4 results on '"Agell N"'
Search Results
2. Phosphorylation at Ser-181 of oncogenic KRAS is required for tumor growth.
- Author
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Barceló C, Paco N, Morell M, Alvarez-Moya B, Bota-Rabassedas N, Jaumot M, Vilardell F, Capella G, and Agell N
- Subjects
- Animals, Cell Survival genetics, Cell Transformation, Neoplastic genetics, Cells, Cultured, Humans, Mice, Mice, Knockout, Mice, Nude, NIH 3T3 Cells, Neoplasms genetics, Neoplasms metabolism, Pancreatic Neoplasms genetics, Pancreatic Neoplasms metabolism, Pancreatic Neoplasms pathology, Phosphorylation physiology, Proto-Oncogene Proteins genetics, Proto-Oncogene Proteins p21(ras), ras Proteins genetics, Cell Proliferation, Cell Transformation, Neoplastic metabolism, Neoplasms pathology, Protein Serine-Threonine Kinases metabolism, Proto-Oncogene Proteins metabolism, Serine metabolism, ras Proteins metabolism
- Abstract
KRAS phosphorylation has been reported recently to modulate the activity of mutant KRAS protein in vitro. In this study, we defined S181 as a specific phosphorylation site required to license the oncogenic function of mutant KRAS in vivo. The phosphomutant S181A failed to induce tumors in mice, whereas the phosphomimetic mutant S181D exhibited an enhanced tumor formation capacity, compared with the wild-type KRAS protein. Reduced growth of tumors composed of cells expressing the nonphosphorylatable KRAS S181A mutant was correlated with increased apoptosis. Conversely, increased growth of tumors composed of cells expressing the phosphomimetic KRAS S181D mutant was correlated with increased activation of AKT and ERK, two major downstream effectors of KRAS. Pharmacologic treatment with PKC inhibitors impaired tumor growth associated with reduced levels of phosphorylated KRAS and reduced effector activation. In a panel of human tumor cell lines expressing various KRAS isoforms, we showed that KRAS phosphorylation was essential for survival and tumorigenic activity. Furthermore, we identified phosphorylated KRAS in a panel of primary human pancreatic tumors. Taken together, our findings establish that KRAS requires S181 phosphorylation to manifest its oncogenic properties, implying that its inhibition represents a relevant target to attack KRAS-driven tumors., (©2013 AACR.)
- Published
- 2014
- Full Text
- View/download PDF
3. Chk1- and claspin-dependent but ATR/ATM- and Rad17-independent DNA replication checkpoint response in HeLa cells.
- Author
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Rodríguez-Bravo V, Guaita-Esteruelas S, Florensa R, Bachs O, and Agell N
- Subjects
- Ataxia Telangiectasia Mutated Proteins, Caffeine pharmacology, Cell Cycle drug effects, Checkpoint Kinase 1, Colony-Forming Units Assay, Cyclin B physiology, Cyclin B1, Gene Expression Regulation, Neoplastic, HeLa Cells, Humans, Hydroxyurea pharmacology, RNA, Small Interfering genetics, Xenopus Proteins, Adaptor Proteins, Signal Transducing genetics, Cell Cycle Proteins genetics, DNA Repair, DNA Replication drug effects, DNA-Binding Proteins genetics, Protein Kinases physiology, Protein Serine-Threonine Kinases genetics, Tumor Suppressor Proteins genetics
- Abstract
When DNA synthesis is inhibited, DNA replication checkpoint is activated to prevent mitosis entry without fully replicated DNA. In Xenopus, caffeine-sensitive kinases [ataxia telangiectasia mutated (ATM) and ATM-related protein (ATR)] are essential in this checkpoint response, but in mammal cells an ATR/ATM-independent checkpoint response to DNA synthesis inhibition exists. Using HeLa cells, which have a caffeine-insensitive checkpoint response, we have analyzed here which molecules known to be involved in the DNA replication checkpoint participate in the caffeine-insensitive response. When DNA synthesis was inhibited in the presence of UCN01 or after knocking down Chk1 expression [Chk1 small interfering RNA (siRNA)], HeLa cells entered into aberrant mitosis. Consequently, Chk1 is essential for both the ATR/ATM-dependent and ATR/ATM-independent checkpoint response in HeLa cells. Neither wortmannin, Ly294002, nor SB202190 abrogated the caffeine-insensitive checkpoint response, indicating that DNA-PK and p38 alpha,beta are not involved in the ATR/ATM-independent Chk1 activation upon DNA synthesis inhibition. Using siRNA to knock down Rad17 and claspin, two molecules involved in sensing stalled replication forks, we also showed that claspin but not Rad17 is essential for the ATR/ATM-independent checkpoint response. Inhibition of DNA synthesis in HeLa cells led to a decrease in cyclin B1 protein accumulation that was abrogated when UCN01 was added or when claspin was knocked down. We conclude that upon DNA synthesis inhibition, Chk1 can be activated in a claspin-dependent manner independently of ATR and ATM, leading to cyclin B1 down-regulation and providing the cells of an additional mechanism to inhibit mitosis entry.
- Published
- 2006
- Full Text
- View/download PDF
4. Nuclear protein patterns in normal T-lymphocytes and lymphoblastoid cells.
- Author
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Estañol JM, Agell N, and Bachs O
- Subjects
- Antigens, Nuclear, Cell Division, Cell Line, Humans, Lymphocytes cytology, T-Lymphocytes chemistry, T-Lymphocytes cytology, Lymphocytes chemistry, Nuclear Proteins analysis
- Abstract
We compared the two-dimensional patterns of nuclear proteins obtained from normal quiescent T lymphocytes with those from normal proliferating T lymphocytes and three lymphoblastoid cell lines (CEM, Namalwa, and Molt-4). We identified sets of nuclear proteins which are specific for normal quiescent or normal proliferating T lymphocytes, or shared by the three lymphoblastoid cell lines and absent from the normal T cells. The protein patterns from two nuclear subfractions, i.e., S1 fraction, obtained after nuclease extraction, and the nuclear matrix, were also analyzed. In S1 nuclear fraction, 6 proteins of 75 kDa [isoelectric point (pI) 4.4], 55 kDa (pI 6.7), 41 kDa (pI 4.1), 39 kDa (pI 5.0), 32 kDa (pI 5.5), and 29 kDa (pI 6.6) were found to be specifically present in normal quiescent cells but not in normal proliferating or lymphoblastoid cell lines. Five proteins of 23 kDa (pI 4.2), 23 kDa (pI 4.3), 22 kDa (pI 4.4), 21 kDa (pI 4.5), and 21 kDa (pI 4.6) were observed only in the S1 fraction of normal proliferating lymphocytes, whereas they were absent in normal quiescent cells and in the transformed cell lines. Eight proteins of 56 kDa (pI 4.7), 50 kDa (pI 4.6), 45 kDa (pI 4.4), 43 kDa (pI 4.3), 42 kDa (pI 4.3), 41 kDa (pI 4.3), 43 kDa (pI 4.2), and 42 kDa (pI 4.1) were found only in the nuclear matrix of normal quiescent cells. Moreover, two doublets of proteins of 31-33 kDa (pI 4.3) and 31-33 kDa (pI 4.2) were found only in the nuclear matrix of the normal proliferating cells and three proteins of 37 kDa (pI 3.8), 37 kDa (pI 3.7), and 35 kDa (pI 4.5) were specifically present in the nuclear matrix of the lymphoblastoid cells lines, but not in normal quiescent or activated lymphocytes.
- Published
- 1997
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