Human connexin 37 is polymorphic but not mutated in tumours.

Connexins are phylogenetically conserved proteins responsible for gap junctional intercellular communication (GJIC). In tumours, GJIC is frequently disrupted. We have tested the hypothesis that the connexin 37 (Cx37) gene might be mutated in human tumours from tissues in which the Cx37 gene is known to be expressed. Eight lung adenocarcinomas and 18 sporadic breast carcinomas were analysed. While most tumours had GTA at codon 130, a base change GTA-->ATA converting valine into isoleucine was found in three breast cancers (one homozygous for ATA) and two lung tumour samples. However, screening of normal DNA from the same patients and DNA from 42 healthy donors revealed that such base change also exists in normal tissue. Thus, we conclude that there is polymorphism of the connexin 37 gene in the human population. This is the first finding of polymorphism in the connexin gene family.