Identification of Cripto-1 as a Novel Serologic Marker for Breast and Colon Cancer

CRIPTO's multifaceted role in driving aggressive prostate cancer unveiled by in vivo, organoid, and patient data

CRIPTO (or CR-1 or TDGF1) is a protein that plays an active role in tumor initiation and progression. We have confirmed that increased expression of CRIPTO is associated with clinical and prostate-specific antigen (PSA) progression in human prostate tissues. Our approach involved gaining insight into the role of CRIPTO signaling in castration-resistant Nkx3.1-expressing cells (CARNs), targets for oncogenic transformation in prostate cancer (PCa), by integrating the existing Criptoflox/flox into CARNs model. The most aggressive stage was modeled using an inducible Cre under control of the Nkx3.1 promoter conferring Nkx3.1 inactivation and driving Pten inactivation, oncogenic Kras activation, and lineage tracing with yellow fluorescence protein (EYFP) upon induction. Our findings provide evidence that selective depletion of Cripto in epithelial cells in vivo reduced the invasive phenotype, particularly in more advanced tumor stages. Moreover, in vitro experiments with Cripto overexpression demonstrated alterations in the physical features of organoids, which correlated with increased tumorigenic activity. Transcriptomic analyses revealed a unique CRIPTO/MYC co-activation signature associated with PSA progression in a human PCa cohort. Taken together, our data highlights a role for CRIPTO in tumor invasiveness and progression, which carries implications for biomarkers and targeted therapies.

Human Cripto-1 and Cripto-3 Protein Expression in Normal and Malignant Settings That Conflicts with Established Conventions

Background/Objectives: Cripto-1 (CR1) is a plurifunctional embryonic protein required for implantation and re-expressed in the adult during wound repair, inflammation, and tumorigenesis. CR1 and its predicted CR1 pseudogene product Cripto-3/CR3 are highly homologous proteins, and given this physical attribute, commercially available antibodies cannot discriminate between CR1 and CR3. Methods: A series of mouse monoclonal antibodies [MoAbs] were developed with a high-affinity binding that can differentiate human CR1/CR3 proteins and showed no measurable cross-reactivity. Results: Using these reagents, we confirm that CR3 is a bona fide translated protein found in human tumor tissue, cancer cell lysates, and in normal/cancer patient donor sera. We also reveal that CR1 and CR3 compete for binding to signal transduction protein Nodal, glucose-regulated protein 78Da (GRP78), and activin receptor-like kinase 4 (Alk4). Our discriminatory MoAbs provide new reagents to help clarify current CR1/CR3 protein expression vagaries in the Cripto field of study, challenging established CR1 conventions. In addition, our data validate CR3 involvement in human carcinogenesis and cell signaling pathways, with potential clinical relevance in determining cancer patient prognosis and disease severity.

Nucleic acid vaccines-based therapy for triple-negative breast cancer: A new paradigm in tumor immunotherapy arena

Nucleic acid vaccines (NAVs) have the potential to be economical, safe, and efficacious. Furthermore, just the chosen antigen in the pathogen is the target of the immune responses brought on by NAVs. Triple-negative breast cancer (TNBC) treatment shows great promise for nucleic acid-based vaccines, such as DNA (as plasmids) and RNA (as messenger RNA [mRNA]). Moreover, cancer vaccines offer a compelling approach that can elicit targeted and long-lasting immune responses against tumor antigens. Bacterial plasmids that encode antigens and immunostimulatory molecules serve as the foundation for DNA vaccines. In the 1990s, plasmid DNA encoding the influenza A nucleoprotein triggered a protective and targeted cytotoxic T lymphocyte (CTL) response, marking the first instance of DNA vaccine-mediated immunity. Similarly, in vitro transcribed mRNA was first successfully used in animals in 1990. At that point, mice were given an injection of the gene encoding the mRNA sequence, and the researchers saw the production of a protein. We begin this review by summarizing our existing knowledge of NAVs. Next, we addressed NAV delivery, emphasizing the need to increase efficacy in TNBC.

Understanding the role of Cripto-1 in cancer progression and therapeutic strategies

During the initial stages of gastrulation during embryonic differentiation and wound healing, Cripto-1 is a critical protein for human growth. The epithelial adhesion molecules' downregulation, the mesenchymal overexpression, and mobile proteins are important mechanisms by which Cripto-1 initiates epithelial to mesenchymal transition (EMT). As a result, the function of Cripto-1 for inducing EMT to increase cell migration is advantageous during embryogenesis; however, it is deleterious during the formation, growth, and malignant tumor metastasis. The majority of malignancies are reported to have elevated levels of Cripto-1. Cripto-1 can modify cancerous cells through its function in EMT, which enables these cells to migrate via the extracellular matrix, bloodstream, and lymphatic vessels, on their way for metastasizing to other organs. The goal of this review is to explain what role Cripto-1 plays in common cancers and to summarize how therapeutic strategies are used to interfere with this molecule to target cancers.

Advanced Lab-on-Fiber Optrodes Assisted by Oriented Antibody Immobilization Strategy

Lab-on-fiber (LoF) optrodes offer several advantages over conventional techniques for point-of-care platforms aimed at real-time and label-free detection of clinically relevant biomarkers. Moreover, the easy integration of LoF platforms in medical needles, catheters, and nano endoscopes offer unique potentials for in vivo biopsies and tumor microenvironment assessment. The main barrier to translating the vision close to reality is the need to further lower the final limit of detection of developed optrodes. For immune-biosensing purposes, the assay sensitivity significantly relies on the capability to correctly immobilize the capture antibody in terms of uniform coverage and correct orientation of the bioreceptor, especially when very low detection limits are requested as in the case of cancer diagnostics. Here, we investigated the possibility to improve the immobilization strategies through the use of hinge carbohydrates by involving homemade antibodies that demonstrated a significantly improved recognition of the antigen with ultra-low detection limits. In order to create an effective pipeline for the improvement of biofunctionalization protocols to be used in connection with LoF platforms, we first optimized the protocol using a microfluidic surface plasmon resonance (mSPR) device and then transferred the optimized strategy onto LoF platforms selected for the final validation. Here, we selected two different LoF platforms: a biolayer interferometry (BLI)-based device (commercially available) and a homemade advanced LoF biosensor based on optical fiber meta-tips (OFMTs). As a clinically relevant scenario, here we focused our attention on a promising serological biomarker, Cripto-1, for its ability to promote tumorigenesis in breast and liver cancer. Currently, Cripto-1 detection relies on laborious and time-consuming immunoassays. The reported results demonstrated that the proposed approach based on oriented antibody immobilization was able to significantly improve Cripto-1 detection with a 10-fold enhancement versus the random approach. More interestingly, by using the oriented antibody immobilization strategy, the OFMTs-based platform was able to reveal Cripto-1 at a concentration of 0.05 nM, exhibiting detection capabilities much higher (by a factor of 250) than those provided by the commercial LoF platform based on BLI and similar to the ones shown by the commercial and well-established bench-top mSPR Biacore 8K system. Therefore, our work opened new avenues into the development of high-sensitivity LoF biosensors for the detection of clinically relevant biomarkers in the sub-ng/mL range.

Elevated serum Cripto-1 and VEGF levels in patients with non-small cell lung cancer

Cripto-1 (CR-1) facilitates vascular endothelial growth factor (VEGF) expression, and these markers are associated with various tumor cell proliferation, angiogenesis, and metastasis. The main aim of our study was to investigate the clinical value of CR-1 and VEGF for non-small cell lung cancer (NSCLC) patients. Serum samples were collected from 312 patients with NSCLC and 120 healthy controls. The levels of CR-1 and VEGF were measured by enzyme-linked immunosorbent assay (ELISA). The serum levels of CR-1 and VEGF in NSCLC patients were significantly higher than those of healthy controls (p < 0.05). Elevated CR-1 levels were associated with progression of NSCLC stage and higher CR-1 was detected more in patients with distant metastasis (p < 0.05). Patients exhibiting low levels of serum CR-1 had better overall survival than those with high levels (p < 0.05). The CR-1 levels of NSCLC patients with postoperative recurrent were higher than those of nonrecurrent NSCLC patients. Our study suggests that serum CR-1 and VEGF are useful biomarker for NSCLC patients.

TGF-β superfamily co-receptors in cancer

Transforming growth factor-β (TGF-β) superfamily signaling via their cognate receptors is frequently modified by TGF-β superfamily co-receptors. Signaling through SMAD-mediated pathways may be enhanced or depressed depending on the specific co-receptor and cell context. This dynamic effect on signaling is further modified by the release of many of the co-receptors from the membrane to generate soluble forms that are often antagonistic to the membrane-bound receptors. The co-receptors discussed here include TβRIII (betaglycan), endoglin, BAMBI, CD109, SCUBE proteins, neuropilins, Cripto-1, MuSK, and RGMs. Dysregulation of these co-receptors can lead to altered TGF-β superfamily signaling that contributes to the pathophysiology of many cancers through regulation of growth, metastatic potential, and the tumor microenvironment. Here we describe the role of several TGF-β superfamily co-receptors on TGF-β superfamily signaling and the impact on cellular and physiological functions with a particular focus on cancer, including a discussion on recent pharmacological advances and potential clinical applications targeting these co-receptors.

Whence CRIPTO: The Reemergence of an Oncofetal Factor in 'Wounds' That Fail to Heal

There exists a set of factors termed oncofetal proteins that play key roles in ontogeny before they decline or disappear as the organism's tissues achieve homeostasis, only to then re-emerge in cancer. Although the unique therapeutic potential presented by such factors has been recognized for more than a century, their clinical utility has yet to be fully realized1. This review highlights the small signaling protein CRIPTO encoded by the tumor derived growth factor 1 (TDGF1/Tdgf1) gene, an oft cited oncofetal protein whose presence in the cancer literature as a tumor promoter, diagnostic marker and viable therapeutic target continues to grow. We touch lightly on features well established and well-reviewed since its discovery more than 30 years ago, including CRIPTO's early developmental roles and modulation of SMAD2/3 activation by a selected set of transforming growth factor β (TGF-β) family ligands. We predominantly focus instead on more recent and less well understood additions to the CRIPTO signaling repertoire, on its potential upstream regulators and on new conceptual ground for understanding its mode of action in the multicellular and often stressful contexts of neoplastic transformation and progression. We ask whence it re-emerges in cancer and where it 'hides' between the time of its fetal activity and its oncogenic reemergence. In this regard, we examine CRIPTO's restriction to rare cells in the adult, its potential for paracrine crosstalk, and its emerging role in inflammation and tissue regeneration-roles it may reprise in tumorigenesis, acting on subsets of tumor cells to foster cancer initiation and progression. We also consider critical gaps in knowledge and resources that stand between the recent, exciting momentum in the CRIPTO field and highly actionable CRIPTO manipulation for cancer therapy and beyond.

miR-3929 Inhibits Proliferation and Promotes Apoptosis by Downregulating Cripto-1 Expression in Cervical Cancer Cells

Cripto-1 is highly expressed in many cancers, and downregulating its expression may become a promising approach for cancer treatment. However, the regulation of Cripto-1 expression is not well characterized. In this study, we focused on the post-transcriptional regulation of Cripto-1 expression and analyzed the potential miRNAs that bind to the 3'UTR of Cripto-1 mRNA. miR-3929 was found to be able to bind to the 3'UTR and downregulate the expression of Cripto-1 in cervical cancer cells. Then, we analyzed the effect of miR-3929 on the biological behavior of cervical cancer cells, finding that miR-3929 could reduce cell viability, DNA synthesis, and Ki67 expression and induce cell cycle arrest in the G2/M phase; overexpression of Cripto-1 reversed the inhibitory effect of miR-3929 on proliferation. Moreover, DAPI staining and flow cytometry revealed that miR-3929-induced cell apoptosis is dependent on the mitochondrial pathway; the overexpression of Cripto-1 reversed the proapoptotic effect of miR-3929. Finally, the in vivo results showed that miR-3929 significantly inhibits the growth of HeLa xenograft tumors in nude mice. Therefore, our findings suggest that miR-3929 inhibits the proliferation and induces the apoptosis of cervical cancer cells by downregulating Cripto-1 via specifically targeting the 3'UTR of its mRNA.

Cripto-1 as a Key Factor in Tumor Progression, Epithelial to Mesenchymal Transition and Cancer Stem Cells

Cripto-1 is an essential protein for human development that plays a key role in the early phase of gastrulation in the differentiation of an embryo as well as assists with wound healing processes. Importantly, Cripto-1 induces epithelial to mesenchymal transition to turn fixed epithelial cells into a more mobile mesenchymal phenotype through the downregulation of epithelial adhesion molecules such as E-cadherin, occludins, and claudins, and the upregulation of mesenchymal, mobile proteins, such as N-cadherin, Snail, and Slug. Consequently, Cripto-1’s role in inducing EMT to promote cell motility is beneficial in embryogenesis, but detrimental in the formation, progression and metastasis of malignant tumors. Indeed, Cripto-1 is found to be upregulated in most cancers, such as breast, lung, gastrointestinal, hepatic, renal, cervical, ovarian, prostate, and skin cancers. Through its role in EMT, Cripto-1 can remodel cancer cells to enable them to travel through the extracellular matrix as well as blood and lymphatic vessels to metastasize to different organs. Additionally, Cripto-1 promotes the survival of cancer stem cells, which can lead to relapse in cancer patients.

Exosomal Cripto-1 Serves as a Potential Biomarker for Perihilar Cholangiocarcinoma

Perihilar cholangiocarcinoma (PHCCA) has a poor prognosis, mainly due to diagnosis at an advanced stage. Cripto-1 functions as an oncogene and is highly expressed in several human cancers, however, its clinical application in PHCCA is poorly understood. Herein, we identified that Cripto-1 was released by PHCCA cells via exosomes in vitro and in vivo. Furthermore, an ELISA method was developed to detect exosomal Cripto-1 in the serum of 115 PHCCA patients, 47 cholangitis patients and 65 healthy controls, and it was found that exosomal Cripto-1 was increased in PHCCA patients and associated with metastasis. Compared with traditional serum tumor markers, CA19-9 and CEA, exosomal Cripto-1 demonstrated a larger area under ROC curve for PHCCA diagnosis. The cutoff value of exosomal Cripto-1 was 0.82, achieving a sensitivity of 79.1% and a specificity of 87.5%. As expected, exosomal Cripto-1 levels in immunohistochemically Cripto-1-high cases were significantly elevated compared to in Cripto-1-low cases. When measured 1-week postoperatively, Cripto-1 levels decreased on average from 1.25(0.96-3.26) to 0.85(0.62-1.82). Immunohistochemistry analysis showed Cripto-1 expression was negatively correlated with E-cadherin and was an independent prognostic biomarker for poor survival in PHCCA patients. In conclusion, exosomal Cripto-1 in sera can reflect its expression in the tissue of PHCAA patients and has the potential be a non-invasive biomarker for diagnosis and prognosis of PHCCA.

Cripto favors chondrocyte hypertrophy via TGF-β SMAD1/5 signaling during development of osteoarthritis

Chondrocytes in mice developing osteoarthritis (OA) exhibit an aberrant response to the secreted cytokine transforming growth factor (TGF)‐β, consisting in a potentiation of intracellular signaling downstream of the transmembrane type I receptor kinase activin receptor‐like kinase (ALK)1 against canonical TGF‐β receptor ALK5‐mediated signaling. Unfortunately, the underlying mechanisms remain elusive. In order to identify novel druggable targets for OA, we aimed to investigate novel molecules regulating the ALK1/ALK5 balance in OA chondrocytes. We performed gene expression analysis of TGF‐β signaling modulators in joints from three different mouse models of OA and found an upregulated expression of the TGF‐β co‐receptor Cripto (Tdgf1), which was validated in murine and human cartilage OA samples at the protein level. In vitro and ex vivo, elevated expression of Cripto favors the hypertrophic differentiation of chondrocytes, eventually contributing to tissue calcification. Furthermore, we found that Cripto participates in a TGF‐β–ALK1–Cripto receptor complex in the plasma membrane, thereby inducing catabolic SMAD1/5 signaling in chondrocytes. In conclusion, we demonstrate that Cripto is expressed in OA and plays a functional role promoting chondrocyte hypertrophy, thereby becoming a novel potential therapeutic target in OA, for which there is no efficient cure or validated biomarker. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

New Insights into Cancer Targeted Therapy: Nodal and Cripto-1 as Attractive Candidates

The transforming growth factor beta (TGF-β) signaling is fundamental for correct embryonic development. However, alterations of this pathway have been correlated with oncogenesis, tumor progression and sustaining of cancer stem cells (CSCs). Cripto-1 (CR-1) and Nodal are two embryonic proteins involved in TGF-β signaling. Their expression is almost undetectable in terminally differentiated cells, but they are often re-expressed in tumor cells, especially in CSCs. Moreover, cancer cells that show high levels of CR-1 and/or Nodal display more aggressive phenotypes in vitro, while in vivo their expression correlates with a worse prognosis in several human cancers. The ability to target CSCs still represents an unmet medical need for the complete eradication of certain types of tumors. Given the prognostic role and the selective expression of CR-1 and Nodal on cancer cells, they represent archetypes for targeted therapy. The aim of this review is to clarify the role of CR-1 and Nodal in cancer stem populations and to summarize the current therapeutic strategy to target CSCs using monoclonal antibodies (mAbs) or other molecular tools to interfere with these two proteins.

Expression of Cripto-1 predicts poor prognosis in stage I non-small cell lung cancer

Cripto-1 (CR-1) is related to the biological behaviour and prognosis of carcinomas. The purpose of this study was to investigate the significance of CR-1 expression in surgically resected stage I non-small cell lung cancer (NSCLC). One hundred and forty-eight patients with completely resected stage I NSCLC and available clinical follow-up data were assessed. The protein expression of CR-1 in the tumours was detected by immunohistochemistry. CR-1 was highly expressed in 64 of 148 tumours. Among patients with high CR-1 expression, progression-free survival and overall survival rate were significantly lower than those of patients with low CR-1 levels (P = .013 and P = .019, respectively). The incidence of distant metastasis in patients with high CR-1 expression was significantly higher than that of in patients with low CR-1 expression (57.13% vs 21.43%, P = .001). The results of the multivariate analysis confirmed that a high CR-1 was a significant factor for poor prognosis. In conclusion, CR-1 could be a useful prognostic factor in patients with stage I NSCLC, likely as an indicator of the metastatic propensity of the tumour.

Role of Oncofetal Protein CR-1 as a Potential Tumor Marker for Oral Squamous Cell Carcinoma

Cripto-1 (CR-1) is an oncofetal protein with its role as a key factor in early process of carcinoma has been evaluated in cases of various cancers. However, very few studies have reported its role in oral cancer, which is the sixth most common cancer around the world, particularly with high prevalence in developing countries. Oral squamous cell carcinoma (OSCC) is the most predominant (90%) of all the histological types of oral cancer. Late detection, associated with increased morbidity and mortality, is mainly attributed to non-availability of a suitable biomarker for the disease. In the present pilot study, we have evaluated the role of soluble CR-1, in serum as a potential tumor marker for OSCC. CR-1 was estimated using sandwich ELISA in serum samples of 50 biopsy proven OSCC patients (pre and post treatment) along with age and gender matched healthy controls. Immunohistochemistry was also done in corresponding tumor tissue sections to check the expression of CR-1. Pre-treatment CR-1 was found to be 2.25-fold higher in serum of OSCC patients as compared to control (p < 0.0001***), which was reduced to 1.6 folds post treatment (p = 0.0006***). CR-1 levels were comparatively higher in early stage of disease. Upon IHC 80% of the cases were found to be positive for CR-1. This study provides evidence that serum levels of CR-1 are elevated in patients of Oral Squamous Cell Carcinoma, which decrease post treatment. Also, the association of expression of protein with tumor progression predicts CR-1 as a molecule that can be further evaluated as a potential tumor maker in OSCC.

A Multidisciplinary Review of the Roles of Cripto in the Scientific Literature Through a Bibliometric Analysis of its Biological Roles

Cripto is a small glycosylphosphatidylinisitol (GPI)-anchored and secreted oncofetal protein that plays important roles in regulating normal physiological processes, including stem cell differentiation, embryonal development, and tissue growth and remodeling, as well as pathological processes such as tumor initiation and progression. Cripto functions as a co-receptor for TGF-β ligands such as Nodal, GDF1, and GDF3. Soluble and secreted forms of Cripto also exhibit growth factor-like activity and activate SRC/MAPK/PI3K/AKT pathways. Glucose-Regulated Protein 78 kDa (GRP78) binds Cripto at the cell surface and has been shown to be required for Cripto signaling via both TGF-β and SRC/MAPK/PI3K/AKT pathways. To provide a comprehensive overview of the scientific literature related to Cripto, we performed, for the first time, a bibliometric analysis of the biological roles of Cripto as reported in the scientific literature covering the last 10 years. We present different fields of knowledge in comprehensive areas of research on Cripto, ranging from basic to translational research, using a keyword-driven approach. Our ultimate aim is to aid the scientific community in conducting targeted research by identifying areas where research has been conducted so far and, perhaps more importantly, where critical knowledge is still missing.

Serum CRIPTO does not confer drug resistance against osimertinib but is an indicator of tumor burden in non-small cell lung cancer

BACKGROUND

Adenocarcinoma is the most common subtype of non-small cell lung cancer (NSCLC) and often harbors oncogenic driver mutations in the epidermal growth factor receptor (EGFR). Osimertinib (AZD9291), a third generation EGFR TKI, has replaced earlier generation EGFR TKIs for first line treatment of EGFR mutant lung cancer due to its improved overall survival, longer progression free survival, and better tolerability compared to earlier generation inhibitors. However, like earlier generation EGFR TKIs, only about two thirds of patients respond, indicating an unknown mechanism of intrinsic resistance for the non-responders. We previously identified overexpression of CRIPTO as a potential mechanism of intrinsic resistance to EGFR TKIs of first and second generation.

OBJECTIVE

To determine if CRIPTO could promote drug resistance against the third generation EGFR-TKIs osimertinib. We also wanted to investigate whether this resistance was conferred by both membrane bound and secreted CRIPTO. Finally, we wanted to explore the potential of secreted CRIPTO as a non-invasive biomarker for EGFR-TKI resistance.

MATERIALS AND METHODS

HCC827 and H1975, EGFR mutant non-small cell lung carcinoma (NSCLC) cell lines, were transfected with wildtype CRIPTO, two secreted variants of CRIPTO, a membrane only version of CRIPTO, and the mock backbone vector as the control. Western blotting, immunoprecipitation, and in vitro viability experiments were performed. In vivo work was carried out in athymic nude mice; 2 × 10⁶ CRIPTO overexpressing HCC827 cells were implanted per mouse. EGFR mutant NSCLC patient blood samples were collected before treatment with and EGFR-TKI, during response while on treatment, and at progression while on treatment.

RESULTS

Although both membrane bound and secreted CRIPTO forms were able to activate downstream pathways such as SRC, CRIPTO was unable to elicit resistance towards osimertinib in vitro or in vivo. CRIPTO serum levels in mice were higher in larger xenograft tumors. Furthermore, CRIPTO serum levels were higher in patients with progressing lung cancer when compared to their CRIPTO serum levels during EGFR-TKI response.

CONCLUSIONS

CRIPTO does not cause resistance against third generation EGFR-TKI osimertinib. CRIPTO levels in serum might be a potentially useful biomarker for tumor burden in NSCLC patients.

CRIPTO and miR-371a-3p Are Serum Biomarkers of Testicular Germ Cell Tumors and Are Detected in Seminal Plasma from Azoospermic Males

miR-371a-3p is currently the most informative reported biomarker for germ cell tumors (GCTs). Another developmental-related biomarker, CRIPTO, is involved in the regulation of pluripotency and germ cell fate commitment. We aimed to assess the value of CRIPTO as a diagnostic and prognostic biomarker of testicular GCTs (TGCTs) and also to assess its presence in seminal plasma samples, compared with miR-371a-3p. In total, 217 and 94 serum/seminal plasma samples were analyzed. CRIPTO was quantified using ELISA and miR-371a-3p using bead-based isolation followed by RT-qPCR. Methylation profiling (EPIC array) for the CRIPTO promoter region was undertaken in 35 TGCT tissues plus four (T)GCT cell lines. Significantly higher CRIPTO concentration was found in sera of non-seminomas compared to controls (p = 0.0297), and in stage II/III disease compared to stage I (p = 0.0052, p = 0.0097). CRIPTO concentration was significantly positively correlated with miR-371a-3p levels in serum (r = 0.16) and seminal plasma (r = 0.40). CRIPTO/miR-371a-3p levels were significantly higher in seminal plasma controls when compared to serum controls (p = 0.0001, p < 0.0001). CRIPTO/miR-371a-3p were detected both in normospermic and azoospermic males, and levels were higher in TGCTs compared to GCNIS-only. We have provided the largest dataset of evaluation of CRIPTO in serum and seminal plasma of GCTs, showing its potential value as a biomarker of the disease.

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.

KRAS mutation and abnormal expression of Cripto-1 as two potential candidate biomarkers for detection of colorectal cancer development

Colorectal cancer (CRC), regardless of standard procedures of treatment and screening, is still considered one of the deadliest cancers in the Western world, and in economically developed Asian countries, especially Iran. The current study was undertaken to investigate whether changes in the level of Cripto-1 (CR-1) expression and KRAS mutations have a cumulative effect on the onset and progression of CRC. Fifty colorectal tissue samples, including 35 colorectal carcinomas with matching adjacent mucosa, and 15 colorectal adenomas, were chosen for analysis. Twenty-five CRC biopsies and 15 adenoma were analyzed for KRAS mutations by DNA sequencing (Sanger sequencing), and all 50 patients (35 CRCs and 15 adenomas) were evaluated by immunohistochemistry for the CR-1 protein expression. The inducible somatic KRAS mutation (G12D) was observed in nine (36%) of CRC patients, and in two (13.3%) of adenoma patients. The CR-1 expression level in both adenomas (P < .05) and carcinomas (P < .001), were significantly different, compared with the matching adjacent mucosa. The intensity of CR-1 staining in adenomas was less than the intensity of staining, detected in the CRCs (P < .001). The G12D KRAS mutation and CR-1 abnormalities are significantly associated as two signature biomarkers with potential clinical characteristics for the detection of CRC development.

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.

Glucocorticoid receptor-dependent induction of cripto-1 (one-eyed pinhead) inhibits zebrafish caudal fin regeneration

We previously used a chemical genetics approach with the larval zebrafish to identify small molecule inhibitors of tissue regeneration. This led to the discovery that glucocorticoids (GC) block early stages of tissue regeneration by the inappropriate activation of the glucocorticoid receptor (GR). We performed a microarray analysis to identify the changes in gene expression associated with beclomethasone dipropionate (BDP) exposure during epimorphic fin regeneration. Oncofetal cripto-1 showed > eight-fold increased expression in BDP-treated regenerates. We hypothesized that the mis-expression of cripto-1 was essential for BDP to block regeneration. Expression of cripto-1 was not elevated in GR morphants in the presence of BDP indicating that cripto-1 induction was GR-dependent. Partial translational suppression of Cripto-1 in the presence of BDP restored tissue regeneration. Retinoic acid exposure prevented increased cripto-1 expression and permitted regeneration in the presence of BDP. We demonstrated that BDP exposure increased cripto-1 expression in mouse embryonic stem cells and that regulation of cripto-1 by GCs is conserved in mammals.

Development of conformational antibodies targeting Cripto-1 with neutralizing effects in vitro

Human Cripto-1 (Cripto-1), the founding member of the EGF-CFC superfamily, is a key regulator of many processes during embryonic development and oncogenesis. Cripto-1 is barely present or even absent in normal adult tissues while it is aberrantly re-expressed in various tumors. Blockade of the CFC domain-mediated Cripto-1 functions is acknowledged as a promising therapeutic intervention point to inhibit the tumorigenic activity of the protein. In this work, we report the generation and characterization of murine monoclonal antibodies raised against the synthetic folded CFC [112-150] domain of the human protein. Through subtractive ELISA assays clones were screened for the ability to specifically recognize "hot spot" residues on the CFC domain, which are crucial for the interaction with Activin Type I receptor (ALK4) and GRP78. On selected antibodies, SPR and epitope mapping studies have confirmed their specificity and have revealed that recognition occurs only on a conformational epitope. Furthermore, FACS analyses have confirmed the ability of 1B4 antibody to recognize the membrane-anchored and soluble native Cripto-1 protein in a panel of human cancer cells. Finally, we have evaluated its functional effects through in vitro cellular signaling assays and cell cycle analysis. These findings suggest that the selected anti-CFC mAbs have the potential to neutralize the protein oncogenic activity and may be used as theranostic molecules suitable as tumor homing agents for Cripto-1-overexpressing cancer cells and tissues and to overcome drug-resistance in routine cancer therapies.

Exogenous Cripto-1 Suppresses Self-Renewal of Cancer Stem Cell Model

Cripto-1 is a glycophosphatidylinositol (GPI) anchored signaling protein of epidermal growth factor (EGF)-Cripto-1-FRL1-Cryptic (CFC) family and plays a significant role in the early developmental stages and in the different types of cancer cells, epithelial to mesenchymal transition and tumor angiogenesis. Previously, we have developed cancer stem cells (miPS-LLCcm) from mouse iPSCs by culturing them in the presence of conditioned medium of Lewis Lung Carcinoma (LLC) cells for four weeks. Nodal and Cripto-1 were confirmed to be expressed in miPS-LLCcm cells by quantitative reverse transcription PCR (rt-qPCR) implying that Cr-1 was required in maintaining stemness. To investigate the biological effect of adding exogenous soluble CR-1 to the cancer stem cells, we have prepared a C-terminally truncated soluble form of recombinant human CR-1 protein (rhsfCR-1), in which the GPI anchored moiety was removed by substitution of a stop codon through site-directed mutagenesis. rhsfCR-1 effectively suppressed the proliferation and sphere forming ability of miPS-LLCcm cells in a dose-dependent manner in the range of 0 to 5 µg/mL, due to the suppression of Nodal-Cripto-1/ALK4/Smad2 signaling pathway. Frequency of sphere-forming cells was dropped from 1/40 to 1/69 by rhsfCR-1 at 1 µg/mL. Moreover, rhsfCR-1 in the range of 0 to 1 µg/mL also limited the differentiation of miPS-LLCcm cells into vascular endothelial cells probably due to the suppression of self-renewal, which should reduce the number of cells with stemness property. As demonstrated by a soluble form of exogenous Cripto-1 in this study, the efficient blockade would be an attractive way to study Cripto-1 dependent cancer stem cell properties for therapeutic application.

Cripto-1 Plasmid DNA Vaccination Targets Metastasis and Cancer Stem Cells in Murine Mammary Carcinoma

Metastatic breast cancer is a fatal disease that responds poorly to treatment. Cancer vaccines targeting antigens expressed by metastatic breast cancer cells and cancer stem cells could function as anticancer therapies. Cripto-1 is an oncofetal protein overexpressed in invasive breast cancer and cancer-initiating cells. In this study, we explored the potential of a Cripto-1-encoding DNA vaccine to target breast cancer in preclinical mouse models. BALB/c mice and BALB-neuT mice were treated with a DNA vaccine encoding mouse Cripto-1 (mCr-1). BALB/c mice were challenged with murine breast cancer 4T1 cells or TUBO spheres; BALB-neuT mice spontaneously developed breast cancer. Tumor growth was followed in all mouse models and lung metastases were evaluated. In vitro assays were performed to identify the immune response elicited by vaccination. Vaccination against mCr-1 reduced primary tumor growth in the 4T1 metastatic breast cancer model and reduced lung metastatic burden. In BALB-neuT mice, because the primary tumors are Cripto-1 negative, vaccination against mCr-1 did not affect primary tumors but did reduce lung metastatic burden. Spheroid-cultured TUBO cells, derived from a BALB/neuT primary tumor, develop a cancer stem cell-like phenotype and express mCr-1. We observed reduced tumor growth in vaccinated mice after challenge with TUBO spheres. Our data indicate that vaccination against Cripto-1 results in a protective immune response against mCr-1 expressing and metastasizing cells. Targeting Cripto-1 by vaccination holds promise as an immunotherapy for treatment of metastatic breast cancer. Cancer Immunol Res; 6(11); 1417-25. ©2018 AACR.

High level of serum Cripto-1 in hepatocellular carcinoma, especially with hepatitis B virus infection

BACKGROUND

Human Cripto-1 (CR-1), a member of the epidermal growth factor-Cripto-1/FRL-1/Cryptic protein family (EGF-CFC), is highly expressed in a variety of human cancers. We aimed to detect serum CR-1 level in liver diseases especially in hepatocellular carcinoma (HCC) patients.

METHODS

Serum CR-1 level was Sandwich-type enzyme-linked immuno sorbent assay (ELISA) detected in 330 patients with liver diseases including HCC, cirrhosis, and chronic hepatitis and 50 volunteers without hepatitis B virus (HBV) or hepatitis C virus (HCV) infection as control.

RESULTS

The serum CR-1 level was significantly higher in HCC patients than volunteer controls and it was also significantly higher in HBV-related HCC than HCV-related HCC. In addition, serum CR-1 level was correlated with serum alpha-feto-protein (AFP) in HBV-related HCC patients. The serum CR-1 was also higher in cirrhosis and chronic hepatitis than volunteer controls. The serum CR-1 in HBV-related cirrhosis was higher than chronic hepatitis B, but there was no significant difference between HCV-related cirrhosis and chronic hepatitis C.

CONCLUSIONS

Serum CR-1 was higher in HCC patients and might serve as a complementary biomarker to clinical diagnosis of HBV-related HCC. The high level of serum CR-1 in HBV-related liver disease might be partly attributed to HBV infection.

Cancer-testis gene PIWIL1 promotes cell proliferation, migration, and invasion in lung adenocarcinoma

Piwi-like RNA-mediated gene silencing 1 (PIWIL1) has been identified as a novel extremely highly expressed cancer-testis (CT) gene in lung adenocarcinoma. However, the exact function and mechanism of PIWIL1 in lung adenocarcinoma remains unclear. Herein, we sought to investigate the role of PIWIL1 in the occurrence and development of lung adenocarcinoma. We examined the expression pattern of PIWIL1 in The Cancer Genome Atlas (TCGA) lung adenocarcinoma samples, and validated it by Real-Time PCR (RT-PCR) in additional 21 paired lung adenocarcinoma tissues and 16 normal tissues. Subsequently, we explored the biological function of PIWIL1 in A549 and H1299 cell lines by gain and loss-of-function analyses. Using TCGA lung adenocarcinoma data, we further performed coexpression and Gene Ontology (GO) analyses, and analyzed the association of DNA methylation levels in PIWIL1 promoter region with its expression. Finally, we evaluated its expression in different mutation status of significantly mutated genes (SMGs) in TCGA lung adenocarcinoma data. We observed that PIWIL1 was expressed in testis and lung adenocarcinoma but not in other normal tissues, and its high expression was associated with shortened survival of lung cancer patients. Overexpression of PIWIL1 could facilitate the proliferation, invasion and migration of lung adenocarcinoma cells and vice versa. GO analysis revealed that PIWIL1 upregulated genes were enriched in embryonic development, cell proliferation and regulation of transcription. Moreover, promoter DNA hypomethylation of PIWIL1 could contribute to its aberrant expression in tumors. Interestingly, PIWIL1 expression was significantly higher in patients without hepatocyte growth factor (HGF) or serine/threonine kinase 11 (STK11) mutation (P = 0.006 and 0.005, respectively). PIWIL1 is an epidriver gene in lung adenocarcinoma, indicating a potential target for further therapy.

Elevated expression of Cripto-1 correlates with poor prognosis in hepatocellular carcinoma

Cripto-1 could promote tumorigenesis in a wide range of carcinomas, yet little is known in hepatocellular carcinoma (HCC). The expression of Cripto-1 and MMP-9 were assessed by immunohistochemistry in 205 HCC specimens. The correlation between Cripto-1 and MMP-9, clinicopathological/prognostic value in HCC was examined. Cripto-1 overexpression was correlated with larger tumor, TNM stage, BCLC stage and tumor recurrence. In multivariate analyses, Cripto-1 was an independent predictor for overall survival (OS) and time to recurrence (TTR). Cripto-1 expression was increased in TNM and BCLC stage-dependent manner. Cripto-1 overexpression was associated with poor prognosis in patients subgroups stratified by tumor size, tumor differentiation, TNM and BCLC stage. In addition, Cripto-1 was positively correlated with MMP-9 among 205 HCC samples. Patients with Cripto-1 upregulation had poor OS and shorter TTR in low and high aggressiveness groups. Furthermore, Cripto-1 had predictive validity for early and late recurrence in HCC patients. Combination of Cripto-1 and serum AFP was correlated with OS and TTR. In conclusion, Cripto-1 overexpression contributes to aggressiveness and poor prognosis of HCC. Cripto-1/AFP expression could be a potential prognostic biomarker for survival in HCC patients.

Identification of Phosphorylated Cyclin-Dependent Kinase 1 Associated with Colorectal Cancer Survival Using Label-Free Quantitative Analyses

Colorectal cancer is the most common form of cancer in the world, and the five-year survival rate is estimated to be almost 90% in the early stages. Therefore, the identification of potential biomarkers to assess the prognosis of early stage colorectal cancer patients is critical for further clinical treatment. Dysregulated tyrosine phosphorylation has been found in several diseases that play a significant regulator of signaling in cellular pathways. In this study, this strategy was used to characterize the tyrosine phosphoproteome of colorectal cell lines with different progression abilities (SW480 and SW620). We identified a total of 280 phosphotyrosine (pTyr) peptides comprising 287 pTyr sites from 261 proteins. Label-free quantitative analysis revealed the differential level of a total of 103 pTyr peptides between SW480 and SW620 cells. We showed that cyclin-dependent kinase I (CDK1) pTyr15 level in SW480 cells was 3.3-fold greater than in SW620 cells, and these data corresponded with the label-free mass spectrometry-based proteomic quantification analysis. High level CDK1 pTyr15 was associated with prolonged disease-free survival for stage II colorectal cancer patients (n = 79). Taken together, our results suggest that the CDK1 pTyr15 protein is a potential indicator of the progression of colorectal cancer.

CRIPTO overexpression promotes mesenchymal differentiation in prostate carcinoma cells through parallel regulation of AKT and FGFR activities

Members of the EGF-CFC (Cripto, FRL-1, Cryptic) protein family are increasingly recognized as key mediators of cell movement and cell differentiation during vertebrate embryogenesis. The founding member of this protein family, CRIPTO, is overexpressed in various human carcinomas. Yet, the biological role of CRIPTO in this setting remains unclear. Here, we find CRIPTO expression as especially high in a subgroup of primary prostate carcinomas with poorer outcome, wherein resides cancer cell clones with mesenchymal traits. Experimental studies in PCa models showed that one notable function of CRIPTO expression in prostate carcinoma cells may be to augment PI3K/AKT and FGFR1 signaling, which promotes epithelial-mesenchymal transition and sustains a mesenchymal state. In the observed signaling events, FGFR1 appears to function parallel to AKT, and the two pathways act cooperatively to enhance migratory, invasive and transformation properties specifically in the CRIPTO overexpressing cells. Collectively, these findings suggest a novel molecular network, involving CRIPTO, AKT, and FGFR signaling, in favor of the emergence of mesenchymal-like cancer cells during the development of aggressive prostate tumors.

Developmental signaling pathways regulating mammary stem cells and contributing to the etiology of triple-negative breast cancer

Cancer has been considered as temporal and spatial aberrations of normal development in tissues. Similarities between mammary embryonic development and cell transformation suggest that the underlying processes required for mammary gland development are also those perturbed during various stages of mammary tumorigenesis and breast cancer (BC) development. The master regulators of embryonic development Cripto-1, Notch/CSL, and Wnt/β-catenin play key roles in modulating mammary gland morphogenesis and cell fate specification in the embryo through fetal mammary stem cells (fMaSC) and in the adult organism particularly within the adult mammary stem cells (aMaSC), which determine mammary progenitor cell lineages that generate the basal/myoepithelial and luminal compartments of the adult mammary gland. Together with recognized transcription factors and embryonic stem cell markers, these embryonic regulatory molecules can be inappropriately augmented during tumorigenesis to support the tumor-initiating cell (TIC)/cancer stem cell (CSC) compartment, and the effects of their deregulation may contribute for the etiology of BC, in particular the most aggressive subtype of BC, triple-negative breast cancer (TNBC). This in depth review will present evidence of the involvement of Cripto-1, Notch/CSL, and Wnt/β-catenin in the normal mammary gland morphogenesis and tumorigenesis, from fMaSC/aMaSC regulation to TIC generation and maintenance in TNBC. Specific therapies for treating TNBC by targeting these embryonic pathways in TICs will be further discussed, providing new opportunities to destroy not only the bulk tumor, but also TICs that initiate and promote the metastatic spread and recurrence of this aggressive subtype of BC.

Serum Cripto-1 is a novel biomarker for non-small cell lung cancer diagnosis and prognosis

INTRODUCTION

Cripto-1 (CR-1) is highly expressed in several different types of human tumors. However, the clinical significance of CR-1 expression in serum specimens from non-small cell lung cancer (NSCLC) patients has not yet been determined.

OBJECTIVES

The aim of this study was to explore the diagnostic and prognostic value of serum CR-1 levels in patients with NSCLC.

METHODS

Serum specimens from 592 NSCLC patients, 180 benign lung disease patients and 240 healthy controls were collected. The concentrations of CR-1 were measured by sandwich enzyme-linked immunosorbent assay.

RESULTS

Patients with NSCLC had higher serum CR-1 levels than the controls (P < 0.01) and patients with benign lung diseases (P < 0.01). When a cutoff point of 1.8 ng/mL was selected (diagnostic specificity 95%), the diagnostic sensitivity for NSCLC is 56.8%. About 37.5% of carcinoembryonic antigen (CEA)-negative lung cancer patients were CR-1 positive at 95% specificity. In patients with stage I/II lung cancer, use of these two markers in combination results in almost 21% increase in sensitivity, at 95% specificity, compared with CEA alone. Uni-variate analysis revealed that NSCLC patients with positive CR-1 had a shorter overall survival (OS) and progression-free survival (PFS) than those with negative CR-1 [hazard ratio (HR) of 2.93, P = 0.005; HR of 2.12, P = 0.005]. Cox multi-variate analysis indicated that CR-1 was an independent prognostic indicator of PFS and OS (HR of 1.91, P = 0.006; HR of 1.82, P = 0.007). Kaplan-Meier survival curves further confirmed that patients with negative CR-1 had longer PFS and OS (P = 0.026 and P = 0.011, respectively).

CONCLUSIONS

In conclusion, measurement of serum CR-1 is a useful diagnostic and prognostic marker for NSCLC patients.

Cripto: Expression, epigenetic regulation and potential diagnostic use in testicular germ cell tumors

Type II germ cell tumors arise after puberty from a germ cell that was incorrectly programmed during fetal life. Failure of testicular germ cells to properly differentiate can lead to the formation of germ cell neoplasia in situ of the testis; this precursor cell invariably gives rise to germ cell cancer after puberty. The Nodal co-receptor Cripto is expressed transiently during normal germ cell development and is ectopically expressed in non-seminomas that arise from germ cell neoplasia in situ, suggesting that its aberrant expression may underlie germ cell dysregulation and hence germ cell cancer. Here we investigated methylation of the Cripto promoter in mouse germ cells and human germ cell cancer and correlated this with the level of CRIPTO protein expression. We found hypomethylation of the CRIPTO promoter in undifferentiated fetal germ cells, embryonal carcinoma and seminomas, but hypermethylation in differentiated fetal germ cells and the differentiated types of non-seminomas. CRIPTO protein was strongly expressed in germ cell neoplasia in situ along with embryonal carcinoma, yolk sac tumor and seminomas. Further, cleaved CRIPTO was detected in media from seminoma and embryonal carcinoma cell lines, suggesting that cleaved CRIPTO may provide diagnostic indication of germ cell cancer. Accordingly, CRIPTO was detectable in serum from 6/15 patients with embryonal carcinoma, 5/15 patients with seminoma, 4/5 patients with germ cell neoplasia in situ cells only and in 1/15 control patients. These findings suggest that CRIPTO expression may be a useful serological marker for diagnostic and/or prognostic purposes during germ cell cancer management.

Serum cripto-1 as a clinical marker for lung cancer

BACKGROUND

Cripto-1 (CR-1) plays an important role in angiogenesis related to tumor growth, in concert with vascular endothelial growth factor (VEGF), and enhanced expression of CR-1 has been reported in lung cancer tissue.

METHODS

Patients with lung cancer (n = 156) and healthy volunteers (n = 60) were enrolled in the study. Serum CR-1 and VEGF concentrations were measured using enzyme-linked immunosorbent assay.

RESULTS

Patients with lung cancer had higher serum CR-1 (4.03 ± 1.49 ng/mL vs. 1.13 ± 0.43 ng/mL, p&lt;0.05) and VEGF (503.62 ± 112.74 pg/mL vs. 398.62 ± 117.84 pg/mL, p&lt;0.05) levels than the control group. With stage progression in non-small cell lung cancer (NSCLC), serum CR-1 levels increased, and patients with distant metastasis had higher levels than those without metastasis (p&lt;0.05). In NSCLC, the low CR-1 group (&lt;1.54 ng/mL) had a better overall survival rate compared with the high CR-1 group (&gt;1.54 ng/mL, p&lt;0.05).

CONCLUSIONS

Our study suggests that serum CR-1 is a useful diagnostic and prognostic marker for NSCLC patients.

Cripto-1 Promotes the Epithelial-Mesenchymal Transition in Esophageal Squamous Cell Carcinoma Cells

Esophageal carcinoma is a major public health problem worldwide and one of the most aggressively malignant neoplasms. Although considerable diagnostic and therapeutic progress has been made in recent years, the prognosis of EC patients still remains dismal due to high rates of recurrence/metastasis and invasion. Previous studies have demonstrated that Epithelial mesenchymal transition (EMT) is proposed as a critical mechanism for the acquisition of malignant phenotypes by epithelial cells. Several lines of evidence have shown that Cripto-1 plays an important oncogenic role during tumorigenesis by promoting EMT. The aim of our study was to evaluate the significance of Cripto-1 which plays a role in EMT and its metastasis in esophageal carcinoma. Data of this study suggest that Cripto-1 overexpression is connected with the tumorigenesis and progression of esophageal carcinoma; shRNA might be feasible for the inhibition of the invasion and metastasis of esophageal carcinoma.

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.

The multifaceted role of the embryonic gene Cripto-1 in cancer, stem cells and epithelial-mesenchymal transition

Cripto-1 (CR-1)/Teratocarcinoma-derived growth factor1 (TDGF-1) is a cell surface glycosylphosphatidylinositol (GPI)-linked glycoprotein that can function either in cis (autocrine) or in trans (paracrine). The cell membrane cis form is found in lipid rafts and endosomes while the trans acting form lacking the GPI anchor is soluble. As a member of the epidermal growth factor (EGF)/Cripto-1-FRL-1-Cryptic (CFC) family, CR-1 functions as an obligatory co-receptor for the transforming growth factor-β (TGF-β) family members, Nodal and growth and differentiation factors 1 and 3 (GDF1/3) by activating Alk4/Alk7 signaling pathways that involve Smads 2, 3 and 4. In addition, CR-1 can activate non-Smad-dependent signaling elements such as PI3K, Akt and MAPK. Both of these pathways depend upon the 78kDa glucose regulated protein (GRP78). Finally, CR-1 can facilitate signaling through the canonical Wnt/β-catenin and Notch/Cbf-1 pathways by functioning as a chaperone protein for LRP5/6 and Notch, respectively. CR-1 is essential for early embryonic development and maintains embryonic stem cell pluripotentiality. CR-1 performs an essential role in the etiology and progression of several types of human tumors where it is expressed in a population of cancer stem cells (CSCs) and facilitates epithelial-mesenchymal transition (EMT). In this context, CR-1 can significantly enhance tumor cell migration, invasion and angiogenesis. Collectively, these facts suggest that CR-1 may be an attractive target in the diagnosis, prognosis and therapy of several types of human cancer.

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.

Cripto-1 expression in glioblastoma multiforme

Human glioblastoma multiforme (GBM) is an aggressive cancer with a very poor prognosis. Cripto-1 (CR-1) has a key regulatory role in embryogenesis, while in adult tissue re-expression of CR-1 has been correlated to malignant progression in solid cancers of non-neuronal origin. As CR-1 expression has yet to be described in cerebral cancer and CR-1 is regulated by signaling pathways dysregulated in GBM, we aimed to investigate CR-1 in the context of expression in GBM. The study was performed using enzyme-linked immunosorbent assay (ELISA), Western blotting, polymerase chain reaction (PCR) and immunohistochemistry to analyze the blood and tissue from 28 GBM and 4 low-grade glioma patients. Within the patient cohort, we found high CR-1 protein levels in blood plasma to significantly correlate with a shorter overall survival. We identified CR-1 in different areas of GBM tissue, including perivascular tumor cells, and in endothelial cells. Collectively, our data suggest that CR-1 could be a prognostic biomarker for GBM with the potential of being a therapeutic target.

MiR-15a-16 represses Cripto and inhibits NSCLC cell progression

MicroRNAs (miRNAs) are small noncoding RNAs that have important roles in cancer. The altered expressions of miRNAs and their target genes are frequently detected in various tumors. In this study, downregulation of miR-15a-16 in nonsmall cell lung cancer (NSCLC) was found to be inversely correlated with Cripto. Results from the Luciferase reporter assay and Western blot analysis also confirmed that Cripto is a direct target of miR-15a-16. In addition, transfection of miR-15a-16 expression plasmid inhibited the invasion ability and promoted the apoptosis of NCI-H23 and NCI-H358 cells. Moreover, miR-15a-16 overexpression suppressed tumor growth in vivo. These findings clearly suggest that the downregulation of miR-15a-16 with Cripto amplification may be involved in the development of NSCLC.

Regulation of human Cripto-1 expression by nuclear receptors and DNA promoter methylation in human embryonal and breast cancer cells

Human Cripto-1 (CR-1) plays an important role in regulating embryonic development while also regulating various stages of tumor progression. However, mechanisms that regulate CR-1 expression during embryogenesis and tumorigenesis are still not well defined. In the present study, we investigated the effects of two nuclear receptors, liver receptor homolog (LRH)-1 and germ cell nuclear factor receptor (GCNF) and epigenetic modifications on CR-1 gene expression in NTERA-2 human embryonal carcinoma cells and in breast cancer cells. CR-1 expression in NTERA-2 cells was positively regulated by LRH-1 through direct binding to a DR0 element within the CR-1 promoter, while GCNF strongly suppressed CR-1 expression in these cells. In addition, the CR-1 promoter was unmethylated in NTERA-2 cells, while T47D, ZR75-1, and MCF7 breast cancer cells showed high levels of CR-1 promoter methylation and low CR-1 mRNA and protein expression. Treatment of breast cancer cells with a demethylating agent and histone deacetylase inhibitors reduced methylation of the CR-1 promoter and reactivated CR-1 mRNA and protein expression in these cells, promoting migration and invasion of breast cancer cells. Analysis of a breast cancer tissue array revealed that CR-1 was highly expressed in the majority of human breast tumors, suggesting that CR-1 expression in breast cancer cell lines might not be representative of in vivo expression. Collectively, these findings offer some insight into the transcriptional regulation of CR-1 gene expression and its critical role in the pathogenesis of human cancer.

Separation of tumor cells with dielectrophoresis-based microfluidic chip

The present work demonstrates the use of a dielectrophoretic lab-on-a-chip device in effectively separating different cancer cells of epithelial origin for application in circulating tumor cell (CTC) identification. This study uses dielectrophoresis (DEP) to distinguish and separate MCF-7 human breast cancer cells from HCT-116 colorectal cancer cells. The DEP responses for each cell type were measured against AC electrical frequency changes in solutions of varying conductivities. Increasing the conductivity of the suspension directly correlated with an increasing frequency value for the first cross-over (no DEP force) point in the DEP spectra. Differences in the cross-over frequency for each cell type were leveraged to determine a frequency at which the two types of cell could be separated through DEP forces. Under a particular medium conductivity, different types of cells could have different DEP behaviors in a very narrow AC frequency band, demonstrating a high specificity of DEP. Using a microfluidic DEP sorter with optically transparent electrodes, MCF-7 and HCT-116 cells were successfully separated from each other under a 3.2 MHz frequency in a 0.1X PBS solution. Further experiments were conducted to characterize the separation efficiency (enrichment factor) by changing experimental parameters (AC frequency, voltage, and flow rate). This work has shown the high specificity of the described DEP cell sorter for distinguishing cells with similar characteristics for potential diagnostic applications through CTC enrichment.

Cripto/GRP78 modulation of the TGF-β pathway in development and oncogenesis

Cripto is a small, GPI-anchored signaling protein that regulates cellular survival, proliferation, differentiation and migration during normal developmental processes and tumorigenesis. Cripto functions as an obligatory co-receptor for the TGF-β ligands Nodal, GDF1 and GDF3 but attenuates signaling of others such as activin-A, activin-B and TGF-β1. Soluble, secreted forms of Cripto also activate Src, ras/raf/MAPK and PI3K/Akt pathways via a mechanism that remains largely obscure. This review describes the biological roles and signaling mechanisms of Cripto, highlighting our identification of the 78 kDa glucose regulated protein (GRP78) as a cell surface receptor/co-factor required for Cripto signaling via both TGF-β and Src/MAPK/PI3K pathways. We discuss emerging evidence indicating that Cripto/GRP78 signaling regulates normal somatic stem cells and their tumorigenic counterparts.

Potential for the embryonic morphogen Nodal as a prognostic and predictive biomarker in breast cancer

Introduction

The re-emergence of the tumour growth factor-beta (TGF-beta)-related embryonic morphogen Nodal has recently been reported in several different human cancers. In this study, we examined the expression of Nodal in a series of benign and malignant human breast tissues to determine the clinical significance of this expression and whether Nodal could represent a potential therapeutic target in breast cancer.

Methods

Tissue sections from 431 therapeutically naive patients diagnosed with benign or malignant breast disease were stained for Nodal by immunohistochemistry and analysed in a blinded manner. The degree of Nodal staining was subsequently correlated with available clinical data, such as diagnoses and disease stage. These tissue findings were further explored in breast cancer cell lines MDA-MB-231 and MDA-MB-468 treated with a Nodal blocking antibody to determine biological effects for target validation.

Results

A variable degree of Nodal staining was detected in all samples. The intensity of Nodal staining was significantly greater in undifferentiated, advanced stage, invasive breast cancer compared with benign breast disease or early stage breast cancer. Treatment of human breast cancer cells in vitro with Nodal blocking antibody significantly reduced proliferation and colony-forming ability in soft agar, concomitant with increased apoptosis.

Conclusions

These data suggest a potential role for Nodal as a biomarker for disease progression and a promising target for anti-Nodal therapy in breast cancer.

Role of Cripto-1 during epithelial-to-mesenchymal transition in development and cancer

Epithelial-to-mesenchymal transition (EMT) is a critical multistep process that converts epithelial cells to more motile and invasive mesenchymal cells, contributing to body patterning and morphogenesis during embryonic development. In addition, both epithelial plasticity and increased motility and invasiveness are essential for the branching morphogenesis that occurs during development of the mammary gland and during tumor formation, allowing cancer cells to escape from the primary tumor. Cripto-1, a member of the epidermal growth factor-Cripto-1/FRL-1/Cryptic (EGF/CFC) gene family, together with the transforming growth factor (TGF)-β family ligand Nodal, regulates both cell movement and EMT during embryonic development. During postnatal development, Cripto-1 regulates the branching morphogenesis of the mouse mammary gland and enhances both the invasive and migratory properties of mammary epithelial cells in vitro. Furthermore, transgenic mouse models have shown that Cripto-1 promotes the formation of mammary tumors that display properties of EMT, including the down-regulation of the cell surface adherens junctional protein E-cadherin and the up-regulation of mesenchymal markers, such as vimentin, N-cadherin, and Snail. Interestingly, Cripto-1 is enriched in a subpopulation of embryonal, melanoma, prostate, and pancreatic cancer cells that possess stem-like characteristics. Therefore, Cripto-1 may play a role during developmental EMT, and it may also be involved in the reprogramming of differentiated tumor cells into cancer stem cells through the induction of an EMT program.

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.