Targeting c-Myc: JQ1 as a promising option for c-Myc-amplified esophageal squamous cell carcinoma

Area of Science:

• Oncology
• Molecular Biology
• Cancer Research

Background:

• Esophageal squamous cell carcinoma (ESCC) is often driven by c-Myc amplification, leading to cell cycle dysregulation.
• Currently, no targeted drugs are approved for ESCC, highlighting an unmet clinical need.
• The bromodomain inhibitor JQ1 shows anti-tumor activity in various cancers by targeting c-Myc.

Purpose of the Study:

• To investigate the therapeutic potential of JQ1 in esophageal squamous cell carcinoma (ESCC).
• To elucidate the underlying mechanisms of JQ1's anti-tumor effects in ESCC.
• To evaluate c-Myc amplification as a predictive biomarker for JQ1 therapy in ESCC.

Main Methods:

• In vitro studies assessed JQ1's effects on ESCC cell proliferation, cell cycle, apoptosis, and epithelial-mesenchymal transition.
• Western blot analysis was used to examine the impact of JQ1 on c-Myc, cyclin/Rb, and PI3K/AKT signaling pathways.
• In vivo xenograft models were employed to evaluate JQ1's tumor suppressive efficacy and correlate it with c-Myc expression levels.

Main Results:

• JQ1 demonstrated potent, dose- and time-dependent anti-proliferative effects on ESCC cells.
• JQ1 induced G1 phase cell cycle arrest, apoptosis, and modulated the epithelial-mesenchymal transition.
• JQ1 inactivated c-Myc/cyclin/Rb and PI3K/AKT pathways, evidenced by downregulated c-Myc, cyclin A/E, and phosphorylated Rb, AKT, and S6.
• Tumor suppression was significantly greater in xenografts with high c-Myc expression or amplification compared to those with low expression.

Conclusions:

• Targeting c-Myc with JQ1 exhibits significant anti-tumor activity against ESCC in vitro and in vivo.
• JQ1 effectively inhibits ESCC progression by disrupting cell cycle regulation and inducing apoptosis.
• c-Myc amplification or high expression may serve as a predictive biomarker for JQ1 therapy in ESCC, offering a promising therapeutic strategy.