Abstract | BACKGROUND: METHODS: We analyzed publicly available mRNA and protein expression data from the cancer genome/ proteome atlas and performed immunohistochemistry on tumors with known TP53 status. Constitutive and IFN-ɣ-induced PD-L1 expression upon p53 knockdown in wildtype, TP53-mutated or JAK2-overexpressing melanoma cells or in cells, in which p53 was rendered transcriptionally inactive by CRISPR/Cas9, was determined by immunoblot or flow cytometry. Similarly, PD-L1 expression was investigated after overexpression of a transcriptionally-impaired p53 (L22Q, W23S) in TP53-wt or a TP53-knockout melanoma cell line. Immunoblot was applied to analyze the IFN-ɣ signaling pathway. RESULTS: For TP53-mutated tumors, an increased CD274 mRNA expression and a higher frequency of PD-L1 positivity was observed. Interestingly, positive correlations of IFNG mRNA and PD-L1 protein in both TP53-wt and -mutated samples and of p53 and PD-L1 protein suggest a non-transcriptional mode of action of p53. Indeed, cell line experiments revealed a diminished IFN-ɣ-induced PD-L1 expression upon p53 knockdown in both wildtype and TP53-mutated melanoma cells, which was not the case when p53 wildtype protein was rendered transcriptionally inactive or by ectopic expression of p53L22Q,W23S, a transcriptionally-impaired variant, in TP53-wt cells. Accordingly, expression of p53L22Q,W23S in a TP53-knockout melanoma cell line boosted IFN-ɣ-induced PD-L1 expression. The impaired PD-L1-inducibility after p53 knockdown was associated with a reduced JAK2 expression in the cells and was almost abrogated by JAK2 overexpression. CONCLUSIONS: While having only a small impact on basal PD-L1 expression, both wildtype and mutated p53 play an important positive role for IFN-ɣ-induced PD-L1 expression in melanoma cells by supporting JAK2 expression. Future studies should address, whether p53 expression levels might influence response to anti-PD-1 immunotherapy.
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Authors | Alexander Thiem, Sonja Hesbacher, Hermann Kneitz, Teresa di Primio, Markus V Heppt, Heike M Hermanns, Matthias Goebeler, Svenja Meierjohann, Roland Houben, David Schrama |
Journal | Journal of experimental & clinical cancer research : CR
(J Exp Clin Cancer Res)
Vol. 38
Issue 1
Pg. 397
(Sep 11 2019)
ISSN: 1756-9966 [Electronic] England |
PMID | 31506076
(Publication Type: Journal Article)
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Chemical References |
- B7-H1 Antigen
- Biomarkers, Tumor
- CD274 protein, human
- RNA, Small Interfering
- TP53 protein, human
- Tumor Suppressor Protein p53
- Interferon-gamma
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Topics |
- B7-H1 Antigen
(genetics)
- Biomarkers, Tumor
- Cell Line, Tumor
- Gene Editing
- Gene Expression Regulation, Neoplastic
(drug effects)
- Gene Targeting
- Humans
- Interferon-gamma
(metabolism, pharmacology)
- Melanoma
(genetics, immunology, metabolism)
- RNA, Small Interfering
(genetics)
- Signal Transduction
- Tumor Suppressor Protein p53
(genetics)
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