阻斷細胞自噬通量增強膀胱癌表現細胞程式死亡-配體1進而降低抗癌免疫反應

蔡德甫¹、張安辰²、仇光宇¹、陳宏恩¹、何肇晏¹、張朋暉¹、黃一勝^1,3,4

¹新光醫院 泌尿科，²轉譯醫學中心；³台北醫學大學 醫學院；⁴輔仁大學 醫學院

Blockade of the Autophagic Flux Suppresses Antitumor Immunity via Programmed Death Ligand-1 Up-Regulation in Bladder Cancer

Te-Fu Tsai ¹, An-Chen Chang², Kuang-Yu Chou¹, Hung-En Chen¹, Chao-Yen Ho¹, Peng-Hui Chang¹and Thomas I-Sheng Hwang^1,3,4

Department of Urology¹ and Translational Medicine Center², Shin Kong Wu Ho-Su Memorial Hospital; Department of Urology, Taipei Medical University³; Division of Urology, School of Medicine, Fu-Jen Catholic University⁴, Taipei, Taiwan.

Purpose:

A high basal level of autophagic flux in bladder cancer (BC) cells prevents cell death and weakens chemotherapy efficacy. However, how autophagy influences cancer-associated immunosuppression in BC remains undetermined. In this study, we aim to investigate the interplay between autophagic flux and PD-L1 in BC and whether pharmacological modulation of autophagy influences the immunotherapeutic efficacy of PD-L1 blockade in BC. 

Materials and Methods:

The immortalized uroepithelial cells (SV-HUC-1) and human BC cells (5637 and T24) were obtained from the Bioresource Collection and Research Center (BCRC; Hsinchu, Taiwan). Western blot was used to detect LC3-II and PD-L1 protein expression after autophagy inhibitor (CQ or bafilomycin A1) treatment for 24 h. The qPCR assay was performed to measure PD-L1 mRNA level. The membrane-bound PD-L1 (mPD-L1) expression was detected by Flow cytometry. Calcein AM (1 μM), a cell-permeant dye, was used to analyze natural killer (NK) cell-mediated cytotoxicity of BC cells.

Results:

In this study, we observed a negative correlation between the autophagy-related markers LC3-II and PD-L1 in BC cells. The autophagy inhibitors chloroquine (CQ) and bafilomycin A1 (Baf-A1) increased programmed death ligand-1 (PD-L1) expression in BC cells through the ERK–JNK–c-Jun signal-transduction pathway. Moreover, the treatment of BC cells with CQ and Baf-A1 inhibited hsa-microRNA-34a (miR-34a) expression and miR-34a overexpression in BC cells and prevented the autophagy blockade–induced enhancement of PD-L1 expression; an inverse correlation between miR-34a and PD-L1 expression was observed during treatment with autophagy inhibitors. Furthermore, miR-34a overexpression induced the cytotoxic activity of natural killer cells against BC cells. Our results provide evidence that autophagy blockade and its regulatory pathway affect cancer-associated immunosuppression through PD-L1 elevation.

Conclusions: 

Taken together, the coadministration of autophagy inhibitors and a PD-L1 immune checkpoint blockade provides a potential therapeutic approach for treating BC.