Cripto as a target for cancer immunotherapy

Cripto-1 as a Potential Target of Cancer Stem Cells for Immunotherapy

Simple Summary

Cancer immunotherapy is gaining attention as a potential fourth treatment following surgery, chemotherapy, and radiation therapy. Cancer stem cells have recently been recognized and validated as a key target for cancer treatment. Cripto-1, which is a GPI-anchored membrane-bound protein that functions as a co-receptor of Nodal, is a marker of cancer stem cells. Since Nodal is a member of the TGF-β family, which performs an important role in stem cells and cancer stem cells, the inhibition of Cripto-1 could be a strategy by which to block Nodal signaling and thereby suppress cancer stem cells. We propose that Cripto-1 may be a novel target for cancer immunotherapy.

Abstract

The immune system has been found to be suppressed in cancer patients. Cancer cells are extremely resistant to chemotherapeutic drugs, conventional immunotherapy, or cancer antigen vaccine therapy. Cancer immunotherapy, which is mainly based on immune checkpoint inhibitors, such as those for PD-1, PD-L1, and CTLA4, is an effective treatment method. However, no immunotherapeutic target has been found that retains validity in the face of tumor diversity. The transforming growth factor (TGF)-β cytokine family possesses broad biological activity and is involved in the induction and/or transdifferentiation of helper T cells, which are important in immunotherapy. Nodal is a member of the TGF-β family playing important roles in tissue stem cells and cancer stem cells (CSCs), interacting with the co-receptor Cripto-1, as well as with Activin type IB (Alk4) and Activin typeIIreceptors, and maintaining stemness and Notch and Wnt/β-catenin signaling in CSCs. In recent years, it has been reported that Cripto-1 could be a potential therapeutic target in CSCs. Here, we review the accumulated literature on the molecular mechanisms by which Cripto-1 functions in CSCs and discuss the potential of Cripto-1 as an immunotherapeutic target in CSCs.

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.

Surface markers of human embryonic stem cells: a meta analysis of membrane proteomics reports

INTRODUCTION

Human embryonic stem cells (hESCs) have unique biological features and attributes that make them attractive in various areas of biomedical research. With heightened applications, there is an ever increasing need for advancement of proteome analysis. Membrane proteins are one of the most important subset of hESC proteins as they can be used as surface markers. Areas covered: This review discusses commonly used surface markers of hESCs, and provides in-depth analysis of available hESC membrane proteome reports and the existence of these markers in many other cell types, especially cancer cells. Appreciating, existing ambiguity in the definition of a membrane protein, we have attempted a meta analysis of the published membrane protein reports of hESCs by using a combination of protein databases and prediction tools to find the most confident plasma membrane proteins in hESCs. Furthermore, responsiveness of plasma membrane proteins to differentiation has been discussed based on available transcriptome profiling data bank. Expert commentary: Combined transcriptome and membrane proteome analysis highlighted additional proteins that may eventually find utility as new cell surface markers.

MUC1 cytoplasmic tail: a potential therapeutic target for ovarian carcinoma

Ovarian cancer is often a lethal disease, since the occult progression of the tumor within the peritoneal cavity results in late diagnosis and treatment failure. The identification of molecular events specific to metastasis is critical for the development of effective therapies. MUC1 is aberrantly overexpressed by most ovarian cancer and regarded as a molecular target for ovarian cancer. This review focuses on the latest advances regarding a signaling region in the MUC1 C-terminal subunit-mediated c-Src signaling pathways in malignant transformation, invasion and metastasis. Disruption of MUC1-C-terminal subunit-associated c-Src signaling by targeting the specific sites might represent a novel immunotherapeutic approach for the treatment of ovarian cancer.

Targeting the embryonic gene Cripto-1 in cancer and beyond

IMPORTANCE OF THE FIELD

Emerging evidence has clearly implicated an inappropriate activation of embryonic regulatory genes during cell transformation in adult tissues. An example of such a case is the embryonic gene Cripto-1. Cripto-1 is critical for embryonic development and is considered a marker of undifferentiated embryonic stem cells. Critpo-1 is expressed at low levels in adult tissues, but is re-expressed at a high frequency in a number of different types of human carcinomas, therefore, representing an attractive therapeutic target in cancer.

AREA COVERED IN THIS REVIEW

This review surveys different approaches that have been used to target Cripto-1 in cancer as reflected by the relevant patent literature as well as peer-reviewed publications. Potential involvement and targeting of Cripto-1 in neurodegenerative and degenerative muscle diseases are also discussed.

WHAT THE READER WILL GAIN

The reader will gain an overview of different mAbs, vaccines or oligonucleotides antisense targeting Cripto-1. A humanized anti-Cripto-1 antibody is currently being tested in a Phase I clinical trial in cancer patients.

TAKE HOME MESSAGE

Targeting Cripto-1 in human tumors has the potential to eliminate not only differentiated cancer cells but also destroy an undifferentiated subpopulation of cancer cells with stem-like characteristics that support tumor initiation and self-renewal.

Novel therapies against aggressive and recurrent epithelial cancers by molecular targeting tumor- and metastasis-initiating cells and their progenies

A growing body of experimental evidence has revealed that the highly tumorigenic cancer stem/progenitor cells endowed with stem cell-like properties might be responsible for initiation and progression of numerous aggressive epithelial cancers into locally invasive, metastatic and incurable disease states. The malignant transformation of tissue-resident adult stem/progenitor cells or their progenies into tumorigenic and migrating cancer stem/progenitor cells and their resistance to current cancer therapies have been associated with their high expression levels of specific oncogenic products and drug resistance-associated molecules. In this regard, we describe the tumorigenic cascades that are frequently activated in cancer stem/progenitor cells versus their differentiated progenies during the early and late stages of the epithelial cancer progression. The emphasis is on the growth factor signaling pathways involved in the malignant behavior of prostate and pancreatic cancer stem/progenitor cells and their progenies. Of clinical interest, the potential molecular therapeutic targets to eradicate the tumor- and metastasis-initiating cells and their progenies and develop new effective combination therapies against locally advanced and metastatic epithelial cancers are also described.

Human Cripto-1 as a target for a cancer vaccine: WO2008040759

Human Cripto-1 is a cell membrane protein that has been shown to be overexpressed in different types of human tumors. Because Cripto-1 is expressed at low levels in normal tissues, it represents a promising candidate for therapeutic intervention in cancer. The present patent describes a novel approach to target Cripto-1 in cancer using a vaccine. Immunization with Cripto-1 modified by addition of a foreign peptide to overcome T-cell tolerance for self-proteins has the potential to generate an antibody-based immune response that ultimately will block Cripto-1 activity in cancer cells. Although targeting Cripto-1 with a vaccine in cancer patients is promising, several experimental and clinical studies need to be done to validate this approach.

Functions of tumorigenic and migrating cancer progenitor cells in cancer progression and metastasis and their therapeutic implications

The in vitro and in vivo characterization of adult stem cells has allowed researchers to identify certain specific functional features to each tissue-specific stem cell. Moreover, recent studies revealed that their malignant counterparts, the cancer progenitor cells with stem cell-like properties, may assume a crucial role for the initiation and progression of locally invasive cancers into disseminated and incurable disease states. Therefore, a new direction in cancer research appears necessary in considering the critical functions of cancer progenitor cells. In this review, we discuss recent concepts on the critical roles of tumorigenic and migrating cancer progenitor cells in carcinogenesis. Particularly, we describe the tumorigenic cascades that are frequently activated through the interplay of diverse hormones, growth factors, cytokines and integrins in cancer progenitor cells versus their further differentiated progeny. The emphasis is on the oncogenic signaling pathways activated during the localized cancer progression and micrometastatic events involved in tumor formation at distant sites such as bone marrow. Of therapeutic interest, important information for the selective molecular targeting of cancer progenitor cells, which must now be considered in developing new effective diagnostic and prognostic methods and curative treatments against the most locally advanced and metastatic cancers, is also described.

Interplay of distinct growth factors during epithelial mesenchymal transition of cancer progenitor cells and molecular targeting as novel cancer therapies

In this review, we describe the critical functions assumed by the interplay of epidermal growth factor, hedgehog, Wnt/beta-catenin, tumor growth factor-beta and integrin signaling cascades in tumorigenic and migrating cancer progenitor cells and activated stromal cells during carcinogenesis. These growth factors provide an important role for the sustained growth and survival of tumorigenic cancer progenitor cells and their progeny by up-regulating numerous mitotic and antiapoptotic signaling cascades. Furthermore, these potent morphogens may cooperate for inducing the molecular events associated with the epithelial-mesenchymal program in cancer cells including the alterations in epithelial cell shape and motility through the dissociation of intercellular adherens junctions. Of therapeutic interest, new strategies for the development of more effective clinical treatments against the locally aggressive and invasive cancers based on the molecular targeting of deregulated signaling elements in tumorigenic and migrating cancer cells and their local microenvironment are also described.

Anti-Cripto Mab inhibit tumour growth and overcome MDR in a human leukaemia MDR cell line by inhibition of Akt and activation of JNK/SAPK and bad death pathways

Doxorubicin (DOX) selection of CCRF-CEM leukaemia cell line resulted in multidrug resistance (MDR) CEM/A7R cell line, which overexpresses MDR, 1 coded P-glycoprotein (Pgp). Here, we report for the first time that oncoprotein Cripto, a founding member of epidermal growth factor-Cripto-FRL, 1-Criptic family is overexpressed in the CEM/A7R cells, and anti-Cripto monoclonal antibodies (Mab) inhibited CEM/A7R cell growth both in vitro and in an established xenograft tumour in severe combined immunodeficiency mice. Cripto Mab synergistically enhanced sensitivity of the MDR cells to Pgp substrates epirubicin (EPI), daunorubicin (DAU) and non-Pgp substrates nucleoside analogue cytosine arabinoside (AraC). In particular, the combination of anti-Cripto Mab at less than 50% of inhibition concentrations with noncytotoxic concentrations of EPI or DAU inhibited more than 90% of CEM/A7R cell growth. Cripto Mab slightly inhibited Pgp expression, and had little effect on Pgp function, indicating that a mechanism independent of Pgp was involved in overcoming MDR. We demonstrated that anti-Cripto Mab-induced CEM/A7R cell apoptosis, which was associated with an enhanced activity of the c-Jun N-terminal kinase/stress-activated protein kinase and inhibition of Akt phosphorylation, resulting in an activation of mitochondrial apoptosis pathway as evidenced by dephosphorylation of Bad at Ser136, Bcl-2 at Ser70 and a cleaved caspase-9.

Cripto-1 expression in uveal melanoma: an immunohistochemical study

Human Cripto, the founder member of the epidermal growth factor-Cripto-FRL1-Cryptic (EGF-CFC) family, plays an important role during early embryonic development and in particular in carcinogenesis and the development of cancer metastases. Cripto-1 is over-expressed in most cancers, but is absent or only weakly expressed in normal cells. For this reason, Cripto-1 could be of potential value in the targeted treatment. There is no information on the expression of Cripto-1 in human uveal melanoma. Cripto-1 reactivity was evaluated by immunohistochemistry on 36 archival uveal melanomas using the polyclonal antibody to Cripto-1. The tumors were divided in to 2 groups. There were 18 uveal melanomas with no intrascleral or extrascleral extension and 18 uveal melanomas with intrascleral/extrascleral extension/liver metastasis. Cripto-1 reactivity was correlated with tumor aggressiveness and cell type. Furthermore, we studied the immunolocalization of Cripto-1 in 4 uveal melanoma cell lines OCM-1, OCM-8, and 92-1, and OMM-1 and in 2 primary uveal melanocyte cultures. Cripto-1 was expressed in both the non-invasive and aggressive uveal melanomas. Cripto-1 was positive in the 4 uveal melanoma cell lines and absent in the primary uveal melanocyte cultures. Retinal tissue did not express Cripto-1. The results suggest that Cripto-1 is expressed in uveal melanoma, negative in the non-neoplastic ocular tissue and point to its use as a target for therapy.