SEL1L expression in pancreatic adenocarcinoma parallels SMAD4 expression and delays tumor growth in vitro and in vivo

A glycosylation-related signature predicts survival in pancreatic cancer

BACKGROUND

Tumor initiation and progression are closely associated with glycosylation. However, glycosylated molecules have not been the subject of extensive studies as prognostic markers for pancreatic cancer. The objectives of this study were to identify glycosylation-related genes in pancreatic cancer and use them to construct reliable prognostic models.

MATERIALS AND METHODS

The Cancer Genome Atlas and Gene Expression Omnibus databases were used to assess the differential expression of glycosylation-related genes; four clusters were identified based on consistent clustering analysis. Kaplan-Meier analyses identified three glycosylation-related genes associated with overall survival. LASSO analysis was then performed on The Cancer Genome Atlas and International Cancer Genome Consortium databases to identify glycosylation-related signatures. We identified 12 GRGs differently expressed in pancreatic cancer and selected three genes (SEL1L, TUBA1C, and SDC1) to build a prognostic model. Thereafter, patients were divided into high and low-risk groups. Eventually, we performed Quantitative real-time PCR (qRT-PCR) to validate the signature.

RESULTS

Clinical outcomes were significantly poorer in the high-risk group than in the low-risk group. There were also significant correlations between the high-risk group and several risk factors, including no-smoking history, drinking history, radiotherapy history, and lower tumor grade. Furthermore, the high-risk group had a higher proportion of immune cells. Eventually, three glycosylation-related genes were validated in human PC cell lines.

CONCLUSION

This study identified the glycosylation-related signature for pancreatic cancer. It is an effective predictor of survival and can guide treatment decisions.

EpiMC: Detecting Epistatic Interactions Using Multiple Clusterings

Detecting single nucleotide polymorphisms (SNPs) interactions is crucial to identify susceptibility genes associated with complex human diseases in genome-wide association studies. Clustering-based approaches are widely used in reducing search space and exploring potential relationships between SNPs in epistasis analysis. However, these approaches all only use a single measure to filter out nonsignificant SNP combinations, which may be significant ones from another perspective. In this paper, we propose a two-stage approach named EpiMC (Epistatic Interactions detection based on Multiple Clusterings) that employs multiple clusterings to obtain more precise candidate sets and more comprehensively detect high-order interactions based on these sets. In the first stage, EpiMC proposes a matrix factorization based multiple clusterings algorithm to generate multiple diverse clusterings, each of which divide all SNPs into different clusters. This stage aims to reduce the chance of filtering out potential candidates overlooked by a single clustering and groups associated SNPs together from different clustering perspectives. In the next stage, EpiMC considers both the single-locus effects and interaction effects to select high-quality disease associated SNPs, and then uses Jaccard similarity to get candidate sets. Finally, EpiMC uses exhaustive search on the obtained small candidate sets to precisely detect epsitatic interactions. Extensive simulation experiments show that EpiMC has a better performance in detecting high-order interactions than state-of-the-art solutions. On the Wellcome Trust Case Control Consortium (WTCCC) dataset, EpiMC detects several significant epistatic interactions associated with breast cancer (BC) and age-related macular degeneration (AMD), which again corroborate the effectiveness of EpiMC.

SEL1L plays a major role in human malignant gliomas

Suppressor of Lin-12-like (C. elegans) (SEL1L) participates in the endoplasmic reticulum-associated protein degradation pathway, malignant transformation and stem cell biology. We explored the role of SEL1L in 110 adult gliomas, of different molecular subtype and grade, in relation to cell proliferation, stemness, glioma-associated microglia/macrophages (GAMs), prognostic markers and clinical outcome. SEL1L protein expression was assessed by immunohistochemistry and Western blotting. Genetic and epigenetic alterations were detected by molecular genetics techniques. SEL1L was overexpressed in anaplastic gliomas (World Health Organization [WHO] grade III) and in glioblastoma (GB, WHO grade IV) with the highest labelling index (LI) in the latter. Immunoreactivity was significantly associated with histological grade (p = 0.002) and cell proliferation index Ki-67/MIB-1 (p = 0.0001). In GB, SEL1L co-localised with stemness markers Nestin and Sox2. Endothelial cells and vascular pericytes of proliferative tumour blood vessels expressed SEL1L suggesting a role in tumour neo-vasculature. GAMs consistently expressed SEL1L. SEL1L overexpression was significantly associated with TERT promoter mutations (p = 0.0001), EGFR gene amplification (p = 0.0013), LOH on 10q (p = 0.0012) but was mutually exclusive with IDH1/2 mutations (p = 0.0001). SEL1L immunoreactivity correlated with tumour progression and cell proliferation, conditioning poor patient survival and response to therapy. This study emphasises SEL1L as a potential biomarker for the most common subgroup of TERT mutant/EGFR amplified/IDH-WT GBs.

LAMC1 is a prognostic factor and a potential therapeutic target in endometrial cancer

OBJECTIVE

With the emerging significance of genetic profiles in the management of endometrial cancer, the identification of tumor-driving genes with prognostic value is a pressing need. The LAMC1 gene, encoding the laminin subunit gamma 1 (LAMC1) protein, has been reported to be involved in the progression of various malignant tumors. In this study, we aimed to investigate the role of LAMC1 in endometrial cancer and elucidate the underlying mechanism.

METHODS

We evaluated the immunohistochemical expression of LAMC1 in atypical endometrial hyperplasia and endometrial cancer. Within the endometrial cancer cases, we analyzed the association of LAMC1 overexpression with clinicopathological factors and prognosis. Furthermore, to indentify genes influenced by LAMC1 overexpression, we transfected HEC50B and SPAC-S cells with siRNA targeting LAMC1 and conducted microarray gene expression assays.

RESULTS

While none of the atypical endometrial hyperplasia specimens exhibited LAMC1 overexpression, endometrial cancer possessed a significantly higher LAMC1 overexpression rate. LAMC1 overexpression was strongly associated with histological type, lymphovascular space invasion, lymph node metastasis, advanced International Federation of Gynecology and Obstetrics stage, and poor overall survival in endometrial cancer. Gene expression microarray analysis identified 8 genes correlated with tumor progression (LZTFL1, TAPT1, SEL1L, PAQR6, NME7, TMEM109, CCDC58, and ANKRD40) that were commonly influenced in HEC50B and SPAC-S by LAMC1 silencing.

CONCLUSION

LAMC1 overexpression is a potent biomarker for identifying endometrial cancer patients needing aggressive adjuvant therapy. We elucidated 8 candidate genes that may mediate progression of LAMC1 overexpressing cancer. Further investigation of the underlying mechanism should lead to the discovery of new therapeutic targets.

Identification of genetic variants predictive of early onset pancreatic cancer through a population science analysis of functional genomic datasets

Biomarkers are critically needed for the early detection of pancreatic cancer (PC) are urgently needed. Our purpose was to identify a panel of genetic variants that, combined, can predict increased risk for early-onset PC and thereby identify individuals who should begin screening at an early age. Previously, we identified genes using a functional genomic approach that were aberrantly expressed in early pathways to PC tumorigenesis. We now report the discovery of single nucleotide polymorphisms (SNPs) in these genes associated with early age at diagnosis of PC using a two-phase study design. In silico and bioinformatics tools were used to examine functional relevance of the identified SNPs. Eight SNPs were consistently associated with age at diagnosis in the discovery phase, validation phase and pooled analysis. Further analysis of the joint effects of these 8 SNPs showed that, compared to participants carrying none of these unfavorable genotypes (median age at PC diagnosis 70 years), those carrying 1–2, 3–4, or 5 or more unfavorable genotypes had median ages at diagnosis of 64, 63, and 62 years, respectively (P = 3.0E–04). A gene-dosage effect was observed, with age at diagnosis inversely related to number of unfavorable genotypes (P_trend = 1.0E–04). Using bioinformatics tools, we found that all of the 8 SNPs were predicted to play functional roles in the disruption of transcription factor and/or enhancer binding sites and most of them were expression quantitative trait loci (eQTL) of the target genes. The panel of genetic markers identified may serve as susceptibility markers for earlier PC diagnosis.

mSEL-1L deficiency affects vasculogenesis and neural stem cell lineage commitment

mSEL-1L is a highly conserved ER-resident type I protein, involved in the degradation of misfolded peptides through the ubiquitin-proteasome system (UPS), a pathway known to control the plasticity of the vascular smooth muscle cells (VSMC) phenotype and survival. In this article, we demonstrate that mSEL-1L deficiency interferes with the murine embryonic vascular network, showing particular irregularities in the intracranic and intersomitic neurovascular units and in the cerebral capillary microcirculation. During murine embryogenesis, mSEL-1L is expressed in cerebral areas known to harbor progenitor neural cells, while in the adult brain the protein is specifically restricted to the stem cell niches, co-localizing with Sox2 and Nestin. Null mice are characterized by important defects in the development of telenchephalic regions, revealing conspicuous aberration in neural stem cell lineage commitment. Moreover, mSEL-1L depletion in vitro and in vivo appears to affect the harmonic differentiation of the NSCs, by negatively influencing the corticogenesis processes. Overall, the data presented suggests that the drastic phenotypic characteristics exhibited in mSEL-1L null mice can, in part, be explained by the negative influence it plays on Notch1 signaling pathway.

SEL1L SNP rs12435998, a predictor of glioblastoma survival and response to radio-chemotherapy

The suppressor of Lin-12-like (C. elegans) (SEL1L) is involved in the endoplasmic reticulum (ER)-associated degradation pathway, malignant transformation and stem cells.

In 412 formalin-fixed and paraffin-embedded brain tumors and 39 Glioblastoma multiforme (GBM) cell lines, we determined the frequency of five SEL1L single nucleotide genetic variants with regulatory and coding functions by a SNaPShot™ assay. We tested their possible association with brain tumor risk, prognosis and therapy.

We studied the in vitro cytotoxicity of valproic acid (VPA), temozolomide (TMZ), doxorubicin (DOX) and paclitaxel (PTX), alone or in combination, on 11 GBM cell lines, with respect to the SNP rs12435998 genotype.

The SNP rs12435998 was prevalent in anaplastic and malignant gliomas, and in meningiomas of all histologic grades, but unrelated to brain tumor risks. In GBM patients, the SNP rs12435998 was associated with prolonged overall survival (OS) and better response to TMZ-based radio-chemotherapy. GBM stem cells with this SNP showed lower levels of SEL1L expression and enhanced sensitivity to VPA.

Down-modulation of SEL1L, an unfolded protein response and endoplasmic reticulum-associated degradation protein, sensitizes glioma stem cells to the cytotoxic effect of valproic acid

Valproic acid (VPA), an histone deacetylase inhibitor, is emerging as a promising therapeutic agent for the treatments of gliomas by virtue of its ability to reactivate the expression of epigenetically silenced genes. VPA induces the unfolded protein response (UPR), an adaptive pathway displaying a dichotomic yin yang characteristic; it initially contributes in safeguarding the malignant cell survival, whereas long-lasting activation favors a proapoptotic response. By triggering UPR, VPA might tip the balance between cellular adaptation and programmed cell death via the deregulation of protein homeostasis and induction of proteotoxicity. Here we aimed to investigate the impact of proteostasis on glioma stem cells (GSC) using VPA treatment combined with subversion of SEL1L, a crucial protein involved in homeostatic pathways, cancer aggressiveness, and stem cell state maintenance. We investigated the global expression of GSC lines untreated and treated with VPA, SEL1L interference, and GSC line response to VPA treatment by analyzing cell viability via MTT assay, neurosphere formation, and endoplasmic reticulum stress/UPR-responsive proteins. Moreover, SEL1L immunohistochemistry was performed on primary glial tumors. The results show that (i) VPA affects GSC lines viability and anchorage-dependent growth by inducing differentiative programs and cell cycle progression, (ii) SEL1L down-modulation synergy enhances VPA cytotoxic effects by influencing GSCs proliferation and self-renewal properties, and (iii) SEL1L expression is indicative of glioma proliferation rate, malignancy, and endoplasmic reticulum stress statuses. Targeting the proteostasis network in association to VPA treatment may provide an alternative approach to deplete GSC and improve glioma treatments.

Putative tumor suppressor gene SEL1L was downregulated by aberrantly upregulated hsa-mir-155 in human pancreatic ductal adenocarcinoma

Sel-1-like (SEL1L) is a putative tumor suppressor gene that is significantly downregulated in human pancreatic ductal adenocarcinoma (PDA). The mechanism of the downregulation is unclear. Here, we investigated whether aberrantly upregulated microRNAs (miRNAs) repressed the expression of SEL1L. From reported miRNA microarray studies on PDA and predicted miRNA targets, we identified seven aberrantly upregulated miRNAs that potentially target SEL1L. We assessed the expression levels of SEL1L mRNA and the seven miRNAs in human PDA tumors and normal adjacent tissues using real-time quantitative polymerase chain reaction. Then statistical methods were applied to evaluate the association between SEL1L mRNA and the miRNAs. Furthermore, the interaction was explored by functional analysis, including luciferase assay and transient miRNA overexpression. SEL1L mRNA expression levels were found to correlate inversely with the expression of hsa-mir-143, hsa-mir-155, and hsa-mir-223 (P < 0.0001, P < 0.0001, and P = 0.002, respectively). As the number of these overexpressed miRNAs increased, SEL1L mRNA expression progressively decreased (Ptrend  = 0.001). Functional analysis revealed that hsa-mir-155 acted as a suppressor of SEL1L in PDA cell lines. Our study combined statistical analysis with biological approaches to determine the relationships between several miRNAs and the SEL1L gene. The finding that the expression of the putative tumor suppressor SEL1L is repressed by upregulation of hsa-mir-155 helps to elucidate the mechanism for SEL1L downregulation in some human PDA cases. Our results suggest a role for specific miRNAs in the pathogenesis of PDA and indicate that miRNAs have potential as therapeutic targets for PDA.

Cell and tissue microarray technologies for protein and nucleic acid expression profiling

Tissue microarray (TMA) and cell microarray (CMA) are two powerful techniques that allow for the immunophenotypical characterization of hundreds of samples simultaneously. In particular, the CMA approach is particularly useful for immunophenotyping new stem cell lines (e.g., cardiac, neural, mesenchymal) using conventional markers, as well as for testing the specificity and the efficacy of newly developed antibodies. We propose the use of a tissue arrayer not only to perform protein expression profiling by immunohistochemistry but also to carry out molecular genetics studies. In fact, starting with several tissues or cell lines, it is possible to obtain the complete signature of each sample, describing the protein, mRNA and microRNA expression, and DNA mutations, or eventually to analyze the epigenetic processes that control protein regulation. Here we show the results obtained using the Galileo CK4500 TMA platform.

Molecular chaperones as therapeutic targets to counteract proteostasis defects

The health of cells is preserved by the levels and correct folding states of the proteome, which is generated and maintained by the proteostasis network, an integrated biological system consisting of several cytoprotective and degradative pathways. Indeed, the health conditions of the proteostasis network is a fundamental prerequisite to life as the inability to cope with the mismanagement of protein folding arising from genetic, epigenetic, and micro-environment stress appears to trigger a whole spectrum of unrelated diseases. Here we describe the potential functional role of the proteostasis network in tumor biology and in conformational diseases debating on how the signaling branches of this biological system may be manipulated to develop more efficacious and selective therapeutic strategies. We discuss the dual strategy of these processes in modulating the folding activity of molecular chaperones in order to counteract the antithetic proteostasis deficiencies occurring in cancer and loss/gain of function diseases. Finally, we provide perspectives on how to improve the outcome of these disorders by taking advantage of proteostasis modeling.

SEL1L, an UPR response protein, a potential marker of colonic cell transformation

BACKGROUND

SEL1L gene product is implicated in the endoplasmic reticulum (ER)-associated protein degradation and Unfolded Protein Response pathways. This gene and associated miRNAs have been indicated as predictive and prognostic markers of pancreatic cancer.

AIM

Explore the role of SEL1L in colorectal cancer (CRC) progression.

METHODS

SEL1L expression was analysed immunohistochemically in 153 adenomas and 71 CRCs from African American and North Italian patients. The distribution of stained cells was determined by computing median and inter quartile range. The receiver operating characteristics plot was used as discriminate power of SEL1L expression, CRC diagnosis and the effects on patient survival.

RESULTS

SEL1L was low in normal mucosa and confined to few scattered cells at the base crypt of the villi and in the foveolar glandular compartment. The highest levels were in Paneth cells within the lysosomes. The enterocytic progenitor cells and mature enterocytes showed less cytoplasmic staining. In CRCs, SEL1L expression significantly correlated with the progression from adenoma to carcinoma (P = 0.0001) being stronger in well-to-moderately differentiated cancers. No correlation was found with other clinicopathological characteristics or ethnicity.

CONCLUSIONS

SEL1L expression is a potential CRC tissue biomarker since its expression is significantly higher in adenoma cells with respect to normal mucosa. The levels of expression decrease sensibly in undifferentiated CRC cancers. Interestingly, Paneth cells contain high levels of SEL1L protein that could indicate pre-neoplastic mucosa undergoing neoplastic transformation. Since SEL1L's major function lies within ER stress and active ERAD response, it may identify CRCs with differentiated secretory phenotype and acute cellular stress.

Recognition of host proteins by Helicobacter cysteine-rich protein C

Tetratricopeptide- and sel1-like repeat (SLR) proteins modulate various cellular activities, ranging from transcription regulation to cell-fate control. Helicobacter cysteine-rich proteins (Hcp) consist of several SLRs that are cross-linked by disulfide bridges and have been implicated in host/pathogen interactions. Using pull-down proteomics, several human proteins including Nek9, Hsp90, and Hsc71 have been identified as putative human interaction partners for HcpC. The interaction between the NimA-like protein kinase Nek9 and HcpC has been validated by ELISA and surface plasmon resonance. Recombinant Nek9 is recognized by HcpC with a dissociation constant in the lower micromolar range. This interaction is formed either directly between Nek9 and HcpC or via the formation of a complex with Hsc71. The HcpC homologue HcpA possesses no affinity for Nek9, suggesting that the reported interaction is rather specific for HcpC. These results are consistent with previous observations where Nek9 was targeted upon bacterial or viral invasion. However, further experiments will be required to show that the reported interactions also occur in vivo.

A single-nucleotide polymorphism in tumor suppressor gene SEL1L as a predictive and prognostic marker for pancreatic ductal adenocarcinoma in Caucasians

SEL1L is a putative tumor suppressor gene that is frequently down-regulated in pancreatic ductal adenocarcinoma (PDA). A single-nucleotide polymorphism (SNP) rs12435998 in intron3 of SEL1L has previously been reported to be associated with susceptibility to Alzheimer's disease. We hypothesized that this SNP may influence clinical outcomes of patients with PDA. We analyzed DNA samples from 497 Caucasian patients with pathologically confirmed primary PDA. Of these, 98 had been enrolled in a clinical trial of neoadjuvant chemo-radiotherapy and 77 of the 98 had subsequently undergone pancreaticoduodenectomy (PD). We performed Kaplan-Meier analysis to evaluate the correlation between different SNP genotypes and age at diagnosis, survival time after diagnosis, and survival time after PD. In nonsmokers, we found a significant difference in median age at diagnosis between variant genotypes (AG/GG) carriers and wild-type genotype (AA) carriers (58 vs. 62 yr; log-rank test, P = 0.017). Patients with variant genotypes also showed an increased hazard ratio (HR) of 1.45 [95% confidence interval (CI), 1.07-1.97] relative to wild-type genotype. Among the patients in the clinical trial, the variant genotypes carriers had a median post-PD survival time that was 34.7 months shorter than wild-type genotype carriers (log-rank test, P = 0.019; HR, 1.91; 95% CI, 1.09-3.34). Our results suggest that the rs12435998 SNP in SEL1L gene plays a role in modifying age at diagnosis of PDA in Caucasian nonsmokers. In addition, this SNP may serve as a prognostic marker in PDA patients who undergo the same or similar treatment as the clinical trials.

Secretion of novel SEL1L endogenous variants is promoted by ER stress/UPR via endosomes and shed vesicles in human cancer cells

We describe here two novel endogenous variants of the human endoplasmic reticulum (ER) cargo receptor SEL1LA, designated p38 and p28. Biochemical and RNA interference studies in tumorigenic and non-tumorigenic cells indicate that p38 and p28 are N-terminal, ER-anchorless and more stable relative to the canonical transmembrane SEL1LA. P38 is expressed and constitutively secreted, with increase after ER stress, in the KMS11 myeloma line and in the breast cancer lines MCF7 and SKBr3, but not in the non-tumorigenic breast epithelial MCF10A line. P28 is detected only in the poorly differentiated SKBr3 cell line, where it is secreted after ER stress. Consistently with the presence of p38 and p28 in culture media, morphological studies of SKBr3 and KMS11 cells detect N-terminal SEL1L immunolabeling in secretory/degradative compartments and extracellularly-released membrane vesicles. Our findings suggest that the two new SEL1L variants are engaged in endosomal trafficking and secretion via vesicles, which could contribute to relieve ER stress in tumorigenic cells. P38 and p28 could therefore be relevant as diagnostic markers and/or therapeutic targets in cancer.

A migration signature and plasma biomarker panel for pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma is a disease of extremely poor prognosis for which there are no reliable markers of asymptomatic disease. To identify pancreatic cancer biomarkers, we focused on a genomic interval proximal to the most common fragile site in the human genome, chromosome 3p12, which undergoes smoking-related breakage, loss of heterozygosity, and homozygous deletion as an early event in many epithelial tumors, including pancreatic cancers. Using a functional genomic approach, we identified a seven-gene panel (TNC, TFPI, TGFBI, SEL-1L, L1CAM, WWTR1, and CDC42BPA) that was differentially expressed across three different expression platforms, including pancreatic tumor/normal samples. In addition, Ingenuity Pathways Analysis (IPA) and literature searches indicated that this seven-gene panel functions in one network associated with cellular movement/morphology/development, indicative of a "migration signature" of the 3p pathway. We tested whether two secreted proteins from this panel, tenascin C (TNC) and tissue factor pathway inhibitor (TFPI), could serve as plasma biomarkers. Plasma ELISA assays for TFPI/TNC resulted in a combined area under the curve (AUC) of 0.88 and, with addition of CA19-9, a combined AUC for the three-gene panel (TNC/TFPI/CA19-9), of 0.99 with 100% specificity at 90% sensitivity and 97.22% sensitivity at 90% specificity. Validation studies using TFPI only in a blinded sample set increased the performance of CA19-9 from an AUC of 0.84 to 0.94 with the two-gene panel. Results identify a novel 3p pathway-associated migration signature and plasma biomarker panel that has utility for discrimination of pancreatic cancer from normal controls and promise for clinical application.

Differential proteomics in the aging Noble rat ventral prostate

Incidence of prostatic diseases increases dramatically with age which may be related to a decline in androgen support. However, the key mechanisms underlying prostate aging remain unclear. In the present study, we investigated the aging process in the ventral prostate (VP) of Noble rats by identifying differentially expressed prostate proteins between 3- and 16-month-old animals using ICAT and MS. In total, 472 proteins were identified with less than a 1% false positive rate, among which 34 were determined to have a greater than two-fold increase or 1.7-fold decrease in expression in the aged VPs versus their younger counterparts. The majority of the differentially expressed proteins identified have not been previously reported to be associated with prostate aging, and they fall into specific functional categories, including oxidative stress/detoxification, chaperones, protein biosynthesis, vesicle transport, and intracellular trafficking. The expression of GST, ferritin, clusterin, kininogen, oxygen regulated protein 150, spermidine synthase, ADP ribosylation factor, and cyclophilin B was verified by Western blot analyses on samples used for the ICAT study, as well as on those obtained from an independent group of animals comprised of three age groups. To the best of our knowledge, this is the first study on the proteome of the aging rat prostate.

Recurring translocation (10;17) and deletion (14q) in clear cell sarcoma of the kidney

CONTEXT

Clear cell sarcoma of the kidney (CCSK) is a prognostically unfavorable renal neoplasm of childhood. Previous cytogenetic studies of CCSK have reported balanced translocations t(10;17)(q22;p13) and t(10;17)(q11;p12). Although the tumor suppressor gene p53 is located at the chromosome 17p13 breakpoint, p53 abnormalities are rarely present in these tumors.

OBJECTIVE

To identify cytogenetic abnormalities in CCSK and correlate these findings with other clinicopathologic parameters.

DESIGN

A retrospective review of CCSK patients from 1990 to 2005 was conducted at our medical center. We performed clinical and histologic review, p53 immunohistochemical and classic cytogenetics (or ploidy analysis), and p53 fluorescence in situ hybridization analyses.

RESULTS

Five male patients (age range, 6 months to 4 years) were identified with cytogenetic abnormalities. Of 3 cytogenetically informative cases, one revealed a clonal balanced translocation t(10;17)(q22;p13) and an interstitial deletion of chromosome 14, del(14)(q24.1q31.1), and the other 2 patients had normal karyotypes. Fluorescence in situ hybridization for p53 in the t(10;17) case revealed no deletion. Immunohistochemical evaluation of p53 demonstrated lack of nuclear protein accumulation in all cases.

CONCLUSIONS

Together with the published literature, our results indicate that translocation (10;17) and interstitial deletions of chromosome 14q are recurring cytogenetic lesions in CCSK. To date, 3 cases of CCSK or "sarcomatoid Wilms tumors" have been reported to exhibit t(10;17). One previously reported case of CCSK contained deletion 14q. Results of p53 immunohistochemistry and/or p53 fluorescence in situ hybridization in this report suggest lack of mutations or deletions of this tumor suppressor in these CCSK cases. The t(10;17) breakpoint and deletion of chromosome 14q24 suggest that other genes are involved in tumor pathogenesis.

Effect of DPC4 gene on invasion and metastasis of colorectal carcinoma cells

To investigate the effect of DPC4 gene on invasion and metastasis of colorectal carcinoma cells, the expression of DPC4 was detected in sixty-three samples of colorectal tumors and seven cases of colorectal mucosa. The biological behavior of tumors expressing DPC4 was evaluated (including tumor staging, differentiation degree and metastasis). pcDNA3.1-DPC4 plasmid was constructed and transferred into HCT116 cells not expressing DPC4. The cell models (DPC4(+)-HCT116) steadily expressing DPC4 were obtained. Compared with HCT116 and pcDNA3.1-HCT116 cells, the doubling time of DPC4(+)-HCT116 cells was lengthened obviously (P<0.01), the apoptosis rate of DPC4(+)-HCT116 cells was significantly increased (PP<0.01), the cloning efficiency, cell adherency, migration and invasion ability of DPC4+-HCT116 cells were dropped obviously (P<0.01). The number of cancer nodules was decreased significantly in abdominal cavity and liver of the nude mice inoculated with DPC4(+)-HCT116 cells. The activity of MMP-9 and MMP-2 was detected by gelatin zymography. In comparison with HCT116 and pcDNA3.1-HCT116 cells, the activity of MMP-9 was decreased in DPC4(+)-HCT116 cells. Therefore, the down-regulation of DPC4 expression may be associated with the carcinogenesis of colorectal carcinoma. DPC4 may inhibit the proliferation of colon cancer cell by restraining growth and inducing apoptosis, and the invasion and metastasis of colorectal carcinoma cells. MMP-9 may be one of the downstream target genes regulated by DPC4.

Hypoxia induces p53-dependent transactivation and Fas/CD95-dependent apoptosis

p53 triggers apoptosis in response to cellular stress. We analyzed p53-dependent gene and protein expression in response to hypoxia using wild-type p53-carrying or p53 null HCT116 colon carcinoma cells. Hypoxia induced p53 protein levels and p53-dependent apoptosis in these cells. cDNA microarray analysis revealed that only a limited number of genes were regulated by p53 upon hypoxia. Most classical p53 target genes were not upregulated. However, we found that Fas/CD95 was significantly induced in response to hypoxia in a p53-dependent manner, along with several novel p53 target genes including ANXA1, DDIT3/GADD153 (CHOP), SEL1L and SMURF1. Disruption of Fas/CD95 signalling using anti-Fas-blocking antibody or a caspase 8 inhibitor abrogated p53-induced apoptosis in response to hypoxia. We conclude that hypoxia triggers a p53-dependent gene expression pattern distinct from that induced by other stress agents and that Fas/CD95 is a critical regulator of p53-dependent apoptosis upon hypoxia.

SEL1L a multifaceted protein playing a role in tumor progression

Since the cloning in 1997 of SEL1L, the human ortholog of the sel-1 gene of C. elegans, most studies have focused on its role in cancer progression and have provided significant evidences to link its increased expression to a decrease in tumor aggressiveness. SEL1L resides on a "Genome Desert area" on chromosome 14q24.3-31 and is highly conserved in evolution. The function of the SEL1L encoded protein is still very elusive although, several evidences from lower organisms indicate that it plays a major role in protein degradation using the ubiquitin-proteosome system. SEL1L has a very complex structure made up of modules: genomically it consists of 21 exons featuring several alternative transcripts encoding for putative protein isoforms. This structural complexity ensures protein flexibility and specificity, indeed the protein was found in different sub-cellular compartments and may turn on a particular transcript in response to specific stimuli. The overall architecture of SEL1L guarantees an exquisite regulation in the expression of the gene.

Sel1-like repeat proteins in signal transduction

Solenoid proteins, which are distinguished from general globular proteins by their modular architectures, are frequently involved in signal transduction pathways. Proteins from the tetratricopeptide repeat (TPR) and Sel1-like repeat (SLR) families share similar alpha-helical conformations but different consensus sequence lengths and superhelical topologies. Both families are characterized by low sequence similarity levels, rendering the identification of functional homologous difficult. Therefore current knowledge of the molecular and cellular functions of the SLR proteins Sel1, Hrd3, Chs4, Nif1, PodJ, ExoR, AlgK, HcpA, Hsp12, EnhC, LpnE, MotX, and MerG has been reviewed. Although SLR proteins possess different cellular functions they all seem to serve as adaptor proteins for the assembly of macromolecular complexes. Sel1, Hrd3, Hsp12 and LpnE are activated under cellular stress. The eukaryotic Sel1 and Hrd3 proteins are involved in the ER-associated protein degradation, whereas the bacterial LpnE, EnhC, HcpA, ExoR, and AlgK proteins mediate the interactions between bacterial and eukaryotic host cells. LpnE and EnhC are responsible for the entry of L. pneumophila into epithelial cells and macrophages. ExoR from the symbiotic microorganism S. melioti and AlgK from the pathogen P. aeruginosa regulate exopolysaccaride synthesis. Nif1 and Chs4 from yeast are responsible for the regulation of mitosis and septum formation during cell division, respectively, and PodJ guides the cellular differentiation during the cell cycle of the bacterium C. crescentus. Taken together the SLR motif establishes a link between signal transduction pathways from eukaryotes and bacteria. The SLR motif is so far absent from archaea. Therefore the SLR could have developed in the last common ancestor between eukaryotes and bacteria.

SEL1L expression in non-small cell lung cancer

SEL1L gene product plays a role in cell transformation and tumor progression in human breast, pancreas, esophageal, and prostate cancer. SEL1L expression was evaluated in a series of 76 surgically resected non-small cell lung carcinomas to investigate its clinical significance. SEL1L is scarcely detectable in normal lung, whereas in the initial stages of cell transformation, it becomes consistently expressed with evident staining in bronchial squamous metaplasia and in associated dysplastic changes. SEL1L immunoreactivity can be detected both in the cytoplasm and less commonly in the nuclei; the subcellular location correlates with tumor histotype, with cytoplasmic immunoreactivity being most prevalent in squamous cell carcinomas (P = .0005) and nuclear immunoreactivity being associated with adenocarcinomas (P = .02). Nuclear import and export signals are present in the SEL1L coding sequence, justifying the different subcellular location of the protein. SEL1L immunoreactivity was inversely correlated with tumor grade (P = .05); when considering only the adenocarcinomas, a stronger association was found (P = .006). SEL1L messenger RNA and protein evaluation in lung cancer cell lines confirmed the expression of the gene and the dual subcellular location of the protein in lung tumors. The data here reported suggest that, in non-small cell lung carcinoma, SEL1L may be an indicator of cell transformation, thus having important biologic and clinical implications.

The role of the ubiquitination machinery in dislocation and degradation of endoplasmic reticulum proteins

Ubiquitination is essential for the dislocation and degradation of proteins from the endoplasmic reticulum (ER). How exactly this is regulated is unknown at present. This review provides an overview of ubiquitin-conjugating enzymes (E2s) and ubiquitin ligases (E3s) with a role in the degradation of ER proteins. Their structure and functions are described, as well as their mutual interactions. Substrate specificity and functional redundancy of E3 ligases are discussed, and other components of the ER degradation machinery that may associate with the ubiquitination system are reviewed.

SEL1L affects human pancreatic cancer cell cycle and invasiveness through modulation of PTEN and genes related to cell-matrix interactions

Previously, it was reported that SEL1L is able to decrease the aggressive behavior of human pancreatic tumor cells both in vitro and in vivo. To gain insights into the involvement of SEL1L in tumor invasion, we performed gene expression analysis on the pancreatic cancer cell line Suit-2 subjected to two complementary strategies: upregulation and downregulation of SEL1L expression by stable transfection of the entire cDNA under an inducible promoter and by RNA-mediated interference. SuperArray and real-time analysis revealed that SEL1L modulates the expression of the matrix metalloproteinase inhibitors TIMP1 (P < .04-.03) and TIMP2 (P < .03-.05), and the PTEN gene (P < .03-.05). Gene expression modulations correlate with the decrease in invasive ability (P < .05) and in accumulation of SEL1L-expressing cells in G1. Taken together, our data indicate that SEL1L alters the expression of mediators involved in the remodeling of the extracellular matrix by creating a microenvironment that is unfavorable to invasive growth and by affecting cell cycle progression through promotion of G1 accumulation.

Multiprotein complexes that link dislocation, ubiquitination, and extraction of misfolded proteins from the endoplasmic reticulum membrane

Polypeptides that fail to pass quality control in the endoplasmic reticulum (ER) are dislocated from the ER membrane to the cytosol where they are degraded by the proteasome. Derlin-1, a member of a family of proteins that bears homology to yeast Der1p, was identified as a factor that is required for the human cytomegalovirus US11-mediated dislocation of class I MHC heavy chains from the ER membrane to the cytosol. Derlin-1 acts in concert with the AAA ATPase p97 to remove dislocation substrate proteins from the ER membrane, but it is unknown whether other factors aid Derlin-1 in its function. Mammalian genomes encode two additional, related proteins (Derlin-2 and Derlin-3). The similarity of the mammalian Derlin-2 and Derlin-3 proteins to yeast Der1p suggested that these as-yet-uncharacterized Derlins also may play a role in ER protein degradation. We demonstrate here that Derlin-2 is an ER-resident protein that, similar to Derlin-1, participates in the degradation of proteins from the ER. Furthermore, we show that Derlin-2 forms a robust multiprotein complex with the p97 AAA ATPase as well as the mammalian orthologs of the yeast Hrd1p/Hrd3p ubiquitin-ligase complex. The data presented here define a set of interactions between proteins involved in dislocation of misfolded polypeptides from the ER.

Protein profile changes in the human breast cancer cell line MCF-7 in response toSEL1L gene induction

The ectopic expression of the gene SEL1L in the human breast carcinoma cell line MCF-7 resulted in a reduction of the aggressive behaviour of these cells in vitro. In addition, in vivo analysis on a series of primary breast carcinomas revealed an association between the SEL1L protein levels and the patient's overall survival. We aimed to find those proteins, associated with SEL1L, which may be involved in modulating the aggressive or invasive behaviour of breast cancer cells. For this purpose, we used both the proteomic and microarray approaches. Image analysis of two-dimensional electropherograms revealed the presence of 27 qualitative and 35 quantitative variations between the MCF7-SEL1L expressing cells compared to control. Mass spectrometry identified 32 changing proteins mostly involved in cytoskeletal and metabolic activities, stress response and protein folding, selenoprotein synthesis and cellular proliferation. Five of these also showed changes in transcript levels, as assessed by Affymetrix microarray analysis. Interestingly, seven proteins: carbonic anhydrase (CA) II, ovarian/breast septin, S100A16 calcium binding protein, 14-3-3 protein sigma, proteasome subunit beta type 6, Hsp60 and protein disulphide-isomerase A3 merit particular attention since they are known to be involved in cancer, in response to cellular stress and in protein folding.

Identification of proteins released by pancreatic cancer cells by multidimensional protein identification technology: a strategy for identification of novel cancer markers

The purpose of this study is to identify novel proteins released by cancer cells that are involved in extracellular matrix (ECM) remodeling using small-volume samples and automated technology. We applied multidimensional protein identification technology (MudPIT), which incorporates two-dimensional capillary chromatography coupled to tandem mass spectrometry to small quantities of serum-free supernatants of resting or phorbol ester-activated Suit-2 pancreatic cancer cells. Selected markers were validated in additional pancreatic cancer cell lines, primary cancers, and xenografted cancer cells. MudPIT analysis of 10 microl of supernatants identified 46 proteins, 21 of which are classified as secreted, and 10 have never been associated with pancreatic cancer. These include CSPG2/versican, Mac25/angiomodulin, IGFBP-1, HSPG2/perlecan, syndecan 4, FAM3C, APLP2, cyclophilin B, beta2 microglobulin, and ICA69. Evidence that cancer cells release these proteins in vivo was obtained for CSPG2/versican and Mac25/angiomodulin by immunohistochemistry on both primary pancreatic cancers and in a model consisting of Suit-2 cells embedded in an amorphous matrix and implanted in athymic mice. MudPIT allowed efficient and rapid identification of proteins released by cancer cells, including molecules previously undescribed in the type of cancer analyzed. Our finding that pancreatic cancer cells secrete a series of proteoglycans, including versican, perlecan, syndecan 1 and 4, challenges the common view that fibroblasts of tumor stroma are the sole source of these molecules.

SEL1L and squamous cell carcinoma of the esophagus

The gene SEL1L is involved both in human breast and pancreatic cancer progression. It is located on 14q24.3-31, a region known to be lost in invasive cancer of the esophagus. We aimed to assess whether SEL1L could become a useful biomarker for this cancer. We assessed SEL1L mRNA and protein expression in 35 patients and found it to be weak in low-grade and strong in high-grade dysplasia. Although the majority of cancer patients showed differential expression (mRNA and protein) of SEL1L, in five cases it was completely absent; these patients had the worst outcomes. SEL1L immunoreactivity was negative in normal tissue samples from five patients with mild esophagitis as well as in normal mucosa adjacent to the tumor. We hypothesize that SEL1L could influence those cellular changes that mediate the transition from a normal mucosa to a neoplastic lesion and may help in the identification of those patients at higher risk of developing this cancer. The specific impact of SEL1L in esophageal cancer needs further investigation.

Effect of deleted pancreatic cancer locus 4 gene transfection on biological behaviors of human colorectal carcinoma cells

AIM: To investigate the effect of deleted pancreatic cancer locus 4 (DPC4) gene transfection on biological behaviors of human colorectal carcinoma cells and the role of DPC4 gene in colorectal carcinogenesis.

METHODS: PcDNA3.1-DPC4 plasmid was re-constructed by gene-recombination technology. SW620 cells, a human colorectal carcinoma cell line, were transfected with PcDNA3.1-DPC4 plasmid using lipofectamine transfecting technique. Transfected cells were selected with G418. Expression of Smad4 protein was detected in cells transfected with DPC4 gene by immunohistochemistry and Western blot. Biological characteristics of transfected cells were evaluated by population-doubling time and cloning efficiency. Alterations of percentage of S phage cells (S%) and apoptosis rate were determined by flow- cytometry.

RESULTS: PcDNA3.1-DPC4 plasmid was constructed successfully. SW620 cells transfected with PcDNA3.1-DPC4 plasmid (DPC4⁺-SW620 cells) showed a strong intracellular expression of Smad4 protein, and the positive signal was localized in cytoplasm and nuclei, mainly in cytoplasm, where the expressions of Smad4 protein in SW620 cells transfected with PcDNA3.1 plasmid (PcDNA3.1-SW620 cells) and non-transfected SW620 cells (SW620 cells) were weaker than those in DPC4⁺-SW620 cells. The population- doubling time in DPC4⁺-SW620 cells (116 h) was significantly longer than that in SW620 cells (31 h) and PcDNA3.1-Sw620 cells (29 h) (P<0.01). The cloning efficiencies of DPC4⁺-SW620 cells (12%) were markedly lower than those of SW620 cells (69%) and PcDNA3.1-Sw620 cells (67%) (P<0.01). Compared with SW620 cells and PcDNA3.1-Sw620 cells, the G₀-G₁% of DPC4⁺-SW620 cells was obviously higher and the S% was markedly lower (P<0.05). Apoptosis rate of DPC4⁺-SW620 cells was significantly higher than that of SW620 cells and PcDNA3.1-SW620 cells.

CONCLUSION: PcDNA3.1-DPC4 plasmid can be successfully re-constructed and stably transfected into human SW620 cells, thereby the cells can steadily express Smad4. DPC4 protein may regulate proliferation of colorectal carcinoma cells by inhibiting cell growth and inducing cell apoptosis.

RNA-mediated interference indicates that SEL1L plays a role in pancreatic beta-cell growth

The specificity of SEL1L expression and promoter activity for the pancreatic cell population, its chromosomal location, as well as its similarities to the yeast Hrd3p protein, a component of HRD complex which is responsible for endoplasmic reticulum (ER)-associated degradation of numerous ER-resident proteins, prompted us to study its effects on beta cell function. In this study we show that lowering SEL1L expression, by using the short interfering RNAs technology as well as antisense transfection, resulted in severe perturbation of betaTC-3 growth and metabolic activity. We hypothesize that SEL1L may exert its function by protecting the cells from ER stress and could counteract immune responses.

Expression and significance of Smad4 in colorectal carcinoma tissue

AIM: To investigate the role of Smad4 protein in colorectal carcinogenesis.

METHODS: Expression of Smad4 was detected in 70 cases of normal tissues and colorectal tumor by a streptavidin-peroxidase conjugation method (S-P).

RESULTS: Smad4 expression was significantly lower in colorectal carcinoma (n = 52) than that in the normal tissues (n = 7) and was related to the tumor stages, differentiation and metastasis (lymph node or blood) (P < 0.05).

CONCLUSION: Down-regulation of Smad4 expression may be associated with the carcinogenesis, and Smad4 may play a role in invasion and metastasis of colorectal carcinoma.

Identification of a region within SEL1L protein required for tumour growth inhibition

The ectopic expression of the entire SEL1L cDNA significantly reduces the proliferate activity and aggressive behavior of the human breast carcinoma cell line MCF-7. However, the mechanism responsible for this biological effect remains unclear. A study was initiated to define those regions within SEL1L conferring such antiproliferative properties. Here we report that the region between amino acid residues 659-794 contains a functionally relevant domain since a deletion mutant impairs SEL1L's ability to suppress tumor cell growth. This region contains the Hrd3 motif, tetratricopeptide (TPR)-like SEL1 repeat, a transmembrane region, and a proline-rich tail.