PDL1 Regulation by p53 via miR-34

Abstract

Background:Although clinical studies have shown promise for targeting PD1/PDL1 signaling in non–small cell lung cancer (NSCLC), the regulation of PDL1 expression is poorly understood. Here, we show that PDL1 is regulated by p53 via miR-34.Methods:p53 wild-type and p53-deficient cell lines (p53–/– and p53+/+ HCT116, p53-inducible H1299, and p53-knockdown H460) were used to determine if p53 regulates PDL1 via miR-34. PDL1 and miR-34a expression were analyzed in samples from patients with NSCLC and mutated p53 vs wild-type p53 tumors from The Cancer Genome Atlas for Lung Adenocarcinoma (TCGA LUAD). We confirmed that PDL1 is a direct target of miR-34 with western blotting and luciferase assays and used a p53R172HΔg/+K-rasLA1/+ syngeneic mouse model (n = 12) to deliver miR-34a–loaded liposomes (MRX34) plus radiotherapy (XRT) and assessed PDL1 expression and tumor-infiltrating lymphocytes (TILs). A two-sided t test was applied to compare the mean between different treatments.Results:We found that p53 regulates PDL1 via miR-34, which directly binds to the PDL1 3’ untranslated region in models of NSCLC (fold-change luciferase activity to control group, mean for miR-34a = 0.50, SD = 0.2, P < .001; mean for miR-34b = 0.52, SD = 0.2, P = .006; and mean for miR-34c = 0.59, SD = 0.14, and P = .006). Therapeutic delivery of MRX34, currently the subject of a phase I clinical trial, promoted TILs (mean of CD8 expression percentage of control group = 22.5%, SD = 1.9%; mean of CD8 expression percentage of MRX34 = 30.1%, SD = 3.7%, P = .016, n = 4) and reduced CD8+PD1+ cells in vivo (mean of CD8/PD1 expression percentage of control group = 40.2%, SD = 6.2%; mean of CD8/PD1 expression percentage of MRX34 = 20.3%, SD = 5.1%, P = .001, n = 4). Further, MRX34 plus XRT increased CD8+ cell numbers more than either therapy alone (mean of CD8 expression percentage of MRX34 plus XRT to control group = 44.2%, SD = 8.7%, P = .004, n = 4). Finally, miR-34a delivery reduced the numbers of radiation-induced macrophages (mean of F4-80 expression percentage of control group = 52.4%, SD = 1.7%; mean of F4-80 expression percentage of MRX34 = 40.1%, SD = 3.5%, P = .008, n = 4) and T-regulatory cells.Conclusions:We identified a novel mechanism by which tumor immune evasion is regulated by p53/miR-34/PDL1 axis. Our results suggest that delivery of miRNAs with standard therapies, such as XRT, may represent a novel therapeutic approach for lung cancer.

Correlation and prognostic significance of PD-L1 and P53 expression in resected primary pulmonary lymphoepithelioma-like carcinoma

“…In a recent report on the mechanism, Cortez MA and his colleagues elucidated that P53 can regulate PD-L1 expression via microRNA34. There was also a concerning correlation between PD-L1 expression and P53 mutation status (8). We also found that the P53 (+) population had a higher incidence of patients with PD-L1 (+) in TCs (85.3% vs. 45.5%, P=0.001), but found no positive correlation between expression levels of P53 and PD-L1 in TCs.…”

“…In addition, recent reports found that mutated P53 can modulate PD-L1 expression via microRNA34 and that nuclear P53 and membranous PD-L1 expression levels were correlated in non-small cell lung cancer (NSCLC) (8,9). It is well-known that P53 mutations, which are strongly linked with mutation burdens of lung cancer and poor survival, have been detected in greater than half of patients with NSCLC (10).…”

miRNAs as Biomarkers and Therapeutic Targets in Non-Small Cell Lung Cancer: Current Perspectives

“…PD-L1 can also be regulated by p53 via the miR-34 family, which directly binds to the 3′UTR of the PD-L1 transcript [134]. NSCLC patients with high miR-34a/p53 and low PD-L1 levels are characterized by higher survival rates than those with low miR-34a/p53 and high PD-L1 levels.…”

“…The therapeutic approach presented in another preclinical work on miR-34 showed that this miRNA directly represses the checkpoint molecule PD-L1 (programmed death ligand 1) in a mouse model of non-squamous lung cancer [134]. Therapeutic delivery of MRX34 (miR-34 mimic) promoted the TILs (tumour-infiltrating lymphocytes, CD8+) and reduced CD8 + PD1+ immune cells.…”

Non-coding RNAs: the cancer genome dark matter that matters!

“…The plethora of reports argue that microRNAs are master regulator of cancer biology, and deregulated expression of microRNAs affects all hallmarks of cancer [32] (Figure 2): (1) sustaining proliferative signaling (miR-21, let-7) [33,34]; (2) evading growth suppressors (miR-221 and miR-222) [35]; (3) resisting cell death (miR-34a, miR15a/16-1) [36,37]; (4) enabling replicative immortality (miR-29, miR-19b) [38,39]; (5) inducing angiogenesis (miR-210, miR-17-92 cluster) [40,41]; (6) activating invasion and metastasis (miR-10b, miR-224) [25,42]; (7) reprogramming energy metabolism (miR-23, miR-103) [43,44]; (8) evading immune destruction (miR-34a, miR-124a) [45,46].…”