Akt1 and Akt3 but not Akt2 through interaction with DNA-PKcs stimulate proliferation and post-irradiation cell survival of K-RAS-mutated cancer cells

Toulany, Mahmoud; Maier, Julia; Iida, Mari; Rebholz, Simone; Holler, Marina; Grottke, Astrid; Jüker, Manfred; Wheeler, Deric L.; Rothbauer, Ulrich; Rodemann, H. Peter

doi:10.1038/cddiscovery.2017.72

Cited by 44 publications

(43 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Next, we specifically investigated the role of Akt isoforms on YB-1 phosphorylation in MDA-MB-231 and MDA-MB-453 cells using a genetic approach. In MDA-MB-231 cells, each Akt isoform was stably knocked down with shRNA, as reported previously [ 44 ]. The Western blot and related densitometry values presented in Figure 3 C indicate that the level of P-YB-1 was not significantly affected after knockdown of any of the Akt isoforms.…”

Section: Resultsmentioning

confidence: 99%

Blocking Y-Box Binding Protein-1 through Simultaneous Targeting of PI3K and MAPK in Triple Negative Breast Cancers

Tiwari

Iida

Kosnopfel

et al. 2020

Cancers

Self Cite

View full text Add to dashboard Cite

The multifunctional protein Y-box binding protein-1 (YB-1) regulates all the so far described cancer hallmarks including cell proliferation and survival. The MAPK/ERK and PI3K/Akt pathways are also the major pathways involved in cell growth, proliferation, and survival, and are the frequently hyperactivated pathways in human cancers. A gain of function mutation in KRAS mainly leads to the constitutive activation of the MAPK pathway, while the activation of the PI3K/Akt pathway occurs either through the loss of PTEN or a gain of function mutation of the catalytic subunit alpha of PI3K (PIK3CA). In this study, we investigated the underlying signaling pathway involved in YB-1 phosphorylation at serine 102 (S102) in KRAS(G13D)-mutated triple-negative breast cancer (TNBC) MDA-MB-231 cells versus PIK3CA(H1047R)/PTEN(E307K) mutated TNBC MDA-MB-453 cells. Our data demonstrate that S102 phosphorylation of YB-1 in KRAS-mutated cells is mainly dependent on the MAPK/ERK pathway, while in PIK3CA/PTEN-mutated cells, YB-1 S102 phosphorylation is entirely dependent on the PI3K/Akt pathway. Independent of the individual dominant pathway regulating YB-1 phosphorylation, dual targeting of MEK and PI3K efficiently inhibited YB-1 phosphorylation and blocked cell proliferation. This represents functional crosstalk between the two pathways. Our data obtained from the experiments, applying pharmacological inhibitors and genetic approaches, shows that YB-1 is a key player in cell proliferation, clonogenic activity, and tumor growth of TNBC cells through the MAPK and PI3K pathways. Therefore, dual inhibition of these two pathways or single targeting of YB-1 may be an effective strategy to treat TNBC.

show abstract

Section: Resultsmentioning

confidence: 99%

Blocking Y-Box Binding Protein-1 through Simultaneous Targeting of PI3K and MAPK in Triple Negative Breast Cancers

Tiwari

Iida

Kosnopfel

et al. 2020

Cancers

Self Cite

View full text Add to dashboard Cite

show abstract

“…In NHEJ-mediated repair of DSBs, DNA-PKcs is a crucial player, and Akt was described to be involved in activating DNA-PKcs after irradiation-induced DNA damage [12,37]. Phosphorylation of the residues T2609 and S2056 is activating DNA-PKcs, and an indicator for efficient DSB repair capacity.…”

Section: Bez235 Suppresses Nhej Due To An Impaired Phosphorylation Ofmentioning

confidence: 99%

Dual PI3K/mTOR Inhibitor NVP-BEZ235 Enhances Radiosensitivity of Head and Neck Squamous Cell Carcinoma (HNSCC) Cell Lines Due to Suppressed Double-Strand Break (DSB) Repair by Non-Homologous End Joining

Schötz

Balzer

Brandt

et al. 2020

Cancers

View full text Add to dashboard Cite

The PI3K/Akt/mTOR pathway is frequently altered in human papillomavirus (HPV)-positive and negative squamous cell carcinoma of the head and neck (HNSCC) and overstimulation is associated with poor prognosis. PI3K drives Akt activation and constitutive signaling acts pro-proliferative, supports cell survival, DNA repair, and contributes to radioresistance. Since the small molecule NVP-BEZ235 (BEZ235) is a potent dual inhibitor of this pathway, we were interested whether BEZ235 could be an efficient radiosensitizer. The 50 nM BEZ235 was found to abrogate endogenous and irradiation-induced phosphorylation of Akt (Ser473). The anti-proliferative capacity of the drug resulted in an increase in G1-phase cells. Repair of radiation-induced DNA double-strand breaks (DSBs) was strongly suppressed. Reduction in DSB repair was only apparent in G1- but not in G2-phase cells, suggesting that BEZ235 primarily affects non-homologous end joining. This finding was confirmed using a DSB repair reporter gene assay and could be attributed to an impaired phosphorylation of DNA-PKcs (S2056). Cellular radiosensitivity increased strongly after BEZ235 addition in all HNSCC cell lines used, especially when irradiated in the G0 or G1 phase. Our data indicate that targeting the PI3K/Akt/mTOR pathway by BEZ235 with concurrent radiotherapy may be considered an effective strategy for the treatment of HNSCC, regardless of the HPV and Akt status.

show abstract

“…Akt exerts an important regulatory role in the repair process of DSBs via the NHEJ pathway [12,13,15,19,20]. Likewise, our laboratory presented the first evidence for a potential involvement of Akt in HR-repair [16].…”

Section: Importance Of Akt1 and Akt2 For Hr Repair Of Dsbsmentioning

confidence: 70%

“…In fact, upregulation of Akt-signaling is a feature of various tumor entities [10]. Furthermore, PI3K/Akt signaling and especially Akt through its isoforms Akt1 and Akt3-has been shown to play a regulatory role in the DNA damage response of tumor cells through the NHEJ [12,13,15,26] and potentially HR repair mechanisms [27,28]. Toulany et al, and others [12,15,29] have demonstrated that Akt1 and Akt3 can stimulate DNA-DSB repair through NHEJ, which results in radio-resistance of non-small cell lung cancer cells.…”

Section: Discussionmentioning

confidence: 99%

“…Three isoforms of Akt exist with high homology, i.e., Akt1, Akt2, and Akt3; these Akt isoforms play important roles in cellular processes and their dysfunction is documented for a variety of human cancers [10,11]. Accumulating evidence indicates a regulatory role of Akt isoforms-especially Akt1 and Akt3 in NHEJ [12][13][14][15]. Akt1 has also been reported to be potentially involved in HR-dependent repair processes [16], however these data conflict with other reports [16][17][18].…”

Section: Introductionmentioning

confidence: 94%

See 1 more Smart Citation

Depletion of Akt1 and Akt2 Impairs the Repair of Radiation-Induced DNA Double Strand Breaks via Homologous Recombination

Gol

Rodemann

Dittmann

2019

IJMS

View full text Add to dashboard Cite

Homologous recombination repair (HRR), non-homologous end-joining (NHEJ) and alternative NHEJ are major pathways that are utilized by cells for processing DNA double strand breaks (DNA-DSBs); their function plays an important role in the radiation resistance of tumor cells. Conflicting data exist regarding the role of Akt in homologous recombination (HR), i.e., the regulation of Rad51 as a major protein of this pathway. This study was designed to investigate the specific involvement of Akt isoforms in HRR. HCT116 colon cancer cells with stable AKT-knock-out and siRNA-mediated AKT-knockdown phenotypes were used to investigate the role of Akt1 and Akt2 isoforms in HR. The results clearly demonstrated that HCT116 AKT1-KO and AKT2-KO cells have a significantly reduced Rad51 foci formation 6 h post irradiation versus parental cells. Depletion of Akt1 and Akt2 protein levels as well as inhibition of Akt kinase activity resulted in an increased number of residual-γH2AX in CENP-F positive cells mainly representing the S and G2 phase cells. Furthermore, inhibition of NHEJ and HR using DNA-PK and Rad51 antagonists resulted in stronger radiosensitivity of AKT1 and AKT2 knockout cells versus wild type cells. These data collectively show that both Akt1 and Akt2 are involved in DSBs repair through HRR.

show abstract

Akt1 and Akt3 but not Akt2 through interaction with DNA-PKcs stimulate proliferation and post-irradiation cell survival of K-RAS-mutated cancer cells

Cited by 44 publications

References 28 publications

Blocking Y-Box Binding Protein-1 through Simultaneous Targeting of PI3K and MAPK in Triple Negative Breast Cancers

Blocking Y-Box Binding Protein-1 through Simultaneous Targeting of PI3K and MAPK in Triple Negative Breast Cancers

Dual PI3K/mTOR Inhibitor NVP-BEZ235 Enhances Radiosensitivity of Head and Neck Squamous Cell Carcinoma (HNSCC) Cell Lines Due to Suppressed Double-Strand Break (DSB) Repair by Non-Homologous End Joining

Depletion of Akt1 and Akt2 Impairs the Repair of Radiation-Induced DNA Double Strand Breaks via Homologous Recombination

Contact Info

Product

Resources

About