KMT2C methyltransferase domain regulated INK4A expression suppresses prostate cancer metastasis

Frequent truncating mutations of the histone lysine N‑methyltransferase KMT2C have been detected by whole exome sequencing studies in various cancers, including malignancies of the prostate. However, the biological consequences of these alterations in prostate cancer have not yet been elucidated. To investigate the functional impact of these mutations we deleted the C-terminal catalytic core motif of KMT2C specifically in the prostate epithelium of mice. We show here that impaired KMT2C methyltransferase activity drives proliferation and, when combined with loss of the tumour suppressor PTEN, triggers metastatic dissemination and reduces life expectancy. In our model system and human prostate cancer samples we show that KMT2C-mutated tumours activate the proliferative MYC signalling axis and fail to express the oncogene-induced cell cycle repressor p16INK4A. In addition, we observe a striking reduction in disease-free survival of patients with KMT2C-mutated prostate cancer. Thus, we identify truncated KMT2C as a driver of aggressive prostate cancer. mRNA expression profiles of prostate epithelial cells derived from 19-week-old mice with prostate specific deletion of Pten (P), Kmt2c SET domain (K), both (D) or neither (W).