Genetics and cancer

Genetic basis of pituitary adenoma invasiveness: a review

Compatible with contemporary paradigms of the role of genetic aberrations in the progression of human tumors, the growth of pituitary tumors into a state of invasiveness appears to be due to genetic alterations. Amplification of H-ras and c-myc oncogenes and mutations of p53, nm23 and Rb genes have been identified disproportionately more in aggressive tumors and, in the case of Rb gene, in pituitary carcinomas, providing evidence that amplification of these oncogenes (H-ras and c-myc) and inactivation of tumor suppressor genes (p53, nm23 and Rb) seem to be at least one mechanism by which pituitary tumors progress. The current level of management of invasive pituitary adenomas should become more comprehensive as the advances in our understanding of genetic basis of pituitary adenoma invasiveness becomes translated into development of novel chemotherapy or gene transfer technique.

The application of DNA recombinant technology to the analysis of the human genome and genetic disease

Recombinant DNA technology permits the isolation of libraries of DNA sequences corresponding to either the whole genome of an individual or the expressed sequences of a given cell type. Gene-specific probes isolated from these libraries may be used for the identification of DNA sequences in the genome necessary for normal gene function and for the study of the consequences of mutations and rearrangements in these sequences which give rise to the clinical symptoms in genetic disease. DNA sequence polymorphisms can be used to construct a genetic linkage map of the entire human genome. This allows the development of antenatal diagnoses for monogenic diseases even in the absence of an understanding of the biochemical defect.

On the possibility of metabolic control of replicon "misfiring": relationship to emergence of malignant phenotypes in mammalian cell lineages

Constraints of a multireplicon chromosomal organization and of the necessity to maintain constant gene dosages demand that each origin of replication in a eukaryotic cell "fire" (initiate replication) only once per cell cycle. The central idea of this work is that a low probability of an extra ("illegitimate") round of DNA replication (called below "replicon misfiring") within any given chromosomal domain could be increased by certain substances of either intra- or extracellular origin. The term " "firone" is proposed for such a substance. It is shown that existence of firones could greatly speed up evolution of cellular systems under selection pressure, a developing tumor being one example of such a system. Experimentally testable predictions of the firone hypothesis are discussed.