A SUMOylation-defective MITF germline mutation predisposes to melanoma and renal carcinoma

Area of Science:

• Genetics
• Oncology
• Molecular Biology

Background:

• No common environmental or phenotypic factors link melanoma and renal cell carcinoma (RCC).
• Known risk factors for melanoma include sun exposure and pigmentation, while RCC risks include smoking and obesity.
• A genetic predisposition is suggested by co-occurring melanoma and RCC in patients.

Purpose of the Study:

• To investigate the role of the microphthalmia-associated transcription factor (MITF) in the genetic predisposition to co-occurring melanoma and RCC.
• To identify specific genetic variants within MITF associated with increased cancer risk.

Main Methods:

• Genotyping analysis to identify MITF germline missense substitutions.
• Functional assays to assess the impact of MITF variants on transcription and protein interactions.
• Gene expression profiling and cell-based assays to evaluate tumorigenic potential.

Main Results:

• A germline missense substitution in MITF (Mi-E318K) was found at higher frequency in patients with melanoma, RCC, or both.
• Mi-E318K carriers had a fivefold increased risk for these cancers.
• The mutation impaired MITF SUMOylation, enhanced MITF binding to the HIF1A promoter, and increased its transcriptional activity.
• Mi-E318K promoted cell growth, proliferation, inflammation, clonogenicity, migration, and invasion.

Conclusions:

• The MITF Mi-E318K variant confers a significant genetic predisposition to melanoma and RCC.
• This variant impacts MITF's role in transcription and SUMOylation, contributing to tumorigenesis.
• Findings offer insights into the molecular links between SUMOylation, transcription, and cancer development.