نتایج جستجو برای: k ras
تعداد نتایج: 403340 فیلتر نتایج به سال:
Background: K-ras oncogene mutations are confirmed factor for lack of clinical benefit from antibodies targeting EGFR in patients with colorectal cancer (CRC). Mutations are reported in 40% of CRC tumors in western patients. There is scarcity of data on population from Asia and the Middle East. Aims: This study investigates the frequency and impact of k-ras mutation and the association between ...
Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is rarely mutated in pancreatic cancers, but its regulation by transforming growth factor (TGF)-beta might mediate growth suppression and other oncogenic actions. Here, we examined the role of TGFbeta and the effects of oncogenic K-RAS/ERK upon PTEN expression in the absence of SMAD4. We utilized two SMAD4-null pancreatic cell lines...
Pancreatic adenocarcinoma is the fifth leading cause of cancer death in the United States. Mutations in the K-ras oncogene occur in 85% of pancreatic adenocarcinomas and have also been identified in 75% of pancreatic ducts with mucinous cell hyperplasia seen in association with chronic pancreatitis. We identified K-ras mutations in 65% of duct lesions associated not only with chronic pancreatit...
Andrographolide derivatives inhibit guanine nucleotide exchange and abrogate oncogenic Ras function.
Aberrant signaling by oncogenic mutant rat sarcoma (Ras) proteins occurs in ∼15% of all human tumors, yet direct inhibition of Ras by small molecules has remained elusive. Recently, several small-molecule ligands have been discovered that directly bind Ras and inhibit its function by interfering with exchange factor binding. However, it is unclear whether, or how, these ligands could lead to dr...
Enhanced signaling by the small guanosine triphosphatase Ras is common in T cell acute lymphoblastic leukemia/lymphoma (T-ALL), but the underlying mechanisms are unclear. We identified the guanine nucleotide exchange factor RasGRP1 (Rasgrp1 in mice) as a Ras activator that contributes to leukemogenesis. We found increased RasGRP1 expression in many pediatric T-ALL patients, which is not observe...
The Ras proto-oncogene mediates a wide variety of cellular events and is frequently mutated in cancer. MicroRNAs (miRNAs) may regulate the development of cancer through their effect on the target genes. In the search of miRNAs that target on Ras, miR-18a* is the first time confirmed to target on K-Ras and furthermore not on N- and H-Ras. miR-18a* repression by transfection with anti-miR-18a* in...
Ras functions as a molecular switch for several downstream targets and may promote either apoptosis or survival dependent upon the cell system and stimulus. The functional significance of a transfected K-Ras oncogene in influencing apoptosis induced by thymineless stress was examined in a thymidylate synthase (TS)-deficient (TS-) colon carcinoma cell line derived from GC3/c1 after thymidine dep...
A high frequency of K-ras mutations may indicate preneoplastic changes in the bronchial epithelium as a result of genotoxic injury. With the use of sensitive detection techniques, we report a higher prevalence of K-ras mutations in bronchoalveolar lavage than has been reported previously for lung cancer. A PCR/ligase chain reaction technique was used to determine K-ras codon 12 mutations in a g...
Activating K-Ras mutations and inactivating mutations of Smad4 are two common genetic alterations that occur in the development and progression of pancreatic ductal adenocarcinomas (PDAC). To further study the individual and combinatorial roles of these two mutations in the pathogenesis of PDAC, immortalized human pancreas nestin postive cells (HPNE) were genetically modified by either expressi...
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