PD-L1 Is Upregulated by Simultaneous Amplification of the PD-L1 and JAK2 Genes in Non-Small Cell Lung Cancer


The programmed death ligand 1(PD-L1)/programmed cell death protein 1 (PD-1) pathway is one of the most important checkpoint pathways for mediating tumor-induced immune suppression through T-cell exhaustion. Recently, targeted therapies using monoclonal antibodies against components of this pathway have been shown to reduce tumor burden in patients with non-small cell lung cancer (NSCLC). However, the prognostic significance of PD-L1 expression is controversial and the precise mechanisms of PD-L1 gene activation in lung cancer have yet to be clarified.


We investigated copy number alterations (CNAs) in the PD-L1 gene by real-time PCR in 94 surgically resected lung cancer samples to find possible associations between PD-L1 CNA and lung cancer biology. Janus kinase 2 gene (JAK2) CNA and its influence on the PD-L1/PD-1 pathway were also assessed.


Five samples were shown to have PD-L1 gene amplification, whereas 89 samples did not. The patients with PD-L1 amplification had worse prognoses than did those without PD-L1 amplification. Genetic amplification of the PD-L1 gene was correlated with JAK2 gene amplification. The lung cancer cell line HCC4006 was found to harbor both JAK2 and PD-L1 amplification. Flow cytometry analyses revealed the level of PD-L1 protein expression to be higher in HCC4006 cells than in other NSCLC cell lines. Expression of the PD-L1 protein was significantly reduced by the JAK2 inhibitor TG-101348 and the signal transducer and activator of transcription 3 (STAT-3) inhibitor BP-1-102, but not by the STAT1 inhibitor fludarabine.


Our data suggest that expression of PD-L1 protein is upregulated by the simultaneous amplification of the PD-L1 and JAK2 genes through JAK-STAT signaling in NCSLC.

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S2736 Fedratinib (TG101348) Fedratinib (SAR302503, TG101348) is a selective inhibitor of JAK2 with IC50 of 3 nM in cell-free assays, 35- and 334-fold more selective for JAK2 versus JAK1 and JAK3. Fedratinib also inhibits FMS-like tyrosine kinase 3 (FLT3) and RET (c-RET) with IC50 of 15 nM and 48 nM, respectively. Fedratinib has potential antineoplastic activity. Fedratinib inhibits proliferation and induces apoptosis. Phase 2. (58) (4)

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