Dataset Information

Melanoma dedifferentiation induced by interferon-gamma epigenetic remodeling in response to anti-PD-1 therapy

ABSTRACT: Melanoma dedifferentiation has been reported as a state of cellular resistance to targeted therapies and immunotherapies as cancer cells revert to a more primitive cellular phenotype. Here we show that, counterintuitively, the biopsies of patient tumors that respond to anti-programmed cell death receptor 1 (PD-1) therapy decreased expression of melanocytic markers and increased neural crest markers, suggesting treatment-induced dedifferentiation. When modeling the effects in vitro, we documented that melanoma cell lines that were originally melanocytic differentiated underwent a process of neural crest dedifferentiation when continuously exposed to interferon gamma (IFNγ), through a global chromatin landscape changes leading to enrichment in specific hyperaccessible chromatin regions. The IFNγ-induced dedifferentiation signature corresponded with improved outcomes in patients with melanoma, challenging the notion that neural crest dedifferentiation is entirely an adverse phenotype.

ORGANISM(S): Homo sapiens

PROVIDER: GSE152755 | GEO | 2021/05/10

REPOSITORIES: GEO

ACCESS DATA

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

Project description:Background Melanoma cells frequently dedifferentiate in response to inflammation which can increase responses to certain cytokines. Interferon-γ (IFNγ) is an integral part of the anti-tumour immune response and can directly induce both differentiational changes and expression of immunosuppressive proteins in melanoma cells. How the differentiation status of melanoma cells affects IFNγ responses remains unclear. Methods Dedifferentiation of melanoma cells was induced via either siRNA or shRNA mediated MITF knockdown and the cells were subsequently treated with IFNγ. Effects of MITF knockdown and IFNγ treatment on gene expression were evaluated via qPCR and RNA sequencing. A Luminex assay was used to analyse the effects of dedifferentiation and IFNγ treatment on cytokine secretion. Effects on PD-L1 protein expression were analysed via flow cytometry and western blotting. Inhibition of the JAK kinases, NF-κB and STAT3 with small molecule inhibitors, and siRNA mediated knockdown of STAT1 and IRF1 was applied to investigate the molecular mechanism behind IFNγ induced PD-L1 expression in dedifferentiated melanoma cells. The effects of inhibitor treatments and siRNA mediated knockdowns were evaluated via qPCR and western blotting. Bioinformatic analyses of publicly available RNA sequencing data, consisting of 45 patient derived melanoma cell lines, with or without IFNγ treatment, was conducted to assess the generalisability of the in vitro results. Results Dedifferentiation renders 624Mel melanoma cells hypersensitive to IFNγ stimulation in a context-dependent manner, resulting in non-additive upregulation of IFNγ-induced genes, increased PD-L1 protein expression and amplified secretion of CCL2, CXCL10 and IL-10. Furthermore, the intensified PD-L1 protein expression occurs through the JAK-STAT1-IRF1 axis. Lastly, dedifferentiated patient derived melanoma cell lines showed enhanced inflammatory signalling in response to IFNγ compared to differentiated cells, and tended to have higher PD-L1 expression, associated with increased IRF1 expression and activity. Conclusions Together, these findings indicate the existence of a molecular context linking dedifferentiation and IFNγ signalling in melanoma which may lead to immune evasion. Furthermore, these results imply that modulating melanoma differentiation may help shape IFNγ responsiveness.

Project description:Despite advances in therapeutics, the progression of melanoma to metastasis still confers a poor outcome to patients. Nevertheless, there is a lack of biological models to understand cellular and molecular changes taking place along disease progression. Here, we analyzed the transcriptome of a multi-stage murine model of melanoma progression comprising a non-tumorigenic melanocyte lineage (melan-a), pre-malignant melanocytes (4C), non-metastatic (4C11-) and metastasis-prone (4C11+) melanoma cells. Clustering analyses have grouped the four cell lines according to their differentiated (melan-a and 4C11+) or undifferentiated/“mesenchymal-like” (4C and 4C11-) morphologies, suggesting dynamic gene expression patterns associated with the transition between these phenotypes. The cell plasticity observed in the murine melanoma progression is corroborated by molecular markers described for cell subtypes during human melanoma differentiation, as the differentiated cell lines in our model exhibit upregulation of transitory and melanocytic markers, whereas mesenchymal-like cells show increased expression of markers from undifferentiated and neural crest-like states. Sets of differentially expressed genes (DEGs) were detected at each transition step of tumor progression, and transcriptional signatures related to malignancy, metastasis and epithelial-to-mesenchymal transition were identified. Finally, DEGs were mapped to their human orthologs and subsequently evaluated in uni- and multivariate survival analysis using gene expression and clinical data of 703 drug-naïve primary melanoma patients, revealing several independent candidate prognostic markers. Altogether, these results provide novel insights into the molecular mechanisms underlying the phenotypic switch taking place during melanoma progression, reveal potential drug targets and prognostic biomarkers, and corroborate the translational relevance of this unique sequential model of melanoma progression.

Dataset Information

Melanoma dedifferentiation induced by interferon-gamma epigenetic remodeling in response to anti-PD-1 therapy

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets