LSD1 inhibitor, TAS1440, disrupts INSM1-LSD1 complex activating tumor-suppressive pathways via transcriptional...

Area of Science:

• Oncology
• Epigenetics
• Molecular Biology

Background:

• Small cell lung cancer (SCLC) is an aggressive malignancy with limited therapeutic options.
• Lysine-specific histone demethylase 1A (LSD1) plays a crucial role in maintaining the neuroendocrine phenotype of SCLC by repressing NOTCH and TGF-β signaling.
• Understanding LSD1 inhibition mechanisms and chemoresistance is vital for developing novel SCLC treatments.

Purpose of the Study:

• To develop a novel, specific, and safe LSD1 inhibitor for SCLC treatment.
• To elucidate the mechanism of action of the developed inhibitor, TAS1440.
• To evaluate the efficacy of TAS1440 in preclinical SCLC models.

Main Methods:

• Structure-based drug design was employed to engineer TAS1440, a non-covalent, H3-competitive LSD1 inhibitor.
• TAS1440's effects on proliferation and differentiation were assessed in SCLC cell lines (INSM1/ASCL1-high SCLC-A).
• Tumor regression was evaluated in SCLC xenograft models. Mechanistic studies involved assessing LSD1 activity, histone marks, and transcription factor activation (INSM1, SMAD2).

Main Results:

• TAS1440 demonstrated specificity and reduced off-target effects compared to existing inhibitors.
• TAS1440 suppressed proliferation in SCLC-A cells and induced significant tumor regression in vivo.
• The inhibitor functions via dual mechanisms: inhibiting LSD1 activity and disrupting LSD1-repressive complexes, leading to the reactivation of INSM1 and SMAD2 and subsequent reprogramming of TGF-β/NOTCH signaling.

Conclusions:

• TAS1440 represents a promising next-generation epigenetic therapy candidate for SCLC, particularly for INSM1-high SCLC-A.
• The study defines the mode of action and chemoresistance mechanisms related to LSD1 and INSM1.
• TAS1440's ability to reprogram tumor-suppressive signaling pathways offers a novel therapeutic strategy for SCLC.