The tumor selectivity of alkylating agents that produce guanine O6-chloroethyl (laromustine and carmustine) and O6-methyl (temozolomide) lesions, depends upon O6-methylguanine-DNA methyltransferase (MGMT) activity being lower in tumor than in host tissue. Despite the established role of MGMT as a tumor resistance factor, consensus on how to assess MGMT expression in clinical samples is unsettle...

REV1, a Y family DNA polymerase (pol), is involved in replicative bypass past DNA lesions, so-called translesion DNA synthesis. In addition to a structural role as a scaffold protein, REV1 has been proposed to play a catalytic role as a dCTP transferase in translesion DNA synthesis past abasic and guanine lesions in eukaryotes. To better understand the catalytic function of REV1 in guanine lesi...

The role of the nucleotide excision repair (NER) pathway in removal of DNA ethylation damage was investigated by means of hprt mutational spectra analysis in the NER-deficient Chinese hamster ovary cell line UV5, which lacks ERCC2/XPD, and in its parental cell line AA8. Both cell lines were exposed to ethyl methanesulfonate (EMS) or N-ethyl-N-nitrosourea (ENU). EMS gave a similar dose-dependent...

A highly sensitive and specific method for the detection of 06-methylguanine (O6-meG), O^-methylthymine (O4-meT), and CH-ethylthymine (O4-etT) has been established by combining prefractionation by high-performance liquid chromatography (III'IX '). '•'!' postlabeling, and immunoprecipitation by monoclonal antibodies (PREPI method). DNA was enzymatically hydrolyzed to 2'-deoxynucleoside-3'-mono...

O6-Alkylguanine-DNA alkyltransferase (AGT) is an important DNA repair protein that removes adducts from the O6 position of guanine by transferring them to a cysteine residue within its amino acid sequence. Mammalian AGTs are readily inactivated by incubation with O6-benzyl-guanine (BG), which is an alternative substrate for the protein. To examine this inactivation in more detail and to develop...

In 1989 [15], Huzita introduced the six origami operations that have now become know as the Huzita Axioms (HAs). The HAs, shown in Figure 1, constitute six distinct ways of defining a single fold by bringing together combinations of preexisting points (e.g., crease intersections) and preexisting lines (creases and/or the fold line itself). It has been shown that all of the standard compass-and-...

Normal and malignant cells of the oligodendrocyte lineage show increased sensitivity to alkylating agents compared to astrocytes. One of the most mutagenic DNA lesions formed following exposure to alkylating agents is O6-alkylguanine. To determine whether the increased sensitivity to nitrosoureas seen in oligodendrocytes is due to decreased repair capacity for O6-alkylguanine, removal of this l...

Conventional radiochromatographic procedures for the quantitation of carcinogen/mutagen-induced structural DNA modifications have a number of limitations. Thus, these techniques for the most part require application of radioactively labeled carcinogens and the use of relatively large amounts of DNA for analysis at low levels of DNA modification. Radiochromatographic methods also preclude analys...

Immunotherapy with antibodies (Abs) against the lipopolysaccharide (LPS) of Pseudomonas aeruginosa remains an alternative to serotype-specific LPS-based vaccines due to their limited use and to antibiotics due to the intrinsic resistance to antimicrobials observed in P. aeruginosa. We have chosen a monoclonal Ab (MAb), MF23-1, that binds to the O antigen of the most clinically relevant serotype...

Alkylation of DNA at the O6-position of guanine is one of the most critical events leading to mutation, cancer, and cell death. The enzyme O6-methylguanine-DNA methyltransferase repairs O6-methylguanine as well as a minor methylated base, O4-methylthymine, in DNA. Mouse lines deficient in the methyltransferase (MGMT) gene are hypersensitive to both the killing and to the tumorigenic effects of ...