TY - JOUR
T1 - PP2A inhibition is a druggable MEK inhibitor resistance mechanism in KRAS-mutant lung cancer cells
AU - Kauko, Otto
AU - O’Connor, Caitlin M.
AU - Kulesskiy, Evgeny
AU - Sangodkar, Jaya
AU - Aakula, Anna
AU - Izadmehr, Sudeh
AU - Yetukuri, Laxman
AU - Yadav, Bhagwan
AU - Padzik, Artur
AU - Laajala, Teemu Daniel
AU - Haapaniemi, Pekka
AU - Momeny, Majid
AU - Varila, Taru
AU - Ohlmeyer, Michael
AU - Aittokallio, Tero
AU - Wennerberg, Krister
AU - Narla, Goutham
AU - Westermarck, Jukka
PY - 2018/7/18
Y1 - 2018/7/18
N2 - Kinase inhibitor resistance constitutes a major unresolved clinical challenge in cancer. Furthermore, the role of serine/threonine phosphatase deregulation as a potential cause for resistance to kinase inhibitors has not been thoroughly addressed. We characterize protein phosphatase 2A (PP2A) activity as a global determinant of KRAS-mutant lung cancer cell resistance across a library of >200 kinase inhibitors. The results show that PP2A activity modulation alters cancer cell sensitivities to a large number of kinase inhibitors. Specifically, PP2A inhibition ablated mitogen-activated protein kinase kinase (MEK) inhibitor response through the collateral activation of AKT/mammalian target of rapamycin (mTOR) signaling. Combination of mTOR and MEK inhibitors induced cytotoxicity in PP2A-inhibited cells, but even this drug combination could not abrogate MYC up-regulation in PP2A-inhibited cells. Treatment with an orally bioavailable small-molecule activator of PP2A DT-061, in combination with the MEK inhibitor AZD6244, resulted in suppression of both p-AKT and MYC, as well as tumor regression in two KRAS-driven lung cancer mouse models. DT-061 therapy also abrogated MYC-driven tumorigenesis. These data demonstrate that PP2A deregulation drives MEK inhibitor resistance in KRAS-mutant cells. These results emphasize the need for better understanding of phosphatases as key modulators of cancer therapy responses.
AB - Kinase inhibitor resistance constitutes a major unresolved clinical challenge in cancer. Furthermore, the role of serine/threonine phosphatase deregulation as a potential cause for resistance to kinase inhibitors has not been thoroughly addressed. We characterize protein phosphatase 2A (PP2A) activity as a global determinant of KRAS-mutant lung cancer cell resistance across a library of >200 kinase inhibitors. The results show that PP2A activity modulation alters cancer cell sensitivities to a large number of kinase inhibitors. Specifically, PP2A inhibition ablated mitogen-activated protein kinase kinase (MEK) inhibitor response through the collateral activation of AKT/mammalian target of rapamycin (mTOR) signaling. Combination of mTOR and MEK inhibitors induced cytotoxicity in PP2A-inhibited cells, but even this drug combination could not abrogate MYC up-regulation in PP2A-inhibited cells. Treatment with an orally bioavailable small-molecule activator of PP2A DT-061, in combination with the MEK inhibitor AZD6244, resulted in suppression of both p-AKT and MYC, as well as tumor regression in two KRAS-driven lung cancer mouse models. DT-061 therapy also abrogated MYC-driven tumorigenesis. These data demonstrate that PP2A deregulation drives MEK inhibitor resistance in KRAS-mutant cells. These results emphasize the need for better understanding of phosphatases as key modulators of cancer therapy responses.
U2 - 10.1126/scitranslmed.aaq1093
DO - 10.1126/scitranslmed.aaq1093
M3 - Journal article
C2 - 30021885
AN - SCOPUS:85050393072
SN - 1946-6234
VL - 10
SP - 1
EP - 12
JO - Science Translational Medicine
JF - Science Translational Medicine
IS - 450
M1 - eaaq1093
ER -