Down-regulation of ARNT promotes cancer metastasis by activating the fibronectin/integrin β1/FAK axis

The promotion of cell proliferation and invasion in cutaneous squamous cell carcinomas after ARNT downregulation is associated with CXCL3

The aryl hydrocarbon receptor nuclear translocator (ARNT) is a transcription factor associated with adaptive responses to cellular stress. Its role in cutaneous squamous cell carcinoma (cSCC) remains poorly understood. The aim of this study was to investigate the role of ARNT in cSCC. Immunohistochemistry revealed downregulation of ARNT in cSCC, precancerous lesions (actinic keratosis), and cells. Knockdown of ARNT in A431 and SCL-1 cells significantly enhanced cell growth and metastasis. Microarray analysis and Ingenuity Pathway Analysis confirmed that loss of ARNT in A431 cells was highly correlated with cell growth and movement and upregulated CXCL3 expression. Cellular and xenograft experiments further confirmed that ARNT regulates cSCC proliferation and invasiveness in a CXCL3-dependent manner. ARNT may regulate CXCL3 expression through ROS-STAT3 pathway. In conclusion, this study demonstrates that ARNT plays a critical role in the development of cSCC and significantly affects the proliferation and metastatic ability of cSCC cells. It has the potential to serve as an ideal treatment target for cSCC.

Non-Susceptibility Gene Variants in Head and Neck Paragangliomas

Head and neck paragangliomas (HNPGLs) are rare neoplasms that, along with pheochromocytomas and extra-adrenal paragangliomas, are associated with inherited mutations in at least 12 susceptibility genes in approximately 40% of cases. However, due to the rarity of HNPGLs, only a series of small-scale studies and individual cases have reported mutations in additional genes that may be involved in tumorigenesis. Consequently, numerous disease-causing mutations and genes responsible for the pathogenesis of HNPGLs remain poorly investigated. The aim of this study was to gain a deeper understanding of the genetic basis of HNPGLs by focusing on variants in genes that were not previously identified as well-known drivers. A whole-exome data analysis was conducted on a representative set of 152 HNPGLs. In 30% of the tumors examined, 53 potentially deleterious variants were identified in 36 different genes. The analysis identified pathogenic or likely pathogenic variants in the ARNT, IDH2, L2HGDH, MYH3, PIK3CA, and TERT genes. A functional network analysis of the mutated genes revealed numerous associations and a list of metabolic pathways (e.g., the TCA cycle, carbon metabolism, pyruvate metabolism, etc.) and signaling pathways (e.g., HIF1, PI3K-Akt, FoxO, AMPK, MAPK, etc.) that may play an important role in the development of HNPGLs. The identified range of genetic alterations affecting multiple genes and, potentially, influencing diverse cellular pathways provides an enhanced molecular genetic characterization of HNPGLs.

Molecular mechanism of anticancer effect of heat shock protein 90 inhibitor BIIB021 in human bladder cancer cell line

Bladder cancer is a type of urologic malignancy that exhibits significant morbidity, mortality, and treatment costs. Inhibition of heat shock protein 90 (HSP90) activity has been a promising pharmacological strategy for blocking of bladder cancer pathogenesis. BIIB021 is a next-generation HSP90 inhibitor which interrupts ATP hydrolysis process of HSP90 and inhibits the stabilization and correct folding of client proteins. In current study, we aimed to investigate the molecular mechanism of the anticancer activity of BIIB021 in human bladder cancer T24 cells. Our results revealed that nanomolar concentration of BIIB021 decreased viability of T24 cell. BIIB021 downregulated HSP90 expression in T24 cells and inhibited the refolding activity of luciferase in the presence of T24 cell lysate. PCR array data indicated a significant alteration in transcript levels of cancer-related genes involved in metastases, apoptotic cell death, cell cycle, cellular senescence, DNA damage and repair mechanisms, epithelial-to-mesenchymal transition, hypoxia, telomeres and telomerase, and cancer metabolism pathways in T24 cells. All findings hypothesize that BIIB021 could exhibit as effective HSP90 inhibitor in the future for treatment of bladder cancer patients.

Targeting Hypoxia-Inducible Factor-1 (HIF-1) in Cancer: Emerging Therapeutic Strategies and Pathway Regulation

Hypoxia-inducible factor-1 (HIF-1) is a key regulator for balancing oxygen in the cells. It is a transcription factor that regulates the expression of target genes involved in oxygen homeostasis in response to hypoxia. Recently, research has demonstrated the multiple roles of HIF-1 in the pathophysiology of various diseases, including cancer. It is a crucial mediator of the hypoxic response and regulator of oxygen metabolism, thus contributing to tumor development and progression. Studies showed that the expression of the HIF-1α subunit is significantly upregulated in cancer cells and promotes tumor survival by multiple mechanisms. In addition, HIF-1 has potential contributing roles in cancer progression, including cell division, survival, proliferation, angiogenesis, and metastasis. Moreover, HIF-1 has a role in regulating cellular metabolic pathways, particularly the anaerobic metabolism of glucose. Given its significant and potential roles in cancer development and progression, it has been an intriguing therapeutic target for cancer research. Several compounds targeting HIF-1-associated processes are now being used to treat different types of cancer. This review outlines emerging therapeutic strategies that target HIF-1 as well as the relevance and regulation of the HIF-1 pathways in cancer. Moreover, it addresses the employment of nanotechnology in developing these promising strategies.

The Anticancer Effects of the Garlic Organosulfide Diallyl Trisulfide through the Attenuation of B[a]P-Induced Oxidative Stress, AhR Expression, and DNA Damage in Human Premalignant Breast Epithelial (MCF-10AT1) Cells

Benzo[a]pyrene (B[a]P) is the most characterized polycyclic aromatic hydrocarbon associated with breast cancer. Our lab previously reported that the organosulfur compound (OSC), diallyl trisulfide (DATS), chemoprevention mechanism works through the induction of cell cycle arrest and a reduction in oxidative stress and DNA damage in normal breast epithelial cells. We hypothesize that DATS will inhibit B[a]P-induced cancer initiation in premalignant breast epithelial (MCF-10AT1) cells. In this study, we evaluated the ability of DATS to attenuate B[a]P-induced neoplastic transformation in MCF-10AT1 cells by measuring biological endpoints such as proliferation, clonogenicity, reactive oxygen species (ROS) formation, and 8-hydroxy-2-deoxyguanosine (8-OHdG) DNA damage levels, as well as DNA repair and antioxidant proteins. The results indicate that B[a]P induced proliferation, clonogenic formation, ROS formation, and 8-OHdG levels, as well as increasing AhR, ARNT/HIF-1β, and CYP1A1 protein expression compared with the control in MCF-10AT1 cells. B[a]P/DATS's co-treatment (CoTx) inhibited cell proliferation, clonogenic formation, ROS formation, AhR protein expression, and 8-OHdG levels compared with B[a]P alone and attenuated all the above-mentioned B[a]P-induced changes in protein expression, causing a chemopreventive effect. This study demonstrates, for the first time, that DATS prevents premalignant breast cells from undergoing B[a]P-induced neoplastic transformation, thus providing more evidence for its chemopreventive effects in breast cancer.

Cell cycle protein BORA is associated with colorectal cancer progression by AURORA-PLK1 cascades: a bioinformatics analysis

Colorectal cancer (CRC) is the third most diagnosed cancer in the world. A better understanding of the molecular mechanism of CRC is essential for making novel strategies for the CRC management and its prevention. The present study aims to explore the molecular mechanism through integrated bioinformatics analysis by analyzing genes and their co-expression pattern in normal and CRC states. GSE110223, GSE110224 and GSE113513 gene expression profiles were analyzed in this study. The co-expression networks for normal and tumor samples were constructed separately and analyzed to identify the modules, sub-networks and key genes. Gene regulatory network analysis was done to understand the regulatory mechanism of selected genes. Survival analysis was performed for the identified sub-networks and key genes to understand their role in CRC progression. A total of seven modules were detected and the KEGG pathway analysis revealed these modules were mainly enriched with cell cycle, metabolism and signaling-related pathways. E2F6 and ETV4 transcription factors regulating the activity of multiple genes of identified modules were found to be up-regulated in CRC. Six Sub-networks and seven key genes, BORA, CCT7, DTL, RUVBL1, RUVBL2, THEM6 and TMEM97 associated with the CRC progression were identified. Disease-gene association analysis identified a novel association of the BORA gene with CRC that activates and regulates the AURORA-PLK1 cascades in the cell cycle. Survival analysis indicates that the overexpressed BORA is associated with unfavourable overall survival in CRC. The mechanistic role of BORA in the regulation of cell cycle progression suggests that BORA might act as a potential therapeutic target for CRC.

PCB: A pseudotemporal causality-based Bayesian approach to identify EMT-associated regulatory relationships of AS events and RBPs during breast cancer progression

During breast cancer metastasis, the developmental process epithelial-mesenchymal (EM) transition is abnormally activated. Transcriptional regulatory networks controlling EM transition are well-studied; however, alternative RNA splicing also plays a critical regulatory role during this process. Alternative splicing was proved to control the EM transition process, and RNA-binding proteins were determined to regulate alternative splicing. A comprehensive understanding of alternative splicing and the RNA-binding proteins that regulate it during EM transition and their dynamic impact on breast cancer remains largely unknown. To accurately study the dynamic regulatory relationships, time-series data of the EM transition process are essential. However, only cross-sectional data of epithelial and mesenchymal specimens are available. Therefore, we developed a pseudotemporal causality-based Bayesian (PCB) approach to infer the dynamic regulatory relationships between alternative splicing events and RNA-binding proteins. Our study sheds light on facilitating the regulatory network-based approach to identify key RNA-binding proteins or target alternative splicing events for the diagnosis or treatment of cancers. The data and code for PCB are available at: http://hkumath.hku.hk/~wkc/PCB(data+code).zip.

Hypoxia and HIFs in Ewing sarcoma: new perspectives on a multi-facetted relationship

Hypoxia develops during the growth of solid tumors and influences tumoral activity in multiple ways. Low oxygen tension is also present in the bone microenvironment where Ewing sarcoma (EwS) - a highly aggressive pediatric cancer - mainly arises. Hypoxia inducible factor 1 subunit alpha (HIF-1-a) is the principal molecular mediator of the hypoxic response in cancer whereas EWSR1::FLI1 constitutes the oncogenic driver of EwS. Interaction of the two proteins has been shown in EwS. Although a growing body of studies investigated hypoxia and HIFs in EwS, their precise role for EwS pathophysiology is not clarified to date. This review summarizes and structures recent findings demonstrating that hypoxia and HIFs play a role in EwS at multiple levels. We propose to view hypoxia and HIFs as independent protagonists in the story of EwS and give a perspective on their potential clinical relevance as prognostic markers and therapeutic targets in EwS treatment.

Polymorphism, Expression, and Structure Analysis of a Key Gene ARNT in Sheep (Ovis aries)

Growth traits are influential factors that significantly affects the development of the sheep industry. A previous TMT proteomic analysis found that a key protein in the HIF signaling pathway, ARNT, may influence embryonic skeletal muscle growth and development in sheep. The purpose of this study was to better understand the association between the polymorphisms of ARNT and growth traits of sheep, and the potential function of ARNT. Real-time qPCR (qRT-PCR) of ARNT was carried out to compare its expression in different developmental stages of the muscle tissues and primary myoblasts in the Hu, Chinese merino, and Gangba sheep. The genetic variance of ARNT was detected using the Illumina Ovine SNP 50 K and 600 K BeadChip in the Hu and Ujimqin sheep populations, respectively. The CDS sequence of the ARNT gene was cloned in the Hu sheep using PCR technology. Finally, bioinformatic analytical methods were applied to characterize the genes and their hypothetical protein products. The qRT-PCR results showed that the ARNT gene was expressed significantly in the Chinese merino embryo after 85 gestation days (D85) (p < 0.05). Additionally, after the sheep were born, the expression of ARNT was significant at the weaning stage of the Hu sheep (p < 0.01). However, there was no difference in the Gangba sheep.In addition, six SNP loci were screened using 50 K and 600 K BeadChip. We found a significant association between rs413597480 A > G and the Hu sheep weight at weaning and backfat thickness in the 5-month-old sheep (p < 0.05), and four SNP loci (rs162298018 G > C, rs159644025 G > A, rs421351865 G > A, and rs401758103 A > G) were also associated with growth traits in the Ujimqin sheep (p < 0.05). Interestingly, we found that a G > C mutation at 1948 bp in the cloned ARNT CDS sequence of the Hu sheep was the same locus mutation as rs162298018 G > C identified using the 600 K BeadChip, which resulted in a nonconservative missense point mutation, leading to a change from proline to alanine and altering the number of DNA, protein-binding sites, and the α-helix of the ARNT protein. There was a strong linkage disequilibrium between rs162298018 G > C and rs159644025 G > A, and the ARNT protein was conserved among the goat, Hu sheep, and Texel sheep. And, we propose that a putative molecular marker for growth and development in sheep may be the G > C mutation at 1948 bp in the CDS region of the ARNT gene. Our study systematically analyzed the expression, structure, and function of the ARNT gene and its encoded proteins in sheep. This provides a basis for future studies of the regulatory mechanisms of the ARNT gene.

Alternative Splicing of the Aryl Hydrocarbon Receptor Nuclear Translocator (ARNT) Is Regulated by RBFOX2 in Lymphoid Malignancies

Aberrant alternative splicing (AS) of pre-mRNAs promotes the development and proliferation of cancerous cells. Accordingly, we had previously observed higher levels of the aryl hydrocarbon receptor nuclear translocator (ARNT) spliced variant isoform 1 in human lymphoid malignancies compared to that in normal lymphoid cells, which is a consequence of increased inclusion of alternative exon 5. ARNT is a transcription factor that has been implicated in the survival of various cancers. Notably, we found that ARNT isoform 1 promoted the growth and survival of lymphoid malignancies, but the regulatory mechanism controlling ARNT AS is unclear. Here, we report cis- and trans-regulatory elements which are important for the inclusion of ARNT exon 5. Specifically, we identified recognition motifs for the RNA-binding protein RBFOX2, which are required for RBFOX2-mediated exon 5 inclusion. RBFOX2 upregulation was observed in lymphoid malignancies, correlating with the observed increase in ARNT exon 5 inclusion. Moreover, suppression of RBFOX2 significantly reduced ARNT isoform 1 levels and cell growth. These observations reveal RBFOX2 as a critical regulator of ARNT AS in lymphoid malignancies and suggest that blocking the ARNT-specific RBFOX2 motifs to decrease ARNT isoform 1 levels is a viable option for targeting the growth of lymphoid malignancies.

Identification of phenotype-specific networks from paired gene expression-cell shape imaging data

The morphology of breast cancer cells is often used as an indicator of tumor severity and prognosis. Additionally, morphology can be used to identify more fine-grained, molecular developments within a cancer cell, such as transcriptomic changes and signaling pathway activity. Delineating the interface between morphology and signaling is important to understand the mechanical cues that a cell processes in order to undergo epithelial-to-mesenchymal transition and consequently metastasize. However, the exact regulatory systems that define these changes remain poorly characterized. In this study, we used a network-systems approach to integrate imaging data and RNA-seq expression data. Our workflow allowed the discovery of unbiased and context-specific gene expression signatures and cell signaling subnetworks relevant to the regulation of cell shape, rather than focusing on the identification of previously known, but not always representative, pathways. By constructing a cell-shape signaling network from shape-correlated gene expression modules and their upstream regulators, we found central roles for developmental pathways such as WNT and Notch, as well as evidence for the fine control of NF-kB signaling by numerous kinase and transcriptional regulators. Further analysis of our network implicates a gene expression module enriched in the RAP1 signaling pathway as a mediator between the sensing of mechanical stimuli and regulation of NF-kB activity, with specific relevance to cell shape in breast cancer.

Human placental villous stromal extracellular matrix regulates fetoplacental angiogenesis in severe fetal growth restriction

Pregnancies complicated by severe, early-onset fetal growth restriction with abnormal Doppler velocimetry (FGRadv) have a sparse villous vascular tree secondary to impaired angiogenesis. As endothelial cell (EC) and stromal matrix interactions are key regulators of angiogenesis, we investigated the role of placental stromal villous matrix on fetoplacental EC angiogenesis. We have developed a novel model of generating placental fibroblast (FB) cell-derived matrices (CDMs), allowing us to interrogate placenta-specific human EC and stromal matrix interactions and their effects on fetoplacental angiogenesis. We found that as compared with control ECs plated on control matrix, FGRadv ECs plated on FGRadv matrix exhibited severe migrational defects, as measured by velocity, directionality, accumulated distance, and Euclidean distance in conjunction with less proliferation. However, control ECs, when interacting with FGRadv CDM, also demonstrated significant impairment in proliferation and migratory properties. Conversely several angiogenic attributes were rescued in FGRadv ECs subjected to control matrix, demonstrating the importance of placental villous stromal matrix and EC-stromal matrix interactions in regulation of fetoplacental angiogenesis.

Discovery of Antimetastatic Chiral Ionone Alkaloid Derivatives Targeting HIF-1α/VEGF/VEGFR2 Pathway

Novel chiral ionone alkaloid derivatives were synthesized and their antimetastatic effects were evaluated in human breast cancer cells using chemotaxis assay. Compared with positive control LY294002, a PI3 K inhibitor, derivatives 10 a, 11 a, 11 c, 11 g, 11 j, 11 k and 11 w exhibited significant inhibitory effects against cancer cell migration. Especially, the IC₅₀ for compound 11 g was as low as 0.035±0.004 μM. Further investigations on compound 11 g revealed that it could exert inhibitory effects on the adhesion, migration and invasion of MDA-MB-231 cells. The mechanisms for the antitumor metastatic effects of 11 g might be through the inhibition of HIF-1α/VEGF/VEGFR2/Akt pathway, which suppressed the downstream signaling molecules, including Akt1/mTOR/p70S6K and Akt2/PKCζ/integrin β1 pathways. Taken together, chiral ionone alkaloid derivative 11 g has the potential to be developed into an antitumor metastatic agent for breast cancer.

ARNT deficiency represses pyruvate dehydrogenase kinase 1 to trigger ROS production and melanoma metastasis

The metabolic changes in melanoma cells that are required for tumor metastasis have not been fully elucidated. In this study, we show that the increase in glucose uptake and mitochondrial oxidative phosphorylation confers metastatic ability as a result of aryl hydrocarbon receptor nuclear translocator (ARNT) deficiency. In clinical tissue specimens, increased ARNT, pyruvate dehydrogenase kinase 1 (PDK1), and NAD(P)H quinine oxidoreductase-1 (NQO1) was observed in benign nevi, whereas lower expression was observed in melanoma. The depletion of ARNT dramatically repressed PDK1 and NQO1 expression, which resulted in an increase of ROS levels. The elimination of ROS using N-acetylcysteine (NAC) and inhibition of oxidative phosphorylation using carbonyl cyanide m-chlorophenyl hydrazone (CCCP) and rotenone inhibited the ARNT and PDK1 deficiency-induced cell migration and invasion. In addition, ARNT deficiency in tumor cells manipulated the glycolytic pathway through enhancement of the glucose uptake rate, which reduced glucose dependence. Intriguingly, CCCP and NAC dramatically inhibited ARNT and PDK1 deficiency-induced tumor cell extravasation in mouse models. Our work demonstrates that downregulation of ARNT and PDK1 expression serves as a prognosticator, which confers metastatic potential as the metastasizing cells depend on metabolic changes.

Functional annotation of melanoma risk loci identifies novel susceptibility genes

Genome-wide association study (GWAS)-identified single-nucleotide polymorphisms (SNPs) are tag SNPs located in both transcribed and non-coding regulatory DNA regions, rather than representing causal or functional variants for disease. To identify functional variants or genes for melanoma susceptibility, we used functional mapping and annotation (FUMA) to perform functional annotation of the summary statistics of 2541 significant melanoma risk SNPs (P < 5 × 10-8) identified by GWAS. The original GWAS melanoma study included 15 990 cases and 26 409 controls, representing the largest international meta-analysis of melanoma susceptibility. We prioritized 330 unique genes, including those in immune cytokine signaling pathways, from 19 loci through positional, expression quantitative trait locus, and chromatin interaction mapping. In comparison, only 38 melanoma-related genes were identified in the original meta-analysis. In addition to the well-known melanoma susceptibility genes confirmed in the meta-analysis (MC1R, CDKN2A, TERT, OCA2 and ARNT/SETDB1), we also identified additional novel genes using FUMA to map SNPs to genes. Through chromatin interaction mapping, we prioritized IFNA7, IFNA10, IFNA16, IFNA17, IFNA14, IFNA6, IFNA21, IFNA4, IFNE and IFNA5; these 10 most significant genes are all involved in immune system and cytokine signaling pathways. In the gene analysis, we identified 72 genes with a P < 2.5 × 10-6. The genes associated with melanoma risk were DEF8 (P = 1.09 × 10-57), DBNDD1 (P = 2.19 × 10-42), SPATA33 (P = 3.54 × 10-38) and MC1R (P = 1.04 × 10-36). In summary, this study identifies novel putative melanoma susceptibility genes and provides a guide for further experimental validation of functional variants and disease-related genes.

Fibronectin and colorectal cancer: signaling pathways and clinical implications

Colorectal cancer (CRC) is the fourth leading cause of cancer deaths worldwide, with poor prognosis mainly related to metastasis. Fibronectin (FN), a vital component of the extracellular matrix (ECM), has been found involved in tumorigenesis and malignant progression in different types of malignancy. Numerous studies have indicated the distinct expression of FN in various cancers and demonstrated the different functions of FN in the proliferation, migration, and invasion of cancers. Meanwhile, FN isoforms have been extensively used for targeted drug delivery and imaging for tumors. Although a growing number of studies on FN in CRC have been reported, integrated reviews on the relationship between FN and CRC are rare. In this review, we will summarize the association between FN and CRC, including the signaling pathways and molecules involved in, as well as potential diagnostic and therapeutic values of FN for patients with CRC.

Does NLRP3 Inflammasome and Aryl Hydrocarbon Receptor Play an Interlinked Role in Bowel Inflammation and Colitis-Associated Colorectal Cancer?

Inflammation is a hallmark in many forms of cancer; with colitis-associated colorectal cancer (CAC) being a progressive intestinal inflammation due to inflammatory bowel disease (IBD). While this is an exemplification of the negatives of inflammation, it is just as crucial to have some degree of the inflammatory process to maintain a healthy immune system. A pivotal component in the maintenance of such intestinal homeostasis is the innate immunity component, inflammasomes. Inflammasomes are large, cytosolic protein complexes formed following stimulation of microbial and stress signals that lead to the expression of pro-inflammatory cytokines. The NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome has been extensively studied in part due to its strong association with colitis and CAC. The aryl hydrocarbon receptor (AhR) has recently been acknowledged for its connection to the immune system aside from its role as an environmental sensor. AhR has been described to play a role in the inhibition of the NLRP3 inflammasome activation pathway. This review will summarise the signalling pathways of both the NLRP3 inflammasome and AhR; as well as new-found links between these two signalling pathways in intestinal immunity and some potential therapeutic agents that have been found to take advantage of this link in the treatment of colitis and CAC.

Vascular Endothelial Growth Inhibitor, a Cytokine of the Tumor Necrosis Factor Family, is Associated With Epithelial-Mesenchymal Transition in Renal Cell Carcinoma

Previous studies have revealed that the activation of the epithelial-mesenchymal transition (EMT) endows metastatic properties upon cancer cells to promote invasion and migration. In this study, immunohistochemical analysis was performed in 50 cases of clear cell renal cell carcinoma (RCC) and paired normal kidney tissues. We detected the expression of vascular endothelial growth inhibitor (VEGI) and EMT markers (E-cadherin, fibronectin, and Slug) and recorded the clinical, pathologic, and follow-up (median follow-up: 79.0 mo) information. The expression of VEGI and E-cadherin was significantly lower in RCC tissues compared with normal kidney tissues (P<0.001). However, the expression of fibronectin and Slug was higher in RCC tissues (P<0.05). VEGI and EMT marker expression marginally differed in tumor size and stage. Significant differences were found in the pathologic grade (P<0.05). The Spearman correlation analysis suggested a positive correlation between VEGI and E-cadherin (r=0.451, P<0.01). A negative correlation was shown between VEGI and fibronectin (r=-0.465, P<0.01). There was also a negative correlation between VEGI and Slug (r=-0.758, P<0.01). During the 79.0 months (range, 7 to 119 mo) of follow-up, 6 patients died due to RCC, and the tumor-free survival rate was 88% (44/50). We did not find a significant correlation between VEGI/EMT markers (E-cadherin, fibronectin, and Slug) and overall survival (P>0.05). Our findings indicate that VEGI plays an important role in EMT in RCC. It suggests that VEGI may be investigated as a disease biomarker and therapeutic target in RCC.

Semaphorin 6A Attenuates the Migration Capability of Lung Cancer Cells via the NRF2/HMOX1 Axis

Cell migration is a fundamental feature of cancer recurrence. Since recurrence is correlated with high mortality in lung cancer, it follows that reducing cell migration would decrease recurrence and increase survival rates. Semaphorin-6A (SEMA6A), a protein initially known as a regulator of axonal guidance, is down-regulated in lung cancer tissue, and low levels of SEMA6A are associated with cancer recurrence. Thus, we hypothesized that SEMA6A could suppress cancer cell migration. In this study, we found that the migration capability of H1299 lung cancer cells decreased with SEMA6A overexpression, while it increased with SEMA6A silencing. Moreover, silencing of the cellular homeostasis protein Heme-oxygenase-1 (HMOX1) and/or the transcription factor Nuclear Factor, Erythroid-2-Like-2 (NRF2) reversed the migration-suppressing effect of SEMA6A and the SEMA6A-driven alterations in expression of urokinase insulin-like-growth-factor-binding-protein-3, Matrix metalloproteinase (MMP)-1, and MMP9, the downstream effectors of HMOX1. Taken together, these results demonstrate that SEMA6A is a potential suppressor of cancer migration that functions through the NRF2/HMOX1 axis. Our results explain why low SEMA6A is linked to high recurrence in the clinical setting and suggest that SEMA6A could be useful as a biomarker or target in lung cancer therapy.

Targeting integrins for cancer management using nanotherapeutic approaches: Recent advances and challenges

Integrins are the main cell surface receptors and execute multifaceted functions such as the bidirectional transmission of signals (i.e., inside-out and outside-in) and provide communication between cells and their microenvironments. Integrins are the key regulators of critical biological functions and contribute significantly to the promotion of cancer at almost every stage of disease progression from initial tumor formation to metastasis. Integrin expressions are frequently altered in different cancers, and consequently, several therapeutic strategies targeting integrins have been developed. Furthermore, nanotechnology-based approaches have been devised to overcome the intrinsic limitations of conventional therapies for cancer management, and have been shown to more precise, safer, and highly effective therapeutic tools. Although nanotechnology-based approaches have achieved substantial success for the management of cancer, certain obstacles remain such as inadequate knowledge of nano-bio interactions and the challenges associated with the three stages of clinical trials. This review highlights the different roles of integrins and of integrin-dependent signaling in various cancers and describes the applications of nanotherapeutics targeting integrins. In addition, we discuss RGD-based approaches and challenges posed to cancer management.

Fibronectin Promotes Cell Growth and Migration in Human Renal Cell Carcinoma Cells

The prognostic and therapeutic values of fibronectin have been reported in patients with renal cell carcinoma (RCC). However, the underlying mechanisms of malignancy in RCC are not completely understood. We found that silencing of fibronectin expression attenuated human RCC 786-O and Caki-1 cell growth and migration. Silencing of potential fibronectin receptor integrin α5 and integrin β1 decreased 786-O cell ability in movement and chemotactic migration. Biochemical examination revealed a reduction of cyclin D1 and vimentin expression, transforming growth factor-β1 (TGF-β1) production, as well as Src and Smad phosphorylation in fibronectin-silenced 786-O and Caki-1 cells. Pharmacological inhibition of Src decreased 786-O cell growth and migration accompanied by a reduction of cyclin D1, fibronectin, vimentin, and TGF-β1 expression, as well as Src and Smad phosphorylation. In 786-O cells, higher activities in cell growth and migration than in Caki-1 cells were noted, along with elevated fibronectin and TGF-β1 expression. The additions of exogenous fibronectin and TGF-β1 promoted Caki-1 cell growth and migration, and increased cyclin D1, fibronectin, vimentin, and TGF-β1 expression, as well as Src and Smad phosphorylation. These findings highlight the role of fibronectin in RCC cell growth and migration involving Src and TGF-β1 signaling.

Novel potential causative genes in carotid paragangliomas

Background

Carotid paragangliomas (CPGLs) are rare neuroendocrine tumors that arise from the paraganglion at the bifurcation of the carotid artery and are responsible for approximately 65% of all head and neck paragangliomas. CPGLs can occur sporadically or along with different hereditary tumor syndromes. Approximately 30 genes are known to be associated with CPGLs. However, the genetic basis behind the development of these tumors is not fully elucidated, and the molecular mechanisms underlying CPGL pathogenesis remain unclear.

Methods

Whole exome and transcriptome high-throughput sequencing of CPGLs was performed on an Illumina platform. Exome libraries were prepared using a Nextera Rapid Capture Exome Kit (Illumina) and were sequenced under 75 bp paired-end model. For cDNA library preparation, a TruSeq Stranded Total RNA Library Prep Kit with Ribo-Zero Gold (Illumina) was used; transcriptome sequencing was carried out with 100 bp paired-end read length. Obtained data were analyzed using xseq which estimates the influence of mutations on gene expression profiles allowing to identify potential causative genes.

Results

We identified a total of 16 candidate genes (MYH15, CSP1, MYH3, PTGES3L, CSGALNACT2, NMD3, IFI44, GMCL1, LSP1, PPFIBP2, RBL2, MAGED1, CNIH3, STRA6, SLC6A13, and ATM) whose variants potentially influence their expression (cis-effect). The strongest cis-effect of loss-of-function variants was found in MYH15, CSP1, and MYH3, and several likely pathogenic variants in these genes associated with CPGLs were predicted.

Conclusions

Using the xseq probabilistic model, three novel potential causative genes, namely MYH15, CSP1, and MYH3, were identified in carotid paragangliomas.

Heterotypic CAF-tumor spheroids promote early peritoneal metastatis of ovarian cancer

The study provides insights in HGSOC by identifying that ascitic CAFs selectively recruit ITGA5^high ascitic tumor cells to form heterotypic spheroids named metastatic units (MUs), which actively engage in peritoneal metastasis, discriminates HGSOC from LGSOC, and act as therapeutic targets in hampering OC metastasis.

High-grade serous ovarian cancer (HGSOC) is hallmarked by early onset of peritoneal dissemination, which distinguishes it from low-grade serous ovarian cancer (LGSOC). Here, we describe the aggressive nature of HGSOC ascitic tumor cells (ATCs) characterized by integrin α5^high (ITGA5^high) ATCs, which are prone to forming heterotypic spheroids with fibroblasts. We term these aggregates as metastatic units (MUs) in HGSOC for their advantageous metastatic capacity and active involvement in early peritoneal dissemination. Intriguingly, fibroblasts inside MUs support ATC survival and guide their peritoneal invasion before becoming essential components of the tumor stroma in newly formed metastases. Cancer-associated fibroblasts (CAFs) recruit ITGA5^high ATCs to form MUs, which further sustain ATC ITGA5 expression by EGF secretion. Notably, LGSOC is largely devoid of CAFs and the resultant MUs, which might explain its metastatic delay. These findings identify a specialized MU architecture that amplifies the tumor–stroma interaction and promotes transcoelomic metastasis in HGSOC, providing the basis for stromal fibroblast-oriented interventions in hampering OC peritoneal propagation.

Fibronectin promotes nasopharyngeal cancer cell motility and proliferation

Nasopharyngeal cancer (NPC) is an Epstein-Barr virus (EBV)-associated carcinoma. Fibronectin is regarded as a prognosticator in NPC and its involvement in cell motility has been reported in EBV infection and viral latent membrane protein 1 (LMP1) overexpression NPC cell lines. However, its malignant potential in NPC cell lines without harbouring the EBV genome has not been investigated. We investigatd and compared among four NPC cell lines, and the results revealed a positive association between fibronectin levels and NPC cell motility as well as proliferation. Studies of antibody neutralization, exogenous addition, overexpression, and RNA interference confirmed a migration role of fibronectin in NPC cells involving integrin α5, Src, Rac1, and Cdc42, implying a mesenchymal-like cell movement. Furthermore, hypoxia-inducible factor-1α (HIF-1α) and transforming growth factor-β1 (TGF-β1) were identified as alternative activators of fibronectin expression and NPC cell migration. Besides cell migration, studies of RNA interference also showed a stimulatory effect of fibronectin in NPC cell proliferation. Mechanistic studies further revealed a subsequent reduction of HIF-1α, TGF-β1, cyclin D1, β-catenin, vimentin, and Slug together with decreased Src and Akt phosphorylation after fibronectin knockdown. Parallel studies in a xenograft tumor mice model further showed that tumor growth correlated well with elevation of circulating fibronectin and activation of the identified intracellular signaling molecules. The results of our study highlight a role of fibronectin in NPC cell motility and proliferation in concerted action with HIF-1α and TGF-β1 possibly through linking molecules Src and Akt. Fibronectin overexpression and autoantibody are known to have potential prognostic value in patients with NPC. Our findings shed light on the biochemical and molecular mechanisms underlying the pathogenic role of fibronectin in this disease.

The role of focal adhesion kinase in transforming growth factor-β2 induced migration of human lens epithelial cells

The migration of lens epithelial cells towards the posterior capsule is a key event in the development of posterior capsule opacification (PCO). Accumulating evidence has described crosstalk between growth factors and adhesive signaling pathways in wound healing and cell migration. The aim of the present study was to elucidate an aberrant transforming growth factor (TGF)‑β2 signaling pathway that regulated the migration of lens epithelial cells in the pathological context of PCO. The expression of fibronectin, focal adhesion kinase (FAK) and phosphorylated (p)‑FAK in HLE‑B3 cells following TGF‑β2 treatment was determined by western blot analysis and the expression of integrin α5β1 was detected by flow cytometry. Cell migration capacity was measured by wound healing and Transwell assays in the presence of 1,2,4,5‑tetraaminobenzene tetrahydrochloride, a selective FAK inhibitor, fibronectin small interfering RNA interference, arginylglycylaspartic acid peptides or α5β1‑integrin neutralizing antibodies. The 1,2,4,5‑tetraaminobenzene tetrahydrochloride was administered daily to 16 rabbits following cataract surgery. Fibronectin and TGF‑β expression were increased in the PCO group, demonstrated by immunofluorescence assays. PCO grading was conducted by slit‑lamp biomicroscopy and evaluation of posterior capsule opacification software. It was observed that TGF‑β2 promoted HLE‑B3 cell migration and upregulated fibronectin expression, which was followed by an increased phosphorylation of FAK. In addition, TGF‑β2 treatment and fibronectin surface coating significantly increased cell migration and FAK activation, which was inhibited by disrupting fibronectin‑integrin α5β1 interaction with the arginylglycylaspartic acid peptide, α5β1‑integrin neutralizing antibody or fibronectin depletion. Finally, suppression of FAK signaling by its inhibitor significantly decreased cell migration in vitro and attenuated PCO development in vivo. In summary, TGF‑β2 was indicated to promote the migration of lens epithelial cells through the TGF‑β2/fibronectin/integrin/FAK axis. Inhibition of FAK activity decreased TGF‑β2‑mediated cell migration in vitro and improved the symptoms of PCO in a rabbit model.

Mechanisms and context underlying the role of autophagy in cancer metastasis

Macroautophagy/autophagy is a fundamental cellular degradation mechanism that maintains cell homeostasis, regulates cell signaling, and promotes cell survival. Its role in promoting tumor cell survival in stress conditions is well characterized, and makes autophagy an attractive target for cancer therapy. Emerging research indicates that autophagy also influences cancer metastasis, which is the primary cause of cancer-associated mortality. However, data demonstrate that the regulatory role of autophagy in metastasis is multifaceted, and includes both metastasis-suppressing and -promoting functions. The metastasis-suppressing functions of autophagy, in particular, have important implications for autophagy-based treatments, as inhibition of autophagy may increase the risk of metastasis. In this review, we discuss the mechanisms and context underlying the role of autophagy in metastasis, which include autophagy-mediated regulation of focal adhesion dynamics, integrin signaling and trafficking, Rho GTPase-mediated cytoskeleton remodeling, anoikis resistance, extracellular matrix remodeling, epithelial-to-mesenchymal transition signaling, and tumor-stromal cell interactions. Through this, we aim to clarify the context-dependent nature of autophagy-mediated metastasis and provide direction for further research investigating the role of autophagy in cancer metastasis.

SPP1 promotes ovarian cancer progression via Integrin β1/FAK/AKT signaling pathway

OBJECTIVES

Ovarian cancer is one of the most lethal malignant tumors in women. Secreted phosphoprotein 1 (SPP1) plays an important role in some cancer types. Therefore, the role of SPP1 in ovarian cancer was determined and the potential mechanism was elucidated.

MATERIALS AND METHODS

The expression of SPP1 in ovarian cancer was determined by immunohistochemistry in ovarian cancer tissues and normal ovarian tissues. Cellular proliferation, migration, and invasion were determined by cell counting kit-8 assay, wound healing assay, and Matrigel invasion assay in SKOV3 and A2780 cells. The protein expression of SPP1, integrin subunit β1 (Integrin β1), focal adhesion kinase (FAK), and phosphorylation protein kinase B (p-AKT) was detected by Western blotting in SKOV3 cells after silencing SPP1. The expression of SPP1 was determined in SKOV3 cells after transfecting with miR-181a mimics or inhibitors. The growth of SKOV3 cells in vivo was determined in a nude mouse model of ovarian cancer after silencing SPP1.

RESULTS

The expression of SPP1 was higher in epithelial ovarian cancer tissues than in normal ovarian tissues. Silencing SPP1 decreased the cell proliferation, migration, and invasion. Ectopic expression of SPP1 increased the cell proliferation, migration, and invasion. Silencing SPP1 prevented ovarian cancer growth in mice. Silencing SPP1 inhibited Integrin β1/FAK/AKT pathway. In agreement, ectopically expressed SPP1 activated Integrin β1/FAK/AKT pathway. Also, SPP1 was regulated by miR-181a.

CONCLUSION

SPP1 is a biomarker for the prognosis of ovarian cancer. It is also oncogenic and a potential target for ovarian cancer therapy.

Exome analysis of carotid body tumor

Background

Carotid body tumor (CBT) is a form of head and neck paragangliomas (HNPGLs) arising at the bifurcation of carotid arteries. Paragangliomas are commonly associated with germline and somatic mutations involving at least one of more than thirty causative genes. However, the specific functionality of a number of these genes involved in the formation of paragangliomas has not yet been fully investigated.

Methods

Exome library preparation was carried out using Nextera® Rapid Capture Exome Kit (Illumina, USA). Sequencing was performed on NextSeq 500 System (Illumina).

Results

Exome analysis of 52 CBTs revealed potential driver mutations (PDMs) in 21 genes: ARNT, BAP1, BRAF, BRCA1, BRCA2, CDKN2A, CSDE1, FGFR3, IDH1, KIF1B, KMT2D, MEN1, RET, SDHA, SDHB, SDHC, SDHD, SETD2, TP53BP1, TP53BP2, and TP53I13. In many samples, more than one PDM was identified. There are also 41% of samples in which we did not identify any PDM; in these cases, the formation of CBT was probably caused by the cumulative effect of several not highly pathogenic mutations. Estimation of average mutation load demonstrated 6–8 mutations per megabase (Mb). Genes with the highest mutation rate were identified.

Conclusions

Exome analysis of 52 CBTs for the first time revealed the average mutation load for these tumors and also identified potential driver mutations as well as their frequencies and co-occurrence with the other PDMs.

Electronic supplementary material

The online version of this article (10.1186/s12920-018-0327-0) contains supplementary material, which is available to authorized users.

MARCKS contributes to stromal cancer-associated fibroblast activation and facilitates ovarian cancer metastasis

The Cancer Genome Atlas network has revealed that the 'mesenchymal' epithelial ovarian cancer (EOC) subtype represents the poorest outcome, indicating a crucial role of stromal cancer-associated fibroblasts (CAFs) in disease progression. The cooperative role of CAFs in EOC metastasis has long been recognized, but the mechanisms of stromal CAFs activation are still obscure. Therefore, we carried out an integrative analysis to identify the regulator genes that are responsible for CAFs activation in microdissected tumor stroma profiles. Here, we determined that myristoylated alanine-rich C-kinase substrate (MARCKS) was highly expressed in ovarian stroma, and was required for the differentiation and tumor promoting function of CAFs. Suppression of MARCKS resulted in the loss of CAF features, and diminished role of CAFs in supporting tumor cell growth in 3D organotypic cultures and in murine xenograft model. Mechanistically, we found that MARCKS maintained CAF activation through suppression of cellular senescence and activation of the AKT/Twist1 signaling. Moreover, high MARCKS expression was associated with poor patient survival in EOC. Collectively, our findings identify the potential of MARCKS inhibition as a novel stroma-oriented therapy in EOC.

Fibrotic microenvironment promotes the metastatic seeding of tumor cells via activating the fibronectin 1/secreted phosphoprotein 1-integrin signaling

The seeding of tumor cells is a critical step in the process of metastasis, but whether and how the microenvironment of target organs affects metastatic seeding remain largely unknown. Based on cell and mouse models, we found that the metastatic seeding and outgrowth of tumor cells were significantly enhanced in fibrotic lungs. The conditioned medium from both fibrotic lungs and the fibrotic lung-derived fibroblasts (CM-FLF) had a strong activity to chemoattract tumor cells and to inhibit the apoptosis of tumor cells. Subsequent investigations revealed that the levels of fibronectin 1 (FN1) and secreted phosphoprotein 1 (SPP1) were significantly increased in fibrotic lungs. Silencing of FN1 in the fibrotic lung-derived fibroblasts dramatically decreased the chemoattracting activity of CM-FLF, while silencing of FN1 or SPP1 in fibroblasts attenuated the anti-apoptosis activity of CM-FLF. Moreover, the CM-FLF-induced apoptosis resistance or chemotaxis of tumor cells was attenuated when ITGAV, the common receptor of FN1 and SPP1, was silenced by RNA interference or blocked by GRGDS treatment in tumor cells. Consistently, ITGAV silencing or GRGDS treatment significantly inhibited the seeding and outgrowth of tumor cells in fibrotic lungs in vivo. Collectively, we suggest that fibrotic microenvironment may enhance the metastatic seeding of tumor cells in the lung by chemoattracting tumor cells and inhibiting their apoptosis via activating the FN1/SPP1-ITGAV signaling. These findings give a novel insight into the regulatory mechanisms of cancer metastasis and provide a potential target for anti-metastasis therapy.

Aryl hydrocarbon receptor nuclear translocator (ARNT) isoforms control lymphoid cancer cell proliferation through differentially regulating tumor suppressor p53 activity

The aryl hydrocarbon receptor nuclear translocator (ARNT) is involved in xenobiotic and hypoxic responses, and we previously showed that ARNT also regulates nuclear factor-κB (NF-κB) signaling by altering the DNA binding activity of the RelB subunit. However, our initial study of ARNT-mediated RelB modulation was based on simultaneous suppression of the two ARNT isoforms, isoform 1 and 3, and precluded the examination of their individual functions. We find here that while normal lymphocytes harbor equal levels of isoform 1 and 3, lymphoid malignancies exhibit a shift to higher levels of ARNT isoform 1. These elevated levels of ARNT isoform 1 are critical to the proliferation of these cancerous cells, as suppression of isoform 1 in a human multiple myeloma (MM) cell line, and an anaplastic large cell lymphoma (ALCL) cell line, triggered S-phase cell cycle arrest, spontaneous apoptosis, and sensitized cells to doxorubicin treatment. Furthermore, co-suppression of RelB or p53 with ARNT isoform 1 prevented cell cycle arrest and blocked doxorubicin induced apoptosis. Together our findings reveal that certain blood cancers rely on ARNT isoform 1 to potentiate proliferation by antagonizing RelB and p53-dependent cell cycle arrest and apoptosis. Significantly, our results identify ARNT isoform 1 as a potential target for anticancer therapies.

Diallyl trisulfide inhibits cell migration and invasion of human melanoma a375 cells via inhibiting integrin/facal adhesion kinase pathway

Melanoma is the leading cause of death from skin disease due to its propensity for metastasis. Studies have shown that integrin-mediated focal adhesion kinase (FAK) signal pathway is implicated in cell proliferation, survival and metastasis of tumor cells. Our previous results indicated that diallyl trisulfide (DATS) provided its antimelanoma activity via inducing cell cycle arrest and apoptosis. The aim of this study was to explore DATS mediated antimetastatic effect and the corresponding mechanism in human melanoma A375 cells. We found that DATS exhibited an inhibitory effect on the abilities of migration and invasion in A375 cells under noncytotoxic concentrations analyzed by wound healing assays and Matrigel invasion chamber system. DATS attenuated invasion of A375 cells with characteristic of decreased activities and protein expressions of matrix metalloproteinase-2 (MMP-2) and MMP-9. Moreover, DATS exerted an inhibitory effect on cell adhesion of A375 cells, which is in correlation with the change in integrin signaling pathway. Results of Western blotting showed that DATS decreased the levels of several integrin subunits, including α4, α5, αv, β1, β3 and β4. Subsequently, DATS induced a strong decrease in total FAK, phosphorylated FAK Tyr-397,-576, -577, and disorganized F-actin stress fibers, resulting in a nonmigratory phenotype. These results suggest that the antimetastatic potential of DATS for human melanoma cells might be due to the disruption of integrin/FAK signaling pathway.

Reprogramming of stromal fibroblasts by SNAI2 contributes to tumor desmoplasia and ovarian cancer progression

BACKGROUND

Molecular profiling in ovarian cancer (OC) revealed that the desmoplasia subtype presented the poorest prognosis, highlighting the contribution of stromal fibroblasts in tumor progression. This study aimed to investigate the molecular characteristics of SNAI2 driving the transcriptional reprogramming of fibroblasts within tumors.

METHODS

SNAI2 expression was evaluated in microdissected profiles of various cancers and in various molecular subtypes of OC. Gene set enrichment analysis (GSEA) and single sample GSEA (ssGSEA) were performed to explore the correlation between SNAI2 and stromal fibroblast activation. The SNAI2 defined signature in the mesenchymal OC subtype was identified through an integrative analysis of the TCGA and the Tothill datasets. The predictive value of this signature was validated in independent datasets. SNAI2 expression alteration influence of tumor growth in primary CAFs was evaluated in 3D organotypic and murine xenograft models.

RESULTS

We demonstrated that SNAI2 was frequently activated in the tumor stroma, correlated with fibroblast activation and worse patient outcome in OC. SNAI2 transformed normal fibroblasts to a CAF-like state and boosted their tumor-supporting role in 3D organotypic culture and in OC xenograft model. SNAI2 drove a transcriptional signature in the mesenchymal subtype of OC that contributed to tumor desmoplasia, which fed back to increase SNAI2 expression and sustain fibroblast activation.

CONCLUSIONS

Our results address the role of SNAI2 in reprogramming stromal fibroblasts. The identified SNAI2 mesenchymal signature has both a predictive value and biological relevance and might be a therapeutic target for stroma-oriented therapy against the desmoplasia OC subtype.

Oleic acid-induced ANGPTL4 enhances head and neck squamous cell carcinoma anoikis resistance and metastasis via up-regulation of fibronectin

Obese patients have higher levels of free fatty acids (FFAs) in their plasma and a higher risk of cancer than their non-obese counterparts. However, the mechanisms involved in the regulation of cancer metastasis by FFAs remain unclear. In this study, we found that oleic acid (OA) induced angiopoietin-like 4 (ANGPTL4) protein expression and secretion and conferred anoikis resistance to head and neck squamous cell carcinomas (HNSCCs). The autocrine production of OA-induced ANGPTL4 further promoted HNSCC migration and invasion. In addition, the expression of peroxisome proliferator-activated receptor (PPAR) was essential for the OA-induced ANGPTL4 expression and invasion. The levels of OA-induced epithelial-mesenchymal transition markers, such as vimentin, MMP-9, and fibronectin and its downstream effectors Rac1/Cdc42, were significantly reduced in ANGPTL4-depleted cells. Knocking down fibronectin inhibited the expression of MMP-9 and repressed OA- and recombinant ANGPTL4-induced HNSCC invasion. On the other hand, ANGPTL4 siRNA inhibited OA-induced MMP-9 expression, which was reversed in fibronectin-overexpressing cells. Furthermore, the depletion of ANGPTL4 impeded the OA-primed metastatic seeding of tumor cells in the lungs. These results demonstrate that OA enhances HNSCC metastasis through the ANGPTL4/fibronectin/Rac1/Cdc42 and ANGPTL4/fibronectin/MMP-9 signaling axes.

Migration Suppression of Small Cell Lung Cancer by Polysaccharides from Nostoc commune Vaucher

Nostoc commune Vauch., classified into cyanobacteria, has been always well appreciated as a healthy food and medicine worldwide owing to its rich nutrition and potent bioactivities. Nevertheless, the inhibitory effect of polysaccharides from N. commune Vauch. (NVPS) against cancer cell progression and metastasis is still being unraveled. The results in this study showed that NVPS remarkably suppressed cell migration through blocking the epithelial-mesenchymal transition program in NCI-H446 and NCI-H1688 human small cell lung cancer cells. The inhibitory effects were attributed to the suppression of integrin β1/FAK signaling through regulating cell-matrix adhesion. Furthermore, NVPS treatment could increase E-cadherin expression, but down-regulate N-cadherin, Vimentin, and MMP-9 expression, which resulted in the blockage of STAT3 nuclear translocation and JAK1 signaling. These findings suggest that NVPS may be a good candidate for development as a possible antitumor agent against small cell lung cancer.

β1 Integrins as Therapeutic Targets to Disrupt Hallmarks of Cancer

Integrins belong to a large family of αβ heterodimeric transmembrane proteins first recognized as adhesion molecules that bind to dedicated elements of the extracellular matrix and also to other surrounding cells. As important sensors of the cell microenvironment, they regulate numerous signaling pathways in response to structural variations of the extracellular matrix. Biochemical and biomechanical cues provided by this matrix and transmitted to cells via integrins are critically modified in tumoral settings. Integrins repertoire are subjected to expression level modifications, in tumor cells, and in surrounding cancer-associated cells, implicated in tumor initiation and progression as well. As critical players in numerous cancer hallmarks, defined by Hanahan and Weinberg (2011), integrins represent pertinent therapeutic targets. We will briefly summarize here our current knowledge about integrin implications in those different hallmarks focusing primarily on β1 integrins.