TY - JOUR
T1 - JAK2 and PD-L1 Amplification Enhance the Dynamic Expression of PD-L1 in Triple-negative Breast Cancer
AU - Chen, Meixuan
AU - Pockaj, Barbara
AU - Andreozzi, Mariacarla
AU - Barrett, Michael T.
AU - Krishna, Sri
AU - Eaton, Seron
AU - Niu, Ruifang
AU - Anderson, Karen
N1 - Publisher Copyright:
© 2018 The Authors
PY - 2018/10
Y1 - 2018/10
N2 - Background: Activation of the JAK/STAT pathway is common in triple-negative breast cancer (TNBC) and affects the expression of genes controlling immune signaling. A subset of TNBC cases will have somatic amplification of chromosome 9p24.1, encoding PD-L1, PD-L2, and JAK2, which has been associated with decreased survival. Materials and Methods: Eleven TNBC cell lines were evaluated using array comparative genomic hybridization. A copy number gain was defined as an array comparative genomic hybridization log2 ratio of = 1. Cell surface expression of programmed cell death ligand 1 (PD-L1) was detected using flow cytometry and compared with the median fluorescence intensity of isotype control immunoglobulin. To selectively inhibit JAK2, lentiviral vectors encoding 2 different short hairpin RNA (shRNA) were generated. JAK2, STAT1, STAT3, phosphorylated (p) STAT1, and pSTAT3 expression were measured by immunoblot. Statistical significance was defined as P < .05. Results: The cell line HCC70 had 9p24.1 copy number amplification that was associated with both increased JAK2 and pSTAT3; however, knockdown of JAK2 inhibited cell growth independently of 9p24.1 copy number status. In TNBC cell lines with 9p24.1 gain or amplification, PD-L1 expression rapidly and strikingly increased 5- to 38-fold with interferon-γ (P < .05), and inducible PD-L1 expression was completely blocked by JAK2 knockdown and the JAK1/2 inhibitor ruxolitinib. In tumor tissue, expression of interferon-γ-related genes correlated with 9p24.1 copy number status. Conclusion: These data suggest that the JAK2/STAT1 pathway in TNBC might regulate the dynamic expression of PD-L1 that is induced in the setting of an inflammatory response. Inhibition of JAK2 might provide a synergistic therapy when combined with other immunotherapies in the subset of TNBC with 9p24.1 amplification.
AB - Background: Activation of the JAK/STAT pathway is common in triple-negative breast cancer (TNBC) and affects the expression of genes controlling immune signaling. A subset of TNBC cases will have somatic amplification of chromosome 9p24.1, encoding PD-L1, PD-L2, and JAK2, which has been associated with decreased survival. Materials and Methods: Eleven TNBC cell lines were evaluated using array comparative genomic hybridization. A copy number gain was defined as an array comparative genomic hybridization log2 ratio of = 1. Cell surface expression of programmed cell death ligand 1 (PD-L1) was detected using flow cytometry and compared with the median fluorescence intensity of isotype control immunoglobulin. To selectively inhibit JAK2, lentiviral vectors encoding 2 different short hairpin RNA (shRNA) were generated. JAK2, STAT1, STAT3, phosphorylated (p) STAT1, and pSTAT3 expression were measured by immunoblot. Statistical significance was defined as P < .05. Results: The cell line HCC70 had 9p24.1 copy number amplification that was associated with both increased JAK2 and pSTAT3; however, knockdown of JAK2 inhibited cell growth independently of 9p24.1 copy number status. In TNBC cell lines with 9p24.1 gain or amplification, PD-L1 expression rapidly and strikingly increased 5- to 38-fold with interferon-γ (P < .05), and inducible PD-L1 expression was completely blocked by JAK2 knockdown and the JAK1/2 inhibitor ruxolitinib. In tumor tissue, expression of interferon-γ-related genes correlated with 9p24.1 copy number status. Conclusion: These data suggest that the JAK2/STAT1 pathway in TNBC might regulate the dynamic expression of PD-L1 that is induced in the setting of an inflammatory response. Inhibition of JAK2 might provide a synergistic therapy when combined with other immunotherapies in the subset of TNBC with 9p24.1 amplification.
KW - Biomarker
KW - Checkpoint blockade
KW - Immunotherapy
KW - Programmed cell death ligand 1
KW - TNBC
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U2 - 10.1016/j.clbc.2018.05.006
DO - 10.1016/j.clbc.2018.05.006
M3 - Article
C2 - 29933930
AN - SCOPUS:85048775557
SN - 1526-8209
VL - 18
SP - e1205-e1215
JO - Clinical Breast Cancer
JF - Clinical Breast Cancer
IS - 5
ER -