Tumor Cell-derived HMGB1-initiated Activation of Treg Abstract High-mobility group box 1 (HMGB1) in tumor cells and the tumor microenvironment (TME) is tied to the hallmarks of tumor development and progression, but its role in tumor-induced immune suppression is unclear. We found that stable silencing of HMGB1 in tumor cells or specific inhibiting of extracellular HMGB1 in the TME reduced tumor-induced activation of regulatory T cells (Treg) and uncovered spontaneous CD8 T cell-dependent antitumor immunity in multiple murine tumor models, suggesting that tumor cell-derived HMGB1 may trigger Treg activation. Also, we found that tumor cell-derived HMGB1 promoted the production of thymic stromal lymphopoietin (TSLP) by tumor cells. Further, we found that tumor cell-derived HMGB1 and TSLP acted together to modulate dendritic cells (DC) to activate Treg. We hypothesize that growing tumor cell-derived HMGB1 acts as an extracellular signal on tumor cells to heighten TSLP, which in turn `partners' with HMGB1, to modulate DC to activate Treg. We will test this central hypothesis with 2 specific aims: 1) Define how HMGB1 heightens TSLP in tumor cells 2) Dissect how HMGB1 modulates DC to activate Treg This study will have led to a novel concept that HMGB1 is immune suppressive during tumor progression. Novel findings -- that uncover a previously unknown function of HMGB1 as an extracellular signal elevating TSLP in tumor cells and reveal an innovative mechanistic connection between HMGB1 and TSLP in Treg activation via DC -- will advance our understanding of how tumors induce Treg activation.

Public Health Relevance

This study identifies a novel tumor-derived factor for mediating tumor immune suppression and provides new insights into understanding the tumor-induced suppression of antitumor activity. Understanding molecular and cellular mechanisms of tumor-derived factors in mediating tumor immune suppression might raise the hope to circumvent the negative regulator, thus opening the door to novel approaches to cancer treatment and prevention.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21CA191522-02
Application #
9066604
Study Section
Special Emphasis Panel (ZCA1)
Program Officer
Mccarthy, Susan A
Project Start
2015-07-01
Project End
2017-06-30
Budget Start
2016-07-01
Budget End
2017-06-30
Support Year
2
Fiscal Year
2016
Total Cost
Indirect Cost
Name
University of Pittsburgh
Department
Dermatology
Type
Schools of Medicine
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213