Utility of pVHL, maspin, IMP3, S100P and Ki67 in the distinction of autoimmune pancreatitis from pancreatic ductal adenocarcinoma.

Morphology plays an important role in the distinction of autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC). However, we aimed to determine the utility of immunohistochemical tumor markers to contribute in the distinction of these entities. In surgical specimens with AIP (n = 20), PDAC (n = 20) and normal pancreas (n = 20), the expression of pVHL, maspin, IMP3, S100P and Ki67 was examined. We evaluated intralobular reactive ducts / acinoductal metaplasia (ILDs) and extralobular ducts (ELDs) in AIP, neoplastic glands in PDAC, and ductal epithelium in the normal pancreas, using a five-tiered scoring system. The Ki67 hot spot index (Ki67-HSPI) was determined manually and using automated digital imaging analysis of virtual double stains of Ki67 and CK8. Besides, sequential dual-immunohistochemical staining of maspin/pVHL, maspin/IMP3 and Ki67/maspin was performed in a subset of the specimens. Strong overexpression of IMP3, maspin, S100P and Ki67 and loss of pVHL was observed in PDAC compared to AIP and normal pancreas. In AIP however, focal and weak aberrant expression was observed with the following proportions in ILDs/ELDs: pVHL in 45 %/85 %, maspin in 30 %/70 %, IMP3 in 55 %/5%, S100P in 10 %/35 % and Ki67-HSPI >20 % in 15 %/70 %. At least two markers were aberrantly expressed in ILDs/ELDs in 45 %/60 %. The aberrant expression was more pronounced in type 2 AIP compared to type 1. In conclusion, our data indicate that pVHL, maspin, IMP3, S100P and Ki67 can be focal and weak aberrantly expressed in AIP. However, when used as a panel, these markers seem to be useful for the differentiation of AIP from PC.

Expression of von Hippel-Lindau tumor suppressor protein (pVHL) characteristic of tongue cancer and proliferative lesions in tongue epithelium.

BACKGROUND: Patients with tongue cancer frequently show loss of heterozygosity (LOH) of the von Hippel-Lindau (VHL) tumor suppressor gene. However, expression of VHL protein (pVHL) in tongue cancer has rarely been investigated and remains largely unknown. We performed immunohistochemical staining of pVHL in tongue tissues and dysplasia, and examined the association with LOH and its clinical significance. METHODS: Immunohistochemical staining of pVHL in formalin-fixed, paraffin-embedded sections of cancerous and other tissues from 19 tongue cancer patients showed positivity for LOH of VHL in four samples, negativity in four samples, and was non-informative in 11 samples. The staining pattern of pVHL was also compared with those of cytokeratin (CK) 13 and CK17. RESULTS: In normal tongue tissues, pVHL staining was localized to the cytoplasm of cells in the basal layer and the area of the spinous layer adjacent to the basal layer of stratified squamous epithelium. Positive staining for pVHL was observed in the cytoplasm of cancer cells from all 19 tongue cancer patients. No differences as a result of the presence or absence of LOH were found. Notably, cytoplasm of poorly differentiated invasive cancer cells was less intensely stained than that of well and moderately differentiated invasive cancer cells. pVHL staining was also evident in epithelial dysplasia lesions with pVHL-positive cells expanding from the basal layer to the middle of the spinous layer. However, no CK13 staining was noted in regions of the epithelium, which were positive for pVHL. In contrast, regions with positive staining for CK17 closely coincided with those positive for pVHL. CONCLUSIONS: Positive staining for pVHL was observed in cancerous areas but not in normal tissues. pVHL expression was also detected in lesions of epithelial dysplasia. These findings suggest that pVHL may be a useful marker for proliferative lesions.

Immunoexpression patterns for Hypoxia-inducible Factor-1α and von Hippel-Lindau protein, in relation to Hsp90, of human brain tumors.

The pathogenesis of many tumors, including brain tumors, has been associated with hypoxia, which induces the transcriptional activity of hypoxia-inducible Factor-1α (HIF-1α). HIF-1α is normally degradated by the von Hippel-Lindau protein (pVHL) but, in hypoxia, pVHL/HIF-1α interaction is inhibited resulting in the nuclear accumulation of HIF-1α. Hsp90 (Heat shock protein 90), as a chaperone protein, plays a critical role for both stabilization of HIF-1α and degradation of pVHL. The aim of this study was to estimate immunohistochemically the expression levels of HIF-1α and pVHL, in relation to Hsp90, in different types of human brain tumors (42 gliomas, 9 medulloblastomas, and 38 meningiomas) using specific antibodies. The tumors were further divided into two groups according to the age of patients (≥19 years old or ⟨19 years old). Nuclear, for HIF-1α, and cytoplasmic, for pVHL and Hsp90, localization was detected in a high percentage of tumor cells in the majority of tumors. In astrocytomas, a significant, grade-dependent relationship for HIF-1α immunoexpression was observed (p⟨0.05). Furthermore, there was a significant correlation between pVHL and Hsp90 immunoexpression (p⟨0.01). The group of ≥19 years old patients with glioblastomas (WHO grade IV) demonstrated significantly increased immunoexpression for HIF-1α compared to pVHL (p⟨0.0001) and Hsp90 expression (p⟨0.01). In medulloblastomas, a significant correlation of HIF-1α with Hsp90 immunoexpression (p⟨0.05) was found. In meningiomas, no significant correlation for the expression of the three proteins was detected (p≥0.05). These results indicate that HIF-1α/pVHL/Hsp90 interactions may be implicated in biology of different types of brain tumors through different signaling mechanisms.

The von Hippel-Lindau tumour suppressor gene: uncovering the expression of the pVHL172 isoform.

BACKGROUND: The von Hippel-Lindau (VHL) gene encodes two mRNA variants. Variant 1 encodes two protein isoforms, pVHL213 and pVHL160, that have been extensively documented in the literature. Variant 2 is produced by alternative splicing of exon 2 and encodes a pVHL isoform of 172 amino acids with a theoretical molecular weight of 19 kDa (pVHL172), the expression of which has never been demonstrated so far due to the absence of suitable antibodies. METHODS: We have generated an anti-pVHL monoclonal antibody (JD-1956) using pVHL172 recombinant protein. We tested the antibody against exogenous or endogenous expressed proteins in different cell lines. We identified the pVHL172 using a silencing RNA strategy. The epitope of the antibody was mapped using a peptide array. RESULTS: We efficiently detected the three different isoforms of pVHL in cell lines and tumorigenic tissues by western blotting and immunohistochemistry and confirmed for the first time the endogenous expression of pVHL172. CONCLUSIONS: The endogenous expression of the three isoforms and particularly the pVHL172 has never been shown before due to a lack of a highly specific antibody since none of the available commercial antibodies distinguish the three isoforms of pVHL in cells or in both normal and cancerous human tissues. Evidence of pVHL172 expression emphasises the need to further study its implication in renal tumorigenesis and VHL disease.

Mutational status of VHL gene and its clinical importance in renal clear cell carcinoma.

The most common subtype of renal cell carcinoma is the clear cell type (ccRCC), accounting for 75 % of cases. Inactivation of VHL gene is thought to be an early event in ccRCC carcinogenesis. Our intention was to assess whether VHL mutational status might provide useful predictive or prognostic information in patients with ccRCC. VHL messenger RNA (mRNA) expression was analyzed by in situ hybridization and its protein by immunohistochemistry on a tissue microarray containing samples from 148 cases. This was validated by qRT-PCR on 62 cases, for which RNA was available. The mutation status was assessed in 91 cases by Sanger sequencing. VHL was found mutated in 57 % of cases, with missense mutations in 26 %, nonsense in 5 %, splice site in 13 %, deletions in 39 %, indels in 8 %, duplications in 8 %, and insertions in 2 % of the cases. The prevalence of mutations by exon was the following: exon 1, 47 %; exon 2, 27 %; and exon 3, 13 %. VHL protein was expressed in a high number of cases (80 %), but significant correlations were not found between protein expression, clinical data, and survival. Importantly, of the 91 samples evaluated by sequencing, 45 were mutated, and 87 % of those were strongly positive. We found 32 novel mutations in the VHL gene in ccRCC. The presence of mutations was not concordant with mRNA or protein expression. Nonsense mutations of the VHL gene appear to be related with poorer prognosis and survival.

Immunohistochemical distinction between intrahepatic cholangiocarcinoma and pancreatic ductal adenocarcinoma.

Distinction between primary intrahepatic cholangiocarcinoma (ICC) and metastatic pancreatic ductal adenocarcinoma (PDA) on a liver biopsy is essentially impossible histologically but has important clinical implications. In this study, 41 ICCs and 60 PDAs were immunohistochemically evaluated for the expression of S100P, pVHL, IMP3, maspin, MUC5AC, and CK17 proteins. The results showed pVHL expression in 29 (71%) ICCs but in only 3 (5%) PDAs. S100P, MUC5AC, and CK17 were frequently expressed in PDAs, seen in 57 (95%), 40 (67%), and 36 (60%) cases, respectively. In contrast, only 11 (27%), 5 (12%), and 5 (12%) ICC cases expressed these proteins. IMP3 was expressed in 37 (90%) ICC and 54 (90%) PDA cases with equal frequency. All 60 (100%) PDA and 30 (73%) ICC cases showed positive maspin immunoreactivity. A S100P-/pVHL+/MUC5AC-/CK17- staining pattern was essentially indicative of ICC, whereas the S100P+/pVHL-/MUC5AC+/CK17+ and S100P+/pVHL-/MUC5AC-/CK17+ staining patterns were suggestive of PDA. These observations demonstrate that S100P, pVHL, MUC5AC, and CK17 are a useful immunohistochemical panel that may help distinguish primary ICC from metastatic PDA.

Clinicopathological investigation of vascular endothelial growth factor and von Hippel-Lindau gene-related protein expression in immunohistochemically negative pituitary adenoma--possible involvement in tumor aggressiveness.

OBJECTIVES: Immunohistochemically negative pituitary adenoma is known to be relatively indolent, but a few aggressive and highly vascular cases have been reported, which sometimes show high expression of vascular endothelial growth factor (VEGF). METHODS: The present study investigated the relationship between high expression of VEGF and the clinical character of pituitary adenomas in 30 cases of immunohistochemically negative pituitary adenomas using immunohistochemical staining with monoclonal VEGF antibody and related upstream factors, including von Hippel-Lindau gene-related protein (pVHL). Correlations between the histological findings and the clinical characteristics were investigated. RESULTS: Immunohistochemical staining using VEGF antibody showed high expression in 7 (23.3%) and low expression in 23 (76.7%) cases, and pVHL staining showed high expression in 24 (80%) and low expression in 6 (20%) cases. The pVHL low expression group showed significantly higher expression of VEGF (p = 0.005019), and significantly higher recurrence or regrowth rate (p = 0.04535) than the pVHL high expression group, whereas Ki-67 labeling index of >3% also showed significant correlation with recurrence or regrowth rate (p = 0.01745). However, there was no significant correlation between pVHL staining and Ki-67 labeling index (p = 0.49978). CONCLUSION: Low expression of pVHL with high expression of VEGF may be involved in the unusual aggressive clinical course in some pituitary adenomas.

The expression pattern of Von Hippel-Lindau tumor suppressor protein, MET proto-oncogene, and TFE3 transcription factor oncoprotein in renal cell carcinoma in Upper Egypt.

BACKGROUND: Genetic alterations in renal cell carcinoma (RCC) involve tumor suppressor genes such as Von Hippel-Lindau (VHL); proto-oncogenes such as MET and transcription factors such as TFE3 oncoprotein. AIM: To examine the clinicopathologic features and the expression of some oncogenic molecules in various RCCs in patients from Upper Egypt. MATERIALS AND METHODS: The authors examined the expression pattern of pVHL; MET; and TFE3 proteins in 59 RCC using immunoperoxidase staining methods. The study group consisted of clear cell RCCs (CRCC); papillary RCCs type 1 (PRCC1); papillary RCCs type 2 (PRCC2); Xp11-2 translocation RCCs (XP11.2RCC); chromophobe RCCs (ChRCC); and sarcomatoid RCCs (SRCC). RESULTS: Variations were found in the expression of these molecules in the different types of RCCs. The mean age of RCCs among Egyptians was 52.70 ± 1.73 years; with male sex predominance. Mass lesion; pain; and hematuria were the main presenting features. Metastatic disease was more frequent with CRCC variant. pVHL expression was strong in PCRCC2; Xp11.2RCC; and ChRCC; moderate in CRCC; and weak in both PRCC1 and sarcomatoid RCC. MET protein expression was moderate in Xp11.2RCC; PRCC1; PRCC2; and sarcomatoid RCC. TFE3 protein expression was strong in Xp11.2RCC and PRCC2 variants. The expression was moderate in PRCC1; CRCC; ChRCC; and sarcomatoid RCC. Positive correlation was found in the expression of the different proteins (pVHL; MET; and TFE3) and some histological features (tumor grade; inflammation; necrosis and metastasis) and the presence of metastasis and some histological features (inflammation and/or necrosis). CONCLUSIONS: This study provides the first indication about the clinicopathologic features of RCCs in Upper Egypt. The variable expression of these molecules in the different variants of RCC suggests that several oncogenic pathways are operational in their development.

VHL mutations and dysregulation of pVHL- and PTEN-controlled pathways in multilocular cystic renal cell carcinoma.

Multilocular cystic renal cell carcinoma is a rare renal cell carcinoma with an excellent prognosis. To clarify the relationship with typical clear cell renal cell carcinoma, we evaluated 15 cases of multilocular cystic renal cell carcinomas diagnosed according to the 2004 WHO classification. Von Hippel Lindau (VHL) gene mutations were determined by whole genome amplification and direct sequencing. Carbonic anhydrase 9 (CAIX), a hypoxia-inducible factor (HIF) target, paired box gene 2 (PAX2), cyclin-dependent kinase inhibitor p27 and glycogen synthase kinase 3-ß (GSK3ß) were immunohistochemically evaluated as members of the VHL protein (pVHL)- and phosphatase and tensin homolog (PTEN)-controlled pathways. VHL mutations were identified in 3 of 12 (25%) tumors. Inactivated GSK3ß, decreased PTEN expression and PAX2 positivity were observed in the vast majority of the multilocular cystic renal cell carcinomas. Strong nuclear staining of p27 was seen in 14 of 15 cases. Compared with multilocular cystic renal cell carcinomas, expression frequencies of PAX2, p-GSK3ß, PTEN and CAIX were similar in a set of low-grade, early-stage clear cell renal cell carcinomas, whereas only 30% had strong p27 positivity. These results are consistent with the hypothesis that multilocular cystic renal cell carcinomas are related at the molecular level with clear cell renal cell carcinomas. Maintenance of a strong subcellular p27 expression in all multilocular cystic renal cell carcinomas analyzed may in part explain the excellent prognosis of these tumor patients.

S100P, von Hippel-Lindau gene product, and IMP3 serve as a useful immunohistochemical panel in the diagnosis of adenocarcinoma on endoscopic bile duct biopsy.

Histopathologic distinction between benign and malignant bile duct epithelial lesions on endoscopic biopsies can be extremely challenging because of limited material, crush artifact, and compounding inflammatory and/or reactive changes particularly after stent placement. In this study, a total of 72 endoscopic bile duct biopsies, including 40 adenocarcinomas and 32 benign cases, were immunohistochemically examined for the expression of S100P, von Hippel-Lindau gene product (pVHL), and IMP3 to evaluate their diagnostic value. The results showed that 36 adenocarcinomas (90%) exhibited strong nuclear and cytoplasmic staining for S100P, of which 30 (83.3%) showed diffuse immunoreactivity. Intermediate to strong cytoplasmic staining for IMP3 was demonstrated in 31 tumors (77.5%) (15 diffuse, 16 focal). Completely negative staining for pVHL was observed in 37 adenocarcinomas. In the remaining 3 tumors, focal (1) or diffuse (2) membranous and cytoplasmic pVHL immunoreactivity was detected. Twenty-eight tumors (70%) showed a S100P+/IMP3+/pVHL- staining pattern, 6 (15%) with a S100P+/IMP3-/pVHL- pattern, and 2 (5%) with a S100P-/IMP3+/pVHL- pattern. All 32 benign biopsies were completely negative for IMP3 with the exception of 2 cases with focal dysplasia where focal immunoreactivity was observed. Thirty benign biopsies (93.8%) were positive for pVHL with a diffuse staining pattern observed in 28 cases (93.3%). Eight benign biopsies (25%) showed focal S100P positivity. Twenty-two benign biopsies (68.8%) displayed a S100P-/IMP3-/pVHL+ staining pattern. In conclusion, an immunohistochemical panel consisting of S100P, pVHL, and IMP3 can be helpful in distinguishing adenocarcinoma from reactive epithelial changes on challenging bile duct biopsies. The findings of focal S100P and/or IMP3 expression with reciprocal loss of pVHL immunoreactivity in a few benign biopsies suggest a use of these markers in the detection of early epithelial dysplasia that may be beyond histologic recognition.

Phase II study of erlotinib in patients with locally advanced or metastatic papillary histology renal cell cancer: SWOG S0317.

PURPOSE: Patients with advanced papillary renal cell cancer (pRCC) have poor survival after systemic therapy; the reported median survival time is 7 to 17 months. In this trial, we evaluated the efficacy of erlotinib, an oral epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor in patients with advanced pRCC, a tumor type associated with wild-type von Hippel Lindau gene. PATIENTS AND METHODS: Patients with histologically confirmed, advanced, or metastatic pRCC were treated with erlotinib 150 mg orally once daily. A RECIST (Response Evaluation Criteria in Solid Tumors) response rate (RR) of > or = 20% was considered a promising outcome. Secondary end points included overall survival and 6-month probability of treatment failure. RESULTS: Of 52 patients registered, 45 were evaluable. The overall RR was 11% (five of 45 patients; 95% CI, 3% to 24%), and the disease control rate was 64% (ie five partial response and 24 stable disease). The median overall survival time was 27 months (95% CI, 13 to 36 months). Probability of freedom from treatment failure at 6 months was 29% (95% CI, 17% to 42%). There was one grade 5 adverse event (AE) of pneumonitis, one grade 4 thrombosis, and nine other grade 3 AEs. CONCLUSION: Although the RECIST RR of 11% did not exceed prespecified estimates for additional study, single-agent erlotinib yielded disease control and survival outcomes of interest with an expected toxicity profile. The design of future trials of the EGFR axis in pRCC should be based on preclinical or molecular data that define appropriate patient subgroups, new drug combinations, or potentially more active alternative schedules.

[Identification of VHL-associated changes in clear cell renal carcinoma: the application of combined genome and expression analyses]. / Identifizierung VHL-assoziierter Veränderungen im klarzelligen Nierenzellkarzinom: Anwendung von kombinierten Genom- und Expressionsanalysen.

Sporadic renal cell carcinoma (RCC) represents a heterogeneous tumor, which is traditionally classified into subtypes based on morphological criteria. In recent years high-throughput molecular analyses have been able to identify genomic and proteomic alterations in tumor cells. These markers are the basis for a molecular classification of RCC and bear prognostic value. However, an isolated consideration of genomic and proteomic alterations prevents deeper insights into the complex processes of carcinogenesis. Here we summarize recent studies focussing on this aspect of RCC and present a systems biology concept for the identification of novel tumor markers. These could be applied to improve future diagnosis and therapy of RCC.

An allelotype analysis indicating the presence of two distinct ovarian clear-cell carcinogenic pathways: endometriosis-associated pathway vs. clear-cell adenofibroma-associated pathway.

Patterns of allele loss (loss of heterozygosity (LOH)) were studied to identify the genetic backgrounds underlying the two putative carcinogenic pathways of ovarian clear-cell adenocarcinoma: carcinomas thought to arise in endometriosis (endometriosis-associated carcinomas, 20 cases) and carcinomas thought to be derived from clear-cell adenofibroma ((CCAF)-associated carcinomas, 14 cases). Each tumor was assessed for LOH at 24 polymorphic loci located on 12 chromosomal arms: 1p, 3p, 5q, 8p, 9p, 10q, 11q, 13q, 17p, 17q, 19p, and 22q. For all informative loci, the frequency of LOH was not statistically different between the two carcinoma groups: 38% (66/172 loci) in the endometriosis-associated carcinomas and 35% (40/113 loci) in the CCAF-associated carcinomas. In the endometriosis-associated carcinomas, LOH was detected at high frequencies (>50%) at 3p, 5q, and 11q and at low frequencies (<20%) at 8p, 13q, and 17p. In the CCAF-associated carcinomas, LOH was detected at high frequencies at 1p, 10q, and 13q and at low frequencies at 3p, 9p, 11q, and 17q. The frequencies of LOH at chromosomes 3p, 5q, and 11q were significantly higher in the endometriosis-associated carcinomas than in the CCAF-associated carcinomas (P = 0.026, 0.007, and 0.011, respectively). Immunohistochemical analysis demonstrated a close association between the allelic status of the 3p25-26 locus and levels of von Hippel-Lindau (VHL) protein expression (P = 0.0026). These data further support the presence of two distinct carcinogenic pathways to ovarian clear-cell adenocarcinoma; the allelic status of the 3p, 5q, and 11q loci may provide a means to identify the precursor lesions of these carcinomas.

Expression of hypoxia-inducible factor 1alpha, hypoxia-inducible factor 2alpha, and von Hippel-Lindau protein in epithelial ovarian neoplasms and allelic loss of von Hippel-Lindau gene: nuclear expression of hypoxia-inducible factor 1alpha is an independent prognostic factor in ovarian carcinoma.

The hypoxia-inducible factor (HIF) is a transcriptional factor with important roles in tumor biology. To clarify the possible involvement of the HIF-alpha subunit and von Hippel-Lindau (VHL) protein in the development and progression of ovarian carcinoma, we analyzed the immunohistochemical expressions of HIF-1alpha, HIF-2alpha, and VHL in 107 cases of epithelial ovarian tumors. In addition, we examined loss of heterozygosity (LOH) at VHL gene loci. The frequency of the cytoplasmic expression of HIF-2alpha in carcinomas was higher than that in benign and borderline tumors (P < .0001). Furthermore, the nuclear expression of HIF-1alpha and the cytoplasmic expression of HIF-2alpha were significantly higher in tumors of FIGO (International Federation of Gynecology and Obstetrics) stages III and IV than in those of stages I and II. On the other hand, the cytoplasmic expression of HIF-1alpha did not show differences among histological malignancies. There was a positive correlation between nuclear HIF-1alpha expression and vascular endothelial growth factor (rho = 0.320, P < .001). Although LOH at the VHL gene locus was frequent in ovarian carcinomas (24%), there is no significant correlation between LOH and loss of VHL expression. In 22 clear cell carcinomas, VHL expression showed a significantly negative correlation with the nuclear expression of HIF-1alpha (rho = -0.529, P = .0153). The log-rank test showed that nuclear positive immunostaining for HIF-1alpha (P = .002) and cytoplasmic positive immunostaining for HIF-2alpha (P = .0112) in tumor cells are associated with poor prognosis of patients with ovarian carcinoma. Multivariate analysis also showed that the nuclear expression of HIF-1alpha is an independent prognostic factor. These results show that the HIF-alpha subunit represents an important biomarker in the evaluation of the prognosis of patients with ovarian carcinoma.

Under-expression of VHL and over-expression of HDAC-1, HIF-1alpha, LL-37, and IAP-2 in affected skin biopsies of patients with psoriasis.

BACKGROUND: A feature of psoriasis is the rapid proliferation of keratinocytes, during which apoptosis is blocked and angiogenesis starts. It is known that tumor hypoxic cells produce histone deacetylase-1 (HDAC-1), which up-regulates hypoxia-inducible factor-1alpha (HIF-1alpha) and down-regulates von Hippel-Lindau (VHL) protein by up-regulating vascular endothelial growth factor (VEGF) expression. It has been reported recently that the porcine peptide PR39 (homologous to human LL-37) has angiogenic and antiapoptotic activity. Thus, LL-37, induced by insulin-like growth factor-1 (IGF-1), could help in the production of VEGF. PR39 also induces the expression of inhibitor of apoptosis protein-2 (IAP-2), which blocks apoptosis. The purpose of this work was to analyze whether these genes and their proteins are expressed in psoriatic biopsies. METHODS: Using semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) messenger RNA (mRNA) expression and immunohistochemical staining, we studied VHL, IAP-2, and related genes in skin biopsies from psoriatic patients and healthy subjects. RESULTS: An over-expression of the mRNA for HDAC-1, HIF-1alpha, LL-37, and IGF-1 in psoriatic skin, in comparison with skin from healthy subjects, was found. The antiangiogenic VHL mRNA and protein were under-expressed in psoriatic skin and highly expressed in healthy skin. The antiapoptotic IAP-2 was over-expressed in dermal endothelial cells from psoriatic skin. The pro-apoptotic Bax, Fas, and FasL mRNAs were expressed. CONCLUSIONS: These findings suggest that there could be an association of HDAC-1, HIF-1alpha, LL-37, VHL, and IAP-2 with angiogenic and apoptotic mechanisms in psoriasis.

Physiological activation of hypoxia inducible factor-1 in human skeletal muscle.

The human hypoxia inducible factor 1 (HIF-1) system is activated under various pathological conditions, yet less is known about its physiological regulation in healthy human tissue. We have studied the effect of exercise on the activation of HIF-1 in human skeletal muscle. Employing a model where oxygen consumption increases and oxygen tension can be manipulated, nine healthy male subjects performed 45 min of one-legged knee-extension exercise. Biopsies were taken before, directly after, and 30, 120, and 360 min after exercise. Exercise led to elevated HIF-1alpha protein levels and a more prevalent nuclear staining of HIF-1alpha. Interestingly, a concurrent decrease in von Hippel-Lindau tumor suppressor protein (VHL) levels was detected in some subjects. Moreover, exercise induced an increase in the DNA binding activity of HIF-1alpha. Characterization of gene expression by real-time PCR demonstrated that the HIF-1 target genes VEGF and EPO were activated. VEGF mRNA was further increased when blood flow to the exercising leg was restricted. In conclusion, these data clearly demonstrate that physical activity induces the HIF-1-mediated signaling pathway in human skeletal muscle, providing the first evidence that human HIF-1alpha can be activated during physiologically relevant conditions.