Cell Growth & Differentiation, Vol 2, Issue 9 439-445, Copyright © 1991 by American Association of Cancer Research
Overexpression of the retinoblastoma gene in a familial adrenocortical carcinoma
S Warneford, M Townsend, PB Rowe, L Dalla-Pozza and G Symonds
Leukemia Research and Viral Pathology Unit, Children's Hospital, Camperdown, Sydney, Australia.
Tumors derived from a Li-Fraumeni syndrome cancer-susceptible family were
examined for expression of the retinoblastoma susceptibility gene (RB).
Whereas RB expression was normal in a primary breast carcinoma and its
metastases from one member of this family, overexpression of RB was found
in an adrenocortical carcinoma from another family member. This was in
contrast to normal RB expression in normal tissue of this patient, the
adrenocortical adenocarcinoma cell line SW-13, and the fibroblast cell line
MRC-5, and low level RB expression in normal adrenal tissue. The
overexpression in the adrenocortical carcinoma resulted in increased
synthesis of the RB-encoded protein and did not appear to be associated
with RB amplification or rearrangement. This result is novel as it is
usually the loss of expression or production of an altered RB transcript
exhibiting deletions that is associated with carcinogenesis. In light of
the recent discovery of p53 point mutations in the affected Li-Fraumeni
syndrome family members tested, RB overexpression may constitute a
secondary event in Li-Fraumeni syndrome tumorigenesis.