STAT3 Inhibition Attenuates MYC Expression by Modulating Co-Activator Recruitment and Suppresses Medulloblastoma...

Area of Science:

• Pediatric Oncology
• Molecular Biology
• Cancer Genetics

Background:

• Medulloblastoma (MB) is a common childhood brain tumor with high mortality.
• Group 3 MB with MYC amplification is particularly aggressive and therapy-resistant.
• The role of Signal Transducer and Activator of Transcription 3 (STAT3) in MB pathogenesis is not fully understood.

Purpose of the Study:

• To investigate the role of activated STAT3 in promoting MB pathogenesis and chemoresistance.
• To determine if targeting STAT3 can overcome therapy resistance in MYC-amplified MB.
• To explore STAT3 as a therapeutic target for high-risk pediatric MB.

Main Methods:

• Utilized inducible genetic knockdown (KD) and small molecule inhibitors to target STAT3 in MB cells.
• Assessed effects of STAT3 inhibition on MB cell tumorigenic attributes and MYC expression.
• Investigated molecular mechanisms of STAT3-mediated MYC regulation, including p300, BRD4, and RNA Polymerase II (Pol II) occupancy.
• Evaluated STAT3 inhibition in preclinical MB xenograft models (subcutaneous and intracranial).
• Assessed the impact of STAT3 inhibition on cisplatin sensitivity and overall survival in mouse models.

Main Results:

• STAT3 inhibition reduced MB cell survival, proliferation, migration, and stemness.
• Targeting STAT3 decreased MYC oncogene expression and its downstream targets.
• STAT3 inhibition attenuated MYC transcription by affecting p300 recruitment, H3K27 acetylation, BRD4 occupancy, and pSer2-RNAPol II.
• Inhibition of STAT3 signaling significantly reduced MB tumor growth in vivo.
• STAT3 inhibition enhanced MB tumor sensitivity to cisplatin and improved survival in mice.

Conclusions:

• Activated STAT3 promotes MB pathogenesis and chemoresistance by inducing MYC.
• Targeting STAT3 is a promising strategy to reduce tumor growth and overcome therapy resistance in high-risk MB.
• STAT3 inhibition may serve as an effective adjuvant therapy and chemo-sensitizer for pediatric MB patients, improving treatment efficacy and quality of life.