Hsp70 modulates immune response in pancreatic cancer through dendritic cells

Heat shock protein 70 (Hsp70), a protein chaperone, is known to promote cell survival and tumor progression. However, its role in the tumor microenvironment (TME) is largely unknown. We specifically evaluated Hsp70 in the TME by implanting tumors in wild-type (WT) controls or Hsp70^-/- animals, thus creating a TME with or without Hsp70. Loss of Hsp70 led to significantly smaller tumors; there were no differences in stromal markers, but interestingly, depletion of CD8 + T-cells abrogated this tumor suppressive effect, indicating that loss of Hsp70 in the TME affects tumor growth through the immune cells. Compared to WT, adoptive transfer of Hsp70^-/- splenocytes exhibited greater antitumor activity in immunodeficient NSG and Rag 1^-/- mice. Hsp70^-/- dendritic cells showed increased expression of MHCII and TNF-α both in vitro and in vivo. These results suggest that the absence of Hsp70 in the TME inhibits tumors through increased dendritic cell activation. Hsp70 inhibition in DCs may emerge as a novel therapeutic strategy against pancreatic cancer.

Gut Microbiota Promotes Tumor Growth in Mice by Modulating Immune Response

We studied the effects of gut microbiome depletion by oral antibiotics on tumor growth in subcutaneous and liver metastases models of pancreatic cancer, colon cancer, and melanoma. Gut microbiome depletion significantly reduced tumor burden in all the models tested. However, depletion of gut microbiome did not reduce tumor growth in Rag1-knockout mice, which lack mature T and B cells. Flow cytometry analyses demonstrated that gut microbiome depletion led to significant increase in interferon gamma-producing T cells with corresponding decrease in interleukin 17A and interleukin 10-producing T cells. Our results suggest that gut microbiome modulation could emerge as a novel immunotherapeutic strategy.

Abstract 5127: Eradication of the gut microbiota reduces cancer burden in multiple models by modulating the immune system

Introduction: Bacteria residing in the human body outnumber ‘human' cells and most of these bacteria exist in the gut. This gut microbiome forms a unique and dynamic metagenome which changes with nutrition and even disease state. A growing body of evidence has implicated the role of the gut microbiome in modulating our immune system. We aimed to investigate this association in murine models of cancer. Methods: C57BL/6 mice were either orally given saline or a gut sterilizing cocktail of poorly absorbable broad-spectrum antibiotics. These mice were used to model multiple cancers, viz. subcutaneous injection of melanoma cells derived from Tyr::CreER; Braf V600E/+;Ptenlox5/lox5 mice, subcutaneous injection of pancreatic cancer cells derived from KPC (Kras LSL.G12D/+; p53 R172H/+ ;Pdx::Cre) mice, intrasplenic injection of KPC pancreatic cancer cells and intrasplenic injection of B16-F10 melanoma cells. The tumors were immunophenotyped through flow cytometry and immunostained for multiple antigens. Mice plasma was used for chemokine analysis. To confirm the role of immunity, subcutaneous experiments were repeated in mice carrying a Rag1tm1Mom mutation (RAG1 knockout), thereby having an immature adaptive immune system. Results: Gut microbiome depletion reduced tumor burden across all four subcutaneous and hepatic metastases models. This effect disappeared when experiments were repeated in immunosuppressed RAG1 knockout mice. Antibiotic-treated tumors had increased TNF-secreting macrophages and NKT cells as well a higher number of iNOS staining cells in the microenvironment. Plasma from antibiotic-treated tumor-bearing mice had decreased levels of CXCL12, a chemokine known to cause tumor immunosuppression. Conclusion: Eradication of the gut microbiota decreases tumor burden by activating the anti-cancer immune system

Citation Format: Vrishketan Sethi, Saba Kurtom, Mohd Tarique, Bhuwan Giri, Bharti Garg, Shweta Lavania, Anthony Ferrantella, Zoe Malchiodi, Leonor Hellmund, Harrys Charles Jacob, Rajinder Dawra, Sulagna Banerjee, Sabita Roy, Sundaram Ramakrishnan, Ashok Saluja, Vikas Dudeja. Eradication of the gut microbiota reduces cancer burden in multiple models by modulating the immune system [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5127.

A conserved Toll-like receptor-to-NF-κB signaling pathway in the endangered coral Orbicella faveolata

Herein, we characterize the Toll-like receptor (TLR)-to-NF-κB innate immune pathway of Orbicella faveolata (Of), which is an ecologically important, disease-susceptible, reef-building coral. As compared to human TLRs, the intracellular TIR domain of Of-TLR is most similar to TLR4, and it can interact in vitro with the human TLR4 adapter MYD88. Treatment of O. faveolata tissue with lipopolysaccharide, a ligand for mammalian TLR4, resulted in gene expression changes consistent with NF-κB pathway mobilization. Biochemical and cell-based assays revealed that Of-NF-κB resembles the mammalian non-canonical NF-κB protein p100 in that C-terminal truncation results in translocation of Of-NF-κB to the nucleus and increases its DNA-binding and transcriptional activation activities. Moreover, human IκB kinase (IKK) and Of-IKK can both phosphorylate conserved residues in Of-NF-κB in vitro and induce C-terminal processing of Of-NF-κB in vivo. These results are the first characterization of TLR-to-NF-κB signaling proteins in an endangered coral, and suggest that these corals have conserved innate immune pathways.