DHHC3 interferes with antitumor immunity in melanoma cells

Area of Science:

• Oncology
• Immunology
• Cell Biology

Background:

• The protein-acyltransferase DHHC3 is implicated in tumor malignancies, but its precise mechanisms remain poorly understood.
• Understanding DHHC3's role is crucial for developing novel melanoma therapies.

Purpose of the Study:

• To investigate the role of DHHC3 in melanoma growth, oxidative stress, senescence, and anti-melanoma immunity.
• To determine if DHHC3 influences melanoma cell invasion and metastasis independently of the immune system.

Main Methods:

• Utilized DHHC3-null B16F10 melanoma cells in immunocompetent C57/BL6 and immunodeficient NOD-SCID mice.
• Assessed tumor growth, oxidative stress, senescence markers, and immune cell infiltration (M1/M2 macrophages, NK cells, T cells, MDSCs).
• Evaluated experimental metastasis following cell injection into mice.

Main Results:

• DHHC3-null melanoma cells exhibited increased oxidative stress and senescence, leading to diminished tumor growth in immunocompetent mice.
• Tumor growth reduction was dependent on the immune system, as DHHC3-null cells did not show decreased growth in immunodeficient mice.
• DHHC3-null melanomas showed increased anti-tumor immune cells (M1 macrophages, NK, CD4+T, CD8+T) and decreased pro-tumor cells (M2 macrophages, MDSCs).
• DHHC3 ablation had minimal impact on experimental melanoma metastasis in both immunocompetent and immunodeficient mice.

Conclusions:

• DHHC3 ablation enhances anti-melanoma immunity by promoting oxidative stress and senescence, thereby increasing anti-tumor immune cell populations.
• DHHC3 primarily controls primary melanoma growth through immune modulation, not by directly affecting intrinsic cell growth or metastatic potential.
• Targeting DHHC3 could be a therapeutic strategy to bolster anti-melanoma immune responses.