Migrating Type 2 Dendritic Cells Prime Mucosal Th17 Cells Specific to Small Intestinal Commensal Bacteria

Dendritic cells (DCs) are professional APCs equipped with MHC-restricted Ags, costimulations, and cytokines that effectively prime and differentiate naive T cells into distinct functional subsets. The immune signals that DCs carry reflect the route of Ag uptake and the innate stimuli they received. In the mucosal tissues, owing to the great variety of foreign Ags and inflammatory cues, DCs are predominantly activated and migratory. In the small intestine, CD4 Th17 cells are abundant and have been shown to be regulated by DCs and macrophages. Using a mouse commensal bacteria experimental model, we identified that the early priming step of commensal-driven Th17 cells is controlled by bona fide Zbtb46-expressing DCs. CCR7-dependent migration of type 2 DCs (DC2s) from the small intestine to the mesenteric lymph nodes (MLNs) is essential for the activation of naive CD4 T cells. The migratory DC2 population in the MLNs is almost exclusively Esam+ cells. Single-cell RNA sequencing highlighted the abundance of costimulatory markers (CD40 and OX40) and chemokines (Ccl22 and Cxcl16) on MLN migratory DCs. Further resolution of MLN migratory DC2s revealed that the Th17-polarizing cytokine IL-6 colocalizes with DC2s expressing CD40, Ccl17, and Ccl22. Thus, early Th17 cell differentiation is initiated by a small subset of migratory DC2s in the gut-draining lymph nodes.

Molecular chaperone GP96 is a potential target to modulate dendritic cell programming and shape anti-tumor immunity

Dendritic cells (DCs) are professional antigen-presenting cells providing costimulatory signals to adaptive immune cells. Currently, the lack of strategies to improve antigen presentation is a hindrance in tumor immunology. Despite studies focusing on antigen cross-presenting Type-1 DCs (DC1s), a study published by our lab revealed Type-2 DCs (DC2s) with significant survival across multiple human cancers. Our research group has a long-term interest in studying immune chaperone GP96, which is an essential molecular chaperone for TLRs, GARP, and other vital innate receptors. The immune-related client network of GP96 creates opportunities to unmask the roles of multiple receptors on DCs. We have generated DC-specific GP96 deficient mice and reported increased tumor-infiltrating DC2 and delayed tumor development on the spontaneous breast cancer model. However, the mechanism by which GP96 regulates DCs function is under investigation. Using different tumor models, we found that deletion of GP96 on DCs improved immune response and decreased tumor growth. However, macrophage-GP96KO mice showed a loss of benefits observed on DC-GP96KO mice. Also, differential stimulatory/inhibitory molecules on DC1 vs. DC2 were tumor-dependent. To determine the role of DC-intrinsic GP96 in T cell activation, we used in vitro antigen-cross presentation assay. We found that OT-I CD8+ T cell activation was delayed at the initial days of the co-culture with GP96KO DCs but restored in the late phase compared with WT DCs. Collectively, the results show beneficial inflammatory DC2 molecular activation, with DC1 able to cross-present antigens to CD8+ T cells. Our study indicated that targeting GP96 on DCs may contribute to shaping T cell anti-tumor immunity.

Supported by grants from NIH NCI (R01:CA193939) and NIH NIAID (U01:AI125859)

Type-2 dendritic cells mediate control of cytotoxic T cell-resistant tumors

Type 2 DCs (DC2s) comprise the majority of conventional DCs within most tumors; however, little is known about their ability to initiate and sustain antitumor immunity, as most studies have focused on antigen cross-presenting DC1s. Here, we report that DC2 infiltration identified by analysis of multiple human cancer data sets showed a significant correlation with survival across multiple human cancers, with the benefit being seen in tumors resistant to cytotoxic T cell control. Characterization of DC subtype infiltration into an immunotherapy-resistant model of breast cancer revealed that impairment of DC1s through 2 unique models resulted in enhanced DC2 functionality and improved tumor control. BATF3 deficiency depleted intratumoral DC1s, which led to increased DC2 lymph node migration and CD4⁺ T cell activation. Enhancing DC2 stimulatory potential by genetic deletion of Hsp90b1 (encoding molecular chaperon GP96) led to a similar enhancement of T cell immunity and improved survival in a spontaneous breast cancer model. These data highlight the therapeutic and prognostic potential of DC2s within checkpoint blockade–resistant tumors.

Molecular Chaperone GRP94/GP96 in Cancers: Oncogenesis and Therapeutic Target

During tumor development and progression, intrinsic and extrinsic factors trigger endoplasmic reticulum (ER) stress and the unfolded protein response, resulting in the increased expression of molecular chaperones to cope with the stress and maintain tumor cell survival. Heat shock protein (HSP) GRP94, also known as GP96, is an ER paralog of HSP90 and has been shown to promote survival signaling during tumor-induced stress and modulate the immune response through its multiple clients, including TLRs, integrins, LRP6, GARP, IGF, and HER2. Clinically, elevated expression of GRP94 correlates with an aggressive phenotype and poor clinical outcome in a variety of cancers. Thus, GRP94 is a potential molecular marker and therapeutic target in malignancies. In this review, we will undergo deep molecular profiling of GRP94 in tumor development and summarize the individual roles of GRP94 in common cancers, including breast cancer, colon cancer, lung cancer, liver cancer, multiple myeloma, and others. Finally, we will briefly review the therapeutic potential of selectively targeting GRP94 for the treatment of cancers.

Evaluating the efficacy of enzalutamide and the development of resistance in a preclinical mouse model of type-I endometrial carcinoma

Androgen Receptor (AR) signaling is a critical driver of hormone-dependent prostate cancer and has also been proposed to have biological activity in female hormone-dependent cancers, including type I endometrial carcinoma (EMC). In this study, we evaluated the preclinical efficacy of a third-generation AR antagonist, enzalutamide, in a genetic mouse model of EMC, Sprr2f-Cre;Pten^fl/fl. In this model, ablation of Pten in the uterine epithelium leads to localized and distant malignant disease as observed in human EMC. We hypothesized that administering enzalutamide through the diet would temporarily decrease the incidence of invasive and metastatic carcinoma, while prolonged administration would result in development of resistance and loss of efficacy. Short-term treatment with enzalutamide reduced overall tumor burden through increased apoptosis but failed to prevent progression of invasive and metastatic disease. These results suggest that AR signaling may have biphasic, oncogenic and tumor suppressive roles in EMC that are dependent on disease stage. Enzalutamide treatment increased Progesterone Receptor (PR) expression within both stromal and tumor cell compartments. Prolonged administration of enzalutamide decreased apoptosis, increased tumor burden and resulted in the clonal expansion of tumor cells expressing high levels of p53 protein, suggestive of acquired Trp53 mutations. In conclusion, we show that enzalutamide induces apoptosis in EMC but has limited efficacy overall as a single agent. Induction of PR, a negative regulator of endometrial proliferation, suggests that adding progestin therapy to enzalutamide administration may further decrease tumor burden and result in a prolonged response.

Abstract 627: Evaluating the efficacy of enzalutamide and the development of resistance in a preclinical mouse model of type-I endometrial carcinoma

Androgen Receptor (AR) signaling is a critical driver of hormone-dependent prostate cancer and has also been proposed to have biological activity in female hormone-dependent cancers, including type I endometrial carcinoma (EMC). In this study, we evaluated the preclinical efficacy of a third-generation AR antagonist, enzalutamide, in a genetic mouse model of EMC, Sprr2f-Cre;Ptenfl/fl. In this model, ablation of Pten in the uterine epithelium leads to localized and distant malignant disease as observed in human EMC. We hypothesized that administering enzalutamide through the diet would temporarily decrease the incidence of invasive and metastatic carcinoma, while prolonged administration would result in development of resistance. Short-term treatment with enzalutamide reduced overall tumor burden through increased apoptosis but failed to prevent progression of invasive and metastatic disease suggesting that AR signaling may have biphasic, oncogenic and tumor suppressive roles in EMC. Enzalutamide treatment increased Progesterone Receptor (PR) expression within both stromal and tumor cell compartments. Prolonged administration of enzalutamide decreased apoptosis, increased tumor burden and resulted in the clonal expansion of tumor cells expressing high levels of p53 protein, suggestive of acquired Trp53 mutations. In conclusion, we show that enzalutamide induces apoptosis in EMC but has limited efficacy overall as a single agent. Induction of PR, a negative regulator of endometrial proliferation, suggests that adding progestin therapy to enzalutamide administration may further decrease tumor burden and result in a prolonged response.

Citation Format: Christopher Steven Koivisto, Parrish Melodie, Bonala Santosh, Soo Ngoi, Georges J. Nahhas, Bei Liu, Adrian Torres, James Gallagher, Rebekah Snchez-Hodge, Victor Zeinner, David Cohn, Floor Backes, Paul Goodfellow, Helen Chamberlin, Gustavo Leone. Evaluating the efficacy of enzalutamide and the development of resistance in a preclinical mouse model of type-I endometrial carcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 627.

Specific Subset of Dendritic Cells Control the Priming of Mucosal Th17 Cells

Phagocytic mononuclear cells play an essential role in regulating gut immune homeostasis by sensing, internalizing microbial parts, and subsequently driving adaptive response in an antigen- and cytokine-dependent context. In a healthy host, physiological Th17 cells are predominantly generated in the gut, induced by local commensal microbiota. However, the precise subpopulation of antigen-presenting cells responsible for imprinting Th17 program in naïve CD4 T cells have not yet been definitively identified.

Objective

Mapping the functional subset of Th17-inducing dendritic cells (DCs) will uncover new targets for mucosal vaccine design.

Methods & Results

Using transgenic CD4 T cells specifically recognizing a gut-colonizing commensal bacterial antigen, we found that migratory DCs (CD11chiMHCIIhiZbtb46+) in the mesenteric lymph nodes are indispensable for the initial Th17 cell priming. Whereas the absence of CD103+ or CX3CR1+ DCs did not impact Th17 cell differentiation. Single cell RNA sequencing revealed that the migratory DCs are highly heterogeneous and consist of 8 clusters of transcriptionally specialized subsets. Interleukin-6, the Th17-polarizing cytokine, is expressed by a minor population of DCs with a type I interferon signature. Our results indicate that during homeostasis, Th17 cells activation in the mesenteric lymph nodes and later persistence in the small intestine may be controlled and sustained by different groups of antigen-presenting cells. The complexity and heterogeneity of mucosal DCs imply that other effector and regulatory T cell responses may be regulated by different DC subsets at this unique tissue environment.

Expression of nitric oxide synthase, cyclooxygenase, and p53 in different stages of human gastric cancer

The present study evaluated the significance of nitric oxide synthase (NOS), cyclooxygenase (COX) expression and p53 status in 55 patients with gastric adenocarcinoma and relationship of these molecular markers to tumor characteristics and metastatic potential. Immunohistochemical technique was used to identify the cellular location and distribution of the enzymes in the specific cells of gastric tumors. In gastric cancer tissue, the expression of inducible enzymes, iNOS and COX-2, increased significantly with increasing tumor stage (P=0.015, P=0.001, respectively), size (P=0.025, P=0.001, respectively) and the presence of metastases (P=0.002, P=0.015, respectively). The expression of constitutive enzymes, ecNOS and COX-1, followed the opposite pattern. COX-1 was significantly reduced in advanced gastric tumors (P=0.007) and tumors larger than 5 cm (P=0.007). Reduced expression of ecNOS was also observed in advanced gastric tumors; however, this did not reach statistical significance. 53% of gastric tumors showed accumulation of p53. This was significantly higher in advanced tumors (P=0.004), larger than 5 cm (P=0.015) with metastases (P<0.001). Gastric tumors positive for accumulation of p53 had significantly stronger expression of iNOS (P=0.018) and COX-2 (P=0.01) enzymes than tumors negative for this nucleophosphoprotein. We conclude, that tumor-associated nitric oxide production, as well as COX-2 overexpression, may promote gastric cancer progression by providing a selective growth advantage to tumor cells with non-functioning p53.

K-ras mutation in colorectal carcinomas from singapore

54 sporadic colorectal cancers were analyzed for aberrations in the K-ras oncogene. DNA was extracted from frozen tissues obtained from surgical resection and analyzed for mutations in codons 12, 13 and 61 of the K-ras oncogene using single strand conformation polymorphism analysis (SSCP) and direct sequencing. Point mutations in the K-ras oncogene were found in 26/54 (48%) cases, all of which resulted in amino acid substitutions. No other types of mutations (e.g. insertions or deletions) were found. 4 of the mutations were at codon 12, 22 in codon 13 and only 1 was a codon 61 mutant. G-->A transitions were found to be predominant. A remarkable finding was the high preponderance of (13)Gly-(13)Ser mutations (54%). No correlation was observed between K-ras mutations and tumor location, Dukes' stage, differentiation levels, age or sex of the patient.