scholarly journals A20/TNFAIP3 Regulates the DNA Damage Response and Mediates Tumor Cell Resistance to DNA-Damaging Therapy

2017 ◽  
Vol 78 (4) ◽  
pp. 1069-1082 ◽  
Author(s):  
Chuanzhen Yang ◽  
Weicheng Zang ◽  
Zefang Tang ◽  
Yapeng Ji ◽  
Ruidan Xu ◽  
...  
Keyword(s):  
Dna Damage ◽  
Tumor Cell ◽  
Dna Damage Response ◽  
Cell Resistance ◽  
Damage Response ◽  
Tumor Cell Resistance

scholarly journals VRK1 Depletion Facilitates the Synthetic Lethality of Temozolomide and Olaparib in Glioblastoma Cells

2021 ◽  
Vol 9 ◽  
Author(s):  
Elena Navarro-Carrasco ◽  
Pedro A. Lazo
Keyword(s):  
Dna Damage ◽  
Cell Death ◽  
Tumor Cell ◽  
Dna Damage Response ◽  
Synthetic Lethality ◽  
Glioblastoma Cell ◽  
Glioblastoma Cells ◽  
Tumor Cell Death ◽  
Damage Response ◽  
Parp 1

BackgroundGlioblastomas treated with temozolomide frequently develop resistance to pharmacological treatments. Therefore, there is a need to find alternative drug targets to reduce treatment resistance based on tumor dependencies. A possibility is to target simultaneously two proteins from different DNA-damage repair pathways to facilitate tumor cell death. Therefore, we tested whether targeting the human chromatin kinase VRK1 by RNA interference can identify this protein as a novel molecular target to reduce the dependence on temozolomide in combination with olaparib, based on synthetic lethality.Materials and MethodsDepletion of VRK1, an enzyme that regulates chromatin dynamic reorganization and facilitates resistance to DNA damage, was performed in glioblastoma cells treated with temozolomide, an alkylating agent used for GBM treatment; and olaparib, an inhibitor of PARP-1, used as sensitizer. Two genetically different human glioblastoma cell lines, LN-18 and LN-229, were used for these experiments. The effect on the DNA-damage response was followed by determination of sequential steps in this process: H4K16ac, γH2AX, H4K20me2, and 53BP1.ResultsThe combination of temozolomide and olaparib increased DNA damage detected by labeling free DNA ends, and chromatin relaxation detected by H4K16ac. The combination of both drugs, at lower doses, resulted in an increase in the DNA damage response detected by the formation of γH2AX and 53BP1 foci. VRK1 depletion did not prevent the generation of DNA damage in TUNEL assays, but significantly impaired the DNA damage response induced by temozolomide and olaparib, and mediated by γH2AX, H4K20me2, and 53BP1. The combination of these drugs in VRK1 depleted cells resulted in an increase of glioblastoma cell death detected by annexin V and the processing of PARP-1 and caspase-3.ConclusionDepletion of the chromatin kinase VRK1 promotes tumor cell death at lower doses of a combination of temozolomide and olaparib treatments, and can be a novel alternative target for therapies based on synthetic lethality.

scholarly journals Senescence Induction by Combined Ionizing Radiation and DNA Damage Response Inhibitors in Head and Neck Squamous Cell Carcinoma Cells

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 2012 ◽  
Author(s):  
Clara Dobler ◽  
Tina Jost ◽  
Markus Hecht ◽  
Rainer Fietkau ◽  
Luitpold Distel
Keyword(s):  
Dna Damage ◽  
Squamous Cell Carcinoma ◽  
Ionizing Radiation ◽  
Tumor Cell ◽  
Cell Lines ◽  
Dna Damage Response ◽  
Ataxia Telangiectasia ◽  
Fibroblast Cell ◽  
Hpv Status ◽  
Damage Response

DNA damage response inhibitors (DDRi) may selectively enhance the inactivation of tumor cells in combination with ionizing radiation (IR). The induction of senescence may be the key mechanism of tumor cell inactivation in this combinatorial treatment. In the current study the effect of combined IR with DDRi on the induction of senescence was studied in head and neck squamous cell carcinoma (HNSCC) cells with different human papilloma virus (HPV) status. The integrity of homologous recombination (HR) was assessed in two HPV positive, two HPV negative HNSCC, and two healthy fibroblast cell cultures. Cells were treated with the DDRi CC-115 (DNA-dependent protein kinase, DNA-pK; dual mammalian target of rapamycin, mTor), VE-822 (ATR; ataxia telangiectasia and Rad3-related kinase), and AZD0156 (ATM; ataxia telangiectasia mutated kinase) combined with IR. Effects on senescence, apoptosis, necrosis, and cell cycle were analyzed by flow cytometry. The fibroblast cell lines generally tolerated IR or combined treatment better than the tumor cell lines. The ATM and ATR inhibitors were effectively inducing senescence when combined with IR. The DNA-PK inhibitor was not an important inductor of senescence. HPV status and HR activity had a limited influence on the efficacy of DDRi. Induction of senescence and necrosis varied individually among the cell lines due to molecular heterogeneity and the involvement of DNA damage response pathways in senescence induction.

scholarly journals Cancer Stem Cells from Tumor Cell Lines Activate the DNA Damage Response Pathway after Ionizing Radiation More Efficiently Than Noncancer Stem Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Heriberto Abraham Valencia-González ◽  
Graciela Ruíz ◽  
Elizabeth Ortiz-Sánchez ◽  
Alejandro García-Carrancá
Keyword(s):  
Stem Cells ◽  
Dna Damage ◽  
Cancer Stem Cells ◽  
Tumor Cell ◽  
Tumor Cells ◽  
Dna Damage Response ◽  
Tumor Cell Line ◽  
Damage Response ◽  
Sensor Proteins ◽  
Dna Damage Response Pathway

Recently, a subpopulation of tumor cells, called cancer stem cells (CSC), has been characterized, and these have emerged as a major topic in cancer research. CSC are proposed to repair DNA damage more efficiently than the rest of tumor cells, resisting chemotherapy or radiotherapy and causing clinical recurrence and metastasis. We aimed to determine the molecular basis of radioresistance and first compared the response to ionizing radiation (IR) between cancer stem cell-enriched cultures grown as spheres and conventional tumor cell line cultures grown as monolayer, from HeLa and MCF-7 cancer cell lines. To verify that our sphere cultures were enriched in CSC, we evaluated the double staining of CD49f and ALDH activity for HeLa cells by flow cytometry. We then evaluated whether differences could exist in sensor elements in the DNA damage response pathway among these cultures. We found that CSC cultures showed less sensitivity to radiation than conventional tumor cell line cultures. We observed a higher baseline expression of activated response sensor proteins of DNA damage, such as ATM, H2A.X, and PARP1, in untreated CSC cultures. These findings provide the first evidence, to our knowledge, that DNA damage response sensor proteins are present and preferentially activated in CSC, as opposed to the bulk of cells in monolayer cultures. Likewise, they provide the basis for biological differences in response to IR between CSC and other tumor cell populations. Understanding the DNA damage response pathway may provide therapeutic targets to sensitize CSC to cytotoxic therapies to improve current cancer treatments.

scholarly journals 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

2009 ◽  
Vol 29 (8) ◽  
pp. 2243-2253 ◽  
Author(s):  
Jun Yang ◽  
Afshan Ahmed ◽  
Evon Poon ◽  
Nina Perusinghe ◽  
Alexis de Haven Brandon ◽  
...  
Keyword(s):  
Dna Damage ◽  
Tumor Cell ◽  
Dna Damage Response ◽  
Cell Apoptosis ◽  
Hypoxia Inducible Factor ◽  
Vascular Endothelial ◽  
Tumor Cell Apoptosis ◽  
Damage Response ◽  
Endothelial Growth Factor

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.

scholarly journals MBNL2 Regulates DNA Damage Response via Stabilizing p21

2021 ◽  
Vol 22 (2) ◽  
pp. 783
Author(s):  
Jin Cai ◽  
Ningchao Wang ◽  
Guanglan Lin ◽  
Haowei Zhang ◽  
Weidong Xie ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Dna Damage ◽  
Tumor Cell ◽  
Dna Damage Response ◽  
Rna Binding ◽  
Kinase Inhibitor ◽  
Rna Binding Proteins ◽  
Human Cancer ◽  
Tumor Cell Proliferation ◽  
Damage Response

RNA-binding proteins are frequently dysregulated in human cancer and able to modulate tumor cell proliferation as well as tumor metastasis through post-transcriptional regulation on target genes. Abnormal DNA damage response and repair mechanism are closely related to genome instability and cell transformation. Here, we explore the function of the RNA-binding protein muscleblind-like splicing regulator 2 (MBNL2) on tumor cell proliferation and DNA damage response. Transcriptome and gene expression analysis show that the PI3K/AKT pathway is enriched in MBNL2-depleted cells, and the expression of cyclin-dependent kinase inhibitor 1A (p21CDKN1A) is significantly affected after MBNL2 depletion. MBNL2 modulates the mRNA and protein levels of p21, which is independent of its canonical transcription factor p53. Moreover, depletion of MBNL2 increases the phosphorylation levels of checkpoint kinase 1 (Chk1) serine 345 (S345) and DNA damage response, and the effect of MBNL2 on DNA damage response is p21-dependent. MBNL2 would further alter tumor cell fate after DNA damage, MBNL2 knockdown inhibiting DNA damage repair and DNA damage-induced senescence, but promoting DNA damage-induced apoptosis.

scholarly journals HSATII RNA is induced via a noncanonical ATM-regulated DNA damage response pathway and promotes tumor cell proliferation and movement

2020 ◽  
Vol 117 (50) ◽  
pp. 31891-31901
Author(s):  
Maciej T. Nogalski ◽  
Thomas Shenk
Keyword(s):  
Breast Cancer ◽  
Cell Proliferation ◽  
Dna Damage ◽  
Tumor Cell ◽  
Dna Damage Response ◽  
Breast Cancer Cell Lines ◽  
Rna Expression ◽  
Tumor Cell Proliferation ◽  
Dna Damaging Agents ◽  
Damage Response

Pericentromeric human satellite II (HSATII) repeats are normally silent but can be actively transcribed in tumor cells, where increased HSATII copy number is associated with a poor prognosis in colon cancer, and in human cytomegalovirus (HCMV)-infected fibroblasts, where the RNA facilitates viral replication. Here, we report that HCMV infection or treatment of ARPE-19 diploid epithelial cells with DNA-damaging agents, etoposide or zeocin, induces HSATII RNA expression, and a kinase-independent function of ATM is required for the induction. Additionally, various breast cancer cell lines growing in adherent, two-dimensional cell culture express HSATII RNA at different levels, and levels are markedly increased when cells are infected with HCMV or treated with zeocin. High levels of HSATII RNA expression correlate with enhanced migration of breast cancer cells, and knockdown of HSATII RNA reduces cell migration and the rate of cell proliferation. Our investigation links high expression of HSATII RNA to the DNA damage response, centered on a noncanonical function of ATM, and demonstrates a role for the satellite RNA in tumor cell proliferation and movement.

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