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Hexokinase isoenzyme composition has been noted to vary in different tissues and with the developmental and metabolic status of the cell. Until now these investigations were performed either by isoenzyme electrophoresis or by column chromatography. In this report we described an RNA-PCR method to evaluate the percentage of HK-1 and HK-2 in different rat tissues. Furthermore we applied the method to determine if a shift in isoform composition is detectable in human renal carcinomas compared to normal kidney tissue. In all of our specimens we were able to detect a shift toward HK-2 in the carcinoma specimens. We discuss a possible role for the detection of the shift in isoenzyme composition as a possible marker to discriminate between normal and malignant specimens.

The concentration of mRNA of insulin-like growth factor-II is (IGF-II) much elevated in some embryonic tumours such as Wilms tumour (nephroblastoma). In order to prove whether or not IGF-II is produced by the tumour tissue, IGF-II was extracted from freshly frozen tissue of Wilms tumour and hepatoblastoma. Normal adjacent tissue of kidney and liver was used as a control. The total IGF-II in Wilms tumour was 548.4 +/- 77.4 ng/g (n = 7) compared to 112.8 +/- 38.2 ng/g (n = 5) in kidney. In two hepatoblastomas, it was 96.1 +/- 22.8 ng/g compared to 30.1 +/- 14.2 ng/g in normal liver. Small pieces of fresh primary tissue of several Wilms tumours were successfully transplanted into immunodeficient nude mice. In serum of tumour-bearing mice IGF-II was elevated compared to normal mice. Liver weight of tumour bearing mice was higher than that of control mice (2.29 +/- 0.4 g and 2.02 +/- 0.06 g; P < 0.005). This was also found for kidney weight (0.58 +/- 0.01 g vs. 0.51 +/- 0.01 g in controls, P < 0.001). In contrast, serum glucose (9.73 +/- 0.29 mmol/l compared to 11.80 +/- 0.42 mmol/l in controls, P < 0.0005) was decreased. However, there was no significant difference in nose-tail length of tumour-bearing compared to control mice. These results demonstrate that besides the highly increased IGF-II-mRNA, the synthesis of the peptide IGF-II and its release into circulation are also elevated in Wilms tumour transplanted into nude mice.(ABSTRACT TRUNCATED AT 250 WORDS)

IGF-II may play a decisive role in the development of Wilms tumors since an elevated expression of this important embryonal growth factor has been reported in the majority of nephroblastomas. In our series of 15 typical triphasic or blastemal predominant nephroblastomas slot-blot-hybridization revealed a marked increase of IFG-II-mRNA in the tumor tissue of 11 patients. Compared to normal kidney tissue IGF-II-expression was elevated up to 64 times. Apart from nephroblastoma a number of other embryonal renal tumors with either a much better or much worse prognosis was investigated. A moderately increased expression of IGF-II was noted in 2 congenital mesoblastic nephromas. IGF-II-mRNA was only slightly increased in a clear cell sarcoma of the kidney but was not elevated in 2 malignant rhabdoid tumors of the kidney. In-situ-hybridization allowed precise localization of the markedly increased IGF-II mRNA to blastemal cells. Differentiation to epithelial structures such as tubules or glomeruli or to stromal cells was associated with a marked loss in IGF-II expression.

The incidence of nephroblastoma is increased in a number of syndromes with abnormal growth pattern. Elevated IGF 2-expression has been documented in various Wilms' tumors and a defect in the IGF 2 gene has been noted in 1 case. Southern blot analysis of genomic DNA of nephroblastomas in 5 additional patients after restriction enzyme digest with EcoRI, Pvu II, Pst I and Taq I did not reveal any defect in the IGF 2 gene. Slot blot analysis however showed marked overexpression of IGF 2-mRNA reaching up to more than 25 times the level expressed in unaffected kidney tissue adjacent to the tumor and in normal kidney tissue used as controls.