Background and purpose: Programmed death ligand-1 (PD-L1) plays an important role in sheltering tumor cell from surveillance of immune system. While the potential modulation is regarded as being performed at MAPK

PI3K-AKT and STAT3 pathway in most cases

the key control point has never been explicitly reported. This study aimed to probe on this mechanism of lung carcinoma via PI3K/AKT pathway based on the A549 and H460 cell lines. Methods: By using shRNA technology

we created several selectively ‘silent’ mutations of A 549 and H460 cell lines

involving A549

HEB-

A549

HTF4-

A549

Nrf2-

A549

FOXO3a-

H460

HEB-

H460

HTF4-

H460

Nrf2-

and H460

FOXO3a-

. 3’UTR region of PD-L1 was constructed into pGL3-basic vector in order to create a dual luciferase reporter gene system which was able to be used for monitoring the transcriptional activation of PD-L1. Real-time fluorescence quantitative polymerase chain reaction (RTFQ-PCR) was used to detect the transcriptional level of PD-L1

and the Western blot assay was used for monitoring the total expression of PD-L1; peripheral blood mononuclear cells (PBMCs) co-culturing with A549 and H460 cell lines were utilized to check the function of Nrf2 in tumor immune resistance. Results: Phosphorylation level of AKT and expression level of PD-L1 in A549 and H460 cell lines were simultaneously enhanced after treatment with 10 μg/mL insulin (P0.001)

and the same phenomenon was observed in their mutations with defect in HEB

HTF4 and FOXO3a respectively

however

the plot reversal occurred in A549

Nrf2-

and H460

Nrf2-

cell lines (P0.001). Isoproterenol could boost both transcriptional activation and expression level in A549 and H460 cell lines

and this auto-acti

on was able to be relieved by NAC. Results above further certified the transcriptional regulation of Nrf2 on PD-L1 gene. Wortmannin could change over the function of insulin to raise the expression of PD-L1

by prohibiting the increasing AKT phosphorylation level. Furthermore

the relationship between the phosphorylation level of Nrf2 and AKT was also analyzed by using Wortmannin and insulin

and the results confirmed that the two parties correlated to each other positively

for the correlation coefficient r was 0.86 and 0.93 in A549 and H460 cell lines respectively. At last

A549

Nrf2-

and h460

Nrf2-

cell lines became more sensitive to the attack of PBMCs than that of their wild type owing to Nrf2-deficiency

for increased apoptosis was observed in co-culture experiment. Conclusion: PI3K/AKT pathway plays a vital role in regulating PD-L1 expression in A549 and H460 cell lines

and this action is potentially realized via phosphorylating Nrf2.