Cloning of TC-1 (C8orf4), a novel gene found to be overexpressed in thyroid cancer

Autophagy-prominent cell clusters among human lens epithelial cells: integrated single-cell RNA-sequencing analysis

BACKGROUND

Autophagy is an important process that maintains the quality of intracellular proteins and organelles. There is extensive evidence that autophagy has an important role in the lens. Human lens epithelial cells (HLECs) play a key role in the internal homeostasis of the lens. HLEC subtypes have been identified, but autophagy-prominent cell clusters among HLECs have not been characterized.

PURPOSE

To explore the existence of autophagy-prominent cell clusters in HLECs.

METHODS

Three donated lenses (HLECs from two whole lenses and HLECs from one lens without the anterior central 6-mm zone) were used for single-cell RNA sequencing (scRNA-seq). AUCell and AddModuleScore analysis were used to identify potential autophagy-prominent cell clusters. Transmission electron microscopy (TEM) was used to confirm the results.

RESULTS

High-quality transcripts from 18,120 cells were acquired by scRNA-seq of the two intact lenses. Unsupervised clustering classified the cells into four clusters. AUCell and AddModuleScore analysis revealed cluster 1 is autophagy-prominent. scRNA-seq analysis of HLECs from the lens capsule lacking the central zone confirmed the cluster 1 HLECs was located in the central capsule zone. The TEM result showed that greater autophagy activity was observed in the HLECs in central capsule zone, which further supported the above conclusions based on scRNA-seq analysis that autophagy was prominent in the central zone where the cluster 1 HLECs located.

CONCLUSIONS

We identified an autophagy-prominent cell cluster among HLECs and revealed that it was localized in the central zone of the lens capsule. Our findings will aid investigations of autophagy in HLECs and provide insights to guide related research.

Association of C8orf4 expression with its methylation status, aberrant β-catenin expression, and the development of cervical squamous cell carcinoma

Chromosome 8 open reading frame 4 (C8orf4) is an activator of Wnt signaling pathway, and participates in the tumorigenesis and progression of many tumors. The expression levels of C8orf4 and β-catenin were assessed via immunohistochemical staining in 100 cervical squamous cell carcinoma (CSCC) tissues, 50 high-grade squamous intraepithelial lesions (HSILs), 50 low-grade squamous intraepithelial lesions (LSILs), and 50 normal cervical tissues. Bisulfite sequencing polymerase chain reaction analysis was used to examine the methylation status of the C8orf4 locus in CSCC and normal cervical tissues. The expression rates of C8orf4 and β-catenin were significantly higher in CSCCs or HSILs than in LSILs or normal cervical tissues (P < .05). C8orf4 expression was positively correlated with the poor differentiation of CSCCs (P = .009), and with aberrant expression of β-catenin in CSCCs (P = .002) and squamous intraepithelial lesions (P < .001). The methylation rate of C8orf4 in CSCCs was significantly lower than that in normal cervical tissues (P = .001). The Cancer Genome Atlas genomics data also confirmed that the mRNA expression of C8orf4 was positively associated with the copy number alteration of C8orf4 (correlation coefficient = 0.213, P < .001), and negatively correlated with the methylation level of C8orf4 (correlation coefficient = -0.408, P < .001). In conclusion, the expressions of C8orf4 and β-catenin were synergistically increased in CSCCs and HSILs and higher than those in LSILs and normal cervical tissues. The methylation level of C8orf4 is decreased in CSCCs and is responsible for the increased expression of C8orf4.

Targeting liver cancer stem cells for the treatment of hepatocellular carcinoma

Liver cancer is one of the most common malignant tumors and prognosis remains poor. It has been increasingly recognized that liver cancer stem cells (LCSCs) are responsible for the carcinogenesis, recurrence, metastasis and chemoresistance of hepatocellular carcinoma (HCC). Targeting LCSCs is promising to be a new direction for the treatment of HCC. Herein, we summarize the potentially therapeutic targets in LCSCs at the level of genes, molecules and cells, such as knockout of oncogenes or oncoproteins, restoring the silent tumor suppressor genes, inhibition of the transcription factors and regulation of noncoding RNAs (including microRNAs and long noncoding RNAs) in LCSCs at the genetic level; inhibition of markers and blockade of the key signaling pathways of LCSCs at the molecular level; and inhibiting autophagy and application of oncolytic adenoviruses in LCSCs at the cellular level. Moreover, we analyze the potential targets in LCSCs to eliminate chemoresistance of HCC. Thereinto, the suppression of autophagy and Nanog by chloroquine and shRNA respectively may be the most promising targeting approaches. These targets may provide novel therapeutic strategies for the treatment of HCC by targeting LCSCs.

Radioguided thyroidectomy for follicular tumors: Multicentric experience

BACKGROUND

The diagnosis of thyroid nodular diseases requires an integrated approach that has been widely established over the past years. This strategy includes: ultrasonography (US) with; implemented Color-Power-Doppler, conventional scintigraphy also with positive indicators, specific pathological studies targeted by immunohistochemically-assays, and the fine needle; aspiration biopsy (FNAB), which, usually, in case of "Follicular Lesions" (10-20%) findings is; unable to distinguish carcinoma from follicular adenoma, then indicating the necessity of surgery to; obtain a correct diagnosis. The aim of this study was to evaluate the role of the scintigraphy with; positive indicators, both preoperatively in diagnostic approach of the thyroid nodules and; intraoperatively as a guide to the extension of the surgical excision.

METHODS

On 4482 Thyroidectomy performed, we selected 360 cases of follicular neoplasms (192; females and 168 males). In the preoperative phase, these patients underwent 99 m Tc-sestaMIBI; scintigraphy with both early (10 min) and late (2 h) image acquisition, which were later; compared to the ones obtained by image subtraction of means 99 m Tc-pertechnetate. Following the; sestamibi administration before intervention, we selected the most up-taking nodularity with the; assistance of a specific surgical probe (Neoprobe), quantifying uptake with relation to the surgical pathology, for an amount of 324 total thyroidectomies and 36 hemi thyroidectomies.

RESULTS

In all cases of multinodular goiter the benign nodules showed an intraoperative low sestamibi uptake whereas follicular carcinomas showed both a high preoperative uptake and, as a; percentage, the highest values of intraoperative uptake; on the other hand, follicular adenomas had; both pre-and intraoperative mean values of uptake. On the contrary, papillary carcinomas only; showed a mild uptake.

CONCLUSIONS

Preoperative sestamibi scintigraphy confirmed its importance in improving the information obtained through different diagnostic investigations. Also intraoperatively, it pointed; out high-risk nodules more accurately. Therefore, radio (Sestamibi) guided surgery could have an; interesting rule in the thyroid follicular lesion treatment.

Of Wnts and Ribosomes

Wnt proteins are secreted glycoproteins that activate different intracellular signal transduction pathways. They regulate cell proliferation and are required for proper embryonic development. Misregulation of Wnt signaling can result in various diseases including cancer. In most circumstances, cell growth is essential for cell division and thus cell proliferation. Therefore, several reports have highlighted the key role of Wnt proteins for cell growth. Ribosomes represent the cellular protein synthesis machinery and cells need to be equipped with an appropriate number of ribosomes to allow cell growth. Recent findings suggest a role for Wnt proteins in regulating ribosome biogenesis and we here summarize these findings representing a previously unknown function of Wnt proteins. Understanding this role of Wnt signaling might open new avenues to slow down proliferation by drugs for instance in cancer therapy.

Thyroid cancer 1 (C8orf4) shows high expression, no mutation and reduced methylation level in lung cancers, and its expression correlates with β-catenin and DNMT1 expression and poor prognosis

Thyroid cancer 1 (TC1, C8orf4) plays important roles in tumors. The aim of this study was to examine the protein expression levels, methylation status, and mutational status of TC1 (C8orf4) in lung cancers, and investigate the correlation between TC1, other members of the Wnt signaling pathway, and lung cancer. TC1 expression levels were assessed via immunohistochemical staining in 179 cases of lung cancer. β-catenin, TCF4, Axin, Disabled-2, Chibby, and DNA methyltransferase-1 (DNMT1) expressions were also examined. Bisulfite sequencing PCR analysis was used to examine the methylation status of the C8orf4 locus, while PCR analysis and direct sequencing were used to determine its mutational status. We found high TC1 expression correlated with poor differentiation, advanced TNM stage, lymphatic metastasis, and poor prognosis in lung cancer patients. TC1 expression also correlated with β-catenin and DNMT1 expressions. No mutations in C8orf4 were detected. However, methylation levels of C8orf4 in lung cancers were lower than in corresponding normal lung tissues. In conclusion, high TC1 expression is implicated in lung cancer progression and correlates with poor prognosis in lung cancer. Reduced methylation levels might be responsible for the elevated TC1 expression levels. TC1, β-catenin, and DNMT1 can synergistically activate Wnt/β-catenin signaling in lung cancers.

Adipose tissue hyperplasia with enhanced adipocyte-derived stem cell activity in Tc1(C8orf4)-deleted mice

Adipose tissue hyperplasia with increased number of adipocytes is implicated in a protective rather than deleterious effect on obesity-associated metabolic disorder. It is poorly understood how the adipose tissue cellularity is regulated. Tc1 is a gene of vertebrates that regulates diverse downstream genes. Young Tc1-deleted mice fed on standard chow diet show expanded adipose tissue with smaller adipocytes in size compared to wild type controls, representing adipose tissue hyperplasia. Tc1^-/- mice show enhanced glucose tolerance and reduced serum lipids. Adipocyte-derived stem cells (ADSCs) from Tc1^-/- mice show enhanced proliferative and adipogenic capacity compared to wild type controls, suggesting that the adipose hyperplasia is regulated at the stem cell level. PPARγ and CEBPα are up-regulated robustly in Tc1^-/- ADSCs upon induction for adipogenesis. Wisp2 and Dlk1, inhibitors of adipogenesis, are down-regulated in Tc1^-/- ADSCs compared to controls. Tc1-transfected NIH3T3 cells show higher β-catenin reporter signals than vector transfected controls, suggesting a role of canonical Wnt signaling in the Tc1-dependent adipose regulation. Our data support that Tc1 is a novel regulator for adipose stem cells. Adipose tissue hyperplasia may be implicated in the metabolic regulation of Tc1^-/- mice.

Conformational characterization of the intrinsically disordered protein Chibby: Interplay between structural elements in target recognition

The protein Chibby (Cby) is an antagonist of the Wnt signaling pathway, where it inhibits the binding between the transcriptional coactivator β-catenin and the Tcf/Lef transcription factors. The 126 residue Cby is partially disordered; its N-terminal half is unstructured while its C-terminal half comprises a coiled-coil domain. Previous structural analyses of Cby using NMR spectroscopy suffered from severe line broadening for residues within the protein's C-terminal half, hindering detailed characterization of the coiled-coil domain. Here, we use hydrogen/deuterium exchange-mass spectrometry (HDX-MS) to examine Cby's C-terminal half. Results reveal that Cby is divided into three structural elements: a disordered N-terminal half, a coiled-coil domain, and a C-terminal unstructured extension consisting of the last ∼ 25 residues (which we term C-terminal extension). A series of truncation constructs were designed to assess the roles of individual structural elements in protein stability and Cby binding to TC-1, a positive regulator of the Wnt signaling pathway. CD and NMR data show that Cby maintains coiled-coil structure upon deletion of either disordered region. NMR and ITC binding experiments between Cby and TC-1 illustrate that the interaction is retained upon deletion of either Cby's N-terminal half or its C-terminal extension. Intriguingly, Cby's C-terminal half alone binds to TC-1 with significantly greater affinity compared to full-length Cby, implying that target binding of the coiled-coil domain is affected by the flanking disordered regions.

Knockdown of TC-1 enhances radiosensitivity of non-small cell lung cancer via the Wnt/β-catenin pathway

Thyroid cancer 1 (TC-1, C8ofr4) is widely expressed in vertebrates and associated with many kinds of tumors. Previous studies indicated that TC-1 functions as a positive regulator in the Wnt/β-catenin signaling pathway in non-small cell lung cancer (NSCLC). However, its exact role and regulation mechanism in radiosensitivity of NSCLC are still unclear. The expression level of TC-1 was measured by qRT-PCR and western blot in NSCLC cell lines. Proliferation and apoptosis of NSCLC cells in response to TC-1 knockdown or/and radiation were determined by MTT assay and flow cytometry, respectively. The activation of the Wnt/β-catenin signaling pathway was further examined by western blot in vitro and in vivo. Compared to TC-1 siRNA or radiotherapy alone, TC-1 silencing combined with radiation inhibited cell proliferation and induced apoptosis in NSCLC cell lines by inactivating of the Wnt/β-catenin signaling pathway. Furthermore, inhibition of the Wnt/β-catenin signaling pathway by XAV939, a Wnt/β-catenin signaling inhibitor, contributed to proliferation inhibition and apoptosis induction in NSCLC A549 cells. Combinative treatment of A549 xenografts with TC-1 siRNA and radiation caused significant tumor regression and inactivation of the Wnt/β-catenin signaling pathway relative to TC-1 siRNA or radiotherapy alone. The results from in vitro and in vivo studies indicated that TC-1 silencing sensitized NSCLC cell lines to radiotherapy through the Wnt/β-catenin signaling pathway.

Summary: TC-1 silencing inhibited cell proliferation and induced apoptosis in non-small cell lung cancer (NSCLC) both in vitro and in vivo through the Wnt/β-catenin signaling pathway, thereby increasing the susceptibility of NSCLC to radiotherapy.

Aberrant Activation of Notch Signaling Inhibits PROX1 Activity to Enhance the Malignant Behavior of Thyroid Cancer Cells

Papillary thyroid cancer (PTC) is one of the most common endocrine malignancies associated with significant morbidity and mortality. Although multiple studies have contributed to a better understanding of the genetic alterations underlying this frequently arising disease, the downstream molecular effectors that impact PTC pathogenesis remain to be further defined. Here, we report that the regulator of cell fate specification, PROX1, becomes inactivated in PTC through mRNA downregulation and cytoplasmic mislocalization. Expression studies in clinical specimens revealed that aberrantly activated NOTCH signaling promoted PROX1 downregulation and that cytoplasmic mislocalization significantly altered PROX1 protein stability. Importantly, restoration of PROX1 activity in thyroid carcinoma cells revealed that PROX1 not only enhanced Wnt/β-catenin signaling but also regulated several genes known to be associated with PTC, including thyroid cancer protein (TC)-1, SERPINA1, and FABP4. Furthermore, PROX1 reexpression suppressed the malignant phenotypes of thyroid carcinoma cells, such as proliferation, motility, adhesion, invasion, anchorage-independent growth, and polyploidy. Moreover, animal xenograft studies demonstrated that restoration of PROX1 severely impeded tumor formation and suppressed the invasiveness and the nuclear/cytoplasmic ratio of PTC cells. Taken together, our findings demonstrate that NOTCH-induced PROX1 inactivation significantly promotes the malignant behavior of thyroid carcinoma and suggest that PROX1 reactivation may represent a potential therapeutic strategy to attenuate disease progression.

The combination of four molecular markers improves thyroid cancer cytologic diagnosis and patient management

Background

Papillary thyroid cancer is the most common endocrine malignancy. The most sensitive and specific diagnostic tool for thyroid nodule diagnosis is fine-needle aspiration (FNA) biopsy with cytological evaluation. Nevertheless, FNA biopsy is not always decisive leading to “indeterminate” or “suspicious” diagnoses in 10 %–30 % of cases. BRAF V600E detection is currently used as molecular test to improve the diagnosis of thyroid nodules, yet it lacks sensitivity. The aim of the present study was to identify novel molecular markers/computational models to improve the discrimination between benign and malignant thyroid lesions.

Methods

We collected 118 pre-operative thyroid FNA samples. All 118 FNA samples were characterized for the presence of the BRAF V600E mutation (exon15) by pyrosequencing and further assessed for mRNA expression of four genes (KIT, TC1, miR-222, miR-146b) by quantitative polymerase chain reaction. Computational models (Bayesian Neural Network Classifier, discriminant analysis) were built, and their ability to discriminate benign and malignant tumors were tested. Receiver operating characteristic (ROC) analysis was performed and principal component analysis was used for visualization purposes.

Results

In total, 36/70 malignant samples carried the V600E mutation, while all 48 benign samples were wild type for BRAF exon15. The Bayesian neural network (BNN) and discriminant analysis, including the mRNA expression of the four genes (KIT, TC1, miR-222, miR-146b) showed a very strong predictive value (94.12 % and 92.16 %, respectively) in discriminating malignant from benign patients. The discriminant analysis showed a correct classification of 100 % of the samples in the malignant group, and 95 % by BNN. KIT and miR-146b showed the highest diagnostic accuracy of the ROC curve, with area under the curve values of 0.973 for KIT and 0.931 for miR-146b.

Conclusions

The four genes model proposed in this study proved to be highly discriminative of the malignant status compared with BRAF assessment alone. Its implementation in clinical practice can help in identifying malignant/benign nodules that would otherwise remain suspicious.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1917-2) contains supplementary material, which is available to authorized users.

Human Thyroid Cancer-1 (TC-1) is a vertebrate specific oncogenic protein that protects against copper and pro-apoptotic genes in yeast

The human Thyroid Cancer-1 (hTC-1) protein, also known as C8orf4 was initially identified as a gene that was up-regulated in human thyroid cancer. Here we show that hTC-1 is a peptide that prevents the effects of over-expressing Bax in yeast. Analysis of the 106 residues of hTC-1 in available protein databases revealed direct orthologues in jawed-vertebrates, including mammals, frogs, fish and sharks. No TC-1 orthologue was detected in lower organisms, including yeast. Here we show that TC-1 is a general pro-survival peptide since it prevents the growth- and cell death-inducing effects of copper in yeast. Human TC-1 also prevented the deleterious effects that occur due to the over-expression of a number of key pro-apoptotic peptides, including YCA1, YBH3, NUC1, and AIF1. Even though the protective effects were more pronounced with the over-expression of YBH3 and YCA1, hTC-1 could still protect yeast mutants lacking YBH3 and YCA1 from the effects of copper sulfate. This suggests that the protective effects of TC-1 are not limited to specific pathways or processes. Taken together, our results indicate that hTC-1 is a pro-survival protein that retains its function when heterologously expressed in yeast. Thus yeast is a useful model to characterize the potential roles in cell death and survival of cancer related genes.

C8orf4 negatively regulates self-renewal of liver cancer stem cells via suppression of NOTCH2 signalling

Liver cancer stem cells (CSCs) harbour self-renewal and differentiation properties, accounting for chemotherapy resistance and recurrence. However, the molecular mechanisms to sustain liver CSCs remain largely unknown. In this study, based on analysis of several hepatocellular carcinoma (HCC) transcriptome datasets and our experimental data, we find that C8orf4 is weakly expressed in HCC tumours and liver CSCs. C8orf4 attenuates the self-renewal capacity of liver CSCs and tumour propagation. We show that NOTCH2 is activated in liver CSCs. C8orf4 is located in the cytoplasm of HCC tumour cells and associates with the NOTCH2 intracellular domain, which impedes the nuclear translocation of N2ICD. C8orf4 deletion causes the nuclear translocation of N2ICD that triggers the NOTCH2 signalling, which sustains the stemness of liver CSCs. Finally, NOTCH2 activation levels are consistent with clinical severity and prognosis of HCC patients. Altogether, C8orf4 negatively regulates the self-renewal of liver CSCs via suppression of NOTCH2 signalling.

Chibby functions in Xenopus ciliary assembly, embryonic development, and the regulation of gene expression

Wnt signaling and ciliogenesis are core features of embryonic development in a range of metazoans. Chibby (Cby), a basal-body associated protein, regulates β-catenin-mediated Wnt signaling in the mouse but not Drosophila. Here we present an analysis of Cby's embryonic expression and morphant phenotypes in Xenopus laevis. Cby RNA is supplied maternally, negatively regulated by Snail2 but not Twist1, preferentially expressed in the neuroectoderm, and regulates β-catenin-mediated gene expression. Reducing Cby levels reduced the density of multiciliated cells, the number of basal bodies per multiciliated cell, and the numbers of neural tube primary cilia; it also led to abnormal development of the neural crest, central nervous system, and pronephros, all defects that were rescued by a Cby-GFP chimera. Reduction of Cby led to an increase in Wnt8a and decreases in Gli2, Gli3, and Shh RNA levels. Many, but not all, morphant phenotypes were significantly reversed by the Wnt inhibitor SFRP2. These observations extend our understanding of Cby's role in mediating the network of interactions between ciliogenesis, signaling systems and tissue patterning.

TC-1 overexpression promotes cell proliferation in human non-small cell lung cancer that can be inhibited by PD173074

Thyroid cancer-1 (TC-1), a natively disordered protein, is widely expressed in vertebrates and overexpressed in many kinds of tumors. However, its exact role and regulation mechanism in human non-small cell lung cancer (NSCLC) are still unclear. In the present study, we found that TC-1 is highly expressed in NSCLC and that its aberrant expression is strongly associated with NSCLC cell proliferation. Exogenous TC-1 overexpression promotes cell proliferation, accelerates the cell G1-to-S-phase transition, and reduces apoptosis in NSCLC. The knockdown of TC-1, however, inhibits NSCLC cell proliferation, cycle transition, and apoptosis resistance. Furthermore, we also demonstrated that PD173074, which functions as an inhibitor of the TC-1 in NSCLC, decreases the expression of TC-1 and inhibits TC-1 overexpression mediated cell proliferation in vitro and in vivo. Nevertheless, the inhibition function of PD173074 on NSCLC cell proliferation was eliminated in cells with TC-1 knockdown. These results suggest that PD173074 plays a significant role in TC-1 overexpression mediated NSCLC cell proliferation and may be a potential intervention target for the prevention of cell proliferation in NSCLC.

TC1(C8orf4) regulates hematopoietic stem/progenitor cells and hematopoiesis

Hematopoiesis is a complex process requiring multiple regulators for hematopoietic stem/progenitor cells (HSPC) and differentiation to multi-lineage blood cells. TC1(C8orf4) is implicated in cancers, hematological malignancies and inflammatory activation. Here, we report that Tc1 regulates hematopoiesis in mice. Myeloid and lymphoid cells are increased markedly in peripheral blood of Tc1–deleted mice compared to wild type controls. Red blood cells are small-sized but increased in number. The bone marrow of Tc1^−/− mice is normocellular histologically. However, Lin⁻Sca-1⁺c-Kit⁺ (LSK) cells are expanded in Tc1^−/− mice compared to wild type controls. The expanded population mostly consists of CD150⁻CD48⁺ cells, suggesting the expansion of lineage-restricted hematopoietic progenitor cells. Colony forming units (CFU) are increased in Tc1^−/− mice bone marrow cells compared to controls. In wild type mice bone marrow, Tc1 is expressed in a limited population of HSPC but not in differentiated cells. Major myeloid transcriptional regulators such as Pu.1 and Cebpα are not up-regulated in Tc1^−/− mice bone marrow. Our findings indicate that TC1 is a novel hematopoietic regulator. The mechanisms of TC1-dependent HSPC regulation and lineage determination are unknown.

TC-1 (c8orf4) enhances aggressive biologic behavior in lung cancer through the Wnt/β-catenin pathway

BACKGROUND

The thyroid cancer-1 (TC-1) or c8orf4 gene encodes a 106-residue naturally disordered protein that has been found to be associated with thyroid, gastric, and breast cancer. A recent study has indicated that the protein functions as a positive regulator in the Wnt/β-catenin signaling pathway in human breast cancer. However, no research has been done in the area of lung cancer. Therefore, the goal of the present study was to confirm the relationship among TC-1, lung cancer, and the Wnt/β-catenin signaling pathway.

MATERIALS AND METHODS

The expression of TC-1 was immunohistochemically examined in 147 patients with non-small-cell lung cancer. TC-1-overexpressed and silenced A549 cells were infected using lentivirus and MTT cell proliferation analysis, and Matrigel invasion assays and scratch-wound assays were performed to confirm the biologic behavioral changes in different A549 cell subsets. The Wnt/β-catenin signaling pathway, key gene β-catenin, target genes of vascular endothelial growth factor, cyclin D1, matrix metalloproteinase-7, c-myc, and survivin were tested at the mRNA and protein level.

RESULTS

TC-1 was detected in 97 of the 147 non-small-cell lung cancer primary tumor specimens, and its expression correlated with the TNM stage and regional lymph node metastasis (P < 0.01). In vitro experiments demonstrated that TC-1 expression affected both proliferation and invasion in the A549 cell line. Furthermore, expression of TC-1 protein affected the Wnt/β-catenin signaling pathway's downstream genes, such as vascular endothelial growth factor and matrix metalloproteinase-7, at the mRNA and protein level.

CONCLUSIONS

TC-1 expression is associated with aggressive biologic behavior in lung cancer and might coordinate with the Wnt/β-catenin pathway as a positive upstream regulator that induces these behaviors.

TC-1 (C8orf4) expression is correlated with differentiation in ovarian carcinomas and might distinguish metastatic ovarian from metastatic colorectal carcinomas

Thyroid cancer 1 (TC-1, C8orf4) is involved in the development of many cancers. In this study, we investigated the correlation between the expression of TC-1 and the clinicopathological characteristics of ovarian and colorectal adenocarcinomas. We also explored the possible use of TC-1 as a marker to distinguish between metastatic tumors of the ovary and colorectum. We used immunohistochemistry to examine the expression level of TC-1 in 100 ovarian and 100 colorectal adenocarcinomas and 25 metastatic carcinomas with the ovary or colorectum as primary site. TC-1 was expressed in all ovarian carcinoma samples. The high expression rate of TC-1 was 84 % in ovarian carcinomas, which was much higher than that observed in colorectal adenocarcinomas (35 %, P < 0.001). High expression of TC-1 significantly correlated with poor differentiation of ovarian carcinomas (P = 0.013). To explore the value of TC-1 in distinguishing metastatic ovarian cancers from colorectal cancers, we found the area under the receiver operator characteristic curve of TC-1 to be 0.819 (95 % confidence interval, 0.760-0.878; P < 0.001). Furthermore, TC-1 was highly expressed in 100 % of nine metastatic ovarian cancers, but only in 31 % of 16 metastatic colorectal cancers. The higher expression of TC-1 in ovarian compared to colorectal adenocarcinomas suggests its potential use as a marker, to distinguish between metastatic ovarian and colorectal adenocarcinomas.

Effects of molecular crowding on the dynamics of intrinsically disordered proteins

Inside cells, the concentration of macromolecules can reach up to 400 g/L. In such crowded environments, proteins are expected to behave differently than in vitro. It has been shown that the stability and the folding rate of a globular protein can be altered by the excluded volume effect produced by a high density of macromolecules. However, macromolecular crowding effects on intrinsically disordered proteins (IDPs) are less explored. These proteins can be extremely dynamic and potentially sample a wide ensemble of conformations under non-denaturing conditions. The dynamic properties of IDPs are intimately related to the timescale of conformational exchange within the ensemble, which govern target recognition and how these proteins function. In this work, we investigated the macromolecular crowding effects on the dynamics of several IDPs by measuring the NMR spin relaxation parameters of three disordered proteins (ProTα, TC1, and α-synuclein) with different extents of residual structures. To aid the interpretation of experimental results, we also performed an MD simulation of ProTα. Based on the MD analysis, a simple model to correlate the observed changes in relaxation rates to the alteration in protein motions under crowding conditions was proposed. Our results show that 1) IDPs remain at least partially disordered despite the presence of high concentration of other macromolecules, 2) the crowded environment has differential effects on the conformational propensity of distinct regions of an IDP, which may lead to selective stabilization of certain target-binding motifs, and 3) the segmental motions of IDPs on the nanosecond timescale are retained under crowded conditions. These findings strongly suggest that IDPs function as dynamic structural ensembles in cellular environments.

A molecular computational model improves the preoperative diagnosis of thyroid nodules

Background

Thyroid nodules with indeterminate cytological features on fine needle aspiration (FNA) cytology have a 20% risk of thyroid cancer. The aim of the current study was to determine the diagnostic utility of an 8-gene assay to distinguish benign from malignant thyroid neoplasm.

Methods

The mRNA expression level of 9 genes (KIT, SYNGR2, C21orf4, Hs.296031, DDI2, CDH1, LSM7, TC1, NATH) was analysed by quantitative PCR (q-PCR) in 93 FNA cytological samples. To evaluate the diagnostic utility of all the genes analysed, we assessed the area under the curve (AUC) for each gene individually and in combination. BRAF exon 15 status was determined by pyrosequencing. An 8-gene computational model (Neural Network Bayesian Classifier) was built and a multiple-variable analysis was then performed to assess the correlation between the markers.

Results

The AUC for each significant marker ranged between 0.625 and 0.900, thus all the significant markers, alone and in combination, can be used to distinguish between malignant and benign FNA samples. The classifier made up of KIT, CDH1, LSM7, C21orf4, DDI2, TC1, Hs.296031 and BRAF had a predictive power of 88.8%. It proved to be useful for risk stratification of the most critical cytological group of the indeterminate lesions for which there is the greatest need of accurate diagnostic markers.

Conclusion

The genetic classification obtained with this model is highly accurate at differentiating malignant from benign thyroid lesions and might be a useful adjunct in the preoperative management of patients with thyroid nodules.

A link between smooth muscle cell death and extracellular matrix degradation during vascular atrophy

OBJECTIVE

High blood flow induces neointimal atrophy in polytetrafluoroethylene (PTFE) aortoiliac grafts and a tight external PTFE wrap of the iliac artery induces medial atrophy. In both nonhuman primate models, atrophy with loss of smooth muscle cells and extracellular matrix (ECM) begins at ≤4 days. We hypothesized that matrix loss would be linked to cell death, but the factors and mechanisms involved are not known. The purpose of this study was to determine commonly regulated genes in these two models, which we hypothesized would be a small set of genes that might be key regulators of vascular atrophy.

METHODS

DNA microarray analysis (Sentrix Human Ref 8; Illumina, San Diego, Calif; ∼23,000 genes) was performed on arterial tissue from the wrap model (n = 9) and graft neointima from the graft model (n = 5) 1 day after wrapping or the switch to high flow, respectively. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was also performed. Expression of this vascular atrophy gene set was also studied after Fas ligand-induced cell death in cultured smooth muscle cells and organ cultured arteries.

RESULTS

Microarray analysis showed 15 genes were regulated in the same direction in both atrophy models: 9 upregulated and 6 downregulated. Seven of nine upregulated genes were confirmed by qRT-PCR in both models. Upregulated genes included the ECM-degrading enzymes ADAMTS4, tissue plasminogen activator (PLAT), and hyaluronidase 2; possible growth regulatory factors, including chromosome 8 open reading frame 4 and leucine-rich repeat family containing 8; a differentiation regulatory factor (musculoskeletal embryonic nuclear protein 1); a dead cell removal factor (ficolin 3); and a prostaglandin transporter (solute carrier organic anion transporter family member 2A1). Five downregulated genes were confirmed but only in one or the other model. Of the seven upregulated genes, ADAMTS4, PLAT, hyaluronidase 2, solute carrier organic anion transporter family member 2A1, leucine-rich repeat family containing 8, and chromosome 8 open reading frame 4 were also upregulated in vitro in cultured smooth muscle cells or cultured iliac artery by treatment with FasL, which causes cell death. However, blockade of caspase activity with Z-VAD inhibited FasL-mediated cell death, but not gene induction.

CONCLUSION

Seven gene products were upregulated in two distinctly different in vivo nonhuman primate vascular atrophy models. Induction of cell death by FasL in vitro induced six of these genes, including the ECM-degrading factors ADAMTS4, hyaluronidase 2, and PLAT, suggesting a mechanism by which the program of tissue atrophy coordinately removes extracellular matrix as cells die. These genes may be key regulators of vascular atrophy.

Structural characterization of partially disordered human Chibby: insights into its function in the Wnt-signaling pathway

The Wnt/β-catenin signaling pathway is critical to embryonic development as well as adult tissue regeneration. Dysregulation of this pathway can lead to a variety of human diseases, in particular cancers. Chibby (Cby), a small and highly conserved protein, plays an antagonistic role in Wnt signaling by inhibiting the binding of β-catenin to Tcf/Lef family proteins, a protein interaction that is essential for the transcriptional activation of Wnt target genes. Cby is also involved in regulating intracellular distribution of β-catenin. Phosphorylated Cby forms a ternary complex with 14-3-3 protein and β-catenin, facilitating the export of β-catenin from the nucleus. On the other hand, the antagonistic function of Cby is inhibited upon binding to thyroid cancer-1 (TC-1). To dissect the structure−function relationship of Cby, we have used NMR spectroscopy, ESI-MS, CD, and DLS to extensively characterize the structure of human Cby. Our results show that the 126-residue Cby is partially disordered under nondenaturing conditions. While the N-terminal portion of the protein is predominantly unstructured in solution, the C-terminal half of Cby adopts a coiled-coil structure through self-association. Initial data for the binding studies of Cby to 14-3-3ζ (one of the isoforms in the 14-3-3 family) and TC-1 via these two distinct structural modules have also been obtained. It is noteworthy that in a recent large-scale analysis of the intrinsically disordered proteome of mouse, a substantial number of disordered proteins are predicted to have coiled-coil motif presence in their sequences. The combination of these two molecular recognition features could facilitate disordered Cby in assembling protein complexes via different modes of interaction.

Investigation of copy-number variations of C8orf4 in hematological malignancies

C8orf4, thyroid cancer-1 (TC1), was first identified in papillary thyroid carcinoma and encodes a nucleus-localized protein. A recent array-based study implicated the presence of copy-number variations (CNVs) of C8orf4 in the genomes of acute myelogenous leukemia. However, the functional impact of such regions needs to be extensively investigated in large amount of clinical samples. The purpose of this study is to confirm the relationship between C8orf4 CNVs and hematological malignancies. In our study, we collected bone marrow samples from 515 hematological malignancies and 102 healthy controls. And the CNVs of C8orf4 were detected by real-time PCR. We found significant association between the copy-number deletions of C8orf4 and the risk of these hematological malignancies including acute lymphoblastic leukemia (ALL), acute myelogenous leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myelogenous leukemia (CML), multiple myeloma (MM), and myelodysplastic syndrome (MDS). We also found that the expression of C8orf4 mRNA was relatively lower in the samples with 1 copy of DNA than those with 2 copies of DNA. The CNVs of C8orf4 were associated with the risk of hematological malignancies.

Correlating global gene regulation to angiogenesis in the developing chick extra-embryonic vascular system

Background

Formation of blood vessels requires the concerted regulation of an unknown number of genes in a spatial-, time- and dosage-dependent manner. Determining genes, which drive vascular maturation is crucial for the identification of new therapeutic targets against pathological angiogenesis.

Methology/Principal Findings

We accessed global gene regulation throughout maturation of the chick chorio-allantoic membrane (CAM), a highly vascularized tissue, using pan genomic microarrays. Seven percent of analyzed genes showed a significant change in expression (>2-fold, FDR<5%) with a peak occurring from E7 to E10, when key morphogenetic and angiogenic genes such as BMP4, SMO, HOXA3, EPAS1 and FGFR2 were upregulated, reflecting the state of an activated endothelium. At later stages, a general decrease in gene expression occurs, including genes encoding mitotic factors or angiogenic mediators such as CYR61, EPAS1, MDK and MYC. We identified putative human orthologs for 77% of significantly regulated genes and determined endothelial cell enrichment for 20% of the orthologs in silico. Vascular expression of several genes including ENC1, FSTL1, JAM2, LDB2, LIMS1, PARVB, PDE3A, PRCP, PTRF and ST6GAL1 was demonstrated by in situ hybridization. Up to 9% of the CAM genes were also overexpressed in human organs with related functions, such as placenta and lung or the thyroid. 21–66% of CAM genes enriched in endothelial cells were deregulated in several human cancer types (P<.0001). Interfering with PARVB (encoding parvin, beta) function profoundly changed human endothelial cell shape, motility and tubulogenesis, suggesting an important role of this gene in the angiogenic process.

Conclusions/Significance

Our study underlines the complexity of gene regulation in a highly vascularized organ during development. We identified a restricted number of novel genes enriched in the endothelium of different species and tissues, which may play crucial roles in normal and pathological angiogenesis.

Chibby forms a homodimer through a heptad repeat of leucine residues in its C-terminal coiled-coil motif

Background

The Wnt/β-catenin signaling pathway plays crucial roles in embryonic development and in maintenance of organs and tissues in adults. Chibby (Cby) is an evolutionarily conserved molecule that physically interacts with the key downstream coactivator β-catenin and represses its transcriptional activation potential. Although Cby harbors a predicted coiled-coil motif in the C-terminal region, its molecular nature and functional importance remain largely unexplored.

Results

Here we report that Cby forms a stable complex with itself. Alanine substitutions of two or more of four critical leucine residues within the C-terminal heptad repeats completely eliminate the Cby-Cby interaction. The Cby oligomer predominantly exists as a homodimer. Furthermore, we found that dimerization-deficient Cby mutants still retain the ability to bind to β-catenin and to repress β-catenin-dependent gene activation. More importantly, Cby homodimerization is required for its efficient interaction with the nuclear import receptor importin-α and subsequent nuclear translocation.

Conclusion

Our comprehensive mutational analysis of the Cby coiled-coil domain reveals that the four heptad leucine residues play an essential role in mediating Cby homodimerization. Although monomeric Cby is sufficient to bind to β-catenin and block β-catenin-mediated transcriptional activation, homodimer formation of Cby is indispensable for its efficient nuclear import.

Fine-tuning of nuclear-catenin by Chibby and 14-3-3

Chibby (Cby) is an evolutionarily conserved antagonist of beta-catenin, a central player of the canonical Wnt signaling pathway, which acts as a transcriptional coactivator. Cby physically interacts with the C-terminal activation domain of beta-catenin and blocks its transcriptional activation potential through competition with DNA-binding Tcf/Lef transcription factors. Our recent study revealed a second mechanism for Cby-mediated beta-catenin inhibition in which Cby cooperates with 14-3-3 adaptor proteins to facilitate nuclear export of beta-catenin, following phosphorylation of Cby by Akt kinase. Therefore, our findings unravel a novel molecular mechanism regulating the dynamic nucleo-cytoplasmic trafficking of beta-catenin and provide new insights into the cross-talk between the Wnt and Akt signaling pathways. Here, we review recent literature concerning Cby function and discuss our current understanding of the relationship between Wnt and Akt signaling.

TC1(C8orf4) correlates with Wnt/beta-catenin target genes and aggressive biological behavior in gastric cancer

PURPOSE

We have recently reported that TC1(C8orf4), a small protein present in vertebrates, functions as a novel regulator of the Wnt/beta-catenin pathway. TC1 up-regulates beta-catenin target genes that are implicated in the aggressive behavior of cancers. Our aim was to investigate the clinical and pathobiological relevance of TC1 in gastric cancer.

EXPERIMENTAL DESIGN

The expression of TC1 was analyzed using tissue microarray in correlation with clinicopathologic variables and beta-catenin target genes in 299 gastric cancers. The biological effects of TC1 on Matrigel invasiveness and the proliferation of cancer cells were analyzed. TC1 expression was analyzed in gastric cancer cells after serial peritoneal implantation in nude mice.

RESULTS

TC1 expression was present in 111 carcinomas (37.1%), correlating with tumor stage (P < 0.002), poor differentiation (P < 0.001), lymphatic infiltration (P < 0.005), and lymph node metastasis (P < 0.006). TC1 also correlated with poor survival in diffuse type carcinomas (P < 0.0001), and even in patients with lymph node metastasis (P < 0.0014). TC1 also correlated with the expression of beta-catenin target genes including laminin gamma2, metalloproteinase-7 and metalloproteinase-14, cyclin D1, c-Met, and CD44. TC1 enhanced Matrigel invasiveness and proliferation, supporting its role in the aggressive biological behavior of cancers. The expression of TC1 increased in MKN45 cells after serial peritoneal seeding in nude mice.

CONCLUSIONS

Our data suggests that TC1 coordinates the up-regulation of Wnt/beta-catenin target genes that are implicated in the aggressive biological behavior of cancers. The strong clinical relevance, even in patients with lymph node metastasis, suggested that TC1 could be a potential therapeutic target of advanced gastric cancers.

Transforming properties of TC-1 in human breast cancer: interaction with FGFR2 and beta-catenin signaling pathways

Breast cancer development is associated with gene amplification and over expression that is believed to have a causative role in oncogenesis. Previous studies have demonstrated that over expression of TC-1(C8orf4) mRNA occurs in approximately 50% of breast cancer cell lines and primary tumor specimens. Here, we show that TC-1 has transforming properties in human mammary epithelial (HME) cells and its expression is mechanistically linked to FGFR signaling cascades. In vitro experiments demonstrate that TC-1 over expression mediates both anchorage-independent and growth factor-independent proliferation of HME cells. TC-1 was down regulated by the FGFR inhibitor PD173074 in the breast cancer cell line SUM-52 that also has an FGFR2 gene amplification and over expression. Furthermore, forced expression of FGFR2 in HME cells increased the level of expression of endogenous TC-1 mRNA. TC-1 has been implicated as a modulator of Wnt/beta-catenin signaling in 293 cells and in gastric cancer cells. However, while we did find increased expression of a subset of beta-catenin target genes in TC-1 over expressing cells, we did not find an association of TC-1 with global expression of beta-catenin target genes in our cells. Taken together, our data suggest that TC-1 over expression is transforming and may link with the FGFR pathway in a subset of breast cancer.

The intrinsically disordered TC-1 interacts with Chibby via regions with high helical propensity

Thyroid cancer 1 (TC-1) is a 106-residue naturally disordered protein that has been found to associate with thyroid, gastric, and breast cancers. Recent studies showed that the protein functions as a positive regulator in the Wnt/beta-catenin signaling pathway, a pathway that is known to play essential roles in developmental processes and causes tumor formation when misregulated. By competing with beta-catenin for binding to Chibby (Cby), a conserved nuclear protein that antagonizes the beta-catenin-mediated transcriptions, TC-1 up-regulates a number of beta-catenin target genes that are known to be involved in the aggressive behavior of cancers. In order to gain a molecular understanding of the role TC-1 plays in regulating the Wnt/beta-catenin signaling pathway, detailed structural studies of the protein and its interaction with Cby are essential. In this work, we used nuclear magnetic resonance (NMR) spectroscopy to elucidate the structure of TC-1 and its interaction with Cby. Our results indicate that even though TC-1 is naturally disordered, the protein adopts fairly compact conformations under nondenaturing conditions. Chemical shift analysis and relaxation measurements show that three regions (D44-R53, K58-A64, and D73-T88) with high-helical propensity are present in the C-terminal portion of TC-1. Upon addition of Cby, significant broadening of resonance signals derived from these helical regions of TC-1 was observed. The result indicates that the intrinsically disordered TC-1 interacts with Cby via its transient helical structure.

TC1 (C8orf4) is upregulated by cellular stress and mediates heat shock response

TC1 (C8orf4) is associated with aggressive behavior and poor survival in cancer. We have recently reported that it is a target gene of NF-kappaB and regulates the Wnt/beta-catenin pathway. Here, we show that TC1 is upregulated by various cellular stresses and mediates heat shock response. Heat shock and other cellular stresses including H2O2, 12-O-tetradecanoylphorbol 13-acetate (TPA), lipopolysaccharide (LPS), and UV enhance TC1 transcription in HeLa, KATO-III, HEK293T, and HK cells. TC1 protein then moves into the nuclei independently of NF-kappaB activation. TC1 upregulates heat shock proteins, and TC1-knockdown inhibits stress-induced downstream regulation significantly. Heat shock factor 1(HSF1) and TC1 upregulate each other, suggesting a potential positive feedback in the heat shock response regulation. Our data suggest that TC1 is a novel heat shock response regulator.

Multiple Interacting Oncogenes on the 8p11-p12 Amplicon in Human Breast Cancer

The 8p11-p12 genomic region is amplified in 15% of breast cancers and harbors several candidate oncogenes. However, functional evidence for a transforming role for these genes is lacking. We identified 21 genes from this region as potential oncogenes based on statistical association between copy number and expression. We further showed that three of these genes (LSM1, BAG4, and C8orf4) induce transformed phenotypes when overexpressed in MCF-10A cells, and overexpression of these genes in combination influences the growth factor independence phenotype and the ability of the cells to grow under anchorage-independent conditions. Thus, LSM1, BAG4, and C8orf4 are breast cancer oncogenes that can work in combination to influence the transformed phenotype in human mammary epithelial cells.

C8orf4/TC-1 (thyroid cancer-1) gene expression in thyroid cancer and goiter

BACKGROUND

The expression of the thyroid cancer-1(TC-1) gene seems to be related with malignant transformation in the thyroid tissue.

OBJECTIVE

We evaluated the potential use of TC-1 gene expression as a marker of malignancy in thyroid nodules.

METHODS

A total of 92 frozen thyroid samples were studied, including 46 samples from thyroid nodules (19 papillary carcinomas, 1 follicular carcinoma, 24 adenomatous goiters, and 2 follicular adenomas) and 46 samples from normal surrounding thyroid tissue. Total RNA was extracted and TC-1 expression was assessed by semiquantitative Multiplex PCR. Results were verified using real-time RT-PCR in some of the samples.

RESULTS

Overall mean TC-1 gene expression (normalized by the ABL gene) was 1.73 +/- 1.67 (0.33-9.33). There was a significant difference (p < 0.001) between TC-1 gene expression in benign thyroid lesions (1.07 +/- 0.10) and carcinomas (2.73 +/- 0.51).

CONCLUSION

Our results suggest that TC-1 gene expression may be useful in the differential diagnosis of goiters and thyroid papillary carcinomas.

TC1(C8orf4) is upregulated by IL-1beta/TNF-alpha and enhances proliferation of human follicular dendritic cells

Follicular dendritic cells (FDC) play crucial roles in immune regulation. TNF-alpha has been shown to be essential to the FDC network. However, the molecular regulation of FDC proliferation has not been characterized. Here, we show that TC1(C8orf4), a novel positive regulator of the Wnt/beta-catenin pathway in vertebrates, is upregulated by IL-1beta and TNF-alpha in the human FDC-like line HK. TC1 enhances HK cell proliferation, while TC1-knockdown inhibits the proliferation induced by IL-1beta, suggesting a role of TC1 as a regulator of FDC proliferation. The regulation by pro-inflammatory cytokines suggests that TC1 might be implicated in linking local inflammation to immune response by stimulating FDC.

TC1 (C8orf4) enhances the Wnt/beta-catenin pathway by relieving antagonistic activity of Chibby

The Wnt/beta-catenin pathway has been implicated in human cancers. Here, we show that TC1 (C8orf4), a small protein present in vertebrates, functions as a positive regulator of the pathway. TC1 interacts with Chibby (Cby) and thereby enhances the signaling pathway by relieving the antagonistic function of Cby on the beta-catenin-mediated transcription. Upon coexpression in mammalian cells, TC1 redistributes from nucleolus to nuclear speckles, where it colocalizes with Cby. TC1 up-regulates the expression of beta-catenin target genes that are implicated in invasiveness and aggressive behavior of cancers, such as metalloproteinases, laminin gamma2, and others. Our data indicate that TC1 is a novel upstream regulator of the Wnt/beta-catenin pathway that enhances aggressive behavior of cancers.

Advances in understanding angiogenesis through molecular studies

Tumors, in most cases, need angiogenesis for their sustained growth. A great deal of evidence has suggested that the process of angiogenesis is regulated by the balance between proangiogenic and antiangiogenic factors. Thus, the inhibition of tumor angiogenesis has been considered to be one of the key targets in anticancer therapy, and more than 60 antiangiogenic compounds are currently under clinical evaluation in cancer patients. However, the molecular mechanisms responsible for the activity of many of these antiangiogenic compounds are still not well understood. The recent development of microarray technology has allowed us to investigate the mechanism of action of these inhibitors more rapidly and extensively. With the use of microarray technology, novel molecules and pathways are shown to play a role in angiogenesis. This article also reviews new experimental approaches combined with microarray analysis to identify the molecular pathways involved in tumor-host interactions. Elucidation of the pathways that mediate both angiogenic and antiangiogenic responses will help us to develop better anticancer therapies.

A partial-complementary adapter for an improved and simplified ligation-mediated suppression PCR technique

Ligation-mediated suppression PCR (LMS-PCR) is a powerful tool for walking in unknown genomic DNA regions from known adjacent sequences. This approach has made it feasible to obtain promoter sequences and to enable researchers to identify full-length gene sequences or isoforms of multigene families. However, the advantages of LMS-PCR can be obviated by the presence of incomplete base modifications on the suppression adapters. We propose here that a 'partial-complementary adapter' is a more reliable suppression adapter, demanding only 5'-end phosphorylation. We also describe a simplified procedure for the easier preparation of PCR templates with very small quantities of DNA and a fast and direct characterization of the suppression-PCR products. A set of practical guidelines is proposed for pre-checking the efficiency of the adapter modification using two model systems: bacteriophage lambda (lambda) and Arabidopsis.

Gene profiling reveals specific oncogenic mechanisms and signaling pathways in oncocytic and papillary thyroid carcinoma

The oncogenic pathways in mitochondrial-rich thyroid carcinomas are not clearly understood. To investigate the possible implication of mitochondrial abundance in the genesis of thyroid tumors, we have explored the gene expression profile of six oncocytic carcinomas and six mitochondrial-rich papillary carcinomas using cDNA-microarray technology. A supervised approach allowed us to identify 83 genes differentially expressed in the two types of carcinoma. These genes were classified according to their ontologic profiles. Three genes, NOS3, alpha-actinin-2 and alpha-catenin, suspected of playing a role in tumor genesis, were explored by quantitative RT-PCR analysis and immunohistochemistry. Of the 59 genes overexpressed in papillary carcinomas, 51% were involved in cell communication. Of the 24 genes overexpressed in oncocytic carcinomas, 84% were involved in mitochondrial and cellular metabolism. Our results suggest that mitochondrial respiratory chain complexes III and IV play a significant role in the regulation of reactive oxygen species production by oncocytic tumors.

Early genetic mechanisms underlying the inhibitory effects of endostatin and fumagillin on human endothelial cells

A tumor needs to initiate angiogenesis in order to develop its own blood supply, to grow, to invade, and to spread. Angiogenesis, under normal conditions, is a tightly regulated balance between endogenous pro- and antiangiogenic factors. In this study, we investigated, by microarray analysis, the effects of two known antiangiogenic agents (endostatin and fumagillin) on the gene expression profiles of human umbilical vein endothelial cells (HUVEC) in order to elucidate pathways common to the effects of these agents. We observed a majority of gene expression changes within 1 and 2 h of treatment. The genes demonstrating these early expression changes are involved in cell proliferation, gene transcription, and a number have unknown functions. We selected four genes (DOC1, KLF4, TC-1, ID1) from the microarray profile that showed a similar pattern of expression for both of the antiangiogenic agents we tested. We then used small interfering RNAs (siRNA) in an attempt to better understand the role of these selected genes in the inhibitory activity of these agents. Because the gene expression changes occurred within 1 and 2 h of treatment, these genes might be involved in the initial pathways of angiogenesis inhibition.

C8orf4 is a transforming growth factor B induced transcript downregulated in metastatic colon cancer

Transforming growth factor (TGF) beta mediates a tumor suppressor pathway in human colon epithelial cells. We were interested in identifying and characterizing novel genes regulated by the TGF beta pathway in the colon. We employed expression microarrays to identify transcripts induced by TGF beta in Vaco 330, a colon adenoma cell line. We then used expression microarrays to determine which of these TGF beta induced transcripts are down-regulated in metastatic colon cancer. Northern analysis and real-time reverse transcription PCR confirmed and quantified our findings from the microarrays. These analyses highlighted C8orf4 as induced by TGF beta in colon cells. Moreover, C8orf4 is expressed in most normal colon mucosa samples, and is not expressed in most colon cancer metastases or colon cancer cell lines. Colon cancer primary tumors showed reduced expression of C8orf4 relative to normal mucosa, possibly reflecting contributions of C8orf4 expression in stromal cells. C8orf4 is a gene regulated by TGF beta signaling and loss in advanced colon cancer suggests C8orf4 may play a role in colon cell differentiation or growth regulation.

TC-1 is a novel tumorigenic and natively disordered protein associated with thyroid cancer

A novel gene, thyroid cancer 1 (TC-1), was found recently to be overexpressed in thyroid cancer. TC-1 shows no homology to any of the known thyroid cancer-associated genes. We have produced stable transformants of normal thyroid cells that express the TC-1 gene, and these cells show increased proliferation rates and anchorage-independent growth in soft agar. Apoptosis rates also are decreased in the transformed cells. We also have expressed recombinant TC-1 protein and have undertaken a structural and functional characterization of the protein. The protein is monomeric and predominantly unstructured under conditions of physiologic salt and pH. This places it in the category of natively disordered proteins, a rapidly expanding group of proteins, many members of which play critical roles in cell regulation processes. We show that the protein can be phosphorylated by cyclic AMP-dependent protein kinase and protein kinase C, and the activity of both of these kinases is up-regulated when cells are stably transfected with TC-1. These results suggest that overexpression of TC-1 may be important in thyroid carcinogenesis.

Genomic and Expression Analysis of the 8p11–12 Amplicon in Human Breast Cancer Cell Lines

Gene amplification is an important mechanism of oncogene activation in breast and other cancers. Characterization of amplified regions of the genome in breast cancer has led to the identification of important oncogenes including erbB-2/HER-2, C-MYC, and fibroblast growth factor receptor (FGFR) 2. Chromosome 8p11-p12 is amplified in 10-15% of human breast cancers. The putative oncogene FGFR1 localizes to this region; however, we show evidence that FGFR inhibition fails to slow growth of three breast cancer cell lines with 8p11-p12 amplification. We present a detailed analysis of this amplicon in three human breast cancer cell lines using comparative genomic hybridization, traditional Southern and Northern analysis, and chromosome 8 cDNA microarray expression profiling. This study has identified new candidate oncogenes within the 8p11-p12 region, supporting the hypothesis that genes other than FGFR1 may contribute to oncogenesis in breast cancers with proximal 8p amplification.

A novel vasopressin-induced transcript promotes MAP kinase activation and ENaC downregulation

In the principal cell of the renal collecting duct, vasopressin regulates the expression of a gene network responsible for sodium and water reabsorption through the regulation of the water channel and the epithelial sodium channel (ENaC). We have recently identified a novel vasopressin-induced transcript (VIT32) that encodes for a 142 amino acid vasopressin-induced protein (VIP32), which has no homology with any protein of known function. The Xenopus oocyte expression system revealed two functions: (i) when injected alone, VIT32 cRNA rapidly induces oocyte meiotic maturation through the activation of the maturation promoting factor, the amphibian homolog of the universal M phase trigger Cdc2/cyclin; and (ii) when co-injected with the ENaC, VIT32 cRNA selectively downregulates channel activity, but not channel cell surface expression. In the kidney principal cell, VIP32 may be involved in the downregulation of transepithelial sodium transport observed within a few hours after vasopressin treatment. VIP32 belongs to a novel gene family ubiquitously expressed in oocyte and somatic cells that may be involved in G to M transition and cell cycling.

A Reg family protein is overexpressed in islets from a patient with new-onset type 1 diabetes and acts as T-cell autoantigen in NOD mice

Genes overexpressed in pancreatic islets of patients with new-onset type 1 diabetes are potential candidates for novel disease-related autoantigens. RT-PCR-based subtractive hybridization was used on islets from a patient who died at the onset of type 1 diabetes, and it identified a type 1 diabetes-related cDNA encoding hepatocarcinoma-intestine-pancreas/pancreatic-associated protein (HIP/PAP). This protein belongs to the family of Reg proteins implicated in islet regeneration; its gene contains a putative interleukin-6 (IL-6) response element. Islets from healthy cadaveric human donors released HIP/PAP protein into the culture medium, and this release was enhanced by the addition of IL-6. The expression pattern of mouse homologues of HIP/PAP was determined in pancreata of prediabetic and diabetic NOD mice. Both groups showed positive immunostaining for HIP/PAP in islets and ductal epithelium. To test whether HIP/PAP is a target of islet-directed autoimmunity, we measured splenic T-cell responses against HIP/PAP in NOD mice. Spontaneous proliferation was detected after 4 weeks. Lymphocytes from islet infiltrates and pancreatic lymph nodes from 7- to 10-week-old NOD mice were used to establish an HIP/PAP-specific I-A(g7)-restricted T-cell line, termed WY1, that also responded to mouse islets. WY1 cells homed to islets of NOD-SCID mice and adoptively transferred disease when coinjected with purified CD8(+) cells from diabetic NOD mice. Our conclusion was that differential cloning of Reg from islets of a type 1 diabetic patient and the response of Reg to the cytokine IL-6 suggests that HIP/PAP becomes overexpressed in human diabetic islets because of the local inflammatory response. HIP/PAP acts as a T-cell autoantigen in NOD mice. Therefore, autoimmunity to HIP/PAP might create a vicious cycle, accelerating the immune process leading to diabetes.