We have developed a generalized approach, using two hybrid interactions, to isolate Ha-Ras effector loop mutations that separate the ability of Ha-Ras to interact with different downstream effectors. These mutations attenuate or eliminate Ha-ras(G12V) transformation of mammalian cells, but retain complementary activity, as demonstrated by synergistic induction of foci of growth-transformed cell...

UV radiation is a potent DNA-damaging agent and a known inducer of skin cancer in experimental animals. To elucidate the role of oncogenes in UV carcinogenesis, we analyzed UV-induced murine skin tumors for mutations in codon 12, 13, or 61 of Ha-ras, Ki-ras, and N-ras oncogenes by amplification of genomic tumor DNAs by the polymerase chain reaction followed by dot-blot hybridization to syntheti...

O-Methylguanine DNA methyltransferase (MGMT) is a DNA repair protein that removes mutagenic and cytotoxic adducts from the O position of guanine. O-Methylguanine mispairs with thymine during replication, and if the adduct is not removed, this results in conversion from a guanine-cytosine pair to an adenine-thymine pair. In vitro assays show that MGMT expression avoids G to A mutations and MGMT ...

O6-methylguanine DNA methyltransferase (MGMT) is a DNA repair protein that removes mutagenic and cytotoxic adducts from the O6 position of guanine. O6-methylguanine mispairs with thymine during replication, and if the adduct is not removed, this results in conversion from a guanine-cytosine pair to an adenine-thymine pair. In vitro assays show that MGMT expression avoids G to A mutations and MG...

K-ras point mutations are often detected in part of the lung carcinomas. For the validation of a highly sensitive and rapid assay for known point mutations, Point-EXACCT (Biochim Biophys Acta 1998; 1379:42-52), we analyzed 89 non-small cell lung carcinomas and compared the results with two sequencing methods. No point mutations were found with double-stranded sequencing. Single-stranded sequenc...

Ras oncogenes owe their transforming properties to single point mutations in the sequence coding for the active site of the p21 protein. These mutations lead to changes in cellular proliferation and induce tumorigenic properties. Point mutations represent a well-defined target for antisense oligonucleotides that can specifically suppress the translation of the targeted mutant mRNA. We show that...

BACKGROUND Mutations in ras genes are commonly found in human cancers and in animal models. Although mutations at codons 12, 13, and 61 of H-, N- and K-ras genes can activate their oncogenic function, mutations at codon 12 of K-ras are the most common mutations found among the three ras genes in human cancers. To investigate whether codon 12 of human K-ras is especially susceptible to carcinoge...

To investigate the role of tobacco smoking and asbestos fibers in the etiology of human lung cancer, we examined the activating point mutations in the K-ras oncogene in DNA samples from 49 patients. Mutations were found more often in tissue from adenocarcinomas (12/21) than in tissue from tumors other than nonadenocarcinomas of the lung (3/28). Among the adenocarcinoma patients, asbestos exposu...

An interaction with the Ras proto-oncogene product is a requirement for Raf-1 activation in many signaling cascades. The significance of this interaction is demonstrated by the fact that a mutation preventing the Ras-Raf interaction severely impairs the function of both mammalian (Raf-1) and Drosophila (D-Raf) Raf proteins. In D-Raf, however, dominant intragenic mutations have been identified t...