scholarly journals Transcription Factor Eb Is Required for Macropinocytosis-Mediated Growth Recovery of Nutrient-Deprived Kras-Mutant Cells

Nutrients ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1638
Author(s):  
Seokmin Jeong ◽  
Jun-Kyu Byun ◽  
Sung Cho ◽  
Jungwook Chin ◽  
In-Kyu Lee ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Cell Growth ◽  
Cancer Cells ◽  
Human Cancer ◽  
Mutant Cell ◽  
Extracellular Proteins ◽  
Extracellular Protein ◽  
Lysosomal Degradation ◽  
Transcription Factor Eb ◽  
Mutant Cells

Macropinocytosis is a regulated form of endocytosis that mediates the nonselective uptake of nutrients to support growth under nutrient-deprived conditions. KRAS-mutant cancer cells upregulate macropinocytosis to import extracellular proteins, which subsequently undergo proteolytic degradation in the lysosome. Although transcription factor EB (TFEB) is a master regulator of lysosomal biogenesis and function, its role in the degradation of extracellular protein from macropinocytosis in KRAS-mutant cells has not previously been elucidated. In this study, we investigated the role of TFEB in the recovery of macropinocytosis-mediated mTORC1 activity and cell growth under nutrient depletion. Mouse embryonic fibroblasts (MEFs) expressing KrasG12D and KRAS-mutant human cancer cells took up markedly higher levels of tetramethylrhodamine (TMR)-dextran than the corresponding wild-type cells. siRNA-mediated inhibition of TFEB did not influence extracellular TMR-dextran uptake, but significantly attenuated lysosomal degradation of extracellular protein. Bovine serum albumin (BSA) treatment restored p-S6K levels and cell proliferation suppressed by leucine deprivation, and these effects were blocked by siTFEB. Collectively, our results show that TFEB plays a role in macropinocytosis-mediated KRAS-mutant cell growth under nutrient deprivation by promoting lysosomal degradation of extracellular proteins.

scholarly journals Transcription factor EB is involved in autophagy-mediated chemoresistance to doxorubicin in human cancer cells

2017 ◽  
Vol 38 (9) ◽  
pp. 1305-1316 ◽  
Author(s):  
Li-mei Fang ◽  
Bin Li ◽  
Jun-jie Guan ◽  
Hai-dong Xu ◽  
Gen-hai Shen ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Cancer Cells ◽  
Human Cancer ◽  
Human Cancer Cells ◽  
Transcription Factor Eb

scholarly journals Arginine Methyltransferase PRMT1 Regulates p53 Activity in Breast Cancer

Life ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 789
Author(s):  
Li-Ming Liu ◽  
Qiang Tang ◽  
Xin Hu ◽  
Jing-Jing Zhao ◽  
Yuan Zhang ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Growth ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Asymmetric Dimethylarginine ◽  
Human Cancer ◽  
Specific Inhibitor ◽  
Dependent Manner ◽  
Breast Tumorigenesis ◽  
Stress Signals

The protein p53 is one of the most important tumor suppressors, responding to a variety of stress signals. Mutations in p53 occur in about half of human cancer cases, and dysregulation of the p53 function by epigenetic modifiers and modifications is prevalent in a large proportion of the remainder. PRMT1 is the main enzyme responsible for the generation of asymmetric-dimethylarginine, whose upregulation or aberrant splicing has been observed in many types of malignancies. Here, we demonstrate that p53 function is regulated by PRMT1 in breast cancer cells. PRMT1 knockdown activated the p53 signal pathway and induced cell growth-arrest and senescence. PRMT1 could directly bind to p53 and inhibit the transcriptional activity of p53 in an enzymatically dependent manner, resulting in a decrease in the expression levels of several key downstream targets of the p53 pathway. We were able to detect p53 asymmetric-dimethylarginine signals in breast cancer cells and breast cancer tissues from patients, and the signals could be significantly weakened by silencing of PRMT1 with shRNA, or inhibiting PRMT1 activity with a specific inhibitor. Furthermore, PRMT1 inhibitors significantly impeded cell growth and promoted cellular senescence in breast cancer cells and primary tumor cells. These results indicate an important role of PRMT1 in the regulation of p53 function in breast tumorigenesis.

scholarly journals A human cancer cell line initiates DNA replication normally in the absence of ORC5 and ORC2 proteins

2020 ◽  
Vol 295 (50) ◽  
pp. 16949-16959
Author(s):  
Etsuko Shibata ◽  
Anindya Dutta
Keyword(s):  
Dna Replication ◽  
Cancer Cells ◽  
Cell Lines ◽  
Cancer Cell ◽  
Origin Recognition Complex ◽  
Human Cancer ◽  
Cancer Cell Line ◽  
Aaa Atpase ◽  
Normal Number ◽  
Mutant Cells

The origin recognition complex (ORC), composed of six subunits, ORC1–6, binds to origins of replication as a ring-shaped heterohexameric ATPase that is believed to be essential to recruit and load MCM2–7, the minichromosome maintenance protein complex, around DNA and initiate DNA replication. We previously reported the creation of viable cancer cell lines that lacked detectable ORC1 or ORC2 protein without a reduction in the number of origins firing. Here, using CRISPR-Cas9–mediated mutations, we report that human HCT116 colon cancer cells also survive when ORC5 protein expression is abolished via a mutation in the initiator ATG of the ORC5 gene. Even if an internal methionine is used to produce an undetectable, N terminally deleted ORC5, the protein would lack 80% of the AAA+ ATPase domain, including the Walker A motif. The ORC5-depleted cells show normal chromatin binding of MCM2–7 and initiate replication from a similar number of origins as WT cells. In addition, we introduced a second mutation in ORC2 in the ORC5 mutant cells, rendering both ORC5 and ORC2 proteins undetectable in the same cells and destabilizing the ORC1, ORC3, and ORC4 proteins. Yet the double mutant cells grow, recruit MCM2–7 normally to chromatin, and initiate DNA replication with normal number of origins. Thus, in these selected cancer cells, either a crippled ORC lacking ORC2 and ORC5 and present at minimal levels on the chromatin can recruit and load enough MCM2–7 to initiate DNA replication, or human cell lines can sometimes recruit MCM2–7 to origins independent of ORC.

scholarly journals Artesunate Induces Cell Death in Human Cancer Cells via Enhancing Lysosomal Function and Lysosomal Degradation of Ferritin

2014 ◽  
Vol 289 (48) ◽  
pp. 33425-33441 ◽  
Author(s):  
Nai-Di Yang ◽  
Shi-Hao Tan ◽  
Shukie Ng ◽  
Yin Shi ◽  
Jing Zhou ◽  
...  
Keyword(s):  
Cell Death ◽  
Cancer Cells ◽  
Human Cancer ◽  
Lysosomal Degradation ◽  
Lysosomal Function ◽  
Human Cancer Cells

scholarly journals A High-Throughput Screen with Isogenic PTEN+/+ and PTEN−/− Cells Identifies CID1340132 as a Novel Compound That Induces Apoptosis in PTEN and PIK3CA Mutant Human Cancer Cells

2011 ◽  
Vol 16 (4) ◽  
pp. 383-393 ◽  
Author(s):  
Hui-Fang Li ◽  
Adam Keeton ◽  
Michele Vitolo ◽  
Clinton Maddox ◽  
Lynn Rasmussen ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Cancer Cells ◽  
Tumor Suppressor Gene ◽  
High Throughput ◽  
Human Cancer ◽  
Genetic Difference ◽  
Suppressor Gene ◽  
Pten Gene ◽  
Target Cells ◽  
Mutant Cells

The PTEN tumor suppressor gene is one of the most commonly mutated genes in human cancer. Because inactivation of PTEN is a somatic event, PTEN mutations represent an important genetic difference between cancer cells and normal cells and therefore a potential anticancer drug target. However, it remains a substantial challenge to identify compounds that target loss-of-function events such as mutations of tumor suppressors. In an effort to identify small molecules that preferentially kill cells with mutations of PTEN, the authors developed and implemented a high-throughput, paired cell-based screen composed of parental HCT116 cells and their PTEN gene-targeted derivatives. From 138 758 compounds tested, two hits were identified, and one, N′-[(1-benzyl-1H-indol-3-yl)methylene]benzenesulfonohydrazide (CID1340132), was further studied using a variety of cell-based models, including HCT116, MCF10A, and HEC1A cells with targeted deletion of either their PTEN or PIK3CA genes. Preferential killing of PTEN and PIK3CA mutant cells was accompanied by DNA damage, inhibition of DNA synthesis, and apoptosis. Taken together, these data validate a cell-based screening approach for identifying lead compounds that target cells with specific tumor suppressor gene mutations and describe a novel compound with preferential killing activity toward PTEN and PIK3CA mutant cells.

Oxidative Stress Induces Binding of FANCD2 to STAT5 and Facilitates STAT5-Dependent Survival Signals.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 33-33 ◽  
Author(s):  
Grover Bagby ◽  
Winifred Keeble ◽  
Tara Koretsky ◽  
Dylan Zodrow ◽  
Richard Jove ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Ground State ◽  
Mutant Cell ◽  
Extracellular Proteins ◽  
Wild Type ◽  
Direct Role ◽  
Normal Cells ◽  
Jak2 Inhibitor ◽  
Stat Signaling ◽  
Mutant Cells

Abstract Fanconi anemia (FA) cells are hypersensitive to oxidative stress and exhibit aberrant STAT activation responses to defined extracellular proteins but whether these abnormalities are linked is unclear. Because oxidative stress is known to induce STAT activation, we hypothesized that proper STAT signaling responses in normal cells exposed to H2O2 require intact FA proteins. In fact, we found that FA-C, FA-G, and FA-D2 cells (fibroblasts) showed a significant increase in apoptosis after H2O2-exposure compared to retrovirally-complemented cells. H2O2 induced higher phospho-STAT5 (P-STAT5) expression in complemented cells than in mutant cells. Conversely, mutant cells expressed higher levels of P-STAT3 in both the ground state and after H2O2-induction than complemented cells. Aberrant STAT activation in FA mutant cells was shown to be both nucleus- and JAK2 kinase-dependent. Only low levels of STAT3 and STAT5 were induced in both mutant and complemented cytoplasts and AG490 (a Jak2 inhibitor) significantly suppressed H2O2-induced STAT5 responses. Seeking a direct role of FANCD2 in regulating proper STAT activation responses to H2O2, we carried out immunoprecipitation experiments (with an antibody to the N-terminal fragment of FANCD2) using PD20, a FA-D2 mutant cell line, and FANCD2 complemented PD20. In FANCD2-complemented and normal cells, anti-FANCD2 antibody immunoprecipitated STAT5. However, in mutant cells the same antibody immunoprecipitated STAT3, not STAT5. Thus, mutant (truncated) FANCD2 preferentially binds to and may activate STAT3 in the ground state. In fact, wild type FANCD2 also binds aberrantly to STAT3 in HSC536 (FA-C lymphoblasts) indicating that FANCC may influence the function of wild type FANCD2 and that binding of wild type FANCD2 to STAT3 does not require FANCD2 ubiquitinylation (FANCD2 is not ubiquitinylated in FA-C). Suspecting that in H2O2-exposed cells STAT5 signaling pathways lead to survival while STAT3 pathways lead to apoptosis, we transduced constitutively active mutants (*) of STATs 3 and 5 in mutant D2 and complemented cells. STAT3* increased apoptotic responses to H2O2 in complemented FA-D2 cells and STAT5* decreased apoptotic responses in H2O2-induced FA-D2 cells. In addition, the STAT5 inducible anti-apoptotic gene Bcl-XL was induced in H2O2-exposed complemented FA-D2 cells but not in FA-D2 cells. We conclude that FANCD2 functions to promote survival by ordering proper STAT signaling responses to oxidative stress and that this function of FANCD2 depends in part upon FA-C. We propose that FA cells are hypersensitive to oxidative stress in part because of imbalanced STAT signal transduction responses.

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