This is the first reported case of simultaneous SDHB and TP53 germline mutations occurring in an individual with a highly aggressive clinical course of pheochromocytoma.
We conclude that, although there is frequent loss of the p53 locus on 17p, the p53 gene does not appear to play a major role in pheochromocytoma tumorigenesis.
The role of p53 tumor suppressor gene in the pathomechanism of adrenal tumors was investigated by measuring p53 protein and its messenger ribonucleic acid (mRNA) in 12 normal human adrenals as well as in 56 adrenal tumors (7 aldosterone-producing adenomas, 5 adrenocortical adenomas causing Cushing's syndrome, 19 non-hyperfunctioning adrenocortical adenomas, 5 adrenocortical carcinomas, 12 pheochromocytomas, 3 myelolipomas, 4 ganglioneuromas and 1 hemangioma).
Our findings indicate that mutations in the TP53 gene are an uncommon event in the tumorigenesis of pheochromocytomas and medullary thyroid carcinomas.
The regions of allelic deletion on chromosome 11 (11pter-p13), 17 (17pter-p11.2), and 13 (13q) encompass known tumour suppressor loci (WTI, TP53, RBI) which must therefore be candidates for genes contributing to MTC and Pheo development.
On the basis of a previous report that genes on chromosome 17p were not deleted in MTCs and were relatively infrequently deleted in pheochromocytomas, our results suggest that the p53 gene is not involved in tumorigenesis of MTC or pheochromocytoma.
To explore the possible role of tumor suppressor genes in endocrine tumors, we tested 41 pheochromocytomas (34 sporadic and 7 familial) and 11 medullary thyroid cancers (MTC) (10 sporadic and 1 familial) for LOH near a variety of potentially important genetic loci: (a) the multiple endocrine neoplasia type 2A (MEN 2A) locus on chromosome 10; (b) the von Hippel-Lindau locus on 3p; and (c) the p53 and neurofibromatosis 1 loci on 17.