Browse
Submit Data
Databases
API
Help

Dataset Information

9 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

The influence of AKT isoforms on radiation sensitivity and DNA repair in colon cancer cell lines.

ABSTRACT: In response to ionizing radiation, several signaling cascades in the cell are activated to repair the DNA breaks, prevent apoptosis, and keep the cells proliferating. AKT is important for survival and proliferation and may also be an activating factor for DNA-PKcs and MRE11, which are essential proteins in the DNA repair process. AKT (PKB) is hyperactivated in several cancers and is associated with resistance to radiotherapy and chemotherapy. There are three AKT isoforms (AKT1, AKT2, and AKT3) with different expression patterns and functions in several cancer tumors. The role of AKT isoforms has been investigated in relation to radiation response and their effects on DNA repair proteins (DNA-PKcs and MRE11) in colon cancer cell lines. The knockout of AKT1 and/or AKT2 affected the radiation sensitivity, and a deficiency of both isoforms impaired the rejoining of radiation-induced DNA double strand breaks. Importantly, the active/phosphorylated forms of AKT and DNA-PKcs associate and exposure to ionizing radiation causes an increase in this interaction. Moreover, an increased expression of both DNA-PKcs and MRE11 was observed when AKT expression was ablated, yet only DNA-PKcs expression influenced AKT phosphorylation. Taken together, these results demonstrate a role for both AKT1 and AKT2 in radiotherapy response in colon cancer cells involving DNA repair capacity through the nonhomologous end joining pathway, thus suggesting that AKT in combination with DNA-PKcs inhibition may be used for radiotherapy sensitizing strategies in colon cancer.

SUBMITTER: Sahlberg SH

PROVIDER: S-EPMC3980041 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Clinical radiation sensitivity with DNA repair disorders: an overview.

Project description:Adverse reactions to radiotherapy represent a confounding phenomenon in radiation oncology. These reactions are rare, and many have been associated with individuals with DNA repair disorders such as ataxia-telangiectasia and Nijmegen Breakage syndrome. A paucity of published data is available detailing such circumstances. This overview describes four exemplary situations, a comprehensive list of 32 additional cases, and some insights gleaned from this overall experience. Fanconi anemia was associated with more than one-half of the reports. The lowest dose given to a patient that resulted in a reaction was 3 Gy, given to an ataxia-telangiectasia patient. Most patients died within months of exposure. It is clear that the patients discussed in this report had complicated illnesses, in addition to cancer, and the radiotherapy administered was most likely their best option. However, the underlying DNA repair defects make conventional radiation doses dangerous. Our findings support previous wisdom that radiotherapy should either be avoided or the doses should be selected with great care in the case of these radiosensitive genotypes, which must be recognized by their characteristic phenotypes, until more rapid, reliable, and functional assays of DNA repair become available.

| S-EPMC2725446 | biostudies-literature

Evaluation of cancer stem cell markers CD133, CD44, CD24: association with AKT isoforms and radiation resistance in colon cancer cells.

Project description:The cell surface proteins CD133, CD24 and CD44 are putative markers for cancer stem cell populations in colon cancer, associated with aggressive cancer types and poor prognosis. It is important to understand how these markers may predict treatment outcomes, determined by factors such as radioresistance. The scope of this study was to assess the connection between EGFR, CD133, CD24, and CD44 (including isoforms) expression levels and radiation sensitivity, and furthermore analyze the influence of AKT isoforms on the expression patterns of these markers, to better understand the underlying molecular mechanisms in the cell. Three colon cancer cell-lines were used, HT-29, DLD-1, and HCT116, together with DLD-1 isogenic AKT knock-out cell-lines. All three cell-lines (HT-29, HCT116 and DLD-1) expressed varying amounts of CD133, CD24 and CD44 and the top ten percent of CD133 and CD44 expressing cells (CD133high/CD44high) were more resistant to gamma radiation than the ten percent with lowest expression (CD133low/CD44low). The AKT expression was lower in the fraction of cells with low CD133/CD44. Depletion of AKT1 or AKT2 using knock out cells showed for the first time that CD133 expression was associated with AKT1 but not AKT2, whereas the CD44 expression was influenced by the presence of either AKT1 or AKT2. There were several genes in the cell adhesion pathway which had significantly higher expression in the AKT2 KO cell-line compared to the AKT1 KO cell-line; however important genes in the epithelial to mesenchymal transition pathway (CDH1, VIM, TWIST1, SNAI1, SNAI2, ZEB1, ZEB2, FN1, FOXC2 and CDH2) did not differ. Our results demonstrate that CD133high/CD44high expressing colon cancer cells are associated with AKT and increased radiation resistance, and that different AKT isoforms have varying effects on the expression of cancer stem cell markers, which is an important consideration when targeting AKT in a clinical setting.

| S-EPMC3997403 | biostudies-literature

Sphingosine kinase isoforms regulate oxaliplatin sensitivity of human colon cancer cells through ceramide accumulation and Akt activation.

Project description:The relationship between sphingosine kinase (SPHK), cellular ceramide concentration and chemosensitivity was investigated in human colon cancer cell lines. Among nine colon cancer cell lines, SPHK1 and SPHK2 activity and protein expression was highest in RKO cells and lowest in HCT116 cells. A viability assay revealed that HCT116 cells were sensitive to the effects of oxaliplatin (l-OHP), whereas RKO cells were resistant to those of l-OHP. Treatment with 5microg/ml l-OHP induced a marked time-dependent increase in various ceramides (C16, C24, C24:1) in HCT116 cells but not in RKO cells, as indicated by liquid chromatography/mass spectrometry. The increase in ceramide and caspase activation induced by l-OHP in the sensitive HCT116 cells was abolished by pretreatment with a neutral sphingomyelinase inhibitor, suggesting that the ceramide formation was due to the activation of neutral, rather than acid, sphingomyelinase. In contrast, in l-OHP-resistant RKO cells, treatment with an SPHK inhibitor or SPHK1 and SPHK2 silencing by RNA interference suppressed cell viability and increased caspase activity and cellular ceramide formation after l-OHP treatment. The elevated ceramide formation induced by SPHK inhibition and l-OHP was inhibited by fumonisin B1 but not myriocin, suggesting that ceramide formation was through the salvage pathway. Endogenous phosphorylated Akt levels were much higher in the resistant RKO cells than in the sensitive HCT116 cells. Either SPHK1 or SPHK2 silencing in RKO cells decreased phosphorylated Akt levels and increased p53 and p21 protein levels as well as poly(ADP-ribose) polymerase cleavage in response to l-OHP treatment. These findings indicate that SPHK isoforms and neutral sphingomyelinase contribute to the regulation of chemosensitivity by controlling ceramide formation and the downstream Akt pathway in human colon cancer cells.

| S-EPMC2667729 | biostudies-literature

Dual Targeting of Akt and mTORC1 Impairs Repair of DNA Double-Strand Breaks and Increases Radiation Sensitivity of Human Tumor Cells.

Project description:Inhibition of mammalian target of rapamycin-complex 1 (mTORC1) induces activation of Akt. Because Akt activity mediates the repair of ionizing radiation-induced DNA double-strand breaks (DNA-DSBs) and consequently the radioresistance of solid tumors, we investigated whether dual targeting of mTORC1 and Akt impairs DNA-DSB repair and induces radiosensitization. Combining mTORC1 inhibitor rapamycin with ionizing radiation in human non-small cell lung cancer (NSCLC) cells (H661, H460, SK-MES-1, HTB-182, A549) and in the breast cancer cell line MDA-MB-231 resulted in radiosensitization of H661 and H460 cells (responders), whereas only a very slight effect was observed in A549 cells, and no effect was observed in SK-MES-1, HTB-182 or MDA-MB-231 cells (non-responders). In responder cells, rapamycin treatment did not activate Akt1 phosphorylation, whereas in non-responders, rapamycin mediated PI3K-dependent Akt activity. Molecular targeting of Akt by Akt inhibitor MK2206 or knockdown of Akt1 led to a rapamycin-induced radiosensitization of non-responder cells. Compared to the single targeting of Akt, the dual targeting of mTORC1 and Akt1 markedly enhanced the frequency of residual DNA-DSBs by inhibiting the non-homologous end joining repair pathway and increased radiation sensitivity. Together, lack of radiosensitization induced by rapamycin was associated with rapamycin-mediated Akt1 activation. Thus, dual targeting of mTORC1 and Akt1 inhibits repair of DNA-DSB leading to radiosensitization of solid tumor cells.

| S-EPMC4854483 | biostudies-literature

An RNAi screen in human cell lines reveals conserved DNA damage repair pathways that mitigate formaldehyde sensitivity.

Project description:Formaldehyde is a ubiquitous DNA damaging agent, with human exposures occurring from both exogenous and endogenous sources. Formaldehyde exposure can result in multiple types of DNA damage, including DNA-protein crosslinks and thus, is representative of other exposures that induce DNA-protein crosslinks such as cigarette smoke, automobile exhaust, wood smoke, metals, ionizing radiation, and certain chemotherapeutics. Our objective in this study was to identify the genes necessary to mitigate formaldehyde toxicity following chronic exposure in human cells. We used siRNAs that targeted 320 genes representing all major human DNA repair and damage response pathways, in order to assess cell proliferation following siRNA depletion and subsequent formaldehyde treatment. Three unrelated human cell lines frequently used in genotoxicity studies (SW480, U-2 OS and GM00639) were used to identify common pathways involved in mitigating formaldehyde sensitivity. Although there were gene-specific differences among the cell lines, four inter-related cellular pathways were determined to mitigate formaldehyde toxicity: homologous recombination, DNA double-strand break repair, ionizing radiation response and DNA replication. Additional insight into cell line-specific response patterns was obtained by using a combination of exome sequencing and Cancer Cell Line Encyclopedia genomic data. The results of this DNA damage repair pathway-focused siRNA screen for formaldehyde toxicity in human cells provide a foundation for detailed mechanistic analyses of pathway-specific involvement in the response to environmentally-induced DNA-protein crosslinks and, more broadly, genotoxicity studies using human and other mammalian cell lines.

| S-EPMC6652219 | biostudies-literature

Differential activation of JNK1 isoforms by TRAIL receptors modulate apoptosis of colon cancer cell lines.

Project description:Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis on binding to its receptors, death receptor 4 and 5 (DR4, DR5). TRAIL can also activate c-Jun N-terminal kinase (JNK) through the adaptor molecules, TNF receptor-associated factor 2 (TRAF2) and receptor-interacting protein (RIP). The role of JNK in TRAIL-induced tumour cell apoptosis is unclear. In this study, we demonstrate that JNK is activated by TRAIL in colon cancer cells. Inhibition of JNK with L-JNKI reduced rhTRAIL-induced cell death but enhanced cell death induced by selective activation of DR4 or DR5. This difference was unrelated to receptor internalisation or differential activation of c-Jun, but activation of different JNK isoforms. Our data demonstrate that JNK1, but not JNK2 is activated by rhTRAIL in the examined colon cancer cell lines. Although rhTRAIL activated both the long and short isoforms of JNK1, selective activation of DR4 or DR5 led to predominant activation of the short JNK1 isoforms (JNK1alpha1 and/or JNK1beta1). Knockdown of JNK1alpha1 by shRNA enhanced apoptosis induced by TRAIL, agonistic DR4 or DR5 antibodies. On the other hand, knockdown of the long JNK1 isoforms (JNK1alpha2 and JNK1beta2) had the opposite effect; it reduced TRAIL-induced cell death. These data indicate that the short JNK1 isoforms transmit an antiapoptotic signal, whereas the long isoforms (JNK1alpha2 or JNK1beta2) act in a proapoptotic manner.

| S-EPMC2694422 | biostudies-literature

Sensitivity to inhibition of DNA repair by Olaparib in novel oropharyngeal cancer cell lines infected with Human Papillomavirus.

Project description:The incidence of Human Papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC) is increasing rapidly in the UK. Patients with HPV-positive OPSCC generally show superior clinical responses relative to HPV-negative patients. We hypothesised that these superior responses could be associated with defective repair of DNA double strand breaks (DSB). The study aimed to determine whether defective DNA repair could be associated with sensitivity to inhibition of DNA repair using the PARP inhibitor Olaparib. Sensitivity to Olaparib, and induction and repair of DNA damage, were assessed in a panel of 8 OPSCC cell-lines, including 2 novel HPV-positive lines. Effects on cell cycle distribution and levels of PARP1 and p53 were quantified. RNA-sequencing was used to assess differences in activity of DNA repair pathways. Two HPV-positive OPSCC lines were sensitive to Olaparib at potentially therapeutic doses (0.1-0.5 μM). Two HPV-negative lines were sensitive at an intermediate dose. Four other lines, derived from HPV-positive and HPV-negative tumours, were resistant to PARP inhibition. Only one cell-line, UPCISCC90, showed results consistent with the original hypothesis i.e. that in HPV-positive cells, treatment with Olaparib would cause accumulation of DSB, resulting in cell cycle arrest. There was no evidence that HPV-positive tumours exhibit defective repair of DSB. However, the data suggest that a subset of OPSCC may be susceptible to PARP-inhibitor based therapy.

| S-EPMC6292594 | biostudies-literature

Nonlinear quantitative radiation sensitivity prediction model based on NCI-60 cancer cell lines.

Project description:We proposed a nonlinear model to perform a novel quantitative radiation sensitivity prediction. We used the NCI-60 panel, which consists of nine different cancer types, as the platform to train our model. Important radiation therapy (RT) related genes were selected by significance analysis of microarrays (SAM). Orthogonal latent variables (LVs) were then extracted by the partial least squares (PLS) method as the new compressive input variables. Finally, support vector machine (SVM) regression model was trained with these LVs to predict the SF2 (the surviving fraction of cells after a radiation dose of 2 Gy γ-ray) values of the cell lines. Comparison with the published results showed significant improvement of the new method in various ways: (a) reducing the root mean square error (RMSE) of the radiation sensitivity prediction model from 0.20 to 0.011; and (b) improving prediction accuracy from 62% to 91%. To test the predictive performance of the gene signature, three different types of cancer patient datasets were used. Survival analysis across these different types of cancer patients strongly confirmed the clinical potential utility of the signature genes as a general prognosis platform. The gene regulatory network analysis identified six hub genes that are involved in canonical cancer pathways.

| S-EPMC4083270 | biostudies-literature

Inhibition of Nuclear PTEN Tyrosine Phosphorylation Enhances Glioma Radiation Sensitivity through Attenuated DNA Repair.

Project description: Not available

| S-EPMC8717880 | biostudies-literature

Inhibition of Nuclear PTEN Tyrosine Phosphorylation Enhances Glioma Radiation Sensitivity through Attenuated DNA Repair.

Project description:Ionizing radiation (IR) and chemotherapy are standard-of-care treatments for glioblastoma (GBM) patients and both result in DNA damage, however, the clinical efficacy is limited due to therapeutic resistance. We identified a mechanism of such resistance mediated by phosphorylation of PTEN on tyrosine 240 (pY240-PTEN) by FGFR2. pY240-PTEN is rapidly elevated and bound to chromatin through interaction with Ki-67 in response to IR treatment and facilitates the recruitment of RAD51 to promote DNA repair. Blocking Y240 phosphorylation confers radiation sensitivity to tumors and extends survival in GBM preclinical models. Y240F-Pten knockin mice showed radiation sensitivity. These results suggest that FGFR-mediated pY240-PTEN is a key mechanism of radiation resistance and is an actionable target for improving radiotherapy efficacy.

| S-EPMC6424615 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data