Monoclonal antibody against rat renal cell tumor-associated antigen as a new tool for the analysis of renal tumorigenesis

Establishment and characterization of three new rat renal cell carcinoma cell lines from N-ethyl-N-hydroxyethylnitrosamine-induced basophilic cell tumors

Three new rat cell lines (designated as BP13, BP30 and BP36B), derived from rat basophilic-type renal cell carcinomas induced with N-ethyl-N-hydroxyethylnitrosamine, were established and characterized. Passaged up to 100 times in vitro for 3 years, each cell line forms epithelial monolayers with cell cycles for BP13, BP30 and BP36B of 29, 21 and 17 h, respectively. Positive glucose-6-phosphate dehydrogenase (G6PD) and gamma-glutamyltransferase (gamma-GT) activity in their cytoplasm, but negative succinate dehydrogenase (SD) and slightly positive carbonic anhydrase type II (CA) localization indicates an origin from proximal tubules. Ultrastructural examination showed the presence of variable numbers of mitochondria and many microvilli and intracellular junctions on the plasma membrane. BP13 and BP30 were found to be tetraploid and BP36B diploid. BP13 has one marker chromosome 15p+, and BP36B an isochromosome of 1q. Anchorage-independent growth and tumorigenicity in immunosuppressed nude mice of BP13 and BP36B, but not BP30, proved their neoplastic nature. These three cell lines should provide useful tools for studying the biological characteristics of renal cell tumors.

Tissue and serum pepsinogen I and II in gastric cancer identified using immunohistochemistry and rapid ELISA

AIMS

To investigate the immunohistochemical expression and the serum concentrations of pepsinogen I and II in different histological types of gastric cancer as compared with other gastric disorders.

METHODS

Formalin fixed, paraffin wax embedded tissue specimens of 38 gastric cancers obtained from surgical cases were used for the immunohistochemical studies performed with the avidin-biotin complex method using monoclonal antibodies against purified pepsinogen I and II. Pepsinogen concentrations from serum obtained from the above patients, from patients with various other gastric disorders, and from normal controls were measured with a rapid non-radioactive one step enzyme linked immunosorbent assay (ELISA).

RESULTS

Eight of 38 (21%) and seven of 38 (18%) gastric carcinomas showed immunoreactivity to pepsinogen I and pepsinogen II, respectively, without any correlation to histological classification or differentiation. Decreased pepsinogen I concentrations and low pepsinogen I:II ratios were found specifically in cases of gastric carcinoma and polyp, in good accordance with the immunohistochemical results.

CONCLUSIONS

Low serum pepsinogen I concentrations and a low pepsinogen I:II ratio are predictive of gastric neoplasia, correlating with low tissue immunoreactivity to monoclonal antibodies raised against pepsinogen I and II. For mass screening of gastric disease including carcinoma, ELISA using a one step immunoassay performed in the present study is a rapid and reliable non-radioactive method of detecting serum pepsinogen. In addition, immunohistochemical studies showed that pepsinogen production may be increased or diminished as a result of tumour histogenesis, depending on the area of origin and the processes of cell transformation and dedifferentiation.

Inhibitory effect of potassium citrate on rat renal tumors induced by N-ethyl-N-hydroxyethylnitrosamine followed by potassium dibasic phosphate

Potassium dibasic phosphate (PDP) was administered at a concentration of 10% by weight in basal diet to unilaterally nephrectomized Wistar rats previously given 1000 ppm N-ethyl-N-hydroxyethyl-nitrosamine (EHEN) in the diet for 2 weeks. To study the effect of alkalinization on renal mineralization, some animals concomitantly received 5% potassium citrate (PC). Feeding PDP alone promoted adenomatous hyperplasias, which were regarded as preneoplastic lesions, as well as renal cell tumors in EHEN-initiated rats, whereas the addition of PC to PDP diets reduced the promoting effect. Histopathology, serum biochemistry and urinalysis indicated retardation of renal calcium crystallization by PC. Two other phosphate salts, sodium phosphate (SP) and calcium phosphate (CP), were also administered. SP showed a slight promoting effect on adenomatous hyperplasias and a 2-fold increase in the yield of renal cell tumors, while CP induced a clear reduction of both lesions, over EHEN alone. The promoting effects of both PDP and SP and the inhibitory effect of PC were somewhat correlated to 5-bromo-2'-deoxyuridine labeling indices, the degree of nephropathy, and mineralization in the kidney. Immunohistochemically, the nephropathy induced by phosphate salts was not linked to alpha 2u-globulin. A pathogenesis for renal carcinogenesis is suggested in which nephropathy associated with mineralization enhances the development of renal cell tumors.

Vimentin metaplasia in renal cortical tubules of preneoplastic, neoplastic, aging, and regenerative lesions of rats and humans

Vimentin expression was studied immunohistochemically in renal cortical tubules of untreated male rats of various ages, rats exposed to toxins (barbital sodium, folic acid) and carcinogens (streptozotocin, N-bis(2-hydroxypropyl)nitrosamine, barbital sodium, and in humans of various ages with or without renal epithelial tumors. Fetal, neonatal, and young adult rats did not express vimentin in renal cortical tubules. Regenerative renal tubular lesions from rats with aging nephropathy and from rats with toxic nephropathy both expressed vimentin. Mitogenic lesions induced by folic acid at 24 hours, however, were not immunoreactive for vimentin. Carcinogen-induced preneoplastic renal cortical tubular lesions in rats were most often focally immunoreactive whereas strong vimentin expression was found in almost all induced renal tumors. In kidneys of three children (younger than 2 years of age), vimentin was not found in renal cortical tubular cells except in rare individual cells in one case. Vimentin was abundant in basophilic regenerative tubules in kidneys of aged individuals, however. Most (7/10) human renal carcinomas and latent preneoplastic or neoplastic renal tubular lesions found incidentally at autopsy (2/4) showed vimentin expression. The authors suggest that the switching to vimentin expression in phenotypically normal renal cortical tubular cells in rats and humans, which do not usually express the intermediate filament protein vimentin, should be considered vimentin metaplasia. Vimentin expression is dissociated from increased cell proliferation in hyperplastic and neoplastic lesions, however. Instead the degree of dedifferentiation of the tubule cells and changes in phenotype were associated with vimentin expression.