Small-Molecule Activation of p53 Blocks Hypoxia-Inducible Factor 1α and Vascular Endothelial Growth Factor Expression In Vivo and Leads to Tumor Cell Apoptosis in Normoxia and Hypoxia

ABSTRACT The p53 tumor suppressor protein negatively regulates hypoxia-inducible factor 1α (HIF-1α). Here, we show that induction of p53 by the small-molecule RITA (reactivation of p53 and induction of tumor cell apoptosis) [2,5-bis(5-hydroxymethyl-2-thienyl) furan] (NSC-652287) inhibits HIF-1α and vascular endothelial growth factor expression in vivo and induces significant tumor cell apoptosis in normoxia and hypoxia in p53-positive cells. RITA has been proposed to stabilize p53 by inhibiting the p53-HDM2 interaction. However, induction of p53 alone was insufficient to block HIF-1α induced in hypoxia and has previously been shown to require additional stimuli, such as DNA damage. Here, we identify a new mechanism of action for RITA: RITA activates a DNA damage response, resulting in phosphorylation of p53 and γH2AX in vivo. Unlike other DNA damage response-inducing agents, RITA treatment of cells induced a p53-dependent increase in phosphorylation of the α subunit of eukaryotic initiation factor 2, requiring PKR-like endoplasmic reticulum kinase activity, and led to the subsequent downregulation of HIF-1α and p53 target proteins, including HDM2 and p21. Through the identification of a new mechanism of action for RITA, our study uncovers a novel link between the DNA damage response-p53 pathway and the protein translational machinery.

Download Full-text

Immunotherapy with Recombinant Xenogeneic Vascular Endothelial Growth Factor as a Vaccine Combined Low-Dose Adriamycin Induces Synergistic Antitumor Efficacy in EL4 Lymphoma Model.

Blood ◽

10.1182/blood.v106.11.4811.4811 ◽

2005 ◽

Vol 106 (11) ◽

pp. 4811-4811

Author(s):

Ting Niu ◽

Ting Liu ◽

Yong-qian Jia ◽

Yan-jun Wen ◽

Ling Tian ◽

...

Keyword(s):

Combination Therapy ◽

Tumor Growth ◽

Tumor Cell ◽

Cell Apoptosis ◽

Low Dose ◽

Combination Group ◽

Vascular Endothelial ◽

Tumor Cell Apoptosis ◽

Anti Vegf ◽

Endothelial Growth Factor

Abstract We explored the antitumor efficacy of a strategy using recombinant Xenopus laevis vascular endothelial growth factor (xVEGF) as a xenogeneic protein vaccine, which we have demonstrated to have effective antiangiogenic activities in several tumor models, in combination with low-dose adriamycin in lymphoma model. EL4 lymphoma model was established in C57BL/6 mice. Mice were randomly divided into four groups: combination therapy (xVEGF plus adriamycin), xVEGF treatment alone, adriamycin treatment alone, and normal saline (NS) groups, and received relevant treatments. Tumor growth, survival rate of tumor-bearing mice, and potential toxicity of regimens above were investigated. Anti-VEGF antibodies and anti-VEGF antibody-producing B cells (APBCs) were detected by Western blot analysis and enzyme-linked immunospot (ELISPOT) assay, respectively. In addition, microvessel density (MVD) within tumor tissues and tumor cell apoptosis were determined by immunohistochemistry and TUNEL staining, respectively. Our data showed that combination therapy inhibited tumor growth and improved survival of tumor-bearing mice significantly, and complete regression of tumor was observed in 3 of 10 mice in combination group in EL4 lymphoma model.Survival rate of mice was significantly higher in combination group than that in xVEGF alone group,in adriamycin alone group (P<0.05),or that in NS group (P<0.01). Remarkably, the combination treatment resulted in not only significant antiangiogenic effects but also promotion of tumor cell apoptosis. The calculated indexes of combination therapy showed synergistic relationship in terms of inhibition of tumor growth, antiangiogenesis, induction of tumor cell apoptosis. In addition, anti-VEGF antibodies and APBCs were found in mice treated with either xVEGF vaccine alone or combination treatment. No marked toxicities were found in the treated mice. In summary, these findings may provide an effective combination approach for lymphoma therapy in the future.

Download Full-text

The DNA damage inducible lncRNA SCAT7 regulates genomic integrity and topoisomerase 1 turnover in lung adenocarcinoma

NAR Cancer ◽

10.1093/narcan/zcab002 ◽

2021 ◽

Vol 3 (1) ◽

Author(s):

Luisa Statello ◽

Mohamad M Ali ◽

Silke Reischl ◽

Sagar Mahale ◽

Subazini Thankaswamy Kosalai ◽

...

Keyword(s):

Dna Damage ◽

Dna Damage Response ◽

Cancer Biology ◽

Topoisomerase I ◽

Cell Cycle Checkpoints ◽

Topoisomerase 1 ◽

Damage Response ◽

Promote Cell Survival

Abstract Despite the rapid improvements in unveiling the importance of lncRNAs in all aspects of cancer biology, there is still a void in mechanistic understanding of their role in the DNA damage response. Here we explored the potential role of the oncogenic lncRNA SCAT7 (ELF3-AS1) in the maintenance of genome integrity. We show that SCAT7 is upregulated in response to DNA-damaging drugs like cisplatin and camptothecin, where SCAT7 expression is required to promote cell survival. SCAT7 silencing leads to decreased proliferation of cisplatin-resistant cells in vitro and in vivo through interfering with cell cycle checkpoints and DNA repair molecular pathways. SCAT7 regulates ATR signaling, promoting homologous recombination. Importantly, SCAT7 also takes part in proteasome-mediated topoisomerase I (TOP1) degradation, and its depletion causes an accumulation of TOP1–cc structures responsible for the high levels of intrinsic DNA damage. Thus, our data demonstrate that SCAT7 is an important constituent of the DNA damage response pathway and serves as a potential therapeutic target for hard-to-treat drug resistant cancers.

Download Full-text

NDUFA4L2 promotes glioblastoma progression, is associated with poor survival, and can be effectively targeted by apatinib

Cell Death and Disease ◽

10.1038/s41419-021-03646-3 ◽

2021 ◽

Vol 12 (4) ◽

Author(s):

Zheng Chen ◽

Xiangyu Wei ◽

Xueyi Wang ◽

Xuan Zheng ◽

Bowen Chang ◽

...

Keyword(s):

Tumor Cell ◽

Hypoxia Inducible Factor ◽

Mitochondrial Respiratory Chain ◽

Metabolic Reprogramming ◽

Tumor Cell Apoptosis ◽

Survival Gene ◽

A Subunit ◽

Tumor Types

AbstractNADH dehydrogenase [ubiquinone] 1 alpha subcomplex, 4-like 2 (NDUFA4L2) is a subunit of Complex I of the mitochondrial respiratory chain, which is important in metabolic reprogramming and oxidative stress in multiple cancers. However, the biological role and molecular regulation of NDUFA4L2 in glioblastoma (GBM) are poorly understood. Here, we found that NDUFA4L2 was significantly upregulated in GBM; the elevated levels were correlated with reduced patient survival. Gene knockdown of NDUFA4L2 inhibited tumor cell proliferation and enhanced apoptosis, while tumor cells initiated protective mitophagy in vitro and in vivo. We used lentivirus to reduce expression levels of NDUFA4L2 protein in GBM cells exposed to mitophagy blockers, which led to a significant enhancement of tumor cell apoptosis in vitro and inhibited the development of xenografted tumors in vivo. In contrast to other tumor types, NDUFA4L2 expression in GBM may not be directly regulated by hypoxia-inducible factor (HIF)-1α, because HIF-1α inhibitors failed to inhibit NDUFA4L2 in GBM. Apatinib was able to effectively target NDUFA4L2 in GBM, presenting an alternative to the use of lentiviruses, which currently cannot be used in humans. Taken together, our data suggest the use of NDUFA4L2 as a potential therapeutic target in GBM and demonstrate a practical treatment approach.

Download Full-text

PAICS contributes to gastric carcinogenesis and participates in DNA damage response by interacting with histone deacetylase 1/2

Cell Death and Disease ◽

10.1038/s41419-020-2708-5 ◽

2020 ◽

Vol 11 (7) ◽

Author(s):

Nan Huang ◽

Chang Xu ◽

Liang Deng ◽

Xue Li ◽

Zhixuan Bian ◽

...

Keyword(s):

Dna Damage ◽

Histone Deacetylase ◽

Dna Damage Response ◽

De Novo ◽

Dna Damage Repair ◽

Histone Deacetylase 1 ◽

Damage Repair ◽

Damage Response

AbstractPhosphoribosylaminoimidazole carboxylase, phosphoribosylaminoimidazole succinocarboxamide synthetase (PAICS), an essential enzyme involved in de novo purine biosynthesis, is connected with formation of various tumors. However, the specific biological roles and related mechanisms of PAICS in gastric cancer (GC) remain unclear. In the present study, we identified for the first time that PAICS was significantly upregulated in GC and high expression of PAICS was correlated with poor prognosis of patients with GC. In addition, knockdown of PAICS significantly induced cell apoptosis, and inhibited GC cell growth both in vitro and in vivo. Mechanistic studies first found that PAICS was engaged in DNA damage response, and knockdown of PAICS in GC cell lines induced DNA damage and impaired DNA damage repair efficiency. Further explorations revealed that PAICS interacted with histone deacetylase HDAC1 and HDAC2, and PAICS deficiency decreased the expression of DAD51 and inhibited its recruitment to DNA damage sites by impairing HDAC1/2 deacetylase activity, eventually preventing DNA damage repair. Consistently, PAICS deficiency enhanced the sensitivity of GC cells to DNA damage agent, cisplatin (CDDP), both in vitro and in vivo. Altogether, our findings demonstrate that PAICS plays an oncogenic role in GC, which act as a novel diagnosis and prognostic biomarker for patients with GC.

Download Full-text

Slx4 Regulates DNA Damage Checkpoint-dependent Phosphorylation of the BRCT Domain Protein Rtt107/Esc4

Molecular Biology of the Cell ◽

10.1091/mbc.e05-08-0785 ◽

2006 ◽

Vol 17 (1) ◽

pp. 539-548 ◽

Cited By ~ 59

Author(s):

Tania M. Roberts ◽

Michael S. Kobor ◽

Suzanne A. Bastin-Shanower ◽

Miki Ii ◽

Sonja A. Horte ◽

...

Keyword(s):

Dna Damage ◽

Dna Damage Response ◽

Dna Damage Checkpoint ◽

Checkpoint Activation ◽

Alkylation Damage ◽

Binding Partner ◽

Replication Restart ◽

Damage Response ◽

Domain Protein

RTT107 (ESC4, YHR154W) encodes a BRCA1 C-terminal-domain protein that is important for recovery from DNA damage during S phase. Rtt107 is a substrate of the checkpoint protein kinase Mec1, although the mechanism by which Rtt107 is targeted by Mec1 after checkpoint activation is currently unclear. Slx4, a component of the Slx1-Slx4 structure-specific nuclease, formed a complex with Rtt107. Deletion of SLX4 conferred many of the same DNA-repair defects observed in rtt107Δ, including DNA damage sensitivity, prolonged DNA damage checkpoint activation, and increased spontaneous DNA damage. These phenotypes were not shared by the Slx4 binding partner Slx1, suggesting that the functions of the Slx4 and Slx1 proteins in the DNA damage response were not identical. Of particular interest, Slx4, but not Slx1, was required for phosphorylation of Rtt107 by Mec1 in vivo, indicating that Slx4 was a mediator of DNA damage-dependent phosphorylation of the checkpoint effector Rtt107. We propose that Slx4 has roles in the DNA damage response that are distinct from the function of Slx1-Slx4 in maintaining rDNA structure and that Slx4-dependent phosphorylation of Rtt107 by Mec1 is critical for replication restart after alkylation damage.

Download Full-text

Dephosphorylation of the C-terminal Tyrosyl Residue of the DNA Damage-related Histone H2A.X Is Mediated by the Protein Phosphatase Eyes Absent

Journal of Biological Chemistry ◽

10.1074/jbc.c900032200 ◽

2009 ◽

Vol 284 (24) ◽

pp. 16066-16070 ◽

Cited By ~ 88

Author(s):

Navasona Krishnan ◽

Dae Gwin Jeong ◽

Suk-Kyeong Jung ◽

Seong Eon Ryu ◽

Andrew Xiao ◽

...

Keyword(s):

Dna Damage ◽

Dna Damage Response ◽

Mammalian Cells ◽

Protein Tyrosine Phosphatases ◽

Histone H2a ◽

Eyes Absent ◽

Damage Repair ◽

Damage Response

In mammalian cells, the DNA damage-related histone H2A variant H2A.X is characterized by a C-terminal tyrosyl residue, Tyr-142, which is phosphorylated by an atypical kinase, WSTF. The phosphorylation status of Tyr-142 in H2A.X has been shown to be an important regulator of the DNA damage response by controlling the formation of γH2A.X foci, which are platforms for recruiting molecules involved in DNA damage repair and signaling. In this work, we present evidence to support the identification of the Eyes Absent (EYA) phosphatases, protein-tyrosine phosphatases of the haloacid dehalogenase superfamily, as being responsible for dephosphorylating the C-terminal tyrosyl residue of histone H2A.X. We demonstrate that EYA2 and EYA3 displayed specificity for Tyr-142 of H2A.X in assays in vitro. Suppression of eya3 by RNA interference resulted in elevated basal phosphorylation and inhibited DNA damage-induced dephosphorylation of Tyr-142 of H2A.X in vivo. This study provides the first indication of a physiological substrate for the EYA phosphatases and suggests a novel role for these enzymes in regulation of the DNA damage response.

Download Full-text

Inhibition of endothelial FAK activity prevents tumor metastasis by enhancing barrier function

The Journal of Cell Biology ◽

10.1083/jcb.201307067 ◽

2014 ◽

Vol 204 (2) ◽

pp. 247-263 ◽

Cited By ~ 92

Author(s):

Christine Jean ◽

Xiao Lei Chen ◽

Ju-Ock Nam ◽

Isabelle Tancioni ◽

Sean Uryu ◽

...

Keyword(s):

Tumor Growth ◽

Tumor Cell ◽

Stromal Cells ◽

Barrier Function ◽

Tumor Metastasis ◽

Vascular Endothelial ◽

Vascular Endothelial Cadherin ◽

Tumor Growth And Metastasis ◽

Endothelial Growth Factor

Pharmacological focal adhesion kinase (FAK) inhibition prevents tumor growth and metastasis, via actions on both tumor and stromal cells. In this paper, we show that vascular endothelial cadherin (VEC) tyrosine (Y) 658 is a target of FAK in tumor-associated endothelial cells (ECs). Conditional kinase-dead FAK knockin within ECs inhibited recombinant vascular endothelial growth factor (VEGF-A) and tumor-induced VEC-Y658 phosphorylation in vivo. Adherence of VEGF-expressing tumor cells to ECs triggered FAK-dependent VEC-Y658 phosphorylation. Both FAK inhibition and VEC-Y658F mutation within ECs prevented VEGF-initiated paracellular permeability and tumor cell transmigration across EC barriers. In mice, EC FAK inhibition prevented VEGF-dependent tumor cell extravasation and melanoma dermal to lung metastasis without affecting primary tumor growth. As pharmacological c-Src or FAK inhibition prevents VEGF-stimulated c-Src and FAK translocation to EC adherens junctions, but FAK inhibition does not alter c-Src activation, our experiments identify EC FAK as a key intermediate between c-Src and the regulation of EC barrier function controlling tumor metastasis.

Download Full-text