Notch1 regulates the functional contribution of RhoC to cervical carcinoma progression

Targeting anoikis resistance as a strategy for cancer therapy

Anoikis, known as matrix detachment-induced apoptosis or detachment-induced cell death, is crucial for tissue development and homeostasis. Cancer cells develop means to evade anoikis, e.g. anoikis resistance, thereby allowing for cells to survive under anchorage-independent conditions. Uncovering the mechanisms of anoikis resistance will provide details about cancer metastasis, and potential strategies against cancer cell dissemination and metastasis. Here, we summarize the principal elements and core molecular mechanisms of anoikis and anoikis resistance. We discuss the latest progress of how anoikis and anoikis resistance are regulated in cancers. Furthermore, we summarize emerging data on selective compounds and nanomedicines, explaining how inhibiting anoikis resistance can serve as a meaningful treatment modality against cancers. Finally, we discuss the key limitations of this therapeutic paradigm and possible strategies to overcome them. In this review, we suggest that pharmacological modulation of anoikis and anoikis resistance by bioactive compounds could surmount anoikis resistance, highlighting a promising therapeutic regimen that could be used to overcome anoikis resistance in cancers.

Rhogef17: A novel target for endothelial barrier function

ARHGEF17 encodes the protein RhoGEF17, which is highly expressed in vascular endothelial cells. It is a guanine nucleotide exchange factor (GEF) that accelerates the exchange of GDP with GTP on many small GTPases through its Dbl homology (DH) domain, enabling the activation of Rho-GTPases such as RhoA, RhoB, and RhoC. Rho GTPase-regulated changes in the actin cytoskeleton and cell adhesion kinetics are the main mechanisms mediating many endothelial cell (EC) alterations, including cell morphology, migration, and division changes, which profoundly affect EC barrier function. This review focuses on ARHGEF17 expression, activation and biological functions in ECs, linking its regulation of cellular morphology, migration, mitosis and other cellular behaviors to disease onset and progression. Understanding ARHGEF17 mechanisms of action will contribute to the design of therapeutic approaches targeting RhoGEF17, a potential drug target for the treatment of various endothelium-related diseases, Such as vascular inflammation, carcinogenesis and transendothelial metastasis of tumors.

Anoikis-related signature identifies tumor microenvironment landscape and predicts prognosis and drug sensitivity in colorectal cancer

Background: Anoikis, a mechanism of programmed apoptosis, plays an important role in growth and metastasis of tumors. However, there are still few available comprehensive reports on the impact of anoikis on colorectal cancer. Method: A clustering analysis was done on 133 anoikis-related genes in GSE39582, and we compared clinical features between clusters, the tumor microenvironment was analyzed with algorithms such as "Cibersort" and "ssGSEA". We investigated risk scores of clinical feature groups and anoikis-associated gene mutations after creating a predictive model. We incorporated clinical traits to build a nomogram. Additionally, the quantitative real-time PCR was employed to investigate the mRNA expression of selected anoikis-associated genes. Result: We identified two anoikis-related clusters with distinct prognoses, clinical characteristics, and biological functions. One of the clusters was associated with anoikis resistance, which activated multiple pathways encouraging tumor metastasis. In our prognostic model, oxaliplatin may be a sensitive drug for low-risk patients. The nomogram showed good ability to predict survival time. And SIRT3, PIK3CA, ITGA3, DAPK1, and CASP3 increased in CRC group through the PCR assay. Conclusion: Our study identified two distinct modes of anoikis in colorectal cancer, with active metastasis-promoting pathways inducing an anti-anoikis subtype, which has a stronger propensity for metastasis and a worse prognosis than an anoikis-activated subtype. Massive immune cell infiltration may be an indicator of anoikis resistance. Anoikis' role in the colorectal cancer remains to be investigated.

RhoC in association with TET2/WDR5 regulates cancer stem cells by epigenetically modifying the expression of pluripotency genes

Emerging evidence illustrates that RhoC has divergent roles in cervical cancer progression where it controls epithelial to mesenchymal transition (EMT), migration, angiogenesis, invasion, tumor growth, and radiation response. Cancer stem cells (CSCs) are the primary cause of recurrence and metastasis and exhibit all of the above phenotypes. It, therefore, becomes imperative to understand if RhoC regulates CSCs in cervical cancer. In this study, cell lines and clinical specimen-based findings demonstrate that RhoC regulates tumor phenotypes such as clonogenicity and anoikis resistance. Accordingly, inhibition of RhoC abrogated these phenotypes. RNA-seq analysis revealed that RhoC over-expression resulted in up-regulation of 27% of the transcriptome. Further, the Infinium MethylationEPIC array showed that RhoC over-expressing cells had a demethylated genome. Studies divulged that RhoC via TET2 signaling regulated the demethylation of the genome. Further investigations comprising ChIP-seq, reporter assays, and mass spectrometry revealed that RhoC associates with WDR5 in the nucleus and regulates the expression of pluripotency genes such as Nanog. Interestingly, clinical specimen-based investigations revealed the existence of a subset of tumor cells marked by RhoC+/Nanog+ expression. Finally, combinatorial inhibition (in vitro) of RhoC and its partners (WDR5 and TET2) resulted in increased sensitization of clinical specimen-derived cells to radiation. These findings collectively reveal a novel role for nuclear RhoC in the epigenetic regulation of Nanog and identify RhoC as a regulator of CSCs. The study nominates RhoC and associated signaling pathways as therapeutic targets.

Deletion of Meg8-DMR Enhances Migration and Invasion of MLTC-1 Depending on the CTCF Binding Sites

The Dlk1-Dio3 imprinted domain on mouse chromosome 12 contains three well-characterized paternally methylated differentially methylated regions (DMRs): IG-DMR, Gtl2-DMR, and Dlk1-DMR. These DMRs control the expression of many genes involved in embryonic development, inherited diseases, and human cancer in this domain. The first maternal methylation DMR discovered in this domain was the Meg8-DMR, the targets and biological function of which are still unknown. Here, using an enhancer-blocking assay, we first dissected the functional parts of the Meg8-DMR and showed that its insulator activity is dependent on the CCCTC-binding factor (CTCF) in MLTC-1. Results from RNA-seq showed that the deletion of the Meg8-DMR and its compartment CTCF binding sites, but not GGCG repeats, lead to the downregulation of numerous genes on chromosome 12, in particular the drastically reduced expression of Dlk1 and Rtl1 in the Dlk1-Dio3 domain, while differentially expressed genes are enriched in the MAPK pathway. In vitro assays revealed that the deletion of the Meg8-DMR and CTCF binding sites enhances cell migration and invasion by decreasing Dlk1 and activating the Notch1-Rhoc-MAPK/ERK pathway. These findings enhance research into gene regulation in the Dlk1-Dio3 domain by indicating that the Meg8-DMR functions as a long-range regulatory element which is dependent on CTCF binding sites and affects multiple genes in this domain.

Abnormal activation of notch 1 signaling causes apoptosis resistance in cervical cancer

Notch1 signaling pathway is an evolutionarily conserved and crucial regulator to determine cell fate and differentiation. Notch1 is often over expressed in several cancers, which plays an essential for cancer cell proliferation, survival, invasion and metastasis. The oncogenic function of Notch1 signaling in cervical cancer progression is not well-characterized. In the present study, we showed that Notch1 is significantly enhanced in cervical cancer tissues. Similarly, the relative mRNA and expression of Notch1 protein are significantly upregulated in cervical cancer cell lines such as HeLa and SiHa. Further, we have performed RNAi for NOTCH1 depletion to determine its specific role in cervical cancer progression. Flow cytometry analysis revealed that NOTCH1 depletion leads to activation of apoptotic cell death in cervical cancer. Further, the NOTCH1 depleted cells showed increased sensitivity towards DNA-targeting drugs and therefore cell viability was reduced efficiently. Altogether, our findings suggest that Notch1 overexpression in cervical cancer cells was involved in tumorigenesis and apoptosis resistance of cervical cancer.

Targeting Notch to Maximize Chemotherapeutic Benefits: Rationale, Advanced Strategies, and Future Perspectives

Simple Summary

The Notch signaling pathway regulates cell proliferation, apoptosis, stem cell self-renewal, and differentiation in a context-dependent fashion both during embryonic development and in adult tissue homeostasis. Consistent with its pleiotropic physiological role, unproper activation of the signaling promotes or counteracts tumor pathogenesis and therapy response in distinct tissues. In the last twenty years, a wide number of studies have highlighted the anti-cancer potential of Notch-modulating agents as single treatment and in combination with the existent therapies. However, most of these strategies have failed in the clinical exploration due to dose-limiting toxicity and low efficacy, encouraging the development of novel agents and the design of more appropriate combinations between Notch signaling inhibitors and chemotherapeutic drugs with improved safety and effectiveness for distinct types of cancer.

Abstract

Notch signaling guides cell fate decisions by affecting proliferation, apoptosis, stem cell self-renewal, and differentiation depending on cell and tissue context. Given its multifaceted function during tissue development, both overactivation and loss of Notch signaling have been linked to tumorigenesis in ways that are either oncogenic or oncosuppressive, but always context-dependent. Notch signaling is critical for several mechanisms of chemoresistance including cancer stem cell maintenance, epithelial-mesenchymal transition, tumor-stroma interaction, and malignant neovascularization that makes its targeting an appealing strategy against tumor growth and recurrence. During the last decades, numerous Notch-interfering agents have been developed, and the abundant preclinical evidence has been transformed in orphan drug approval for few rare diseases. However, the majority of Notch-dependent malignancies remain untargeted, even if the application of Notch inhibitors alone or in combination with common chemotherapeutic drugs is being evaluated in clinical trials. The modest clinical success of current Notch-targeting strategies is mostly due to their limited efficacy and severe on-target toxicity in Notch-controlled healthy tissues. Here, we review the available preclinical and clinical evidence on combinatorial treatment between different Notch signaling inhibitors and existent chemotherapeutic drugs, providing a comprehensive picture of molecular mechanisms explaining the potential or lacking success of these combinations.

Notch Signaling Pathway in Cancer-Review with Bioinformatic Analysis

Simple Summary

The Notch signaling pathway, which controls multiple cell differentiation processes during the embryonic stage and adult life, is associated with carcinogenesis and disease progression. The aim of the present study was to highlight cancer heterogeneity with respect to the Notch pathway. Our analysis concerns the effects of the Notch signaling at different levels, including core components and downstream target genes. We also demonstrate overall and disease-free survival results, pointing out the characteristics of particular Notch components. Depending on tissue context, Notch members can be either oncogenic or suppressive. We observed different expression profile core components and target genes that could be associated with distinct survival of patients. Advances in our understanding of the Notch signaling in cancer are very promising for the development of new treatment strategies for the benefit of patients.

Abstract

Notch signaling is an evolutionarily conserved pathway regulating normal embryonic development and homeostasis in a wide variety of tissues. It is also critically involved in carcinogenesis, as well as cancer progression. Activation of the Notch pathway members can be either oncogenic or suppressive, depending on tissue context. The present study is a comprehensive overview, extended with a bioinformatics analysis of TCGA cohorts, including breast, bladder, cervical, colon, kidney, lung, ovary, prostate and rectum carcinomas. We performed global expression profiling of the Notch pathway core components and downstream targets. For this purpose, we implemented the Uniform Manifold Approximation and Projection algorithm to reduce the dimensions. Furthermore, we determined the optimal cutpoint using Evaluate Cutpoint software to established disease-free and overall survival with respect to particular Notch members. Our results demonstrated separation between tumors and their corresponding normal tissue, as well as between tumors in general. The differentiation of the Notch pathway, at its various stages, in terms of expression and survival resulted in distinct profiles of biological processes such as proliferation, adhesion, apoptosis and epithelial to mesenchymal transition. In conclusion, whether oncogenic or suppressive, Notch signaling is proven to be associated with various types of malignancies, and thus may be of interest as a potential therapeutic target.

Functional Gene Expression Differentiation of the Notch Signaling Pathway in Female Reproductive Tract Tissues-A Comprehensive Review With Analysis

The Notch pathway involves evolutionarily conserved signaling regulating the development of the female tract organs such as breast, ovary, cervix, and uterine endometrium. A great number of studies revealed Notch aberrancies in association with their carcinogenesis and disease progression, the management of which is still challenging. The present study is a comprehensive review of the available literature on Notch signaling during the normal development and carcinogenesis of the female tract organs. The review has been enriched with our analyses of the TCGA data including breast, cervical, ovarian, and endometrial carcinomas concerning the effects of Notch signaling at two levels: the core components and downstream effectors, hence filling the lack of global overview of Notch-driven carcinogenesis and disease progression. Phenotype heterogeneity regarding Notch signaling was projected in two uniform manifold approximation and projection algorithm dimensions, preceded by the principal component analysis step reducing the data burden. Additionally, overall and disease-free survival analyses were performed with the optimal cutpoint determination by Evaluate Cutpoints software to establish the character of particular Notch components in tumorigenesis. In addition to the review, we demonstrated separate models of the examined cancers of the Notch pathway and its targets, although expression profiles of all normal tissues were much more similar to each other than to its cancerous compartments. Such Notch-driven cancerous differentiation resulted in a case of opposite association with DFS and OS. As a consequence, target genes also show very distinct profiles including genes associated with cell proliferation and differentiation, energy metabolism, or the EMT. In conclusion, the observed Notch associations with the female tract malignancies resulted from differential expression of target genes. This may influence a future analysis to search for new therapeutic targets based on specific Notch pathway profiles.

Rho GTPases in Gynecologic Cancers: In-Depth Analysis toward the Paradigm Change from Reactive to Predictive, Preventive, and Personalized Medical Approach Benefiting the Patient and Healthcare

Rho guanosine triphospatases (GTPases) resemble a conserved family of GTP-binding proteins regulating actin cytoskeleton dynamics and several signaling pathways central for the cell. Rho GTPases create a so-called Ras-superfamily of GTPases subdivided into subgroups comprising at least 20 members. Rho GTPases play a key regulatory role in gene expression, cell cycle control and proliferation, epithelial cell polarity, cell migration, survival, and apoptosis, among others. They also have tissue-related functions including angiogenesis being involved in inflammatory and wound healing processes. Contextually, any abnormality in the Rho GTPase function may result in severe consequences at molecular, cellular, and tissue levels. Rho GTPases also play a key role in tumorigenesis and metastatic disease. Corresponding mechanisms include a number of targets such as kinases and scaffold/adaptor-like proteins initiating GTPases-related signaling cascades. The accumulated evidence demonstrates the oncogenic relevance of Rho GTPases for several solid malignancies including breast, liver, bladder, melanoma, testicular, lung, central nervous system (CNS), head and neck, cervical, and ovarian cancers. Furthermore, Rho GTPases play a crucial role in the development of radio- and chemoresistance e.g. under cisplatin-based cancer treatment. This article provides an in-depth overview on the role of Rho GTPases in gynecological cancers, highlights relevant signaling pathways and pathomechanisms, and sheds light on their involvement in tumor progression, metastatic spread, and radio/chemo resistance. In addition, insights into a spectrum of novel biomarkers and innovative approaches based on the paradigm shift from reactive to predictive, preventive, and personalized medicine are provided.

Notch signalling in cervical cancer

The initial discovery of key developmental signalling pathways, largely using classical genetic approaches in model organisms, was followed by an intense burst of characterisation of the molecular components. Studies also began demonstrating a role for these pathways in oncogenesis. Patterns of mutations in Notch pathway components, such as those reported in subsets of hematological malignancies, have been easier to study, and the cumulative information is leading to potentially new therapies. However, it has been more challenging to clearly define the role of the Notch pathway in human solid tumours, given the absence of widespread specific activating or repressive mutations in key components of the pathway. In this review, we trace more than two decades of work looking at the role of Notch signalling in human cervical cancer progression. We document the contrasting reports on a tumour suppressive role and pro-oncogenic role in cervical cancers. However, an analysis of recent genomic data strikingly shows both widespread features of Notch expression and genetic changes that largely amplify positive regulators and delete negative controllers of the Notch pathway. This analysis reinforces a largely pro-oncogenic role for Notch signalling and lays the foundation for a nuanced exploration of synergistic and targeted therapies. Lastly, we further trace some of the complex challenges in advanced cervical cancer progression, including issues of cancer stem cells and metastasis.

RhoC regulates radioresistance via crosstalk of ROCK2 with the DNA repair machinery in cervical cancer

Background

Radioresistance remains a challenge to the successful treatment of various tumors. Intrinsic factors like alterations in signaling pathways regulate response to radiation. RhoC, which has been shown to modulate several tumor phenotypes has been investigated in this report for its role in radioresistance. In vitro and clinical sample-based studies have been performed to understand its contribution to radiation response in cervical cancer and this is the first report to establish the role of RhoC and its effector ROCK2 in cervical cancer radiation response.

Methods

Biochemical, transcriptomic and immunological approaches including flow cytometry and immunofluorescence were used to understand the role of RhoC and ROCK2. RhoC variants, siRNA and chemical inhibitors were used to alter the function of RhoC and ROCK2. Transcriptomic profiling was performed to understand the gene expression pattern of the cells. Live sorting using an intracellular antigen has been developed to isolate the cells for transcriptomic studies.

Results

Enhanced expression of RhoC conferred radioprotection on the tumor cells while inhibition of RhoC resulted in sensitization of cells to radiation. The RhoC overexpressing cells had a better DNA repair machinery as observed using transcriptomic analysis. Similarly, overexpression of ROCK2, protected tumor cells against radiation while its inhibition increased radiosensitivity in vitro. Further investigations revealed that ROCK2 inhibition abolished the radioresistance phenotype, conferred by RhoC on SiHa cells, confirming that it is a downstream effector of RhoC in this context. Additionally, transcriptional analysis of the live sorted ROCK2 high and ROCK2 low expressing SiHa cells revealed an upregulation of the DNA repair pathway proteins. Consequently, inhibition of ROCK2 resulted in reduced expression of pH2Ax and MRN complex proteins, critical to repair of double strand breaks. Clinical sample-based studies also demonstrated that ROCK2 inhibition sensitizes tumor cells to irradiation.

Conclusions

Our data primarily indicates that RhoC and ROCK2 signaling is important for the radioresistance phenotype in cervical cancer tumor cells and is regulated via association of ROCK2 with the proteins of DNA repair pathway involving pH2Ax, MRE11 and RAD50 proteins, partly offering insights into the mechanism of radioresistance in tumor cells. These findings highlight RhoC-ROCK2 signaling involvement in DNA repair and urge the need for development of these molecules as targets to alleviate the non-responsiveness of cervical cancer tumor cells to irradiation treatment.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1385-7) contains supplementary material, which is available to authorized users.

RhoC: a fascinating journey from a cytoskeletal organizer to a Cancer stem cell therapeutic target

Tumor heterogeneity results in differential response to therapy due to the existence of plastic tumor cells, called cancer stem cells (CSCs), which exhibit the property of resistance to therapy, invasion and metastasis. These cells have a distinct, signaling network active at every stage of progression. It is difficult to envisage that the CSCs will have a unique set of signaling pathways regulating every stage of disease progression. Rather, it would be easier to believe that a single pivotal pathway having significant contribution at every stage, which can further turn on a battery of signaling mechanisms specific to that stage, would be instrumental in regulating the signaling network, enabling easy transition from one state to another. In this context, we discuss the role of RhoC which has contributed to several phenotypes during tumor progression.

RhoC (Ras homolog gene family member C) has been widely reported to regulate actin organization. It has been shown to impact the motility of cancer cells, resultantly affecting invasion and metastasis, and has contributed to carcinoma progression of the breast, pancreas, lung, ovaries and cervix, among several others. The most interesting finding has been its indispensable role in metastasis. Also, it has the ability to modulate various other phenotypes like angiogenesis, motility, invasion, metastasis, and anoikis resistance. These observations suggest that RhoC imparts the plasticity required by tumor cells to exhibit such diverse functions based on microenvironmental cues. This was further confirmed by recent reports which show that it regulates cancer stem cells in breast, ovary and head and neck cancers. Studies also suggest that the inhibition of RhoC results in abolition of advanced tumor phenotypes.

Our review throws light on how RhoC, which is capable of modulating various phenotypes may be the apt core signaling candidate regulating disease progression. Additionally, mice studies show that RhoC is not essential for embryogenesis, giving scope for its development as a possible therapeutic target. This review thus stresses on the need to understand the protein and its functioning in greater detail to enable its development as a stem cell marker and a possible therapeutic target.

The Comparison of RhoC and PI3K Gene Expression on the Breast Cancer Tissue and Benign Tumour Tissue

BACKGROUND:

The expression of a gene is a process that conveys information of genes to synthesise gene product is functional. Alterations of the molecular biology in breast cancer are very complex because of many factors play a role in the tumorigenesis. RhoC is a prometastases gene. The PI3K gene is crucial in the regulation of multiple cellular functions, including cell growth, proliferation, metabolism and angiogenesis.

AIM:

This study aims to compare of RhoC and PI3K gene expression on the breast cancer tissue and benign tumour tissue.

MATERIAL AND METHODS:

Expression of the RhoC and PI3K genes was carried out with qPCR. The absolute quantification method was using breast cancer tissue. As a comparison, benign tumours (FATs) tissue was carried out. The standard curves were obtained from cloning target genes, which were inserted into the gGEMT-easy vector from E. coli. The gene expression data was carried out by t-test to see the mean difference between the expression of breast cancer tissue and benign tumours (FATs) with a value of p ≤ 0.005 in RhoC and PI3K gene expression. And the relationship between expressions was done by Pearson correlation test.

RESULTS:

The results showed that it was found that PI3K gene expression on breast cancer tissue was higher than the number in a benign tumour (fibroadenoma mammae) as an endogenous control. And also, the expression of RhoC is much lower on breast cancer tissue compared with a benign tumour.

CONCLUSION:

This study concluded that expression of RhoC affects the expression of PI3K so that the thing this is what causes the proliferation and began to provide support aggressive cancer cells in the breast.

Ectopic expression of CC chemokine receptor 7 promotes prostate cancer cells metastasis via Notch1 signaling

There currently exists no satisfactory treatment for patients with prostate cancer with local evolution and distant metastasis. Previous studies have confirmed the importance of CC chemokine receptor 7 (CCR7) in the invasion and metastasis of prostate cancer. And increasing evidence prove that Notch1 can play diametrically opposite roles in the development and progression of different tumors. To demonstrate the correlation between CCR7 and Notch1, PC-3 cells were transfected with pcDNA3.1-CCR7 or CCR7 si-RNA, respectively. Then Western blot analysis was used to detect the expressions of Notch1, ERK, P38, JNK, NF-κB, MMP-9, and epithelial-mesenchymal transition (EMT)-related proteins. Moreover, matrigel invasion assays were performed to assess the migratory and invasive activities of PC-3 cells. PcDNA3.1-CCR7 increased the expression of Notch1, phospho-MAPK, phospho-P65, MMP-9, N-cadherin, and Snail in PC-3 cells, but decreased the expression of E-cadherin. PcDNA3.1-CCR7 also promoted the migration and invasion of PC-3 cells. However, CCR7 si-RNA reversed the effect of pcDNA3.1-CCR7 in PC-3 cells. And MAPK and NF-κB pathway inhibitors were used to testify that activation of Notch1 induces EMT through MAPK and NF-κB pathway. All these results indicate that upregulation of Notch1 by CCR7 can accelerate the evolution of EMT and develop the invasion and metastasis in prostate cancer cells by activating MAPK and NF-κB signaling pathways in prostate cancer cells, which provides a new molecular evidence for targeted therapy in metastatic prostate cancer.

The correlation analysis of miRNAs and target genes in metastasis of cervical squamous cell carcinoma

Aim: This study was intended to identify the metastasis-related miRNAs and target genes in cervical squamous cell carcinoma. Materials & methods: The mRNA and miRNA next-generation sequencing data were downloaded. Differential expression analysis was carried out, followed by target gene prediction of differentially expressed miRNAs. The biological function of differentially expressed genes was performed. Validation was carried out by survival analysis and qRT-PCR. Results: N4BP3 were associated with the survival time of patients. Hsa-mir-451 and hsa-mir-486 were related to tumor differentiation stage. Validated expression of hsa-mir-24–2, hsa-mir-582, NOTCH1, PIP4K2B, DIP2B and IGFBP5 was consistent with the bioinformatics analysis. Conclusion: Alterations of miRNAs and target genes may be useful in understanding the metastasis mechanisms of cervical squamous cell carcinoma.

Alcohol and Cancer Stem Cells

Heavy alcohol consumption has been associated with increased risk of several cancers, including cancer of the colon, rectum, female breast, oral cavity, pharynx, larynx, liver, and esophagus. It appears that alcohol exposure not only promotes carcinogenesis but also enhances the progression and aggressiveness of existing cancers. The molecular mechanisms underlying alcohol tumor promotion, however, remain unclear. Cancer stem cells (CSC), a subpopulation of cancer cells with self-renewal and differentiation capacity, play an important role in tumor initiation, progression, metastasis, recurrence, and therapy resistance. The recent research evidence suggests that alcohol increases the CSC population in cancers, which may underlie alcohol-induced tumor promotion. This review discusses the recent progress in the research of alcohol promotion of CSC and underlying cellular/molecular mechanisms. The review will further explore the therapeutic potential of CSC inhibition in treating alcohol-induced tumor promotion.

Cellular and molecular mechanisms underlying alcohol-induced aggressiveness of breast cancer

Breast cancer is a leading cause of morbidity and mortality in women. Both Epidemiological and experimental studies indicate a positive correlation between alcohol consumption and the risk of breast cancer. While alcohol exposure may promote the carcinogenesis or onset of breast cancer, it may as well enhance the progression and aggressiveness of existing mammary tumors. Recent progress in this line of research suggests that alcohol exposure is associated with invasive breast cancer and promotes the growth and metastasis of mammary tumors. There are multiple potential mechanisms involved in alcohol-stimulated progression and aggressiveness of breast cancer. Alcohol may increase the mobility of cancer cells by inducing cytoskeleton reorganization and enhancing the cancer cell invasion by causing degradation and reconstruction of the extracellular matrix (ECM). Moreover, alcohol may promote the epithelial-mesenchymal transition (EMT), a hallmark of malignancy, and impair endothelial integrity, thereby increasing the dissemination of breast cancer cells and facilitating metastasis. Furthermore, alcohol may stimulate tumor angiogenesis through the activation of cytokines and chemokines which promotes tumor growth. Additionally, alcohol may increase the cancer stem cell population which affects neoplastic cell behavior, aggressiveness, and the therapeutic response. Alcohol can be metabolized in the mammary tissues and breast cancer cells which produces reactive oxygen species (ROS), causing oxidative stress. Recent studies suggest that the epidermal growth factor receptor (EGFR) family, particularly ErbB2 (a member of this family), is involved in alcohol-mediated tumor promotion. Breast cancer cells or mammary epithelial cells over-expressing ErbB2 are more sensitive to alcohol's tumor promoting effects. There is considerable cross-talk between oxidative stress and EGFR/ErbB2 signaling. This review further discusses how the interaction between oxidative stress and EGFR/ErbB2 signaling contributes to the cellular and molecular events associated with breast cancer aggressiveness. We also discuss the potential therapeutic approaches for cancer patients who drink alcoholic beverages.

Cancer Stem Cells and Radioresistance: Rho/ROCK Pathway Plea Attention

Radiation is the most potent mode of cancer therapy; however, resistance to radiation therapy results in tumor relapse and subsequent fatality. The cancer stem cell (CSC), which has better DNA repair capability, has been shown to contribute to tumor resistance and is an important target for treatment. Signaling molecules such as Notch, Wnt, and DNA repair pathways regulate molecular mechanisms in CSCs; however, none of them have been translated into therapeutic targets. The RhoGTPases and their effector ROCK-signaling pathway, though important for tumor progression, have not been well studied in the context of radioresistance. There are reports that implicate RhoA in radioresistance. ROCK2 has also been shown to interact with BRCA2 in the regulation of cell division. Incidentally, statins (drug for cardiovascular ailment) are functional inhibitors of RhoGTPases. Studies suggest that patients on statins have a better prognosis in cancers. Data from our lab suggest that ROCK signaling regulates radioresistance in cervical cancer cells. Collectively, these findings suggest that Rho/ROCK signaling may be important for radiation resistance. In this review, we enumerate the role of Rho/ROCK signaling in stemness and radioresistance and highlight the need to explore these molecules for a better understanding of radioresistance and development of therapeutics.

Clinicopathological significance of Notch1 expression in cervical cancer patients: a meta-analysis

Aim: Notch1 expression remains incompatible and contradictory with previous findings on cervical cancer. The purpose of this study is to evaluate the association between Notch1 and cervical cancer. Methods: Available studies were searched from diverse databases and Review Managers 5.3 software was used to perform analysis. Results: A total of 798 samples were included in this meta-analysis. The Notch1 expression in cancer tissues was higher than that in precancer (p = 0.0003) and normal tissues (p < 0.02). However, the difference of Notch1 expression between cancer cases and precancer cases has no statistical significance (p = 0.35). Moreover, lymph node metastasis (p = 0.02) was associated with higher Notch1 expression in cervical cancer. Conclusion: Notch1 over-expression indicated aggressive biological behaviors.

Astrocyte elevated gene-1 promotes progression of cervical squamous cell carcinoma by inducing epithelial-mesenchymal transition via Wnt signaling

OBJECTIVE

The aim of this study was to investigate the association of astrocyte elevated gene-1 (AEG-1) with epithelial-mesenchymal transition of cervical squamous cell carcinoma (CSCC) and the underlying mechanisms.

METHODS

The expression of proteins was determined by immunohistochemistry in tissues. Overexpression and knockdown of AEG-1 in SiHa cells were achieved by stable AEG-1 gene transfection (SiHa-AEG-1+) and AEG-1-siRNA (SiHa-AEG-1-), respectively. The cellular levels of messenger RNA and proteins were assessed with reverse transcription polymerase chain reaction and Western blotting, respectively. The cell invasion capacity was assessed by the chamber invasion assay.

RESULTS

AEG-1 was overexpressed in clinical CSCC and associated with lymph node metastasis, parametrial involvement, stromal invasion, and vascular invasion. A high level of vimentin and a low level of E-cadherin were also detected in the cancer tissues. AEG-1 expression was positively correlated with vimentin expression and negatively with E-cadherin expression in CSCC tissues. In addition, high level of AEG-1 was related to unfavorable prognosis of CSCC. On a cellular level, overexpression of AEG-1 was found to lead to an up-regulation of vimentin and a down-regulation of E-cadherin on messenger RNA and protein level in SiHa cells, whereas AEG-1 knockdown led to a contrary result. Meanwhile, the nuclear levels of NF-κB p65 and β-catenin were also increased in SiHa-AEG-1+, whereas their nuclear levels were decreased in SiHa-AEG-1-. Inhibition of Wnt signaling significantly reduced vimentin level and enhanced E-cadherin level in SiHa-AEG+, but inhibition of NF-κB signaling did not. SiHa-AEG-1+ and SiHa-AEG- showed an enhanced and a decreased invasive capacity, respectively. The enhanced invasiveness of SiHa-AEG-1+ was weakened by inhibition of Wnt signaling.

CONCLUSIONS

AEG-1 was associated with the progression of CSCC by promoting epithelial-mesenchymal transition via Wnt signaling pathway.

EMT-Inducing Molecular Factors in Gynecological Cancers

Gynecologic cancers are the unregulated growth of neoplastic cells that arise in the cervix, ovaries, fallopian tubes, uterus, vagina, and vulva. Although gynecologic cancers are characterized by different signs and symptoms, studies have shown that they share common risk factors, such as smoking, obesity, age, exposure to certain chemicals, infection with human immunodeficiency virus (HIV), and infection with human papilloma virus (HPV). Despite recent advancements in the preventative, diagnostic, and therapeutic interventions for gynecologic cancers, many patients still die as a result of metastasis and recurrence. Since mounting evidence indicates that the epithelial-mesenchymal transition (EMT) process plays an essential role in metastatic relapse of cancer, understanding the molecular aberrations responsible for the EMT and its underlying signaling should be given high priority in order to reduce cancer morbidity and mortality.

Overexpression of Notch1 is associated with the progression of cervical cancer

Cervical cancer is the third most common malignancy worldwide, accounting for 250,000 mortalities annually. Notch1, an important regulator of cell-fate decisions and differentiation, has been found to be overexpressed in certain types of cancer. However, the role of Notch1 in cervical carcinogenesis remains unclear. In the present study, immunohistochemical staining and western blot analysis revealed that Notch1 expression was significantly higher in cervical cancer tissues than that in normal cervical tissues. Furthermore, statistical analysis revealed that Notch1 expression was significantly associated with tumor differentiation and tumor stage. These findings indicated that Notch1 expression was associated with the progression of cervical cancer. The western blot assay also identified a positive correlation between Notch1 and Ki67 expression in cervical cancer tissues, which suggested that Notch1 expression may be associated with the proliferation of cervical cancer. In order to further evaluate the specific role of Notch1 in cervical cancer progression, its expression in SiHa and C33A cells was knocked down using small interfering RNA. It was revealed that the knockdown of Notch1 in SiHa and C33A cells resulted in significant inhibition of cell proliferation and colony formation in vitro. These results indicated that Notch1 was able to promote cell proliferation in cervical cancer. In conclusion, the results of the present study indicated that Notch1 may function as a promoter in cervical carcinogenesis.

RhoC mediates invasion and migration of CaSki cells through the Rho-associated serine-threonine protein kinase 1 signaling pathway

OBJECTIVE

The small GTPase RhoC in human cancers is up-regulated and correlated with tumor metastasis. However, the role of Rho/Rho-associated serine-threonine protein kinase 1 (ROCK1) signaling pathway in human cervical cancer is still unclear. In this study, we examine the effects of RhoC and its major downstream target, ROCK1, on the invasion and migration of CaSki cells to investigate the role of RhoC/ROCK1 signaling pathway in the progression of cervical squamous cell carcinoma.

METHODS

RhoC and ROCK1 protein expression in CaSki cells was detected by Western blotting. Scratch and transwell assays were carried out to assess the effects of RhoC on invasion and migration of CaSki cells. Cell viability was assayed by MTT test after adding the ROCK1 inhibitor Y-27632 to CaSki cells.

RESULTS

Overexpression of RhoC protein in CaSki cells significantly increases ROCK1 expression and promotes cell invasion and migration compared with the control group (P < 0.05). However, in the inhibition of ROCK1 with Y-27632 in CaSki cells when RhoC was overexpressed, the rate of invasiveness and migration was reduced remarkably (P < 0.05), dropping to comparable levels as the control.

CONCLUSIONS

This study suggested that the activation of RhoC/ROCK1 signaling pathways is likely involved in the progression of cervical squamous cell carcinoma.

The role of RhoC in epithelial-to-mesenchymal transition of ovarian carcinoma cells

Background

RhoC is a small G protein/GTPase and involved in tumor mobility, invasion and metastasis. Previously, up-regulated RhoC expression is found to play an important role in ovarian carcinogenesis and subsequent progression by modulating proliferation, apoptosis, migration and invasion.

Methods

We transfected RhoC-expressing plasmid and RhoC siRNA into CAOV3 and OVCAR3 cells respectively. These cells and transfectants were exposed to vascular epithelial growth factor (VEGF), transforming growth factor (TGF)-β1 or their receptor inhibitors with the phenotypes and their related-molecules examined.

Results

TGF-β1R or VEGFR inhibitor suppressed the proliferation, migration, invasion and lamellipodia formation, the expression of N-cadherin, α-SMA, snail and Notch1 mRNA or protein, and enhanced E-cadherin mRNA and protein expression in CAOV3 and its RhoC-overexpressing transfectants, whereas both growth factors had the opposite effects in OVCAR3 cells and their RhoC-hypoexpressing transfectants. Ectopic RhoC expression enhanced migration, invasion, lamellipodia formation and the alteration in epithelial to mesenchymal transition (EMT) markers of CAOV3 cells regardless of the treatment of VEGFR or TGF-β1R inhibitor, whereas RhoC knockdown resulted in the converse in OVCAR3 cells even with the exposure to VEGF or TGF-β1.

Conclusion

RhoC expression might be involved in EMT of ovarian epithelial carcinoma cells, stimulated by TGF-β1 and VEGF.

Transforming growth factor β1 signal is crucial for dedifferentiation of cancer cells to cancer stem cells in osteosarcoma

Human osteosarcoma harbors a small subpopulation of cancer stem cells (CSCs) that is believed to be associated with tumor metastasis, radioresistance/chemoresistance, local invasion, and poor clinical outcome. In this study, we found that transforming growth factor β1 (TGF-β1) signaling and a hypoxic environment dramatically induced self-renewal capacity in non-stem osteosarcoma cells, which in turn promoted chemoresistance, tumorigenicity, neovasculogenesis, and metastatic potential. Furthermore, blocking the TGF-β1 signaling pathway resulted in the inhibition of the dedifferentiation and clonogenicity of osteosarcoma cells, and the reduction of CSC self-renewal capacity and hypoxia-mediated dedifferentiation. These findings demonstrate that stem cells and non-stem cells exist in a dynamic equilibrium within the osteosarcoma cell population, and that CSCs may develop de novo from differentiated cancer cells. Hierarchical models of mammalian CSCs, therefore, should be considered to serve as bidirectional interconversion between the stem and non-stem cell components of the tumor.

RhoC interacts with integrin α5β1 and enhances its trafficking in migrating pancreatic carcinoma cells

Human pancreatic ductal adenocarcinoma (PDAC) is characterized by early systemic dissemination. Although RhoC has been implicated in cancer cell migration, the relevant underlying molecular mechanisms remain unknown. RhoC has been implicated in the enhancement of cancer cell migration and invasion, with actions which are distinct from RhoA (84% homology), and are possibly attributed to the divergent C-terminus domain. Here, we confirm that RhoC significantly enhances the migratory and invasive properties of pancreatic carcinoma cells. In addition, we show that RhoC over-expression decreases cancer cell adhesion and, in turn, accelerates cellular body movement and focal adhesion turnover, especially, on fibronectin-coated surfaces. Whilst RhoC over-expression did not alter integrin expression patterns, we show that it enhanced integrin α5β1 internalization and re-cycling (trafficking), an effect that was dependent specifically on the C-terminus (180-193 amino acids) of RhoC protein. We also report that RhoC and integrin α5β1 co-localize within the peri-nuclear region of pancreatic tumor cells, and by masking the CAAX motif at the C-terminal of RhoC protein, we were able to abolish this interaction in vitro and in vivo. Co-localization of integrin α5β1 and RhoC was demonstrable in invading cancer cells in 3D-organotypic cultures, and further mimicked in vivo analyses of, spontaneous human, (two distinct sources: operated patients and rapid autopsy programme) and transgenic murine (LSL-KrasG12D/+;LSL-Trp53R172H/+;Pdx-1-Cre), pancreatic cancers. In both cases, co-localization of integrin α5β1 and RhoC correlated with poor differentiation status and metastatic potential. We propose that RhoC facilitates tumor cell invasion and promotes subsequent metastasis, in part, by enhancing integrin α5β1 trafficking. Thus, RhoC may serve as a biomarker and a therapeutic target.

Physiological roles of Rho and Rho effectors in mammals

Rho GTPase is a master regulator controlling cytoskeleton in multiple contexts such as cell migration, adhesion and cytokinesis. Of several Rho GTPases in mammals, the best characterized is the Rho subfamily including ubiquitously expressed RhoA and its homologs RhoB and RhoC. Upon binding GTP, Rho exerts its functions through downstream Rho effectors, such as ROCK, mDia, Citron, PKN, Rhophilin and Rhotekin. Until recently, our knowledge about functions of Rho and Rho effectors came mostly from in vitro studies utilizing cultured cells, and their physiological roles in vivo were largely unknown. However, gene-targeting studies of Rho and its effectors have now unraveled their tissue- and cell-specific roles and provide deeper insight into the physiological function of Rho signaling in vivo. In this article, we briefly describe previous studies of the function of Rho and its effectors in vitro and then review and discuss recent studies on knockout mice of Rho and its effectors.

Cyclin D1, E-cadherin and beta-catenin expression in FIGO Stage IA cervical squamous carcinoma: diagnostic value and evidence for epithelial-mesenchymal transition

AIMS

Immunohistochemistry is helpful in distinguishing cervical neoplastic lesions from their histological mimics, but has contributed less towards the sometimes problematic distinction of in-situ and superficially invasive tumours. Epithelial-mesenchymal transition (EMT) may be a mechanism of invasion in cervical neoplasia and expression of EMT-associated proteins could prove useful in this diagnostic setting.

METHODS AND RESULTS

Immunohistochemical expression of cyclin D1, E-cadherin and beta-catenin was assessed in 22 biopsy specimens from FIGO Stage IA cervical squamous carcinomas, all of which also included foci of cervical intraepithelial neoplasia (CIN) 3, nine biopsies of CIN 3 adjacent to carcinoma, and 10 cases of CIN 3 only. Most invasive tumour cells expressed cyclin D1 and showed a reduction in E-cadherin and beta-catenin staining. Nuclear beta-catenin expression was not observed. Cyclin D1 staining was reduced or showed altered distribution in most cases of CIN 3, while adhesion protein expression generally was preserved. However, altered protein expression similar to that of invasion was seen in some CIN lesions.

CONCLUSIONS

Most superficially invasive cervical squamous carcinomas show immunophenotypical changes consistent with EMT. These alterations, particularly cyclin D1 expression, may be useful diagnostically. Similar changes in CIN 3 lesions may indicate the acquisition of increased invasive potential.

RHOC: a key gene for endometriosis

Considerable efforts have been invested in elucidating the potential mechanisms involved in the physiopathology of endometriosis. The aims of our study were to investigate whether RHOC expression is differentially altered in the endometrium and in endometriotic lesions. A total of 40 patients diagnosed with endometriosis and 15 healthy fertile women were selected for the study. Paired biopsies of endometrial tissue (eutopic endometrium) and endometriotic lesions (ectopic endometrium) were obtained from the patients with endometriosis. Endometrium from women without endometriosis was used as a control. Expression of the RHOC gene was analyzed by real-time polymerase chain reaction in autologous endometrial tissues of women with endometriosis and in the endometrium of control women. Increased RHOC expression was detected in endometriotic lesions compared to the eutopic endometrium of women with endometriosis and control women. RHOC changes may be among the key elements involved in the origin and the maintenance of endometriosis.

RhoC regulates the proliferation of gastric cancer cells through interaction with IQGAP1

Our previous research results showed that both Ras homolog family member C (RhoC) and IQ-domain GTPase-activating protein 1 (IQGAP1) were over-expressed in gastric cancer tissues and cells, but their role in tumorigenensis has not been addressed clearly. Herein we reported the proliferation stimulating effect of RhoC and IQGAP1 on gastric cancer cells and the interaction between two proteins in regulating the proliferation of gastric cancer cells. Plasmids and viral constructs encoding target siRNA and DNA were used to alter the expression of RhoC and IQGAP1. MTT method and BrdU incorporation assay were used for analyzing the effect of RhoC and different structures of IQGAP1 on proliferation. Protein levels of IQGAP1 and RhoC in cell lines were detected by Western blotting. Immunofluorescence and Co-Immunoprecipitation assays were applied to investigate the localization and binding between RhoC and IQGAP1. The results showed that RhoC, IQGAP1 and the C-terminal fragment of IQGAP1 significantly stimulated the proliferation of gastric cancer cells, and enhanced the expression of cyclin E and cyclin D1. By contrast, reduction of endogenous IQGAP1 or RhoC by siRNA attenuated cell proliferation. The depletion of IQGAP1 expression by siRNA significantly blocked the proliferative activity of constitutively active RhoC, while RhoC silencing by siRNA had no effect on IQGAP1-induced proliferation in gastric cancer cells. Co-immunoprecipitation and Immunofluorescence assays showed that RhoC and IQGAP1 bound each other. In conclusion, our results suggest that RhoC stimulates the proliferation of gastric cancer cells through recruiting IQGAP1 as an effector.

RhoC regulates the proliferation of gastric cancer cells through interaction with IQGAP1

Our previous research results showed that both Ras homolog family member C (RhoC) and IQ-domain GTPase-activating protein 1 (IQGAP1) were over-expressed in gastric cancer tissues and cells, but their role in tumorigenensis has not been addressed clearly. Herein we reported the proliferation stimulating effect of RhoC and IQGAP1 on gastric cancer cells and the interaction between two proteins in regulating the proliferation of gastric cancer cells. Plasmids and viral constructs encoding target siRNA and DNA were used to alter the expression of RhoC and IQGAP1. MTT method and BrdU incorporation assay were used for analyzing the effect of RhoC and different structures of IQGAP1 on proliferation. Protein levels of IQGAP1 and RhoC in cell lines were detected by Western blotting. Immunofluorescence and Co-Immunoprecipitation assays were applied to investigate the localization and binding between RhoC and IQGAP1. The results showed that RhoC, IQGAP1 and the C-terminal fragment of IQGAP1 significantly stimulated the proliferation of gastric cancer cells, and enhanced the expression of cyclin E and cyclin D1. By contrast, reduction of endogenous IQGAP1 or RhoC by siRNA attenuated cell proliferation. The depletion of IQGAP1 expression by siRNA significantly blocked the proliferative activity of constitutively active RhoC, while RhoC silencing by siRNA had no effect on IQGAP1-induced proliferation in gastric cancer cells. Co-immunoprecipitation and Immunofluorescence assays showed that RhoC and IQGAP1 bound each other. In conclusion, our results suggest that RhoC stimulates the proliferation of gastric cancer cells through recruiting IQGAP1 as an effector.

Human Breast Cancer Stem Cells Have Significantly Higher Rate of Clathrin-Independent and Caveolin-Independent Endocytosis than the Differentiated Breast Cancer Cells

Breast Cancer Stem (BCS) cells play critical roles in self-renewal, Multi Drug Resistance (MDR), differentiation and generation of secondary tumors. Conventional chemotherapy may efficiently kill the bulk of differentiated drug sensitive breast cancer cells, but not the MDR self-renewable BCS cells, leading to enrichment of the MDR BCS cells. In order to target the MDR BCS cells, we have isolated: 1) BCS cells from either breast cancer cell lines or fresh breast cancer specimens; 2) ATP binding cassette (ABC) transporter group G number 2 (ABCG2)-specific aptamers; and 3) BCS cell-binding aptamers. Interestingly, ABCG2-specific aptamers labeled the membrane surface of the ABCG2-expressing baby hamster kidney (BHK) cells, but stained whole cells of the BCS cells derived from mammospheres, implying that BCS cells might have much higher rate of endocytosis than the ABCG2-expressing BHK cells. In addition, 5D3, a monoclonal antibody that recognizes the extracellular loops of ABCG2 protein, also stained whole BCS cells. Furthermore, BCS cell-binding aptamers stained whole BCS cells, but not the differentiated breast cancer MCF-7 cells. All these results support above conclusion that BCS cells might have high rate of endocytosis. Further experiments performed with aptamers and human transferrin or lactosylceramide showed that BCS cells do have much higher endocytosis rate than the differentiated breast cancer cells. Interestingly, clathrin dependent endocytosis inhibitors, such as monodansylcadaverine or sucrose, or caveolin-dependent endocytosis inhibitors, such as methyl-β-cyclodextrin or genistein, can inhibit the internalization of transferrin or lactosylceramide into the differentiated breast cancer cells, but cannot block the internalization of these compounds into the BCS cells, suggesting that BCS cells undergo clathrin-independent and caveolin-independent endocytosis. Taken together, our data suggest that BCS cells have high rate of endocytosis and open the possibilities for delivering therapeutic agents directly into the MDR BCS cells with aptamer-coated liposomes.

Nuclear expression of Rac1 in cervical premalignant lesions and cervical cancer cells

Background

Abnormal expression of Rho-GTPases has been reported in several human cancers. However, the expression of these proteins in cervical cancer has been poorly investigated. In this study we analyzed the expression of the GTPases Rac1, RhoA, Cdc42, and the Rho-GEFs, Tiam1 and beta-Pix, in cervical pre-malignant lesions and cervical cancer cell lines.

Methods

Protein expression was analyzed by immunochemistry on 102 cervical paraffin-embedded biopsies: 20 without Squamous Intraepithelial Lesions (SIL), 51 Low- grade SIL, and 31 High-grade SIL; and in cervical cancer cell lines C33A and SiHa, and non-tumorigenic HaCat cells. Nuclear localization of Rac1 in HaCat, C33A and SiHa cells was assessed by cellular fractionation and Western blotting, in the presence or not of a chemical Rac1 inhibitor (NSC23766).

Results

Immunoreacivity for Rac1, RhoA, Tiam1 and beta-Pix was stronger in L-SIL and H-SIL, compared to samples without SIL, and it was significantly associated with the histological diagnosis. Nuclear expression of Rac1 was observed in 52.9% L-SIL and 48.4% H-SIL, but not in samples without SIL. Rac1 was found in the nucleus of C33A and SiHa cells but not in HaCat cells. Chemical inhibition of Rac1 resulted in reduced cell proliferation in HaCat, C33A and SiHa cells.

Conclusion

Rac1 is expressed in the nucleus of epithelial cells in SILs and cervical cancer cell lines, and chemical inhibition of Rac1 reduces cellular proliferation. Further studies are needed to better understand the role of Rho-GTPases in cervical cancer progression.

Notch1-mediated tumor suppression in cervical cancer with the involvement of SST signaling and its application in enhanced SSTR-targeted therapeutics

The role of Notch signaling in cervical cancer is seemingly controversial. To confirm the function of Notch signaling in this type of cancer, we established a stable Notch1-activated cervical cancer HeLa cell line. We found that Notch1 activation resulted in apoptosis, cell cycle arrest, and tumor suppression. At the molecular level, we found that a variety of genes associated with cyclic AMP, G protein-coupled receptor, and cancer signaling pathways contributed to Notch1-mediated tumor suppression. We observed that the expression of somatostatin (SST) was dramatically induced by Notch1 signaling activation, which was accompanied by enhanced expression of the cognate SST receptor subtype 1 (SSTR1) and SSTR2. Certain genes, such as tumor protein 63 (TP63, p63), were upregulated, whereas others, such as B-cell lymphoma 2 (BCL-2), Myc, Akt, and STAT3, were downregulated. Subsequently, knockdown of Notch1-induced SST reversed Notch1-induced decrease of BCL-2 and increase of p63, indicating that Notch1-induced tumor suppression may be partly through upregulating SST signaling. Our findings support a possible crosstalk between Notch signaling and SST signaling. Moreover, Notch-induced SSTR activation could enhance SSTR-targeted cancer chemotherapy. Valproic acid (VPA), a histone deacetylase inhibitor, suppressed cell growth and upregulated the expression of Notch1 and SSTR2. A combination therapy with VPA and the SSTR2-targeting cytotoxic conjugate CPT-SST strongly led to greater suppression, as compared to each alone. Our findings thus provide us with a promising clinical opportunity for enhanced cancer therapy using combinations of Notch1-activating agents and SSTR2-targeting agents.

Epithelial-mesenchymal transition in cervical carcinoma

During the progression of epithelial cancer, cells usually lose epithelial characteristic features and gain a mesenchymal phenotype. Cervical cancer is a common female malignancy worldwide. Despite the generally good prognosis for early-stage cervical cancer patients, many patients still die as a result of metastasis and recurrence. Epithelial-mesenchymal transition (EMT) has been implicated in the metastasis of primary tumors and provides molecular mechanisms for cervical cancer metastasis. Here we provide an up-to-date overview regarding the program of EMT in cervical cancer. In the stepwise progression of cervical cancer, human papilloma viral proteins contribute to the cell transformation and the conversion of typical epithelial cells to the epithelial carcinoma cells with hybrid epithelial and mesenchymal characteristics. Molecules related to the EMT program of cervical cancer cells are summarized in this review paper. Several soluble factors acting on their cognate receptors stimulate the mesenchymal transition of cervical epithelial cells. Ion transport system as well as cytoskeletal modulators also stimulate the progression of EMT program in cervical carcinoma cells. Transcriptional factors such as Snail, Twist1, Twist2, and six1 homeoproteins are involved in the complicated regulation and cervical cancer metastasis. Among the various signalings associated with EMT program, Snail is a central transcription factor which governs EMT program. In contrast to tumor promoters, several tumor suppressors such as SFRP1/2 and LMX-1A have been reported to suppress tumorigenesis as well as metastatic spread through inhibiting the EMT program.

Notch signaling in CD66+ cells drives the progression of human cervical cancers

Human epithelial tumor progression and metastasis involve cellular invasion, dissemination in the vasculature, and regrowth at metastatic sites. Notch signaling has been implicated in metastatic progression but its roles have yet to be fully understood. Here we report the important role of Notch signaling in maintaining cells expressing the carcinoembryonic antigen cell adhesion molecule CEACAM (CD66), a known mediator of metastasis. CD66 and Notch1 were studied in clinical specimens and explants of human cervical cancer, including specimens grown in a pathophysiologically relevant murine model. Gene expression profiling of CD66(+) cells from primary tumors showed enhanced features of Notch signaling, metastasis, and stemness. Significant differences were also seen in invasion, colony formation, and tumor forming efficiency between CD66(+) and CD66(-) cancer cells. Notably, CD66(+) cells showed a marked sensitivity to a Notch small molecule inhibitor. In support of studies in established cell lines, we documented the emergence of a tumorigenic CD66(+) cell subset within a metastatic lesion-derived cervical-cancer cell line. Similar to primary cancers, CD66 expression in the cell line was blocked by chemical and genetic inhibitors of ligand-dependent nuclear Notch signaling. Collectively, our work on the oncogenic properties of CD66(+) cells in epithelial cancers provides insights into the nature of tumor progression and offers a mechanistic rationale to inhibit the Notch signaling pathway as a generalized therapeutic strategy to treat metastatic cancers.

Identification of differential expressed transcripts in cervical cancer of Mexican patients

The aim of this study was to identify the gene expression profile in biopsies of patients with cervical intraepithelial neoplasia (CIN) 1, CIN 2, CIN 3, and microinvasive cancer by suppression subtractive hybridization and Southern blotting. After analyzing 1,800 cDNA clones, we found 198 upregulated genes, 166 downregulated, and no significant change of gene expression in 86 clones (p = 0.005). These results were validated by Northern blot analysis (p = 0.0001) in the identification of 28 overexpressed and 7 downregulated transcripts. We observed a set of genes related to the Notch signaling pathway that may be involved in the transformation of cervical cells and in the development to malignancy. The differentially expressed genes may provide useful information about the molecular mechanisms involved in human cervical carcinoma and as diagnostic markers.

Integrin-linked kinase 1: role in hormonal cancer progression

Integrin-linked kinase 1 (ILK1) is a serine/threonine kinase that plays important roles in a variety of cellular functions including cell survival, migration and angiogenesis. ILK1 is normally expressed in numerous tissues and activated by growth factors, cytokines and hormones. Dysregulation of ILK1 expression or function is found in several hormonal tumors including breast, ovary and prostate. Emerging evidence suggests that ILK overexpression promotes cellular transformation, cell survival, epithelial mesenchymal transition (EMT), and metastasis of hormonal cancer cells while inhibition of ILK1 reduces tumor growth and progression. The recent development of ILK1 inhibitors has provided novel mechanisms for blocking ILK1 signaling to curb metastasis and therapy resistance of hormonal tumors. This review will focus on recent advances made towards understanding the role of ILK signaling axis in progression of hormonal cancer.

Role of Notch and its oncogenic signaling crosstalk in breast cancer

The Notch signaling plays a key role in cell differentiation, survival, and proliferation through diverse mechanisms. Notch signaling is also involved in vasculogenesis and angiogenesis. Moreover, Notch expression is regulated by hypoxia and inflammatory cytokines (IL-1, IL-6 and leptin). Entangled crosstalk between Notch and other developmental signaling (Hedgehog and Wnt), and signaling triggered by growth factors, estrogens and oncogenic kinases, could impact on Notch targeted genes. Thus, alterations of the Notch signaling can lead to a variety of disorders, including human malignancies. Notch signaling is activated by ligand binding, followed by ADAM/tumor necrosis factor-α-converting enzyme (TACE) metalloprotease and γ-secretase cleavages that produce the Notch intracellular domain (NICD). Translocation of NICD into the nucleus induces the transcriptional activation of Notch target genes. The relationships between Notch deregulated signaling, cancer stem cells and the carcinogenesis process reinforced by Notch crosstalk with many oncogenic signaling pathways suggest that Notch signaling may be a critical drug target for breast and other cancers. Since current status of knowledge in this field changes quickly, our insight should be continuously revised. In this review, we will focus on recent advancements in identification of aberrant Notch signaling in breast cancer and the possible underlying mechanisms, including potential role of Notch in breast cancer stem cells, tumor angiogenesis, as well as its crosstalk with other oncogenic signaling pathways in breast cancer. We will also discuss the prognostic value of Notch proteins and therapeutic potential of targeting Notch signaling for cancer treatment.