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Biomedical subjects

Gary L Clayman

Publications and source records attributed to Gary L Clayman.

At least 37 records · Page 2Linked to original sources
PubMed2005

Mortality risk from squamous cell skin cancer.

PURPOSE: To identify nonmelanoma skin cancer patients with squamous cell carcinoma (SCC) who are at greatest risk of disease-specific mortality. PATIENTS AND METHODS: Prospectively enrolled patients with a minimum of one pathologically confirmed skin SCC lesion, definitive treatment of the SCC lesion(s) resulting in no evidence of disease, and at least 2 months of follow-up after definitive treatment were eligible for the present longitudinal analysis. They received comprehensive clinical, pathologic evaluations and follow-up for patterns of failure and mortality. RESULTS: We enrolled 210 patients (187 men and 23 women) with a total of 277 skin SCC lesions and a median enrollment age of 68 years (range, 34 to 95 years). Median follow-up of surviving patients was 22 months. Three-year overall and disease-specific survival (DSS) rates were 70% and 85%, respectively. In univariate analyses, the clinical-pathologic factors associated with adverse DSS were local recurrence at presentation (P = .05), invasion beyond subcutaneous tissues (P = .009), perineural invasion (P = .002), lesion size (P = .0003), and depth of invasion (P = .05). Statistical models identified a homogeneous high-risk group of patients with lesions > or = 4 cm, perineural invasion, and deep invasion beyond subcutaneous structures. Three-year DSS was 100% for patients with no risk factors versus 70% for patients with at least one risk factor. CONCLUSION: Lesion size > or = 4 cm and histologic evidence of perineural invasion and deep invasion beyond subcutaneous structures were the clinical-pathologic factors most significantly associated with disease-specific mortality in skin SCC.

Adult↗
PubMed2005

Lymph node metastases from cutaneous squamous cell carcinoma of the head and neck.

OBJECTIVE/HYPOTHESIS: Cutaneous squamous cell carcinoma (CSCC) has been reported to metastasize to parotid and cervical lymph nodes. Few prospective investigations of associated clinical and histopathologic findings and their effect on patient outcomes exist. We seek to identify risk factors for nodal metastases in CSCC and determine the impact of lymphatic spread on survival and recurrence. STUDY DESIGN: Subset analysis of a prospective, longitudinal database of patients with CSCC at a comprehensive cancer center. METHODS: Eligible patients with nonmelanoma skin cancer were consecutively enrolled in a prospective database from July 1996 through June 2001; this cohort was then followed to the key endpoints of recurrence and mortality. RESULTS: Two hundred ten patients were enrolled, and 193 patients with CSCC of the head and neck are included in this analysis. The incidence of nodal metastases in this population was 20.7% at study entry. Median follow-up was 20 months in patients with lymph node metastases and 24 months in patients without metastases. Nodal metastases were significantly associated with recurrent lesions (P = .002) and the following histopathologic features: lymphovascular invasion (P < .0001), inflammation (P = .010), poorly differentiated histology (P = .001), invasion into the subcutaneous tissues (P = .0001), perineural invasion (P = .005), and larger size (P = .0007). Metastases to the cervical nodes were not clinically apparent in 42% of patients with parotid metastases. Combination surgery and radiation therapy resulted in regional control rates of 95%, although local recurrence and distant metastases, along with second primary tumors, were the most frequent recurrent events. Kaplan-Meier survival analysis demonstrates a decrease in overall survival (P = .005), disease-free survival (P = .015), disease-specific survival (P = 0002), and time to recurrence (P = .012) in patients with nodal metastases compared with controls. CONCLUSIONS: Lymph node metastases from CSCC are common in our population and are associated with diminished survival. The presence of nodal spread occurs with other adverse histopathologic findings, and we recommend surgery and postoperative radiation therapy to control regional disease in the presence of nodal metastases and perineural invasion. New approaches in early identification of nodal metastases, treatment, and prevention of local recurrences and second primary malignancies are warranted.

Adult↗
PubMed2005

Treatment considerations for head and neck cancer in the elderly.

As life expectancy increases, surgeons can expect an increasing number of geriatric patients. In turn, the number of elderly patients presenting with head and neck cancer is likely to increase. Management of this subpopulation has become a source of debate because there is a paucity of randomized data regarding the effect of age on treatment response and morbidity associated with the treatment of head and neck cancer. The management of head and neck cancer in the elderly depends on the patient's age and general condition, the stage of disease, the effects of treatment on quality of life (such as speech and swallowing), patient and family wishes, and active physician participation in continued care. Elderly patient's comorbid conditions need appropriate attention especially if surgery is to be undertaken. The aim of this review is to examine the current literature in an attempt to develop an approach to the treatment of the elderly patient with head and neck cancer and to define the pertinent issues that require further study.

Age Factors↗
PubMed2005

Inhibition of human kallikreins 5 and 7 by the serine protease inhibitor lympho-epithelial Kazal-type inhibitor (LEKTI).

LEKTI is a 120-kDa protein that plays an important role in skin development, as mutations affecting LEKTI synthesis underlie Netherton syndrome, an inherited skin disorder producing severe scaling. Its primary sequence indicates that the protein consists of 15 domains, all resembling a Kazal-type serine protease inhibitor. LEKTI and two serine proteases belonging to the human tissue kallikrein (hK) family (hK5 and hK7) are expressed in the granular layer of skin. In this study, we characterize the interaction of two recombinant LEKTI fragments containing three or four intact Kazal domains (domains 6-8 and 9-12) with recombinant rhK5, a trypsin-like protease, and recombinant rhK7, a chymotrypsin-like protease. Both fragments inhibited rhK5 similarly in binding and kinetic studies performed at pH 8.0, as well as pH 5.0, the pH of the stratum corneum where both LEKTI and proteases may function. Inhibition equilibrium constants (Ki) measured either directly in concentration-dependent studies or calculated from measured association (kass) and dissociation (kdis) rate constants were 1.2-5.5 nM at pH 8.0 and 10-20 nM at pH 5.0. At pH 8.0, kass and kdis values were 4.7 x 10(5) M(-1) s(-1) and 5.5 x 10(-4) s(-1), and at pH 5.0 they were 4.0 x 10(4) M(-1) s(-1) and 4.3 x 10(-4) s(-1), respectively. The low Ki and kdis values (t1/2 of 20-25 min) indicate tight and specific association. Only fragment 6-9' was a good inhibitor of rhK7, demonstrating a Ki of 11 nM at pH 8.0 in a reaction that was rapidly reversible. These results show that LEKTI, at least in fragment form, is a potent inhibitor of rhK5 and that this protease may be a target of LEKTI in human skin.

Carrier Proteins↗
PubMed2004

Sinonasal malignancies with neuroendocrine differentiation: patterns of failure according to histologic phenotype.

BACKGROUND: Sinonasal neuroendocrine tumors are rare malignancies that are represented by a spectrum of histologies, including esthesioneuroblastoma (ENB), sinonasal undifferentiated carcinoma (SNUC), neuroendocrine carcinoma (NEC), and small cell carcinoma (SmCC). The authors reviewed their institutional experience to determine whether sinonasal neuroendocrine tumors of different histologies have distinct clinical characteristics that warrant individualized treatment approaches. METHODS: The authors treated 72 adults with pathologically proven, nonmetastatic, primary sinonasal neuroendocrine tumors from 1982 to 2002. There were 31 patients with ENB, 16 patients with SNUC, 18 patients with NEC, and 7 patients with SmCC. Patients with ENB usually were treated with local therapy alone (surgery and/or radiotherapy); only 3 of 31 patients (9.7%) received treatment (radiation) to regional lymphatics, and only 5 of 31 patients (16.1%) received chemotherapy. In contrast, patients with non-ENB histologies usually received chemotherapy (10 of 16 patients with SNUC, 12 of 18 patients with NEC, and 5 of 7 patients with SmCC), and nonsurgical locoregional therapy was used more frequently (6 of 16 patients with SNUC, 4 of 18 patients with NEC, and 5 of 7 patients with SmCC). RESULTS: The median follow-up for surviving patients was 81.5 months (range, 6-266 months). The Kaplan-Meier estimate of overall survival at 5 years was 93.1% for patients with ENB, 62.5% for patients with SNUC, 64.2% for patients with NEC, and 28.6% for patients with SmCC (P = 0.0029; log-rank test). The local control rate at 5 years also was superior for patients who had ENB (96.2%) compared with patients who had SNUC (78.6%), NEC (72.6%), or SmCC (66.7%) (P = 0.04). The regional failure (RF) rate at 5 years was 8.7% for patients with ENB, 15.6% for patients with SNUC, 12.9% for patients with NEC, and 44.4% for patients with SmCC. Additional late events increased the RF rate for patients with ENB to 31.9% at 10 years. The distant metastasis rate at 5 years was 0.0% for patients with ENB, 25.4% for patients with SNUC, 14.1% for patients with NEC, and 75.0% for patients with SmCC. CONCLUSIONS: This spectrum of malignancies with neuroendocrine features shares a common site of origin within the head and neck, but their natural histories appear to diverge into two main groups: ENB and non-ENB. Patients with ENB had excellent local and distant control rates with local therapy alone. Given the higher rates of systemic failure for patients with SNUC, NEC, and SmCC, the authors favor the use of combined-modality therapy for these patients.

Adolescent↗
PubMed2004

BRAK/CXCL14 is a potent inhibitor of angiogenesis and a chemotactic factor for immature dendritic cells.

BRAK/CXCL14 is a CXC chemokine constitutively expressed at the mRNA level in certain normal tissues but absent from many established tumor cell lines and human cancers. Although multiple investigators cloned BRAK, little is known regarding the physiologic function of BRAK or the reason for decreased expression in cancer. To understand the possible significance associated with loss of BRAK mRNA in tumors, we examined the pattern of BRAK protein expression in normal and tumor specimens from patients with squamous cell carcinoma (SCC) of the tongue and used recombinant BRAK (rBRAK) to investigate potential biological functions. Using a peptide-specific antiserum, abundant expression of BRAK protein was found in suprabasal layers of normal tongue mucosa but consistently was absent in tongue SCC. Consistent with previous in situ mRNA studies, BRAK protein also was expressed strongly by stromal cells adjacent to tumors. In the rat corneal micropocket assay, BRAK was a potent inhibitor of in vivo angiogenesis stimulated by multiple angiogenic factors, including interleukin 8, basic fibroblast growth factor, and vascular endothelial growth factor. In vitro, rBRAK blocked endothelial cell chemotaxis at concentrations as low as 1 nmol/L, suggesting this was a major mechanism for angiogenesis inhibition. Although only low affinity receptors for BRAK could be found on endothelial cells, human immature monocyte-derived dendritic cells (iDCs) bound rBRAK with high affinity (i.e., K(d), approximately 2 nmol/L). Furthermore, rBRAK was chemotactic for iDCs at concentrations ranging from 1 to 10 nmol/L. Our findings support a hypothesis that loss of BRAK expression from tumors may facilitate neovascularization and possibly contributes to immunologic escape.

Carcinoma, Squamous Cell↗
PubMed2004

Gene expression profiling of differentiated thyroid neoplasms: diagnostic and clinical implications.

PURPOSE: The purpose of this research was to identify novel genes that can be targeted as diagnostic and clinical markers of differentiated thyroid tumors. EXPERIMENTAL DESIGN: Gene expression analysis using microarray platform was performed on 6 pathologically normal thyroid samples and 12 primary follicular and papillary thyroid neoplasms. Microarrays containing probes for 5,760 human full-length cDNAs were used for hybridization with total RNA from normal and tumor thyroid samples labeled with Cy3-dUTP and Cy5-dUTP, respectively. Scanned array images were recorded, and data analysis was performed. Selected sets of differentially expressed genes were analyzed using quantitative real-time reverse transcription-PCR for verification. RESULTS: We identified 155 genes that differentiate histologically normal thyroid tissues from benign and malignant thyroid neoplasms. Of these 75 genes were differentiated between follicular neoplasms (adenoma and carcinoma) and the follicular variant of papillary carcinoma. Purely follicular neoplasms (adenomas and carcinomas) shared many genetic profiles, and only 43 genes were distinctly different between these tumors. Hierarchical cluster analysis also differentiated conventional papillary carcinoma from its follicular variant and follicular tumors. The differentially expressed genes were composed of members of cell differentiation, adhesion, immune response, and proliferation associated pathways. Quantitative real-time reverse transcription-PCR analysis of selected genes corroborated the microarray expression results. CONCLUSIONS: Our study show the following: (1) differences in gene expression between tumor and nontumor bearing normal thyroid tissue can be identified, (2) a set of genes differentiate follicular neoplasm from follicular variant of papillary carcinoma, (3) follicular adenoma and carcinoma share many of the differentiated genes, and (4) gene expression differences identify conventional papillary carcinoma from the follicular variant.

Adenocarcinoma, Follicular↗
PubMed2004

The effect of cyclin D1 overexpression in human head and neck cancer cells.

Overexpression of cyclin D1 in head and neck cancer has been suggested to be a poor prognostic factor. To understand the role of cyclin D1 expression in head and neck cancer, we overexpressed cyclin D1 in TU182 (a cell line derived from pharyngeal cancer) using a retroviral vector. Stable transfectants were isolated by neomycin (G418) selection. Compared to the parental and control-vector transfected cells, the cyclin D1 transfected cells revealed a decrease of the G1/G0 population and resulted in continuous proliferation under low serum conditions. Proliferation assays revealed an increase in resistance to cisplatin in cyclin D1 overexpressing cells. These observation suggest that deregulation of cyclin D1 may reduce growth factor requirements and contribute to the resistance to some chemotherapeutic agents among head and neck cancer patients.

Antineoplastic Agents↗
PubMed2004

Parathyroid carcinoma: evaluation and interdisciplinary management.

BACKGROUND: A review of recent reports found a distinct clinical behavior pattern in the rare clinical entity of parathyroid carcinoma, although to the authors' knowledge information on oncogenetic changes, prognostic factors, and the potential benefits of adjuvant therapy remain fragmented and scarce. In this report, a composite review of the literature and The University of Texas M. D. Anderson Cancer Center (M. D. Anderson) experience are presented using the presentation of a patient to illustrate critical issues in the evaluation and interdisciplinary management of patients who are afflicted with this disease. METHODS: The current study reflects a retrospective case review of patients who were diagnosed with parathyroid carcinoma, treated, and followed at M. D. Anderson from 1983 to 2002. To assure standardization of pathologic diagnosis as well as evaluations and interdisciplinary management, the investigators reviewed all cases using predetermined criteria within their specialties. RESULTS: It is interesting to note that M. D. Anderson data showed classic pathologic features that were not always present in all parathyroid carcinomas (at most, some features were noted in 37% of patients). Other results of interest indicated local recurrence rates that appeared lower if adjuvant radiation was applied after initial surgery, independent of the type of surgery or disease stage. In the authors' experience, 70% of patient's tumors exhibited local invasion, although their 5-year survival rate of 85% was consistent with that reported previously, and their 10-year survival rate was somewhat higher at 77%. CONCLUSIONS: Parathyroid carcinoma is a rare clinical entity that requires interdisciplinary evaluation and management. Comprehensive surgical excision of parathyroid carcinomas with verification of normalization of intraoperative parathyroid hormone levels should be sought.

Adult↗
PubMed2004

The epidermal growth factor receptor tyrosine kinase inhibitor ZD1839 (Iressa) suppresses c-Src and Pak1 pathways and invasiveness of human cancer cells.

PURPOSE: Abnormalities in the expression and signaling pathways downstream of the epidermal growth factor receptor (EGFR) contribute to the progression, invasion, and maintenance of the malignant phenotype in human cancers, including those of the head and neck and breast. Accordingly, agents such as the EGFR tyrosine kinase inhibitor (EGFR-TKI) ZD1839 (Iressa) are promising, biologically based treatments that are in various stages of preclinical and clinical development. The process of tumor progression requires, among other steps, increased transformation, directional migration, and enhanced cell survival; this study explored the effect of ZD1839 on the stimulation of c-Src and p21-activated kinase 1 (Pak1), which are vital for transformation, directional motility, and cell survival of cancer cells. EXPERIMENTAL DESIGN: We examined the effect of ZD1839 on biochemical and functional assays indicative of directional motility and cell survival, using human head and neck squamous cancer cells and breast cancer cells. RESULTS: ZD1839 effectively inhibited c-Src activation and Pak1 activity in exponentially growing cancer cells. In addition, ZD1839 suppressed EGF-induced stimulation of EGFR autophosphorylation on Y1086 and Grb2-binding Y1068 sites, c-Src phosphorylation on Y215, and Pak1 activity. ZD1839 also blocked EGF-induced cytoskeleton remodeling, redistribution of activated EGFR, and in vitro invasiveness of cancer cells. CONCLUSIONS: These studies suggest that the EGFR-TKI ZD1839 may cause potent inhibition of the Pak1 and c-Src pathways and, therefore, have potential to affect the invasiveness of human cancer cells deregulated in these growth factor receptor pathways.

Antineoplastic Agents↗
PubMed2004

Parathyroid carcinoma: a 22-year experience.

PURPOSE: Because parathyroid carcinoma is rare, clear consensus is not available regarding the optimal management of patients with this condition. Treatment strategies generally derive from clinical and anecdotal experiences. We report our experience with this entity. METHODS: We included all patients with parathyroid carcinoma seen at The University of Texas M. D. Anderson Cancer Center since January 1, 1980. The medical records and pathology specimens were reviewed and verified in all cases. RESULTS: Since 1980, 27 patients (16 men and 11 women) registered at M. D. Anderson Cancer Center with parathyroid carcinoma and a minimum follow-up of 2 years. The age at initial diagnosis (mean +/- SD) was 46.7 +/- 15.3 years. All patients were seen with hypercalcemia (mean calcium, 13.4 +/- 1.5 mg/dL). Eighteen patients had locally invasive disease, eight had localized disease, and one had distant metastasis. Parathyroid cancer was treated with complete surgical excision with curative intent in 18 patients. In the other nine patients, who had clinical and/or radiographic evidence of soft tissue extension, the tumor was treated by comprehensive "en bloc" soft tissue resection. Of six patients who received adjuvant radiotherapy after initial surgery, only one had a local relapse. In contrast, of 20 patients who did not receive adjuvant radiotherapy, 10 had a local relapse, excluding the one patient who had distant metastases. The 5-year survival was 85%, and the 10-year survival was 77%. Five patients died of parathyroid carcinoma; all deaths were hypercalcemia related. CONCLUSIONS: Parathyroid carcinoma can be an indolent disease with morbidity and mortality related to hypercalcemia. Adjuvant radiotherapy may improve local control and limit the occurrence of local relapse. A comprehensive multidisciplinary approach with surgery, radiation therapy, and medical treatment for hypercalcemia is needed to optimize patient outcome.

Adolescent↗
PubMed2004

Expression of LEKTI domains 6-9' in the baculovirus expression system: recombinant LEKTI domains 6-9' inhibit trypsin and subtilisin A.

The precursor lympho-epithelial Kazal-type-related inhibitor (LEKTI), containing two Kazal-type and 13 nonKazal-type domains, is an efficient inhibitor of multiple serine proteinases, among them plasmin, subtilisin A, cathepsin G, elastase, and trypsin. To gain insight into the structure and function of some of these domains, a portion of the cDNA coding for LEKTI domains 6-9' was cloned and expressed in Sf9 cells using the baculovirus expression vector system (BEVS). Through a single purification step using a Co2+ column, 3-4 mg of purified recombinant LEKTI-domains 6-9' (rLEKTI6-9') with the predicted molecular mass of 34.6 kDa was obtained from the cell pellet of a 1-L culture. Unlike full-length LEKTI, rLEKTI6-9' inhibited trypsin and subtilisin A but not plasmin, cathepsin G, or elastase. The inhibition of trypsin and subtilisin A by rLEKTI6-9' occurred through a noncompetitive mechanism, with inhibitory constants (Ki) of 356 +/- 12 and 193 +/- 10 nM, respectively. On the basis of the Ki values, rLEKTI6-9' was determined to be a more potent trypsin inhibitor and a less potent subtilisin A inhibitor than the full-length LEKTI. In contrast to LEKTI domains 6-9', recombinant LEKTI domain 6 does not inhibit subtilisin A but competitively inhibited trypsin with a Ki of 200 +/- 10 nM. Taking LEKTI6-9' as an example, the BEVS should facilitate the structure-function analysis of naturally occurring processed LEKTI forms that have physiological relevance.

Animals↗
PubMed2004

Production of serpins using baculovirus expression systems.

Headpin is a novel serine proteinase inhibitor (serpin) that is downregulated in many established HNSCC tumor cell lines and human oral SCC specimens. The use of the bacterial and yeast expression systems for headpin resulted in poor yields and proteins with low inhibitory activity. To circumvent these problems, we have developed a baculovirus-insect cell system for high-yield expression as well as fully functional protein. Here, we describe the strategies and methods used to express headpin in an insect cell heterologous system. In addition, procedures to purify the recombinant proteins are described. A metal affinity column followed by a gel-filtration chromatography provides a rapid and efficient method for large quantity preparation of headpin. This method should be useful as an alternative expression system for those serpins that are not purifiable when expressed using the Escherichia coli or yeast expression system.

Animals↗
PubMed2004

SPINK5 and Netherton syndrome: novel mutations, demonstration of missing LEKTI, and differential expression of transglutaminases.

Netherton syndrome (NTS) is an autosomal recessive congenital ichthyosis featuring chronic inflammation of the skin, hair anomalies, epidermal hyperplasia with an impaired epidermal barrier function, failure to thrive and atopic manifestations. The disease is caused by mutations in the SPINK5 gene encoding the serine proteinase inhibitor lympho-epithelial Kazal-type inhibitor (LEKTI). Sequence analyses of SPINK5 in seven NTS patients from five different families allowed us to identify two known and three novel mutations all creating premature termination codons. We developed a monoclonal antibody giving a strong signal for LEKTI in the stratum granulosum of normal skin and demonstrated absence of the protein in NTS epidermis. Immunoblot analysis revealed presence of full length LEKTI and of LEKTI cleavage fragments in normal hair roots, whereas in NTS hair roots LEKTI and its cleavage products were completely missing. Transglutaminase1 activity was present throughout almost the entire suprabasal epidermis in NTS, whereas in normal skin it is restricted to the stratum granulosum. In contrast, immunostaining for transglutaminase3 was absent or faint. Moreover, comparable with the altered pattern in psoriatic skin the epidermis in NTS strongly expressed the serine proteinase inhibitor SKALP/elafin and the anti-microbial protein human beta-defensin 2. These studies demonstrate LEKTI deficiency in the epidermis and in hair roots at the protein level and an aberrant expression of other proteins, especially transglutaminase1 and 3, which may account for the impaired epidermal barrier in NTS.

Adult↗
PubMed2003

Resetting the histone code at CDKN2A in HNSCC by inhibition of DNA methylation.

Head and neck squamous cell carcinoma (HNSCC) is the fifth most frequent cancer in the US. Several genetic and epigenetic alterations are associated with HNSCC tumorigenesis, including inactivation of CDKN2A, which encodes the p16 tumor suppressor, in cell lines and primary tumors by DNA methylation. Reactivation of tumor suppressor genes by DNA-demethylating agents and histone deacetylase (HDAC) inhibitors shows therapeutic promise for other cancers. Therefore, we investigated the ability of these agents to reactivate p16 in Tu159 HNSCC cells. Treatment of cells with 5-aza-2'deoxycytidine (5-aza-dC) increases CDKN2A expression and slightly increases histone H3 acetylation at this gene. No reactivation of CDKN2A is observed upon treatment with the HDAC inhibitor trichostatin A (TSA), but synergistic reactivation of CDKN2A is observed upon sequential treatment of Tu159 cells with both 5-aza-dC and TSA. Silencing of CDKN2A in Tu159 cells is correlated with increased methylation of histone H3 at lysine 9 and decreased methylation at lysine 4 relative to the upstream p15 gene promoter. Interestingly, global levels of H3-K9 methylation are decreased upon treatment with 5-aza-dC. Together these data indicate that DNA methylation is a dominant epigenetic mark for silencing of CDKN2A in Tu159 tumor cells. Moreover, changes in DNA methylation can reset the histone code by impacting multiple H3 modifications.

Animals↗
PubMed2003

Inhibition of serine proteinases plasmin, trypsin, subtilisin A, cathepsin G, and elastase by LEKTI: a kinetic analysis.

The human LEKTI gene encodes a putative 15-domain serine proteinase inhibitor and has been linked to the inherited disorder known as Netherton syndrome. In this study, human recombinant LEKTI (rLEKTI) was purified using a baculovirus/insect cell expression system, and the inhibitory profile of the full-length rLEKTI protein was examined. Expression of LEKTI in Sf9 cells showed the presence of disulfide bonds, suggesting the maintenance of the tertiary protein structure. rLEKTI inhibited the serine proteinases plasmin, subtilisin A, cathepsin G, human neutrophil elastase, and trypsin, but not chymotrypsin. Moreover, rLEKTI did not inhibit the cysteine proteinase papain or cathepsin K, L, or S. Further, rLEKTI inhibitory activity was inactivated by treatment with 20 mM DTT, suggesting that disulfide bonds are important to LEKTI function. The inhibition of plasmin, subtilisin A, cathepsin G, elastase, and trypsin by rLEKTI occurred through a noncompetitive-type mechanism, with inhibitory constants (K(i)) of 27 +/- 5, 49 +/- 3, 67 +/- 6, 317 +/-36, and 849 +/- 55 nM, respectively. Thus, LEKTI is likely to be a major physiological inhibitor of multiple serine proteinases.

Amino Acid Sequence↗
PubMed2003

Inhibition of the cysteine proteinases cathepsins K and L by the serpin headpin (SERPINB13): a kinetic analysis.

Headpin (SERPINB13) is a novel member of the serine proteinase inhibitor (Serpin) gene family that was originally cloned from a keratinocyte cDNA library. Western blot analysis using a headpin-specific antiserum recognized a protein with the predicted M(r) of 44kDa in lysates derived from a transformed keratinocyte cell line known to express headpin mRNA. Similarity of the reactive-site loop (RSL) domain of headpin, notably at the P1-P1(') residues, with other serpins that inhibit cysteine and serine proteinases suggests that headpin may inhibit similar proteinases. This study demonstrates that recombinant headpin indeed inhibits cathepsins K and L, but not chymotrypsin, elastase, trypsin, subtilisin A, urokinase-type plasminogen activator, plasmin, or thrombin. The second-order rate constants (k(a)) for the inhibitory reactions of rHeadpin with cathepsins K and L were 5.1+/-0.6x10(4) and 4.1+/-0.8x10(4)M(-1)s(-1), respectively. Headpin formed SDS-stable complexes with cathepsins K and L, a characteristic property of inhibitory serpins. Interactions of the RSL domain of headpin with cathepsins K and L were indicated by cleavage of headpin near the predicted P1-P1(') residues by these proteinases. These results demonstrate that the serpin headpin possesses specificity for inhibiting lysosomal cysteine proteinases.

Amino Acid Sequence↗