J Cancer 2019; 10(20):4932-4938. doi:10.7150/jca.32806 This issue

Research Paper

STING signaling is a potential immunotherapeutic target in colorectal cancer

Hong Jae Chon1,2,5*, Hyojoong Kim1,2*, Jung Hyun Noh1,5*, Hannah Yang1,2, Won Suk Lee1,2, So Jung Kong1,2, Seung Jun Lee1,2, Yu Seong Lee1,2, Woo Ram Kim3, Joo Hang Kim1, Gwangil Kim4,5✉, Chan Kim1,2,5✉

1. Medical Oncology, CHA Bundang Medical Center, Seongnam, Korea
2. Laboratory of Translational Immuno-Oncology, Seongnam, Korea
3. Department of Surgery, CHA Bundang Medical Center, Seongnam, Korea
4. Department of Pathology, CHA Bundang Medical Center, Seongnam, Korea
5. CHA Medical School, CHA University, Seongnam, Korea
* These authors equally contributed this work.

This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/). See http://ivyspring.com/terms for full terms and conditions.
Chon HJ, Kim H, Noh JH, Yang H, Lee WS, Kong SJ, Lee SJ, Lee YS, Kim WR, Kim JH, Kim G, Kim C. STING signaling is a potential immunotherapeutic target in colorectal cancer. J Cancer 2019; 10(20):4932-4938. doi:10.7150/jca.32806. Available from https://www.jcancer.org/v10p4932.htm

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Background: Stimulator of Interferon Genes (STING) is an innate immune sensor for cytosolic DNA. STING signaling activation is indispensable for type I interferon response and the anti-cancer immune response by CD8+ T cells. The aim of this study was to characterize intratumoral STING expression pattern and its clinical implication in colorectal cancer (CRC).

Methods: We analyzed STING and CD8 expression in 225 CRC patients who underwent surgical resection. Clinicopathological variables and survival outcomes were analyzed according to STING expression levels. Mice with syngeneic MC38 tumors were also treated with a STING agonist, and tumor microenvironments were analyzed using immunofluorescent staining and flow cytometry.

Results: Distinct STING expression was observed in the CRC tumor specimens. Patients with higher STING expression had early stage cancer with increased intratumoral CD8+ T cell infiltration and less frequent lymphovascular invasion. Compared to CRC patients with lower STING expression, those with higher STING expression had longer overall and recurrence-free survival. Multivariate Cox regression model also revealed higher STING expression to be an independent prognostic factor for better overall survival. When MC38 colon tumors were treated with intratumoral injection of STING agonist, tumor growth was remarkably suppressed with increased intratumoral CD8+ T cell infiltration. Moreover, T-cell activation markers, ICOS and IFN-γ, were also upregulated in CD8+ T cells, indicating enhanced effector T cell function after STING treatment.

Conclusion: We confirmed the distinct STING expression in CRC and demonstrated its independent prognostic value in survival outcomes. STING could be a potential therapeutic target that enhances anti-cancer immune response in CRC.

Keywords: STING, Colorectal cancer, Prognosis, Immunotherapy, Inflamed tumor