Immunohistochemical distribution of adult T-cell leukemia-derived factor/thioredoxin in epithelial components of normal and pathologic human skin conditions

Thioredoxin-interacting protein regulates keratinocyte differentiation: Implication of its role in psoriasis

Thioredoxin-interacting protein (TXNIP), also known as Vitamin-D upregulated protein-1 (VDUP-1), interacts with thioredoxin to regulate redox responses and participates in diverse disorders including metabolic, cardiovascular, inflammatory and malignant diseases. Psoriasis is characterized by chronic skin inflammation and an aberrant pattern of keratinocyte differentiation. Clinically, psoriasis is associated with various cardiometabolic comorbidities but studies on TXNIP's biological role in skin disorders are limited. In this study, we investigated TXNIP expression in psoriasis and its regulation in normal human epidermal keratinocytes (NHEKs), and then explored how TXNIP regulated skin keratinocyte differentiation to determine its role in psoriasis pathogenesis. Our immunohistochemical study demonstrated extensive TXNIP expression in the upper and lower epidermis of psoriasis compared to predominant TXNIP expression in the basal layer of normal skin. 1, 25-dihydroxyvitamin D₃  suppressed but TGF-α and EGF enhanced TXNIP expression in NHEKs. An inducer of keratinocyte differentiation, phorbol 12-myristate 13-acetate (PMA), also diminished TXNIP expression, which was reversed by PKC-δ knockdown. TXNIP knockdown reduced PMA-induced involucrin and transglutaminse-1 expression, and increased p63 expression in NHEKs but did not significantly affect cell proliferation. H₂ O₂ -induced ROS production and EGFR phosphorylation decreased in NHEKs with TXNIP knockdown. Furthermore, PMA-induced PKC-δ phosphorylation, TGF-α, and EGF-triggered EGFR phosphorylation were attenuated by TXNIP knockdown. Our results unraveled the regulation and function of TXNIP expression in skin keratinocytes and the cross-regulation between TXNIP and EGFR signaling. These findings imply a role of TXNIP in psoriasis and provide insight into the possible impact of TXNIP regulators on the skin or psoriasis.

Proteomic analysis of human papillomavirus-related oral squamous cell carcinoma: identification of thioredoxin and epidermal-fatty acid binding protein as upregulated protein markers in microdissected tumor tissue

Human papillomavirus (HPV) infection has been identified as an etiologic agent for a subset of oral squamous cell carcinoma (OSCC) with increasing incidence. HPV DNA-positivity may confer better prognosis but the related oncogenic mechanisms are unknown. For the identification of HPV relevant proteins, we analyzed microdissected cells from HPV DNA-positive (n = 17) and HPV DNA-negative (n = 7) OSCC tissue samples. We identified 18 proteins from tumor tissues by peptide fingerprint mapping and SELDI MS that were separated using 2-DE. Among a number of signals that were detected as significantly different in the protein profiling analysis, we identified thioredoxin (TRX) and epidermal-fatty acid binding protein as upregulated in HPV related tumor tissue. This study, investigating for the first time proteomic changes in microdissected HPV infected tumor tissue, provides an indication on the oncogenic potential of viruses.

Increased expression of thioredoxin-1, vascular endothelial growth factor, and redox factor-1 is associated with poor prognosis in patients with liver metastasis from colorectal cancer

We examined whether the expression of thioredoxin-1 (Trx-1) was associated with patient prognosis after liver resection for metastatic colorectal cancer. Eighty-four patients underwent resection of liver metastases from colorectal cancer, leaving no macroscopic evidence of residual tumor. Immunohistochemical study was performed to evaluate the relation among Trx-1, vascular endothelial growth factor (VEGF), and redox factor-1 (Ref-1) expression and the clinicopathologic characteristics and patient survival. Thirty-seven patients (44.0%) with Trx-1-positive metastases had shorter survival after primary liver resection (P = .0003) than the 47 patients (56.0%) with Trx-1-negative metastases. The percentage VEGF-positive and Ref-1-positive metastases was significantly higher in patients with Trx-1 expression (P = .0009 and .0002, respectively). Multivariate analysis revealed that Trx-1 expression was an independent prognostic factor. Expression of VEGF and Ref-1 is associated with Trx-1 overexpression, which is related to a poor prognosis in patients with liver metastases from colorectal cancer.

The Expression of Vitamin D-Upregulated Protein 1 in Skin and its Interaction with Sciellin in Cultured Keratinocytes

Sciellin, a precursor of the cornified envelope, contains a LIM domain that is known to function as a protein interaction module. In this study we used the yeast two-hybrid system to find proteins interacting with sciellin and identified vitamin D-upregulated protein 1 (VDUP1). This protein had not been reported in skin, but was shown in a number of cells to interact with reduced thioredoxin and regulate its function. Using an affinity VDUP1 column and an extract of cultured keratinocytes it was shown that VDUP1 and sciellin interacted. By immunohistochemistry VDUP1 was localized to the basal layer of normal human epidermis and the inner and outer root sheaths but not the matrix of the hair follicle. In the proliferative epidermis of psoriasis, VDUP1 was most highly expressed in the upper epidermal layers. In cultured keratinocytes, VDUP1 and sciellin were more highly expressed in cells undergoing differentiation. Colocalization of the proteins could be demonstrated by immunohistochemistry in parts of the follicle, psoriatic epidermis, and cultured keratinocytes. Our results suggested that VDUP1 could have a unique role in epidermis regulating the conversion of postmitotic cells to differentiating ones.

Increased expression of thioredoxin-1 in human colorectal cancer is associated with decreased patient survival

Thioredoxin-1 is a redox protein that, when overexpressed, causes increased cancer-cell growth and inhibited apoptosis. Thioredoxin-1 expression has been reported to be increased in several human primary tumors, but its relationship to tumor progression and patient survival has not been established. We studied the expression of thioredoxin-1 as measured with immunohistochemical staining in paraffin-embedded human normal colonic mucosa, adenomatous polyps, and primary and metastatic colorectal cancer. Thioredoxin-1 expression was not increased in 12 colorectal adenomatous polyps, compared with 8 samples of normal colonic mucosa, but was significantly increased in 12 primary colorectal cancers (P <.01). Thioredoxin-1 expression was not significantly different in primary lymph-node metastases and the primary colorectal cancer. Using colorectal cancer samples from 37 subjects for whom survival data was available, we found that thioredoxin-1 expression increased with Dukes stage, although the association was not statistically significant (P =.077). We noted a significant association between thioredoxin-1 expression and patient survival (P =.004); higher score was associated with decreased survival. When adjusted for Dukes stage, thioredoxin-1 expression showed a statistically significant association with survival (P =.012). The work shows that increased thioredoxin-1 expression is a relatively late event in colorectal carcinogenesis and provides evidence in a small group of subjects with colorectal cancer of Dukes stages A through D that thioredoxin-1 expression may be an independent marker of patient prognosis.

Augmented expression of peroxiredoxin I in lung cancer

Comparative proteome analysis was performed between human normal (BEAS 2B) and malignant (A549) lung epithelial cells in an attempt to identify novel biomarkers of lung cancer. Approximately 500 protein spots could be separated by mini two-dimensional electrophoresis and visualized with Coomassie blue R-250. Among those relatively abundant proteins, eight spots were changed more than twofold reproducibly and identified by peptide mass fingerprints using mass spectrometry and database search. The increased proteins in A549 were aldehyde dehydrogenase, peroxiredoxin I, fatty acid binding protein, aldoketoreductase, and destrin, whereas the decreased proteins were galectin-1, transgelin, and stathmin. Since human lung is exposed to continuous oxidative stress, antioxidant enzyme peroxiredoxin I was selected for further investigation and its augmented expression was confirmed in cancer tissues compared to normal tissues from lung cancer patients, suggesting peroxiredoxin I as a potential biomarker of lung cancer.

Properties and biological activities of thioredoxins

The mammalian thioredoxins are a family of small (approximately 12 kDa) redox proteins that undergo NADPH-dependent reduction by thioredoxin reductase and in turn reduce oxidized cysteine groups on proteins. The two main thioredoxins are thioredoxin- 1, a cytosolic and nuclear form, and thioredoxin-2, a mitochondrial form. Thioredoxin-1 has been studied more. It performs many biological actions including the supply of reducing equivalents to thioredoxin peroxidases and ribonucleotide reductase, the regulation of transcription factor activity, and the regulation of enzyme activity by heterodimer formation. Thioredoxin-1 stimulates cell growth and is an inhibitor of apoptosis. Thioredoxins may play a role in a variety of human diseases including cancer. An increased level of thioredoxin-1 is found in many human tumors, where it is associated with aggressive tumor growth. Drugs are being developed that inhibit thioredoxin and that have antitumor activity.

Properties and biological activities of thioredoxins

The mammalian thioredoxins are a family of small (approximately 12 kDa) redox proteins that undergo NADPH-dependent reduction by thioredoxin reductase and in turn reduce oxidized cysteine groups on proteins. The two main thioredoxins are thioredoxin-1, a cytosolic and nuclear form, and thioredoxin-2, a mitochondrial form. Thioredoxin-1 has been studied more. It performs many biological actions including the supply of reducing equivalents to thioredoxin peroxidases and ribonucleotide reductase, the regulation of transcription factor activity, and the regulation of enzyme activity by heterodimer formation. Thioredoxin-1 stimulates cell growth and is an inhibitor of apoptosis. Thioredoxins may play a role in a variety of human diseases including cancer. An increased level of thioredoxin-1 is found in many human tumors, where it is associated with aggressive tumor growth. Drugs are being developed that inhibit thioredoxin and that have antitumor activity.

The role of the redox protein thioredoxin in cell growth and cancer

The thioredoxins are ubiquitous proteins containing a conserved -Trp-Cys-Gly-Pro-Cys-Lys- redox catalytic site. Mammalian thioredoxin family members include thioredoxin-1 (Trx1), mitochondrial thioredoxin-2 (Trx2), and a larger thioredoxin-like protein, p32TrxL. Thioredoxin is reduced by NADPH and thioredoxin reductase and, in turn reduces oxidized cysteine groups on proteins. When thioredoxin levels are elevated there is increased cell growth and resistance to the normal mechanism of programmed cell death. An increase in thioredoxin levels seen in many human primary cancers compared to normal tissue appears to contribute to increased cancer cell growth and resistance to chemotherapy. Mechanisms by which thioredoxin increases cell growth include an increased supply of reducing equivalents for DNA synthesis, activation of transcription factors that regulate cell growth, and an increase in the sensitivity of cells to other cytokines and growth factors. The mechanisms for the inhibition of apoptosis by thioredoxin are just now being elucidated. Because of its role in stimulating cancer cell growth and as an inhibitor of apoptosis, thioredoxin offers a target for the development of drugs to treat and prevent cancer.

Peroxiredoxin I expression in oral cancer: a potential new tumor marker

This study investigates the applicability of the novel antioxidant protein, peroxiredoxin (Prx) I as a marker for tumor status in oral squamous cell carcinoma (SCC). Samples from 53 patients with SCC in the oral cavity were examined by immunohistochemistry. Correlations between the expression level of Prx I and proliferating cell nuclear antigen (PCNA), the clinical features of tumors, and their histopathological classifications were statistically analyzed. Cases exhibiting low Prx I expression level included significantly more with larger tumor mass cases (T-category, P=0.004), positive lymph node metastasis (N-category, P=0.015), advanced stage (P=0.002), and poorly differentiated cells (P=0.020). There was no significant difference between Prx I expression and the other indices.

A redox-inactive thioredoxin reduces growth and enhances apoptosis in WEHI7.2 cells

Cancer cell lines transfected with thioredoxin show increased anchorage-independent growth and decreased sensitivity to induction of apoptosis by a number of anticancer drugs. The present studies were undertaken to evaluate further the role of thioredoxin in cell growth and drug-induced apoptosis. A redox-inactive mutant thioredoxin was stably transfected into WEHI7.2 mouse lymphocytic leukemia cells and two clones were examined for growth characteristics and the induction of apoptosis by dexamethasone, etoposide, doxorubicin, and staurosporine. These clones each exhibited a 71% increase in doubling time in solution and a 20 and 75% reduction in colony formation in soft agarose. The transfected cells also showed increased susceptibility to apoptosis induced by dexamethasone, etoposide, doxorubicin, and staurosporine compared with controls. The results of this study suggest that thioredoxin can regulate the growth rate of cells and that thioredoxin is a critical component in the pathway leading to drug-induced apoptosis in WEHI7.2 cells.

Redox control of caspase-3 activity by thioredoxin and other reduced proteins

Caspases are cysteine proteinases that play a critical role in the execution phase of apoptosis. The active site cysteine residue must be reduced for caspase activity. Thioredoxins are redox proteins that catalyze the reduction of cysteine residues. We have examined the ability of various recombinant human thioredoxins to activate caspase-3. The EC(50) for caspase-3 activation by reduced thioredoxin-1 was 2.5 microM, by reduced glutathione 1.0 mM and by dithiothreitol 3.5 mM. A catalytic site redox-inactive mutant thioredoxin-1 was almost as active as thioredoxin-1 in activating caspase-3. Caspase activation was shown to correlate with the number of reduced cysteine residues in the thioredoxins. Reduced insulin and serum albumin were as effective on a molar basis as thioredoxin-1 in activating caspase-3. Thus, caspase-3 activation is not a specific effect of thioredoxins but is a property shared by other reduced proteins.

Detection of thioredoxin in gastric cancer: association with histological type

Thioredoxin (TRX) is a redox-active protein with multiple intra- and extracellular functions. This protein exists ubiquitously in all life forms, from primitive living cells, such as Escherichia coli and yeast, to higher mammals. Recently, augmentation of the expression and transcription level of TRX has been reported in tumors of various organs. In this study, we examined the expression of TRX in gastric cancer with respect to its histological type and depth of invasion. The association with cell proliferation was also studied. Results of histochemical analysis of surgical specimens as well as cytochemical analysis and Northern blot analysis of gastric cancer cell lines indicated that TRX is predominantly expressed in undifferentiated type gastric cancer rather than in the differentiated type. Neither the depth of tumor invasion nor cell proliferation significantly determined the staining intensity for TRX.

Membranous and soluble forms of Fas antigen in cutaneous lupus erythematosus

The role of Fas-mediated apoptosis in cutaneous lupus erythematosus (LE) is still unclear, although the Fas/FasL system has been investigated in autoimmune diseases in relation to impaired apoptosis. In order to elucidate the connections between acute cutaneous LE (ACLE) and chronic cutaneous LE (CCLE), we determined the expression of membranous Fas antigen (mFas) on peripheral blood mononuclear cells (PBMC) by flow cytometry and the levels of the soluble form of the Fas antigen (sFas) in sera. The ratio and the mean fluorescence intensity of mFas were much higher in ACLE patients than in others, including patients with CCLE and atopic dermatitis and normal healthy controls. The levels of sFas in ACLE and CCLE patients were also elevated, and there was a significant increase in sFas levels in ACLE patients over that in CCLE patients. Immunohistochemical studies revealed that Fas antigen was predominantly expressed on infiltrating cells around blood vessels and appendages in ACLE and CCLE patients. Based on these findings, it is suggested that the expression of Fas antigen is closely associated with the activation of circulating lymphocytes, especially in ACLE patients, but is not directly associated with keratinocyte damage.

Induction of human thioredoxin in cultured human retinal pigment epithelial cells through cyclic AMP-dependent pathway; involvement in the cytoprotective activity of prostaglandin E1

Human thioredoxin is one of the oxidative stress-inducible proteins and has a protective function against oxidant-induced injury. To evaluate the possible involvement of thioredoxin in the cytoprotective function of prostaglandin E1, we analysed the effect of prostaglandin E1 on cellular injury by hydrogen peroxide and intracellular thioredoxin induction. Cellular survival of human retinal pigment epithelial cell line, established from normal retinal pigment epithelial cells, following exposure to hydrogen peroxide was markedly improved by pretreatment of 1 microm prostaglandin E1. Thioredoxin expression was augmented in a dose-dependent manner when retinal pigment epithelial cells were pretreated with 10 nm-1 microm prostaglandin E1 1 hr before the exposure to hydrogen peroxide. Intracellular cyclic AMP level was elevated by Prostaglandin E1 when the cells were simultaneously exposed to hydrogen peroxide. Forskolin, an activator of adenylate cyclase, and dibutylyl cAMP, a cyclic AMP analog, could also induce thioredoxin and extend survival of retinal pigment epithelial cells. On the other hand, thioredoxin induction and cellular protection by prostaglandin E1 was blocked by Rp diastereoisomer of cyclic adenosine 3', 5', monophosphorothioate, a competitive inhibitor of cyclic AMP dependent protein kinase. Thioredoxin induction was augmented significantly by pretreatment with prostaglandin I2, a stimulator of cyclic AMP dependent signal pathway, while treatment with prostaglandin F2alpha, a stimulator of inositol phosphate-dependent signal pathway, failed to enhance thioredoxin. These findings indicate that prostaglandin E1 has a cytoprotective activity against oxidative injury, partly through thioredoxin induction via cyclic AMP dependent pathway.

Analysis of localization of adult T-cell leukemia-derived factor in the transient ischemic rat retina after treatment with OP-1206 alpha-CD, a prostaglandin E1 analogue

Prostaglandin E1 (PGE1) is commonly used in therapy for obstructive diseases, including ischemic retinopathy, in which pathogenetic reactive oxygen intermediates are responsible. However, the mechanism(s) of PGE1 in reducing tissue damage is still unclear. Adult T-cell leukemia-derived factor/human thioredoxin (ADF) is induced by oxidative stresses and has protective activity against oxidative cellular injury. To evaluate the possible involvement of ADF in the tissue-protective effect of PGE1, we analyzed ADF expression immunohistochemically using a rat transient retinal ischemia model. Rats were treated orally with 300 micrograms/kg/day OP-1206 alpha-cyclodextrin clathrate (OP-1206), a stable PGE1 analogue, for 14 days after photodynamic retinal vascular thrombosis by rose Bengal. Rats without any OP-1206 treatment were used as controls. In the OP-1206-treated rats, minimal retinal atrophy due to ischemia/reperfusion was observed histologically up to 14 days, whereas in the non-treated rats the inner layer of the retina became markedly atrophic. In parallel with the histological change, after 14 days following thrombosis ADF immunoreactivity was preserved on retinal pigment epithelial cells in the OP-1206-treated rats, whereas it was diminished in the non-treated rats. These findings suggest an important role for ADF in the OP-1206-dependent suppression of retinal tissue damage caused by oxidative insult.

Immunocytochemical localization of thioredoxin in human trophoblast and decidua

An immunocytochemical investigation into the expression of thioredoxin in human reproductive tissues was performed using monoclonal antibodies produced against recombinant human thioredoxin. First trimester and term human placental villi, decidua and term fetal membranes were examined for thioredoxin content and cellular localization. In first trimester tissue strong thioredoxin staining was observed in the underlying cytotrophoblast cells and in the stromal cells present in the decidua, but not in the syncytiotrophoblast surrounding the chorionic villi. In term placental villi very little thioredoxin was observed. Term fetal membranes proved to be a rich source of thioredoxin, the most intense staining was seen in the cytotrophoblast cells in the chorionic membrane, with the amnion and decidua also showing positive immunoreactivity. The potential role/s that thioredoxin may play within the placental bed is considered.

Induction of ADF/TRX by oxidative stress in keratinocytes and lymphoid cells

Adult T-cell leukemia-derived factor (ADF)/human thioredoxin (TRX) has thiol-dependent reducing activities and is known to have regulatory roles on the DNA-protein interaction and cell activation. Inducive effect of ultraviolet (UV) has been indicated because of the enhanced expression of ADF/TRX in epidermal cells of sun-exposed skin, as determined by immunohistochemical staining with antibody against recombinant ADF (rADF). We studied the effect of UVB irradiation and other oxidative stress on the expression of ADF/TRX in epithelial cells as well as lymphoid cells, as HTLV-1 and Epstein-Barr virus-transformed lymphoid cells constitutively produce ADF/TRX. Using immunohistochemical staining anti-ADF antibody, the enhancement of ADF/TRX expression on primary culture of human keratinocytes was demonstrated, 12 h after 20 mJ/cm2 UVB irradiation. Western blot analysis of the ADF/TRX protein in the cell lysates also showed the significant induction. In in situ hybridization, induction of ADF/TRX mRNA was detected after 4 h of UV exposure. ADF/TRX was also induced in a HTLV-1 (+) T-cell line, MT-1, by UVB or H2O2 dose dependently. The augmentation of ADF/TRX was observed 6 h after treatment of H2O2.