-inflamed ("hot") tumors, characterized by elevated infiltrating lymphocytes and immune activation. Mechanistically, co-culture experiments with PBMCs induced SERPINB13 expression in a LUSC cell line in a dose- and time-dependent manner in the absence of direct cell contact. This suggests that soluble factors secreted by immune cells might play a key role in regulating SERPINB13 expression in the tumor microenvironment. Taken together, SERPINB13 is a novel prognostic indicator in LUSC that is modulated by Immune cells. Further studies are necessary to decipher the crosstalk of Immune cells on the Serpin B13 expressing tumor cells in depth, with regard to a possible interventional strategy. immunomodulatory potential strategies and personalized therapeutic approaches in NSCLC.

pathology↗

bioRxiv2024

SETDB1 activity is globally directed by H3K14 acetylation via its Triple Tudor Domain

SETDB1 is a major H3K9 methyltransferase involved in heterochromatin formation and silencing of repeat elements. It contains a unique Triple Tudor Domain (3TD) which specifically binds the dual modification of H3K14ac in the presence of H3K9me1/2/3. Here, we explored the role of the 3TD H3-tail interaction for the H3K9 methylation activity of SETDB1. We generated a binding reduced 3TD mutant and demonstrate in biochemical methylation assays on peptides and recombinant nucleosomes containing H3K14ac analogs, that H3K14 acetylation is crucial for the 3TD mediated recruitment of SETDB1. We also observe this effect in cells where SETDB1 binding and activity is globally correlated with H3K14ac, and KO of the H3K14 acetyltransferase HBO1 causes a drastic reduction in H3K9me3 levels at SETDB1 dependent sites. Further analyses revealed that 3TD particularly important at specific target regions like L1M repeat elements, where SETDB1 KO cannot be efficiently reconstituted by the 3TD mutant of SETDB1. In summary, our data demonstrate that the H3K9me3 and H3K14ac are not antagonistic marks but rather the presence of H3K14ac is required for SETDB1 recruitment via 3TD binding to H3K9me1/2/3-K14ac and establishment of H3K9me3.

biochemistry↗

bioRxiv2018

Repeat expansion and methylation state analysis with nanopore sequencing

Expansions of short tandem repeats are genetic variants that have been implicated in neuropsychiatric and other disorders but their assessment remains challenging with current molecular methods. Here, we developed a Cas12a-based enrichment strategy for nanopore sequencing that, combined with a new algorithm for raw signal analysis, enables us to efficiently target, sequence and precisely quantify repeat numbers as well as their DNA methylation status. Taking advantage of these single molecule nanopore signals provides therefore unprecedented opportunities to study pathological repeat expansions.

genetics↗