ras genes are thought to play an important role in human cancer since they have been found to be activated frequently in several types of human tumors. From preliminary studies it has been found however, that ras mutations are extremely rare in breast tumors and therefore it was of interest to examine the frequency of such mutations. In this study we examined 65 cases of primary breast carcinom...

In melanoma, the RAS/RAF/MEK/ERK signalling pathway is an area of great interest, because it regulates tumor cell proliferation and survival. A varying mutation rate has been reported for B-RAF and N-RAS, which has been largely attributed to the differential source of tumor DNA analyzed, e.g., fixed tumor tissues or in vitro propagated melanoma cells. Notably, this variation also interfered wit...

The K-ras gene is frequently mutated in colorectal cancer and has been associated with tumor initiation and progression; approximately 90% of the activating mutations are found in codons 12 and 13 of exon 1 and just under 5% in codon 61 located in exon 2. These mutations determine single aminoacidic substitutions in the GTPase pocket leading to a block of the GTP hydrolytic activity of the K-ra...

The aims of this study were to assess the prevalence and type of activating point mutations at codons 12, 13, and 61 of the Ki-, Ha-, and N-ras genes in a series of early gastric carcinomas in white patients and to correlate these ras gene mutations, if any, with the histological type (Lauren classification), the type of growth pattern, and with the Helicobacter pylori status. Haematoxylin and ...

Previous studies have demonstrated that genes of the ras family (H, K, and N) can be activated by point mutations at codons 12, 13, and 61. In the present study we have used oligonucleotide probes corresponding to these regions to assess the role of ras gene mutations in the genesis of human rhabdomyosarcoma. To increase the sensitivity of this method the appropriate regions of the three ras ge...

Ras proteins are critical nodes in cellular signaling that integrate inputs from activated cell surface receptors and other stimuli to modulate cell fate through a complex network of effector pathways. Oncogenic RAS mutations are found in ∼25% of human cancers and are highly prevalent in hematopoietic malignancies. Because of their structural and biochemical properties, oncogenic Ras proteins a...

Activating mutations of Ras have been implicated in approximately 30% of human cancers. In every case, the biochemical consequence of such mutations is to disrupt the GTPase activity of Ras and to render Ras resistant to the actions of GTPase activating proteins. Consequently, oncogenic Ras mutants are "locked" in a GTP-bound active state. We detected a potent activity in Escherichia coli extra...

Structural alterations to proto-oncogene sequences may be involved in the pathogenesis of human thyroid neoplasms. We studied 128 thyroid tumours (35 benign and 93 malignant) for ras gene point mutations in three different codons (12, 13 and 61) using a restriction fragment length polymorphism technique and direct sequencing of double-stranded DNA on polymerase chain-reaction-amplified tumour D...

BACKGROUND In advanced colorectal cancer, K-Ras somatic mutations predict resistance to mAbs targeting epidermal growth factor receptor (EGFR). Relationships between K-Ras mutations and EGFR status have not been examined so far. We analyzed relationships between K-Ras mutations and EGFR tumoral status based on EGFR germinal polymorphisms, gene copy number and expression. METHODS Eighty colore...

BACKGROUND Although Ki-ras and TP53 mutations have probably been the genetic abnormalities most exhaustively implicated and studied in colorectal cancer (CRC) progression, their significance in terms of disease relapse and overall survival has not yet clearly been established. PATIENTS AND METHODS A prospective study was carried out on paired tumor and normal colon tissue samples from a conse...