EXPRESSION OF THE NM23-2 NDP KINASE-ALPHA GENE IN RAT MAMMARY AND ORAL-CARCINOMA CELLS OF VARYING METASTATIC POTENTIAL/

Reduced expression of the putative metastasis-suppressor gene, nm23-1, has previously been correlated with high tumour metastatic potential. The involvement of the related and proximally-located nm23-2 gene in the suppression of tumour metastasis, however, has not yet been tested . In this study, we compared nm23-2 RNA levels in cell lines derived f rom three independent rat mammary carcinomas. Northern blot analysis r evealed no correlation between nm23-2 RNA levels and metastatic potent ial in parent or clonal cell lines derived from chemically-induced (MA T 13762, DMBA-8) or spontaneous (BC1) mt mammary carcinomas. Cloning a nd sequencing of an nm23-2 cDNA from metastatic BC1 cells demonstrated that the predicted coding sequence of nm23-2 RNA in these cells was n ot inactivated by mutation. Further analysis showed that the nm23-2 ge ne was not down-regulated in H-ras-transfected metastatic clones or ot her metastatic cell lines derived from a spontaneous rat paraoral squa mous cell carcinoma, B10. The data do not suggest a correlation betwee n nm23-2 gene expression and metastasis-suppression in these tumours.