Tumor-Intrinsic PD-L1 Signals Regulate Cell Growth, Pathogenesis, and Autophagy in Ovarian Cancer and Melanoma.
PD-L1 antibodies produce efficacious clinical responses in diverse human cancers, but the basis for their effects remains unclear, leaving a gap in the understanding of how to rationally leverage therapeutic activity. PD-L1 is widely expressed in tumor cells, but its contributions to tumor pathogenicity are incompletely understood. In this study, we evaluated the hypothesis that PD-L1 exerts tumor cell-intrinsic signals that are critical for pathogenesis. Using RNAi methodology, we attenuated PD-L1 in the murine ovarian cell line ID8agg and the melanoma cell line B16 (termed PD-L1locells), which express basal PD-L1. We observed that PD-L1locells proliferated more weakly than control cells in vitro As expected, PD-L1locells formed tumors in immunocompetent mice relatively more slowly, but unexpectedly, they also formed tumors more slowly in immunodeficient NSG mice. RNA sequencing analysis identified a number of genes involved in autophagy and mTOR signaling that were affected by PD-L1 expression. In support of a functional role, PD-L1 attenuation augmented autophagy and blunted the ability of autophagy inhibitors to limit proliferation in vitro and in vivo in NSG mice. PD-L1 attenuation also reduced mTORC1 activity and augmented the antiproliferative effects of the mTORC1 inhibitor rapamycin. PD-L1locells were also relatively deficient in metastasis to the lung, and we found that anti-PD-L1 administration could block tumor cell growth and metastasis in NSG mice. This therapeutic effect was observed with B16 cells but not ID8agg cells, illustrating tumor- or compartmental-specific effects in the therapeutic setting. Overall, our findings extend understanding of PD-L1 functions, illustrate nonimmune effects of anti-PD-L1 immunotherapy, and suggest broader uses for PD-L1 as a biomarker for assessing cancer therapeutic responses. Cancer Res; 76(23); 6964-74. ©2016 AACR.
The Graduate School of Biomedical Sciences, University of Texas Health Science Center, San Antonio, Texas.|Department of Medicine, University of Texas Health Science Center, San Antonio, Texas.
Curtis A
CA
Clark
Department of Medicine, University of Texas Health Science Center, San Antonio, Texas.
Harshita B
HB
Gupta
Cancer Therapy & Research Center, University of Texas Health Science Center, San Antonio, Texas.|Department of Obstetrics and Gynecology, University of Texas Health Science Center, San Antonio, Texas.
Gangadhara
G
Sareddy
Department of Medicine, University of Texas Health Science Center, San Antonio, Texas.
Srilakshmi
S
Pandeswara
Department of Medicine, University of Texas Health Science Center, San Antonio, Texas.
Shunhua
S
Lao
Department of Medicine, University of Texas Health Science Center, San Antonio, Texas.|Department of Molecular Medicine, University of Texas Health Science Center, San Antonio, Texas.
Bin
B
Yuan
The Graduate School of Biomedical Sciences, University of Texas Health Science Center, San Antonio, Texas.|Department of Medicine, University of Texas Health Science Center, San Antonio, Texas.
Justin M
JM
Drerup
Department of Medicine, University of Texas Health Science Center, San Antonio, Texas.
Alvaro
A
Padron
Tumor Microenvironment and Metastasis Program, The Wistar Institute, Philadelphia, Pennsylvania.
José
J
Conejo-Garcia
The Graduate School of Biomedical Sciences, University of Texas Health Science Center, San Antonio, Texas.|Department of Medicine, University of Texas Health Science Center, San Antonio, Texas.
Kruthi
K
Murthy
Department of Medicine, University of Texas Health Science Center, San Antonio, Texas.|Xiangya School of Medicine, Central South University, Changsha, Hunan, PR China.
Yang
Y
Liu
Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire.
Mary Jo
MJ
Turk
Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands and Department for Neuroscience, School of Medicine and Health Sciences, University Oldenburg, Oldenburg, Germany.
Kathrin
K
Thedieck
Department of Medicine, University of Texas Health Science Center, San Antonio, Texas.
Vincent
V
Hurez
The Graduate School of Biomedical Sciences, University of Texas Health Science Center, San Antonio, Texas.|Cancer Therapy & Research Center, University of Texas Health Science Center, San Antonio, Texas.|Department of Molecular Medicine, University of Texas Health Science Center, San Antonio, Texas.
Rong
R
Li
The Graduate School of Biomedical Sciences, University of Texas Health Science Center, San Antonio, Texas.|Cancer Therapy & Research Center, University of Texas Health Science Center, San Antonio, Texas.|Department of Obstetrics and Gynecology, University of Texas Health Science Center, San Antonio, Texas.
Ratna
R
Vadlamudi
The Graduate School of Biomedical Sciences, University of Texas Health Science Center, San Antonio, Texas. curielt@uthscsa.edu.|Department of Medicine, University of Texas Health Science Center, San Antonio, Texas.|Cancer Therapy & Research Center, University of Texas Health Science Center, San Antonio, Texas.
Tyler J
TJ
Curiel
D000818:Animals; D001343:Autophagy; D060890:B7-H1 Antigen / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005260:Female; D006801:Humans; D008545:Melanoma / Q000235:genetics*; D051379:Mice; D018345:Mice, Knockout; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000473:pathology; D015398:Signal Transduction; D014162:Transfection
D060890:B7-H1 Antigen; C423236:CD274 protein, human
Nat Rev Mol Cell Biol. 2015 Aug;16(8):461-72
26177004
Nature. 2015 Jan 22;517(7535):489-92
25363767
Nature. 2015 Jul 9;523(7559):231-5
25970248
Science. 2011 Jun 10;332(6035):1322-6
21659605
EMBO J. 2012 Mar 7;31(5):1095-108
22343943
Curr Opin Immunol. 2012 Apr;24(2):207-12
22236695
J Immunol. 2013 Oct 1;191(7):3955-67
24018273
N Engl J Med. 2012 Jun 28;366(26):2443-54
22658127
Mol Cell. 2006 Apr 21;22(2):159-68
16603397
J Exp Med. 2003 May 5;197(9):1083-91
12719480
Science. 2005 Feb 18;307(5712):1098-101
15718470
Tumour Biol. 2016 Jul;37(7):9465-72
26787540
Nat Rev Immunol. 2008 Jun;8(6):467-77
18500231
Autophagy. 2014 Aug;10(8):1403-14
24991835
Nat Methods. 2012 Jul;9(7):671-5
22930834
J Immunol. 2010 Sep 1;185(5):2747-53
20686128
Oncotarget. 2016 Feb 9;7(6):6891-901
26771843
J Exp Clin Cancer Res. 2015 Sep 11;34:97
26361755
Nat Rev Cancer. 2012 Mar 22;12(4):252-64
22437870
Nat Med. 2003 May;9(5):562-7
12704383
Nat Rev Mol Cell Biol. 2011 Jan;12(1):21-35
21157483
Nat Immunol. 2001 Mar;2(3):269-74
11224528
Cell. 2006 Oct 6;127(1):125-37
16962653
J Biol Chem. 2005 Dec 9;280(49):40406-16
16221682
Cell. 2015 Sep 10;162(6):1229-41
26321679
Blood. 2008 Apr 1;111(7):3635-43
18223165
Cancer Cell. 2007 Jul;12(1):9-22
17613433
Cancer Cell. 2014 Aug 11;26(2):190-206
25117709
Cell. 2012 Apr 13;149(2):274-93
22500797
PLoS One. 2013;8(1):e55096
23383069
Infect Agent Cancer. 2012 Jan 03;7(1):1
22214493
Carcinogenesis. 2000 Apr;21(4):585-91
10753190
Cell. 2015 Sep 10;162(6):1242-56
26359984
Science. 2011 Jun 10;332(6035):1317-22
21659604
Proc Natl Acad Sci U S A. 2013 Oct 22;110(43):17450-5
24101526
Science. 2011 Nov 4;334(6056):678-83
22053050
Science. 2012 Mar 30;335(6076):1638-43
22461615
Cancer Prev Res (Phila). 2015 May;8(5):400-9
25736275
Sci Transl Med. 2012 Mar 28;4(127):127ra37
22461641
Nature. 2011 Jul 13;475(7355):226-30
21753853
Nat Med. 2002 Aug;8(8):793-800
12091876
Nature. 2013 Oct 10;502(7470):194-200
24089209
N Engl J Med. 2012 Jun 28;366(26):2455-65
22658128
J Immunol. 2011 Aug 1;187(3):1097-105
21697456