CDK12 is hyperactivated and a synthetic-lethal target in BRAF-mutated melanoma

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Melanoma is an aggressive skin cancer with inherent resistance to chemotherapy.
• Mutations activating the RAS/mitogen-activated protein kinase (MAPK) pathway are common in melanoma and linked to drug resistance.
• The precise mechanisms by which the RAS/MAPK pathway confers drug resistance remain incompletely understood.

Purpose of the Study:

• To investigate the role of cyclin-dependent kinase 12 (CDK12) in melanoma drug resistance.
• To explore the regulatory relationship between the RAS/MAPK pathway and CDK12 activity.
• To identify potential therapeutic strategies by targeting CDK12 and related pathways in melanoma.

Main Methods:

• Analysis of CDK12 activity in melanoma cells.
• Investigating the effect of CDK12 inhibition on gene expression, focusing on gene length and exon count.
• Evaluating the impact of CDK12 inhibition on DNA repair genes, growth-promoting genes, and transcription factors AP-1 and NF-κB.
• Assessing the synergistic effects of CDK12 inhibitors with inhibitors of AP-1 and NF-κB pathways on melanoma cell growth.

Main Results:

• Melanoma cells exhibit constitutively high CDK12 activity.
• CDK12 inhibition leads to decreased expression of long, multi-exonic genes, including DNA repair genes.
• CDK12 inhibition promotes the expression of short, few-exonic genes, including AP-1 and NF-κB regulated growth genes.
• Combined inhibition of CDK12 and AP-1/NF-κB pathways synergistically suppresses melanoma growth.

Conclusions:

• The RAS/MAPK pathway regulates CDK12 activity in melanoma.
• CDK12 plays a critical role in maintaining genomic stability by regulating the expression of DNA repair genes.
• Targeting CDK12, particularly in combination with inhibitors of AP-1 and NF-κB, presents a promising therapeutic approach for overcoming chemotherapy resistance in melanoma.