KLF9-dependent ROS regulate melanoma progression in stage-specific manner

Area of Science:

• Oncology
• Molecular Biology
• Dermatology

Background:

• The role of reactive oxygen species (ROS) in melanoma progression is debated, with antioxidants promoting metastasis but their role in earlier stages unclear.
• Genes regulating ROS require functional characterization across all cancer progression stages in mouse models.
• Klf9, a transcriptional regulator of oxidative stress, has not been studied in the context of melanoma progression.

Purpose of the Study:

• To investigate the role of Klf9 and ROS in different stages of melanoma progression using mouse models.
• To determine the functional characterization of Klf9-dependent ROS in melanoma development.
• To explore the therapeutic potential of targeting Klf9-dependent ROS in premalignant melanocytes.

Main Methods:

• Crossed Klf9 knockout mice with Braf^CA (premalignant hyperplasia) and Braf^CA/Pten^-/- (primary melanoma and metastasis) conditional melanocytic mouse models.
• Assessed the impact of Klf9 deficiency on melanocytic hyperplasia, primary tumor formation, growth, and metastasis.
• Treated mice with N-acetyl cysteine (antioxidant) to mimic Klf9 deficiency effects.
• Investigated the mechanistic link between BRAF^V600E, KLF9, ROS, and ERK1/2 signaling pathways.

Main Results:

• Klf9 deficiency inhibited premalignant melanocytic hyperplasia in Braf^CA mice.
• Klf9 deficiency did not affect primary melanoma formation or growth in Braf^CA/Pten^-/- mice but promoted metastasis.
• N-acetyl cysteine treatment phenocopied Klf9 deficiency, suppressing melanocytic hyperplasia.
• BRAF^V600E upregulated KLF9, and KLF9-dependent ROS were crucial for ERK1/2 activation and proliferation in premalignant cells.
• PTEN loss rendered melanomas insensitive to KLF9 and ROS, despite continued ERK1/2 activation.

Conclusions:

• Klf9 plays an essential role in BRAF^V600E signaling in premalignant melanocytes via KLF9-dependent ROS.
• ROS have a variable role in premalignant versus transformed melanocytic cells.
• Targeting Klf9-dependent ROS may offer a novel strategy for suppressing premalignant melanoma growth, potentially through topical antioxidants.