ADRM1

We talk to Vasty Osei Amponsa and Kylie J. Walters about their paper "hRpn13 shapes the proteome and transcriptome through epigenetic factors HDAC8, PADI4, and transcription factor NF-κB p50", their journeys across continents leading them to the NCI, and how Kylie tries to foster curiosity and a sense of belonging in her lab.

Hepatocellular Carcinoma (HCC) is closely linked to inflammatory reactions, with chronic liver diseases acting as major risk factors. In the inflammatory microenvironment, repeated damage and repair of liver cells lead to genetic mutations, abnormal proliferation, and tumorigenesis.

This study aimed to investigate the expression profile of specific cell clusters under inflammatory stimulation in HCC and identify potential therapeutic drugs.

Comprehensive analysis of HCC transcriptome data and single-cell sequencing data from TCGA, ICGC, and GEO databases was conducted to explore the specific molecular mechanisms of epithelial cells. Virtual screening of natural compounds in the ZINC database and in vitro cell experiments were performed to identify drugs that regulate the expression of inflammatory factors in epithelial cells.

Analysis of the single-cell dataset revealed cell clusters closely associated with HCC, notably Epithelial cells, Hepatocytes, MSC, and iPS cells, with Epithelial cells playing a pivotal role in HCC development. Further investigation of TCGA data unveiled 83 differentially expressed genes (DEGs) related to inflammatory responses in HCC. Intersection analysis of DEGs in epithelial cells and HCC DEGs identified 12 common DEGs, including ADRM1, ATP2B1, FZD5, GPC3, KIF1B, KLF6, LY6E, MET, NAMPT, SERPINE1, SPHK1, and SRI. Prognostic analysis revealed that CCL7, GPR132, ITGB8, PTAFR, SELL, and VIP were influential in the survival prognosis of HCC. A prognostic model based on the expression levels of these genes demonstrated an increased risk of HCC associated with higher differential expression of inflammatory response genes. Additionally, molecular dynamics simulations indicated that compounds NADH and Deferoxamine formed stable docking models with the inflammatory protein VIP, suggesting their potential as candidates for targeted therapy.

Inflammatory factors CCL7, GPR132, ITGB8, PTAFR, SELL, and VIP influence the inflammatory cascade response in HCC epithelial cells, and their expression correlates with the survival prognosis of HCC patients. Interfering with VIP expression effectively suppresses proliferation, migration, and invasion of HCC cells, as well as inhibiting the occurrence of inflammatory cascade reactions, thus slowing down the progression of hepatocellular carcinoma. Furthermore, compounds NADH and Deferoxamine have the potential to target and bind to the inflammatory protein VIP, highlighting their relevance in potential HCC treatment.

Targeted protein degradation utilizing a bifunctional molecule to initiate ubiquitination and subsequent degradation by the 26S proteasome has been shown to be a powerful therapeutic intervention. Many bifunctional molecules, including covalent and non-covalent ligands to proteins of interest, have been developed. The traditional target protein degradation methodology targets the protein of interest in both healthy and diseased cell populations, and a therapeutic window is obtained based on the overexpression of the targeted protein. We report here a series of bifunctional degraders that do not rely on interacting with an E3 ligase, but rather a 26S proteasome subunit, which we have named ByeTACs: Bypassing E3 Targeting Chimeras. Rpn-13 is a non-essential ubiquitin receptor for the 26S proteasome. Cells under significant stress or require significant ubiquitin-dependent degradation of proteins for survival, incorporate Rpn-13 in the 26S to increase protein degradation rates. The targeted protein degraders reported here are bifunctional molecules that include a ligand to Rpn-13 and BRD4, the protein of interest we wish to degrade. We synthesized a suite of degraders with varying PEG chain lengths and showed that bifunctional molecules that incorporate a Rpn-13 binder (TCL1) and a BRD4 binder (JQ1) with a PEG linker of 3 or 4 units are the most effective to induce BRD4 degradation. We also demonstrate that our new targeted protein degraders are dependent upon proteasome activity and Rpn-13 expression levels. This establishes a new mechanism of action for our ByeTACs that can be employed for the targeted degradation of a wide variety of protein substrates.