Molecular mechanisms restoring olaparib efficacy through ATR/CHK1 pathway inhibition in olaparib-resistant BRCA1/2(MUT) ovarian cancer models.
Resistance to olaparib inevitably develops in ovarian cancer (OC) patients, highlighting the necessity for effective strategies to improve its efficacy. Here, we established a novel olaparib-resistant patient-derived xenograft model of high-grade serous OC with BRCA1/2 mutations and examined the molecular characteristics of acquired resistance and resensitization to olaparib in treatment-naïve tumors in vivo. Olaparib-resistant xenografts were treated with olaparib, ATR inhibitor (ATRi, ceralasertib), CHK1 inhibitor (CHK1i, MK-8776) or their combinations. Proliferation, apoptosis, ATR/CHK1 activity, PARP signaling, DNA damage response (DDR), epithelial-to-mesenchymal transition (EMT), and MDR1 expression, were examined via RT-qPCR, western blot, and immunohistochemistry. Resistant tumors exhibited defects in PARP and ATR/CHK1 signaling, accompanied by altered expression of proteins involved in DDR and EMT. Olaparib rechallenge combined with ATR/CHK1 inhibitors showed promising synergistic effects on tumor growth inhibition. Mechanistically, combined treatments suppressed tumor proliferation without increasing apoptosis or necrosis, while inducing tumor cell vacuolization indicative of cell death. ATRi combined with olaparib induced or augmented downregulation of ATR, CHK1, PARP1, PARG, BRCA1, γH2AX, and PARylated protein expression, while reversing olaparib-induced upregulation of vimentin, BRCA2, and 53BP1. Our collective findings indicate that ATR/CHK1 pathway inhibition restores the olaparib efficacy in resistant BRCA1/2MUT high-grade serous OC, highlighting promising approach for olaparib rechallenge of non-responsive patients. Uncovered mechanisms might improve our understanding of acquisition and overcoming resistance to olaparib in ovarian cancer.
Biegała Ł
，Statkiewicz M
，Gajek A
，Szymczak-Pajor I
，Rusetska N
，Śliwińska A
，Marczak A
，Mikula M
，Rogalska A
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Identification of plasma miR-4505, miR-4743-5p and miR-4750-3p as novel diagnostic biomarkers for coronary artery disease in patients with type 2 diabetes mellitus: a case-control study.
Type 2 diabetes mellitus (T2DM) and coronary artery disease (CAD) are commonly coexisting clinical entities with still growing incidence worldwide. Recently, circulating microRNAs (miRNAs) have emerged as novel molecular players in cardiometabolic diseases. This study aimed to identify a specific miRNA signature as a candidate biomarker for CAD in T2DM and to delineate potential miRNA-dependent mechanisms contributing to diabetic atherosclerosis.
A total of 38 plasma samples from T2DM patients with and without CAD, CAD patients and healthy controls were collected for expression profiling of 2,578 miRNAs using microarrays. To investigate the regulatory role of differentially expressed (DE)-miRNA target genes, functional annotation and pathway enrichment analyses were performed utilizing multiple bioinformatics tools. Then, protein-protein interaction networks were established leveraging the STRING database in Cytoscape software, followed by cluster analysis and hub gene identification. Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) was carried out for microarray data validation in the larger replication cohort of 94 participants. Receiver operating characteristic analysis was applied to evaluate the diagnostic values of miRNAs. Multivariate logistic regression analysis was used to develop miRNA-based diagnostic models.
In the discovery stage, overexpression of hsa-miR-4505, hsa-miR-4743-5p, hsa-miR-6846-5p, and down-regulation of hsa-miR-3613-3p, hsa-miR-4668-5p, hsa-miR-4706, hsa-miR-6511b-5p, hsa-miR-6750-5p, hsa-miR-4750-3p, hsa-miR-320e, hsa-miR-4717-3p, hsa-miR-7850-5p were detected in T2DM-CAD patients. The DE-miRNA target genes were significantly enriched in calcium ion binding, regulation of actin cytoskeleton, and gene expression. hsa-miR-4505, hsa-miR-4743-5p, and hsa-miR-4750-3p were found to be involved in fatty acid metabolism, leukocyte transendothelial migration, and neurotrophin signaling pathway. Dysregulation of hsa-miR-4505, hsa-miR-4743-5p, and hsa-miR-4750-3p in T2DM-CAD patients compared with T2DM subjects and controls (all p < 0.001) was further confirmed by RT-qPCR. All validated miRNAs demonstrated good discriminatory values for T2DM-CAD (AUC = 0.833-0.876). The best performance in detecting CAD in T2DM was achieved for a combination of three miRNAs (AUC = 0.959, 100% sensitivity, 86.67% specificity).
Our study revealed a unique profile of plasma-derived miRNAs in T2DM patients with CAD. Potential miRNA-regulated pathways were also identified, exploring the underlying pathogenesis of CAD in T2DM. We developed a specific three-miRNA panel of hsa-miR-4505, hsa-miR-4743-5p and hsa-miR-4750-3p, that could serve as a novel non-invasive biomarker for CAD in patients with T2DM.
Szydełko J
，Czop M
，Petniak A
，Lenart-Lipińska M
，Kocki J
，Zapolski T
，Matyjaszek-Matuszek B
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《Cardiovascular Diabetology》
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