Tumor suppressor gene mutations in TSG101, FHIT, and PTEN/MMACl were found
in many types of cancer and the defects in these genes are responsible for
the tumor development. Since aberrant transcripts of these genes were also
identified in normal tissues, the significance of these mutations in carcin
ogenesis has become a controversy. To determine large deletions or other al
terations in these genes, we analyzed the integrity of their transcripts in
both cancerous tissues and the matched normal tissues. More than 400 trans
cripts derived from at least eight different types of tissue were analyzed
using nested RT-PCR and direct sequencing. High frequency of abnormal trans
cripts of all three genes occurred in both cancerous and the: normal tissue
s. We believe that these aberrant transcripts do not relate to cancer devel
opment. These aberrant transcripts may be imperfect products of splicesome
that occurs rarely but was amplified by nested RT-PCR. They may be also gen
erated from alternative splicing due to the exonic splicing elements of the
gene.