Mutational Analyses of Connexin 26, Connexin 30 and Connexin 46 as Candidate Tumor Suppressor Genes in Parathyroid Carcinoma

Acquired loss of heterozygosity or deletion on 13q is frequently detected in parathyroid carcinoma, suggesting the presence of a parathyroid tumor suppressor gene in this location. Connexins make up the functional unit of gap junctional intercellular communication (GJIC), forming channels allowing passage of small molecules and ions between adjacent cells. Defects in GJIC have been observed in tumor cells and decreased cyclin D1 expression has resulted from forced connexin expression in cancer cells. Given the evidence suggesting 13q-based connexins as important candidate parathyroid tumor suppressors, we tested this hypothesis by examining the coding regions of connexin 26, connexin 30 and connexin 46 for somatic mutations in 13 parathyroid carcinomas. No mutations, insertions, or microdeletions were detected. Based on the absence of identifiable inactivating mutations, it is highly unlikely that connexin 26, connexin 30 or connexin 46 commonly function as classical tumor suppressor genes in the pathogenesis of parathyroid carcinoma.