I-BET726 suppresses human skin squamous cell carcinoma cell growth in vitro and in vivo

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Skin squamous cell carcinoma (SCC) is a prevalent malignancy.
• Bromodomain-containing protein 4 (BRD4) is implicated as a therapeutic target in SCC.
• Novel therapeutic agents targeting BRD4 are needed for SCC treatment.

Purpose of the Study:

• To investigate the efficacy of I-BET726, a novel BRD4 inhibitor, against human skin SCC cells.
• To elucidate the molecular mechanisms underlying I-BET726's anti-cancer effects.
• To evaluate the in vivo therapeutic potential of I-BET726 in a skin SCC xenograft model.

Main Methods:

• In vitro studies using established and primary human skin SCC cell lines.
• Assessment of cell survival, proliferation, cell cycle, migration, and apoptosis.
• Western blot analysis to evaluate protein expression (BRD4-regulated proteins, SphK1, Akt).
• In vivo efficacy study using A431 xenograft model in immunodeficient mice.

Main Results:

• I-BET726 potently inhibited SCC cell survival, proliferation, cell cycle progression, and migration.
• I-BET726 induced significant apoptosis and demonstrated greater efficacy than existing BRD4 inhibitors.
• I-BET726 downregulated BRD4-regulated proteins (c-Myc, Bcl-2, cyclin D1) and inhibited SphK1 and Akt signaling.
• Restoring Akt activation partially reduced I-BET726-induced cytotoxicity.
• Oral administration of I-BET726 significantly inhibited tumor growth in vivo.

Conclusions:

• I-BET726 exhibits potent anti-cancer activity against skin SCC cells in vitro and in vivo.
• I-BET726 exerts its effects by downregulating BRD4-regulated proteins and inhibiting SphK1-Akt signaling pathways.
• I-BET726 represents a promising therapeutic candidate for the treatment of skin SCC.