Tumor Suppressor Activity of Selenbp1, a Direct Nkx2-1 Target, in Lung Adenocarcinoma.

The Nkx2-1 transcription factor promotes differentiation of lung epithelial lineages and suppresses malignant progression of lung adenocarcinoma. However, targets of Nkx2-1 that limit tumor growth and progression remain incompletely understood. Here, direct Nkx2-1 targets are identified whose expression correlates with Nkx2-1 activity in human lung adenocarcinoma. Selenium-binding protein 1 (Selenbp1), an Nkx2-1 effector that limits phenotypes associated with lung cancer growth and metastasis, was investigated further. Loss- and gain-of-function approaches demonstrate that Nkx2-1 is required and sufficient for Selenbp1 expression in lung adenocarcinoma cells. Interestingly, Selenbp1 knockdown also reduced Nkx2-1 expression and Selenbp1 stabilized Nkx2-1 protein levels in a heterologous system, suggesting that these genes function in a positive feedback loop. Selenbp1 inhibits clonal growth and migration and suppresses growth of metastases in an in vivo transplant model. Genetic inactivation of Selenbp1, using CRISPR/Cas9, also enhanced primary tumor growth in autochthonous lung adenocarcinoma mouse models. Collectively, these data demonstrate that Selenbp1 is a direct target of Nkx2-1, which inhibits lung adenocarcinoma growth in vivo Implications: Selenbp1 is an important suppressor of lung tumor growth that functions in a positive feedback loop with Nkx2-1, and whose loss is associated with worse patient outcome. Mol Cancer Res; 16(11); 1737-49. ©2018 AACR.

SELENBP1 expression in the prefrontal cortex of subjects with schizophrenia.

Selenium binding protein 1 (SELENBP1) messenger RNA (mRNA) has previously been shown to be upregulated in the brain and blood from subjects with schizophrenia. We aimed to validate these findings in a new cohort using real-time PCR in Brodmann's Area (BA) 9, and to determine the disease specificity of increased SELENBP1 expression by measuring SELENBP1 mRNA in subjects with major depressive disorder and bipolar disorder. We then extended the study to include other cortical regions such as BA8 and BA44. SELENBP1 mRNA was higher in BA9 (P = 0.001), BA8 (P = 0.003) and BA44 (P = 0.0007) from subjects with schizophrenia. Conversely, in affective disorders, there was no significant difference in SELENBP1 mRNA in BA9 (P = 0.67), suggesting that the upregulation may be diagnosis specific. Measurement of SELENBP1 protein levels showed that changes in mRNA did not translate to changes in protein. In addition, chronic treatment of rats with antipsychotics did not significantly affect the expression of Selenbp1 in the cortex (P = 0.24). Our data show that elevated SELENBP1 transcript expression is widespread throughout the prefrontal cortex in schizophrenia, and confirm that this change is a consistent feature of schizophrenia and not a simple drug effect.

Selenium-binding protein 1 is associated with the degree of colorectal cancer differentiation and is regulated by histone modification.

The aim of the present study was to examine the regulation of selenium binding protein 1 (SELENBP1) expression in colorectal cancer (CRC). Samples of cancer tissue and adjacent normal mucosa were collected from 83 CRC patients, and analyzed for SELENBP1 expression by 2D-DIGE, immunoblotting, RT-PCR and immunostaining. Expression levels of SELENBP1, carcinoembryonic antigen (CEA) and alkaline phosphatase (AKP) were determined in cultures of human colon cancer cell lines (SW480, SW620 and HT29) folllowing treatment with i) sodium butyrate (NaB, 2 mM), a differentiation inducer; ii) Trichostatin A (TSA, 0.3 µM), a histone deacetylase inhibitor; or iii) 5'-aza-2'-deoxycytidine (5-Aza-dC, 5 µM), a DNA methylation inhibitor. SELENBP1 expression was found to be downregulated (2.54-fold) in the CRC samples as determined by 2D-DIGE and confirmed by immunoblotting and RT-PCR. SELENBP1 expression was correlated with the degree of differentiation, but not with TNM stage or lymph node metastasis, and was higher in benign polyps (1.97±0.57) than in CRC tissues (0.96±0.59). In the CRC cell lines, NaB treatment led to the upregulation of SELENBP1, CEA and AKP when compared with the untreated cells (2.24- to 4.82-fold). SELENBP1 was also upregulated in cells treated with TSA alone (1.25- to 3.64-fold), or in combination with 5-Aza-dC (1.32- to 4.13-fold). In CRC, the downregulated SELENBP1 expression was reactivated by inducing differentiation. Therefore, SELENBP1 is a potential pharmacological target for individualized CRC treatment.

A novel cell-cycle-indicator, mVenus-p27K-, identifies quiescent cells and visualizes G0-G1 transition.

The quiescent (G0) phase of the cell cycle is the reversible phase from which the cells exit from the cell cycle. Due to the difficulty of defining the G0 phase, quiescent cells have not been well characterized. In this study, a fusion protein consisting of mVenus and a defective mutant of CDK inhibitor, p27 (p27K(-)) was shown to be able to identify and isolate a population of quiescent cells and to effectively visualize the G0 to G1 transition. By comparing the expression profiles of the G0 and G1 cells defined by mVenus-p27K(-), we have identified molecular features of quiescent cells. Quiescence is also an important feature of many types of stem cells, and mVenus-p27K(-)-transgenic mice enabled the detection of the quiescent cells with muscle stem cell markers in muscle in vivo. The mVenus-p27K(-) probe could be useful in investigating stem cells as well as quiescent cells.

Proteomic profiling of the hypothalamus in a mouse model of cancer-induced anorexia-cachexia.

BACKGROUND: Anorexia-cachexia is a common and severe cancer-related complication but the underlying mechanisms are largely unknown. Here, using a mouse model for tumour-induced anorexia-cachexia, we screened for proteins that are differentially expressed in the hypothalamus, the brain's metabolic control centre. METHODS: The hypothalamus of tumour-bearing mice with implanted methylcholanthrene-induced sarcoma (MCG 101) displaying anorexia and their sham-implanted pair-fed or free-fed littermates was examined using two-dimensional electrophoresis (2-DE)-based comparative proteomics. Differentially expressed proteins were identified by liquid chromatography-tandem mass spectrometry. RESULTS: The 2-DE data showed an increased expression of dynamin 1, hexokinase, pyruvate carboxylase, oxoglutarate dehydrogenase, and N-ethylmaleimide-sensitive factor in tumour-bearing mice, whereas heat-shock 70 kDa cognate protein, selenium-binding protein 1, and guanine nucleotide-binding protein Gα0 were downregulated. The expression of several of the identified proteins was similarly altered also in the caloric-restricted pair-fed mice, suggesting an involvement of these proteins in brain metabolic adaptation to restricted nutrient availability. However, the expression of dynamin 1, which is required for receptor internalisation, and of hexokinase, and pyruvate carboxylase were specifically changed in tumour-bearing mice with anorexia. CONCLUSION: The identified differentially expressed proteins may be new candidate molecules involved in the pathophysiology of tumour-induced anorexia-cachexia.

Suppression of selenium-binding protein 1 in gastric cancer is associated with poor survival.

Gastric cancer is one of the leading causes of death in Asian countries, especially in China. Because of the lack of suitable biomarkers for early detection, most patients are diagnosed at late stages, and the 5-year survival rate is low. In this study, we used proteomic analysis to identify specific disease-associated proteins as potential clinical biomarkers in gastric cancer. Protein spots were determined and identified by 2-dimensional polyacrylamide gel electrophoresis and matrix-assisted laser desorption ionization time of flight mass spectrometry in 12 paired specimens. Twenty distinct proteins displaying a difference in expression of at least 1.8-fold between the tumor and compared adjacent normal mucosa were detected by 2-dimensional polyacrylamide gel electrophoresis, and one of the spots was selenium-binding protein 1 identified by matrix-assisted laser desorption ionization time of flight mass spectrometry. Selenium-binding protein 1 was significantly decreased or even absent in gastric cancer tissue compared with the adjacent normal mucosa in 44 paired specimens detected by reverse transcriptase-polymerase chain reaction and in 28 paired specimens detected by Western blot. Immunohistochemical staining result of 126 cases showed that the selenium-binding protein 1 level was correlated with differentiation, TNM stage, and lymph node metastasis (P < .05). The 3-year survival rate of patients with high expression of selenium-binding protein 1 was significantly higher than that of patients with low expression. Our results provided the first evidence of selenium-binding protein 1 as a potentially novel biomarker for prognosis of gastric cancer.

Reduced selenium-binding protein 1 is associated with poor survival rate in gastric carcinoma.

Human selenium-binding protein 1 (SBP1) is known to play a key role in the development and progression of many cancers. The role of SBP1 expression in gastric carcinoma (GC) is far from being fully established. The aim of the present study was to evaluate the expression of SBP1 in GC and correlate the findings with several clinicopathological features and prognosis. Tissue samples from 65 patients treated by gastric resection for GC with clinical stage II and III were used. Each sample was matched with the corresponding nonneoplastic epithelia tissues removed during the same surgery. Reverse transcriptase-polymerase chain reaction, immunostaining and Western blot analyses were used to detect the expression of SBP1 at the mRNA and protein levels, respectively. The associations between SBP1 expressions and clinicopathological features were analyzed. Expressions of SBP1 at both mRNA and protein levels were significantly lower in GC than those in the corresponding nonneoplastic epithelia tissues (P = 0.000). SBP1-negative expression had a significant relationship with high clinical stage (P = 0.038). Prognosis of SBP1-negative patients was significantly poorer than that of SBP1-positive patients (P = 0.001), and multivariate analysis further confirmed that SBP1 was an independent prognostic factor (P = 0.004). Thus, down-regulation of SBP1 may play a key role in the tumorigenic process of human GC. The correlation of SBP1 reduction in GC with clinical stage and survival proposes a prognostic role in GC.

Altered expression of selenium-binding protein 1 in gastric carcinoma and precursor lesions.

Selenium-binding protein 1 (SBP1) has been shown to be greatly reduced in various human cancers. The purpose of this study was to evaluate the expression of SBP1 in precursor lesions and gastric carcinoma (GC) and to discuss the specific role of SBP1 in gastric carcinogenesis. Using tissue microarray (TMA) technology and immunohistochemical (IHC) survey, SBP1 expressions were evaluated based on a semi-quantitative scoring system developed for this study in 25 paired of GC and corresponding nonneoplastic epithelia tissues, 21 gastric ulcer, 13 gastric polyp, 19 chronic atrophic gastritis, 20 intestinal metaplasia, and 16 dysplasia tissues. We found abundant expression of SBP1 in most precursor lesions in addition to the nonneoplastic epithelia tissues. However, the expression of SBP1 was severely suppressed in most of the GC tissues (P=0.000). Although no statistical differences were found between the expressions of SBP1 in gastric tissues with different levels of intestinal metaplasia or dysplasia (P>0.05), the reduction in SBP1 seems to be correlated with clinical stage of GC (P=0.044). Thus, SBP1 can be supposed as a diagnosis marker of GC. The suppression of SBP1 may be a late event in gastric carcinogenesis.

Hypoxia-inducible factor-1alpha suppresses squamous carcinogenic progression and epithelial-mesenchymal transition.

Hypoxia-inducible factor-1 (HIF-1) is a known cancer progression factor, promoting growth, spread, and metastasis. However, in selected contexts, HIF-1 is a tumor suppressor coordinating hypoxic cell cycle suppression and apoptosis. Prior studies focused on HIF-1 function in established malignancy; however, little is known about its role during the entire process of carcinogenesis from neoplasia induction to malignancy. Here, we tested HIF-1 gain of function during multistage murine skin chemical carcinogenesis in K14-HIF-1alpha(Pro402A564G) (K14-HIF-1alphaDPM) transgenic mice. Transgenic papillomas appeared earlier and were more numerous (6 +/- 3 transgenic versus 2 +/- 1.5 nontransgenic papillomas per mouse), yet they were more differentiated, their proliferation was lower, and their malignant conversion was profoundly inhibited (7% in transgenic versus 40% in nontransgenic mice). Moreover, transgenic cancers maintained squamous differentiation whereas epithelial-mesenchymal transformation was frequent in nontransgenic malignancies. Transgenic basal keratinocytes up-regulated the HIF-1 target N-myc downstream regulated gene-1, a known tumor suppressor gene in human malignancy, and its expression was maintained in transgenic papillomas and cancer. We also discovered a novel HIF-1 target gene, selenium binding protein-1 (Selenbp1), a gene of unknown function whose expression is lost in human cancer. Thus, HIF-1 can function as a tumor suppressor through transactivation of genes that are themselves targets for negative selection in human cancers.

Selenium-Binding Protein 1 expression in ovaries and ovarian tumors in the laying hen, a spontaneous model of human ovarian cancer.

OBJECTIVE: Reduced Selenium-Binding Protein 1 (SELENBP1) expression was recently shown in multiple cancers. There is little information on the expression and function of SELENBP1 in cancer progression. In order to develop a better understanding of the role of SELENBP1 in ovarian cancer, our objective was to determine if SELENBP1 is expressed in the normal ovaries and ovarian tumors in the egg-laying hen, a spontaneous model of human ovarian cancer. METHODS: SPB1 mRNA expression in normal ovary (n=20) and ovarian tumors (n=23) was evaluated by RT-PCR. Relative levels of mRNA were compared by quantitative RT-PCR (qRT-PCR) in selected samples. SELENBP1 protein expression was evaluated by 1D Western blot and immunohistochemistry with a commercial anti-human SELENBP1 antibody. RESULTS: SELENBP1 mRNA and protein was expressed in 100% of normal and ovarian tumors and qRT-PCR confirmed decreased mRNA expression in 80% of ovarian tumors. SELENBP1 was primarily localized in surface epithelial cells of normal ovaries. In ovaries containing early tumor lesions, SELENBP1 expression was reduced in the surface epithelium near the tumor and was expressed in tumor cells, while more distant regions with normal histology retained SELENBP1 expression in the surface epithelium. CONCLUSIONS: We have shown for the first time that SELENBP1 is expressed in both normal ovaries and ovarian tumors in the hen and that SELENBP1 expression is altered in the vicinity of the tumor. Furthermore, SELENBP1 expression in normal ovarian surface epithelium and in ovarian tumors parallels that previously reported for ovarian cancer in women.

Identification of a differentially-expressed gene in fatty liver of overfeeding geese.

In response to overfeeding, geese develop fatty liver. To understand the fattening mechanism, mRNA differential display reverse transcription PCR was used to study the gene expression differences between French Landes grey geese and Xupu white geese in conditions of overfeeding and normal feeding. One gene was found to be up-regulated in the fatty liver in both breeds, and it has a 1797 bp cDNA with 83% identity to chicken SELENBP1. The sequence analysis revealed that its open reading frame of 1413 bp encodes a protein of 471 amino acids, which contains a putative conserved domain of 56 kDa selenium binding protein with high homology to its homologues of chicken (95%), rat (86%), mouse (84%), human (86%), monkey (86%), dog (86%), and cattle (86%). The function of this protein has been briefly reviewed based on published information. In tissue expression analysis, the expression of geese SELENBP1 mRNA was found to be higher in liver or kidney than in other tested tissues. The results showed that overfeeding could increase the mRNA expression level of geese SELENBP1.

Selenium-binding protein 2, the major hepatic target for acetaminophen, shows sex differences in protein abundance.

Liver samples from female and male mice of two subspecies, Mus musculus musculus and Mus musculus domesticus, were investigated by a combination of 2-DE and MALDI-MS. The image analysis of the generated 2-DE patterns revealed several protein spots with significant differences in intensity/abundance between the sexes. Seven protein spots, which were prominent in 2-DE patterns of male mice, but which showed very low intensities in females, were identified as selenium-binding protein 2 (SBP2) also known as 56-kDa acetaminophen-binding protein. Edman degradation indicated that at least three of these protein spots represent N-terminally truncated SBP2 variants. Furthermore, it was shown that the observed differences in SBP2 abundance correlate with sex differences in transcription of the gene encoding SBP2, selenbp2, as revealed by RT-PCR and restriction digest as well as sequence analysis of the products. Since SBP2 has been described as the major target for acetaminophen in mouse liver cytosol, these findings are discussed with respect to their possible relevance for sex differences in acetaminophen-mediated toxicity, which have been described in a variety of mammals including mice and rats.

Selenium binding protein 1 in ovarian cancer.

Selenium binding protein 1 (SELENBP1) was identified to be the most significantly down-regulated protein in ovarian cancer cells by a membrane proteome profiling analysis. SELENBP1 expression levels in 4 normal ovaries, 8 benign ovarian tumors, 12 borderline ovarian tumors and 141 invasive ovarian cancers were analyzed with immunohistochemical assay. SELENBP1 expression was reduced in 87% cases of invasive ovarian cancer (122/141) and was significantly reduced in borderline tumors and invasive cancers (p<0.001). Cox multivariate analysis within the 141 invasive cancer tissues showed that SELENBP1 expression score was a potential prognostic indicator for unfavorable prognosis of ovarian cancer (hazard ratio [HR], 2.18; 95% CI=1.22-3.90; p=0.009). Selenium can disrupt the androgen pathway, which has been implicated in modulating SELENBP1 expression. We investigated the effects of selenium and androgen on normal human ovarian surface epithelial (HOSE) cells and cancer cells. Interestingly, SELENBP1 mRNA and protein levels were reduced by androgen and elevated by selenium treatment in the normal HOSE cells, whereas reversed responses were observed in the ovarian cancer cell lines. These results suggest that changes of SELENBP1 expression in malignant ovarian cancer are an indicator of aberration of selenium/androgen pathways and may reveal prognostic information of ovarian cancer.