Isolation and properties of lead-resistant variants of rat glioma cells

Glial cells are thought to protect neurons from heavy-metal toxicity. To gain a better understanding of mechanisms of protection against lead compounds, a number of lead-resistant C6 rat glioma cell sublines have been isolated. After 8 mo of growth in the absence of lead nitrate, three sublines still maintain their lead-resistant phenotype. None of the lead-resistant sublines are cross-resistant to Cd(II) or Ni(II), but all are cross-resistant (in varying degrees) to Hg(II), As(III), Sb(III), and Sn(II), and one is resistant to trimethyl tin. No inducible lead resistance is seen in any glioma line. One subline has been used to create cell-cell hybrids with wild-type cells. The hybrids exhibit dominance of the lead-resistant phenotype. To identify and analyze altered gene expression at the mRNA level in the lead-resistant sublines, the differential display technique was used. Numerous differences are seen between amplified fragments from wild-type and lead-resistant cells. Candidate clones are now being analyzed to confirm the differential expression and to isolate cDNAs that confer lead resistance.