Chromosomal abnormalities and gene amplification in renal cancers induced in rats by nickel subsulfide

Nickel subsulfide (alpha Ni3S2) was administered to male Fischer-344 rats by unilateral intrarenal (i.r.) injection (20 mg per rat) to establish the time-course of alpha Ni3S2-induced erythrocytosis and to identify chromosomal abnormalities and molecular genetic aberrations in ensuing renal cancers. Blood hematocrit values were increased in alpha Ni3S2-treated rats during two to 36 weeks post-injection, attained a maximum of 77 percent (SD +/- 5) at 16 weeks (vs 51 +/- 3 percent in vehicle controls), and returned to baseline at 40 weeks. Within 21 months, malignant neoplasms (five sarcomas, one carcinoma) occurred in the injected kidneys of 6/28 alpha Ni3S2-treated rats (vs 0/13 controls). Cytogenetic analyses of direct preparations or primary cell cultures showed prominent chromosomal aberrations in three neoplasms, with rearranged marker chromosomes, polyploidy, and in one case an homogeneously staining region (HSR). Assays for gene amplification were performed with probes for murine erythropoietin (EPO) gene and H-ras, c-fos, c-myc, and N-myc oncogenes, using deoxyribonucleic acid (DNA) samples isolated from injected kidneys and renal neoplasms, as well as from the contralateral, non-injected kidneys. No consistent pattern was found; in one sarcoma, N-myc was amplified six-fold and c-fos was amplified two-fold; in another sarcoma, H-ras, c-fos, and EPO were amplified two-fold. This study shows that (a) karyotypes of 3/6 renal neoplasms of alpha Ni3S2-treated rats contained prominent marker chromosomes, (b) oncogene amplification was noted in 2/6 renal neoplasms, and (c) the EPO gene was not consistently amplified in DNA from the injected kidneys of alpha Ni3S2-treated rats during the initiation of erythrocytosis, or in subsequent renal neoplasms.