JQ1, a BET‐bromodomain inhibitor, inhibits human cancer growth and suppresses PD‐L1 expression

Most traditional cytotoxic chemotherapeutic agents have poor aqueous solubility and significant toxicity. Hence, there is a need to develop molecule-targeted drugs. Programmed death-ligand 1 (PD-L1) is associated with the prognosis of several cancer types, and blockade of PD-1/PD-L1 signaling increases the amplitude of anti-tumor immunity. In the present study, we investigated the effects of JQ1, a bromodomain and extraterminal-bromodomain inhibitor, on cell growth, and messenger RNA (mRNA) and protein levels of PD-L1 in renal cell carcinoma primary culture cells, and prostate, liver, and lung cancer cell lines. The results of the cell counting kit-8 assay suggested that JQ1 inhibits cell growth in a dose-dependent manner. The mRNA and protein levels of PD-L1 decreased in the primary culture of JQ1-treated renal carcinoma, prostate cancer, liver cancer, and lung cancer cell lines. In addition, the mRNA level of PD-L2 also decreased in the JQ1-treated cells. Overall, JQ1 might be a potential anti-tumor agent.