Chromatin accessibility is critical for
tumor development, whose mechanisms remain unclear. As a crucial regulator for chromatin remodeling, BRD4 promotes
tumor progression by regulating multiple genes. As a small-molecule inhibitor of BRD4, JQ1 has potent chemotherapeutic activity against various human
cancers. However, whether JQ1 has potential anti-
tumor effects and how JQ1 regulates global transcription in
gastric cancer (GC) remain largely unknown. In this research, we found BRD4 was highly expressed in GC tissues and was significantly associated with poor prognosis. JQ1 inhibited the proliferation and induced apoptosis of GC cells in vitro. Besides, JQ1 suppressed the migration and invasion of
cancer cells by inducing MET. Notably, an assay for
transposase-accessible
chromatin using sequencing (ATAC-seq) data showed that JQ1 obviously downregulated the
chromatin accessibility of GC cells and differentially accessible regions were highly enriched for RUNX2-binding motifs. Combinational analysis of ATAC-seq and
RNA-seq data discovered NID1 as the downstream target of JQ1 and JQ1 reduced NID1 expression in GC cells.
Chromatin immunoprecipitation,
luciferase reporter gene assay, and rescue experiments all confirmed that RUNX2/NID1 axis was responsible for JQ1-inhibiting
metastasis of GC cells. What's more, high expression of NID1 in GC tissues also predicted poor survival outcome of
cancer patients and NID1 knockdown prohibited migration and invasion of
cancer cells via partially inducing MET. Finally, in vivo models showed that JQ1 prevented GC growth and suppressed
cancer metastasis. In conclusion, JQ1 inhibits the malignant progression of GC by downregulating
chromatin accessibility and inactivating RUNX2/NID1 signaling. In addition, NID1 is also a novel therapeutic target for progressive GC patients.