1. 1 SCOPE OF BOOK n explosion of novel findings in the past decade has
contrib- A uted to the great progress toward understanding the biology
of human cancers. Much of this progress can be attributed to our abil-
ity to dissect many biological processes at the molecular level. Most
spectacular is the technology of molecular biology that allows identi-
fication and characterization of genes that participate in the genesis
of human cancers. Three major groups of genes appear to play out the
drama of cancer development: tumor suppressor genes, mis- match repair
genes, and oncogenes. The tumor suppressor genes 1 encode products that
are inhibitory to cell proliferation. The loss of these inhibitors, by
mutation or deletion, can unleash cells from their restraints to
proliferate. Mutations in the mismatch repair 2 10 genes also have been
implicated in tumorigenesis. - The inability of cells to repair
spontaneously occurring mutations leads to genom- ic instability and
could potentially result in the accumulation of car- cinogenic DNA
lesions. Finally, activation of proto-oncogenes, which are normal
cellular genes, into oncogenes could accelerate the 11 processes of cell
proliferation. c-myc was one of the very first proto- oncogenes to be
identified and because it normally plays pivotal roles in both cell
proliferation and cell death has enticed many to investigate the
molecular mechanisms by which it transforms cells.