PELP1 is a novel therapeutic target in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths in the United States, with a median survival period of approximately 10 months. There is an urgent need for the development of effective targeted therapies for the treatment of HCC. Proline-, glutamic acid- and leucine-rich protein 1 (PELP1) signaling is implicated in the progression of many cancers, although its specific contribution to the progression of HCC is not yet well understood. Analysis of TCGA HCC gene expression data sets and immunohistochemistry analysis of HCC tissue microarray revealed that HCC tumors had elevated expression of PELP1 compared to normal tissues, and high expression of PELP1 is associated with unfavorable survival outcomes. Suppression of PELP1 expression using shRNA significantly reduced the cell viability, clonogenicity, and invasion of HCC cells. Importantly, SMIP34, a first-in-class small molecule inhibitor targeting PELP1, effectively decreased the cell viability, clonogenic survival and invasiveness of HCC cells. Gene expression analysis using RNA-seq revealed that PELP1-knockdown (KD) cells exhibited a decrease in c-Myc, E2F, and other oncogenic pathways related to HCC. Mechanistic studies showed that SMIP34 treatment impaired the Rix complex, a critical component of ribosomal biogenesis, in HCC cells. Further, the knockdown or pharmacological inhibition of PELP1 significantly decelerated the HCC tumor growth in xenograft models. In summary, our study findings indicate that PELP1 could serve as a promising target for therapeutic intervention in HCC.