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1.
Proc Natl Acad Sci U S A ; 121(7): e2307150121, 2024 Feb 13.
Article in English | MEDLINE | ID: mdl-38315842

ABSTRACT

Cyclin-dependent kinase 9 (CDK9) plays a critical role in transcription initiation and is essential for maintaining gene silencing at heterochromatic loci. Inhibition of CDK9 increases sensitivity to immunotherapy, but the underlying mechanism remains unclear. We now report that RNF20 stabilizes LSD1 via K29-mediated ubiquitination, which is dependent on CDK9-mediated phosphorylation. This CDK9- and RNF20-dependent LSD1 stabilization is necessary for the demethylation of histone H3K4, then subsequent repression of endogenous retrovirus, and an interferon response, leading to epigenetic immunosuppression. Moreover, we found that loss of RNF20 sensitizes cancer cells to the immune checkpoint inhibitor anti-PD-1 in vivo and that this effect can be rescued by the expression of ectopic LSD1. Our findings are supported by the observation that RNF20 levels correlate with LSD1 levels in human breast cancer specimens. This study sheds light on the role of RNF20 in CDK9-dependent LSD1 stabilization, which is crucial for epigenetic silencing and immunosuppression. Our findings explore the potential importance of targeting the CDK9-RNF20-LSD1 axis in the development of new cancer therapies.


Subject(s)
Cyclin-Dependent Kinase 9 , Histone Demethylases , Immune Tolerance , Ubiquitin-Protein Ligases , Humans , Cyclin-Dependent Kinase 9/genetics , Cyclin-Dependent Kinase 9/metabolism , Epigenesis, Genetic , Histone Demethylases/metabolism , Histones/metabolism , Ubiquitin-Protein Ligases/genetics
3.
Mol Med Rep ; 28(5)2023 11.
Article in English | MEDLINE | ID: mdl-37711045

ABSTRACT

Hypoxia can lead to programmed osteoblast death. Prevention of osteoblast apoptosis caused by hypoxia is of great significance in the study of the occurrence and development of bone necrosis. The present study aimed to investigate the effects and mechanism of fibroblast growth factor 23 (FGF23) on hypoxia­induced apoptosis in primary osteoblasts and MC3T3­E1 cells osteoblasts. Cells were transfected with a plasmid carrying the FGF23 gene and a cell model of hypoxia­induced apoptosis was established. FGF23 mRNA levels were measured using reverse transcription­quantitative (RT­q) PCR and western blotting was used to assess protein levels. Apoptosis was analyzed by MTT assay, fluorescein diacetate and ethidium bromide staining, flow cytometry and RT­qPCR and western blotting were used to verify the mRNA and protein levels of apoptosis­ and autophagy­related gene mRNA. The targeted relationship between miR­17­5p and FGF23 was confirmed using the StarBase database, TargetScan database and a luciferase reporter assay. FGF23 decreased cell survival and increased the rate of apoptosis. The mRNA and protein expression of the pro­apoptotic genes Bax and caspases 3 and 9 increased, whereas that of the anti­apoptotic Bcl­2 decreased. The expressions of the autophagy­associated proteins beclin­1, light chain 3­II (LC3­II) and the LC3­II/LC3­I ratio were significantly increased. In addition, a luciferase reporter assay confirmed that FGF23 directly regulated micro RNA (miR)­17­5p. The effects of FGF23 silencing were reversed by miR­17­5p inhibition. FGF23 may regulate hypoxia­induced osteoblast apoptosis by targeting miR­17­5p through the autophagy­signaling pathway. This provides a rationale for FGF23 as a potential therapeutic target for osteonecrosis of the femoral head.


Subject(s)
Fibroblast Growth Factor-23 , MicroRNAs , Apoptosis/genetics , Autophagy/genetics , MicroRNAs/genetics , Signal Transduction
4.
Mol Cancer Res ; 21(12): 1303-1316, 2023 12 01.
Article in English | MEDLINE | ID: mdl-37540490

ABSTRACT

Lysine-specific demethylase 1 (LSD1), a critical chromatin modulator, functions as an oncogene by demethylation of H3K4me1/2. The stability of LSD1 is governed by a complex and intricate process involving ubiquitination and deubiquitination. Several deubiquitinases preserve LSD1 protein levels. However, the precise mechanism underlying the degradation of LSD1, which could mitigate its oncogenic function, remains unknown. To gain a better understanding of LSD1 degradation, we conducted an unbiased siRNA screening targeting all the human SCF family E3 ligases. Our screening identified FBXO24 as a genuine E3 ligase that ubiquitinates and degrades LSD1. As a result, FBXO24 inhibits LSD1-induced tumorigenesis and functions as a tumor suppressor in breast cancer cells. Moreover, FBXO24 exhibits an inverse correlation with LSD1 and is associated with a favorable prognosis in breast cancer patient samples. Taken together, our study uncovers the significant role of FBXO24 in impeding breast tumor progression by targeting LSD1 for degradation. IMPLICATIONS: Our study provides comprehensive characterization of the significant role of FBXO24 in impeding breast tumor progression by targeting LSD1 for degradation.


Subject(s)
Breast Neoplasms , Female , Humans , Breast Neoplasms/pathology , Carcinogenesis/genetics , Cell Line, Tumor , Cell Transformation, Neoplastic , Histone Demethylases/metabolism , Ubiquitin-Protein Ligases/genetics , Ubiquitination
5.
Mol Ther Oncolytics ; 28: 293-306, 2023 Mar 16.
Article in English | MEDLINE | ID: mdl-36911068

ABSTRACT

Epithelial ovarian cancer (EOC) remains one of the leading causes of cancer-related deaths among women worldwide. Receptor tyrosine kinases (RTKs) have long been sought as therapeutic targets for EOC, as they are frequently hyperactivated in primary tumors and drive disease relapse, progression, and metastasis. More recently, these oncogenic drivers have been implicated in EOC response to poly(ADP-ribose) polymerase (PARP) inhibitors and epigenome-interfering agents. This evidence revives RTKs as promising targets for therapeutic intervention of EOC. This review summarizes recent studies on the role of RTKs in EOC malignancy and the use of their inhibitors for clinical treatment. Our focus is on the ERBB family, c-Met, and VEGFR, as they are linked to drug resistance and targetable using commercially available drugs. The importance of these RTKs and their inhibitors is highlighted by their impact on signal transduction and intratumoral heterogeneity in EOC and successful use as maintenance therapy in the clinic through suppression of the VEGF/VEGFR axis. Finally, the therapeutic potential of RTK inhibitors is discussed in the context of combinatorial targeting via co-inhibiting proliferative and anti-apoptotic pathways, epigenomic/transcriptional programs, and harnessing the efficacy of PARP inhibitors and programmed cell death 1/ligand 1 immune checkpoint therapies.

7.
JCI Insight ; 8(1)2023 01 10.
Article in English | MEDLINE | ID: mdl-36413416

ABSTRACT

Chronic inflammation is associated with lung tumorigenesis, in which NF-κB-mediated epigenetic regulation plays a critical role. Lung tumor suppressor G protein-coupled receptor, family C, member 5A (GPRC5A), is repressed in most non-small cell lung cancer (NSCLC); however, the mechanisms remain unclear. Here, we show that NF-κB acts as a transcriptional repressor in suppression of GPRC5A. NF-κB induced GPRC5A repression both in vitro and in vivo. Intriguingly, transactivation of NF-κB downstream targets was not required, but the transactivation domain of RelA/p65 was required for GPRC5A repression. NF-κB did not bind to any potential cis-element in the GPRC5A promoter. Instead, p65 was complexed with retinoic acid receptor α/ß (RARα/ß) and recruited to the RA response element site at the GPRC5A promoter, resulting in disrupted RNA polymerase II complexing and suppressed transcription. Notably, phosphorylation on serine 276 of p65 was required for interaction with RARα/ß and repression of GPRC5A. Moreover, NF-κB-mediated epigenetic repression was through suppression of acetylated histone H3K9 (H3K9ac), but not DNA methylation of the CpG islands, at the GPRC5A promoter. Consistently, a histone deacetylase inhibitor, but not DNA methylation inhibitor, restored GPRC5A expression in NSCLC cells. Thus, NF-κB induces transcriptional repression of GPRC5A via a complex with RARα/ß and mediates epigenetic repression via suppression of H3K9ac.


Subject(s)
Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , Humans , NF-kappa B/metabolism , Carcinoma, Non-Small-Cell Lung/genetics , Transcriptional Activation , Epigenesis, Genetic , Lung Neoplasms/genetics , Lung Neoplasms/metabolism , Lung/metabolism , Receptors, G-Protein-Coupled/genetics , Receptors, G-Protein-Coupled/metabolism , Receptors, Retinoic Acid/genetics , Receptors, Retinoic Acid/metabolism , Epithelial Cells/metabolism
8.
Oxid Med Cell Longev ; 2022: 6360133, 2022.
Article in English | MEDLINE | ID: mdl-36275897

ABSTRACT

Objective: Glucocorticoid-induced osteonecrosis of the femoral head is one of the most common causes of nontraumatic osteonecrosis of the femoral head, but its exact pathogenesis remains unclear. The aim of this study was to investigate the role of SIRT6 in the maintenance of bone tissue morphology and structure, intravascular lipid metabolism, and its potential molecular mechanism in glucocorticoid-induced osteonecrosis of the femoral head. Methods: SIRT6 adenovirus was transfected into GIONFH in rats. The microstructure of rat bone was observed by micro-CT and histological staining, and the expression of bone formation-related proteins and angiogenesis-related factors was determined through western blot and immunohistochemistry. Alkaline phosphatase activity, alizarin red staining, and the expression levels of Runx2 and osteocalcin were used to evaluate the osteogenic potential. And in vitro tube formation assay and immunofluorescence were used to detect the ability of endothelial cell angiogenesis. Results: Dexamethasone significantly inhibited osteoblast differentiation, affected bone formation, and destroyed microvessel formation, increased the intracellular Fe2+ and ROS levels and induced the occurrence of ferroptosis. SIRT6 can inhibit ferroptosis and restore the ability of bone formation and angiogenesis. Conclusion: SIRT6 can inhibit the occurrence of ferroptosis, reduce the damage of vascular endothelium, and promote osteogenic differentiation, so as to prevent the occurrence of osteonecrosis of the femoral head.


Subject(s)
Osteonecrosis , Sirtuins , Animals , Rats , Alkaline Phosphatase/metabolism , Core Binding Factor Alpha 1 Subunit/metabolism , Dexamethasone , Femur Head/metabolism , Glucocorticoids/pharmacology , Osteocalcin/metabolism , Osteogenesis , Osteonecrosis/chemically induced , Osteonecrosis/metabolism , Reactive Oxygen Species/metabolism , Sirtuins/metabolism
9.
Proc Natl Acad Sci U S A ; 119(28): e2119518119, 2022 07 12.
Article in English | MEDLINE | ID: mdl-35867755

ABSTRACT

Early B cell factor 1 (EBF1) is a transcriptional factor with a variety of roles in cell differentiation and metabolism. However, the functional roles of EBF1 in tumorigenesis remain elusive. Here, we demonstrate that EBF1 is highly expressed in triple-negative breast cancer (TNBC). Furthermore, EBF1 has a pivotal role in the tumorigenicity and progression of TNBC. Moreover, we found that depletion of EBF1 induces extensive cell mitophagy and inhibits tumor growth. Genome-wide mapping of the EBF1 transcriptional regulatory network revealed that EBF1 drives TNBC tumorigenicity by assembling a transcriptional complex with HIF1α that fine-tunes the expression of HIF1α targets via suppression of p300 activity. EBF1 therefore holds HIF1α activity in check to avert extensive mitophagy-induced cell death. Our findings reveal a key function for EBF1 as a master regulator of mitochondria homeostasis in TNBC and indicate that targeting this pathway may offer alternative treatment strategies for this aggressive subtype of breast cancer.


Subject(s)
Hypoxia-Inducible Factor 1, alpha Subunit , Trans-Activators , Triple Negative Breast Neoplasms , Carcinogenesis/genetics , Cell Line, Tumor , Cell Proliferation , Gene Expression Regulation, Neoplastic , Humans , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Signal Transduction , Trans-Activators/genetics , Trans-Activators/metabolism , Triple Negative Breast Neoplasms/metabolism , Triple Negative Breast Neoplasms/pathology
10.
J Healthc Eng ; 2022: 9364467, 2022.
Article in English | MEDLINE | ID: mdl-35190765

ABSTRACT

BACKGROUND: Osteonecrosis of the femoral head (ONFH) is a common hip joint disease, which is more harmful and seriously affects the lives of patients. This study aims to clarify the regulatory mechanism of lncRNA FGD5-AS1 in ONFH. METHODS: The expression of the protein and mRNA was detected by RT-qPCR and Western blot assay. The regulatory mechanism of lncRNA FGD5-AS1 was detected by the dual-luciferase reporter assay, CCK-8 assay, and flow cytometry assay. RESULTS: Dex can inhibit cell proliferation and differentiation and induce apoptosis in hBMSCs in a dose-dependent manner. Overexpression of lncRNA FGD5-AS1 promoted cell proliferation and restrained apoptosis in Dex-treated hBMSCs. In addition, lncRNA FGD5-AS1 acts as a sponge for miR-296-5p. Also, miR-296-5p directly targets STAT3. More importantly, miR-296-5p and STAT3 can affect the function of lncRNA FGD5-AS1 in Dex-treated hBMSCs. CONCLUSION: lncRNA FGD5-AS1 promotes cell proliferation and inhibits apoptosis in steroid-induced ONFH through acting as a sponge for miR-296-5p and upregulation of STAT3.


Subject(s)
MicroRNAs , Osteonecrosis , RNA, Long Noncoding , Apoptosis/genetics , Bone Marrow/metabolism , Cell Proliferation , Femur Head/metabolism , Guanine Nucleotide Exchange Factors/genetics , Guanine Nucleotide Exchange Factors/metabolism , Humans , MicroRNAs/genetics , MicroRNAs/metabolism , Osteonecrosis/chemically induced , Osteonecrosis/genetics , RNA, Long Noncoding/genetics , STAT3 Transcription Factor/genetics , STAT3 Transcription Factor/metabolism , Steroids
11.
Cancer Res ; 82(6): 1025-1037, 2022 03 15.
Article in English | MEDLINE | ID: mdl-35045987

ABSTRACT

While initiation is established as a critical step in tumorigenesis, the identity of the cell of origin for lung adenocarcinoma and the mechanism controlling susceptibility to initiation remain elusive. Here we show that lung tumor suppressor Gprc5a-knockout (KO) mice are susceptible to initiation of lung tumorigenesis. Bronchioalveolar stem cells (BASC) and alveolar type 2 (AT2) cells were aberrantly expanded in Gprc5a-KO mouse lungs compared with those in wild-type (WT) mice, suggesting that Gprc5a-KO might confer susceptibility to initiation by increasing the cell of origin in mouse lungs. BASCs from Gprc5a-KO mice (KO-BASC) exhibited significantly increased stemness and self-renewal potential and reduced differentiation capacity compared with BASCs from WT mice (WT-BASC). AT2 cells did not possess self-renewal potential regardless of Gprc5a status. KO-BASCs expressed a stem-like gene profile with upregulated Abcg2, EGFR, and NF-κB signaling compared with WT-BASCs. Blockade of EGFR and NF-κB signaling inhibited both expansion of BASC and AT2 cells and lung tumorigenesis. Abcg2 was expressed in active KO-BASCs as well as in lung tumor cells but not in quiescent WT-BASCs or AT2 cells, supporting that lung adenocarcinoma cells are derived from Abcg2-positive KO-BASCs (active). Taken together, Gprc5a deletion leads to expansion of active BASCs via dysregulated EGFR and NF-κB signaling that confers susceptibility to initiation of lung tumorigenesis, marking Abcg2-positive BASCs as candidate cell of origin for lung adenocarcinoma. SIGNIFICANCE: Identification of active bronchioalveolar stem cells as lung adenocarcinoma cells of origin provides insights into mechanisms of lung tumorigenesis and could facilitate development of effective strategies for cancer prevention and therapy. See related commentary by Osborne and Minna, p. 972.


Subject(s)
Adenocarcinoma of Lung , Lung Neoplasms , Stem Cells , Adenocarcinoma of Lung/genetics , Adenocarcinoma of Lung/metabolism , Animals , Carcinogenesis , Cell Transformation, Neoplastic , ErbB Receptors/genetics , ErbB Receptors/metabolism , Humans , Lung/metabolism , Lung Neoplasms/genetics , Lung Neoplasms/metabolism , Mice , Mice, Knockout , NF-kappa B/metabolism , Receptors, G-Protein-Coupled/genetics , Receptors, G-Protein-Coupled/metabolism
12.
Int J Mol Sci ; 22(20)2021 Oct 14.
Article in English | MEDLINE | ID: mdl-34681726

ABSTRACT

SNAI1, a zinc finger transcription factor, not only acts as the master regulator of epithelial-mesenchymal transition (EMT) but also functions as a driver of cancer progression, including cell invasion, survival, immune regulation, stem cell properties, and metabolic regulation. The regulation of SNAI1 occurs at the transcriptional, translational, and predominant post-translational levels including phosphorylation, acetylation, and ubiquitination. Here, we discuss the regulation and role of SNAI1 in cancer metastasis, with a particular emphasis on epigenetic regulation and post-translational modifications. Understanding how signaling networks integrate with SNAI1 in cancer progression will shed new light on the mechanism of tumor metastasis and help develop novel therapeutic strategies against cancer metastasis.


Subject(s)
Neoplasms/pathology , Snail Family Transcription Factors/metabolism , Epigenesis, Genetic , Epithelial-Mesenchymal Transition , Histones/metabolism , Humans , Neoplasm Metastasis , Neoplasms/metabolism , Protein Processing, Post-Translational , Snail Family Transcription Factors/chemistry , Snail Family Transcription Factors/genetics
13.
Theranostics ; 11(16): 7658-7670, 2021.
Article in English | MEDLINE | ID: mdl-34335956

ABSTRACT

SNAI1 is widely regarded as a master driver of epithelial-mesenchymal transition (EMT) and associated with breast cancer progression and metastasis. This pro-malignant role is strongly linked to posttranslational modification, especially phosphorylation, which controls its protein levels and subcellular localization. While multiple kinases are implicated in regulation of SNAI1 stability, the precise mechanism by which SNAI1 is stabilized in tumors remains to be fully elucidated. Methods: A series of in vitro and in vivo experiments were conducted to reveal the regulation of SNAI1 by Serine/Threonine Kinase 39 (STK39) and the role of STK39 in breast cancer metastasis. Results: We identified STK39, a member of Stem 20-like serine/threonine kinase family, as a novel posttranslational regulator that enhances the stability of SNAI1. Inhibition of STK39 via knockdown or use of a specific inhibitor resulted in SNAI1 destabilization. Mechanistically, STK39 interacted with and phosphorylated SNAI1 at T203, which is critical for its nuclear retention. Functionally, STK39 inhibition markedly impaired the EMT phenotype and decreased tumor cell migration, invasion, and metastasis both in vitro and in vivo. These effects were rescued by ectopic SNAI1 expression. In addition, depletion of STK39 dramatically enhanced sensitivity to chemotherapeutic agents. Conclusions: Our study demonstrated that STK39 is a key mediator of SNAI1 stability and is associated with the pro-metastatic cellular process, highlighting the STK39-SNAI1 signaling axis as promising therapeutic targets for treatments of metastatic breast cancer.


Subject(s)
Breast Neoplasms/metabolism , Protein Serine-Threonine Kinases/metabolism , Snail Family Transcription Factors/metabolism , Animals , Breast Neoplasms/physiopathology , Cell Line, Tumor , Cell Movement/genetics , Epithelial-Mesenchymal Transition/genetics , Female , Gene Expression Regulation, Neoplastic/genetics , Humans , Mice , Mice, SCID , Neoplasm Invasiveness/genetics , Phosphorylation , Protein Serine-Threonine Kinases/genetics , Snail Family Transcription Factors/genetics , Transcription Factors/metabolism
14.
J Mater Sci Mater Med ; 32(4): 36, 2021 Mar 29.
Article in English | MEDLINE | ID: mdl-33779853

ABSTRACT

To evaluate the performance of a composite scaffold of Wharton's jelly (WJ) and chondroitin sulfate (CS) and the effect of the composite scaffold loaded with human umbilical cord mesenchymal stem cells (hUCMSCs) in repairing articular cartilage defects, two experiments were carried out. The in vitro experiments involved identification of the hUCMSCs, construction of the biomimetic composite scaffolds by the physical and chemical crosslinking of WJ and CS, and testing of the biomechanical properties of both the composite scaffold and the WJ scaffold. In the in vivo experiments, composite scaffolds loaded with hUCMSCs and WJ scaffolds loaded with hUCMSCs were applied to repair articular cartilage defects in the rat knee. Moreover, their repair effects were evaluated by the unaided eye, histological observations, and the immunogenicity of scaffolds and hUCMSCs. We found that in vitro, the Young's modulus of the composite scaffold (WJ-CS) was higher than that of the WJ scaffold. In vivo, the composite scaffold loaded with hUCMSCs repaired rat cartilage defects better than did the WJ scaffold loaded with hUCMSCs. Both the scaffold and hUCMSCs showed low immunogenicity. These results demonstrate that the in vitro construction of a human-derived WJ-CS composite scaffold enhances the biomechanical properties of WJ and that the repair of knee cartilage defects in rats is better with the composite scaffold than with the single WJ scaffold if the scaffold is loaded with hUCMSCs.


Subject(s)
Cartilage, Articular/metabolism , Chondroitin Sulfates/chemistry , Hindlimb/physiology , Mesenchymal Stem Cells/cytology , Tissue Scaffolds/chemistry , Umbilical Cord/metabolism , Wharton Jelly/chemistry , Animals , Biomechanical Phenomena , Cartilage , Cell Differentiation , Chondrocytes/cytology , Immunohistochemistry , In Vitro Techniques , Interleukin-6/metabolism , Male , Rats , Rats, Sprague-Dawley , Tissue Engineering
16.
Biomed Res Int ; 2021: 9977001, 2021.
Article in English | MEDLINE | ID: mdl-35005025

ABSTRACT

PURPOSE: A number of studies have discovered various roles of PAK4 in human tumors, including osteosarcoma. However, the exact role of PAK4 in osteosarcoma and its mechanism have yet to be determined. Therefore, this study focused on interrogating the PAK4 effect on the proliferation and migration ability of osteosarcoma and its underlying mechanisms. MATERIALS AND METHODS: Western blot and QRT-PCR were utilized to quantify the PAK4 relative protein and mRNA levels. To measure cellular viability and mobility, the MTT and wound-healing assays were preferred. RESULTS: With the adenovirus-mediated overexpression of PAK4, the proliferation and migration of U2-OS and MG-63 osteosarcoma cells were stimulated. Furthermore, a liposome-mediated knockout of PAK4 will inhibit osteosarcoma cells from proliferating. In terms of mechanism, we observed the positive correlation of PAK4 expression with expression of P21, CyclinD1, CyclinE1, CDK2, and CDK6, which drives G0/G1 to the G2/M phase transition. PAK4 can also activate Erk expression in OS cells and induce EMT. CONCLUSION: Interfering with PAK4 protein expression has been shown to affect osteosarcoma proliferation and migration.


Subject(s)
Bone Neoplasms/metabolism , Cell Movement/physiology , Cell Proliferation/physiology , Osteosarcoma/metabolism , p21-Activated Kinases/metabolism , Bone Neoplasms/pathology , Cell Cycle/physiology , Cell Line, Tumor , Cell Survival/physiology , Gene Expression Regulation, Neoplastic/physiology , Humans , Osteosarcoma/pathology
17.
Cancer Res ; 81(3): 552-566, 2021 02 01.
Article in English | MEDLINE | ID: mdl-33229341

ABSTRACT

Cancer cells need to generate large amounts of glutathione (GSH) to buffer oxidative stress during tumor development. A rate-limiting step for GSH biosynthesis is cystine uptake via a cystine/glutamate antiporter Xc-. Xc- is a sodium-independent antiporter passively driven by concentration gradients from extracellular cystine and intracellular glutamate across the cell membrane. Increased uptake of cystine via Xc- in cancer cells increases the level of extracellular glutamate, which would subsequently restrain cystine uptake via Xc-. Cancer cells must therefore evolve a mechanism to overcome this negative feedback regulation. In this study, we report that glutamate transporters, in particular SLC1A1, are tightly intertwined with cystine uptake and GSH biosynthesis in lung cancer cells. Dysregulated SLC1A1, a sodium-dependent glutamate carrier, actively recycled extracellular glutamate into cells, which enhanced the efficiency of cystine uptake via Xc- and GSH biosynthesis as measured by stable isotope-assisted metabolomics. Conversely, depletion of glutamate transporter SLC1A1 increased extracellular glutamate, which inhibited cystine uptake, blocked GSH synthesis, and induced oxidative stress-mediated cell death or growth inhibition. Moreover, glutamate transporters were frequently upregulated in tissue samples of patients with non-small cell lung cancer. Taken together, active uptake of glutamate via SLC1A1 propels cystine uptake via Xc- for GSH biosynthesis in lung tumorigenesis. SIGNIFICANCE: Cellular GSH in cancer cells is not only determined by upregulated Xc- but also by dysregulated glutamate transporters, which provide additional targets for therapeutic intervention.


Subject(s)
Cystine/metabolism , Excitatory Amino Acid Transporter 3/metabolism , Glutamic Acid/metabolism , Glutathione/biosynthesis , Lung Neoplasms/metabolism , Animals , Antiporters/metabolism , Cell Death , Cell Line, Tumor , Glutamine/deficiency , Lung Neoplasms/etiology , Lung Neoplasms/pathology , Mice , Mice, Nude , Oxidative Stress , Receptors, G-Protein-Coupled , Stress, Physiological , Up-Regulation
18.
Front Pharmacol ; 11: 596239, 2020.
Article in English | MEDLINE | ID: mdl-33343366

ABSTRACT

Epithelial-mesenchymal Transition (EMT) is a de-differentiation process in which epithelial cells lose their epithelial properties to acquire mesenchymal features. EMT is essential for embryogenesis and wound healing but is aberrantly activated in pathological conditions like fibrosis and cancer. Tumor-associated EMT contributes to cancer cell initiation, invasion, metastasis, drug resistance and recurrence. This dynamic and reversible event is governed by EMT-transcription factors (EMT-TFs) with epigenetic complexes. In this review, we discuss recent advances regarding the mechanisms that modulate EMT in the context of epigenetic regulation, with emphasis on epigenetic drugs, such as DNA demethylating reagents, inhibitors of histone modifiers and non-coding RNA medication. Therapeutic contributions that improve epigenetic regulation of EMT will translate the clinical manifestation as treating cancer progression more efficiently.

19.
Cell Oncol (Dordr) ; 43(6): 1049-1066, 2020 Dec.
Article in English | MEDLINE | ID: mdl-33006750

ABSTRACT

PURPOSE: Stemming from a myriad of genetic and epigenetic alterations, triple-negative breast cancer (TNBC) is tied to poor clinical outcomes and aspires for individualized therapies. Here we investigated the therapeutic potential of co-inhibiting integrin-dependent signaling pathway and BRD4, a transcriptional and epigenetic mediator, for TNBC. METHODS: Two independent patient cohorts were subjected to bioinformatic and IHC examination for clinical association of candidate cancer drivers. The efficacy and biological bases for co-targeting these drivers were interrogated using cancer cell lines, a protein kinase array, chemical inhibitors, RNAi/CRISPR/Cas9 approaches, and a 4 T1-Balb/c xenograft model. RESULTS: We found that amplification of the chromosome 8q24 region occurred in nearly 20% of TNBC tumors, and that it coincided with co-upregulation or amplification of c-Myc and FAK, a key effector of integrin-dependent signaling. This co-upregulation at the mRNA or protein level correlated with a poor patient survival (p < 0.0109 or p < 0.0402, respectively). Furthermore, we found that 14 TNBC cell lines exhibited high vulnerabilities to the combination of JQ1 and VS-6063, potent pharmacological antagonists of the BRD4/c-Myc and integrin/FAK-dependent pathways, respectively. We also observed a cooperative inhibitory effect of JQ1 and VS-6063 on tumor growth and infiltration of Ly6G+ myeloid-derived suppressor cells in vivo. Finally, we found that JQ1 and VS-6063 cooperatively induced apoptotic cell death by altering XIAP, Bcl2/Bcl-xl and Bim levels, impairing c-Src/p130Cas-, PI3K/Akt- and RelA-associated signaling, and were linked to EMT-inducing transcription factor Snail- and Slug-dependent regulation. CONCLUSION: Based on our results, we conclude that the BRD4/c-Myc- and integrin/FAK-dependent pathways act in concert to promote breast cancer cell survival and poor clinical outcomes. As such, they represent promising targets for a synthetic lethal-type of therapy against TNBC.


Subject(s)
Cell Cycle Proteins/metabolism , Integrins/metabolism , Signal Transduction , Transcription Factors/metabolism , Triple Negative Breast Neoplasms/metabolism , Azepines/pharmacology , Bcl-2-Like Protein 11/metabolism , Benzamides/pharmacology , Cell Death/drug effects , Cell Line, Tumor , Cell Survival/drug effects , Focal Adhesion Protein-Tyrosine Kinases/genetics , Focal Adhesion Protein-Tyrosine Kinases/metabolism , Gene Expression Regulation, Neoplastic , Genome, Human , Humans , Proto-Oncogene Proteins c-myc/genetics , Proto-Oncogene Proteins c-myc/metabolism , Pyrazines/pharmacology , RNA, Messenger/genetics , RNA, Messenger/metabolism , Signal Transduction/drug effects , Sulfonamides/pharmacology , Triazoles/pharmacology , Triple Negative Breast Neoplasms/genetics , Triple Negative Breast Neoplasms/pathology
20.
Front Cell Dev Biol ; 8: 652, 2020.
Article in English | MEDLINE | ID: mdl-32793596

ABSTRACT

We investigated the therapeutic potential of targeting integrin/FAK-dependent signaling, an adhesion receptor-mediated pathway that has been increasingly linked to non-small cell lung cancer (NSCLC) malignancy. Our analysis of the TCGA cohort showed that a subset of pro-tumorigenic integrins, including α1ß1, α2ß1, α3ß1, α5ß1, and α6ß4, were frequently amplified or upregulated at the genomic or mRNA level in KRAS or EGFR mutation/overexpression-enriched adenocarcinomas. These alterations appeared complementary, correlated with poor patient survival (p < 0.0072), and were collaborative with KRAS mutation-coupled αv integrins (p < 0.00159). Since integrin/FAK-dependent signaling is tightly coupled with normal human physiology, we sought to use a synthetic lethal-type targeting comprising of VS-6063, a chemical inhibitor of integrin-mediated FAK activity, and A549 cells, which carry a KRAS mutation and EGFR overexpression. Our screening analysis revealed that JQ1 and IBET-762, inhibitors of epigenetic reader BRD4, and LBH589, a pan inhibitor of histone deacetylases (HDACs), exhibited synergy with VS-6063 in mitigating tumor cell viability. This epigenetic link was corroborated by strong effects of additional inhibitors and RNAi-mediated knockdown of FAK and BRD4 or its downstream effector, c-Myc. Low doses of JQ1 (≤0.5 µM) markedly escalated efficacy of VS-6063 across a panel of 10 NSCLC cell lines. This catalyst-like effect is in line with the oncogenic landscape in the TCGA cohort since c-Myc falls downstream of the KRAS and EGFR oncogenes. Mechanistically, co-inhibiting the integrin-FAK and BRD4/c-Myc axes synergistically induced apoptotic cell death and DNA damage response, and impaired stemness-associated tumorsphere formation. These effects were accompanied by a marked inhibition of Akt- and p130Cas/Src-dependent signaling, but not Erk1/2 activity. Meanwhile, JQ1 alone or in combination with VS-6063 attenuated cell-cell adhesion and extracellular matrix (ECM)-dependent cell spreading, which is reminiscent of phenotype induced by malfunctional E-cadherin or integrins. Paradoxically, this phenotypic impact coincided with downregulation of epithelial-mesenchymal transition (EMT)-inducting transcription factor ZEB1 or Snail. Finally, we showed that the effect of the VS-6063/JQ1 combination was nearly equivalent to that of VS-6063 plus Carboplatin or Osimertinib. Overall, our study indicates that the integrin/FAK and BRD4/c-Myc axes cooperatively drive NSCLC virulence, and a co-targeting may provide a line of therapy capable of overcoming EGFR/KRAS-driven malignancy.

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