title: Serum interleukin-6 in patients with metastatic bone disease: correlation with cystatin C.
abstract: The clinical significance of serum interleukin-6 (IL-6) and its correlation with cystatin C (Cyst C), an endogenous inhibitor of cysteine proteinase cathepsin K, was investigated by immunoassays in patients with bone metastasis from breast cancer (BCa) or prostate cancer (PCa). Additional studies were also performed in these patients to assess the effects of zoledronic acid (ZA) administration on the circulating levels of these molecules. Mean IL-6 and Cyst C serum concentrations were significantly increased in BCa patients and in patients with primary osteoporosis (PO) compared to healthy subjects (HS). However, Cyst C, but not IL-6, resulted significantly more elevated in BCa patients than in PO patients. Furthermore, in BCa patients no correlation was highlighted between IL-6 and Cyst C or between these molecules and some clinicobiological parameters of malignant progression. Mean IL-6 levels were also higher in PCa patients and in patients with benign prostatic hyperplasia (BPH) than in HS while Cyst C resulted significantly higher in PCa but not in BPH patients as compared to HS. In PCa patients, a positive correlation was highlighted between IL-6 and number of bone metastases or serum prostate-specific antigen but not with the Gleason score. Conversely, Cyst C levels did not correlate with any of the parameters considered above or with IL-6. Receiver operating characteristic (ROC) curve analysis showed a poor diagnostic accuracy of IL-6 and Cyst C to detect BCa patients with skeletal metastases while, in PCa patients, only IL-6 showed a fair diagnostic performance in this respect. Finally, the administration of ZA to patients with bone metastases induced a statistically significant increase of serum IL-6 and Cyst C only PCa patients with bone metastasis. These data indicate that IL-6 and Cyst C may be regarded as novel targets for cancer treatment and as markers of increased osteoblastic activity associated to bisphosphonate treatments in PCa patients with bone metastases.
authors.affiliation: Department of Surgery and Oncology, Laboratory of Experimental Chemotherapy and Tumor Markers, Policlinico Universitario P. Giaccone, 90127 Palermo, Italy.
authors.forename: Francesca M
authors.initials: FM
authors.lastname: Tumminello
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Badalamenti
authors.forename: Lorena
authors.initials: L
authors.lastname: Incorvaia
authors.forename: Fabio
authors.initials: F
authors.lastname: Fulfaro
authors.forename: Calogero
authors.initials: C
authors.lastname: D'Amico
authors.forename: Gaetano
authors.initials: G
authors.lastname: Leto
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood; D050071:Bone Density Conservation Agents / Q000627:therapeutic use; D001859:Bone Neoplasms / Q000097:blood* / Q000188:drug therapy / Q000556:secondary*; D001943:Breast Neoplasms / Q000097:blood / Q000150:complications / Q000473:pathology*; D055316:Cystatin C / Q000097:blood*; D004164:Diphosphonates / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000627:therapeutic use; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000097:blood / Q000150:complications; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000150:complications / Q000473:pathology*; D012372:ROC Curve; D000077211:Zoledronic Acid
chemical_list: D014408:Biomarkers, Tumor; D050071:Bone Density Conservation Agents; D055316:Cystatin C; D004164:Diphosphonates; D007093:Imidazoles; D015850:Interleukin-6; D000077211:Zoledronic Acid; D017430:Prostate-Specific Antigen