HPK1 Dysregulation-Associated NK Cell Dysfunction and Defective Expansion Promotes Metastatic Melanoma Progression

Area of Science:

• Immunology
• Cancer Biology
• Molecular Medicine

Background:

• Distant metastasis is the primary cause of cancer mortality, controlled by immune surveillance.
• Natural killer (NK) cells are crucial in preventing metastasis, but their dysfunction during this process is not fully understood.
• The molecular mechanisms linking NK cell dysfunction to cancer metastasis remain elusive.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying NK cell dysfunction in cancer metastasis.
• To investigate the role of MAP4K1 (encoding HPK1) in regulating NK cell function and metastasis.
• To explore HPK1 as a potential therapeutic target for enhancing anti-metastatic immunity.

Main Methods:

• Analysis of HPK1 expression in dysfunctional NK cells from peripheral blood and metastatic sites.
• Utilizing conditional HPK1 overexpression and MAP4K1-deficient mouse models to study melanoma metastasis.
• Assessing NK cell cytotoxicity, expansion, and activation in response to HPK1 modulation.
• Correlating HPK1 levels with TGF-β1 signaling and patient response to immune checkpoint therapy.

Main Results:

• Aberrant overexpression of MAP4K1 (HPK1) was observed in dysfunctional NK cells.
• HPK1 overexpression exacerbated melanoma lung metastasis in mice, while MAP4K1 deficiency conferred resistance.
• HPK1 was found to restrain NK cell cytotoxicity and expansion by inhibiting activating receptors.
• HPK1 limits human NK cell activation and is linked to NK cell dysfunction in melanoma, correlating with TGF-β1 and immunotherapy response.

Conclusions:

• HPK1 acts as an intracellular checkpoint that restrains NK cell anti-tumor responses.
• Tumors dysregulate and hijack HPK1 during metastatic progression to evade NK cell surveillance.
• Targeting HPK1 represents a promising strategy to enhance NK cell-mediated anti-metastatic immunity and improve cancer immunotherapy outcomes.