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Secretogranin II influences the assembly and function of MHC class I in melanoma
Tamara Steinfass1,2,3,4, Juliane Poelchen1,2,3,4, Qian Sun1,2,3,4
1Skin Cancer Unit, German Cancer Research Center (DKFZ), INF 280, 69120, Heidelberg, Germany.
Abstract:
Melanoma is the deadliest form of skin cancer showing rising incidence over the past years. New insights into the mechanisms of melanoma progression contributed to the development of novel treatment options, such as immunotherapies. However, acquiring resistance to treatment poses a big problem to therapy success. Therefore, understanding the mechanisms underlying resistance could improve therapy efficacy. Correlating expression levels in tissue samples of primary melanoma and metastases revealed that secretogranin 2 (SCG2) is highly expressed in advanced melanoma patients with poor overall survival (OS) rates. By conducting transcriptional analysis between SCG2-overexpressing (OE) and control melanoma cells, we detected a downregulation of components of the antigen presenting machinery (APM), which is important for the assembly of the MHC class I complex. Flow cytometry analysis revealed a downregulation of surface MHC class I expression on melanoma cells that showed resistance towards the cytotoxic activity of melanoma-specific T cells. IFNγ treatment partially reversed these effects. Based on our findings, we suggest that SCG2 might stimulate mechanisms of immune evasion and therefore be associated with resistance to checkpoint blockade and adoptive immunotherapy.
Insights
Secretogranin 2 (SCG2) promotes immune evasion in melanoma by downregulating antigen presentation machinery, leading to resistance against immunotherapies like checkpoint blockade.
Area of Science:
- Oncology
- Immunology
- Molecular Biology
Background:
- Melanoma incidence is rising, necessitating novel treatment strategies like immunotherapy.
- Treatment resistance remains a significant challenge in melanoma therapy, hindering patient outcomes.
- Understanding resistance mechanisms is crucial for improving the efficacy of current and future melanoma treatments.
Discussion:
- Secretogranin 2 (SCG2) is highly expressed in advanced melanoma, correlating with poor overall survival.
- SCG2 overexpression in melanoma cells leads to the downregulation of antigen-presenting machinery (APM) components.
- This downregulation results in reduced surface MHC class I expression, impairing T cell recognition and cytotoxic activity.
Key Insights:
- SCG2 expression is linked to immune evasion in melanoma.
- Melanoma cells resistant to T cell-mediated killing exhibit decreased MHC class I surface expression.
- Interferon-gamma (IFNγ) partially restores MHC class I expression, suggesting a potential therapeutic avenue.
Outlook:
- SCG2 may drive resistance to immune checkpoint blockade and adoptive immunotherapy in melanoma.
- Targeting SCG2 or restoring APM function could overcome treatment resistance.
- Further research into SCG2's role in immune evasion is warranted to develop more effective melanoma therapies.
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