Microenvironment and Immunology NF-kB Hyperactivation in Tumor Tissues Allows Tumor- Selective Reprogramming of the ChemokineMicroenvironment to Enhance the Recruitment of Cytolytic T Effector Cells

Tumor infiltration with effector CD8þ T cells (Teff) predicts longer recurrence-free survival in many types of human cancer, illustrating the broad significance of Teff for effective immunosurveillance. Colorectal tumors with reduced accumulation of Teff express low levels of Teff-attracting chemokines such as CXCL10/IP10 and CCL5/RANTES. In this study, we investigated the feasibility of enhancing tumor production of Teff-attracting chemokines as a cancer therapeutic strategy using a tissue explant culture system to analyze chemokine induction in intact tumor tissues. In different tumor explants, we observed highly heterogeneous responses to IFNa or poly-I:C (a TLR3 ligand) when they were applied individually. In contrast, a combination of IFNa and poly-I:C uniformly enhanced the production of CXCL10 and CCL5 in all tumor lesions. Moreover, these effects could be optimized by the further addition of COX inhibitors. Applying this triple combination also uniformly suppressed the production of CCL22/MDC, a chemokine associated with infiltration of T regulatory cells (Treg). The Teff-enhancing effects of this treatment occurred selectively in tumor tissues, as compared with tissues derived from tumor margins. These effects relied on the increased propensity of tumor-associated cells (mostly fibroblasts and infiltrating inflammatory cells) to hyperactivate NF-kB and produce Teff -attracting chemokines in response to treatment, resulting in an enhanced ability of the treated tumors to attract Teff cells and reduced ability to attract Treg cells. Together, our findings suggest the feasibility of exploiting NF-kB hyperactivation in the tumor microenvironment to selectively enhance Teff entry into colon tumors. Cancer Res; 72(15); 3735–43. 2012 AACR. Introduction The ability of CD8þ T cells to infiltrate cancer lesions is essential for antitumor immunity, as evidenced by studies highlighting the prognostic value of effector T (Teff) cells in multiple cancer types, including colorectal cancer (CRC; refs. 1–4). In contrast, tumor infiltration with regulatory T cells (Treg) predicts poor outcomes (5–8). Chemokines and their respective receptors are critical for T-cell migration and homing (9–14). High levels of CCL5/RANTES (CCR5 ligand) and CXCL9/MIG and CXCL10/IP10 (ligands for CXCR3) in tumor tissues are associated with enhanced infiltration of CD8þ T cells in CRC (15), melanoma, and gastric cancer (16, 17). In contrast to the benefits of intratumoral expression of CCL5 and CXCL9-11 (18), high levels of CCL22/MDC, the CCR4 ligand preferentially attracting Treg cells, can be associated with reduced survival, as shown in patients with ovarian cancer (19). Several studies have indicated the propensity of colorectal tumors to overexpress COX2 and its product prostaglandin E2 (PGE2; refs. 20, 21), the factor shown to promote the induction of CCL22 in dendritic cell (DC) cultures (22). Prompted by these reports, and by our observations of the reciprocal impact of IFNa versus PGE2 on the production of Teffand Treg -attracting chemokines in isolated DCs (22), we tested the feasibility of using these factors to manipulate tumor microenvironment to enhance the production of Teff-attracting chemokines in intact human tumor tissues. We used an ex vivo tumor/tissue explant culture system previously applied to study migration of DCs (23), to avoid spontaneous activation of the chemokine-producing cells in the process of tumor dissociation. Guided by reports showing common hyperactivation of NF-kB in cancer tissues (24–27), and the requirement for this factor in the induction of both Tregand Teff-attracting classes of chemokines (28–30), we tested whether the selected PGE2and IFNa-targeting strategies can be used to selectively Authors' Affiliations: Departments of Surgery, Infectious Diseases and Microbiology, Immunology, and Biostatistics, and University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, Pennsylvania Note: Supplementary data for this article are available at Cancer Research Online (http://cancerres.aacrjournals.org/). Corresponding Author:Pawel Kalinski, Department of Surgery, University of Pittsburgh, Hillman Cancer Center, UPCI Research Pavilion, Room 1.46b, 5117 Center Avenue, Pittsburgh, PA 15213. Phone: 412-6237712; Fax: 412-623-7709; E-mail: [email protected] doi: 10.1158/0008-5472.CAN-11-4136 2012 American Association for Cancer Research. Cancer Research www.aacrjournals.org 3735 on May 4, 2017. © 2012 American Association for Cancer Research. cancerres.aacrjournals.org Downloaded from Published OnlineFirst May 16, 2012; DOI: 10.1158/0008-5472.CAN-11-4136