Purpose: The plasticity of innate lymphoid cells (ILCs) has been reported in vitro and in the microenvironment of the intestine. However, whether ILC plasticity contributes to regulation of the tumor microenvironment remains unknown. In this study, we explored plasticity of ILCs in human lung cancer.
Experimental design: We analyzed immune subsets and cytokine expression in lung cancers freshly obtained from 80 patients and explored conversion of ILC1 into ILC3 in coculture with lung cancer cells. Prognostic effects of converted ILC3 and related pathway were evaluated by retrospective cohort composed of 875 patients with lung cancer.
Results: Low percentages of ILC1, and high percentages of ILC3 were found in pulmonary squamous cell carcinomas (SqCC) but not adenocarcinomas (ADC). In non-small-cell lung cancers, the percentage of ILC3 was associated with IL23 expression in tumor cells but not immune cells. In cocultures, tumor cells of SqCCs converted ILC1 into ILC3 by producing IL23, thus promoting IL17-mediated tumor cell proliferation. Consistently, among IL17+ immune cells, the percentages of ILCs were higher in SqCCs than ADCs. Furthermore, the numbers of CD3-RORγt+ ILC3, IL17 expression level, and IL23- or IL17RA-expressing tumor cells were associated with short survival of patients with SqCC but not ADC.
Conclusions: Conversion from ILC1 into ILC3 by IL23-producing SqCCs promotes IL17-mediated tumor progression, resulting in a poor prognosis.
©2019 American Association for Cancer Research.