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CRISPR screen identifies autophagy inhibition (GNS561) as a PARP inhibitor (AZD5305) combination strategy in small
Tony Yu1,2, Ranya Barayan1,3, Lifang Song1
1Princess Margaret Cancer Centre, 610 University Ave, Toronto, ON, M5G 2M9, Canada.
Background:
Small cell lung cancer (SCLC) is a deadly cancer with few treatment options and poor prognosis, creating a dire need for improving therapies. Poly (ADP-ribose) polymerase inhibitors (PARPi) have been tested as a treatment strategy, but patient response varies. We aimed to identify novel approaches to sensitize SCLC to PARPi through a genome-wide CRISPR dropout screen.
Methods:
Genome-wide CRISPR dropout screening was conducted in two SCLC cell lines using the PARPi, olaparib, as the selection pressure. Stable shRNA-mediated knockdown cell lines were validated by Western blotting and tested for olaparib sensitivity by assaying for cell viability. Synergy between PARPi and autophagy inhibition was tested by treating SCLC cell lines and analyzing cell viability using SynergyFinder+. The therapeutic strategy combining AZD5305 (PARPi) and GNS561 (novel autophagy inhibitor) was tested in cell line-derived xenograft mouse models.
Results:
CRISPR screening identified the loss of mTOR negative regulators as a mechanism of PARPi sensitivity in SCLC, and knockdown of TSC1 and TSC2 sensitized SCLC cell lines to olaparib. Therapeutic strategies combining PARPi and autophagy inhibition demonstrated synergy in SCLC cell lines, and combination therapy with AZD5305 and GNS561 was effective in cell line-derived xenograft mouse models.
Conclusions:
Autophagy inhibition downstream of the mTOR pathway is a mechanism of PARPi sensitivity in SCLC. This suggests that a therapeutic combination of autophagy inhibition and PARPi is a promising treatment strategy in SCLC, paving the way for the adoption of novel treatments in this disease context.
Insights
Combining poly (ADP-ribose) polymerase inhibitors (PARPi) with autophagy inhibition shows promise for treating small cell lung cancer (SCLC). This strategy enhances PARPi sensitivity by targeting the mTOR pathway, offering new therapeutic avenues for SCLC patients.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Therapeutics
Background:
- Small cell lung cancer (SCLC) presents a significant clinical challenge due to limited treatment options and poor prognosis.
- Poly (ADP-ribose) polymerase inhibitors (PARPi) show variable efficacy in SCLC, necessitating strategies to enhance patient response.
- Identifying novel approaches to sensitize SCLC to PARPi is crucial for improving therapeutic outcomes.
Purpose of the Study:
- To identify novel mechanisms and therapeutic strategies to sensitize small cell lung cancer (SCLC) to poly (ADP-ribose) polymerase inhibitors (PARPi).
- To explore the role of autophagy inhibition in enhancing PARPi sensitivity in SCLC.
- To evaluate the efficacy of combining PARPi with autophagy inhibitors in preclinical SCLC models.
Main Methods:
- Genome-wide CRISPR dropout screens were performed in SCLC cell lines under olaparib selection pressure.
- Knockdown of identified genes (e.g., TSC1, TSC2) was validated, and their effect on olaparib sensitivity was assessed.
- Synergy between PARPi and autophagy inhibition was evaluated using SynergyFinder+, and combination therapy was tested in xenograft mouse models.
Main Results:
- CRISPR screening revealed that loss of mTOR negative regulators confers PARPi sensitivity in SCLC.
- Knockdown of TSC1 and TSC2 significantly sensitized SCLC cell lines to olaparib.
- Combination therapy with a PARPi (AZD5305) and an autophagy inhibitor (GNS561) demonstrated synergistic effects and efficacy in preclinical SCLC models.
Conclusions:
- Autophagy inhibition, downstream of the mTOR pathway, represents a key mechanism for enhancing PARPi sensitivity in SCLC.
- The combination of PARPi and autophagy inhibition presents a promising therapeutic strategy for SCLC.
- This study supports the development of novel combination treatments for SCLC, potentially improving patient prognosis.
