Inhibition of GCN2 Reveals Synergy with Cell-Cycle Regulation and Proteostasis

Area of Science:

• Cellular biology
• Cancer research
• Molecular signaling

Background:

• The integrated stress response (ISR) is a cellular network that regulates protein synthesis in response to various stressors.
• GCN2, a key component of the ISR, senses amino acid deficiency and plays a role in maintaining homeostasis.
• GCN2 inhibition is a potential cancer therapy, especially when combined with other treatments.

Purpose of the Study:

• To identify drugs that synergize with the GCN2 inhibitor TAP20.
• To evaluate the efficacy of combined GCN2 inhibition and other drug classes in cancer cell lines.
• To investigate the impact of these combinations on cell growth and invasion.

Main Methods:

• Screening of 25 compounds for synergy with TAP20 in six cancer cell lines.
• Assessment of cell growth inhibition and synergy analyses.
• Matrix-dependent invasion assays to evaluate anti-invasive effects.

Main Results:

• Several drug classes, including proteostasis inhibitors, MEK-ERK pathway inhibitors, and pan-CDK inhibitors (flavopidridol, seliciclib), showed potent synergy with TAP20.
• CDK7 was identified as a common target, with the selective CDK7 inhibitor THZ-1 also synergizing with TAP20.
• Combinations demonstrated partial synergy in invasion assays, while TAP20 alone inhibited invasion at sub-lethal concentrations.

Conclusions:

• GCN2 inhibition, particularly with TAP20, is a promising strategy for cancer therapy.
• Combinations targeting GCN2 and pathways like CDK7 or proteostasis warrant further investigation.
• GCN2 inhibition may have direct anti-invasive effects relevant to cancer treatment.