posted on 2023-03-31, 01:46authored byTatiana Shorstova, Maud Marques, Jie Su, Jake Johnston, Claudia L. Kleinman, Nancy Hamel, Sidong Huang, Moulay A. Alaoui-Jamali, William D. Foulkes, Michael Witcher
Table S1: List of shRNA plasmids. Table S2: List of primers S3: Mutations in ovarian and lung cancer cell lines.
Funding
Canadian Institute for Health
Quebec Breast Cancer Foundation
Department of Defense
Canadian Cancer Society Research Institute
Chercheur Boursier
History
ARTICLE ABSTRACT
The antitumor activity of bromodomain and extraterminal motif protein inhibitors (BETi) has been demonstrated across numerous types of cancer. As such, these inhibitors are currently undergoing widespread clinical evaluation. However, predictive biomarkers allowing the stratification of tumors into responders and nonresponders to BETi are lacking. Here, we showed significant antiproliferative effects of low dosage BETi in vitro and in vivo against aggressive ovarian and lung cancer models lacking SMARCA4 and SMARCA2, key components of SWI/SNF chromatin remodeling complexes. Restoration of SMARCA4 or SMARCA2 promoted resistance to BETi in these models and, conversely, knockdown of SMARCA4 sensitized resistant cells to BETi. Transcriptomic analysis revealed that exposure to BETi potently downregulated a network of genes involved in receptor tyrosine kinase (RTK) signaling in SMARCA4/A2-deficient cells, including the oncogenic RTK HER3. Repression of signaling downstream of HER3 was found to be an important determinant of response to BETi in SMARCA4/A2-deficient cells. Overall, we propose that BETi represent a rational therapeutic strategy in poor-prognosis, SMARCA4/A2-deficient cancers.
These findings address an unmet clinical need by identifying loss of SMARCA4/A2 as biomarkers of hypersensitivity to BETi.