Imbusch, C. | bioRxiv Science

bioRxiv2022

Chronic chromosome instability induced by Plk1 results in immune suppression in breast cancer

Chromosomal instability (CIN), the inability to correctly segregate chromosomes during cell division, is a common characteristic of solid tumors. CIN contributes to tumor evolution by promoting intratumor heterogeneity, thus facilitating resistance to cancer therapies. In vitro studies have demonstrated that cells with complex karyotypes are recognized and eliminated by natural killer (NK) cells. Paradoxically, it has also been observed that human tumors with high levels of CIN have an immunosuppressive phenotype. It remains unclear which CIN-associated molecular features alter immune recognition during tumor evolution. Previous studies with Polo-like kinase 1 (Plk1) overexpression in Her2-positive breast tumors, resulted in increased levels of CIN and delayed tumorigenesis. Using this mouse model, we show that high CIN tumors activate a senescence-associated secretory phenotype (SASP) and become immune evasive by activating RELB signaling and upregulating PD-L1 in a non-cell-autonomous manner. Single-cell RNA sequencing of immune cells from early-stage induced mammary glands revealed that macrophages, NK cells, B cells and regulatory T cells are programmed to a suppressive phenotype during tumor development. In human tumors, we further establish the importance of RELB/p38 signaling in understanding the interplay between CIN and the immune system, highlighting the need for novel adjuvant therapies in the context of chromosomally unstable tumors.

cancer biology↗

bioRxiv2022

High-resolution epigenetic profiling identifies novel regulators of COPD in human lung fibroblasts

Patients with chronic obstructive pulmonary disease (COPD) are still waiting for curative treatments. Considering the environmental cause of COPD (e.g., cigarette smoke) and disease phenotypes, including stem-cell senescence and impaired differentiation, we hypothesized that COPD will be associated with altered epigenetic signaling in lung cells. We generated genome-wide DNA methylation maps at single CpG resolution of primary human lung fibroblasts (HLFs) isolated from distal parenchyma of ex-smoker controls and COPD patients, with both mild and severe disease. The epigenetic landscape is markedly changed in lung fibroblasts across COPD stages, with DNA methylation changes occurring predominantly in regulatory regions, including promoters and enhancers. RNA sequencing of matched fibroblasts demonstrated dysregulation of genes involved in proliferation, DNA repair, and extracellular matrix organization. Notably, we identified epigenetic and transcriptional dysregulation already in mild COPD patients, providing unique insights into early disease. Integration of profiling data identified 110 candidate regulators of disease phenotypes, including epigenetic factors. Using phenotypic screens, we verified the regulator capacity of multiple candidates and linked them to repair processes in the human lung. Our study provides first integrative high-resolution epigenetic and transcriptomic maps of human lung fibroblasts across stages of COPD. We reveal novel transcriptomic and epigenetic signatures associated with COPD onset and progression and identify new candidate regulators involved in the pathogenesis of chronic respiratory diseases. The presence of various epigenetic factors among the candidates demonstrates that epigenetic regulation in COPD is an exciting research field that holds promise for novel therapeutic avenues for patients.

cell biology↗