A triple action CDK4/6-PI3K-BET inhibitor with augmented cancer cell cytotoxicity.
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ABSTRACT:
SUBMITTER: Burgoyne AM
PROVIDER: S-EPMC7385619 | biostudies-literature |
REPOSITORIES: biostudies-literature
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| S-EPMC10259662 | biostudies-literature
Project description:BET inhibitors are promising therapeutic agents for the treatment of triple-negative breast cancer (TNBC), but the rapid emergence of resistance necessitates investigation of combination therapies and their effects on tumor evolution. Here, we show that palbociclib, a CDK4/6 inhibitor, and paclitaxel, a microtubule inhibitor, synergize with the BET inhibitor JQ1 in TNBC lines. High-complexity DNA barcoding and mathematical modeling indicate a high rate of de novo acquired resistance to these drugs relative to pre-existing resistance. We demonstrate that the combination of JQ1 and palbociclib induces cell division errors, which can increase the chance of developing aneuploidy. Characterizing acquired resistance to combination treatment at a single cell level shows heterogeneous mechanisms including activation of G1-S and senescence pathways. Our results establish a rationale for further investigation of combined BET and CDK4/6 inhibition in TNBC and suggest novel mechanisms of action for these drugs and new vulnerabilities in cells after emergence of resistance.
| S-EPMC7214447 | biostudies-literature
Project description:PI3K and CDK4/6 inhibitors (CDK4/6i) are targeted therapies approved to treat advanced breast cancer; CDK4/6is are more widely used. Here, we discuss trials that examine PI3K inhibitors with novel drug combinations, including a CDK4/6i, given data implicating the pathway in CDK 4/6 resistance.See related articles by Lu et al., p. 408, and Tolaney et al., p. 418.
| S-EPMC8278622 | biostudies-literature
Project description:PURPOSE:In thyroid cancer clinical trials, agents targeting VEGF receptors (VEGFR) and RET, among other kinases, have led to partial responses but few complete or durable responses. The RAF-MEK-ERK and PI3K-AKT-mTOR signaling pathways are frequently activated in differentiated and medullary thyroid cancer (DTC and MTC) and may provide therapeutic targets for these diseases. We tested a novel drug combination targeting RAF, phosphoinositide 3-kinase (PI3K), and mTOR, plus VEGFR2 and RET, in thyroid cancer preclinical models with defined genetic backgrounds. EXPERIMENTAL DESIGN:RAF265, an ATP-competitive pan-RAF inhibitor active against VEGFR2, and BEZ-235, a PI3K inhibitor also active against Torc1 and Torc2, were tested alone and in combination in a panel of thyroid cancer lines. We tested RAF265 and BEZ-235 for kinase inhibition, growth inhibition and cell-cycle alterations, and inhibition of signaling targets and tumor growth in xenograft models. RESULTS:Both drugs potently inhibited their kinase targets in the extracellular signal-regulated kinase (ERK) and PI3K pathways. In addition, RAF265 had significant RET inhibitory activity (IC?? = 25-50 nmol/L for RET(C634W)). The combination strongly inhibited proliferation of DTC and MTC cell lines with mutations in RAS, BRAF, PTEN, and RET. Synergy was shown for B-CPAP (BRAF(V600E)) and TT cells (RET(C634W)). The combination of both drugs significantly inhibited growth of CAL62 (KRAS(G12R/G12R)) and TT xenografts, thoroughly inhibiting ERK and PI3K pathway signaling. CONCLUSIONS:Combined blockade of ERK and PI3K signaling potently inhibits growth in preclinical models representing the key genotypes seen in refractory thyroid cancer. These targets and therapies are promising for further development in both differentiated and medullary thyroid cancers.
| S-EPMC4828042 | biostudies-literature
Project description:Poly(ADP-ribose) polymerase inhibitors (PARPis) induce DNA lesions that preferentially kill homologous recombination (HR)-deficient breast cancers induced by BRCA mutations, which exhibit a low incidence in breast cancer, thereby limiting the benefits of PARPis. Additionally, breast cancer cells, particularly triple-negative breast cancer (TNBC) cells, exhibit HR and PARPi resistance. Therefore, targets must be identified for inducing HR deficiency and sensitizing cancer cells to PARPis. Here, we reveal that CXorf56 protein increased HR repair in TNBC cells by interacting with the Ku70 DNA-binding domain, reducing Ku70 recruitment and promoting RPA32, BRCA2, and RAD51 recruitment to sites of DNA damage. Knockdown of CXorf56 protein suppressed HR in TNBC cells, specifically during the S and G2 phases, and increased cell sensitivity to olaparib in vitro and in vivo. Clinically, CXorf56 protein was upregulated in TNBC tissues and associated with aggressive clinicopathological characteristics and poor survival. All these findings indicate that treatment designed to inhibit CXorf56 protein in TNBC combined with PARPis may overcome drug resistance and expand the application of PARPis to patients with non-BRCA mutantion.
| S-EPMC10167262 | biostudies-literature
Project description:The development of castration-resistant prostate cancer (CRPC) is a significant factor that reduces life expectancy among patients with prostate cancer. Previously, it is reported that CDK4/6 inhibitors can overcome the resistance of CRPC to BET inhibitors by destabilizing BRD4, suggesting that the combination of CDK4/6 inhibitors and BET inhibitors is a promising approach for treating CRPC. In this study, candidates that affect the combined antitumor effect of CDK4/6 inhibitors and BET inhibitors on CRPC is aimed to examine. The data demonstrates that CBX3 is abnormally upregulated in CDK4/6 inhibitors-resistant cells. CBX3 is almost positively correlated with the cell cycle in multiple malignancies and is downregulated by BET inhibitors. Mechanistically, it is showed that CBX3 is transcriptionally upregulated by BRD4 in CRPC cells. Moreover, it is demonstrated that CBX3 modulated the sensitivity of CRPC to CDK4/6 inhibitors by binding with RB1 to release E2F1. Furthermore, it is revealed that PLK1 phosphorylated CBX3 to enhance the interaction between RB1 and CBX3, and desensitize CRPC cells to CDK4/6 inhibitors. Given that BRD4 regulates CBX3 expression and PLK1 affects the binding between RB1 and CBX3, it is proposed that a dual BRD4/PLK1 inhibitor can increase the sensitivity of CRPC cells to CDK4/6 inhibitors partially through CBX3.
| S-EPMC10754129 | biostudies-literature
Project description:BACKGROUND:Prostate cancer responds poorly to current immunotherapies. Epigenetic therapies such as BET Bromodomain inhibition can change the transcriptome of tumor cells, possibly making them more immunogenic and thus susceptible to immune targeting. METHODS:We characterized the effects of BET bromodomain inhibition using JQ1 on PD-L1 and HLA-ABC expression in two human prostate cell lines, DU145 and PC3. RNA-Seq was performed to assess changes on a genome-wide level. A cytotoxic T cell killing assay was performed in MC38-OVA cells treated with JQ1 to demonstrate increased immunogenicity. In vivo experiments in the Myc-Cap model were conducted to show the effects of JQ1 administration in concert with anti-CTLA-4 checkpoint blockade. RESULTS:Here, we show that targeting BET bromodomains using the small molecule inhibitor JQ1 decreased PD-L1 expression and mitigated tumor progression in prostate cancer models. Mechanistically, BET bromodomain inhibition increased MHC I expression and increased the immunogenicity of tumor cells. Transcriptional profiling showed that BET bromodomain inhibition regulates distinct networks of antigen processing and immune checkpoint molecules. In murine models, treatment with JQ1 was additive with anti-CTLA-4 immunotherapy, resulting in an increased CD8/Treg ratio. CONCLUSIONS:BET Bromodomain inhibition can mediate changes in expression at a genome wide level in prostate cancer cells, resulting in an increased susceptibility to CD8 T cell targeting. These data suggest that combining BET bromodomain inhibition with immune checkpoint blockade may have clinical activity in prostate cancer patients.
| S-EPMC6814994 | biostudies-literature
Project description:BackgroundSingle-agent pembrolizumab treatment of hormone receptor-positive metastatic breast cancer (MBC) has demonstrated modest clinical responses. Little is known about potential biomarkers or mechanisms of response to immune checkpoint inhibitors (ICIs) in patients with HR+ MBC. The present study presents novel immune correlates of clinical responses to combined treatment with CDK4/6i and ICI.MethodsA combined analysis of two independent phase I clinical trials treating patients with HR+ MBC was performed. Patients treated with the combination of the CDK4/6i palbociclib+the ICI pembrolizumab+the aromatase inhibitor (AI) letrozole (palbo+pembro+AI) were compared with patients treated with pembrolizumab+AI (pembro+AI). Peripheral blood mononuclear cells collected at pretreatment, 3 weeks (cycle 2 day 1) and 9 weeks (cycle 4 day 1) were characterized by high-parameter flow cytometry to assess baseline immune subset composition and longitudinal changes in response to therapy.ResultsIn the peripheral blood, higher pretreatment frequencies of effector memory CD45RA+ CD8+ T cells and effector memory CD4+ T cells were observed in responders to palbo+pembro+AI. In contrast, this was not observed in pembro+AI-treated patients. We further characterized T-cell subsets of effector-like killer cell lectin-like receptor subfamily G member 1 (KLRG1+) ICOS+ CD4+ T cells and KLRG1+ CD45RA+ CD8+ T cells as baseline biomarkers of response. In comparison, pretreatment levels of tumor-infiltrating lymphocyte, tumor mutation burden, tumor programmed death-ligand 1 expression, and overall immune composition did not associate with clinical responses. Over the course of treatment, significant shifts in myeloid cell composition and phenotype were observed in palbo+pembro+AI-treated patients, but not in those treated with pembro+AI. We identified increased fractions of type 1 conventional dendritic cells (cDC1s) within circulating dendritic cells and decreased classical monocytes (cMO) within circulating monocytes only in patients treated with palbociclib. We also demonstrated that in palbociclib-treated patients, cDC1 and cMO displayed increased CD83 and human leukocyte antigen-DR isotype (HLA-DR) expression, respectively, suggesting increased maturation and antigen presentation capacity.ConclusionsPre-existing circulating effector CD8+ and CD4+ T cells and dynamic modulation of circulating myeloid cell composition denote response to combined pembrolizumab and palbociclib therapy for patients with HR+ MBC.Trial registration numberNCT02778685 and NCI02648477.
| S-EPMC7993344 | biostudies-literature
Project description:Adult T-cell leukemia/lymphoma (ATL) is an aggressive T-cell lymphoproliferative malignancy caused by human T-cell leukemia virus type 1 (HTLV-1). ATL is an orphan disease with no curative drug treatment regimens urgently needing new combination therapy. HTLV-1-infected cells rely on viral proteins, Tax and HBZ (HTLV-1-b-ZIP factor), to activate the transcription of various host genes that are critical for promoting leukemic transformation. Inhibition of bromodomain and extraterminal motif (BET) protein was previously shown to collapse the transcriptional network directed by BATF3 super-enhancer and thereby induced ATL cell apoptosis. In the current work, by using xenograft, ex vivo, and in vitro models, we demonstrated that I-BET762 (BETi) synergized with copanlisib (PI3Ki) and bardoxolone methyl (NF-κBi) to dramatically decrease the growth of ATL cells. Mechanistically, the triple combination exhibited synergistic activity by down-regulating the expression of c-MYC while upregulating the level of the glucocorticoid-induced leucine zipper (GILZ). The triple combination also enhanced apoptosis induction by elevating the expression of active caspase-3 and cleaved PARP. Importantly, the triple combination prolonged the survival of ATL-bearing xenograft mice and inhibited the proliferation of ATL cells from peripheral blood mononuclear cells (PBMCs) of both acute and smoldering/chronic ATL patients. Therefore, our data provide the rationale for a clinical trial exploring the multiagent combination of BET, PI3K/AKT, and NF-κB inhibitors for ATL patients and expands the potential treatments for this recalcitrant malignancy.
| S-EPMC9006306 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2020-04-08 | GSE131986 | GEO