Developing a prognostic model for hepatocellular carcinoma based on MED19 and clinical stage and determining MED19 as a therapeutic target.

Backgroud: Mediator complex subunit 19 (MED19), a member of the mediator complex, has been demonstrated to involve in tumorigenesis of hepatocellular carcinoma (HCC). However, the regulation mechanisms of MED19, the immune landscape linking MED19 to HCC and its predictive value of immunotherapy treatment in HCC are so far unknown.

Methods: Here, we analyzed data from The Cancer Genome Atlas and other databases to assess the expression of MED19 and its prognosis and therapeutical-targets impact in HCC.

Results: MED19 expression was upregulated in HCC tissues compared to non-tumorous liver tissues and that its upregulation was positively associated with advanced clinicopathology features. The multivariate analysis showed that MED19 was an independent predictor of outcome in HCC. In vitro experiments revealed that MED19 knockdown suppressed hepG2 cells proliferation, colony forming and invasion and induced apoptosis. Furthermore, MED19 inhibition resulted in G0/G1 phase arrest in hepG2 cells. We screened differentially expressed genes between low and high MED19 expression groups. Enrichment analyses showed that these genes were mainly linked to nuclear division and cell cycle. The pattern of tumor-infiltrating immune was demonstrated to be related with MED19 expression in HCC. TIDE analyses showed that patients in the low-expression group presented significantly better immunotherapy. Moreover, we developed a predicted model for HCC patient's prognosis. Receiver operating characteristic analyses revealed that this model processed a favorable performance in predicting the prognosis of HCC patients. Finally, a nomogram was built for predicting survival probability of individual HCC patient.

Conclusion: These findings suggest that MED19 as a novel biomarker that has significant association with immune landscape and immunotherapy response in HCC. The proposed prediction model composed of MED19 and pathological stage has a better role in determining prognosis and stratifying of HCC.