Mutation analysis of the PTEN/MMAC1 gene in cancers of the digestive tract

The 10q23.3 gene PTEN (phosphatase and Tensin homologue deleted on chromoso me 10) or MMAC1 (mutated in multiple advanced cancers 1) was recently repor ted to undergo frequent mutation, including mutations and deletions in mult iple advanced cancers. This study showed that the aberrant transcripts of t his gene are frequently found in cancers of the digestive tract, paired non -cancerous tissues and normal peripheral mononuclear cells. Sequence analys is of the aberrant transcripts revealed three types of deletions: (i) a del etion junction with a splicing-like donor or acceptor sequence; (ii) severa l-base homology near or between the donor acceptor site at the deletion jun ction; and (iii) deletion with insertion. From these results, it is suggest ed that aberrant transcripts of PTEN/MMAC1 found by nested reverse transcri ption-polymerase chain reaction are a common (or natural) phenomenon unrela ted to oncogenesis. The mechanism producing these aberrant transcripts need s further investigation. Using single-strand conformation polymorphism and direct sequencing to analyse for small base changes of the genomic DNA of t he PTEN/MMAC1 gene revealed no point mutations or small base changes. (C) 1 999 Elsevier Science Ltd. All rights reserved.