Inhibition of glutaminase expression by antisense mRNA decreases growth and tumourigenicity of tumour cells

Phosphate-activated glutaminase has a critical role in rumours and rapidly dividing cells and its activity is correlated with malignancy. Ehrlich asci tes tumour cells transfected with the pcDNA3 vector containing an antisense segment (0.28 kb) of rat kidney glutaminase showed impairment in the growt h rate and plating efficiency, as well as a shortage in the glutaminase pro tein and activity. The C-terminal segment used is well conserved in all glu taminase sequences known. The transfected cells, named 0.28AS-2, displayed remarkable changes in their morphology compared with the parental cell line . The 0.28AS-2 cells also lost their tumourigenic capacity in vivo. Control mice developed an ascitic tumour, with a lifespan of 16 +/- 1 days, when i noculated with 10(7) cells/mouse; on the contrary, animals inoculated with transfected cells up to 2.5 times the cell numbers of control mice did not develop tumours and behaved as healthy animals. The ability to revert the t ransformed phenotype of antisense-transfected cells confirms the relevance of glutaminase in the transformation process and could provide new ways for the study of gene therapy.