ABSTRACT
Noncoding RNAs with a length of 2224 nt are known as microRNAs (miRNAs or miRs), which are critical regulators of protein translation. Over the past 10 years, the roles of miRNAs have been extensively investigated in several human cancer types. There is evidence to indicate that miRNAs regulate gene expression by concentrating on a number of substances that have an impact on the physiology and development of cancer cells. Thus, miRNAs as regarded as effective targets for further studies on the design of novel therapeutic strategies. Hepatocellular carcinoma, breast, prostate, and ovarian cancer are only a few of the cancers that miR124 suppresses. Furthermore, it has been shown that miR124 is linked to the development and aggressive spread of malignancies. The aim of the present review was to clarify and highlight the role of miR124 in the development and progression of cancer, emphasizing recent research illustrating how miR124 has been used as a therapeutic agent against cancer, as well as the diagnostic potential, regulatory mechanisms and clinical application of miR124.
Subject(s)
Carcinoma, Hepatocellular , Liver Neoplasms , MicroRNAs , Ovarian Neoplasms , Male , Female , Humans , MicroRNAs/genetics , MicroRNAs/metabolismABSTRACT
Background: Focal adhesion serves as a bridge between tumour cells and the extracellular matrix (ECM) and has multiple roles in tumour invasion, migration, and therapeutic resistance. However, studies on focal adhesion-related genes (FARGs) in head and neck squamous cell carcinoma (HNSCC) are limited. Methods: Data on HNSCC samples were obtained from The Cancer Genome Atlas and GSE41613 datasets, and 199 FARGs were obtained from the Molecular Signatures database. The integrated datasets' dimensions were reduced by the use of cluster analysis, which was also used to classify patients with HNSCC into subclusters. A FARG signature model was developed and utilized to calculate each patient's risk score using least extreme shrinkage and selection operator regression analysis. The risk score was done to quantify the subgroups of all patients. We evaluated the model's value for prognostic prediction, immune infiltration status, and therapeutic response in HNSCC. Preliminary molecular and biological experiments were performed to verify these results. Results: Two different HNSCC molecular subtypes were identified according to FARGs, and patients with C2 had a shorter overall survival (OS) than those with C1. We constructed an FARG signature comprising nine genes. We constructed a FARG signature consisting of nine genes. Patients with higher risk scores calculated from the FARG signature had a lower OS, and the FARG signature was considered an independent prognostic factor for HNSCC in univariate and multivariate analyses. FARGs are associated with immune cell invasion, gene mutation status, and chemosensitivity. Finally, we observed an abnormal overexpression of MAPK9 in HNSCC tissues, and MAPK9 knockdown greatly impeded the proliferation, migration, and invasion of HNSCC cells. Conclusion: The FARG signature can provide reliable prognostic prediction for patients with HNSCC. Apart from that, the genes in this model were related to immune invasion, gene mutation status, and chemosensitivity, which may provide new ideas for targeted therapies for HNSCC.
Subject(s)
Focal Adhesions , Head and Neck Neoplasms , Humans , Cell Adhesion , Squamous Cell Carcinoma of Head and Neck/genetics , Prognosis , Head and Neck Neoplasms/geneticsABSTRACT
FOXG1 (forkhead box G1) syndrome is a neurodevelopmental disorder caused by variants in the Foxg1 gene that affect brain structure and function. Individuals affected by FOXG1 syndrome frequently exhibit delayed myelination in neuroimaging studies, which may impair the rapid conduction of nerve impulses. To date, the specific effects of FOXG1 on oligodendrocyte lineage progression and myelination during early postnatal development remain unclear. Here, we investigated the effects of Foxg1 deficiency on myelin development in the mouse brain by conditional deletion of Foxg1 in neural progenitors using NestinCreER;Foxg1fl/fl mice and tamoxifen induction at postnatal day 0 (P0). We found that Foxg1 deficiency resulted in a transient delay in myelination, evidenced by decreased myelin formation within the first two weeks after birth, but ultimately recovered to the control levels by P30. We also found that Foxg1 deletion prevented the timely attenuation of platelet-derived growth factor receptor alpha (PDGFRα) signaling and reduced the cell cycle exit of oligodendrocyte precursor cells (OPCs), leading to their excessive proliferation and delayed maturation. Additionally, Foxg1 deletion increased the expression of Hes5, a myelin formation inhibitor, as well as Olig2 and Sox10, two promoters of OPC differentiation. Our results reveal the important role of Foxg1 in myelin development and provide new clues for further exploring the pathological mechanisms of FOXG1 syndrome.
Subject(s)
Brain , Rett Syndrome , Animals , Mice , Action Potentials , Cell Cycle , Cell Differentiation/genetics , Nerve Tissue Proteins/genetics , Forkhead Transcription FactorsABSTRACT
BACKGROUND: Thyroid disease is a common endocrine disorder, and thyroid surgeries and postoperative complications have increased recently. This study aimed to explore the effectiveness of intraoperative nerve monitoring (IONM) in endoscopic thyroid surgery using subgroup analysis and determine confounding factors. MATERIALS AND METHODS: Two researchers individually searched for relevant studies published till November 2022 in the PubMed, Embase, Web of Science and Cochrane Library databases. Eventually, eight studies met the inclusion criteria. Heterogeneity was assessed using the Cochran's Q test, and a funnel plot was implemented to evaluate publication bias. The odds ratio or risk difference were calculated using fixed-effects models. The weighted mean difference of continuous variables was calculated. Subgroup analysis was performed according to the disease type. RESULTS: Eight eligible papers included 915 patients and 1242 exposed nerves. The frequencies of transient, permanent and total recurrent laryngeal nerve (RLN) palsy were 2.64, 0.19 and 2.83%, respectively, in the IONM group and 6.15, 0.75 and 6.90%, respectively, in the conventional exposure group. In addition, analysis of the secondary outcome indicators for the average total length of surgery, localisation time of the RLN, recognition rate of the superior laryngeal nerve and length of incision revealed that IONM reduced the localisation time of the RLN and increased the identification rate of the superior laryngeal nerve. Subgroup analysis showed that IONM significantly reduced the incidence of RLN palsy in patients with malignancies. CONCLUSIONS: The use of IONM significantly reduced the incidence of transient RLN palsy during endoscopic thyroid surgery, but it did not significantly reduce the incidence of permanent RLN palsy. However, the reduction in the total RLN palsy was statistically significant. In addition, IONM can effectively reduce the location time of the RLN and increase the recognition rate of the superior laryngeal nerve. Therefore, the application of IONM for malignant tumours is recommended.
Subject(s)
Recurrent Laryngeal Nerve Injuries , Vocal Cord Paralysis , Humans , Thyroid Gland/surgery , Thyroidectomy/adverse effects , Recurrent Laryngeal Nerve/physiology , Monitoring, Intraoperative , Recurrent Laryngeal Nerve Injuries/etiology , Recurrent Laryngeal Nerve Injuries/prevention & control , Vocal Cord Paralysis/etiology , Vocal Cord Paralysis/prevention & controlABSTRACT
Purpose: Head and neck squamous cell carcinoma (HNSCC) is a very diverse malignancy with a poor prognosis. The purpose of this study was to develop a new signature based on 12 ion channel genes to predict the outcome and immune status of HNSCC patients. Methods: Clinicopathological information and gene sequencing data of HNSCC patients were generated from the Cancer Genome Atlas and Gene Expression Omnibus databases. A set of 323 ion channel genes was obtained from the HUGO Gene Nomenclature Committee database and literature review. Using univariate Cox regression analysis, the ion channel genes related to HNSCC prognosis were identified. A prognostic signature and nomogram were then created using machine learning methods. Kaplan-Meier analysis was used to explore the relevance of the risk scores and overall survival (OS). We also investigated the association between risk scores, tumor immune infiltration, and gene mutational status. Finally, we detected the expression levels of the signature genes by quantitative real-time polymerase chain reaction, western blotting, and immunohistochemistry. Results: We separated the patients into high- and low-risk groups according to the risk scores computed based on these 12 ion channel genes, and the OS of the low-risk group was significantly longer (p<0.001). The area under the curve for predicting 3-year survival was 0.729. Univariate and multivariate analyses showed that the 12-ion-channel-gene risk model was an independent prognostic factor. We also developed a nomogram model based on risk scores and clinicopathological variables to forecast outcomes. Furthermore, immune cell infiltration, gene mutation status, immunotherapy response, and chemotherapeutic treatment sensitivity were all linked to risk scores. Moreover, high expression levels of ANO1, AQP9, and BEST2 were detected in HNSCC tissues, whereas AQP5, SCNN1G, and SCN4A expression was low in HNSCC tissues, as determined by experiments. Conclusion: The 12-ion-channel-gene prognostic signatures have been demonstrated to be highly efficient in predicting the prognosis, immune microenvironment, gene mutation status, immunotherapy response, and chemotherapeutic sensitivity of HNSCC patients.
Subject(s)
Head and Neck Neoplasms , Humans , Squamous Cell Carcinoma of Head and Neck/genetics , Squamous Cell Carcinoma of Head and Neck/therapy , Prognosis , Kaplan-Meier Estimate , Head and Neck Neoplasms/diagnosis , Head and Neck Neoplasms/genetics , Head and Neck Neoplasms/therapy , Ion Channels/genetics , Tumor Microenvironment/genetics , NAV1.4 Voltage-Gated Sodium ChannelABSTRACT
Background: This network meta-analysis aimed to comprehensively compare the operative and postoperative outcomes of different parotidectomy incisions. Methods: Embase, PubMed, Web of Science, and Cochrane Central Register of Controlled Trials were searched up to April 2022. A complete Bayesian network meta-analysis was performed using the Markov Monte Carlo method in OpenBUGS. Results: Seventeen studies with 1609 patients were included. Thirteen were retrospective cohort studies, three were prospective cohort studies, and one was a randomized controlled study. The quality of evidence was rated as very low in most comparisons. The incision satisfaction score of the modified facelift incision (MFI), retroauricular hairline incision (RAHI), V-shaped incision (VI) were higher than that of the modified Blair incision (MBI) (MBI vs. MFI: mean difference [MD] -1.39; 95% credible interval [CrI] -2.23, -0.57) (MBI vs. RAHI: MD -2.25; 95% CrI -3.40, -1.12) (MBI vs. VI: MD -2.58; 95% CrI -3.71, -1.46); the tumor size treated by VI was smaller than that by MBI (MD 5.15; 95% CrI 0.76, 9.38) and MFI (MD 5.16; 95% CrI 0.34, 9.86); and the risk of transient facial palsy in the MFI was lower than that in the MBI (OR 2.13; 95% CrI 1.28, 3.64). There were no differences in operation time, drainage volume, wound infection, hematoma, salivary complications, Frey syndrome, or permanent facial palsy between incision types. Conclusion: The traditional MBI is frequently used for large tumor volumes, but the incision satisfaction score is low and postoperative complication control is poor. However, emerging incisions performed well in terms of incision satisfaction scores and control of complications. More randomized controlled trials are needed to compare the different parotidectomy incisions. Patients should be fully informed about the characteristics of each incision to make the most informed decision, along with the physician's advice. Systematic Review Registration: PROSPERO, identifier CRD42022331756.
ABSTRACT
In the original publication of this article, wrong western blot images were inadvertently included in Fig. 2 and Fig. 3. The corrected figures are shown below. The authors declare that these amendments do not change the results or conclusions of their paper, and apologize for this oversight.
ABSTRACT
The prognosis of patients with breast cancer is closely related to both the infiltration of immune cells and the expression of lncRNAs. In this study, we evaluated the infiltration of immune cells in 1109 breast cancer samples obtained from TCGA by applying the ssGSEA to the transcriptome of these samples, thereby generating high immune cell infiltration group and low immune cell infiltration group. On the basis of these groupings, we found 696 differentially expressed lncRNAs which were sequentially subjected to univariate Cox regression and stepwise multiple Cox regression analysis. 11 lncRNAs were identified as prognostic signature for breast cancer. Kaplan-Meier analysis, univariate Cox regression, multivariate Cox regression, and ROC analyses further revealed that this 11-lncRNA signature was a novel and important prognostic factor independent of multiple clinicopathological parameters. The TIMER database showed that this 11-lncRNA prognostic signature for breast cancer was associated with the infiltration of immune cell subtypes.
Subject(s)
Breast Neoplasms/genetics , Breast Neoplasms/immunology , RNA, Long Noncoding/metabolism , Breast Neoplasms/mortality , Breast Neoplasms/pathology , Female , Humans , Immune System/metabolism , Kaplan-Meier Estimate , PrognosisABSTRACT
Patients with non-small-cell lung cancer (NSCLC) are routinely treated with the platinum-based chemotherapeutics such as cisplatin. The drug exerts anticancer effects via multiple mechanisms, including DNA double-strand breaks (DSBs). Enhanced DNA DSB repair capacity would be associated with innate or acquired drug resistance. However, despite strong evidence for the role of the chromokinesin kinesin family member 4A (KIF4A) in DSB repair, the relationship between the chromokinesin and cisplatin sensitivity of human NSCLC cells remains unknown. Furthermore, little is known regarding the effect of targeting KIF4A on the function of DSB repair-related proteins in these cells. In the current study, we demonstrated that cisplatin treatment stimulated the expression of KIF4A protein in human NSCLC cells. Depletion of KIF4A by small interfering RNA significantly enhanced cisplatin-induced cell cycle arrest in S and G2/M phases and cytotoxicity in human NSCLC cells. Furthermore, we found that KIF4A inhibition suppressed the ability of cisplatin to induce BRCA2 and Rad51 focus formation and limits the further increase in poly(ADP-ribose) polymerase 1 activity induced by cisplatin treatment in human NSCLC cells. These studies thus identify the chromokinesin KIF4A as a novel modulator of cisplatin sensitivity that is significantly enhanced by the chromokinesin in human NSCLC cells via multiple mechanisms.
Subject(s)
Carcinoma, Non-Small-Cell Lung/drug therapy , Cisplatin/pharmacology , DNA Breaks, Double-Stranded/drug effects , DNA Repair/drug effects , DNA/drug effects , Kinesins/metabolism , Lung Neoplasms/drug therapy , Antineoplastic Agents/pharmacology , BRCA2 Protein/metabolism , Carcinoma, Non-Small-Cell Lung/metabolism , Cell Cycle Checkpoints/drug effects , Cell Line , Cell Line, Tumor , DNA-Binding Proteins/metabolism , HEK293 Cells , Humans , Lung Neoplasms/metabolism , Nuclear Proteins/metabolism , Poly (ADP-Ribose) Polymerase-1/metabolism , Rad51 Recombinase/metabolismABSTRACT
In this study, we demonstrated that PUMA was involved in the microglial migration induced by methamphetamine. PUMA expression was examined by western blotting and immunofluorescence staining. BV2 and HAPI cells were pretreated with a sigma-1R antagonist and extracellular signal-regulated kinase (ERK), mitogen-activated protein kinase (MAPK), c-Jun N-terminal protein kinase (JNK), and phosphatidylinositol-3 kinase (PI3K)/Akt inhibitors, and PUMA expression was detected by western blotting. The cell migration in BV2 and HAPI cells transfected with a lentivirus encoding red fluorescent protein (LV-RFP) was also examined using a wound-healing assay and nested matrix model and cell migration assay respectively. The molecular mechanisms of PUMA in microglial migration were validated using a siRNA approach. The exposure of BV2 and HAPI cells to methamphetamine increased the expression of PUMA, reactive oxygen species (ROS), the MAPK and PI3K/Akt pathways and the downstream transcription factor signal transducer and activator of transcription 3 (STAT3) pathways. PUMA knockdown in microglia transfected with PUMA siRNA attenuated the increased cell migration induced by methamphetamine, thereby implicating PUMA in the migration of BV2 and HAPI cells. This study demonstrated that methamphetamine-induced microglial migration involved PUMA up-regulation. Targeting PUMA could provide insights into the development of a potential therapeutic approach for the alleviation of microglia migration induced by methamphetamine.
Subject(s)
Apoptosis Regulatory Proteins/metabolism , Cell Movement/drug effects , Central Nervous System Stimulants/pharmacology , Methamphetamine/pharmacology , Microglia/metabolism , Proto-Oncogene Proteins/metabolism , Animals , Cell Line , Humans , Mice , Microglia/cytology , Microglia/drug effects , Oxidative Stress/drug effects , Reactive Oxygen Species/metabolism , Receptors, sigma/metabolism , Signal Transduction/drug effects , Sigma-1 ReceptorABSTRACT
Metastatic spread of cancer cells is the most life-threatening aspect of breast cancer and involves multiple steps including cell migration. We recently found that the TBC1D3 oncogene promotes the migration of breast cancer cells, and its interaction with CaM enhances the effects of TBC1D3. However, little is known regarding the mechanism by which TBC1D3 induces the migration of cancer cells. Here, we demonstrated that TBC1D3 stimulated the expression of oxidized low density lipoprotein receptor 1 (OLR1), a stimulator of cell migration, in breast cancer cells at the transcriptional level. Depletion of OLR1 by siRNAs or down-regulation of OLR1 expression using pomalidomide, a TNFα inhibitor, significantly decreased TBC1D3-induced migration of these cells. Notably, TBC1D3 overexpression activated NF-κB, a major effector of TNFα signaling, while inhibition of TNFα signaling suppressed the effects of TBC1D3. Consistent with this, NF-κB inhibition using its specific inhibitor caffeic acid phenethyl ester decreased both TBC1D3-induced OLR1 expression and cell migration, suggesting a critical role for TNFα/NF-κB signaling in TBC1D3-induced migration of breast cancer cells. Mechanistically, TBC1D3 induced activation of this signaling pathway on multiple levels, including by increasing the release of TNFα, elevating the transcription of TNFR1, TRAF1, TRAF5 and TRAF6, and decreasing the degradation of TNFR1. In summary, these studies identify the TBC1D3 oncogene as a novel regulator of TNFα/NF-κB signaling that mediates this oncogene-induced migration of human breast cancer cells by up-regulating OLR1.
Subject(s)
Breast Neoplasms/drug therapy , Cell Movement , GTPase-Activating Proteins/metabolism , NF-kappa B/metabolism , Proto-Oncogene Proteins/metabolism , Scavenger Receptors, Class E/metabolism , Tumor Necrosis Factor-alpha/metabolism , Apoptosis , Breast Neoplasms/enzymology , Breast Neoplasms/pathology , Cell Proliferation , Female , GTPase-Activating Proteins/genetics , Gene Expression Regulation, Neoplastic , Humans , NF-kappa B/genetics , Proto-Oncogene Proteins/genetics , RNA, Small Interfering/genetics , Scavenger Receptors, Class E/antagonists & inhibitors , Scavenger Receptors, Class E/genetics , Tumor Cells, Cultured , Tumor Necrosis Factor-alpha/geneticsABSTRACT
The hominoid oncoprotein TBC1D3 enhances growth factor (GF) signaling and GF signaling, conversely, induces the ubiquitination and subsequent degradation of TBC1D3. However, little is known regarding the regulation of this degradation, and the role of TBC1D3 in the progression of tumors has also not been defined. In the present study, we demonstrated that calmodulin (CaM), a ubiquitous cellular calcium sensor, specifically interacted with TBC1D3 in a Ca2+-dependent manner and inhibited GF signaling-induced ubiquitination and degradation of the oncoprotein in both cytoplasm and nucleus of human breast cancer cells. The CaM-interacting site of TBC1D3 was mapped to amino acids 157~171, which comprises two 1-14 hydrophobic motifs and one lysine residue (K166). Deletion of these motifs was shown to abolish interaction between TBC1D3 and CaM. Surprisingly, this deletion mutation caused inability of GF signaling to induce the ubiquitination and subsequent degradation of TBC1D3. In agreement with this, we identified lysine residue 166 within the CaM-interacting motifs of TBC1D3 as the actual site for the GF signaling-induced ubiquitination using mutational analysis. Point mutation of this lysine residue exhibited the same effect on TBC1D3 as the deletion mutant, suggesting that CaM inhibits GF signaling-induced degradation of TBC1D3 by occluding its ubiquitination at K166. Notably, we found that TBC1D3 promoted the expression and activation of MMP-9 and the migration of MCF-7 cells. Furthermore, interaction with CaM considerably enhanced such effect of TBC1D3. Taken together, our work reveals a novel model by which CaM promotes cell migration through inhibiting the ubiquitination and degradation of TBC1D3.
Subject(s)
Breast Neoplasms/metabolism , Calmodulin/metabolism , GTPase-Activating Proteins/metabolism , Matrix Metalloproteinase 9/metabolism , Proto-Oncogene Proteins/metabolism , Binding Sites , Breast Neoplasms/genetics , Calcium/metabolism , Cell Line, Tumor , Cell Movement , Cell Nucleus/metabolism , Cytoplasm/metabolism , Female , GTPase-Activating Proteins/chemistry , GTPase-Activating Proteins/genetics , Gene Expression Regulation, Neoplastic , Humans , Matrix Metalloproteinase 9/genetics , Mutation , Protein Binding , Proteolysis , Proto-Oncogene Proteins/chemistry , Proto-Oncogene Proteins/genetics , Signal Transduction , UbiquitinationABSTRACT
The hominoid oncogene TBC1D3 enhances epidermal growth factor receptor (EGFR) signaling and induces cell transformation. However, little is known regarding its spatio-temporal regulation and mechanism of tumorigenesis. In the current study, we identified the microtubule subunit ß-tubulin as a potential interaction partner for TBC1D3 using affinity purification combined with mass spectrometry analysis. The interaction between TBC1D3 and ß-tubulin was confirmed by co-immunoprecipitation. Using the same method, we also revealed that TBC1D3 co-precipitated with endogenous α-tubulin, another subunit of the microtubule. In agreement with these results, microtubule cosedimentation assays showed that TBC1D3 associated with the microtubule network. The ß-tubulin-interacting site of TBC1D3 was mapped to amino acids 286â¼353 near the C-terminus of the TBC domain. Deletion mutation within these amino acids was shown to abolish the interaction of TBC1D3 with ß-tubulin. Interestingly, the deletion mutation caused a complete loss of TBC1D3 from the cytoplasmic filamentous and punctate structures, and TBC1D3 instead appeared in the nucleus. Consistent with this, wild-type TBC1D3 exhibited the same nucleocytoplasmic distribution in cells treated with the microtubule depolymerizing agent nocodazole, suggesting that the microtubule network associates with and retains TBC1D3 in the cytoplasm. We further found that deficiency in ß-tubulin-interacting resulted in TBC1D3's inability to inhibit c-Cbl recruitment and EGFR ubiquitination, ultimately leading to dysregulation of EGFR degradation and signaling. Taken together, these studies indicate a novel model by which the microtubule network regulates EGFR stability and signaling through tubulin dimer/oligomer interaction with the nucleocytoplasmic protein TBC1D3.
Subject(s)
Cytoplasm/metabolism , ErbB Receptors/metabolism , GTPase-Activating Proteins/metabolism , Microtubules/metabolism , Proto-Oncogene Proteins/metabolism , Signal Transduction/physiology , Cell Line, Tumor , Cell Proliferation/physiology , Humans , Tubulin/metabolismABSTRACT
The TRE17 (USP6/TRE-2) oncogene induces tumorigenesis in both humans and mice. However, little is known regarding its regulation or mechanism of transformation. TRE17 encodes a TBC (Tre-2/Bub2/Cdc16)/Rab GTPase-activating protein homology domain at its N terminus and a ubiquitin-specific protease at its C terminus. In the current study, we identified the ubiquitous calcium (Ca2+)-binding protein calmodulin (CaM) as a novel binding partner for TRE17. CaM bound directly to TRE17 in a Ca2+-dependent manner both in vitro and in vivo. The CaM-binding site was mapped to two hydrophobic motifs near the C terminus of the TBC domain. Point mutations within these motifs significantly reduced the interaction of TRE17 with CaM. We further found that TRE17 is monoubiquitinated and promotes its own deubiquitination in vivo. CaM binding-deficient mutants of TRE17 exhibited significantly reduced monoubiquitination, suggesting that binding of Ca2+/CaM to TRE17 promotes this modification. Consistent with this notion, treatment of cells with the CaM inhibitor W7 reduced levels of TRE17 monoubiquitination. Interestingly, the calcium ionophore A23187 induced accumulation of a polyubiquitinated TRE17 species. The effect of A23187 was attenuated in CaM binding-deficient mutants of TRE17. Taken together, these studies indicate a role for Ca2+/CaM in regulating ubiquitination through direct interaction with TRE17.
Subject(s)
Calcium/metabolism , Calmodulin/metabolism , Endopeptidases/physiology , Oncogene Proteins/physiology , Ubiquitin/metabolism , Amino Acid Motifs , Binding Sites , Calcimycin/pharmacology , DNA, Complementary/metabolism , Endopeptidases/metabolism , GTPase-Activating Proteins/metabolism , Glutathione Transferase/metabolism , HeLa Cells , Humans , Immunoprecipitation , In Vitro Techniques , Ionophores/pharmacology , Mutation , Oncogene Proteins/metabolism , Protein Binding , Protein Isoforms , Protein Structure, Tertiary , Proto-Oncogene Proteins , Signal Transduction , Ubiquitin ThiolesteraseABSTRACT
BACKGROUND: Peroxiredoxins (Prxs) are antioxidant enzymes expressed by most free-living organisms, often in multiple isoforms. Because mammalian Prxs have not been experimentally deleted or inhibited, it is not known how much they contribute to antioxidant defense, nor whether the multiple isoforms afford redundant or additive protection. MATERIALS AND METHODS: Expression of the four members of the 2-Cys family of human Prxs was tested in human tumor cell lines. Monospecific antibodies were developed and used to monitor the extent and specificity of inhibition of expression of each isoform in prostate cancer cells stably transfected with antisense constructs. RESULTS: Seventeen tumor lines transcribed genes for all four human Prxs. Prostate cancer cells coexpressed each isoform at the protein level. Stable transfection with antisense allowed partial, selective suppression of Prx 1, 2, 3, or 4. Prostate cancer cells were rendered more sensitive to hydrogen peroxide or an organic hydroperoxide when Prx 1, 2, or 3 but not 4 was partially suppressed, bringing them into the range of sensitivity of mouse cells. The effect of partially suppressing a single Prx was comparable to that of depleting glutathione. In contrast, sensitization to adriamycin, an antitumor agent with a redox-active quinone, followed the partial suppression of Prxs 1, 2, or 4 but not 3. Individual suppression of Prxs 1-4 had no effect on sensitivity of the cells to reactive nitrogen intermediates, tumor necrosis factor (TNF), paclitaxel (Taxol), or etoposide. CONCLUSIONS: The 2-Cys Prxs act in a mutually nonredundant and sometimes stress-specific fashion to protect human cells from oxidant injury. The substantial resistance of human cells to hydroperoxides may result in part from the additive action of multiple Prxs.