Prostatic
adenocarcinoma commonly metastasizes to bone. Unlike most other bony secondaries, the majority of skeletal prostatic
metastases are osteoblastic rather than osteolytic in nature. Several
growth factors which are known to stimulate bone formation are expressed in benign and malignant prostate cells, but none has been specifically linked to osteosclerotic
metastases.
Bone morphogenetic proteins (BMPs) induce ectopic bone formation in vivo. We have reported previously that
BMP-6 mRNA and
protein are expressed in the majority of primary prostatic
carcinomas with established skeletal
metastases but rarely in clinically organ-confined tumours. This study examines the expression of
BMP-6 mRNA in matched prostatic primary and secondary bony lesions and in isolated skeletal
metastases from prostatic
adenocarcinomas, as well as other common human
malignancies, by in situ hybridization.
BMP-6 mRNA was detected in 11 out of 13 bone
metastases from prostate
carcinoma and in three paired samples of primary prostate
carcinoma and matching skeletal
metastasis. Weak signals for
BMP-6 were also present in 5 out of 17 skeletal deposits from non-prostatic
malignancies.
BMP-6 mRNA appears to be strongly expressed in prostatic
adenocarcinomas, both in the primary tumour and in bone
metastases. It is also expressed, though less frequently, in skeletal
metastases from other human
carcinomas. Our findings suggest that
BMP-6 may hold potential as an attractive marker and possible mediator of skeletal
metastases, particularly in prostate
carcinoma.