Pro- and anti-tumorigenic capacity of immunoproteasomes in shaping the tumor microenvironment
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ABSTRACT:
PROVIDER: PRJNA634311 | ENA |
REPOSITORIES: ENA
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Project description:Apart from the constitutive proteasome, the immunoproteasome that comprises the three proteolytic subunits LMP2, MECL-1 and LMP7 is expressed in most immune cells. In this study we describe two opposing roles for immunoproteasomes in regulating the tumor microenvironment. During chronic inflammation, immunoproteasomes modulated the expression of pro-tumorigenic cytokines and chemokines and enhanced infiltration of innate immune cells that led to the onset of colitis-associated carcinogenesies (CAC). In ulcerative colitis (UC) patients with high risk for CAC, immunoproteasome-induced pro-tumorigenic mediators were highly upregulated. Interestingly, the role for the same enzymatic complex in melanoma tumors is relatively unknown. We found that the high expression of immunoproteasomes in human melanoma was associated with better prognosis. Our data revealed that the immunoproteasome has a strong anti-tumorigenic function in cancer types with non-inflammatory microenvironment such as melanoma. CD8+ cytotoxic T lymphocytes (CTLs) from immunoproteasome-deficient mice were reduced during T cell homeostasis and were not able to combat melanoma efficiently. Our results indicate that the immunoproteasome exhibits either pro- or anti-tumoral properties in a context-dependent manner.
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Project description:Apart from the constitutive proteasome, the immunoproteasome that comprises the three proteolytic subunits LMP2, MECL-1, and LMP7 is expressed in most immune cells. In this study, we describe opposing roles for immunoproteasomes in regulating the tumor microenvironment (TME). During chronic inflammation, immunoproteasomes modulated the expression of protumorigenic cytokines and chemokines and enhanced infiltration of innate immune cells, thus triggering the onset of colitis-associated carcinogenesis (CAC) in wild-type mice. Consequently, immunoproteasome-deficient animals (LMP2/MECL-1/LMP7-null mice) were almost completely resistant to CAC development. In patients with ulcerative colitis with high risk for CAC, immunoproteasome-induced protumorigenic mediators were upregulated. In melanoma tumors, the role of immunoproteasomes is relatively unknown. We found that high expression of immunoproteasomes in human melanoma was associated with better prognosis. Similarly, our data revealed that the immunoproteasome has antitumorigenic activity in a mouse model of melanoma. The antitumor immunity against melanoma was compromised in immunoproteasome-deficient mice because of the impaired activity of CD8+ CTLs, CD4+ Th1 cells, and antigen-presenting cells. These findings show that immunoproteasomes may exert opposing roles with either pro- or antitumoral properties in a context-dependent manner.
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