Suppression of breast cancer metastasis through the inactivation of ADP-ribosylation factor 1

Deciphering Proteoform Landscape of Mammary Carcinoma by Top-Down Proteomics

Defining the proteoform landscape of breast cancer can provide unique insights into the signaling pathways driving disease progression. While bottom-up proteomics has been utilized to profile breast cancer, it lacks the ability to capture intact proteoforms that may underpin the disease. Top-down proteomics is ideally suited to characterize intact proteoforms; however, most top-down proteomics studies have been limited to low molecular weight (MW) proteins (<50 kDa). Herein, we employed a two-dimensional (2D) liquid chromatography combining size exclusion chromatography (SEC) with reverse phase chromatography (RPC) followed by high-resolution mass spectrometry (MS) to expand the coverage for high MW proteoforms. Using this 2D-SEC-RPC-MS approach, we observed a 5-fold increase in the detection of high MW proteoforms (>50 kDa) compared to the conventional 1D-RPC-MS. SEC separation significantly enhanced the detection of high MW proteoforms (>104 kDa), including intermediate filament proteins, vimentin and keratins. Based on accurate mass measurements and MS/MS data, we identified 775 proteoforms from both TFA and HEPES extracts and detected PTMs, such as acetylation, glutathionylation, and myristoylation. Pathway analysis uncovered many proteoforms involved in processes dysregulated in cancer progression. Overall, our findings illustrate the power of top-down proteomics in defining the proteoform landscape of breast carcinoma.

Golgiphagy: a novel selective autophagy to the fore

The Golgi apparatus is the central hub of the cellular endocrine pathway and plays a crucial role in processing, transporting, and sorting proteins and lipids. Simultaneously, it is a highly dynamic organelle susceptible to degradation or fragmentation under various physiological or pathological conditions, potentially contributing to the development of numerous human diseases. Autophagy serves as a vital pathway for eukaryotes to manage intracellular and extracellular stress and maintain homeostasis by targeting damaged or redundant organelles for removal. Recent research has revealed that autophagy mechanisms can specifically degrade Golgi components, known as Golgiphagy. This review summarizes recent findings on Golgiphagy while also addressing unanswered questions regarding its mechanisms and regulation, aiming to advance our understanding of the role of Golgiphagy in human disease.

Novel Arf1 Inhibitors Drive Cancer Stem Cell Aging and Potentiate Anti-Tumor Immunity

The small G protein Arf1 has been identified as playing a selective role in supporting cancer stem cells (CSCs), making it an attractive target for cancer therapy. However, the current Arf1 inhibitors have limited translational potential due to their high toxicity and low specificity. In this study, two new potent small-molecule inhibitors of Arf1, identified as DU101 and DU102, for cancer therapy are introduced. Preclinical tumor models demonstrate that these inhibitors triggered a cascade of aging in CSCs and enhance anti-tumor immunity in mouse cancer and PDX models. Through single-cell sequencing, the remodeling of the tumor immune microenvironment induced by these new Arf1 inhibitors is analyzed and an increase in tumor-associated CD8+ CD4+ double-positive T (DPT) cells is identified. These DPT cells exhibit superior features of active CD8 single-positive T cells and a higher percentage of TCF1+PD-1+, characteristic of stem-like T cells. The frequency of tumor-infiltrating stem-like DPT cells correlates with better disease-free survival (DFS) in cancer patients, indicating that these inhibitors may offer a novel cancer immunotherapy strategy by converting the cold tumor immune microenvironment into a hot one, thus expanding the potential for immunotherapy in cancer patients.

Pan-cancer analysis of ARFs family and ARF5 promoted the progression of hepatocellular carcinoma

Background

ARF family proteins are a kind of small GTPases, which are involved in regulating a variety of basic functions of cells. In recent years, the role and molecular regulatory mechanisms of ARFs in tumor progression have received increasing attention, and research reports on most of their family members are increasing. However, research on the clinical and pathological relevance of ARF5 in cancer, especially in hepatocellular carcinoma, still needs to be improved.

Methods

RNA-seq data in the Cancer Genome Atlas (TCGA) and genome tissue expression (GTEx) databases were used to analyze the expression and pathological data of ARFs family in Pan-cancer. Kaplan-Meier and Cox regression were used for prognostic analysis of ARF5 and Pan-cancer. Combined with ImmuCellAI database and TIMER2 database, the relationship between ARF5 expression and immune cell tumor infiltration in hepatocellular carcinoma (HCC) was analyzed. WGCNA is used to construct the co-expression gene network related to ARF5 expression in HCC and screen important modules and central genes. GO and KEGG path enrichment analysis were carried out for the genes in the modules with clinical significance. GSEA analysis was performed to take into account the role of genes with small differences. Finally, ceRNA network analysis was used to explore the molecular mechanism of miRNAs and lncRNAs regulating ARF5 expression.

Results

ARFs family (ARF1, ARF3, ARF4, ARF5, ARF6) are generally highly expressed in Pan-cancer. ARF5 is significantly highly expressed in 29 cancers, and the high expression of ARF5 in HCC patients is significantly negatively correlated with OS, DFI, PFI and DSS, which may lead to cancer deterioration by participating in tumor immune infiltration of HCC. Through WGCNA analysis, the expression of ARF5 in HCC may be involved in many cellular processes that consume a lot of energy, such as ribosome formation, RNA and protein synthesis and lipids, as well as COVID-19, nonalcoholic fatty liver, neurodegenerative diseases and other disease pathways.

Conclusion

ARFs, especially ARF5, are overexpressed in many human tumors. This study shows for the first time that ARF5 is significantly correlated with the poor prognosis of HCC patients, which may play a role as an oncogene, suggesting that ARF5 has the potential as a biomarker for the diagnosis and treatment of HCC.

Membrane trafficking alterations in breast cancer progression

Breast cancer (BC) is the most common type of cancer in women, and remains one of the major causes of death in women worldwide. It is now well established that alterations in membrane trafficking are implicated in BC progression. Indeed, membrane trafficking pathways regulate BC cell proliferation, migration, invasion, and metastasis. The 22 members of the ADP-ribosylation factor (ARF) and the >60 members of the rat sarcoma (RAS)-related in brain (RAB) families of small GTP-binding proteins (GTPases), which belong to the RAS superfamily, are master regulators of membrane trafficking pathways. ARF-like (ARL) subfamily members are involved in various processes, including vesicle budding and cargo selection. Moreover, ARFs regulate cytoskeleton organization and signal transduction. RABs are key regulators of all steps of membrane trafficking. Interestingly, the activity and/or expression of some of these proteins is found dysregulated in BC. Here, we review how the processes regulated by ARFs and RABs are subverted in BC, including secretion/exocytosis, endocytosis/recycling, autophagy/lysosome trafficking, cytoskeleton dynamics, integrin-mediated signaling, among others. Thus, we provide a comprehensive overview of the roles played by ARF and RAB family members, as well as their regulators in BC progression, aiming to lay the foundation for future research in this field. This research should focus on further dissecting the molecular mechanisms regulated by ARFs and RABs that are subverted in BC, and exploring their use as therapeutic targets or prognostic markers.

Targeting small GTPases: emerging grasps on previously untamable targets, pioneered by KRAS

Small GTPases including Ras, Rho, Rab, Arf, and Ran are omnipresent molecular switches in regulating key cellular functions. Their dysregulation is a therapeutic target for tumors, neurodegeneration, cardiomyopathies, and infection. However, small GTPases have been historically recognized as "undruggable". Targeting KRAS, one of the most frequently mutated oncogenes, has only come into reality in the last decade due to the development of breakthrough strategies such as fragment-based screening, covalent ligands, macromolecule inhibitors, and PROTACs. Two KRAS^G12C covalent inhibitors have obtained accelerated approval for treating KRAS^G12C mutant lung cancer, and allele-specific hotspot mutations on G12D/S/R have been demonstrated as viable targets. New methods of targeting KRAS are quickly evolving, including transcription, immunogenic neoepitopes, and combinatory targeting with immunotherapy. Nevertheless, the vast majority of small GTPases and hotspot mutations remain elusive, and clinical resistance to G12C inhibitors poses new challenges. In this article, we summarize diversified biological functions, shared structural properties, and complex regulatory mechanisms of small GTPases and their relationships with human diseases. Furthermore, we review the status of drug discovery for targeting small GTPases and the most recent strategic progress focused on targeting KRAS. The discovery of new regulatory mechanisms and development of targeting approaches will together promote drug discovery for small GTPases.

The small GTPase ARF3 controls invasion modality and metastasis by regulating N-cadherin levels

ARF GTPases are central regulators of membrane trafficking that control local membrane identity and remodeling facilitating vesicle formation. Unraveling their function is complicated by the overlapping association of ARFs with guanine nucleotide exchange factors (GEFs), GTPase-activating proteins (GAPs), and numerous interactors. Through a functional genomic screen of three-dimensional (3D) prostate cancer cell behavior, we explore the contribution of ARF GTPases, GEFs, GAPs, and interactors to collective invasion. This revealed that ARF3 GTPase regulates the modality of invasion, acting as a switch between leader cell-led chains of invasion or collective sheet movement. Functionally, the ability of ARF3 to control invasion modality is dependent on association and subsequent control of turnover of N-cadherin. In vivo, ARF3 levels acted as a rheostat for metastasis from intraprostatic tumor transplants and ARF3/N-cadherin expression can be used to identify prostate cancer patients with metastatic, poor-outcome disease. Our analysis defines a unique function for the ARF3 GTPase in controlling how cells collectively organize during invasion and metastasis.

GTPase Pathways in Health and Diseases

GTPases, the molecular switches toggling between an inactive GDP-bound state and an active GTP-bound state, play a pivotal role in controlling complex cellular processes (e [...].

Dance of The Golgi: Understanding Golgi Dynamics in Cancer Metastasis

The Golgi apparatus is at the center of protein processing and trafficking in normal cells. Under pathological conditions, such as in cancer, aberrant Golgi dynamics alter the tumor microenvironment and the immune landscape, which enhances the invasive and metastatic potential of cancer cells. Among these changes in the Golgi in cancer include altered Golgi orientation and morphology that contribute to atypical Golgi function in protein trafficking, post-translational modification, and exocytosis. Golgi-associated gene mutations are ubiquitous across most cancers and are responsible for modifying Golgi function to become pro-metastatic. The pharmacological targeting of the Golgi or its associated genes has been difficult in the clinic; thus, studying the Golgi and its role in cancer is critical to developing novel therapeutic agents that limit cancer progression and metastasis. In this review, we aim to discuss how disrupted Golgi function in cancer cells promotes invasion and metastasis.

Role of the Mosaic Cisternal Maturation Machinery in Glycan Synthesis and Oncogenesis

Tumorigenesis is associated with the deregulation of multiple processes, among which the glycosylation of lipids and proteins is one of the most extensively affected. However, in most cases, it remains unclear whether aberrant glycosylation is a cause, a link in the pathogenetic chain, or a mere consequence of tumorigenesis. In other cases, instead, studies have shown that aberrant glycans can promote oncogenesis. To comprehend how aberrant glycans are generated it is necessary to clarify the underlying mechanisms of glycan synthesis at the Golgi apparatus, which are still poorly understood. Important factors that determine the glycosylation potential of the Golgi apparatus are the levels and intra-Golgi localization of the glycosylation enzymes. These factors are regulated by the process of cisternal maturation which transports the cargoes through the Golgi apparatus while retaining the glycosylation enzymes in the organelle. This mechanism has till now been considered a single, house-keeping and constitutive function. Instead, we here propose that it is a mosaic of pathways, each controlling specific set of functionally related glycosylation enzymes. This changes the conception of cisternal maturation from a constitutive to a highly regulated function. In this new light, we discuss potential new groups oncogenes among the cisternal maturation machinery that can contribute to aberrant glycosylation observed in cancer cells. Further, we also discuss the prospects of novel anticancer treatments targeting the intra-Golgi trafficking process, particularly the cisternal maturation mechanism, to control/inhibit the production of pro-tumorigenic glycans.

Integrated In Silico Analyses Identify PUF60 and SF3A3 as New Spliceosome-Related Breast Cancer RNA-Binding Proteins

More women are diagnosed with breast cancer (BC) than any other type of cancer. Although large-scale efforts have completely redefined cancer, a cure remains unattainable. In that respect, new molecular functions of the cell should be investigated, such as post-transcriptional regulation. RNA-binding proteins (RBPs) are emerging as critical post-transcriptional modulators of tumorigenesis, but only a few have clear roles in BC. To recognize new putative breast cancer RNA-binding proteins, we performed integrated in silico analyses of all human RBPs (n = 1392) in three major cancer databases and identified five putative BC RBPs (PUF60, TFRC, KPNB1, NSF, and SF3A3), which showed robust oncogenic features related to their genomic alterations, immunohistochemical changes, high interconnectivity with cancer driver genes (CDGs), and tumor vulnerabilities. Interestingly, some of these RBPs have never been studied in BC, but their oncogenic functions have been described in other cancer types. Subsequent analyses revealed PUF60 and SF3A3 as central elements of a spliceosome-related cluster involving RBPs and CDGs. Further research should focus on the mechanisms by which these proteins could promote breast tumorigenesis, with the potential to reveal new therapeutic pathways along with novel drug-development strategies.

Construction and Analysis of the Dysregulated ceRNA Network and Identification of Risk Long Noncoding RNAs in Breast Cancer

Breast cancer (BRCA) is the second leading cause of cancer-related mortality in women worldwide. However, the molecular mechanism involved in the development of BRCA is not fully understood. In this study, based on the miRNA-mediated long non-coding RNA (lncRNA)-protein coding gene (PCG) relationship and lncRNA-PCG co-expression information, we constructed and analyzed a specific dysregulated lncRNA-PCG co-expression network in BRCA. Then, we performed the random walk with restart (RWR) method to prioritize BRCA-related lncRNAs through comparing their RWR score and significance. As a result, we identified 30 risk lncRNAs for BRCA, which can distinguish normal and tumor samples. Moreover, through gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis, we found that these risk lncRNAs mainly synergistically exerted functions related to cell cycle and DNA separation and replication. At last, we developed a four-lncRNA prognostic signature (including AP000851.1, LINC01977, MAFG-DT, SIAH2-AS1) and assessed the survival accuracy of the signature by performing time-dependent receiver operating characteristic (ROC) analysis. The areas under the ROC curve for 1, 3, 5, and 10 years of survival prediction were 0.68, 0.61, 0.62, and 0.63, respectively. The multivariable Cox regression results verified that the four-lncRNA signature could be used as an independent prognostic biomarker in BRCA. In summary, these results have important reference value for the study of diagnosis, treatment, and prognosis evaluation of BRCA.

Zebrafish Avatar to Develop Precision Breast Cancer Therapies

BACKGROUND

Zebrafish (Danio rerio) is a vertebrate that has become a popular alternative model for the cellular and molecular study of human tumors and for drug testing and validating approaches. Notably, zebrafish embryos, thanks to their accessibility, allow rapid collection of in vivo results prodromal to validation in the murine models in respect to the 3R principles. The generation of tumor xenograft in zebrafish embryos and larvae, or zebrafish avatar, represents a unique opportunity to study tumor growth, angiogenesis, cell invasion and metastatic dissemination, interaction between tumor and host in vivo avoiding immunogenic rejection, representing a promising platform for the translational research and personalized therapies.

OBJECTIVE

In this mini-review we report recent advances in breast cancer research and drug testing that took advantage of the zebrafish xenograft model using both breast cancer cell lines and patient's biopsy.

CONCLUSION

Patient derived xenograft, together with the gene editing, the omics biotechnology, the in vivo time lapse imaging and the high-throughput screening that are already set up and largely used in zebrafish, could represent a step forward towards precision and personalized medicine in the breast cancer research field.

Subversion of Ras Small GTPases in Cutaneous Melanoma Aggressiveness

The rising incidence and mortality rate associated with the metastatic ability of cutaneous melanoma represent a major public health concern. Cutaneous melanoma is one of the most invasive human cancers, but the molecular mechanisms are poorly understood. Moreover, currently available therapies are not efficient in avoiding melanoma lethality. In this context, new biomarkers of prognosis, metastasis, and response to therapy are necessary to better predict the disease outcome. Additionally, the knowledge about the molecular alterations and dysregulated pathways involved in melanoma metastasis may provide new therapeutic targets. Members of the Ras superfamily of small GTPases regulate various essential cellular activities, from signaling to membrane traffic and cytoskeleton dynamics. Therefore, it is not surprising that they are differentially expressed, and their functions subverted in several types of cancer, including melanoma. Indeed, Ras small GTPases were found to regulate melanoma progression and invasion. Hence, a better understanding of the mechanisms regulated by Ras small GTPases that are involved in melanoma tumorigenesis and progression may provide new therapeutic strategies to block these processes. Here, we review the current knowledge on the role of Ras small GTPases in melanoma aggressiveness and the molecular mechanisms involved. Furthermore, we summarize the known involvement of these proteins in melanoma metastasis and how these players influence the response to therapy.

Analysis of circulating breast cancer cell heterogeneity and interactions with peripheral blood mononuclear cells

For solid tumors, extravasation of cancer cells and their survival in circulation represents a critical stage of the metastatic process that lacks complete understanding. Gaining insight into interactions between circulating tumor cells (CTCs) and other peripheral blood mononuclear cells (PBMCs) may provide valuable prognostic information. The purpose of this study was to use single-cell RNA-sequencing (scRNA-seq) of liquid biopsies from breast cancer patients to begin defining intravascular interactions. We captured CTCs from the peripheral blood of breast cancer patients using size-exclusion membranes followed by scRNA-seq of enriched CTCs and carry-over PBMCs. Transcriptome analysis identified two populations of CTCs: one enriched for transcripts indicative of estrogen responsiveness and increased proliferation and another enriched for transcripts characteristic of reduced proliferation and epithelial-mesenchymal transition (EMT). We applied interactome and pathway analysis to determine interactions between CTCs and other captured cells. Our analysis predicted for enhanced immune evasion in the CTC population with EMT characteristics. In addition, PD-1/PD-L1 pathway activation and T cell exhaustion were predicted in T cells isolated from breast cancer patients compared with normal T cells. We conclude that scRNA-seq of breast cancer CTCs generally stratifies them into two types based on their proliferative and epithelial state and differential potential to interact with PBMCs. Better understanding of CTC subtypes and their intravascular interactions may help design treatments directed against CTCs with high metastatic and immune-evasive competence.

Regulating the regulators: role of phosphorylation in modulating the function of the GBF1/BIG family of Sec7 ARF-GEFs

Membrane traffic between secretory and endosomal compartments is vesicle-mediated and must be tightly balanced to maintain a physiological compartment size. Vesicle formation is initiated by guanine nucleotide exchange factors (GEFs) that activate the ARF family of small GTPases. Regulatory mechanisms, including reversible phosphorylation, allow ARF-GEFs to support vesicle formation only at the right time and place in response to cellular needs. Here, we review current knowledge of how the Golgi-specific brefeldin A-resistance factor 1 (GBF1)/brefeldin A-inhibited guanine nucleotide exchange protein (BIG) family of ARF-GEFs is influenced by phosphorylation and use predictive paradigms to propose new regulatory paradigms. We describe a conserved cluster of phosphorylation sites within the N-terminal domains of the GBF1/BIG ARF-GEFs and suggest that these sites may respond to homeostatic signals related to cell growth and division. In the C-terminal region, GBF1 shows phosphorylation sites clustered differently as compared with the similar configuration found in both BIG1 and BIG2. Despite this similarity, BIG1 and BIG2 phosphorylation patterns are divergent in other domains. The different clustering of phosphorylation sites suggests that the nonconserved sites may represent distinct regulatory nodes and specify the function of GBF1, BIG1, and BIG2.

The Role of ARF Family Proteins and Their Regulators and Effectors in Cancer Progression: A Therapeutic Perspective

The Adenosine diphosphate-Ribosylation Factor (ARF) family belongs to the RAS superfamily of small GTPases and is involved in a wide variety of physiological processes, such as cell proliferation, motility and differentiation by regulating membrane traffic and associating with the cytoskeleton. Like other members of the RAS superfamily, ARF family proteins are activated by Guanine nucleotide Exchange Factors (GEFs) and inactivated by GTPase-Activating Proteins (GAPs). When active, they bind effectors, which mediate downstream functions. Several studies have reported that cancer cells are able to subvert membrane traffic regulators to enhance migration and invasion. Indeed, members of the ARF family, including ARF-Like (ARL) proteins have been implicated in tumorigenesis and progression of several types of cancer. Here, we review the role of ARF family members, their GEFs/GAPs and effectors in tumorigenesis and cancer progression, highlighting the ones that can have a pro-oncogenic behavior or function as tumor suppressors. Moreover, we propose possible mechanisms and approaches to target these proteins, toward the development of novel therapeutic strategies to impair tumor progression.

Design and Synthesis of Arf1-Targeting γ-Dipeptides as Potential Agents against Head and Neck Squamous Cell Carcinoma

Background: Head and neck squamous cell carcinoma (HNSCC) is one of the leading causes of cancer-related deaths and calls for new druggable targets. We have previously highlighted the critical role of ADP-ribosylation factor-1 (Arf1) activation in HNSCC. In the present study, we address the question whether targeting Arf1 could be proposed as a valuable strategy against HNSCC. Methods: We rationally designed and synthesized constrained ATC-based (4-amino-(methyl)-1,3-thiazole-5-carboxylic acid) γ-dipeptides to block Arf1 activation. We evaluated the effects of these γ-dipeptides in HNSCC cells: The cell viability was determined in 2D and 3D cell cultures after 72 h treatment and Arf1 protein levels and activity were assessed by GGA3 pull-down and Western blotting assays. Results: Targeting Arf1 offers a valuable strategy to counter HNSCC. Our new Arf1-targeting compounds revealed a strong in vitro cytotoxicity against HNSCC cells, through inhibiting Arf1 activation and its downstream pathways. Conclusions: Arf1-targeting γ-dipeptides developed in this study may represent a promising targeted therapeutic to improve managing the HNSCC disease.

Rho GTPases and related signaling complexes in cell migration and invasion

Cell migration and invasion play an important role in the development of cancer. Cell migration is associated with several specific actin filament-based structures, including lamellipodia, filopodia, invadopodia and blebs, and with cell-cell adhesion, cell-extracellular matrix adhesion. Migration occurs via different modes, human epithelial cancer cells mainly migrate collectively, while in vivo imaging studies in laboratory animals have found that most cells migrate as single cells. Rho GTPases play an important role in the process of cell migration, and several Rho GTPase-related signaling complexes are also involved. However, the exact mechanism by which these signaling complexes act remains unclear. This paper reviews how Rho GTPases and related signaling complexes interact with other proteins, how their expression is regulated, how tumor microenvironment-related factors play a role in invasion and metastasis, and the mechanism of these complex signaling networks in cell migration and invasion.

Drugging the Small GTPase Pathways in Cancer Treatment: Promises and Challenges

Small GTPases are a family of low molecular weight GTP-hydrolyzing enzymes that cycle between an inactive state when bound to GDP and an active state when associated to GTP. Small GTPases regulate key cellular processes (e.g., cell differentiation, proliferation, and motility) as well as subcellular events (e.g., vesicle trafficking), making them key participants in a great array of pathophysiological processes. Indeed, the dysfunction and deregulation of certain small GTPases, such as the members of the Ras and Arf subfamilies, have been related with the promotion and progression of cancer. Therefore, the development of inhibitors that target dysfunctional small GTPases could represent a potential therapeutic strategy for cancer treatment. This review covers the basic biochemical mechanisms and the diverse functions of small GTPases in cancer. We also discuss the strategies and challenges of inhibiting the activity of these enzymes and delve into new approaches that offer opportunities to target them in cancer therapy.

FGF19 amplification reveals an oncogenic dependency upon autocrine FGF19/FGFR4 signaling in head and neck squamous cell carcinoma

The fibroblast growth factor 19 gene FGF19 has previously been reported to be amplified in several cancer types and encodes for a key autocrine signaler known to promote tumorigenic growth. Thus, it is imperative to understand which cancers are oncogenically addicted to FGF19 amplification as well as the role it serves in these cancer types. We report for the first time high FGF19 amplification in head and neck squamous cell carcinomas (HNSCC), which is associated with increased autocrine secretion of FGF19 and poor patient outcome in HNSCC. FGF19 amplification corresponded with constitutive activation of FGF receptor 4 (FGFR4)-dependent ERK/AKT-p70S6K-S6 signaling activation in HNSCC cells, and addition of human recombinant FGF19 could promote cell proliferation and soft agar colony formation in HNSCC cells with low FGF19 expression through activation of FGFR4 and downstream signaling cascades. In contrast, FGF19 knockout counteracts the observed effects in HNSCC cells carrying high endogenous FGF19, with knockout of FGF19 significantly suppressing tumor growth in an orthotopic mouse model of HNSCC. Collectively, this study demonstrates that FGF19 gene amplification corresponds with an increased dependency upon FGF19/FGFR4 autocrine signaling in HNSCC, revealing a therapeutic target for this cancer type.

Histone deacetylase inhibitors suppress aggressiveness of head and neck squamous cell carcinoma via histone acetylation-independent blockade of the EGFR-Arf1 axis

BACKGROUND

A promising arsenal of histone deacetylase (HDAC)-targeted treatment has emerged in the past decade, as the abnormal targeting or retention of HDACs to DNA regulatory regions often occurs in many cancers. Head and neck squamous cell carcinoma (HNSCC) is one of the most aggressive malignancies worldwide associated with poor overall survival in late-stage patients. HDAC inhibitors have great potential to treat this devastating disease; however, few has been studied regarding the beneficial role of HDAC inhibition in anti-HNSCC therapy and the underlying molecular mechanisms remain elusive.

METHODS

Cell migration and invasion were examined by wound closure and Transwell assays. Protein levels and interactions were assessed by Western blotting and immunoprecipitation. HDAC activity was measured with the fluorometric HDAC Activity Assay. Phospho-receptor tyrosine kinase (RTK) profiling was determined by the Proteome Profiler Human Phospho-RTK Array.

RESULTS

ADP-ribosylation factor 1 (Arf1), a small GTPase coordinating vesicle-mediated intracellular trafficking, can be inactivated by HDAC inhibitors through histone acetylation-independent degradation of epidermal growth factor receptor (EGFR) in HNSCC cells. Mechanistically, high levels of Arf1 activity are maintained by binding to phosphorylated EGFR which is localized on HNSCC cell plasma membrane. Decreased EGFR phosphorylation is associated with reduced EGFR protein levels in the presence of TSA, which inactivates Arf1 and eventually inhibits invasion in HNSCC cells.

CONCLUSIONS

Our insights explore the critical role of EGFR-Arf1 complex in driving HNSCC progression, and demonstrate the selective action of HDAC inhibitors on this specific axis for suppressing HNSCC invasion. This novel finding represents the first example of modulating the EGFR-Arf1 complex in HNSCC by small molecule agents.

Glioma Cell Secretion: A Driver of Tumor Progression and a Potential Therapeutic Target

Cellular secretion is an important mediator of cancer progression. Secreted molecules in glioma are key components of complex autocrine and paracrine pathways that mediate multiple oncogenic pathologies. In this review, we describe tumor cell secretion in high-grade glioma and highlight potential novel therapeutic opportunities. Cancer Res; 78(21); 6031-9. ©2018 AACR.

Combating head and neck cancer metastases by targeting Src using multifunctional nanoparticle-based saracatinib

BACKGROUND

Inhibition of metastasis of head and neck squamous cell carcinoma (HNSCC) is one of the most important challenges in cancer treatment. Src, a non-receptor tyrosine kinase, has been implicated as a key promoter in tumor progression and metastasis of HNSCC. However, Src therapy for HNSCC is limited by lack of efficient in vivo delivery and underlying mechanisms remain elusive.

METHODS

Src knockdown cells were achieved by lentiviral-mediated interference. Cell migration and invasion were examined by wound healing and Transwell assays. Protein levels were determined by Western blot and/or immunohistochemistry. The Src inhibitor saracatinib was loaded into self-assembling nanoparticles by the solvent evaporation method. An experimental metastasis mouse model was generated to investigate the drug efficacy in metastasis.

RESULTS

Blockade of Src kinase activity by saracatinib effectively suppressed invasion and metastasis of HNSCC. Mechanistic assessment of the drug effects in HNSCC cells showed that saracatinib induced suppression of Src-dependent invasion/metastasis through downregulating the expression levels of Vimentin and Snail proteins. In tests in mice, saracatinib loaded into the novel multifunctional nanoparticles exhibited superior effects on suppression of HNSCC metastasis compared with the free drug, which is mainly attributed to highly specific and efficient tumor-targeted drug delivery system.

CONCLUSIONS

These findings and advances are of great importance to the development of Src-targeted nanomedicine as a more effective therapy for metastatic HNSCC.

Towards Resolving the Pro- and Anti-Tumor Effects of the Aryl Hydrocarbon Receptor

We have postulated that the aryl hydrocarbon receptor (AHR) drives the later, more lethal stages of some cancers when chronically activated by endogenous ligands. However, other studies have suggested that, under some circumstances, the AHR can oppose tumor aggression. Resolving this apparent contradiction is critical to the design of AHR-targeted cancer therapeutics. Molecular (siRNA, shRNA, AHR repressor, CRISPR-Cas9) and pharmacological (AHR inhibitors) approaches were used to confirm the hypothesis that AHR inhibition reduces human cancer cell invasion (irregular colony growth in 3D Matrigel cultures and Boyden chambers), migration (scratch wound assay) and metastasis (human cancer cell xenografts in zebrafish). Furthermore, these assays were used for a head-to-head comparison between AHR antagonists and agonists. AHR inhibition or knockdown/knockout consistently reduced human ER⁻/PR⁻/Her2⁻ and inflammatory breast cancer cell invasion, migration, and metastasis. This was associated with a decrease in invasion-associated genes (e.g., Fibronectin, VCAM1, Thrombospondin, MMP1) and an increase in CDH1/E-cadherin, previously associated with decreased tumor aggression. Paradoxically, AHR agonists (2,3,7,8-tetrachlorodibenzo-p-dioxin and/or 3,3′-diindolylmethane) similarly inhibited irregular colony formation in Matrigel and blocked metastasis in vivo but accelerated migration. These data demonstrate the complexity of modulating AHR activity in cancer while suggesting that AHR inhibitors, and, under some circumstances, AHR agonists, may be useful as cancer therapeutics.

Zbtb38 is a novel target for spinal cord injury

Spinal cord injury (SCI) is currently incurable since treatments applied to clinic are limited to minimizing secondary complications and the mechanisms of injury-induced spinal cord damage are poorly understood. Zbtb38, also called CIBZ, is highly expressed in spinal cord and it functions as a negative regulator in SCI-induced apoptosis. We show here that Zbtb38 is downregulated under endoplasmic reticulum (ER) stress, which promotes ER stress-associated apoptosis in human bone marrow neuroblastoma cells. In the traumatic SCI mice, ER stress presented in injured spinal cord induced repression of Zbtb38 expression and triggered Zbtb38-mediated apoptosis. ChIP-QPCR analysis revealed that ATF4, an ER-stress inducible transcription factor, directly activated Zbtb38 transcription by binding to the Zbtb38 promoter. However, this binding was significantly reduced following SCI, leading to a sharp decrease in Zbtb38 expression. Restoring Zbtb38 function in injured spinal cord by injection of lentivirus containing Zbtb38 into SCI mice, significantly alleviated secondary damage of spinal cord with decreased ER stress-associated apoptosis and partially recovered spinal cord functions. These findings demonstrate that restoration of Zbtb38 expression can reduce secondary tissue damage after SCI, and suggest that a therapeutic strategy for targeting Zbtb38 may promote functional recovery of spinal cord for patients with SCI.

Functional disruption of the Golgi apparatus protein ARF1 sensitizes MDA-MB-231 breast cancer cells to the antitumor drugs Actinomycin D and Vinblastine through ERK and AKT signaling

Increasing evidence indicates that the Golgi apparatus plays active roles in cancer, but a comprehensive understanding of its functions in the oncogenic transformation has not yet emerged. At the same time, the Golgi is becoming well recognized as a hub that integrates its functions of protein and lipid biosynthesis to signal transduction for cell proliferation and migration in cancer cells. Nevertheless, the active function of the Golgi apparatus in cancer cells has not been fully evaluated as a target for combined treatment. Here, we analyzed the effect of perturbing the Golgi apparatus on the sensitivity of the MDA-MB-231 breast cancer cell line to the drugs Actinomycin D and Vinblastine. We disrupted the function of ARF1, a protein necessary for the homeostasis of the Golgi apparatus. We found that the expression of the ARF1-Q71L mutant increased the sensitivity of MDA-MB-231 cells to both Actinomycin D and Vinblastine, resulting in decreased cell proliferation and cell migration, as well as in increased apoptosis. Likewise, the combined treatment of cells with Actinomycin D or Vinblastine and Brefeldin A or Golgicide A, two disrupting agents of the ARF1 function, resulted in similar effects on cell proliferation, cell migration and apoptosis. Interestingly, each combined treatment had distinct effects on ERK1/2 and AKT signaling, as indicated by the decreased levels of either phospho-ERK1/2 or phospho-AKT. Our results suggest that disruption of Golgi function could be used as a strategy for the sensitization of cancer cells to chemotherapy.

The Golgi complex in disease and therapy

The Golgi complex occupies a strategic position in the endomembrane system and acts not only as a key trafficking and sorting station and a vital biosynthetic center for glycoproteins and lipids, but also as an active signaling hub. As such, the Golgi complex participates in the establishment and maintenance of cell compartmentalization and in general, cell processes such as cell growth and apoptosis. The different functions of the Golgi complex are executed by composite molecular machineries that have been exhaustively dissected over the last three decades. These machineries can become dysfunctional as a result of mutations in the respective encoding genes or may be hijacked by infectious agents or misregulated in the course of multifactorial diseases such as neurodegeneration and cancer. Small molecules targeting components of these machineries have been instrumental in dissecting their functions in in vitro studies and some of them have been developed or are currently under development for clinical use.

Fishing for cures: The alLURE of using zebrafish to develop precision oncology therapies

Zebrafish have proven to be a valuable model to study human cancer biology with the ultimate aim of developing new therapies. Danio rerio are amenable to in vivo imaging, high-throughput drug screening, mutagenesis, and transgenesis, and they share histological and genetic similarities with Homo sapiens. The significance of zebrafish in the field of precision oncology is rapidly emerging. Indeed, modeling cancer in zebrafish has already been used to identify tumor biomarkers, define therapeutic targets and provide an in vivo platform for drug discovery. New zebrafish studies are starting to pave the way to direct individualized clinical applications. Patient-derived cancer cell xenograft models have demonstrated the feasibility of using zebrafish as a real-time avatar of prognosis and drug response to identify the most ideal therapy for an individual patient. Genetic cancer modeling in zebrafish, now facilitated by rapidly evolving genome editing techniques, represents another innovative approach to recapitulate human oncogenesis and develop individualized treatments. Utilizing zebrafish to design customizable precision therapies will improve the clinical outcome of patients afflicted with cancer.

The Arf-GAP and protein scaffold Cat1/Git1 as a multifaceted regulator of cancer progression

Cool-associated tyrosine phosphorylated protein 1 (Cat1), also referred to as GPCR-kinase interacting protein 1 (Git1), is a ubiquitously expressed, multi-domain protein that is best known for regulating cell shape and migration. Cat1/Git1 functions as a GTPase activating protein (GAP) that inactivates certain members of the ADP-ribosylation factor (Arf) family of small GTPases. It is also a scaffold that brings together several signaling proteins at specific locations within the cell, ensuring their efficient activation. Here we will discuss what is known regarding the classical role of Cat1/Git1 in the regulation of cell morphology and migration, as well as highlight some more recent findings that suggest this interesting signaling/scaffolding protein may also contribute in unexpected ways to oncogenic transformation.

Zebrafish Xenograft: An Evolutionary Experiment in Tumour Biology

Though the cancer research community has used mouse xenografts for decades more than zebrafish xenografts, zebrafish have much to offer: they are cheap, easy to work with, and the embryonic model is relatively easy to use in high-throughput assays. Zebrafish can be imaged live, allowing us to observe cellular and molecular processes in vivo in real time. Opponents dismiss the zebrafish model due to the evolutionary distance between zebrafish and humans, as compared to mice, but proponents argue for the zebrafish xenograft's superiority to cell culture systems and its advantages in imaging. This review places the zebrafish xenograft in the context of current views on cancer and gives an overview of how several aspects of this evolutionary disease can be addressed in the zebrafish model. Zebrafish are missing homologs of some human proteins and (of particular interest) several members of the matrix metalloproteinase (MMP) family of proteases, which are known for their importance in tumour biology. This review draws attention to the implicit evolutionary experiment taking place when the molecular ecology of the xenograft host is significantly different than that of the donor.

Combined targeting of Arf1 and Ras potentiates anticancer activity for prostate cancer therapeutics

Background

Although major improvements have been made in surgical management, chemotherapeutic, and radiotherapeutic of prostate cancer, many prostate cancers remain refractory to treatment with standard agents. Therefore, the identification of new molecular targets in cancer progression and development of novel therapeutic strategies to target them are very necessary for achieving better survival for patients with prostate cancer. Activation of small GTPases such as Ras and Arf1 is a critical component of the signaling pathways for most of the receptors shown to be upregulated in advanced prostate cancer.

Methods

The drug effects on cell proliferation were measured by CellTiter 96® AQueous One Solution Cell Proliferation Assay. The drug effects on cell migration and invasion were determined by Radius™ 24-well and Matrigel-coated Boyden chambers. The drug effects on apoptosis were assessed by FITC Annexin V Apoptosis Detection Kit with 7-AAD and Western blot with antibodies against cleaved PARP and Caspase 3. A NOD/SCID mouse model generated by subcutaneous injection was used to assess the in vivo drug efficacy in tumor growth. ERK activation and tumor cell proliferation in xenografts were examined by immunohistochemistry.

Results

We show that Exo2, a small-molecule inhibitor that reduces Arf1 activation, effectively suppresses prostate cancer cell proliferation by blocking ERK1/2 activation. Exo2 also has other effects, inhibiting migration and invasion of PCa cells and inducing apoptosis. The Ras inhibitor salirasib augments Exo2-induced cytotoxicity in prostate cancer cells partially by enhancing the suppression of ERK1/2 phosphorylation. In a xenograft mouse model of prostate cancer, Exo2 reduces prostate tumor burden and inhibits ERK1/2 activation at a dose of 20 mg/kg. Synergistic treatment of salirasib and Exo2 exhibits a superior inhibitory effect on prostate tumor growth compared with either drug alone, which may be attributed to the more efficient inhibition of ERK1/2 phosphorylation.

Conclusion

This study suggests that simultaneous blockade of Arf1 and Ras activation in prostate cancer cells is a potential targeted therapeutic strategy for preventing prostate cancer development.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-017-0583-4) contains supplementary material, which is available to authorized users.

Augmentation of the anticancer activity of CYT997 in human prostate cancer by inhibiting Src activity

Background

Abnormalities of tubulin polymerization and microtubule assembly are often seen in cancer, which make them very suitable targets for the development of therapeutic approach against rapidly dividing and aggressive cancer cells. CYT997 is a novel microtubule-disrupting agent with anticancer activity in multiple cancer types including prostate cancer. However, the molecular mechanisms of action of CYT997 in prostate cancer have not been well characterized.

Methods

Src knockdown cells were achieved by lentiviral-mediated interference. The drug effects on cell proliferation were measured by MTS. The drug effects on cell viability and death were determined by Cell Titer-Glo® Luminescent cell viability kit and flow cytometry with Zombie Aqua™ staining. The drug effects on apoptosis were assessed by Cell Death Detection Elisa kit and Western blot with a cleaved PARP antibody. The drug effects on cell invasion were examined by Matrigel-coated Boyden chambers. Oxidative stress was detected by DCFH-DA staining and electrochemical biosensor. Mouse models generated by subcutaneous or intracardiac injection were used to investigate the in vivo drug efficacy in tumor growth and metastasis.

Results

CYT997 effectively inhibited proliferation, survival, and invasion of prostate cancer cells via blocking multiple oncogenic signaling cascades but not the Src pathway. Inhibition of Src expression by small hairpin RNA or inactivation of Src by dasatinib increased the CYT997-induced cytotoxicity of in vitro. Moreover, the combination of dasatinib and CYT997 exhibited a superior inhibitory effect on tumor growth and metastasis compared with either of the drugs alone.

Conclusion

Our findings demonstrate that blockage of Src augments the anticancer effect of CYT997 on prostate cancer and suggest that co-treatment of dasatinib and CYT997 may represent an effective therapeutic regimen for limiting prostate cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-017-0485-0) contains supplementary material, which is available to authorized users.

KLHL21, a novel gene that contributes to the progression of hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) has very high prevalence and associated-mortality. However, targeted therapies that are currently used in clinical practice for HCC have certain limitations, in part because of the lack of reliable and clinically applicable biomarkers that can be used for diagnosis and prognosis assessments and for the surveillance of treatment effectiveness.

METHODS

Meta-analysis was used to analyze the integrated microarray data for global identification of a set of robust biomarkers for HCC. Quantitative RT-PCR (qRT-PCR) was performed to validate the expression levels of selected genes. Gene expression was inhibited by siRNA. CellTiter 96® AQueous One Solution Cell Proliferation assays were used to determine cell proliferation, and Transwell assays were used to determine cell migration and invasion potential.

RESULTS

Meta-analysis of the expression data provided a gene expression signature from a total of 1525 patients with HCC, showing 1529 up-regulated genes and 478 down-regulated genes in cancer samples. The expression levels of genes having strong clinical significance were validated by qRT-PCR using primary HCC tissues and the paired adjacent noncancerous liver tissues. Up-regulation of VPS45, WIPI1, TTC1, IGBP1 and KLHL21 genes and down-regulation of FCGRT gene were confirmed in clinical HCC samples. KLHL21 was the most promising gene for potential use as a bioclinical marker in this analysis. Abrogating expression of it significantly inhibited cell proliferation, migration and invasion.

CONCLUSIONS

Our study suggests that KLHL21 is a potential target for therapeutic intervention. Our findings also provide novel candidate genes on a genome-wide scale, which may have significant impact on the design and execution of effective therapy of HCC patients.