[A study of DNA polymerase beta mutation in human esophageal cancer].

Objective: To investigate whether DNA polymerase beta (POLB) gene mutations occur in esophageal cancer.

Methods: Thirty specimens of esophageal squamous epithelial cancer were resected during operation. A piece of cancer tissue and a piece of juxtacancerous tissue were taken from each specimen. Fourteen specimens of preinvasive esophageal carcer were obtained by esophagoscopy. Reverse transcription polymerase chain reaction (RT-PCR), single-strand conformation polymorphism (SSCP) and sequence analysis were used to examine the DNA polymerase beta genes. DNASIS and OMIGA softwares were used for sequencing.

Results: Obvious mutation was detected by SSCP in 13 of the 30 esophageal infiltrative cancer tissues (with a mutation rate of 43.3%) and in only 1 of the 30 juxtacancerous normal tissues from the preinvasive cancer group, obvious mutation was detected by SSCP in 5 of the 14 preinvasive esophageal cancer tissues (with the mutation rate of 35.7%). In addition, obvious mutation was also detected in one specimen of hyperplasia of squamous epithelium. Within 7 esophageal cancer specimens, 58 bp (177nt to 234nt) deleted mutation of POLB was found. There were 8 point mutation forms: (1) A --> G at 375nt (Ile --> Val) (2) T --> C at 454nt (Phe --> Ser) (3) G --> T at 462nt (Glu --> terminal code) (4) G --> A at 466nt (Gly --> Glu) (5) A --> T at 613nt (Lys --> Ile) (6) G --> C at 648nt (Gly --> Arg) (7) A --> G at 660nt (Arg --> Gly), and (8) A --> G at 670nt (Glu --> Gly).

Conclusion: DNA polymerase beta gene mutations are discovered in human esophageal carcinoma for the first time. It may be related to the development of esophageal cancer, suggesting that POLB activity may be changed.