Disease relevance of CSTA

• The relationship of cathepsin B and stefin A mRNA localization identifies a potentially aggressive variant of human prostate cancer within a Gleason histologic score [1].
• Transfection of the dominant-negative form of ERK adenovirus (Ad-dnERK) increased cystatin A promoter activity and its expression, which was markedly augmented by 1,25(OH)(2)D3 treatment [2].
• The ratios of CB to stefin A were similar in normal prostate and benign prostatic hyperplasia (BPH) whereas they varied consistently within and between Gleason histologic scores for prostate cancer [1].
• EXPERIMENTAL DESIGN: We stably transfected stefin A cDNA into human EC9706 or KYSE150 esophageal squamous cell carcinoma cells [3].
• Overexpression of stefin A delayed the in vitro and in vivo growth of cells and significantly inhibited lung metastasis compared with 50% of lung metastasis in xenograft mice from EC9706 or empty vector cells [3].
• We conclude that Stefin A expression reduces distant metastasis in breast cancer and propose that this may be due to the inhibition of cysteine cathepsins, such as cathepsin B [4].

High impact information on CSTA

• Although the interface between cystatin-fold units is poorly defined for cystatin A, the dimers are the appropriate size to account for the electron-dense regions in amyloid protofilaments [5].
• Cystatin A (acid cysteine proteinase inhibitor; ACPI) is a natural inhibitor of cysteine proteinases [6].
• After adjusting for the effect of tumor size, histological grade, and lymph node status, cystatin A-positive patients still had a higher risk of death [6].
• Cysteine proteinase inhibitor cystatin A in breast cancer [6].
• The Ki values for inhibition by leupeptin and stefin A were 20-fold higher [7].

Chemical compound and disease context of CSTA

• Cysteine proteinase inhibitors stefin A, stefin B, and cystatin C in sera from patients with colorectal cancer: relation to prognosis [8].
• Formalin-fixed and paraffin embedded specimens from normal skin, seborrheic keratoses, and squamous cell carcinomas were reacted with polyclonal antibodies against rat cathepsin L or cystatin a which cross-react to human cathepsin L and cystatin A, respectively [9].
• Fourier transform ion cyclotron resonance mass spectra of 13C,15N-doubly depleted cystatin A M65L, produced by Escherichia coli grown on 99.9% [12C]glucose and 99.99% [14N]ammonium sulfate, showed salient monoisotopic peaks composed of 12C and 14N [10].
• The amounts of the epidermal proteins filaggrin, involucrin, cystatin A and Ted-H-1 antigen produced during the terminal differentiation of keratinocytes were immunohistochemically measured in lesional and nonlesional skin of atopic dermatitis (AD) patients [11].

Biological context of CSTA

• Crystal structure of Stefin A in complex with cathepsin H: N-terminal residues of inhibitors can adapt to the active sites of endo- and exopeptidases [12].
• The kinetics of binding to papain were consistent with a simple reversible bimolecular reaction mechanism, indicating that cystatin A, like chicken cystatin and cystatin C, binds to papain with no appreciable conformational adaptation of either reacting protein [13].
• Amino acid sequence determination revealed the presence of stefin A and stefin B type inhibitors and two new inhibitors, designated as porcine stefin D1 and stefin D2 [14].
• Overexpression of stefin A in human esophageal squamous cell carcinoma cells inhibits tumor cell growth, angiogenesis, invasion, and metastasis [3].
• We continuously measured cardiac output (Qt) and pulmonary artery, left atrial, airway, and pleural pressures and intermittently measured arterial and mixed venous blood gas tensions and static and dynamic compliance (CSTA, CDYN) with an 18 ml/kg test inflation [15].

Anatomical context of CSTA

• Co-transfection of the cystatin A promoter into normal human keratinocytes together with a dominant active form of ras increased the promoter activity by 3-fold [16].
• Stefin A was expressed on the surface of the trophoblast [17].
• Cystatin A is expressed in squamous epithelia, neutrophil granulocytes, and dendritic reticulum cells of the lymphatic tissues [18].
• Immunohistochemical staining of cathepsins B, L and stefin A in human hypophysis and pituitary adenomas [19].
• All cases with intact mucous membrane of the middle ear exhibited no expression of cystatin A. Seven of 10 cases with diseased tissues expressed cystatin A in cholesteatoma epithelium, granulation tissues in cholesteatoma, or granulation tissues in noncholesteatoma [20].

Associations of CSTA with chemical compounds

• Cystatin A, a cysteine proteinase inhibitor, is a cornified cell envelope constituent expressed in the upper epidermis [16].
• The near-UV spectroscopic changes induced by the binding of recombinant human cystatin A to papain were appreciably different from those induced by cystatin C, reflecting mainly interactions involving the single tryptophan of cystatin C, Trp-106 [13].
• Cystatin A promoter activity was not affected by cotransfection of vitamin D(3) receptor or retinoid X receptor [2].
• Similar rates of refolding (6.2s-1 and 7.2 s-1 for ellipticity at 230 and 280 nm, respectively) were observed for stefin A denatured in 66% (vol/vol) TFE, pH 3.3, when refolding to the same final conditions [21].
• This finding is in agreement with previous conclusions that glycine in this position is essential for tight binding of cystatin A to cysteine proteinases by allowing optimal interaction of the N-terminal region of the inhibitor with the enzyme [22].

Physical interactions of CSTA

• Cystatin A bound tightly and rapidly to papain and cathepsin L, with dissociation equilibrium constants of approximately 10(-11)-10(-13) M and association rate constants of 3 x 10(6)-5 x 10(6) M-1.s-1 [13].
• Comparison with the X-ray structure of cystatin B in the papain complex shows that the conformation of the first binding loop is quite similar to that of cystatin A, with an rms deviation of 0.78 A for the backbone atoms in the 43-53 region (cystatin A numbering) [23].
• The principal difference is the presence of two conformationally unrestricted regions in stefin A that form two of the components of the tripartite wedge which docks into the active site of the target proteinase [24].

Regulatory relationships of CSTA

• Transfection of the dominant-active form of Raf-1 (Ad-daRaf-1) or MEK1 (Ad-daMEK1) inhibited 1,25(OH)(2)D3-dependent cystatin A promoter activity and its expression [2].
• Stefin A inhibited cathepsin F slowly (kass=1.6 x 10(5) M(-1) s(-1)) and with a lower affinity (Ki=25 nM) [25].

Other interactions of CSTA

• We previously reported that a potent protein kinase C activator, 12-O-tetradecanoylphorbol-13-acetate, increases human cystatin A expression by the activation of AP-1 proteins [16].
• The approach of stefin A to cathepsin H induces structural changes along the interaction surface of both molecules, whereas no such changes were observed in the stefin B-papain complex [12].
• The latter finding indicates that the intact N-terminal region serves as a guide directing cystatin A to the active site of cathepsin B, as has been proposed for cystatin C [26].
• Stefin A is composed of 101 amino acids and has an Mr of 11 391 while stefin B contains 98 amino acids, has an Mr of 11 174 and is N-terminally blocked [14].
• Consistent with these results, the MEK1 inhibitor, PD98059, further augmented 1,25(OH)(2)D3-induced cystatin A promoter activity and its expression [2].

Analytical, diagnostic and therapeutic context of CSTA

• The importance of the evolutionarily conserved Gly-4 residue for the affinity and kinetics of interaction of cystatin A with several cysteine proteinases was assessed by site-directed mutagenesis [26].
• Transfection with stefin A showed a dramatic reduction of factor VIII staining in the tumors of xenograft mice [3].
• Cystatin A expressions were observed by Western blot analysis [20].
• The endogenous inhibitors of cysteine proteinases, cystatin A and cystatin B, have been localized in sections of human liver by indirect immunofluorescence microscopy [27].
• The opposite was true for stefin A (p = 0.0002; p = 0.002) and stefin B (p = 0.009; p = 0.003), and in disease-free survival also for cathepsin H (p = 0.055) [28].

References