Retinoblastoma-binding protein 9 (RBBP9)

Retinoblastoma-binding protein 9 (RBBP9) is a serine hydrolase enzyme identified as a cancer-associated protein with elevated enzymatic activity specifically in various carcinomas, including pancreatic ductal adenocarcinoma. Although RBBP9 protein is present in both normal and tumor tissues, its enzymatic activity is strongly upregulated in neoplastic cells. Molecularly, RBBP9 contains an α/β hydrolase fold and a catalytic triad (Ser75-His165-Asp138) characteristic of serine hydrolases[1][2]. Functionally, it can displace E2F1 from E2F1-Rb complexes, promoting cellular proliferation and overcoming TGF-β-mediated growth inhibition by reducing Smad2/3 phosphorylation. RBBP9 thus acts as a suppressor of TGF-β signaling and is required for maintaining E-cadherin expression and epithelial junction integrity in tumor cells[2]. Elevated RBBP9 activity contributes to anchorage-independent growth and tumorigenesis, making it a promising candidate therapeutic target and biomarker for epithelial cancers[2]. The natural substrate of RBBP9 remains unknown, which poses a challenge for drug development[1][2].

Other names

Serine hydrolase RBBP9BOGRBBP10Protein BOGRBBP-10RBBP-9BogB5T-overexpressed gene proteinRetinoblastoma-binding protein 10putative hydrolase RBBP9retinoma-binding protein 9

Inhibition of TGF-β/Smad-mediated antiproliferative signaling; Promotion of E-cadherin expression and cellular adhesion; Facilitation of anchorage-independent growth of tumor cells