Circulating cathepsin K and cystatin C in patients with cancer related bone disease: Clinical and therapeutic implications

The clinical significance of serum cathepsin K and cystatin C was assessed in patients with breast cancer (BCa) or prostate cancer (PCa) with confined disease (M0) or bone metastasis (BM). Cathepsin K and cystatin C circulating levels were determined by ELISAs in 63 cancer patients, in 35 patients with nonmalignant diseases and in 42 healthy blood donors (control group). In BCa patients, cathepsin K serum levels were sig- nificantly lower than in sex matched control group (HS; p ¼ 0.0008) or in patients with primary osteoporosis (OP; p ¼ 0.0009). On the contrary, cystatin C levels were significantly higher in BCa patients than in HS ( p ¼ 0.0001) or OP ( p ¼ 0.017). In PCa patients, cathepsin K concen- trations did not significantly differ from those measured in sex matched HS or in patients with benign prostatic hyperplasia (BPH). Conversely, cystatin C was more elevated in cancer patients than in controls ( p ¼ 0.0001) or BPH patients ( p ¼ 0.0078). Furthermore, in PCa patients, a pos- itive correlation was observed between cystatin C and cathepsin K (rS ¼ 0.34; p ¼ 0.047). No further relationship was highlighted between these molecules and the clinicobiological parameters of BCa or PCa progression including the number of bone lesions. Moreover, ROC curve analysis showed a poor diagnostic performance of cathepsin K and cystatin C in the detection of BM patients. Interestingly, the administration of zole- dronic acid (ZA), a bisphosphonate derivative endowed with a potent antiosteoclastic activity, induced in BM patients a marked increase of cathepsin K and cystatin C serum levels compared to baseline values. However, this phenomenon was statistically significant only in the PCa group. In conclusion Cystatin C and cathepsin K may be regarded as possible markers to monitor the therapeutic response to bisphosphonate treatments. Nevertheless, their clinical value as specific gauges of skeletal metastasis remains questionable

Cathepsin L in metastatic bone disease: therapeutic implications

Cathepsin L is a lysosomal cysteine proteinase primarily devoted to the metabolic turnover of intracellular proteins. However, accumulating evidence suggests this endopeptidase may be also implicated in the regulation of other important biological functions including bone resorption in normal and pathological conditions. These findings support the concept that cathepsin L, in concert with other proteolytic enzymes involved in bone remodelling processes, may contribute to facilitate bone metastasis formation. In support of this hypothesis, recent studies indicate that cathepsin L may foster this process by triggering multiple mechanisms which, in part, differ from those of the major cysteine proteinase of osteoclast, namely cathepsin K. Therefore, cathepsin L may be regarded as an additional target in the treatment of patients with metastatic bone disease. This review discusses the clinical and therapeutic implications related to these findings

Activin A circulating levels in patients with bone metastasis from breast or prostate cancer

Recent studies have highlighted that Activin A, a member of the transforming growth factor-beta (TGF-beta) superfamily, may be involved in the regulation of osteoblastic activity and in osteoclast differentiation. Therefore, we have investigated the clinical significance of its circulating levels in patients with bone metastasis. Activin A serum concentrations were determined, by a commercially available enzyme-linked immunosorbent assay kit, in 72 patients with breast cancer (BC) or prostatic cancer (PC) with (BM+) or without (BM-) bone metastases, in 15 female patients with age-related osteoporosis (OP), in 20 patients with benign prostatic hypertrophy (BPH) and in 48 registered healthy blood donors (HS) of both sex (25 female and 23 male). Activin A serum concentrations were significantly increased in BC or PC patients as compared to OP (P < 0.0001) or BPH (P = 0.045), respectively, or to sex matched HS (P < 0.0001). Additionally, these levels resulted more elevated in PC patients as compared to BC patients (P = 0.032). Interestingly, Activin A was significantly higher in BM+ patients than in BM- patients (BC, P = 0.047; PC, P = 0.016). In BC patients, a significant correlation was observed only between Activin A and number of bone metastases (P = 0.0065) while, in PC patients, Activin A levels were strongly correlated with the Gleason score (P = 0.011) or PSA levels (P = 0.0001) and, to a lessen extent, with the number of bone metastases (P = 0.056). Receiver operating characteristic curve (ROC) analysis showed a fair diagnostic accuracy of Activin A to discriminate between BM+ and BM- patients (BC: AUC = 0.71 +/- 0.09, P = 0.03; PC: AUC = 0.73 +/- 0.081, P = 0.005). These findings indicate that Activin A may be implicated in the pathogenesis of bone metastasis. Therefore, this cytokine may be considered a novel potential target for a more selective therapeutic approach in the treatment of skeletal metastasis and may be also useful as additional biochemical marker of metastatic bone disease

Follistatin as potential therapeutic target in prostate cancer

Follistatin is a single-chain glycosylated protein whose primary function consists in binding and neutralizing some members of the transforming growth factor-β superfamily such as activin and bone morphogenic proteins. Emerging evidence indicates that this molecule may also play a role in the malignant progression of several human tumors including prostate cancer. In particular, recent findings suggest that, in this tumor, follistatin may also contribute to the formation of bone metastasis through multiple mechanisms, some of which are not related to its specific activin or bone morphogenic proteins’ inhibitory activity. This review provides insight into the most recent advances in understanding the role of follistatin in the prostate cancer progression and discusses the clinical and therapeutic implications related to these findings

Effects of zoledronic acid on proteinase plasma levels in patients with bone metastases.

Background: The effects of the bisphosphonate derivative zoledronic acid (ZA) on the > circulating levels of matrix metalloproteinase-2 (MMP-2), matrix metallo-proteinases-9 > (MMP-9), cathepsin B (Cath B) and urokinase-type plasminogen activator (uPA) in > patients with bone metastasis (BMTS) and the possible correlation with the symptomatic > response induced by this drug in these patients were evaluated. Patients and Methods: > Proteinase levels were determined by enzyme-linked immunosorbent assay (ELISA) in the > plasma of 30 patients with painful bone metastases from breast or prostate cancer > undergoing multiple treatment with ZA (4 mg i.v., every 4 weeks). Healthy subjects > (HS) of both genders (12 female and 30 male) served as the control group. The > symptomatic response to ZA was assessed by the visual analog scale score (VAS). > Results: The median MMP-2 and MMP-9 pretreatment levels were more elevated in BMTS as > compared to HS (p¡Ü0.0001). Conversely, uPA levels were lower in BMTS p=0.0033; no > significant difference was observed for Cath B. ZA administration was associated with > a symptomatic response (VAS score¡Ü4) in 25/30 patients (83.3%) (p<0.0001). This > phenomenon paralleled a decrease of Cath B and MMP-2 plasma concentrations from > baseline values on week 12 (p=0.05). A similar trend, although not statistically > significant, was also noted for MMP-9 and uPA. However, no direct relationship was > observed between the analgesic effect induced by ZA and changes in the circulating > levels of these enzymes. Conclusion: These data show that ZA administration may > provide relief from bone pain in patients with diffuse skeletal metastases and confirm > a possible implication of cysteine proteinases and matrix metalloproteinases in bone > metastasis formation, but not in the pathogenesis of metastatic bone pain

Effects of Oleuropein on colon cancer progression in vitro. A preliminary report

Introduction. Accumulating evidence highlights that Oleuropein (OLE), one of the main bioactive phenolic compound present in olives, olive oil and olive leaves, appears to exert chemo-preventive effects against several human malignancies including gastrointestinal tumors. As the cellular mechanisms underlying this phenomenon are still not fully elucidated, we have undertaken some in vitro studies to examine the effects of OLE on the growth, adhesion and invasion of HTC116 and SW480 human colon cancer cells and the influence of this molecule on the production of certain proteins that appear to be relevant to cancer progression namely, matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9) and transforming growth factor-β (TGF-β) Methods. The effects of OLE on HTC116 and SW480 colon cancer cells growth, adhesion and invasion were evaluated by i) the colorimetric MTT assay, ii) the fibronectin coated multi-well assay and iii) the Matrigel transwell invasion assay, respectively. The influence of OLE on the rate of MMP-2, MMP-9 and TGF-β secretion by tumor cells during adhesion and invasion were determined by enzyme-linked immunosorbent assay. Results. 1)Exposure of human HCT116 and SW480 cancer cells for 24 or 72h to different concentrations of OLE (10-500 µM) resulted in a dose- and time-dependent inhibition of cell proliferation. The calculated IC50 values were 323.1µM and 186.8µM at 24h and 72h respectively for HCT116 tumor cells and 317.6µM at 24h and 226.8 µM at 72h for SW480 tumor cells. 2) The adhesion of HTC116 tumor cells exposed to non-cytotoxic concentrations of OLE (50-250 µM) up to 4h was reduced by 30% as compared to untreated cells while, a 72h continuous exposure to OLE (10-100 µM) decreased HTC116 cell invasion by 40%. This molecule showed to inhibit also SW480 tumor cell adhesion (-25%) but only at the highest drug concentration (250 µM) while, its effects on SW480 invasion were negligible. 3) The secretion of MMP-2, MMP-9 and TGF-β by OLE-treated HCT116 cells during adhesion experiments was reduced (-39%,-19%,-48% respectively) as compared to unexposed cells while, in invasion experiments, the extracellular release of MMP-2 and MMP-9 resulted increased at 24h (+41% and +23%) and then decreased (~ -25%) after 72h. However, TGF-β secretion was not significantly influenced by drug treatments. Finally, in invasion experiments, MMP-9 and TGF-β secretion by OLE-treated SW480 cells resulted impaired (-32% and-74% respectively) while, MMP-2 levels were only slightly affected ( -10%) Conclusions. These data indicate that OLE might exert its chemo-preventive effects by interfering with some key steps of cancer progression, such as tumor cell proliferation, adhesion and invasion and by modulating the extracellular secretion of proteins that may foster these processes. Further studies to better assess the specific molecular mechanisms underlying these phenomena are warranted by these preliminary observations

On the role of cystatin C in cancer progression

Cystatin C (Cyst C) is an endogenous inhibitor of lysosomal cysteine proteinases, which has been shown to play a role in several normal and pathological processes. Interestingly, a growing number of experimental and clinical studies suggest that this inhibitor also appears to be implicated in the malignant progression of various human tumors. However, the role of Cyst C in malignant diseases is still controversial as these studies have highlighted that this protein may function either as tumor suppressor or tumor promoter. The specific mechanisms underlying these opposing effects at present remain murky and are the subject of many current investigations. On the other hand, a complete knowledge of these mechanisms is of clinical interest in order to develop new, effective antitumor treatments based on the appropriate use of natural and/or synthetic cysteine proteinase inhibitors. This paper discusses the current findings regarding the role of Cyst C in cancer progression and the clinical implications emerging from these studies

Cathepsin L in normal and pathological bone reodeling

Abstract Cathepsin L is a ubiquitous lysosomal cysteine endopeptidase that is mainly involved in the metabolic turnover of intracellular proteins. However, it is now well established that this enzyme may also be implicated in the regulation of other important biological processes includ- ing bone resorption. Therefore, altered expression levels of Cathepsin L may result in disturbances of bone homeo- stasis and, eventually, in the onset of pathological condi- tions associated with altered bone turnover. These observations support the concept that Cathepsin L may be regarded as an additional target for the development of novel therapeutic options for the treatment of patients with bone diseases. This review provides insight into the most recent advances in understanding the role of Cathepsin L in normal and pathological bone remodeling and discusses the potential clinical and therapeutic applications related to these findings