PAK1 Tyrosine Phosphorylation Is Required to Induce Epithelial–Mesenchymal Transition and Radioresistance in Lung Cancer Cells

Kim, EunGi; Youn, HyeSook; Kwon, Tai-Wan; Son, Bong Soo; Kang, JiHoon; Yang, Hee Jung; Seong, Ki Moon; Kim, Wanyeon; Youn, BuHyun

doi:10.1158/0008-5472.can-14-0735

Cited by 73 publications

(67 citation statements)

References 51 publications

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“…Transient transfection and western blot analysis were prepared as previously described [43]. For transient transfection, cells were plated at a density of 5 9 10 5 cells in 6-well dishes and incubated for 4 h. The cells were transiently transfected with the siRNA oligonucleotides targeting PP1 using DharmaFECT 1 (Dharmacon) according to the manufacturer's instruction.…”

Section: Transient Transfection and Western Blot Analysismentioning

confidence: 99%

Inflammation-induced radioresistance is mediated by ROS-dependent inactivation of protein phosphatase 1 in non-small cell lung cancer cells

et al. 2015

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Inflammation plays a pivotal role in modulating the radiation responsiveness of tumors. We determined that an inflammation response prior to irradiation contributes to radiotherapy resistance in non-small cell lung cancer (NSCLC) cells. In the clonogenic survival assay, activation of the inflammation response by lipopolysaccharide (LPS) decreased the degree of radiosensitivity in NCI-H460 cells (relatively radiosensitive cells), but had no effect in A549 cells (relatively radioresistant cells). LPS-induced radioresistance of NCI-H460 cells was also confirmed with a xenograft mouse model. The radioresistant effect observed in NCI-H460 cells was correlated with inhibition of apoptotic cell death due to reduced Caspase 3/7 activity. Moreover, we found that the levels of reactive oxygen species (ROS) were synergistically elevated in NCI-H460 cells by treatment with LPS and radiation. Increased ROS generation negatively affected the activity of protein phosphatase 1 (PP1). Decreased PP1 activity did not lead to Bad dephosphorylation, consequently resulting in the inhibition of irradiation-induced mitochondrial membrane potential loss and apoptosis. We confirmed that pre-treatment with a PP1 activator and LPS sensitized NCI-H460 cells to radiation. Taken together, our findings provided evidence that PP1 activity is critical for radiosensitization in NSCLC cells and PP1 activators can serve as promising radiosensitizers to improve therapeutic efficacy.

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Section: Transient Transfection and Western Blot Analysismentioning

confidence: 99%

Inflammation-induced radioresistance is mediated by ROS-dependent inactivation of protein phosphatase 1 in non-small cell lung cancer cells

et al. 2015

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“…We have previously proposed a Nck-dependent mechanism of this translocation [18]. PAK1 has been recently shown to get phosphorylated by JAK2 in response to irradiation of non-small cell lung cancer cells [19]. This irradiation-induced tyrosyl phosphorylation is required to activate PAK1 and maintains its stability and translocation into the nucleus [19].…”

Section: Discussionmentioning

confidence: 99%

“…We have proposed that Nck-PAK1 complex (formation of which does not depend on PAK1 kinase activity) can sequester PAK1 in cytoplasm to prevent PAK1 nuclear shuttling thereby inhibiting PAK1-dependent activation of cyclin D1 promoter [18]. Similarly to PRL treatment, irradiation of lung cancer cells also leads to phosphorylation of tyrosines 153, 201 and 285 by JAK2 resulting in increases in PAK1 stability, PAK1/Snail binding, EMT and radioresistance of lung cancer cells [19]. …”

Section: Introductionmentioning

confidence: 99%

PAK1 translocates into nucleus in response to prolactin but not to estrogen

Oladimeji

Diakonova

2016

Biochemical and Biophysical Research Communications

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Tyrosyl phosphorylation of the p21-activated serine-threonine kinase 1 (PAK1) has an essential role in regulating PAK1 functions in breast cancer cells. We previously demonstrated that PAK1 serves as a common node for estrogen (E2)- and prolactin (PRL)-dependent pathways. We hypothesize herein that intracellular localization of PAK1 is affected by PRL and E2 treatments differently. We demonstrate by immunocytochemical analysis that PAK1 nuclear translocation is ligand-dependent: only PRL but not E2 stimulated PAK1 nuclear translocation. Tyrosyl phosphorylation of PAK1 is essential for this nuclear translocation because phospho-tyrosyl-deficient PAK1 Y3F mutant is retained in the cytoplasm in response to PRL. We confirmed these data by Western blot analysis of subcellular fractions. In 30 min of PRL treatment, only 48% of pTyr-PAK1 is retained in the cytoplasm of PAK1 WT clone while 52% re-distributes into the nucleus and pTyr-PAK1 shuttles back to the cytoplasm by 60 min of PRL treatment. In contrast, PAK1 Y3F is retained in the cytoplasm. E2 treatment causes nuclear translocation of neither PAK1 WT nor PAK1 Y3F. Finally, we show by an in vitro kinase assay that PRL but not E2 stimulates PAK1 kinase activity in the nuclear fraction. Thus, PAK1 nuclear translocation is ligand-dependent: PRL activates PAK1 and induces translocation of activated pTyr-PAK1 into nucleus while E2 activates pTyr-PAK1 only in the cytoplasm.

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“…Transient transfection was performed following previous study [25]. Briefly, the mixture of Lipofectamine TM (Invitrogen, Carlsbad, CA) and pCMV6-Ltf (Origene Technologies, Rockville, MD) was incubated 30 min for formation of liposome and applied to the MIHA or HL-7702 cells for 12 hours.…”

Section: Methodsmentioning

confidence: 99%

Decreased Hepatic Lactotransferrin Induces Hepatic Steatosis in Chronic Non-Alcoholic Fatty Liver Disease Model

Lee

Son

Jeon

et al. 2018

Cell Physiol Biochem

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Background/Aims: Non-alcoholic fatty liver disease (NAFLD) is an emerging metabolic disease. Although it leads to severe hepatic diseases including steatohepatitis, cirrhosis, and hepatic cancer, little is known about therapy to prevent and cure hepatic steatosis, the first step of NAFLD. We conducted this investigation to unveil the mechanism of hepatic steatosis. Methods: We established a novel chronic NAFLD mouse model through whole body irradiation and verified the model through histological and biochemical analysis. To find molecular mechanism for hepatic steatosis, we analyzed hepatic transcriptomic profiles in this model and selected target molecule. To induce the expression of lactotransferrin (Ltf) and regulate the NAFLD, growth hormone (GH) and coumestrol was introduced to hepatocyte and mice. The universal effect of coumestrol was confirmed by administration of coumestrol to NAFLD mouse model induced by high-fructose, high-fat, and MCD diet. Results: It was observed that decreased hepatic Ltf expression led to excessive hepatic lipid accumulation in NAFLD mouse. Furthermore, we found that GH was decreased in irradiated mice and functioned as an upstream regulator of Ltf expression. It was observed that GH could stimulate Ltf expression and prevent uptake of dietary lipids in hepatocytes, leading to rescue of NAFLD. Finally, we suggested that coumestrol, a kind of isoflavonoid, could be used as an inducer of hepatic Ltf expression through cooperation with the GH signaling pathway both in vitro and in vivo. Conclusions: Hepatic Ltf prevents hepatic steatosis through inhibition of dietary lipid uptake in radiation-induced NAFLD mouse model. We also suggest coumestrol as a drug candidate for prevention of NAFLD.

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PAK1 Tyrosine Phosphorylation Is Required to Induce Epithelial–Mesenchymal Transition and Radioresistance in Lung Cancer Cells

Cited by 73 publications

References 51 publications

Inflammation-induced radioresistance is mediated by ROS-dependent inactivation of protein phosphatase 1 in non-small cell lung cancer cells

Inflammation-induced radioresistance is mediated by ROS-dependent inactivation of protein phosphatase 1 in non-small cell lung cancer cells

PAK1 translocates into nucleus in response to prolactin but not to estrogen

Decreased Hepatic Lactotransferrin Induces Hepatic Steatosis in Chronic Non-Alcoholic Fatty Liver Disease Model

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