Characterization of prostate cancer bone metastases according to expression levels of steroidogenic enzymes and androgen receptor splice variants

• Background: Intra-tumoral steroidogenesis and constitutive androgen receptor (AR) activity have been associated withcastration-resistant prostate cancer (CRPC). This study aimed to examine if CRPC bone metastases expressed higher levels ofsteroid-converting enzymes than untreated bone metastases. Steroidogenic enzyme levels were also analyzed in relation toexpression of constitutively active AR variants (AR-Vs) and to clinical and pathological variables. Methodology/Principal Findings: Untreated, hormone-naıve (HN, n = 9) and CRPC bone metastases samples (n = 45) wereobtained from 54 patients at metastasis surgery. Non-malignant and malignant prostate samples were acquired from 13prostatectomy specimens. Transcript and protein levels were analyzed by real-time RT-PCR, immunohistochemistry andimmunoblotting. No differences in steroidogenic enzyme levels were detected between CRPC and HN bone metastases.Significantly higher levels of SRD5A1, AKR1C2, AKR1C3, and HSD17B10 mRNA were however found in bone metastases thanin non-malignant and/or malignant prostate tissue, while the CYP11A1, CYP17A1, HSD3B2, SRD5A2, and HSD17B6 mRNAlevels in metastases were significantly lower. A sub-group of metastases expressed very high levels of AKR1C3, which wasnot due to gene amplification as examined by copy number variation assay. No association was found between AKR1C3expression and nuclear AR staining, tumor cell proliferation or patient outcome after metastases surgery. With only oneexception, high AR-V protein levels were found in bone metastases with low AKR1C3 levels, while metastases with highAKR1C3 levels primarily contained low AR-V levels, indicating distinct mechanisms behind castration-resistance in individualbone metastases. Conclusions/Significance: Induced capacity of converting adrenal-gland derived steroids into more potent androgens wasindicated in a sub-group of PC bone metastases. This was not associated with CRPC but merely with the advanced stage ofmetastasis. Sub-groups of bone metastases could be identified according to their expression levels of AKR1C3 and AR-Vs,which might be of relevance for patient response to 2nd line androgen-deprivation therapy.

Ämnesord

Medical and Health Sciences  (hsv)

Basic Medicine  (hsv)

Medicin och hälsovetenskap  (hsv)

Medicinska grundvetenskaper  (hsv)

Medical and Health Sciences  (hsv)

Clinical Medicine  (hsv)

Cancer and Oncology  (hsv)

Medicin och hälsovetenskap  (hsv)

Klinisk medicin  (hsv)

Cancer och onkologi  (hsv)

Molecular Medicine  (umu)

molekylär medicin (medicinska vetenskaper)  (umu)

Nyckelord

prostate cancer

bone metastases

androgen receptor splice variants

steroidogenic enzymes