Expression of the insulin-like growth factor system and cancer progression in hormone-treated prostate cancer patients.

BACKGROUND: The insulin-like growth factor (IGF) system, which is composed of two ligands (IGF-I and IGF-II), two receptors (IGFR-I and IGFR-II) and six binding proteins (IGFBP-1 to -6), plays an important role in cell biology. To identify the main components in the IGF system that contribute to human prostate cancer progression after hormone therapy, mRNA expression of the IGF system in human prostate cancer tissue was systematically examined.
METHODS: Expression of the IGF system in 24 carcinomas obtained from total prostatectomies after hormone therapy was examined. Expression levels of mRNA of each component of the IGF system were analyzed by quantitative reverse transcription-polymerase chain reaction procedures and compared with clinicopathologic parameters.
RESULTS: Expression of the IGF system, except IGFBP-1, was detected in all prostate cancer tissue samples. The expression of IGF-II and IGFBP-2 significantly correlated with pathologic stage, lymph node metastasis, histologic differentiation and serum prostate-specific antigen (PSA) levels after hormone therapy. However, expression of IGF-I was significantly lower in locally advanced prostate cancer tissue than in tissue from the early stage. Expression of IGFBP-5 was significantly related to only serum PSA levels after hormone therapy.
CONCLUSIONS: In the IGF system, IGF-II and IGFBP-2 play a role in human prostate cancer progression and their increased expression is a possible candidate for a prognostic indicator in hormone-treated prostate cancer patients.