Cotargeting CDK4/6 and BRD4 Promotes Senescence and Ferroptosis Sensitivity in Cancer.

Unlabelled: Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors are approved for breast cancer treatment and show activity against other malignancies, including KRAS-mutant non-small cell lung cancer (NSCLC). However, the clinical efficacy of CDK4/6 inhibitors is limited due to frequent drug resistance and their largely cytostatic effects. Through a genome-wide cDNA screen, we identified that bromodomain-containing protein 4 (BRD4) overexpression conferred resistance to the CDK4/6 inhibitor palbociclib in KRAS-mutant NSCLC cells.

Alanine supplementation exploits glutamine dependency induced by SMARCA4/2-loss.

SMARCA4 (BRG1) and SMARCA2 (BRM) are the two paralogous ATPases of the SWI/SNF chromatin remodeling complexes frequently inactivated in cancers. Cells deficient in either ATPase have been shown to depend on the remaining counterpart for survival. Contrary to this paralog synthetic lethality, concomitant loss of SMARCA4/2 occurs in a subset of cancers associated with very poor outcomes.

SMARCA4/2 loss inhibits chemotherapy-induced apoptosis by restricting IP3R3-mediated Ca flux to mitochondria.

Inactivating mutations in SMARCA4 and concurrent epigenetic silencing of SMARCA2 characterize subsets of ovarian and lung cancers. Concomitant loss of these key subunits of SWI/SNF chromatin remodeling complexes in both cancers is associated with chemotherapy resistance and poor prognosis. Here, we discover that SMARCA4/2 loss inhibits chemotherapy-induced apoptosis through disrupting intracellular organelle calcium ion (Ca) release in these cancers.

Chemogenomic profiling of breast cancer patient-derived xenografts reveals targetable vulnerabilities for difficult-to-treat tumors.

Subsets of breast tumors present major clinical challenges, including triple-negative, metastatic/recurrent disease and rare histologies. Here, we developed 37 patient-derived xenografts (PDX) from these difficult-to-treat cancers to interrogate their molecular composition and functional biology. Whole-genome and transcriptome sequencing and reverse-phase protein arrays revealed that PDXs conserve the molecular landscape of their corresponding patient tumors.

eIF4A Inhibitors Suppress Cell-Cycle Feedback Response and Acquired Resistance to CDK4/6 Inhibition in Cancer.

CDK4/6 inhibitors are FDA-approved drugs for estrogen receptor-positive (ER) breast cancer and are being evaluated to treat other tumor types, including -mutant non-small cell lung cancer (NSCLC). However, their clinical utility is often limited by drug resistance. Here, we sought to better understand the resistant mechanisms and help devise potential strategies to overcome this challenge.