Rat gap junction connexin-30 inhibits proliferation of glioma cell lines

Connexins, the structural components of gap junctions, control cell growth and differentiation and are believed to belong to a family of tumour suppre ssor genes. Studies on connexin localization in brain showed that several o f these proteins were expressed in distinct compartments of the brain in a cell-type specific manner, indicating that different gap junctions play spe cific roles in the physiology of the mammalian brain. In this report, we fi rst cloned rat connexin-30 cDNA from brain and showed that it was expressed in long-term primary culture of rat astrocytes, In order to examine the po tential role of connexin-30 in tumour cell proliferation, we transfected th e connexin-30 cDNA into two rat glioma cell lines (9L and C6) which have lo st its expression. Transfected clones adequately expressed membrane-bound c onnexin-30 protein. Connexin-30-expressing clones showed slower growth, low er DNA synthesis and reduced proliferation in soft agar as compared with th e parental and control cells. We concluded that connexin-30 may also probab ly be considered as a tumour suppressor in rat gliomas.