DIFFERENTIAL EXPRESSION OF WNT GENES IN NORMAL AND FLAT VARIANTS OF PC12 CELLS, A CELL-LINE RESPONSIVE TO ECTOPIC WNT1 EXPRESSION

Wnt genes encode secreted growth factor-like proteins that participate in growth regulation, differentiation and tumorigenesis. Ectopic expr ession of Wnt1 converts the PC12 neural crest-derived rat pheochromocy toma cell line from a round phenotype that express chromaffin markers to flat adherent cells (termed PC12/Wnt1) that do not express them. A pool of spontaneously flat variants of PC12 cells (PC12/flat) is pheno typically similar to the PC12/Wnt1 cells, but does not express Wnt1. H ere we describe the expression of 13 Wnt genes in wild type PC12, PC12 /flat and PC12/Wnt1 cells. Wild type PC12 expressed Wnt3, Wnt3a, Wnt4, Wnt5a, Wnt6, Wnt10a and Wnt11. Compared with expression in wild type cells, both PC12/flat and PC12/Wnt1 cells lost most or all expression of Wnt3a and Wnt4 and gained expression of Wnt7b. Wnt5a and Wnt6 expre ssion was higher in PC12/Wnt1 cells than in PC12 or PC12/flat. Wnt3 wa s expressed at low levels in both PC12 and PC12/flat, but was absent i n PC12/Wnt1 cells. Wnt10a and Wnt11 were approximately equally express ed in the three groups, and Wnt2, Wnt5b, Wnt7a, Wnt10b and endogenous Wnt1 mRNAs were not detected. These results demonstrate that the expre ssion of some Wnt genes changes in PC12 cells upon conversion to the f lat phenotype, and suggest that Wnt1 may modulate expression of severa l other Wnt genes in these cells.