MUC1* mediates the growth of human pluripotent stem cells

Advances in MUC1 resistance to chemotherapy in pancreatic cancer

The incidence of pancreatic cancer (PC), a highly fatal malignancy, is increasing every year. Chemotherapy is an important treatment for it in addition to surgery, yet most patients become resistant to chemotherapeutic agents within a few weeks of treatment initiation.​ MUC1 is a highly glycosylated transmembrane protein, and studies have shown that aberrantly glycosylated overexpression of MUC1 is involved in regulating the biology of chemoresistance in cancer cells. This article summarizes the mechanism of MUC1 in PC chemoresistance and reviews MUC1-based targeted therapies.

Comparison of mucin-1 in human breast cancer and canine mammary gland tumor: a review study

Mucin-1 (MUC-1) is a transmembrane glycoprotein, which bears many similarities between dogs and humans. Since the existence of animal models is essential to understand the significant factors involved in breast cancer mechanisms, canine mammary tumors (CMTs) could be used as a spontaneously occurring tumor model for human studies. Accordingly, this review assessed the comparison of canine and human MUC-1 based on their diagnostic and therapeutic aspects and showed how comparative oncology approaches could provide insights into translating pre-clinical trials from human to veterinary oncology and vice versa which could benefit both humans and dogs.

MUC1-C Contributes to the Maintenance of Human Embryonic Stem Cells and Promotes Somatic Cell Reprogramming

Mucin 1 (MUC1) is a transmembrane glycoprotein overexpressed in several cancer cells in which it regulates cell surface properties, tumor invasion, and cell death. Recently, we reported that MUC1-C, the C-terminal subunit of MUC1, is involved in the growth of mouse embryonic stem (ES) cells. However, the functional significance of MUC1-C in human ES cells remains unclear. In this study, we investigated the expression and function of MUC1-C in human ES cells. Based on reverse transcription-polymerase chain reaction, western blotting, and confocal microscopy following immunostaining, undifferentiated human ES cells expressed MUC1-C and the expression level decreased during differentiation. Inhibition of MUC1-C, by the peptide inhibitor GO201 that targets the cytoplasmic domain of MUC1-C (MUC1-CD), reduced cell proliferation and OCT4 protein expression, and promoted cell death. Moreover, the inhibition of MUC1-C increased the intracellular reactive oxygen species (ROS) levels and downregulated expression of glycolysis-related enzymes. These findings indicate that expression and function of MUC1-C are required for stem cell properties involved in cell proliferation, maintenance of pluripotency and optimal ROS levels, and a high glycolytic flux in human ES cells. In addition, forced overexpression of MUC1-CD increased the efficiency of reprogramming from fibroblast cells to induced pluripotent stem cells, suggesting that MUC1-C expression can contribute to the reprogramming process.

MUC1: Structure, Function, and Clinic Application in Epithelial Cancers

The transmembrane glycoprotein mucin 1 (MUC1) is a mucin family member that has different functions in normal and cancer cells. Owing to its structural and biochemical properties, MUC1 can act as a lubricant, moisturizer, and physical barrier in normal cells. However, in cancer cells, MUC1 often undergoes aberrant glycosylation and overexpression. It is involved in cancer invasion, metastasis, angiogenesis, and apoptosis by virtue of its participation in intracellular signaling processes and the regulation of related biomolecules. This review introduces the biological structure and different roles of MUC1 in normal and cancer cells and the regulatory mechanisms governing these roles. It also evaluates current research progress and the clinical applications of MUC1 in cancer therapy based on its characteristics.

MUC1-Targeted Radiopharmaceuticals in Cancer Imaging and Therapy

Mucin 1 (MUC1) is a large, transmembrane mucin glycoprotein overexpressed in most adenocarcinomas and plays an important role in tumor progression. Regarding its cellular distribution, biochemical features, and function, tumor-related MUC1 varies from the MUC1 expressed in normal cells. Therefore, targeting MUC1 for cancer immunotherapy and imaging can exploit the difference between cancerous and normal cells. Radiopharmaceuticals have a potential use as carriers for the delivery of radionuclides to tumors for a diagnostic imaging and radiotherapy. Several radiolabeled targeting molecules like peptides, antibodies, and aptamers have been efficiently demonstrated in detecting and treating cancer by targeting MUC1. This review provides a brief overview of the current status of developments and applications of MUC1-targeted radiopharmaceuticals in cancer imaging and therapy.

The Breast Cancer Stem Cells Traits and Drug Resistance

Drug resistance is a major challenge in breast cancer (BC) treatment at present. Accumulating studies indicate that breast cancer stem cells (BCSCs) are responsible for the BC drugs resistance, causing relapse and metastasis in BC patients. Thus, BCSCs elimination could reverse drug resistance and improve drug efficacy to benefit BC patients. Consequently, mastering the knowledge on the proliferation, resistance mechanisms, and separation of BCSCs in BC therapy is extremely helpful for BCSCs-targeted therapeutic strategies. Herein, we summarize the principal BCSCs surface markers and signaling pathways, and list the BCSCs-related drug resistance mechanisms in chemotherapy (CT), endocrine therapy (ET), and targeted therapy (TT), and display therapeutic strategies for targeting BCSCs to reverse drug resistance in BC. Even more importantly, more attention should be paid to studies on BCSC-targeted strategies to overcome the drug resistant dilemma of clinical therapies in the future.

Inhibition of MUC1-C Increases ROS and Cell Death in Mouse Embryonic Stem Cells

Background and Objectives

Embryonic stem (ES) cells have the capacity to self-renew and generate all types of cells. MUC1-C, a cytoplasmic subunit of MUC1, is overexpressed in various carcinomas and mediates signaling pathways to regulate intracellular metabolic processes and gene expression involved in the maintenance of cancer cells. However, the functional role of MUC1-C in ES cells is not well understood. In this study, we investigated the role of MUC1-C on growth, survival, and differentiation of mouse ES (mES) cells.

Methods and Results

Undifferentiated mES cells expressed the MUC1-C protein and the expression level was decreased during differentiation. Inhibition of MUC1-C, by the specific inhibitor GO201, reduced proliferation of mES cells. However, there was no prominent effect on pluripotent markers such as Oct4 expression and STAT3 signaling, and MUC1-C inhibition did not induce differentiation. Inhibition of MUC1-C increased the G1 phase population, decreased the S phase population, and increased cell death. Furthermore, inhibition of MUC1-C induced disruption of the ROS balance in mES cells.

Conclusions

These results suggest that MUC1-C is involved in the growth and survival of mES cells.

The primitive growth factor NME7AB induces mitochondrially active naïve-like pluripotent stem cells

Naïve pluripotent stem cells (PSCs) display a distinctive phenotype when compared to their "primed" counterparts, including, but not limited to, increased potency to differentiate and more robust mitochondrial respiration. The cultivation and maintenance of naïve PSCs have been notoriously challenging, requiring the use of complex cytokine cocktails. NME7AB is a newly discovered embryonic stem cell growth factor that is expressed exclusively in the first few days of human blastocyst development. It has been previously reported that growing primed induced PSCs (iPSCs) in bFGF-depleted medium with NME7AB as the only added growth factor facilitates the regression of these cells to their naïve state. Here, we confirm this regression by demonstrating the reactivation of mitochondrial function in the induced naïve-like PSCs and increased ATP production in these cells, as compared to that in primed iPSCs.

Mucins: the Old, the New and the Promising Factors in Hepatobiliary Carcinogenesis

Mucins are large O-glycoproteins with high carbohydrate content and marked diversity in both the apoprotein and the oligosaccharide moieties. All three mucin types, trans-membrane (e.g., MUC1, MUC4, MUC16), secreted (gel-forming) (e.g., MUC2, MUC5AC, MUC6) and soluble (non-gel-forming) (e.g., MUC7, MUC8, MUC9, MUC20), are critical in maintaining cellular functions, particularly those of epithelial surfaces. Their aberrant expression and/or altered subcellular localization is a factor of tumour growth and apoptosis induced by oxidative stress and several anti-cancer agents. Abnormal expression of mucins was observed in human carcinomas that arise in various gastrointestinal organs. It was widely believed that hepatocellular carcinoma (HCC) does not produce mucins, whereas cholangiocarcinoma (CC) or combined HCC-CC may produce these glycoproteins. However, a growing number of reports shows that mucins can be produced by HCC cells that do not exhibit or are yet to undergo, morphological differentiation to biliary phenotypes. Evaluation of mucin expression levels in precursors and early lesions of CC, as well as other types of primary liver cancer (PLC), conducted in in vitro and in vivo models, allowed to discover the mechanisms of their action, as well as their participation in the most important signalling pathways of liver cystogenesis and carcinogenesis. Analysis of mucin expression in PLC has both basic research and clinical value. Mucins may act as oncogenes and tumour-promoting (e.g., MUC1, MUC13), and/or tumour-suppressing factors (e.g., MUC15). Given their role in promoting PLC progression, both classic (MUC1, MUC2, MUC4, MUC5AC, MUC6) and currently tested mucins (e.g., MUC13, MUC15, MUC16) have been proposed to be important diagnostic and prognostic markers. The purpose of this review was to summarize and update the role of classic and currently tested mucins in pathogenesis of PLC, with explaining the mechanisms of their action in HCC carcinogenesis. It also focuses on determination of the diagnostic and prognostic role of these glycoproteins in PLC, especially focusing on HCC, CC and other hepatic tumours with- and without biliary differentiation.

Glycosylation of Cancer Stem Cells: Function in Stemness, Tumorigenesis, and Metastasis

Aberrant glycosylation plays a critical role in tumor aggressiveness, progression, and metastasis. Emerging evidence associates cancer initiation and metastasis to the enrichment of cancer stem cells (CSCs). Several universal markers have been identified for CSCs characterization; however, a specific marker has not yet been identified for different cancer types. Specific glycosylation variation plays a major role in the progression and metastasis of different cancers. Interestingly, many of the CSC markers are glycoproteins and undergo differential glycosylation. Given the importance of CSCs and altered glycosylation in tumorigenesis, the present review will discuss current knowledge of altered glycosylation of CSCs and its application in cancer research.

The 'known-knowns', and 'known-unknowns' of extracellular Nm23-H1/NDPK proteins

Nucleoside diphosphate kinases (NDPKs/NDK/NME) are a multifunctional class of proteins conserved throughout evolution. Whilst many of the functions of NDPKs have been identified as intracellular, extracellular eukaryotic and prokaryotic NDPK proteins are also detected in multiple systems and have been implicated in both normal physiology and disease. This review provides an overview of where the field stands on our developing understanding of how NDPK proteins get out of cells, the physiological role of extracellular NDPKs, and how extracellular NDPKs may signal to cells. We will also discuss some of the unanswered questions, the 'known-unknowns' that particularly warrant further investigation.

Extracellular NME proteins: a player or a bystander?

The Nm23/NME gene family has been under intensive study since Nm23H1/NME1 was identified as the first metastasis suppressor. Inverse correlation between the expression levels of NME1/2 and prognosis has indeed been demonstrated in different tumor cohorts. Interestingly, the presence of NME proteins in the extracellular environment in normal and tumoral conditions has also been noted. In many reported cases, however, these extracellular NME proteins exhibit anti-differentiation or oncogenic functions, contradicting their canonical anti-metastatic action. This emerging field thus warrants further investigation. In this review, we summarize the current understanding of extracellular NME proteins. A role in promoting stem cell pluripotency and inducing development of central nervous system as well as a neuroprotective function of extracellular NME have been suggested. Moreover, a tumor-promoting function of extracellular NME also emerged at least in some tumor cohorts. In this complex scenario, the secretory mechanism through which NME proteins exit cells is far from being understood. Recently, some evidence obtained in the Drosophila and cancer cell line models points to the involvement of Dynamin in controlling the balance between intra- and extracellular levels of NME. Further analyses on extracellular NME will lead to a better understanding of its physiological function and in turn will allow understanding of how its deregulation contributes to carcinogenesis.

NDPKA is not just a metastasis suppressor - be aware of its metastasis-promoting role in neuroblastoma

NDPK-A, encoded by nm23-H1 (also known as NME1) was the first metastasis suppressor discovered. Much of the attention has been focused on the metastasis-suppressing role of NDPK-A in human tumors, including breast carcinoma and melanoma. However, compelling evidence points to a metastasis-promoting role of NDPK-A in certain tumors such as neuroblastoma and lymphoma. To balance attention on this contrariety of NDPK-A in different cancer types, this review addresses the metastasis-promoting role of NDPK-A in neuroblastoma. Neuroblastoma is an embryonic tumor, arising from neural crest cells that fail to differentiate into the sympathetic nervous system. We summarize and discuss nm23-H1 genetics and the prognosis of neuroblastoma, structural and functional changes associated with the S120G mutation of NDPK-A, as well as the evidence supporting the role of NDPK-A as a metastasis promoter. Also discussed are the NDPK-A relevant molecular determinants of neuroblastoma metastasis, and metastasis-relevant neural crest development. Because of NDPK-A's dichotomous role in tumor metastasis as both a suppressor and a promoter, tumor genome/exome profiles are necessary to identify the molecular drivers of metastasis in the NDPK-A network for developing tumor-specific therapies.

Anti-MUC1 aptamer: A potential opportunity for cancer treatment

Mucin 1 (MUC1) is a protein usually found on the apical surface of most normal secretory epithelial cells. However, in most adenocarcinomas, MUC1 is overexpressed, so that it not only appears over the entire cell surface, but is also shed as MUC1 fragments into the blood stream. These phenomena pinpoint MUC1 as a potential target for the diagnosis and treatment of cancer; consequently, interest has increased in MUC1 as a molecular target for overcoming cancer therapy challenges. MUC1 currently ranks second among 75 antigen candidates for cancer vaccines, and different antibodies or aptamers against MUC1 protein are proving useful for tracing cancer cells in the emerging field of targeted delivery. The unique properties of MUC1 aptamers as novel targeting agents, and the revolutionary role that MUC1 now plays in cancer therapy, are the focus of this review. Recent advancements in MUC1-targeted cancer therapy are also assessed.

Predicting and Overcoming Chemotherapeutic Resistance in Breast Cancer

Our understanding of breast cancer and its therapeutic approach has improved greatly due to the advancement of molecular biology in recent years. Clinically, breast cancers are characterized into three basic types based on their immunohistochemical properties. They are triple-negative breast cancer, estrogen receptor (ER) and progesterone receptor (PR)-positive-HR positive breast cancer, and human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Even though these subtypes have been characterized, assessment of a breast cancer's receptor status is still widely used to determine whether or not a targeted therapy could be applied. Moreover, drug resistance is common in all breast cancer types despite the different treatment modalities applied. The development of resistance to different therapeutics is not mutually exclusive. It seems that tumor could be resistant to multiple treatment strategies, such as being both chemoresistant and monoclonal antibody resistant. However, the underlying mechanisms are complicated and need further investigation. In this chapter, we aim to provide a brief review of the different types of breast cancer and their respective treatment strategies. We also review the possible mechanisms of potential drug resistance associated with each treatment type. We believe that a better understanding of the drug resistance mechanisms can lead to a more effective and efficient therapeutic success.

Induced pluripotent stem cells as a cellular model for studying Down Syndrome

Down Syndrome (DS), or Trisomy 21 Syndrome, is one of the most common genetic diseases. It is a chromosomal abnormality caused by a duplication of chromosome 21. DS patients show the presence of a third copy (or a partial third copy) of chromosome 21 (trisomy), as result of meiotic errors. These patients suffer of many health problems, such as intellectual disability, congenital heart disease, duodenal stenosis, Alzheimer's disease, leukemia, immune system deficiencies, muscle hypotonia and motor disorders. About one in 1000 babies born each year are affected by DS. Alterations in the dosage of genes located on chromosome 21 (also called HSA21) are responsible for the DS phenotype. However, the molecular pathogenic mechanisms of DS triggering are still not understood; newest evidences suggest the involvement of epigenetic mechanisms. For obvious ethical reasons, studies performed on DS patients, as well as on human trisomic tissues are limited. Some authors have proposed mouse models of this syndrome. However, not all the features of the syndrome are represented. Stem cells are considered the future of molecular and regenerative medicine. Several types of stem cells could provide a valid approach to offer a potential treatment for some untreatable human diseases. Stem cells also represent a valid system to develop new cell-based drugs and/or a model to study molecular disease pathways. Among stem cell types, patient-derived induced pluripotent stem (iPS) cells offer some advantages for cell and tissue replacement, engineering and studying: self-renewal capacity, pluripotency and ease of accessibility to donor tissues. These cells can be reprogrammed into completely different cellular types. They are derived from adult somatic cells via reprogramming with ectopic expression of four transcription factors (Oct3/4, Sox2, c-Myc and Klf4; or, Oct3/4, Sox2, Nanog, and Lin28). By reprogramming cells from DS patients, it is possible to obtain new tissue with the same genetic background, offering a valuable tool for studying this genetic disease and to design customized patient-specific stem cell therapies.

Induced pluripotent stem cells as a cellular model for studying Down Syndrome

Down Syndrome (DS), or Trisomy 21 Syndrome, is one of the most common genetic diseases. It is a chromosomal abnormality caused by a duplication of chromosome 21. DS patients show the presence of a third copy (or a partial third copy) of chromosome 21 (trisomy), as result of meiotic errors. These patients suffer of many health problems, such as intellectual disability, congenital heart disease, duodenal stenosis, Alzheimer’s disease, leukemia, immune system deficiencies, muscle hypotonia and motor disorders. About one in 1000 babies born each year are affected by DS. Alterations in the dosage of genes located on chromosome 21 (also called HSA21) are responsible for the DS phenotype. However, the molecular pathogenic mechanisms of DS triggering are still not understood; newest evidences suggest the involvement of epigenetic mechanisms. For obvious ethical reasons, studies performed on DS patients, as well as on human trisomic tissues are limited. Some authors have proposed mouse models of this syndrome. However, not all the features of the syndrome are represented. Stem cells are considered the future of molecular and regenerative medicine. Several types of stem cells could provide a valid approach to offer a potential treatment for some untreatable human diseases. Stem cells also represent a valid system to develop new cell-based drugs and/or a model to study molecular disease pathways. Among stem cell types, patient-derived induced pluripotent stem (iPS) cells offer some advantages for cell and tissue replacement, engineering and studying: self-renewal capacity, pluripotency and ease of accessibility to donor tissues. These cells can be reprogrammed into completely different cellular types. They are derived from adult somatic cells via reprogramming with ectopic expression of four transcription factors (Oct3/4, Sox2, c-Myc and Klf4; or, Oct3/4, Sox2, Nanog, and Lin28). By reprogramming cells from DS patients, it is possible to obtain new tissue with the same genetic background, offering a valuable tool for studying this genetic disease and to design customized patient-specific stem cell therapies.

Glycans define the stemness of naïve and primed pluripotent stem cells

Cell surface glycans are tissue-specific and developmentally regulated. They function as essential modulators in cell-cell interactions, cell-extracellular matrix interactions, and ligand-receptor interactions, binding to various ligands, including Wnt, fibroblast growth factors, and bone morphogenetic proteins. Embryonic stem (ES) cells, originally derived from the inner cell mass of blastocysts, have the essential characteristics of pluripotency and self-renewal. Recently, it has been proposed that mouse and human conventional ES cells are present in different developmental stages, namely pre-implantation blastocyst and post-implantation blastocyst stages, also called the naïve state and the primed state, respectively. They therefore require different extrinsic signals for the maintenance of self-renewal and pluripotency, and also appear to require different surface glycans. Understanding of molecular mechanisms involving glycans in self-renewal and pluripotency of ES cells is increasingly important for potential clinical applications, as well as for basic research. This review focuses on the roles of glycans in the two different states of pluripotent stem cells, namely the naïve state and the primed state, and the transition between these two states.

Genetically engineered mucin mouse models for inflammation and cancer

Mucins are heavily O-glycosylated proteins primarily produced by glandular and ductal epithelial cells, either in membrane-tethered or secretory forms, for providing lubrication and protection from various exogenous and endogenous insults. However, recent studies have linked their aberrant overexpression with infection, inflammation, and cancer that underscores their importance in tissue homeostasis. In this review, we present current status of the existing mouse models that have been developed to gain insights into the functional role(s) of mucins under physiological and pathological conditions. Knockout mouse models for membrane-associated (Muc1 and Muc16) and secretory mucins (Muc2) have helped us to elucidate the role of mucins in providing effective and protective barrier functions against pathological threats, participation in disease progression, and improved our understanding of mucin interaction with biotic and abiotic environmental components. Emphasis is also given to available transgenic mouse models (MUC1 and MUC7), which has been exploited to understand the context-dependent regulation and therapeutic potential of human mucins during inflammation and cancer.

Reflections on MUC1 glycoprotein: the hidden potential of isoforms in carcinogenesis

Mucin 1 (MUC1) has been described as the renaissance molecule due to the large set of functions it displays in both normal and neoplastic cells. This membrane-tethered glycoprotein is overexpressed and aberrantly glycosylated in most epithelial cancers, being involved in several processes related with malignant phenotype acquisition. With a highly polymorphic structure, both in the polypeptide and glycan counterparts, MUC1 variability has been associated with susceptibility to several diseases, including cancer. Biochemical features and biological functions have been characterized upon the full-length MUC1 protein, remaining to clarify the real impact on cell dynamics of the plethora of MUC1 isoforms. This review aims to encompass a detailed characterization of MUC1 role in carcinogenesis, highlighting recent findings in cell differentiation and uncovering new evidences of MUC1 isoforms involvement in malignant phenotype.

Effect of MUC1/β-catenin interaction on the tumorigenic capacity of pancreatic CD133+ cells

Despite the fact that the biological function of cluster of differentiation (CD)133 remains unclear, this glycoprotein is currently used in the identification and isolation of tumor-initiating cells from certain malignant tumors, including pancreatic cancer. In the present study, the involvement of mucin 1 (MUC1) in the signaling pathways of a highly tumorigenic CD133+ cellular subpopulation sorted from the pancreatic cancer cell line HPAF-II was evaluated. The expression of MUC1-cytoplasmic domain (MUC1-CD) and oncogenic signaling transducers (epidermal growth factor receptor, protein kinase C delta, glycogen synthase kinase 3 beta and growth factor receptor-bound protein 2), as well as the association between MUC1 and β-catenin, were characterized in HPAF-II CD133+ and CD133low cell subpopulations and in tumor xenografts generated from these cells. Compared with HPAF CD133^low cells, HPAF-II CD133+ cancer cells exhibited increased tumorigenic potential in immunocompromised mice, which was associated with overexpression of MUC1 and with the accordingly altered expression profile of MUC1-associated signaling partners. Additionally, MUC1-CD/β-catenin interactions were increased both in the HPAF-II CD133+ cell subpopulation and derived tumor xenografts compared with HPAF CD133^low cells. These results suggest that, in comparison with HPAF CD133^low cells, CD133+ cells exhibit higher expression of MUC1, which contributes to their tumorigenic phenotype through increased interaction between MUC1-CD and β-catenin, which in turn modulates oncogenic signaling cascades.

A Primitive Growth Factor, NME7AB , Is Sufficient to Induce Stable Naïve State Human Pluripotency; Reprogramming in This Novel Growth Factor Confers Superior Differentiation

Scientists have generated human stem cells that in some respects mimic mouse naïve cells, but their dependence on the addition of several extrinsic agents, and their propensity to develop abnormal karyotype calls into question their resemblance to a naturally occurring "naïve" state in humans. Here, we report that a recombinant, truncated human NME7, referred to as NME7AB here, induces a stable naïve-like state in human embryonic stem cells and induced pluripotent stem cells without the use of inhibitors, transgenes, leukemia inhibitory factor (LIF), fibroblast growth factor 2 (FGF2), feeder cells, or their conditioned media. Evidence of a naïve state includes reactivation of the second X chromosome in female source cells, increased expression of naïve markers and decreased expression of primed state markers, ability to be clonally expanded and increased differentiation potential. RNA-seq analysis shows vast differences between the parent FGF2 grown, primed state cells, and NME7AB converted cells, but similarities to altered gene expression patterns reported by others generating naïve-like stem cells via the use of biochemical inhibitors. Experiments presented here, in combination with our previous work, suggest a mechanistic model of how human stem cells regulate self-replication: an early naïve state driven by NME7, which cannot itself limit self-replication and a later naïve state regulated by NME1, which limits self-replication when its multimerization state shifts from the active dimer to the inactive hexamer.

MUC1 (CD227): a multi-tasked molecule

Mucin 1 (MUC1 [CD227]) is a high-molecular weight (>400 kDa), type I membrane-tethered glycoprotein that is expressed on epithelial cells and extends far above the glycocalyx. MUC1 is overexpressed and aberrantly glycosylated in adenocarcinomas and in hematological malignancies. As a result, MUC1 has been a target for tumor immunotherapeutic studies in mice and in humans. MUC1 has been shown to have anti-adhesive and immunosuppressive properties, protects against infections, and is involved in the oncogenic process as well as in cell signaling. In addition, MUC1 plays a key role in the reproductive tract, in the immune system (affecting dendritic cells, monocytes, T cells, and B cells), and in chronic inflammatory diseases. Evidence for all of these roles for MUC1 is discussed herein and demonstrates that MUC1 is truly a multitasked molecule.

Staurosporine Induced Apoptosis May Activate Cancer Stem-Like Cells (CD44(+)/CD24(-)) in MCF-7 by Upregulating Mucin1 and EpCAM

Malignant tumors recur after chemotherapy. A small population of cancer stem-like cells within tumors is now generally considered the prime source of the recurrence. To better understand how cancer stem-like cells induce relapse after fractionated chemotherapy, we examined changes in the CD44(+)/CD24(-) cancer stem-like cells population and behavior using the breast cancer cell line MCF-7. Our results show that apart from an increase in the CD44(+)/CD24(-) population, proliferation and clone formation, but not migration, were enhanced after recovery from apoptosis induced by two pulses of staurosporine (STS). The distribution of cells in the cell cycle differed between acutely induced apoptosis and fractionated chemotherapy. Sorted CD44(+)/CD24(-) stem-like cells from MCF-7 cells recovered from STS treatment possessed greater proliferation abilities. We also observed that mucin1 (MUC1) and Epithelial cell adhesion molecule (EpCAM) were up-regulated in abundance coincidently with proliferation and clone formation enhancement. Our findings suggest that fractionated chemotherapy induced apoptosis could stimulate cancer stem-like cell to behave with a stronger malignant property than cancer cells themselves and MUC1 and EpCAM are important factors involving in this process. By demonstrating changes in cancer stem cell during chemotherapy and identifying the crucial factors, we potentially can target them, to eradicate tumors and overcome cancer relapse.

Exposure of tumor-associated macrophages to apoptotic MCF-7 cells promotes breast cancer growth and metastasis

Tumor-associated macrophages (TAMs) have been found to be associated with the progression and metastasis of breast cancer. To clarify the mechanisms underlying the crosstalk between TAMs and cancer stem cells (CSCs) in breast cancer recurrence and metastasis, we used a co-culture model of macrophages and apoptotic human breast cancer cell line MCF-7 cells to investigate the effects of TAMs on MCF-7 in vitro and in vivo. Macrophages co-cultured with apoptotic MCF-7 had increased tumor growth and metastatic ability in a nude mouse transplantation assay. The macrophages exposed to apoptotic cells also induce an increase in the proportion of CD44⁺/CD24⁻ cancer stem-like cells, as well as their proliferative ability accompanied with an increase in mucin1 (MUC1) expression. During this process, macrophages secreted increased amounts of interleukin 6 (IL-6) leading to increased phosphorylation of signal transducers and activators of transcription 3 (STAT3), which likely explains the increased transcription of STAT3 target genes such as TGF-β1 and HIF-1α. Our results indicate that when cancer cells endure chemotherapy induced apoptosis, macrophages in their microenvironment can then activate cancer stem cells to promote cancer growth and metastasis by secreting IL-6, which activates STAT3 phosphorylation to regulate the transcription of its downstream target genes.

Regulatory functions of Nm23-H2 in tumorigenesis: insights from biochemical to clinical perspectives

Substantial effort has been directed at elucidating the functions of the products of the Nm23 tumor metastasis suppressor genes over the past two decades, with the ultimate goal of exploring their translational potentials in changing cancer patients' outcomes. Much attention has been focused on the better-known Nm23-H1, but despite having high sequence similarity, Nm23-H2 functions differently in many aspects. Besides acting as a metastasis suppressor, compelling data suggest that Nm23-H2 may modulate various tumor-associated biological events to enhance tumorigenesis in human solid tumors and hematological malignancies. Linkage to tumorigenesis may occur through the ability of Nm23-H2 to regulate transcription, cell proliferation, apoptosis, differentiation, and telomerase activity. In this review, we examine the linkages of Nm23-H2 to tumorigenesis in terms of its biochemical and structural properties and discuss its potential role in various tumor-associated events.

Adenoviral vectors for prodrug activation-based gene therapy for cancer

Cancer cell heterogeneity is a common feature - both between patients diagnosed with the same cancer and within an individual patient's tumor - and leads to widely different response rates to cancer therapies and the potential for the emergence of drug resistance. Diverse therapeutic approaches have been developed to combat the complexity of cancer, including individual treatment modalities designed to target tumor heterogeneity. This review discusses adenoviral vectors and how they can be modified to replicate in a cancer-specific manner and deliver therapeutic genes under multi-tiered regulation to target tumor heterogeneity, including heterogeneity associated with cancer stem cell-like subpopulations. Strategies that allow for combination of prodrug-activation gene therapy with a novel replication-conditional, heterogeneous tumor-targeting adenovirus are discussed, as are the benefits of using adenoviral vectors as tumor-targeting oncolytic vectors. While the anticancer activity of many adenoviral vectors has been well established in preclinical studies, only limited successes have been achieved in the clinic, indicating a need for further improvements in activity, specificity, tumor cell delivery and avoidance of immunogenicity.

MUC1 Is Expressed by Human Skin Fibroblasts and Plays a Role in Cell Adhesion and Migration

The mucin MUC1 is expressed by normal and cancerous epithelial cells and some nonepithelial cells in which it plays roles in regulating adhesion, migration, and cell signaling. In the present studies we found that MUC1 is expressed by normal human neonatal and adult skin fibroblasts. Fibroblasts are usually considered negative for MUC1 expression. Reverse-transcription polymerase chain reaction and Western blot analyses indicate the presence of full-length MUC1, and immunofluorescence and subcellular fractionation studies show that the protein is expressed on the plasma membrane. Immunohistochemical analyses confirmed the expression of MUC1 by fibroblasts in cryosections of normal human skin. Silencing MUC1 expression in fibroblasts using MUC1 shRNA increased the adhesion of cells to collagen and laminin. Transfection with MUC1 shRNA also increased fibroblast migration on collagen as measured in a wound-healing assay. The expression of α₂-integrin was increased in MUC1 shRNA-transfected fibroblasts in which it was localized to membrane ruffles, providing a possible explanation for the increased cell migration on collagen. These results extend the range of expression of MUC1 to skin fibroblasts and suggest a functional role for MUC1 in fibroblast adhesion and motility.

Mucin 1 gene (MUC1) and gastric-cancer susceptibility

Gastric cancer (GC) is one of the major malignant diseases worldwide, especially in Asia. It is classified into intestinal and diffuse types. While the intestinal-type GC (IGC) is almost certainly caused by Helicobacter pylori (HP) infection, its role in the diffuse-type GC (DGC) appears limited. Recently, genome-wide association studies (GWAS) on Japanese and Chinese populations identified chromosome 1q22 as a GC susceptibility locus which harbors mucin 1 gene (MUC1) encoding a cell membrane-bound mucin protein. MUC1 has been known as an oncogene with an anti-apoptotic function in cancer cells; however, in normal gastric mucosa, it is anticipated that the mucin 1 protein has a role in protecting gastric epithelial cells from a variety of external insults which cause inflammation and carcinogenesis. HP infection is the most definite insult leading to GC, and a protective function of mucin 1 protein has been suggested by studies on Muc1 knocked-out mice.

MUC1: a multifaceted oncoprotein with a key role in cancer progression

The transmembrane glycoprotein Mucin 1 (MUC1) is aberrantly glycosylated and overexpressed in a variety of epithelial cancers, and plays a crucial role in progression of the disease. Tumor-associated MUC1 differs from the MUC1 expressed in normal cells with regard to its biochemical features, cellular distribution, and function. In cancer cells, MUC1 participates in intracellular signal transduction pathways and regulates the expression of its target genes at both the transcriptional and post-transcriptional levels. This review highlights the structural and functional differences that exist between normal and tumor-associated MUC1. We also discuss the recent advances made in the use of MUC1 as a biomarker and therapeutic target for cancer.

Erythropoietin increases neuronal NDPKA expression, and NDPKA up-regulation as well as exogenous application protects cortical neurons from in vitro ischemia-related insults

Using proteomics, we identified nucleoside diphosphate kinase A (NDPKA; also known as NME/NM23 nucleoside diphosphate kinase 1: NME1) to be up-regulated in primary cortical neuronal cultures by erythropoietin (EPO) preconditioning. To investigate a neuroprotective role of NDPKA in neurons, we used a RNAi construct to knock-down and an adenoviral vector to overexpress the protein in cortical neuronal cultures prior to exposure to three ischemia-related injury models; excitotoxicity (L-glutamic acid), oxidative stress (hydrogen peroxide), and in vitro ischemia (oxygen-glucose deprivation). NDPKA down-regulation had no effect on neuronal viability following injury. By contrast, NDPKA up-regulation increased neuronal survival in all three-injury models. Similarly, treatment with NDPKA recombinant protein increased neuronal survival, but only against in vitro ischemia and excitotoxicity. These findings indicate that the NDPKA protein may confer a neuroprotective advantage following injury. Furthermore, as exogenous NDPKA protein was neuroprotective, it suggests that a cell surface receptor may be activated by NDPKA leading to a protective cell-signaling response. Taken together both NDPKAs intracellular and extracellular neuroprotective actions suggest that the protein is a legitimate therapeutic target for the design of drugs to limit neuronal death following stroke and other forms of brain injury.

Overview of cancer stem cells (CSCs) and mechanisms of their regulation: implications for cancer therapy

The identification of small subpopulations of cancer stem cells (CSCs) from blood mononuclear cells in human acute myeloid leukemia (AML) in 1997 was a landmark observation that recognized the potential role of CSCs in tumor aggressiveness. Two critical properties contribute to the functional role of CSCs in the establishment and recurrence of cancerous tumors: their capacity for self-renewal and their potential to differentiate into unlimited heterogeneous populations of cancer cells. These findings suggest that CSCs may represent novel therapeutic targets for the treatment and/or prevention of tumor progression, since they appear to be involved in cell migration, invasion, metastasis, and treatment resistance-all of which lead to poor clinical outcomes. The identification of CSC-specific markers, the isolation and characterization of CSCs from malignant tissues, and targeting strategies for the destruction of CSCs provide a novel opportunity for cancer research. This overview describes the potential implications of several common CSC markers in the identification of CSC subpopulations that are restricted to common malignant diseases, e.g., leukemia, and breast, prostate, pancreatic, and lung cancers. The role of microRNAs (miRNAs) in the regulation of CSC function is also discussed, as are several methods commonly used in CSC research. The potential role of the antidiabetic drug metformin- which has been shown to have effects on CSCs, and is known to function as an antitumor agent-is discussed as an example of this new class of chemotherapeutics.

Extracellular NM23 Signaling in Breast Cancer: Incommodus Verum

The notion that breast cancers can survive in an individual patient in a dormant state only to grow as metastatic disease in the future, is in our view incontrovertibly established. Convincing too is the evidence that surgery to remove the primary tumor often terminates dormancy resulting in accelerated relapses. Accepting that many deaths due to breast cancer might be averted were we to understand the cellular mechanisms underlying escape from dormancy, we have examined the extracellular signals produced by breast cancers derived from women with metastatic breast disease. In this perspective, we explore the role of extracellular nucleotide signaling that we have proposed constitutes a pathological axis from the transformed tumor cell to the endothelium in the service of intravasation, dissemination, extravasation and angiogenesis. A role for the dinucleotide kinase NM23/NDPK (nucleoside diphosphate kinase) secreted by breast tumor cells in the generation of signals that stimulate vascular leakiness, anti-thrombosis, endothelial migration and growth, constitutes a mechanistic basis for escape from latency and offers putative therapeutic targets for breast cancer management not previously appreciated.

The co-expression of functional gastric proteins in dynamic gastric diseases and its clinical significance

Background

Pepsinogen C (PGC) and mucin1 (MUC1) are important physiologically functional gastric proteins; Mucin2 (MUC2) is an “ectopic” functional protein in intestinal metaplasia of gastric mucosa. We analyzed the co-expression of the above-mentioned three proteins in dynamic gastric diseases {superficial gastritis (SG)-atrophic gastritis (AG)--gastric cancer (GC)} as well as different histological types of gastric cancer in order to find molecular phenotypes of gastric cancer and precancerous disease and further explore the potential co-function of PGC, MUC1 and MUC2 in the occurrence and development of gastric cancer.

Methods

The SG-AG-GC sequence was 57-57-70 cases in this case–control study, respectively. Different histological types of GC were 28 cases of highly and moderately differentiated aden ocarcinoma (HMDA)、30 of poorly differentiated adenocarcinoma (PDA) and 12 of mucinous adenocarcinoma (MA) or signet ring cell carcinoma (SRCC). PGC, MUC1 and MUC2 expression in situ were detected in all 184 cases using immunohistochemistry.

Results

Both PGC and MUC1 had a significantly decreased expression in GC than in SG and AG (P < 0.0001 and P < 0.01, respectively); While MUC2 had a significant increased expression in AG than in SG and GC (P < 0.0001). Seven phenotypes of PGC, MUC1 and MUC2 co-expression were found in which PGC+/MUC1+/MUC2- phenotype took 94.7%(54/57) in SG group; PGC+/MUC1+/MUC2+ and PGC-/MUC1+/MUC2+ phenotype took 43.9% (25/57) and 52.6% (30/57) in AG; the phenotypes in GC group appeared variable; extraordinarily, PGC-/MUC1-/MUC2+ phenotype took 100% (6/6) in MA or SRCC group and had a statistical significance compared with others (P < 0.05).

Conclusions

Phenotypes of PGC, MUC1 and MUC2 co-expression in dynamic gastric diseases are variable. In SG group it always showed PGC+/MUC1+/MUC2- phenotype and AG group showed two phenotypes (PGC+/MUC1+/MUC2+ and PGC-/MUC1+/MUC2+); the phenotypes in GC group appeared variable but the phenotype of PGC-/MUC1-/MUC2+ may be a predictive biomarker for diagnosing MA or SRCC, or distinguishing histological MA or SRCC from tubular adenocarcinoma accompanied by mucinous secretion or signet ring cell scattered distribution.

MUC1* ligand, NM23-H1, is a novel growth factor that maintains human stem cells in a more naïve state

We report that a single growth factor, NM23-H1, enables serial passaging of both human ES and iPS cells in the absence of feeder cells, their conditioned media or bFGF in a fully defined xeno-free media on a novel defined, xeno-free surface. Stem cells cultured in this system show a gene expression pattern indicative of a more “naïve” state than stem cells grown in bFGF-based media. NM23-H1 and MUC1* growth factor receptor cooperate to control stem cell self-replication. By manipulating the multimerization state of NM23-H1, we override the stem cell's inherent programming that turns off pluripotency and trick the cells into continuously replicating as pluripotent stem cells. Dimeric NM23-H1 binds to and dimerizes the extra cellular domain of the MUC1* transmembrane receptor which stimulates growth and promotes pluripotency. Inhibition of the NM23-H1/MUC1* interaction accelerates differentiation and causes a spike in miR-145 expression which signals a cell's exit from pluripotency.

Case-control study of single nucleotide polymorphisms of PSCA and MUC1 genes with gastric cancer in a Chinese

AIMS

A case-control study of 300 gastric cancer patients and 300 controls was conducted to investigate whether the polymorphisms rs2294008 in PSCA and rs2070803 in MUC1 might be associated with risk of gastric cancer in a Chinese population.

METHODS

Single nucleotide polymorphisms (SNPs) were genotyped using the Sequenom MassARRAY platform.

RESULTS

The data showed that the rs2294008 TT genotype increased gastric cancer risk to an adjusted odds ratio (OR) of 2.26 (95%CI 1.25-4.07), TC to 1.72 (95%CI 1.23-2.42) and TC/TT to 1.81 (95% CI 1.31-2.50), while the rs2070803 GA genotype was associated with a decrease in risk to an adjusted OR of 0.42 (95% CI 0.28-0.62) and rs2070803 GA / AA to 0.46 (95% CI 0.32-0.67). Further stratification analysis revealed that rs2294008 in PSCA consistently increased risk of both intestinal and diffuse-type gastric cancers. The effect of rs2070803 in MUC1 was noteworthily also consistent with both subtypes.

CONCLUSIONS

Our study suggested rs2294008 in the PSCA gene to be associated with increased risk of gastric cancer and rs2070803 in MUC1 to play a protective role in a Chinese population.

The use of a novel MUC1 antibody to identify cancer stem cells and circulating MUC1 in mice and patients with pancreatic cancer

BACKGROUND AND OBJECTIVES

MUC1 is over-expressed and aberrantly glycosylated in >60% of human pancreatic cancer (PC). Development of novel approaches for detection and/or targeting of MUC1 are critically needed and should be able to detect MUC1 on PC cells (including cancer stem cells) and in serum.

METHODS

The sensitivity and specificity of the anti-MUC1 antibody, TAB 004, was determined. CSCs were assessed for MUC1 expression using TAB 004-FITC on in vitro PC cell lines, and on lineage(-) cells from in vivo tumors and human samples. Serum was assessed for shed MUC1 via the TAB 004 EIA.

RESULTS

In vitro and in vivo, TAB 004 detected MUC1 on >95% of CSCs. Approximately, 80% of CSCs in patients displayed MUC1 expression as detected by TAB 004. Shed MUC1 was detected serum in mice with HPAF-II (MUC1(high) ) but not BxPC3 tumors (MUC1(low)). The TAB 004 EIA was able to accurately detect stage progression in PC patients.

CONCLUSIONS

The TAB 004 antibody may be explored as a therapeutic targeting agent for CSCs in PC. The TAB 004 EIA detected circulating MUC1 in a stage-dependent manner in patients with PC and thus may be explored as a PC stage diagnostic biomarker.

Genetic factors related to gastric cancer susceptibility identified using a genome-wide association study

Gastric cancer (GC) is one of the major malignant diseases worldwide, especially in Asia, where Japan and Korea have the highest incidence in the world. Gastric cancer is classified into intestinal and diffuse types. While the former is almost absolutely caused by Helicobacter pylori infection as the initial insult, the latter seems to include cases in which the role of infection is limited, if any, and a contribution of genetic factors is anticipated. Previously, we performed a genome-wide association study (GWAS) on diffuse-type GC by using single nucleotide polymorphisms (SNP) catalogued for Japanese population (JSNP), and identified a prostate stem cell antigen (PSCA) gene encoding a glycosylphosphatidylinositol-anchored cell surface antigen as a GC susceptibility gene. From the second candidate locus identified using the GWAS, 1q22, we found the Mucin 1 (MUC1) gene encoding a cell membrane-bound mucin protein as another gene related to diffuse-type GC. A two-allele analysis based on risk genotypes of the two genes revealed approximately 95% of Japanese population have at least one of the two risk genotypes, and approximately 56% of the population have both risk genotypes. The two-SNP genotype might offer ample room to further stratify a high GC risk subpopulation in Japan and Asia by adding another genetic and/or non-genetic factor. Recently, a GWAS on the Chinese population disclosed an additional three GC susceptibility loci: 3q13.31, 5p13.1 and 10q23.

Proteomic comparison of mcf-7 tumoursphere and monolayer cultures

Breast cancer is a heterogenous disease, composed of tumour cells with differing gene expressions and phenotypes. Very few antigens have been identified and a better understanding of tumour initiating-cells as targets for therapy is critically needed. Recently, a rare subpopulation of cells within tumours has been described with the ability to: (i) initiate and sustain tumour growth; (ii) resist traditional therapies and allow for secondary tumour dissemination; and (iii) display some of the characteristics of stem cells such as self-renewal. These cells are termed tumour-initiating cells or cancer stem cells, or alternatively, in the case of breast cancer, breast cancer stem cells. Previous studies have demonstrated that breast cancer stem cells can be enriched for in “tumoursphere” culture. Proteomics represents a novel way to investigate protein expression between cells. We hypothesise that characterisation of the proteome of the breast cancer line MCF-7 tumourspheres compared to adherent/differentiated cells identifies proteins of novel interest for further isolating or targeting breast cancer stem cells. We present evidence that: (i) the proteome of adherent cells is different to the proteome of cells grown in sphere medium from either early passage (passage 2) or late passage (passage 5) spheres; (ii) that spheres are enriched in expression of a variety of tumour-relevant proteins (including MUC1 and Galectin-3); and (iii) that targeting of one of these identified proteins (galectin-3) using an inhibitor (N-acetyllactosamine) decreases sphere formation/self-renewal of MCF-7 cancer stem cells in vitro and tumourigenicity in vivo. Hence, proteomic analysis of tumourspheres may find use in identifying novel targets for future therapy. The therapeutic targeting of breast cancer stem cells, a highly clinically relevant sub-population of tumour cells, has the potential to eliminate residual disease and may become an important component of a multi-modality treatment of cancer.

The MUC1 extracellular domain subunit is found in nuclear speckles and associates with spliceosomes

MUC1 is a large transmembrane glycoprotein and oncogene expressed by epithelial cells and overexpressed and underglycosylated in cancer cells. The MUC1 cytoplasmic subunit (MUC1-C) can translocate to the nucleus and regulate gene expression. It is frequently assumed that the MUC1 extracellular subunit (MUC1-N) does not enter the nucleus. Based on an unexpected observation that MUC1 extracellular domain antibody produced an apparently nucleus-associated staining pattern in trophoblasts, we have tested the hypothesis that MUC1-N is expressed inside the nucleus. Three different antibodies were used to identify MUC1-N in normal epithelial cells and tissues as well as in several cancer cell lines. The results of immunofluorescence and confocal microscopy analyses as well as subcellular fractionation, Western blotting, and siRNA/shRNA studies, confirm that MUC1-N is found within nuclei of all cell types examined. More detailed examination of its intranuclear distribution using a proximity ligation assay, subcellular fractionation, and immunoprecipitation suggests that MUC1-N is located in nuclear speckles (interchromatin granule clusters) and closely associates with the spliceosome protein U2AF65. Nuclear localization of MUC1-N was abolished when cells were treated with RNase A and nuclear localization was altered when cells were incubated with the transcription inhibitor 5,6-dichloro-1-b-d-ribofuranosylbenzimidazole (DRB). While MUC1-N predominantly associated with speckles, MUC1-C was present in the nuclear matrix, nucleoli, and the nuclear periphery. In some nuclei, confocal microscopic analysis suggest that MUC1-C staining is located close to, but only partially overlaps, MUC1-N in speckles. However, only MUC1-N was found in isolated speckles by Western blotting. Also, MUC1-C and MUC1-N distributed differently during mitosis. These results suggest that MUC1-N translocates to the nucleus where it is expressed in nuclear speckles and that MUC1-N and MUC1-C have dissimilar intranuclear distribution patterns.

Intrinsic and acquired resistance to HER2-targeted therapies in HER2 gene-amplified breast cancer: mechanisms and clinical implications

Approximately 25% of human breast cancers overexpress the HER2 (ErbB2) proto-oncogene, which confers a more aggressive tumor phenotype and associates with a poor prognosis in patients with this disease. Two approved therapies targeting HER2, the monoclonal antibody trastuzumab and the tyrosine kinase inhibitor lapatinib, are clinically active against this type of breast cancer. However, a significant fraction of patients with HER2+ breast cancer treated with these agents eventually relapse or develop progressive disease. This suggests that tumors acquire or possess intrinsic mechanisms of resistance that allow escape from HER2 inhibition. This review focuses on mechanisms of intrinsic and/or acquired resistance to HER2-targeted therapies that have been identified in preclinical and clinical studies. These mechanisms involve alterations to HER2 itself, coexpression or acquisition of bypass signaling through other receptor or intracellular signaling pathways, defects in mechanisms of cell cycle regulation or apoptosis, and host factors that may modulate drug response. Emerging clinical evidence already suggests that combinations of therapies targeting HER2 as well as these resistance pathways will be effective in overcoming or preventing resistance.

Increased signalling of EGFR and IGF1R, and deregulation of PTEN/PI3K/Akt pathway are related with trastuzumab resistance in HER2 breast carcinomas

Background:

Trastuzumab resistance hampers its well-known efficacy to control HER2-positive breast cancer. The involvement of PI3K/Akt pathway in this mechanism is still not definitively confirmed.

Methods:

We selected 155 patients treated with trastuzumab after development of metastasis or as adjuvant/neoadjuvant therapy. We performed immunohistochemistry for HER2, ER/PR, epidermal growth factor 1-receptor (EGFR), α-insulin-like growth factor 1-receptor (IGF1R), phosphatase and tensin homologue (PTEN), p110α, pAkt, pBad, pmTOR, pMAPK, MUC1, Ki67, p53 and p27; mutational analysis of PIK3CA and PTEN, and PTEN promoter hypermethylation.

Results:

We found 46% ER/PR-positive tumours, overexpression of EGFR (15%), α-IGF1R (25%), p110α (19%), pAkt (28%), pBad (22%), pmTOR (23%), pMAPK (24%), MUC1 (80%), PTEN loss (20%), and PTEN promoter hypermethylation (20%). PIK3CA and PTEN mutations were detected in 17% and 26% tumours, respectively. Patients receiving adjuvant trastuzumab with α-IGF1R or pBad overexpressing tumours presented shorter progression-free survival (PFS) (all P⩽0.043). Also, p110α and mTOR overexpression, liver and brain relapses implied poor overall survival (OS) (all P⩽0.041). In patients with metastatic disease, decreased PFS correlated with p110α expression (P=0.024), whereas for OS were the presence of vascular invasion and EGFR expression (P⩽0.019; Cox analysis).

Conclusion:

Our results support that trastuzumab resistance mechanisms are related with deregulation of PTEN/PI3K/Akt/mTOR pathway, and/or EGFR and IGF1R overexpression in a subset of HER2-positive breast carcinomas.

NME genes in epithelial morphogenesis

The NME family of genes encodes highly conserved multifunctional proteins that have been shown to participate in nucleic acid metabolism, energy homeostasis, cell signaling, and cancer progression. Some family members, particularly isoforms 1 and 2, have attracted extensive interests because of their potential anti-metastasis activity. Unfortunately, there have been few consensus mechanistic explanations for this critical function because of the numerous molecular functions ascribed to these proteins, including nucleoside diphosphate kinase, protein kinase, nuclease, transcription factor, growth factor, among others. In addition, different studies showed contradictory prognostic correlations between NME expression levels and tumor progression in clinical samples. Thus, analyses using pliable in vivo systems have become critical for unraveling at least some aspects of the complex functions of this family of genes. Recent works using the Drosophila genetic system have suggested a role for NME in regulating epithelial cell motility and morphogenesis, which has also been demonstrated in mammalian epithelial cell culture. This function is mediated by promoting internalization of growth factor receptors in motile epithelial cells, and the adherens junction components such as E-cadherin and β-catenin in epithelia that form the tissue linings. Interestingly, NME genes in epithelial cells appear to function in a defined range of expression levels. Either down-regulation or over-expression can perturb epithelial integrity, resulting in different aspects of epithelial abnormality. Such biphasic functions provide a plausible explanation for the documented anti-metastatic activity and the suspected oncogenic function. This review summarizes these recent findings and discusses their implications.

Extracellular NM23 Protein as a Therapeutic Target for Hematologic Malignancies

An elevated serum level of NM23-H1 protein is a poor prognostic factor in patients with various hematologic malignancies. The extracellular NM23-H1 protein promotes the in vitro growth and survival of acute myelogenous leukemia (AML) cells and inversely inhibits the in vitro survival of normal peripheral blood monocytes in primary culture at concentrations equivalent to the levels found in the serum of AML patients. The growth and survival promoting activity to AML cells is associated with cytokine production and activation of mitogen-activated protein kinases (MAPKs) and signal transducers and activators of transcription (STAT) signaling pathways. Inhibitors specific for MAPK signaling pathways inhibit the growth/survival-promoting activity of NM23-H1. These findings indicate a novel biological action of extracellular NM23-H1 and its association with poor prognosis. These results suggest an important role of extracellular NM23-H1 in the malignant progression of leukemia and a potential therapeutic target for these malignancies.