Antagonizing STAT3 activation with benzo[b]thiophene 1, 1-dioxide based small molecules

Area of Science:

• Oncology
• Medicinal Chemistry
• Molecular Biology

Background:

• Signal Transducer and Activator of Transcription 3 (STAT3) is a key target in cancer therapy.
• Existing STAT3 inhibitors lack sufficient potency and druggability for clinical use.

Purpose of the Study:

• To design, synthesize, and evaluate novel aminobenzo[b]thiophene 1,1-dioxides as potential STAT3 inhibitors for cancer treatment.
• To identify potent compounds with favorable drug-like properties and assess their antitumor efficacy.

Main Methods:

• Synthesis of a series of aminobenzo[b]thiophene 1,1-dioxide derivatives.
• In vitro evaluation of STAT3 inhibition, including IC50 determination against various cancer cell lines.
• Assessment of compound effects on STAT3 phosphorylation, downstream targets (Bcl-2), and upstream kinases (Src, Jak2).
• Analysis of reactive oxygen species (ROS) levels, apoptosis induction, colony formation, and bypass kinase (p-Erk) activity.
• In vivo antitumor efficacy and toxicity studies.

Main Results:

• Several synthesized compounds displayed significant antitumor activity, outperforming the reference inhibitor Stattic.
• Compound 15 emerged as the most potent STAT3 inhibitor, with IC50 values ranging from 0.33-0.75 μM.
• Compound 15 effectively inhibited both overexpressed and IL-6-induced STAT3 phosphorylation without affecting Src or Jak2.
• Compound 15 suppressed Bcl-2 expression, increased ROS levels, induced apoptosis, and inhibited colony formation in cancer cells.
• In vivo studies showed Compound 15 induced significant antitumor responses with lower toxicity compared to Doxorubicin.

Conclusions:

• Aminobenzo[b]thiophene 1,1-dioxides represent a promising class of novel STAT3 inhibitors.
• Compound 15 demonstrates potent and selective STAT3 inhibition with significant in vitro and in vivo antitumor efficacy and favorable safety profile.
• These findings support the further development of Compound 15 as a potential therapeutic agent for cancer treatment.