Cripto-1 overexpression is involved in the tumorigenesis of nasopharyngeal carcinoma

The role of Nodal and Cripto-1 in human oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a common epithelial malignancy of the oral cavity. Nodal and Cripto-1 (CR-1) are important developmental morphogens expressed in several adult cancers and are associated with disease progression. Whether Nodal and CR-1 are simultaneously expressed in the same tumor and how this affects cancer biology are unclear. We investigate the expression and potential role of both Nodal and CR-1 in human OSCC. Immunohistochemistry results show that Nodal and CR-1 are both expressed in the same human OSCC sample and that intensity of Nodal staining is correlated with advanced-stage disease. However, this was not observed with CR-1 staining. Western blot analysis of lysates from two human OSCC line experiments shows expression of CR-1 and Nodal, and their respective signaling molecules, Src and ERK1/2. Treatment of SCC25 and SCC15 cells with both Nodal and CR-1 inhibitors simultaneously resulted in reduced cell viability and reduced levels of P-Src and P-ERK1/2. Further investigation showed that the combination treatment with both Nodal and CR-1 inhibitors was capable of reducing invasiveness of SCC25 cells. Our results show a possible role for Nodal/CR-1 function during progression of human OSCC and that targeting both proteins simultaneously may have therapeutic potential.

Teratocarcinoma-derived growth factor-1 (Cripto-1) is overexpressed in epithelial odontogenic lesions displaying more aggressive behaviour

PURPOSE

Cripto-1 also known as teratoma-derived growth factor 1 (TDGF-1) belongs to the EGF-CFC family of growth factor-like molecules. Cripto-1 is involved with embryonic development and not expressed in adult tissue, but some tumours are accompanied by reactivation.

METHODS

The aim of this study was to evaluate the immunohistochemical expression of Cripto-1 in most common odontogenic cysts and tumours. Thirty ameloblastomas, 30 keratocysts, 30 dentigerous cysts and two ameloblastic carcinomas were evaluated using the polymeric immunoperoxidase technique. Immunohistochemical expressions were analysed by the IRS (immunoreactive score). Statistical analyses were performed by the Kruskal-Wallis and Mann-Whitney tests (p ≤ 0.05).

RESULTS

Age ranged from 9 to 75 years old, with a prevalence of females (n = 49/53.3%). The mandible was the most affected anatomical site (n = 69/75.0%). Cripto-1 immunoexpression was observed in all ameloblastoma, keratocyst and ameloblastic carcinoma cases, although nine dentigerous cyst cases (30%) were negative. Expression scores were higher in ameloblastoma, keratocyst and ameloblastic carcinoma cases (median ranging from 8 to 11) when compared with dentigerous cyst cases (median of 2), with a statistically significant difference (p < 0.001).

CONCLUSIONS

Cripto-1 is critically important in the progression of several tumours since it is related to significant cell survival and differentiation pathways. The high expression of Cripto-1 in more aggressive odontogenic lesions suggests that this molecule may be involved in the activation of important pathways related to the etiopathogenesis of these lesions.

The Function and Prognostic Significance of Cripto-1 in Colorectal Cancer

Cripto-1 is a plasma membrane protein which is not expressed in adult tissue, but some tumors are accompanied by re-activation. We studied the clinical and biological significance of Cripto-1 in colorectal cancer. Cripto-1 was positive in 68 out of 192 cases (35%) by immunohistochemistry. Cripto-1 expression was correlated with worse prognosis and was an independent prognostic factor. Cripto-1-silenced colorectal cancer cell lines had reduced cell proliferation, migration, and activation of Akt and MAPK signaling pathways in vitro, and decreased tumor growth and lymph node metastasis in vivo. Cripto-1 could be a useful prognostic biomarker and therapeutic target in colorectal cancer.

Epstein-Barr Virus EA-IgA, VCA-IgA, and EBVNA-IgG Antibodies in a Population of Wuhan, China

The study investigated the distribution of Epstein-Barr virus (EBV) EA-IgA, VCA-IgA, and EBVNA-IgG antibodies in a local population of Wuhan, China. Chemiluminescence immunoassay (CLIA) was used to detect EBV EA-IgA, VCA-IgA, and EBVNA-IgG antibodies in 972 subjects undergoing physical examination in Wuhan, and the results were analyzed. The detection rate of EBV was positively correlated with age. In the 972 cases, there was significant difference between different genders in the positive rate of VCA-IgA and EBVNA-IgG. Moreover, the positive rate of VCA-IgA and EBVNA-IgG was higher in men ≥ 60 years old than in those < 60 but no significant differences were found in three antibodies among various age groups. Our results suggested that the EBV infection should be intensively monitored in elderly people in Wuhan.

Cripto-1 expression in patients with clear cell renal cell carcinoma is associated with poor disease outcome

Background

Cripto-1 (CR-1) has been reported to be involved in the development of several human cancers. The potential role of CR-1 in clear cell renal cell carcinoma (ccRCC) is still not clear.

Methods

CR-1 expression was evaluated in ccRCC tissues by Real-time quantitative PCR, Western blot and immunohistochemistry. Serum levels of CR-1 were tested by enzyme-linked immunosorbent assay (ELISA). The clinical significance of CR-1 was analyzed. The effects of CR-1 on cell proliferation, migration, invasion and angiogenesis were investigated in ccRCC cell lines in vitro and in vivo, and markers of the epithelial -mesenchymal transition (EMT) were analyzed. The impact of CR-1 on Wnt/β-catenin signaling pathway was also evaluated in vitro and in vivo.

Results

CR-1 expression was elevated in ccRCC tumor tissues and serum samples. CR-1 expression was correlated with aggressive tumor phenotype and poor survival. Ectopic expression of CR-1 significantly promoted cell proliferation, migration, invasion and angiogenesis whereas knockdown of CR-1 inhibited these activities both in vitro and in vivo. Moreover, we found that CR-1 induced EMT and activated Wnt/β-catenin signaling pathway both in vitro and in vivo.

Conclusions

These results suggest that CR-1 is likely to play important roles in ccRCC development and progression, and that CR-1 is a prognostic biomarker and a promising therapeutic target for ccRCC.

Targeting Nodal and Cripto-1: Perspectives Inside Dual Potential Theranostic Cancer Biomarkers

BACKGROUND

Elucidating the mechanisms of recurrence of embryonic signaling pathways in tumorigenesis has led to the discovery of onco-fetal players which have physiological roles during normal development but result aberrantly re-activated in tumors. In this context, Nodal and Cripto-1 are recognized as onco-developmental factors, which are absent in normal tissues but are overexpressed in several solid tumors where they can serve as theranostic agents.

OBJECTIVE

To collect, review and discuss the most relevant papers related to the involvement of Nodal and Cripto-1 in the development, progression, recurrence and metastasis of several tumors where they are over-expressed, with a particular attention to their occurrence on the surface of the corresponding sub-populations of cancer stem cells (CSC).

RESULTS

We have gathered, rationalized and discussed the most interesting findings extracted from some 370 papers related to the involvement of Cripto-1 and Nodal in all tumor types where they have been detected. Data demonstrate the clear connection between Nodal and Cripto-1 presence and their multiple oncogenic activities across different tumors. We have also reviewed and highlighted the potential of targeting Nodal, Cripto-1 and the complexes that they form on the surface of tumor cells, especially of CSC, as an innovative approach to detect and suppress tumors with molecules that block one or more mechanisms that they regulate.

CONCLUSION

Overall, Nodal and Cripto-1 represent two innovative and effective biomarkers for developing potential theranostic anti-tumor agents that target normal as well as CSC subpopulations and overcome both pharmacological resistance and tumor relapse.

In vivo and in vitro study of co-expression of LMP1 and Cripto-1 in nasopharyngeal carcinoma

INTRODUCTION

Nasopharyngeal carcinoma, an epithelial-derived malignant tumor which because of its anatomical location and atypical early symptoms, when diagnosed invasion and metastasis often have occurred. This requires a better understanding of the development mechanism, identifying diagnostic markers, and developing new treatment strategies.

OBJECTIVE

To study the relationship of LMP1 and Cripto-1 in nasopharyngeal carcinoma.

METHODS

The expression of LMP1 and Cripto-1 in specimens obtained from nasopharyngeal carcinoma patients (n=42) and nasopharyngitis patients (n=22) were examined. The expression of LMP1 and Cripto-1 in LMP1-negative and LMP1-positive (CNE1-LMP1) cells were also examined.

RESULTS

The expression of LMP1 and Cripto-1 was significantly higher in nasopharyngeal carcinoma than in nasopharyngitis (p<0.05). Their expression in nasopharyngeal carcinoma with metastasis were significantly higher than that without metastasis (p<0.05), which was correlated with TNM staging (p<0.05). High Cripto-1 expression and high proliferation rate were seen in CNE1-LMP1 cells.

CONCLUSIONS

The expression of LMP1 and Cripto-1 in nasopharyngeal carcinoma is positively related. Their co-expression might contribute to the proliferation and metastasis of nasopharyngeal carcinoma.

Cripto-1 contributes to stemness in hepatocellular carcinoma by stabilizing Dishevelled-3 and activating Wnt/β-catenin pathway

Identification and characterization of functional molecular targets conferring stemness properties in hepatocellular carcinoma (HCC) offers crucial insights to overcome the major hurdles of tumor recurrence, metastasis and chemoresistance in clinical management. In the current study, we investigated the significance of Cripto-1 in contributing to HCC stemness. Cripto-1 was upregulated in the sorafenib-resistant clones derived from HCC cell lines and patient-derived xenograft that we previously developed, suggesting an association between Cripto-1 and stemness. By in vitro experiments, Cripto-1 fostered cell proliferation, migration, and invasion. It also enhanced self-renewal ability and conferred chemoresistance of HCC cells. Consistently, silencing of Cripto-1 suppressed in vivo tumorigenicity on serial transplantation. On the downstream signaling mechanism, expression of major components of Wnt/β-catenin pathway β-catenin, AXIN2, and C-MYC, accompanied by β-catenin activity was reduced upon Cripto-1 knockdown. The suppressive effects on stemness properties with Cripto-1 knockdown in vitro and in vivo were partially rescued by forced expression of constitutively active β-catenin. Further elucidation revealed the binding of Cripto-1 to Frizzled-7 (FZD7), low-density lipoprotein receptor-related protein 6 (LRP6) and Dishevelled-3 (DVL3) of the Wnt/β-catenin pathway and stabilized DVL3 protein. Analyses with clinical samples validated Cripto-1 overexpression in HCC tissues, as well as a positive correlation between Cripto-1 and AXIN2 expressions. High Cripto-1 level in tumor was associated with poorer disease-free survival of HCC patients. Taken together, Cripto-1 binds to FZD7/LRP6 and DVL3, stabilizes DVL3 expression and activates the Wnt/β-catenin signaling cascade to confer stemness in HCC. Our study findings substantiated the role of Cripto-1 in determining stemness phenotypes of HCC and mechanistically in modulating the Wnt/β-catenin signaling cascade, one of the most frequently deregulated pathways in liver cancer.

High cripto-1 and low miR-205 expression levels as prognostic markers in early stage non-small cell lung cancer

OBJECTIVES

Cripto-1 (CR-1) plays a critical role in the activation of SMAD, SRC, and epithelial-to-mesenchymal transition (EMT) pathways and has been shown to be prognostic in several cancer types. In addition, we showed that CR-1 renders EGFR-mutated NSCLC cells resistant to EGFR-TKI through the activation of SRC and EMT via miR-205 downregulation. This study aimed to investigate the correlation between expression of CR-1 and miR-205 and prognosis of NSCLC patients with or without EGFR mutations.

MATERIALS AND METHODS

A total of 265 patients with stage I (AJCC 6th edition) radically resected NSCLC were tested for CR-1 expression and EGFR mutations by immunohistochemistry and miR-205 expression via qPCR assay.

RESULTS

CR-1 expression was evaluated with immunohistochemistry using a tissue microarray on 265 T1-2N0 surgical NSCLC samples. Of the 265 tumors, 250 (94%) expressed various levels of CR-1. A significant inverse correlation was identified between expression of miR-205 and CR-1. NSCLC patients (T1N0, n = 106) with high CR-1 expression had worse prognosis (shorter recurrence-free survival, p = .045) than those with low CR-1 expression. A similar trend was observed in NSCLC patients with normal preoperative carcinoembryonic antigen (CEA) levels (serum CEA levels <5 ng/ml; n = 179; p = .085); however, no significant correlation was found between CR-1 expression and survival rate in the T2N0 or high CEA groups. In addition, NSCLC patients with low miR-205 expression (n = 126) had poorer prognosis in terms of recurrence than those with high miR-205 expression (n = 127; p = .001).

CONCLUSION

High CR-1 expression is correlated with poor prognosis in NSCLC with low tumor burden and may be used to select high-risk patients for adjuvant chemotherapy in early NSCLC. Moreover, low miR-205 expression likely related to high CR-1 expression could be a prognostic marker for patients with NSCLC.

Biological and Clinicopathological Significance of Cripto-1 Expression in the Progression of Human ESCC

BACKGROUND

Human Cripto-1, a member of the EGF-CFC family, is involved in embryonic development, embryonic stem cell maintenance, and tumor progression. It also participates in multiple cell signaling pathways including Wnt, Notch, and TGF-β. Remarkably, it is expressed in cancer stem cell (CSC) compartments, boosting tumor cell migration, invasion, and angiogenesis. Although Cripto-1 is overexpressed in a variety of human malignant tumors, its expression in esophageal squamous cell carcinoma (ESCC) remains unclear. Our aim in this study was to evaluate the possible oncogenic role of Cripto-1 in ESCC progression and elucidate its association with clinicopathological parameters in patients.

METHODS

In this study, Cripto-1 expression in 50 ESCC tissue samples was analyzed and compared to corresponding margin-normal esophageal tissues using quantitative real-time PCR.

RESULTS

Cripto-1 was overexpressed in nearly 40% of ESCC samples compared with normal tissue samples. Significant correlations were observed between Cripto-1 expression and tumor differentiation grade, progression stage, and location (p < 0.05).

CONCLUSIONS

Our results indicate that overexpression of Cripto-1 is involved in the development of ESCC. Further assessment will be necessary to determine the role of Cripto-1 cross talk in ESCC tumorigenesis.

Cripto-1 promotes epithelial-mesenchymal transition in prostate cancer via Wnt/β-catenin signaling

The Cripto-1 (CR-1) derived EGF-CFC family was overexpressed in tumor development enhancing proliferation, epithelial-mesenchymal transition (EMT) and migration of tumor cells. However, correlation between CR-1 and prostate cancer (PCa) remains still unclear. In the present study, we proved that CR-1 was expressed in PCa and its function was in the progression of PCa. Compared with benign prostatic hyperplasia (BPH) tissues, we confirmed that PCa tissues had high expression of CR-1 by immunohistochemistry and statistical data showed that CR-1 promoted properties of EMT in PCa tissues, including the downregulation of the cell adhesion molecules β-catenin (membrane) and E-cadherin while upregulating transcription factors β-catenin. Overexpression of CR-1 had close relationship with PSA, Gleason, clinical staging and lymph node metastasis in PCa patients. Then, we found that PC-3 cells transfected with CR-1-shRNA inhibited EMT using RT-PCR, RT-qPCR, western blotting and immunofluorescence. Also, we evaluated cell invasive ability in vitro by transwell and wound-healing assay. Our data showed that transfected CR-1-shRNA altered EMT including β-catenin, E-cadherin, c-myc, GSK-3, p-GSK and Wnt/β-catenin pathway in PC-3. It also suppressed PC-3 cell migration. Additionally, our results displayed that Licl had antitumor activity against PC-3 through the inhibition of Wnt/β-catenin pathway. Inhibition of cell viability was dose-time dependent. The present study proved that CR-1 regulates EMT of PCa by Wnt/β-catenin pathway. Hence, CR-1 may provide a new biological marker, and possibly contributes to clinical treatment against PCa.

HIST1H3D: A promising therapeutic target for lung cancer

HIST1H3D gene encodes histone H3.1 and is involved in gene-silencing and heterochromatin formation. HIST1H3D expression is upregulated in primary gastric cancer tissue. In this study, we explored the effects of HIST1H3D expression on lung cancer, and its mechanisms. HIST1H3D expression was measured by immunohistochemistry and RT-PCR in lung cancer tissues and human lung cancer cell lines. Cell proliferation was assessed by MTT assay. Flow cytometric analysis was used to determine cell cycle distribution and apoptosis. Levels of related proteins were detected by western blotting. Bioinformatics analysis was performed to investigate related signaling pathways. cDNA microarray analysis was performed to identify differentially expressed genes following HIST1H3D knockdown. HIST1H3D expression was upregulated in lung cancer tissue samples and the H1299 human lung cancer cell line (P<0.01). Regulation of HIST1H3D expression in nucleus of cells in lung cancer tissues was significant associated with tumor stage (P=0.02) and lymph node metastases (P=0.04). Downregulation of HIST1H3D expression led to suppression of proliferation and colony forming ability, cell cycle arrest at the G0/G1 phase, and promotion of cell apoptosis. The microarray data revealed 522 genes that were differentially expressed after HIST1H3D knockdown in H1299 cells. These genes were shown to be linked to numerous pathways, including the cell cycle, p53 signaling, and MCM. Western blot analysis confirmed upregulated expression of the THBS1 and TP53I3 genes, and downregulated expression of the CDK6, CDKN1 and CCNE2 genes. In conclusion, our results suggest that HIST1H3D is highly expressed in lung cancer cell lines and tissues. Furthermore, HIST1H3D may be important in cell proliferation, apoptosis and cell cycle progression, and is implicated as a potential therapeutic target for lung cancer.

Cripto-1 modulates macrophage cytokine secretion and phagocytic activity via NF-κB signaling

Cripto-1 is an oncogenic protein belonging to the epidermal growth factor–Cripto-1/FRL-1/Cryptic family. It has important roles in tumor formation and metastasis, but its effects on the immune system are unclear. In the present study, we investigated the effects of Cripto-1 overexpression on macrophage activities and examined the underlying mechanisms. A cell line stably overexpressing Cripto-1 was developed. The culture supernatant from this cell line was collected and used to condition macrophages (RAW264.7, THP-1, and primary mouse macrophages) for various times. Exposure to this supernatant significantly increased the mRNA and protein expression levels of the anti-inflammatory cytokine interleukin (IL)-10 and of three pro-inflammatory cytokines (tumor necrosis factor-α, IL-6, and IL-1β), but did not affect the expression of transforming growth factor-β, another anti-inflammatory cytokine. Exposure to this supernatant also enhanced macrophage phagocytosis of chicken erythrocytes and yeast cells. Similar effects were observed in macrophages stimulated with purified Cripto-1 protein. Mechanistic experiments revealed that Cripto-1 activated nuclear factor (NF)-κB signaling by inducing IκB kinase phosphorylation and p65 nuclear translocation. Pretreatment with ammonium pyrrolidine dithiocarbamate, a specific NF-κB inhibitor, inhibited Cripto-1-induced cytokine secretion and phagocytosis of macrophages. Taken together, our present findings suggest that Cripto-1 enhances macrophage phagocytic activity and upregulates the production of anti- and pro-inflammatory cytokines via the NF-κB signaling pathway.

MicroRNA-15b suppresses the growth and invasion of glioma cells through targeted inhibition of cripto-1 expression

Gliomas are the most common type of malignant brain tumor. Studies have identified that miR‑15b is negatively correlated with cripto-1 expression in glioma cells, and these molecules serve an important role in cancer development and progression. The current study was undertaken to further examine the association between these two molecules. Fluorescent quantitative PCR confirmed that miR‑15b expression was significantly downregulated in glioma tissue while cripto‑1 expression was significantly increased. Subsequent to transfection with miR‑15b mimics, cripto‑1 expression was significantly suppressed, and dual luciferase reporter assays further demonstrated that miR‑15b regulates cripto‑1 in a targeted manner. Furthermore, miR‑15b inhibited proliferation and invasion, and promoted apoptosis of glioma cells while downregulating the expression of MMP‑2 and MMP‑9. In contrast, cripto‑1 expression had the opposite effects. Co‑transfection with miR‑15b mimics and the cripto‑1 overexpression vector overcame the inhibitory action of miR‑15b on cripto‑1. Therefore, it is suggested that miR‑15b modulates cell growth and invasion through targeted regulation of cripto‑1 expression in glioma cells. This observation may provide novel targets for the prevention and treatment of gliomas.

A Review: Proteomics in Nasopharyngeal Carcinoma

Although radiotherapy is generally effective in the treatment of major nasopharyngeal carcinoma (NPC), this treatment still makes approximately 20% of patients radioresistant. Therefore, the identification of blood or biopsy biomarkers that can predict the treatment response to radioresistance and that can diagnosis early stages of NPC would be highly useful to improve this situation. Proteomics is widely used in NPC for searching biomarkers and comparing differentially expressed proteins. In this review, an overview of proteomics with different samples related to NPC and common proteomics methods was made. In conclusion, identical proteins are sorted as follows: Keratin is ranked the highest followed by such proteins as annexin, heat shock protein, 14-3-3σ, nm-23 protein, cathepsin, heterogeneous nuclear ribonucleoproteins, enolase, triosephosphate isomerase, stathmin, prohibitin, and vimentin. This ranking indicates that these proteins may be NPC-related proteins and have potential value for further studies.

Genetic variants modulating CRIPTO serum levels identified by genome-wide association study in Cilento isolates

Cripto, the founding member of the EGF-CFC genes, plays an essential role in embryo development and is involved in cancer progression. Cripto is a GPI-anchored protein that can interact with various components of multiple signaling pathways, such as TGF-β, Wnt and MAPK, driving different processes, among them epithelial-mesenchymal transition, cell proliferation, and stem cell renewal. Cripto protein can also be cleaved and released outside the cell in a soluble and still active form. Cripto is not significantly expressed in adult somatic tissues and its re-expression has been observed associated to pathological conditions, mainly cancer. Accordingly, CRIPTO has been detected at very low levels in the plasma of healthy volunteers, whereas its levels are significantly higher in patients with breast, colon or glioblastoma tumors. These data suggest that CRIPTO levels in human plasma or serum may have clinical significance. However, very little is known about the variability of serum levels of CRIPTO at a population level and the genetic contribution underlying this variability remains unknown. Here, we report the first genome-wide association study of CRIPTO serum levels in isolated populations (n = 1,054) from Cilento area in South Italy. The most associated SNPs (p-value<5*10-8) were all located on chromosome 3p22.1-3p21.3, in the CRIPTO gene region. Overall six CRIPTO associated loci were replicated in an independent sample (n = 535). Pathway analysis identified a main network including two other genes, besides CRIPTO, in the associated regions, involved in cell movement and proliferation. The replicated loci explain more than 87% of the CRIPTO variance, with 85% explained by the most associated SNP. Moreover, the functional analysis of the main associated locus identified a causal variant in the 5’UTR of CRIPTO gene which is able to strongly modulate CRIPTO expression through an AP-1-mediate transcriptional regulation.

Cripto gene has a fundamental role in embryo development and is also involved in cancer. The protein is bound to the cell membrane through an anchor, that can be cleaved, causing the secretion of the protein, in a still active form. In the adult, CRIPTO is detected at very low levels in normal tissues and in the blood, while its increase in both tissues and blood is associated to pathological conditions, mainly cancer. As other GPI linked proteins such as the carcinoembryonic antigen (CEA), one of the most used tumor markers, CRIPTO is able to reach the bloodstream. Therefore, CRIPTO represents a new promising biomarker and potential therapeutic target, and blood CRIPTO levels might be associated to clinical features. Here we examined the variability of blood CRIPTO levels at a population level (population isolates from the Cilento region in South Italy) and we investigated the genetic architecture underlying this variability. We reported the association of common genetic variants with the levels of CRIPTO protein in the blood and we identified a main locus on chromosome 3 and additional five associated loci. Moreover, through functional analyses, we were able to uncover the mechanism responsible for the variation in CRIPTO levels, which is a regulation mediated by the transcriptional factor AP-1.

Cripto haploinsufficiency affects in vivo colon tumor development

Colorectal cancer is one of the most common and aggressive cancers arising from alterations in various signaling pathways, such as the WNT, RAS-MAPK, PI3K and transforming growth factor-β (TGF-β) pathways. Cripto (also called Teratocarcinoma-derived growth factor), the original member of the vertebrate EGF-CFC family, plays a key role in all of these pathways and is deeply involved in early embryo development and cancer progression. The role of Cripto in colon and breast cancer, in particular, has been investigated, as it is still not clearly understood. In this article, we provide the first in vivo functional evidence of a role of Cripto in colon cancer development. We analyzed the effect of Cripto haploinsufficiency on colon tumor formation by treating Cripto heterozygous mice with the colonotropic carcinogen azoxymethane (AOM). Of note, in our model system, Cripto haploinsufficiency increased tumorigenesis. Moreover, we revealed a correlation between the differential AOM response found in wt and Cripto⁺/⁻ mice and the expression levels of glucose regulated protein-78 (Grp78), a heat shock protein required for Cripto signaling pathways. We hypothesize that the balance between Cripto and Grp78 expression levels might be crucial in cancer development and may account for the increased tumorigenesis in Cripto heterozygous mice. In summary, our results highlight the heterogeneous effect of Cripto on tumorigenesis and the consequent high level of complexity in the Cripto regulatory pathway, whose imbalance causes tumors.

Quantitative proteome analysis of overexpressed Cripto-1 tumor cell reveals 14-3-3γ as a novel biomarker in nasopharyngeal carcinoma

We previously found that Cripto-1 is involved in the tumorigenesis of nasopharyngeal carcinoma (NPC). Here, to identify new NPC related proteins and to investigate the clinicopathological correlations of it in NPC, Cripto-1 over-expressed cell (CNE1/CR1(+)) was established. Two-dimensional difference in gel electrophoresis (2D-DIGE) analysis and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF MS) were used to identify 23 differential proteins in CNE1/CR1(+) and parental cells. Among them, 14-3-3γ showed the potential to be a NPC related protein. 14-3-3γ expression was found in 58.3% (60/103) tumor tissues as detected by IHC, and 69.6% (16/23) NPC fresh tumors expressed higher 14-3-3γ than paired non-cancerous tissues as detected by Western blot. Moreover, 14-3-3γ expression was positively correlated with N classification (p=0.031), distant metastasis (M classification, p=0.018) and clinical stage (p=0.046) of NPC patients. As determined by the Kaplan-Meier method, 14-3-3γ expression in NPC was significantly associated with overall survival (p=0.015). Multivariate analysis also showed that the expression of 14-3-3γ protein was an independent prognostic factor for outcome of NPC. In this study, we identified upregulated 14-3-3γ by 2D-DIGE in CNE1/CR-1(+). We also demonstrated that 14-3-3γ might be a potential biomarker for the prognosis of patients with NPC.

BIOLOGICAL SIGNIFICANCE

We believe that three aspects of this manuscript will make it interesting to general readers of Journal of Proteomics. Firstly, based on our previous report, we further validated that Cripto-1 can promote the proliferation and invasion of nasopharyngeal carcinoma (NPC). In this context, we used 2D-DIGE to identify new NPC related proteins. As a result, 14-3-3γ showed the potential to be a candidate. Secondly, we reported for the first time that the expression level of 14-3-3γ was significantly increased in human NPC patient tissues, and 14-3-3γ overexpression correlated statistically with N classification, distant metastasis, and clinical stage. Our results highlight the clinical significance of 14-3-3γ in NPC. Finally, we found that high 14-3-3γ expression is associated with poor survival in NPC patients. Thus, this study has identified that the 14-3-3γ involves in the carcinogenesis of NPC. Our findings may also provide new insights into understanding the molecular mechanism involved in NPC carcinogenesis and progression, and may lead to the development of new approaches for effective diagnosis and therapy.

Human recombinant Cripto-1 increases doubling time and reduces proliferation of HeLa cells independent of pro-proliferation pathways

Human oncofetal protein Cripto-1 (CR-1) is overexpressed in many types of cancers. CR-1 binds to cell surface Glypican-1 to activate Erk1/2 MAPK and Akt pathways leading to cell proliferation. However, we show that treatment with recombinant CR-1 reduces proliferation of HeLa cells by increasing the doubling time without triggering cell death or cell cycle arrest. Using a comparative study with U-87 MG cells, we show that the pro-proliferative pathway of CR-1 is not effective in HeLa cells due to lower expression of Glypican-1. Further we show that treatment with recombinant CR-1 increases PTEN in HeLa cells leading to downregulation of PI3K/Akt pathway. The anti-proliferative effect gets potentiated when the pro-proliferative pathway is blocked.

Silencing of c-Met by RNA interference inhibits the survival, proliferation, and invasion of nasopharyngeal carcinoma cells

c-Met is a tyrosine kinase receptor that mediates pleiotropic cellular responses following its activation by hepatocyte growth factor. The overexpression of c-Met in nasopharyngeal carcinoma (NPC) has been described recently, but the functional role of c-Met in NPC remains incompletely understood. This study aimed to investigate the potential mechanism by which c-Met contributes to the tumorigenesis of NPC. In the present study, by using RNA interference we silenced the expression of c-Met in CNE-2 cells, a poorly differentiated NPC cell line. Our in vitro studies showed that shRNA-mediated depletion of c-Met resulted in the suppression of proliferation, migration, and invasion, as well as an increase in the apoptosis of CNE-2 cells. Moreover, in xenograft nude mice we demonstrated that the depletion of c-Met resulted in reduced tumor growth and increased apoptosis in xenografts. Taken together, these results suggest that c-Met plays an oncogenic role in the development of NPC and reveal it as a potential novel therapeutic target for NPC.

The role of Cripto-1 in the tumorigenesis and progression of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC), the most common malignancy of the oral cavity, remains a lethal disease in over 50% of cases diagnosed annually, due mostly to late detection of this cancer in its advanced stages despite the easy accessibility of the oral cavity for regular examinations. Cripto-1 is a member of the epidermal growth factor (EGF)-CFC protein family and is involved in the activation of several different signaling pathways during embryonic development and cellular transformation. Although the Cripto-1 protein is overexpressed in several human cancers including breast, colon, cervix, gastric, and pancreatic cancer, no prior study has evaluated Cripto-1 expression in OSCC. Therefore, our aims in this study were to examine Cripto-1 expression in clinical samples of OSCC patients using immunohistochemistry, to analyze the correlation between Cripto-1 expression and clinicopathologic parameters, and to identify the oncogenic roles of Cripto-1 in OSCC cell lines. Both epithelial dysplasia (73.3%) and OSCC (55.5%) tissue samples showed significantly higher expression of Cripto-1 than normal mucosa (20%) (p=0.031). In the OSCC samples, there was a significant correlation between Cripto-1 expression and the histological differentiation of OSCC (p=0.015) and a high PCNA index (p=0.011). The in vitro cell proliferation assays demonstrated that recombinant human Cripto-1 (rhCripto-1) induced both SCC-4 and SCC-25 cells to proliferate as compared with control cells (p<0.05 and p<0.01, respectively). In in vitro migration assays, treatment of SCC-4 and SCC-25 cells with rhCripto-1 protein induced a 2.4-fold and 1.7-fold-increase in cell migration, respectively (p=0.000 and p=0.008, respectively). Taken together, our data suggest that Cripto-1 plays a role in the malignant transformation of the oral mucosa and is involved in the tumorigenesis and progression of OSCC by promoting the growth and migration of malignant cells.

Alantolactone Inhibits Cell Proliferation by Interrupting the Interaction between Cripto-1 and Activin Receptor Type II A in Activin Signaling Pathway

It has been suggested that deregulation of activin signaling contributes to tumor formation. Activin signaling is blocked in cancer cells due to the complex formed by Cripto-1, activin, and activin receptor type II (ActRII). In this study, the authors used a mammalian two-hybrid system to construct a drug screening model to obtain a small molecular inhibitor capable of interrupting the interaction between Cripto-1 and ActRII. They screened 300 natural components and identified alantolactone. Data suggested that alantolactone induced activin/SMAD3 signaling in human colon adenocarcinoma HCT-8 cells. The authors also found that alantolactone exhibited antiproliferative function specific to tumor cells, with almost no toxicity to normal cells at a concentration of 5 µg/mL. Furthermore, they proved that the antiproliferative function of alantolactone was activin/SMAD3 dependent. These results suggest that alantolactone performs its antitumor effect by interrupting the interaction between Cripto-1 and the activin receptor type IIA in the activin signaling pathway. Moreover, screening for inhibitors of Cripto-1/ActRII is a potentially beneficial approach to aid in discovering novel cancer treatment.

Cripto-1: an embryonic gene that promotes tumorigenesis

Several studies have shown that cell fate regulation during embryonic development and oncogenic transformation share common regulatory mechanisms and signaling pathways. Indeed, an embryonic gene member of the EGF–Cripto-1/FRL1/Cryptic family, Cripto-1, has been implicated in embryogenesis and in carcinogenesis. Cripto-1 together with the TGF-β ligand Nodal is a key regulator of embryonic development and is a marker of undifferentiated human and mouse embryonic stem cells. While Cripto-1 expression is very low in normal adult tissues, Cripto-1 is re-expressed at high levels in several different human tumors, modulating cancer cell proliferation, migration, epithelial-to-mesenchymal transition and stimulating tumor angiogenesis. Therefore, inhibition of Cripto-1 expression using blocking antibodies or antisense expression vectors might be a useful modality not only to target fully differentiated cancer cells but also to target a subpopulation of tumor cells with stem-like characteristics.