TY  - JOUR
A1  - Djuzenova, Cholpon S.
A1  - Fiedler, Vanessa
A1  - Memmel, Simon
A1  - Katzer, Astrid
A1  - Sisario, Dmitri
A1  - Brosch, Philippa K.
A1  - Göhrung, Alexander
A1  - Frister, Svenja
A1  - Zimmermann, Heiko
A1  - Flentje, Michael
A1  - Sukhorukov, Vladimir L.
T1  - Differential effects of the Akt inhibitor MK-2206 on migration and radiation sensitivity of glioblastoma cells
JF  - BMC Cancer
N2  - Background
Most tumor cells show aberrantly activated Akt which leads to increased cell survival and resistance to cancer radiotherapy. Therefore, targeting Akt can be a promising strategy for radiosensitization. Here, we explore the impact of the Akt inhibitor MK-2206 alone and in combination with the dual PI3K and mTOR inhibitor PI-103 on the radiation sensitivity of glioblastoma cells. In addition, we examine migration of drug-treated cells.

Methods
Using single-cell tracking and wound healing migration tests, colony-forming assay, Western blotting, flow cytometry and electrorotation we examined the effects of MK-2206 and PI-103 and/or irradiation on the migration, radiation sensitivity, expression of several marker proteins, DNA damage, cell cycle progression and the plasma membrane properties in two glioblastoma (DK-MG and SNB19) cell lines, previously shown to differ markedly in their migratory behavior and response to PI3K/mTOR inhibition.

Results
We found that MK-2206 strongly reduces the migration of DK-MG but only moderately reduces the migration of SNB19 cells. Surprisingly, MK-2206 did not cause radiosensitization, but even increased colony-forming ability after irradiation. Moreover, MK-2206 did not enhance the radiosensitizing effect of PI-103. The results appear to contradict the strong depletion of p-Akt in MK-2206-treated cells. Possible reasons for the radioresistance of MK-2206-treated cells could be unaltered or in case of SNB19 cells even increased levels of p-mTOR and p-S6, as compared to the reduced expression of these proteins in PI-103-treated samples. We also found that MK-2206 did not enhance IR-induced DNA damage, neither did it cause cell cycle distortion, nor apoptosis nor excessive autophagy.

Conclusions
Our study provides proof that MK-2206 can effectively inhibit the expression of Akt in two glioblastoma cell lines. However, due to an aberrant activation of mTOR in response to Akt inhibition in PTEN mutated cells, the therapeutic window needs to be carefully defined, or a combination of Akt and mTOR inhibitors should be considered.
KW  - DNA damage
KW  - glioblastoma multiforme
KW  - histone H2AX
KW  - irradiation
KW  - migration
KW  - mTOR
KW  - PTEN
KW  - p53
KW  - radiation sensitivity
KW  - wound healing
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-200290
VL  - 19
ER  - 
TY  - JOUR
A1  - Fischer, Thomas
A1  - Hartmann, Oliver
A1  - Reissland, Michaela
A1  - Prieto-Garcia, Cristian
A1  - Klann, Kevin
A1  - Pahor, Nikolett
A1  - Schülein-Völk, Christina
A1  - Baluapuri, Apoorva
A1  - Polat, Bülent
A1  - Abazari, Arya
A1  - Gerhard-Hartmann, Elena
A1  - Kopp, Hans-Georg
A1  - Essmann, Frank
A1  - Rosenfeldt, Mathias
A1  - Münch, Christian
A1  - Flentje, Michael
A1  - Diefenbacher, Markus E.
T1  - PTEN mutant non-small cell lung cancer require ATM to suppress pro-apoptotic signalling and evade radiotherapy
JF  - Cell & Bioscience
N2  - Background
Despite advances in treatment of patients with non-small cell lung cancer, carriers of certain genetic alterations are prone to failure. One such factor frequently mutated, is the tumor suppressor PTEN. These tumors are supposed to be more resistant to radiation, chemo- and immunotherapy.

Results
We demonstrate that loss of PTEN led to altered expression of transcriptional programs which directly regulate therapy resistance, resulting in establishment of radiation resistance. While PTEN-deficient tumor cells were not dependent on DNA-PK for IR resistance nor activated ATR during IR, they showed a significant dependence for the DNA damage kinase ATM. Pharmacologic inhibition of ATM, via KU-60019 and AZD1390 at non-toxic doses, restored and even synergized with IR in PTEN-deficient human and murine NSCLC cells as well in a multicellular organotypic ex vivo tumor model.

Conclusion
PTEN tumors are addicted to ATM to detect and repair radiation induced DNA damage. This creates an exploitable bottleneck. At least in cellulo and ex vivo we show that low concentration of ATM inhibitor is able to synergise with IR to treat PTEN-deficient tumors in genetically well-defined IR resistant lung cancer models.
KW  - PTEN
KW  - ATM
KW  - IR
KW  - NSCLC
KW  - radiotherapy
KW  - cancer
KW  - DNA-PK
KW  - PI3K
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-299865
SN  - 2045-3701
VL  - 12
ER  -