Abstract PR009: Linking VHL and SETD2 in a common oncogenic pathway that converges on the mitotic spindle

Abstract

Abstract Loss of chromosome 3p is a landmark event in clear cell renal cell carcinoma (ccRCC) that results in mono-allelic loss of VHL (von Hippel Lindau) and SETD2 (Set-domain containing 2) (and other tumor suppressors co-located on 3p). Second hits in VHL inactivate this key tumor suppressor initiating tumor progression. SETD2, a histone methyltransferase, was previously shown to have a dual function in methylating both histones and microtubules, thereby contributing to both the histone and tubulin codes. Methylation by SETD2 on microtubules occurs at the mitotic spindle and is essential for normal mitosis and cytokinesis, with loss of SETD2 acting as a strong driver of apoptosis. This raises a conundrum of how cancer cells survive early mono-allelic loss of SETD2, escaping cell death. We have identified the mitotic kinase, Aurora kinase A (AURKA), as a regulator of SETD2. Our data uncover SETD2 as a unique substrate for phosphorylation by AURKA, with mass spectrometry identifying serine 2080 (S2080) as the site of phosphorylation on SETD2. Phospho-SETD2 (S2080) localized at the spindle poles during mitosis, and this specific localization was modulated by AURKA enzymatic activity. Initial observations reveal a role for AURKA driven SETD2 phosphorylation at S2080 in nucleocytoplasmic shuttling of this methyltransferase. Our data suggest that phosphorylation of SETD2 by AURKA contributes to both its methyltransferase (i.e. enzymatic) activity and its geo-spatial location with the cell. Importantly, AURKA expression levels are high in VHL-null cells resulting from an inability of VHL to target AURKA for degradation and our data now highlight a direct link between VHL and SETD2, two tumor suppressors believed to independently drive RCC pathogenesis. In summary, our data reveal a tumor-specific vulnerability linked to mitotic fragility that can be precisely targeted to ultimately drive mitotic catastrophe. Citation Format: Ruhee Dere, Pratim Chowdhury, Sung Yun Jung, Rim Aboulhassane, Manga Motrapu, Xiaoli Wang, Richard Han, Cheryl Walker, Ian Frew, W. Kimryn Rathmell. Linking VHL and SETD2 in a common oncogenic pathway that converges on the mitotic spindle [abstract]. In: Proceedings of the AACR Special Conference: Advances in Kidney Cancer Research; 2023 Jun 24-27; Austin, Texas. Philadelphia (PA): AACR; Cancer Res 2023;83(16 Suppl):Abstract nr PR009.