scholarly journals A Regulatory Loop of FBXW7-MYC-PLK1 Controls Tumorigenesis of MYC-Driven Medulloblastoma

Cancers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 387
Author(s):  
Dong Wang ◽  
Angela Pierce ◽  
Bethany Veo ◽  
Susan Fosmire ◽  
Etienne Danis ◽  
...  
Keyword(s):  
Tumor Development ◽  
Tumor Suppressor Function ◽  
Protein Levels ◽  
Group 3 ◽  
Induced Apoptosis ◽  
Regulatory Loop ◽  
Proliferation In Vitro ◽  
Constitutive Phosphorylation

Polo-like kinase 1 (PLK1) is highly expressed in group 3 medulloblastoma (MB), and it has been preclinically validated as a cancer therapeutic target in medulloblastoma. Here, we demonstrate that PLK1 inhibition with PCM-075 or BI6727 significantly reduces the growth of MB cells and causes a decrease of c-MYC mRNA and protein levels. We show that MYC activates PLK1 transcription, while the inhibition of PLK1 suppresses MB tumor development and causes a decrease in c-MYC protein level by suppressing FBXW7 auto poly-ubiquitination. FBXW7 physically interacts with PLK1 and c-MYC, facilitating their protein degradation by promoting ubiquitination. These results demonstrate a PLK1-FBXW7-MYC regulatory loop in MYC-driven medulloblastoma. Moreover, FBXW7 is significantly downregulated in group 3 patient samples. The overexpression of FBXW7 induced apoptosis and suppressed proliferation in vitro and in vivo, while constitutive phosphorylation mutation attenuated its tumor suppressor function. Altogether, these findings demonstrated that PLK1 inhibition stabilizes FBXW7 in MYC-driven MB, thus revealing an important function of FBXW7 in suppressing medulloblastoma progression.

scholarly journals MBRS-65. FBXW7 ACTS A TUMOR SUPPRESSOR IN MYC-DRIVEN MEDULLOBLASTOMA BY CONTROLLING A FEED-FORWARD REGULATORY LOOP OF PLK1 AND MYC

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii409-iii409
Author(s):  
Dong Wang ◽  
Angela Pierce ◽  
Bethany Veo ◽  
Susan Fosmire ◽  
Krishna Madhavan ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Kinase Inhibitors ◽  
Proteasomal Degradation ◽  
Tumor Suppressor Function ◽  
Group 3 ◽  
Regulatory Loop ◽  
Proliferation In Vitro ◽  
Lower Expression

Abstract Group 3 medulloblastoma (MB) is often accompanied by MYC amplification and has a higher rate of metastatic disease. So, it is critical to have more effective therapies for high MYC expressing sub-groups. Here we report that FBXW7, a substrate recognition component of the SKP1-CUL1-Fbox (SCF) E3 ligase, interacts with and targets c-MYC for polyubiquitination and proteasomal degradation. FBXW7 shows lower expression level in MYC-driven MB compared with other MB subgroups suggesting activity as a tumor suppressor. Genomic deletion or mutation of Fbxw7 has frequently been identified in many human cancers but not in MB. We demonstrate that overexpression of Fbxw7 in MB cells induces apoptosis and suppresses proliferation in vitro and in vivo. Both phospho-deficient (T205A) and phosphomimetic aspartic acid (T205D) mutants deactivate its tumor suppressor function suggesting a conformational change of its protein structure. Mechanistically, PLK1 kinase specifically phosphorylates FBXW7 and promotes its auto-polyubiquitination and proteasomal degradation, counteracting FBXW7-mediated degradation of oncogene substrates, including c-MYC and PLK1. Chip-Seq results show stabilized c-MYC in turn directly activates PLK1 and FBXW7 transcription, constituting a feedforward regulatory loop. Co-immunoprecipitation demonstrates that FBXW7 directly binds to PLK1 and c-MYC, facilitating their protein degradation by promoting the ubiquitination of both proteins. Furthermore, we show that FBXW7 protein can be stabilized by various kinase inhibitors, proposing a mechanism of kinase-targeted agents to treat MYC-driven MB. These results collectively demonstrate how kinase inhibition stabilizes the tumor suppressor FBXW7 in MYC-driven MB, thus revealing an important function of FBXW7 in suppressing MB progression.

scholarly journals HNRNPA2B1 promotes multiple myeloma progression by increasing AKT3 expression via m6A-dependent stabilization of ILF3 mRNA

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Fengjie Jiang ◽  
Xiaozhu Tang ◽  
Chao Tang ◽  
Zhen Hua ◽  
Mengying Ke ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Proliferation ◽  
Cellular Proliferation ◽  
Aberrant Expression ◽  
The Stability ◽  
Induced Apoptosis ◽  
Proliferation In Vitro

AbstractN6-methyladenosine (m6A) modification is the most prevalent modification in eukaryotic RNAs while accumulating studies suggest that m6A aberrant expression plays an important role in cancer. HNRNPA2B1 is a m6A reader which binds to nascent RNA and thus affects a perplexing array of RNA metabolism exquisitely. Despite unveiled facets that HNRNPA2B1 is deregulated in several tumors and facilitates tumor growth, a clear role of HNRNPA2B1 in multiple myeloma (MM) remains elusive. Herein, we analyzed the function and the regulatory mechanism of HNRNPA2B1 in MM. We found that HNRNPA2B1 was elevated in MM patients and negatively correlated with favorable prognosis. The depletion of HNRNPA2B1 in MM cells inhibited cell proliferation and induced apoptosis. On the contrary, the overexpression of HNRNPA2B1 promoted cell proliferation in vitro and in vivo. Mechanistic studies revealed that HNRNPA2B1 recognized the m6A sites of ILF3 and enhanced the stability of ILF3 mRNA transcripts, while AKT3 downregulation by siRNA abrogated the cellular proliferation induced by HNRNPA2B1 overexpression. Additionally, the expression of HNRNPA2B1, ILF3 and AKT3 was positively associated with each other in MM tissues tested by immunohistochemistry. In summary, our study highlights that HNRNPA2B1 potentially acts as a therapeutic target of MM through regulating AKT3 expression mediated by ILF3-dependent pattern.

scholarly journals P11.17 Splicing dysregulation drives glioblastoma malignancy: SRSF3 as a potential therapeutic target to impair glioblastoma progression

2019 ◽  
Vol 21 (Supplement_3) ◽  
pp. iii46-iii46
Author(s):  
A C Fuentes-Fayos ◽  
M C Vázquez-Borrego ◽  
J M Jiménez-Vacas ◽  
L Bejarano ◽  
C Blanco-Acevedo ◽  
...  
Keyword(s):  
Therapeutic Target ◽  
Tumor Development ◽  
Microarray Dataset ◽  
Oncogenic Signaling ◽  
Potential Therapeutic Target ◽  
Induced Apoptosis ◽  
Perfect Discrimination ◽  
Control Samples

Abstract Glioblastomas (GBMs) remain the deadliest human brain tumors, with poor prognosis despite years of research. Currently, standard therapeutic strategies to treat GBM are not efficient and common survival from diagnosis is ~12–16 months. Thus, identification of new diagnostic/prognostic/therapeutic tools to tackle GBMs is crucial. Emerging evidence indicates that the cellular machinery controlling alternative splicing is altered in tumor pathologies, leading to oncogenic splicing events linked to tumor progression. Accordingly, we aimed to determine the expression pattern of the spliceosome components (SCs) and splicing factors (SFs) in high-grade astrocytomas (HGAs), mostly GBMs, and to ascertain the potential consequences of its dysregulation on GBM development. To this end, expression levels of SCs core and selected SFs were measured using a customized-microfluidic qPCR array in a well-characterized cohort of HGAs (n=33). Our results unveiled a profound alteration in the expression of multiple SCs and SFs in HGAs compared to healthy brain control-samples, wherein levels of particular elements (SRSF3/RBM22/PTBP1/RBM3) enabled perfect discrimination between non-pathological vs. tumor human-tissues, and between proneural and mesenchymal-like GBMs vs. control samples in mouse-models. Results were confirmed in an independent validation-cohort (n=49) and available Microarray dataset (Murat), which revealed that the expression of these splicing elements was correlated with relevant tumor markers and with survival. Remarkably, SRSF3/RBM22/PTBP1/RBM3 silencing (using specific siRNAs) decreased several aggressiveness parameters in vitro (e.g. proliferation, migration, tumorsphere formation, VEGFA secretion, etc.) and induced apoptosis, being SRSF3 the most relevant element affecting these parameters. Hence, a preclinical mouse model (U87MG-xenografts) with SRSF3 silencing drastically decreased in vivo tumor development/progression (i.e. tumor size, %MKI67, mitosis number, etc.) likely through a molecular/cellular mechanism involving the regulation of PDGFRB expression and its associated oncogenic signaling pathways. Overall, our results demonstrate that there is a profound dysregulation of the splicing machinery (spliceosome core and SFs) in HGAs/GBMs, which is directly associated to the development/progression of GBMs. Furthermore, this study reveals that SRSF3 can be a novel biomarker of malignancy and a potential therapeutic target to impair GBMs progression.

scholarly journals Upregulated TRIM11 Exerts its Oncogenic Effects in Hepatocellular Carcinoma Through Inhibition of P53

2017 ◽  
Vol 44 (1) ◽  
pp. 255-266 ◽  
Author(s):  
Jinjin Liu ◽  
Jun Rao ◽  
Xuming Lou ◽  
Jian Zhai ◽  
Zhenhua Ni ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Tumor Development ◽  
Tumor Model ◽  
Migration And Invasion ◽  
P53 Expression ◽  
Protein Levels ◽  
Normal Tissues ◽  
P53 Signaling

Background/Aims: The tripartite motif containing (TRIM) family plays crucial roles in tumor development and progression. However, little is known about the function and mechanism of TRIM11 in hepatocellular carcinoma (HCC). Methods: The expression levels of TRIM11 were examined by real-time PCR, Western blot and Immunohistochemical (IHC) staining. TRIM11 knockdown cells were produced by lentivirus infection, and functional assays, such as MTT, colony formation assay, migration and invasion assays and a xenograft tumor model were used to investigate the role of TRIM11 in HCC. We also determined the effect of TRIM11 on p53 signaling and its downstream molecules. Results: We found that TRIM11 mRNA and protein levels were significantly increased in HCC tissues as compared with normal tissues; increased levels correlated with poor patient survival. By loss- and gain-of-function investigations, knockdown of TRIM11 suppressed cell proliferation, migration, invasion in vitro and tumor growth in vivo. Moreover, TRIM11 negatively regulated p53 expression. Knockdown of p53 abrogated the in vitro and in vivo biological functions of TRIM11 shRNA in HCC cells. Conclusions: These data show that TRIM11 exerts its oncogenic effect in HCC by downregulating p53 both in vitro and in vivo. Our data provide new insights into the pathogenesis of HCC and indicate that TRIM11 may serve as a new therapeutic target for HCC treatment.

Casticin Induced Apoptosis in A375.S2 Human Melanoma Cells through the Inhibition of NF-κB and Mitochondria-Dependent Pathways In Vitro and Inhibited Human Melanoma Xenografts in a Mouse Model In Vivo

2016 ◽  
Vol 44 (03) ◽  
pp. 637-661 ◽  
Author(s):  
Yin-Wen Shiue ◽  
Chi-Cheng Lu ◽  
Yu-Ping Hsiao ◽  
Ching-Lung Liao ◽  
Jing-Pin Lin ◽  
...  
Keyword(s):  
Human Melanoma ◽  
Oxygen Species ◽  
Protein Levels ◽  
Phase Arrest ◽  
Viable Cells ◽  
M Phase ◽  
Induced Apoptosis ◽  
Western Blotting Assay

Casticin, a polymethoxyflavone occurring in natural plants, has been shown to have anticancer activities. In the present study, we aims to investigate the anti-skin cancer activity of casticin on melanoma cells in vitro and the antitumor effect of casticin on human melanoma xenografts in nu/nu mice in vivo. A flow cytometric assay was performed to detect expression of viable cells, cell cycles, reactive oxygen species production, levels of [Formula: see text] and caspase activity. A Western blotting assay and confocal laser microscope examination were performed to detect expression of protein levels. In the in vitro studies, we found that casticin induced morphological cell changes and DNA condensation and damage, decreased the total viable cells, and induced G2/M phase arrest. Casticin promoted reactive oxygen species (ROS) production, decreased the level of [Formula: see text], and promoted caspase-3 activities in A375.S2 cells. The induced G2/M phase arrest indicated by the Western blotting assay showed that casticin promoted the expression of p53, p21 and CHK-1 proteins and inhibited the protein levels of Cdc25c, CDK-1, Cyclin A and B. The casticin-induced apoptosis indicated that casticin promoted pro-apoptotic proteins but inhibited anti-apoptotic proteins. These findings also were confirmed by the fact that casticin promoted the release of AIF and Endo G from mitochondria to cytosol. An electrophoretic mobility shift assay (EMSA) assay showed that casticin inhibited the NF-[Formula: see text]B binding DNA and that these effects were time-dependent. In the in vivo studies, results from immuno-deficient nu/nu mice bearing the A375.S2 tumor xenograft indicated that casticin significantly suppressed tumor growth based on tumor size and weight decreases. Early G2/M arrest and mitochondria-dependent signaling contributed to the apoptotic A375.S2 cell demise induced by casticin. In in vivo experiments, A375.S2 also efficaciously suppressed tumor volume in a xenotransplantation model. Therefore, casticin might be a potential therapeutic agent for the treatment of skin cancer in the future.

scholarly journals Splicing machinery dysregulation drives glioblastoma development/aggressiveness: oncogenic role of SRSF3

Brain ◽  
2020 ◽  
Vol 143 (11) ◽  
pp. 3273-3293
Author(s):  
Antonio C Fuentes-Fayos ◽  
Mari C Vázquez-Borrego ◽  
Juan M Jiménez-Vacas ◽  
Leire Bejarano ◽  
Sergio Pedraza-Arévalo ◽  
...  
Keyword(s):  
Patient Survival ◽  
Tumour Progression ◽  
Protein Levels ◽  
Cellular Machinery ◽  
Therapeutic Tools ◽  
Induced Apoptosis ◽  
Control Samples ◽  
Splicing Machinery

Abstract Glioblastomas remain the deadliest brain tumour, with a dismal ∼12–16-month survival from diagnosis. Therefore, identification of new diagnostic, prognostic and therapeutic tools to tackle glioblastomas is urgently needed. Emerging evidence indicates that the cellular machinery controlling the splicing process (spliceosome) is altered in tumours, leading to oncogenic splicing events associated with tumour progression and aggressiveness. Here, we identify for the first time a profound dysregulation in the expression of relevant spliceosome components and splicing factors (at mRNA and protein levels) in well characterized cohorts of human high-grade astrocytomas, mostly glioblastomas, compared to healthy brain control samples, being SRSF3, RBM22, PTBP1 and RBM3 able to perfectly discriminate between tumours and control samples, and between proneural-like or mesenchymal-like tumours versus control samples from different mouse models with gliomas. Results were confirmed in four additional and independent human cohorts. Silencing of SRSF3, RBM22, PTBP1 and RBM3 decreased aggressiveness parameters in vitro (e.g. proliferation, migration, tumorsphere-formation, etc.) and induced apoptosis, especially SRSF3. Remarkably, SRSF3 was correlated with patient survival and relevant tumour markers, and its silencing in vivo drastically decreased tumour development and progression, likely through a molecular/cellular mechanism involving PDGFRB and associated oncogenic signalling pathways (PI3K-AKT/ERK), which may also involve the distinct alteration of alternative splicing events of specific transcription factors controlling PDGFRB (i.e. TP73). Altogether, our results demonstrate a drastic splicing machinery-associated molecular dysregulation in glioblastomas, which could potentially be considered as a source of novel diagnostic and prognostic biomarkers as well as therapeutic targets for glioblastomas. Remarkably, SRSF3 is directly associated with glioblastoma development, progression, aggressiveness and patient survival and represents a novel potential therapeutic target to tackle this devastating pathology.

scholarly journals Phospholipase D1 Ameliorates Apoptosis in Chronic Renal Toxicity Caused by Low-Dose Cadmium Exposure

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Ke Huang ◽  
Yaotang Deng ◽  
Wenya Yuan ◽  
Jian Geng ◽  
Guanghai Wang ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Kidney Tissue ◽  
Kidney Injury ◽  
Sprague Dawley ◽  
Protein Levels ◽  
Phospholipase D1 ◽  
Induced Apoptosis ◽  
Kidney Impairment

Exposure to cadmium (Cd), a common heavy metal used in industry, can result in long-term chronic toxicity. It has been well characterized that kidneys are the main organs that are targeted by toxicity, which can cause apoptosis, necrosis, and atrophy of renal tubular epithelial cells. However, the molecular mechanisms associated with Cd toxicity remain unclear. In this study, the expression of renal proteins in Sprague-Dawley rats exposed to chronic Cd was analyzed with iTRAQ proteomics. Bioinformatics analysis indicated that phospholipase D1 (PLD1) was significantly underexpressed and may correlate strongly with Cd-induced chronic kidney impairment. Previous studies have shown that PLD1 promotes cell proliferation and inhibits apoptosis, indicating that PLD1 may be implicated in the pathogenesis of kidney injury induced by Cd. Studies in vivo and in vitro all demonstrate that the mRNA and protein levels of PLD1 decrease significantly both in kidney tissue and in proximal tubular cell lines exposed to Cd. Overexpression of PLD1 and its downstream product PA could ameliorate Cd-induced apoptosis. Moreover, we identified that miR-122-5p was a regulatory miRNA of PLD1. miR-122-5p was overexpressed after Cd exposure and promoted cell apoptosis by downregulating PLD1 through binding the 3′UTR of the locus at 1761–1784 nt. In conclusion, our results indicated that PLD1 and its downstream PA were strongly implicated in Cd-induced chronic kidney impairment and could be a novel player in the defense against Cd-induced nephrotoxicity.

scholarly journals The long non-coding RNA lnc-HLX-2-7 is oncogenic in group 3 medulloblastomas

2020 ◽  
Author(s):  
Keisuke Katsushima ◽  
Bongyong Lee ◽  
Haritha Kunhiraman ◽  
Cuncong Zhong ◽  
Rabi Murath ◽  
...  
Keyword(s):  
Rna Sequencing ◽  
Therapeutic Target ◽  
Rna Seq ◽  
Potential Therapeutic Target ◽  
Non Coding Rna ◽  
Group 3 ◽  
Induced Apoptosis ◽  
Long Non Coding Rna

AbstractBackgroundMedulloblastoma (MB) is an aggressive brain tumor that predominantly affects children. Recent high-throughput sequencing studies suggest that the non-coding RNA genome, in particular long non-coding RNAs (lncRNAs), contributes to MB sub-grouping. Here we report the identification of a novel lncRNA, lnc-HLX-2-7, as a potential molecular marker and therapeutic target in group 3 MBs.MethodsPublicly available RNA sequencing (RNA-seq) data from 175 MB patients were interrogated to identify lncRNAs that differentiate between MB subgroups. After characterizing a subset of differentially expressed lncRNAs in vitro and in vivo, the group 3-enriched lncRNA lnc-HLX2-7 was deleted by CRISPR/Cas9 in the MB cell line D425 Med. Intracranially injected tumors were further characterized by bulk and single-cell RNA-sequencing.Resultslnc-HLX-2-7 is highly upregulated in group 3 MB cell lines, patient-derived xenografts, and primary MBs compared to other MB sub-groups as assessed by qRT-PCR, RNA-seq, and RNA fluorescence in situ hybridization (FISH). Depletion of lnc-HLX-2-7 with antisense oligonucleotides or CRISPR/Cas9 significantly reduced cell proliferation and 3D colony formation and induced apoptosis. lnc-HLX-2-7-deleted D425 Med cells injected into mouse cerebella produced smaller tumors than those derived from parental cells. Pathway analysis revealed that lnc-HLX2-7 modulated oxidative phosphorylation, mitochondrial dysfunction, and sirtuin signaling pathways. The MYC oncogene regulated lnc-HLX-2-7, and the small molecule BET-bromodomain (BRD4) inhibitor JQ1 reduced lnc-HLX2-7 expression.Conclusionslnc-HLX-2-7 is oncogenic in MB and represents a promising novel molecular marker and a potential therapeutic target in group 3 MBs in children.Key pointslnc-HLX-2-7 is highly upregulated in group 3 medulloblastomas compared to other sub-groups.In vitro and in vivo studies strongly support an oncogenic role for lnc-HLX2-7 in group 3 medulloblastoma.lnc-HLX-2-7 may be a novel biomarker and a potential therapeutic target in group 3 medulloblastoma.Importance of the studyGroup 3 medulloblastomas are associated with poor clinical outcomes, are difficult to subtype clinically, and their biology is poorly understood. In an effort to address these problems, we identified a group 3-specific long non-coding RNA, lnc-HLX-2-7, in an in silico analysis of 175 medulloblastomas and confirmed its expression in group 3 medulloblastoma cell lines, patient-derived xenografts, and FFPE samples. CRISPR/Cas9 deletion and antisense oligonucleotide knockdown of lnc-HLX-2-7 significantly reduced cell growth and 3D colony formation and induced apoptosis. Deletion of lnc-HLX-2-7 in cells injected into mouse cerebellums reduced tumor growth compared to parental cells, and RNA sequencing of these tumors revealed lnc-HLX-2-7-associated modulation of cell viability and cell death signaling pathways. The oncogene MYC regulates lnc-HLX-2-7, and its expression can be controlled by the BET-bromodomain (BRD4) inhibitor JQ1. lnc-HLX-2-7 is a candidate biomarker and a potential therapeutic target in group 3 medulloblastomas in children.

scholarly journals Anticancer Properties and Mechanisms of Singly-Protonated Dehydronorcantharidin Silver Coordination Polymer in a Bladder Cancer Model

2021 ◽  
Vol 12 ◽  
Author(s):  
Changkuo Zhou ◽  
Ganyu Wang ◽  
Weiqiang Jing ◽  
Xuejie Tan ◽  
Hu Guo
Keyword(s):  
Bladder Cancer ◽  
Protein Levels ◽  
Anticancer Properties ◽  
G1 Phase Arrest ◽  
Bladder Cancer Cells ◽  
System Tumor ◽  
Induced Apoptosis ◽  
Effective Drugs

Bladder cancer is the most common malignant urinary system tumor. Chemotherapy is frequently used as a treatment regimen for patients with bladder cancer, however, new and effective drugs for bladder cancer need to be developed. The present study examined the effects and mechanisms of Ag-SP-DNC, a silver and singly-protonated dehydronorcantharidin complex, on bladder cancer in vitro and in vivo. It was identified that Ag-SP-DNC suppressed cell proliferation and induced apoptosis in bladder cancer cells in vitro, a suppression associated with G0/G1 phase arrest and elevated intracellular reactive oxygen species (ROS) levels. Furthermore, Ag-SP-DNC enhanced the cleaved caspase-3 levels, disrupted the mitochondrial transmembrane potential balance, and induced intracellular calcium overload. The Ag-SP-DNC-induced bladder cancer cell apoptosis was significantly decreased following treatment with a broad caspase inhibitor, zVAD-fmk. In addition, treatment of MB49 tumor-bearing mice with Ag-SP-DNC significantly inhibited tumor growth and decreased the anti-apoptosis and cell cycle promotion protein levels in the tumor. The results of the present study suggested that Ag-SP-DNC elicits a strong anticancer effect against bladder cancer, and can therefore be used as a promising treatment for bladder cancer.

scholarly journals 18 Peroxiredoxin1 is a therapeutic target in group-3 medulloblastoma

2018 ◽  
Vol 45 (S3) ◽  
pp. S16-S16
Author(s):  
BV. Sajesh ◽  
OH. Ngoc ◽  
R. Omar ◽  
H. Fediuk ◽  
L. Li ◽  
...  
Keyword(s):  
Dna Damage ◽  
Therapeutic Target ◽  
Oxidative Dna Damage ◽  
Tumor Burden ◽  
In Vivo Studies ◽  
Orthotopic Model ◽  
Group 3 ◽  
Induced Apoptosis

Group-3 medulloblastoma (MBL) is highly resistant to radiation (IR) and chemotherapy and has the worst prognosis. Hence, there is an urgent need to elucidate targets that sensitize these tumors to chemotherapy and IR. Employing standard assays for viability and sensitization to IR, we identified PRDX1 as a therapeutic target in Group-3 MBL. Specifically, targeting PRDX1 by RNAi or inhibition by Adenanthin led to specific killing and sensitization to IR of Group-3 MBL cells. We rescued sensitization of Daoy and UW228 cells by hypermorphic expression of PRDX1. PRDX1 knockdown caused oxidative DNA damage and induced apoptosis. We correlated PRDX1 expression to patient outcomes in a validated MBL tumor-microarray. Whole genome sequencing identified pathways/genes that were dysregulated with PRDX1 inhibition or silencing. Our in vivo studies in mice employing flank/orthotopic tumors from patient derived xenografts/Group-3 MBL cells confirmed in vitro observations. Animals with tumors in which PRDX1 was targeted by RNAi or Adenanthin (using mini osmotic pumps) showed decreased tumor burden and increased survival when compared to controls. Since, Adenanthin does not cross the blood brain barrier (BBB) we used HAV6 peptide to transiently disrupt the BBB and deliver Adenanthin to the tumor. Immunohistochemistry confirmed that targeting PRDX1 resulted in increased oxidative DNA damage, apoptosis and decreased proliferation. In summary, we have validated PRDX1 as a therapeutic target in group-3 MBL, identified Adenanthin as a potent chemical inhibitor of PRDX1 and confirmed the role of HAV peptide (in the transient modulation of BBB permeability) in an orthotopic model of group-3 MBL.

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