Anti-TNF therapy and malignancy - a critical review.

The roles of tumour necrosis factor (TNF) and anti-TNF therapy in malignancy are reviewed, including an overview of baseline risk factors for malignancy in inflammatory diseases and the incidences of malignancies observed in clinical trials of an anti-TNF-a therapy, infliximab. The preclinical data and early clinical experience presented for infliximab do not provide evidence for a causal relationship between TNF-a antagonism and the development of lymphoid or nonlymphoid cancers.

Analysis of site-specific binding of (+/-)-anti-benzo[a]pyrene diol epoxide to restriction fragments of pBR322 DNA via photochemical mapping.

The binding sites and relative reactivity of (+/-)-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+/-)-anti-BPDE] covalently bound to restriction fragments of pBR322 DNA are determined. (+/-)-anti-BPDE-modified DNA undergoes a photodissociation at the site of these adducts when irradiated with 355-nm laser light, resulting in a scission of the DNA sugar-phosphate backbone producing DNA fragments similar to those of Maxam-Gilbert sequencing reactions. The binding sites of (+/-)-anti-BPDE with each DNA base are determined by sequencing gel analysis of the BPDE-mediated photolysis and laser densitometry of the resulting banding patterns. This technique was used to analyze the binding of (+/-)-anti-BPDE to the 5' and 3' strands of the EcoRI/EcoRV and BamHI/SalI restriction fragments of pBR322 DNA. The reactivity of (+/-)-anti-BPDE to guanine bases within guanine-rich regions of DNA is enhanced by as much as a factor of 17 relative to the least reactive guanines which are flanked by non-guanine bases. The results also show enhanced photocleavage of the backbone corresponding to non-guanine bases in guanine-rich regions. These results suggest either that non-guanine basis in guanine-rich regions are more reactive than identical bases in other regions of the restriction fragment or that photocleavage of the backbone occurs adjacent to a BPDE-modified guanine. The binding profiles of (+/-)-anti-BPDE to pBR322 DNA at a binding density of 0.52 and 0.93 BPDE adduct per strand gave essentially identical binding patterns.(ABSTRACT TRUNCATED AT 250 WORDS)

Mapping of (+/-)-anti-benzo[a]pyrene diol epoxide adducts to human c-Ha-ras1 protooncogene.

The relative reactivity of the chemical carcinogen (+/-)-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+/-)-anti-BPDE] to the guanine bases of the first two coding exons of the human c-Ha-ras1 protooncogene is determined to test if (+/-)-anti-BPDE reactivity is correlated with mutations reported for human c-Ha-ras1 protooncogene activation. Plasmid DNA containing the sequence for the human c-Ha-ras1 gene is modified with (+/-)-anti-BPDE to provide approximately 1 covalent adduct per 250 bp. High-resolution mapping of the covalent adducts is achieved by laser-induced photolysis of 32P-labeled restriction fragments of the BPDE-modified plasmid DNA. The (+/-)-anti-BPDE binding profiles to exons 1 and 2 of the human c-Ha-ras1 protooncogene show enhanced reactivity to guanine-rich regions. The guanine bases of oncogene-activating codons 12 (GGC) and 13 (GGT) are 5 times more reactive than the least reactive guanine analyzed within this region of the gene. The guanine base of oncogene-activating codon 61 (CAG) exhibits intermediate reactivity relative to the guanines analyzed within this region of the gene. Although preferential chemical reactivity plays a role in the activation of the c-Ha-ras1 protooncogene, the in vivo activation of the c-Ha-ras1 protooncogene by (+/-)-anti-BPDE is a complex process, with other important factors involved in the chemically induced activation.