The Expression of Cathepsins in Osteoclast-like Giant Cells of an Anaplastic Thyroid Carcinoma with Tracheal Perforation

Osteoclasts in Tumor Biology: Metastasis and Epithelial-Mesenchymal-Myeloid Transition

Osteoclast is a specialized cell that originates from monocytic lineage, communicates closely with osteoblasts under physiological conditions, participates in bone modeling and re-modeling, contributes to calcium homeostasis and osteoimmunity. In pathological conditions, it is involved in many tumors such as giant cell bone tumor (osteoclastoma), aneurysmal bone cyst, osteosarcoma, and metastatic cancers, and it usually causes local spread and progression of the tumor, working against the host. Since osteoclasts play an active role in primary bone tumors and bone metastases, the use of anti-osteoclastic agents significantly reduces the mortality and morbidity rates of patients by preventing the progression and local spread of tumors. Osteoclasts also accompany undifferentiated carcinomas of many organs, especially pancreas, thyroid, bladder and ovary. Undifferentiated carcinomas rich in osteoclasts have osteoclastoma-like histology. In these organs, osteoclastoma-like histology may accompany epithelial carcinomas, and de novo, benign and borderline tumors. Mature and immature myeloid cells, including osteoclasts, play an active role in the tumor progression in primary and metastatic tumor microenvironment, in epithelial-mesenchymal transition (EMT), mesenchymal-epithelial-transition (MET), and cancer stem cell formation. Additionally, they are the most suitable candidates for cancer cells in cell fusion due to their evolutionary fusion capabilities. Myeloid features and markers (CD163, CD33, CD68 etc.) can be seen in metastatic cancer cells. Consequently, they provide metastatic cancer cells with motility, margination, transmigration, chemotaxis, phagocytosis, angiogenesis, matrix degradation, and resistance to chemotherapy. For these reasons, we think that the concept of Epithelial-Mesencyhmal-Myeloid-Transition (EMMT) will be more accurate than EMT for cancer cells with myeloid properties.

Giants and monsters: Unexpected characters in the story of cancer recurrence

Polyploid giant cancer cells (PGCC) constitute a dangerous subpopulation of cancer cells and are a driving force in cancer recurrence. These unique cells arise from diploid tumor cells in response to stress encountered in the tumor microenvironment or during cancer therapy. PGCC are greatly dedifferentiated, acquire pluripotency, and are able to replicate through a form of asymmetric division called neosis, which results in new populations that are themselves able to differentiate into new cell types or to re-establish tumors. Progeny tend to be more genetically unstable than the founding population due to the dysregulation required to transition through a PGCC state. Therefore, cancers that escape stressors through this mechanism tend to re-emerge with a more aggressive phenotype that is therapy resistant. This review focuses on the clinical significance of PGCC, the need for standardized nomenclature and molecular markers, as well as possible avenues to develop therapies aimed at PGCC and the process of neosis. The biology underlying the development of PGCC including cell cycle checkpoint dysregulation, stress responses, dedifferentiation, stemness and epithelial-mesenchymal transition is discussed.

Cathepsin K: The Action in and Beyond Bone

Cathepsin K (CatK) is one of the most potent proteases in lysosomal cysteine proteases family, of which main function is to mediate bone resorption. Currently, CatK is among the most attractive targets for anti-osteoporosis drug development. Although many pharmaceutical companies are working on the development of selective inhibitors for CatK, there is no FDA approved drug till now. Odanacatib (ODN) developed by Merck & Co. is the only CatK inhibitor candidate which demonstrated high therapeutic efficacy in patients with postmenopausal osteoporosis in Phase III clinical trials. Unfortunately, the development of ODN was finally terminated due to the cardio-cerebrovascular adverse effects. Therefore, it arouses concerns on the undesirable CatK inhibition in non-bone sites. It is known that CatK has far-reaching actions throughout various organs besides bone. Many studies have also demonstrated the involvement of CatK in various diseases beyond the musculoskeletal system. This review not only summarized the functional roles of CatK in bone and beyond bone, but also discussed the potential relevance of the CatK action beyond bone to the adverse effects of inhibiting CatK in non-bone sites.

Expression of Cathepsin K in Skull Base Chordoma

OBJECTIVE

The aim of this study was to explore the association between cathepsin K and the clinical characteristics of skull base chordoma (SBC).

METHODS

This study included 58 paraffin-embedded samples and 85 frozen samples of 94 patients. All clinical data corresponding to these patients were available. Immunohistochemical staining and quantitative real-time polymerase chain reaction were performed. Positive rate of immunohistochemical staining slices and delta cycle threshold value of quantitative real-time polymerase chain reaction represented the cathepsin K expression level in protein and gene level separately.

RESULTS

In protein level, expression level (EL) of invasive tumors was increased compared with noninvasive tumors (P = 0.006), EL of tumors with dura erosion was increased compared with tumors without dura erosion (P = 0.001). Tumors with septa exhibited increased EL compared with tumors without septa (P = 0.001). Tumors with lobulation exhibited increased EL compared with tumors without lobulation (P = 0.000). Higher EL of cathepsin K was associated with reduced progression-free survival (PFS) (P = 0.015). In gene level, tumors with septa showed higher EL than tumors without septa (P = 0.015), and tumors with lobulation showed higher EL than tumors without lobulation (P = 0.049). Cathepsin K EL was an independent risk factor for reduced PFS, and an increased level of cathepsin K in SBC was associated with reduced PFS (P = 0.042).

CONCLUSIONS

Increased cathepsin K expression in SBC was associated with tumor invasion and reduced PFS. The cathepsin K level in SBC also was associated with tumor stage, tumor lobulation, and septa.

Uterine leiomyosarcoma with osteoclast-like giant cells associated with high expression of receptor activator of nuclear factor κB ligand

The occurrence of osteoclast-like giant cells (OLGCs) in uterine leiomyosarcomas (LMSs) is a rare phenomenon. The nature of OLGCs and the significance of their accumulation in these tumors are poorly understood. Recent studies revealed that the formation of osteoclasts requires a specific cytokine, receptor activator of nuclear factor κB ligand (RANKL), in bone. In this study, we investigated the expression of RANKL in 2 cases of uterine LMS with OLGCs by means of immunohistochemistry and compared the extent of RANKL expression with that in conventional uterine LMSs and leiomyomas by using real-time reverse-transcription quantitative polymerase chain reaction. Our cases of uterine LMS with OLGCs showed markedly high expression of RANKL messenger RNA with clear RANKL immunoreactivity compared with messenger RNA expression and immunoreactivity of conventional uterine LMSs and leiomyomas. These findings suggest that the tumors producing RANKL may account for accumulation of OLGCs in tumor tissue because of RANKL-related osteoclastogenesis.

Cathepsin K inhibitors for osteoporosis and potential off-target effects

Cathepsin K is a highly potent collagenase and the predominant papain-like cysteine protease expressed in osteoclasts. Cathepsin K deficiencies in humans and mice have underlined the central role of this protease in bone resorption and, thus, have rendered the enzyme as an attractive target for anti-resorptive osteoporosis therapy. In the past decade, a lot of efforts have been made in developing highly potent, selective and orally applicable cathepsin K inhibitors. Some of these inhibitors have passed preclinical studies and are presently in clinical trials at different stages of advancement. The development of the inhibitors and preliminary results of the clinical trials revealed problems and lessons concerning the in situ specificity of the compounds and their tissue targeting. In this review, we briefly summarize the history of cathepsin K research and discuss the current development of cathepsin K inhibitors as novel anti-resorptives for the treatment of osteoporosis. We also discuss potential off-target effects of cathepsin K inhibition and alternative applications of cathepsin K inhibitors in arthritis, atherosclerosis, blood pressure regulation, obesity and cancer.

Biochemistry and Clinical Role of Human Cystatin C

Low molecular-mass plasma proteins play a key role in health and disease. Cystatin C is an endogenous cysteine proteinase inhibitor belonging to the type 2 cystatin superfamily. The mature, active form of human cystatin C is a single non-glycosylated polypeptide chain consisting of 120 amino acid residues, with a molecular mass of 13,343-13,359 Da, and containing four characteristic disulfide-paired cysteine residues. Human cystatin C is encoded by the CST3 gene, ubiquitously expressed at moderate levels. Cystatin C monomer is present in all human body fluids; it is preferentially abundant in cerebrospinal fluid, seminal plasma, and milk. Cystatin C L68Q variant is an amyloid fibril-forming protein with a high tendency to dimerize. It forms self-aggregates with massive amyloid deposits in the brain arteries of young adults, leading to lethal cerebral hemorrhage. The main catabolic site of cystatin C is the kidney: more than 99% of the protein is cleared from the circulation by glomerular ultrafiltration and tubular reabsorption. The diagnostic value of cystatin C as a marker of kidney dysfunction has been extensively investigated in multiple clinical studies on adults, children, and in the elderly. In almost all the clinical studies, cystatin C demonstrated a better diagnostic accuracy than serum creatinine in discriminating normal from impaired kidney function, but controversial results have been obtained by comparing this protein with other indices of kidney disease, especially serum creatinine-based equations. In this review, we present and discuss most of the available data from the literature, critically reviewing conclusions and suggestions for the use of cystatin C in clinical practice. Despite the multitude of clinical data in the literature, cystatin C has not been widely used, perhaps because of a combination of factors, such as a general diffidence among clinicians, the absence of definitive cut-off values, conflicting results in clinical studies, no clear evidence on when and how to request the test, the poor commutability of results, and no accurate examination of costs and of its routine use in a stat laboratory.

Oesophageal and tracheal perforation in thyroid B-cell lymphoma

We report an unusual case of spontaneous oesophageal and tracheal perforation secondary to thyroid B-cell lymphoma in a previously healthy 76-year-old woman. Findings on chest radiography, CT and oesophagram are correlated to endoscopy, surgery and pathology. Such perforation is a rare and serious complication that should be specifically considered when a patient with a neck neoplasm develops acute respiratory or gastrointestinal symptoms.

Biochemical properties and regulation of cathepsin K activity

Cysteine cathepsins (11 in humans) are mostly located in the acidic compartments of cells. They have been known for decades to be involved in intracellular protein degradation as housekeeping proteases. However, the discovery of new cathepsins, including cathepsins K, V and F, has provided strong evidence that they also participate in specific biological events. This review focuses on the current knowledge of cathepsin K, the major bone cysteine protease, which is a drug target of clinical interest. Nevertheless, we will not discuss recent developments in cathepsin K inhibitor design since they have been extensively detailed elsewhere. We will cover features of cathepsin K structure, cellular and tissue distribution, substrate specificity, and regulation (pH, propeptide, glycosaminoglycans, oxidants), and its putative roles in physiological or pathophysiological processes. Finally, we will review the kinetic data of its inhibition by natural endogenous inhibitors (stefin B, cystatin C, H- and L-kininogens).

Cytology of anaplastic giant cell carcinoma of the thyroid with osteoclast-like giant cells--a case report

Anaplastic carcinoma of the thyroid is known for its highly aggressive behaviour and rapid spread. While the giant cell variant is a well recognized morphologic pattern, the presence of osteoclast-like giant cells is a rare occurrence. We report a case of anaplastic carcinoma of the thyroid with focal presence of osteoclast-like giant cells occurring in an elderly male patient, diagnosed on aspiration cytology.

Cysteine proteinase inhibitor cystatin C in squamous cell carcinoma of the head and neck: relation to prognosis

To determine the role of the cysteine proteinase inhibitor cystatin C in the invasive behavior of squamous cell carcinoma of the head and neck (SCCHN), Cystatin C protein level was measured in 82 pairs of primary tumour tissue and adjacent noncancerous mucosa, using the enzyme-linked immunosorbent assay. The median level of cystatin C in tumour tissue was 1.18 times lower than that in corresponding mucosa (P=0.031). In normal mucosa samples, the cystatin C level was influenced by the site of sampling: it was lower in nonlaryngeal tissue samples (oral cavity, oro- or hypopharynx) than in laryngeal samples (P=0.004). The tumour cystatin C level correlated inversely with pN-stage (P=0.047), whereas a trend of lower cystatin C levels was observed in the group with extranodal tumour extension compared to those with no extranodal spread (P=0.069). In univariate analysis, the patients with low tumour cystatin C levels exhibited poor disease-free survival (DFS, P=0.013) and disease-specific survival (DSS, P=0.013). In multivariate analysis, the most powerful predictor of survival was pN-stage (DFS: P=0.040, HR 2.78; DSS: P=0.011, HR 4.36,), followed by the cystatin C level (DFS: P=0.043, HR 0.22; DSS: P=0.067, HR 0.25). When comparing the prognostic strength of cystatin C to that of stefin A, another cysteine proteinase inhibitor, which emerged as the most significant prognosticator for survival in our previous study analysing the same cohort of patients, stefin A proved to be significantly more reliable predictor for both DFS and DSS than cystatin C. Our results indicate that cystatin C is implicated in the invasive behavior of SCCHN, and that there are variations in regulation of proteolytic pathways under nonmalignant conditions, inherent to individual subsites inside the upper aerodigestive tract. The correlation between high cystatin C levels and improved survival concurs with the concept of the protective role of high levels of cysteine proteinase inhibitors in tissue homogenates that has been previously suggested by the survival results in breast and lung carcinoma as well as SCCHN.

Identification of cathepsin K as a novel marker of adiposity in white adipose tissue

In obesity, adipocytes undergo dramatic morphological and molecular changes associated with alterations in their gene expression profile. To identify genes differentially modulated in white adipose tissue (WAT) of obese db/db mice compared to wild type (wt) mice, we utilized RNA fingerprinting. Among the 52 candidates that we identified, we focused here on cathepsin K (ctsk), a cysteine protease, prevalently localized in lysosomes and involved in bone extracellular matrix degradation. In db/db mice, WAT ctsk mRNA was elevated 5.9-fold, as were Mitf and TFE3 (2- and 3.3-fold respectively), two transcription factors involved in ctsk induction in osteoclasts. Moreover, the level of WAT ctsk mRNA was increased in other obese models including A(y), fat, and tubby (2.8-, 3.2-, and 4.9-fold respectively) and decreased in mice undergoing weight loss. Despite the ubiquitous distribution of the ctsk transcript, we demonstrated that the obesity related increase is specific to the adipocytes. Further, in vitro experiments proved that the abundance of ctsk transcript increases upon adipose conversion of the established cell line of preadipocytes 3T3-F442A. In addition, ctsk gene expression was examined in adipose tissue of 21 lean and obese male subjects and significant correlations with BMI (r = 0.54, P = 0.012) and plasma leptin levels (r = 0.54, P = 0.015) were found. In conclusion, the WAT of obese db/db mice exhibits a different expression profile from that of the wt mice, and cathepsin K can be considered a novel marker of obesity and a target for the inhibition of adipose mass growth.

Modulation of cystatin C expression impairs the invasive and tumorigenic potential of human glioblastoma cells

Increases in the abundance of cathepsin B transcript and protein with increased tumor grade and changes in subcellular localization and activity of this enzyme. We observed progressive reductions in levels of the protease inhibitor cystatin C, an inhibitor of cathepsin B with corresponding increases in the malignancy of glioma cell lines, implying an inverse correlation between cystatin C and tumor grade. To investigate the role of cystatin C in the invasion of brain tumor cells, we stably transfected SNB19 glioblastoma cells with either a 0.4-kb cDNA construct of human cystatin C in the sense orientation or an empty vector. Clones expressing sense-cystatin C cDNA had higher cystatin C mRNA and protein levels than did control cells. Sense-transfected cells were also markedly less invasive than control cells in a Matrigel invasion assay and in a coculture assay of SNB19 spheroids and fetal rat brain aggregates. Finally, the sense-transfected cells did not form tumors in nude mice upon intracerebral injection. These results strongly implicate cystatin C in the invasiveness of human glioblastoma cells and suggest that sense transcripts of cystatin C may prove useful in cancer therapy.