The expression of the embryonic gene Cripto-1 is regulated by OCT4 in human embryonal carcinoma NCCIT cells

Antibody-drug conjugates as a novel therapeutic modality to treat recurrent refractory germ cell tumors

This review provides a rationale for using the Food and Drug Administration (FDA)-approved antibody-drug conjugates (ADCs) for implementing as therapy in recurrent refractory germ cell tumors similar to their position in the treatment of other types of chemoresistant solid tumors. Germ cell tumors (GCTs) originate from germ cells; they most frequently develop in ovaries or in the testes, while being the most common type of malignancy in young men. GCTs are very sensitive to cisplatin-based chemotherapy, but therapeutic resistance occurs in a considerable number of cases, which is associated with disease recurrence and poor patient prognosis. ADCs are a novel type of targeted antitumor agents that combine tumor antigen-specific monoclonal antibodies with chemically linked chemotherapeutic drugs (payload) exerting a cytotoxic effect. Several FDA-approved ADCs use as targeting moieties the antigens that are also detected in the GCTs, offering a benefit of this type of targeted therapy even for patients with relapsed/refractory testicular GCTs (rrTGCT) unresponsive to standard chemotherapy.

Luteolin Inhibits Breast Cancer Stemness and Enhances Chemosensitivity through the Nrf2-Mediated Pathway

Cancer stem cells (CSCs) are subpopulations of tumor masses with unique abilities in self-renewal, stemness maintenance, drug resistance, and the promotion of cancer recurrence. Recent studies have suggested that breast CSCs play essential roles in chemoresistance. Therefore, new agents that selectively target such cells are urgently required. Reactive oxygen species (ROS)-producing enzymes are the reason for an elevated tumor oxidant status. The nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcriptional factor, which upon detecting cellular oxidative stress, binds to the promoter region of antioxidant genes. By triggering a cytoprotective response, Nrf2 maintains cellular redox status. Cripto-1 participates in the self-renewal of CSCs. Herein, luteolin, a flavonoid found in Taraxacum officinale extract, was determined to inhibit the expressions of stemness-related transcriptional factors, the ATP-binding cassette transporter G2 (ABCG2), CD44, aldehyde dehydrogenase 1 activity as well as the sphere formation properties of breast CSCs. Furthermore, luteolin suppressed the protein expressions of Nrf2, heme oxygenase 1 (HO-1), and Cripto-1 which have been determined to contribute critically to CSC features. The combination of luteolin and the chemotherapeutic drug, Taxol, resulted in enhanced cytotoxicity to breast cancer cells. These findings suggest that luteolin treatment significantly attenuated the hallmarks of breast cancer stemness by downregulating Nrf2-mediated expressions. Luteolin constitutes a potential agent for use in cancer stemness-targeted breast cancer treatments.

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.

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.

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.

Fli-1 promotes proliferation and upregulates NANOGP8 expression in T-lymphocyte leukemia cells

Friend leukemia integration 1 (Fli-1) is a member of the E26 transformation-specific (ETS) transcription factor family. Fli-1 regulates normal hematopoiesis and vasculogenesis, and its aberrant expression underlies virus-induced leukemias and various types of human cancers. NANOGP8, a retro-pseudogene of stem cell mediator NANOG, is expressed predominantly in cancer cells and plays a role in tumorigenesis. In this study, we demonstrate that Fli-1 expression enhances human acute T-cell leukemia Jurkat cell proliferation and that Fli-1 acts as a transcriptional activator of NANOGP8 expression in these cells. NANOGP8 and Fli-1 are highly expressed in Jurkat cells, whereas NANOG was undetectable at both the RNA and protein levels. Moreover, the expression of endogenous NANOGP8 was significantly influenced by gain of function and loss of function of Fli-1. Promoter-reporter assays showed that NANOGP8 transcription was significantly upregulated by dose-dependent Fli-1 overexpression. A series of deletion mutagenesis of NANOGP8 promoter sequence revealed that NANOGP8 promoter activity was tightly regulated and found the minimal promoter region sufficient to activate NANOGP8 transcription mediated by Fli-1. Moreover, site-directed mutagenesis of the putative binding site abolished both NANOGP8 full-length and minimal promoter activities. Binding assays revealed that Fli-1 directly interacts with the potent binding site in NANOG promoter region. Taken together, our data demonstrate that Fli-1 is a novel upstream transcriptional activator of NANOGP8 and provide the molecular details of Fli-1-mediated NANOGP8 gene expression. Ultimately, these findings may contribute to understanding the expanded regulatory mechanisms of oncogenic NANOGP8 and ETS family transcription factors in leukemogenesis.

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.

Identification of myosin II as a cripto binding protein and regulator of cripto function in stem cells and tissue regeneration

Cripto regulates stem cell function in normal and disease contexts via TGFbeta/activin/nodal, PI3K/Akt, MAPK and Wnt signaling. Still, the molecular mechanisms that govern these pleiotropic functions of Cripto remain poorly understood. We performed an unbiased screen for novel Cripto binding proteins using proteomics-based methods, and identified novel proteins including members of myosin II complexes, the actin cytoskeleton, the cellular stress response, and extracellular exosomes. We report that myosin II, and upstream ROCK1/2 activities are required for localization of Cripto to cytoplasm/membrane domains and its subsequent release into the conditioned media fraction of cultured cells. Functionally, we demonstrate that soluble Cripto (one-eyed pinhead in zebrafish) promotes proliferation in mesenchymal stem cells (MSCs) and stem cell-mediated wound healing in the zebrafish caudal fin model of regeneration. Notably, we demonstrate that both Cripto and myosin II inhibitors attenuated regeneration to a similar degree and in a non-additive manner. Taken together, our data present a novel role for myosin II function in regulating subcellular Cripto localization and function in stem cells and an important regulatory mechanism of tissue regeneration. Importantly, these insights may further the development of context-dependent Cripto agonists and antagonists for therapeutic benefit.

Administration of Cripto in GRP78 overexpressed human MSCs enhances stem cell viability and angiogenesis during human MSC transplantation therapy

OBJECTIVES

The purpose of this study was to explore the effectiveness of concurrent GRP78 overexpression combined with Cripto on hMSC proliferation and migration both in vitro and in vivo. Specifically, we explored whether the treatment enhances effectiveness of hMSC transplantation in ischaemic tissue.

MATERIALS AND METHODS

Human MSCs obtained from human adipose tissue were cultured in α-minimum essential medium (Hyclone, Logan, UT, USA) supplemented with 10% (v/v) foetal bovine serum (Hyclone), 100 U mL^-1 penicillin and 100 μg mL^-1 streptomycin. Murine hindlimb ischaemic model was generated with 8-week-old male nude BALB/c mice (Biogenomics, Seoul, Korea) maintained under a 12-h light/dark cycle following the established protocol with minor modification. Cellular injection was performed no later than 3 hour after surgery. Lipofectamine transfection, single-cell cultivation assay, transwell assay, scratch wound-healing migration assay, immunohistochemistry and western blotting assays were performed.

RESULTS

Overexpression of GRP78 along with Cripto enhanced hMSC proliferation, migration and invasion. It increased interaction of surface GRP78 receptor with Cripto via JAK2/STAT3 pathway. We confirmed our proposed mechanism by showing that treatment with GRP78 antibody blocks the enhancement in vitro. In vivo, we observed that Cripto induced by the hypoxic environment in hindlimb ischaemic model interacts with the overexpressed GRP78 and increases hMSC proliferation, migration and invasion potentials as well as angiogenesis around transplanted ischaemic site via cytokine secretions.

CONCLUSIONS

These results demonstrate supporting evidences that GRP78-Cripto combination technique offers novel strategy to enhance MSC proliferation, migration and invasion potentials as well as angiogenesis around ischaemic site, ultimately facilitating MSC-based transplantation therapy in ischaemic conditions.