Targeting BRD4 in gastric cancer: promoting apoptosis and suppressing tumor progression

The MYC pathway is highly activated in gastric cancer (GC), but the MYC oncogene's structural biology makes direct pharmacological inhibition very difficult. We hypothesized that BRD4, as a major co-activator of MYC, maintains MYC-dependent survival circuits, thus making BRD4 a key therapeutic vulnerability in late GC.

We carried out a comprehensive transcriptomic analysis by utilizing large-scale data sets from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO), then these computational forecasts were later verified in strict clinical cohorts via molecular and histological methods. Functional verification was done through genetic and pharmacological interference by means of CRISPR-Cas9 gene deletion and PROTAC-induced protein breakdown with ARV771, ultimately, the therapeutic efficacy and systemic safety of these interventions were assessed in vivo with mouse xenograft models.

Our analyses revealed that the expression of BRD4 was significantly increased in GC tissues and there was a strong connection between this increase and the MYC hyperactivation, advanced TNM staging, and shortened patient survival. Our knockout (KO) experiments found that the viability of tumor cells depended greatly on the BRD4 - MYC - BCL2 signaling pathway because when BRD4 was depleted, the expression of BCL2, a crucial anti-apoptotic protein, decreased substantially. When pharmacological intervention was applied using ARV771, these cancer-related characteristics were effectively reversed, resulting in the suppression of tumor proliferation, the decrease of BCL2 levels, and significant inhibition of the growth of xenograft tumors in vivo without observable toxicity.

Our findings suggest that BRD4 acts a chief epigenetic controller which promotes the progress of GC by intensifying MYC-dependent survival and ARV771 blocks this survival advantage, thus presenting a highly compelling rationale for integrating BRD4 degraders into modern targeted regimens.