Fig. 1

PD-L1 is functionally increased in drug-resistant A549/CDDP, MCF7/ADR and HepG2/ADR cells. PD-L1 expression in drug-resistant A549/CDDP, MCF7/ADR and HepG2/ADR cells and their parental cancer cells were detected by qRT-PCR (a), western blotting (b) and flow cytometry analysis (c, left). The average mean fluorescence intensity (MFI) of PD-L1 expression in these cells detected by flow cytometry was calculated and compared (c, right). All of the above experiments were performed independently in triplicate (S: drug-sensitive; CDDP: cisplatin-resistant; ADR: doxorubicin-resistant). d CD3⁺ T cells isolated from PBMCs were prelabeled with CFSE and cocultured with drug-resistant cancer cells or their parental cells with or without anti-PD-L1 antibodies (αPD-L1). After stimulation with anti-CD3/CD28 antibodies for 72 h, cell proliferation was measured using flow cytometry. ^*P ≤ 0.05, ^**P ≤ 0.01, ^***P ≤ 0.001