Dysregulation of Rho GTPases in Human Cancers

Zearalenone promotes endometrial cancer cell migration and invasion via activation of estrogen receptor-mediated Rho/ROCK/PMLC signaling pathway

Zearalenone (ZEA), has emerged as a potential endocrine-disrupting chemical (EDC). Previous results show ZEA effects on endometrial stromal cell apoptosis, migration, and growth of endometriosis. Despite the reported presence of ZEA in Endometrial Cancer (EC) patient's blood and tissues, ZEA-induced EC promotion and its mechanism/s remain elusive. In this study, Ishikawa cells were used to investigate the ZEA effects on Ishikawa cell migration, invasion, and the underlying mechanism involved in these events. Ishikawa cells were exposed to low concentrations of ZEA (5, 25, and 125 nM) for 48 h, and morphological alterations, migration, invasion, markers associated with epithelial-mesenchymal transition (EMT), E-cadherin, Vimentin, RhoA/ROCK/PMLC pathway activation were analyzed. ZEA (25 nM) exposure caused morphological alterations like stress fiber, filopodia formation, loss of cell adhesion, and a significant increase in migration and invasive potential in extracellular matrix-coated porous membranes. Moreover, ZEA exposure also increases the Rho-GTPase activity and expression of pathway mediators, GEFH1, RhoA, ROCK1+2, CDC42, and PMLC/MLC. Furthermore, pre-treatment with specific pharmacological inhibitors for Estrogen receptor-alpha (ER-α) and ROCK attenuate the ZEA-induced stress fiber formation and altered expression of E-cadherin, Vimentin, and Rho/ROCK/PMLC pathway mediators. These findings suggest that Rho/ROCK/PMLC signaling pathways are involved in ZEA-induced Ishikawa cell migration and invasion.

Upregulation of ARHGAP9 is correlated with poor prognosis and immune infiltration in clear cell renal cell carcinoma

Rho GTPase activating protein (ARHGAP) family genes play critical roles in the onset and progression of human cancer. Rho GTPase activating protein 9 (ARHGAP9) is upregulated in various tumors. However, far too little attention has been paid to the prognostic value of ARHGAP9 and correlation with immune infiltration in clear cell renal cell carcinoma (ccRCC). Our aim is to evaluate the prognostic significance of ARHGAP9 expression and its correlation with immune infiltration in ccRCC. Transcriptional expression profiles of ARHGAP9 between ccRCC tissues and normal tissues were downloaded from The Cancer Genome Atlas. The ARHGAP9 protein expression was assessed by the Clinical Proteomic Tumor Analysis Consortium. Receiver operating characteristic curve was used to differentiate ccRCC from adjacent normal tissues. The Kaplan-Meier method was conducted to assess the effect of ARHGAP9 on survival. Protein-protein interaction networks were constructed by the STRING. Functional enrichment analyses were performed using the "ClusterProfiler" package. The immune infiltration patterns were evaluated via the tumor immune estimation resource 2.0 and Tumor-Immune System Interaction Database. ARHGAP9 expression was substantially higher in ccRCC tissues than in adjacent normal tissues. Increased ARHGAP9 mRNA expression was shown to be linked to high TNM stage and lymph node metastases. The diagnostic value of ARHGAP9 gene expression data was assessed using receiver operating characteristic curve analysis. The survival analysis module of GEPIA2 and the Kaplan-Meier plotter both showed ccRCC patients with high-ARHGAP9 had a worse prognosis than those with low-ARHGAP9. Correlation analysis indicated ARHGAP9 mRNA expression was significantly correlated with tumor purity and immune infiltrates. These findings demonstrate that upregulated ARHGAP9 indicates poor prognosis and immune infiltration in ccRCC. The current findings suggest that ARHGAP9 can be an effective biomarker and potential therapeutic strategy for ccRCC.

A multiscale functional map of somatic mutations in cancer integrating protein structure and network topology

A major goal of cancer biology is to understand the mechanisms underlying tumorigenesis driven by somatically acquired mutations. Two distinct types of computational methodologies have emerged: one focuses on analyzing clustering of mutations within protein sequences and 3D structures, while the other characterizes mutations by leveraging the topology of protein-protein interaction network. Their insights are largely non-overlapping, offering complementary strengths. Here, we established a unified, end-to-end 3D structurally-informed protein interaction network propagation framework, NetFlow3D, that systematically maps the multiscale mechanistic effects of somatic mutations in cancer. The establishment of NetFlow3D hinges upon the Human Protein Structurome, a comprehensive repository we compiled that incorporates the 3D structures of every single protein as well as the binding interfaces of all known protein interactions in humans. NetFlow3D leverages the Structurome to integrate information across atomic, residue, protein and network levels: It conducts 3D clustering of mutations across atomic and residue levels on protein structures to identify potential driver mutations. It then anisotropically propagates their impacts across the protein interaction network, with propagation guided by the specific 3D structural interfaces involved, to identify significantly interconnected network "modules", thereby uncovering key biological processes underlying disease etiology. Applied to 1,038,899 somatic protein-altering mutations in 9,946 TCGA tumors across 33 cancer types, NetFlow3D identified 1,4444 significant 3D clusters throughout the Human Protein Structurome, of which ~55% would not have been found if using only experimentally-determined structures. It then identified 26 significantly interconnected modules that encompass ~8-fold more proteins than applying standard network analyses. NetFlow3D and our pan-cancer results can be accessed from http://netflow3d.yulab.org.

The effect of HYPE knock-out on the AMPylome of human OSU-CLL leukemia cells

In humans, AMPylation of cellular proteins is carried out by Huntingtin yeast-interacting protein E (HYPE), activated under conditions of endoplasmic reticulum stress, such as in cancer cells. Extracts of the human chronic lymphocytic leukemia cell line, OSU-CLL, were fractionated using immuno-precipitation with antibodies against adenosine-phosphate and then AMP-Tyr. The proteins isolated were modified with AMP, the 'AMPylome.' AMP-labelled peptides isolated from HYPE wild-type (WT) and HYPE knock-out (KO) cells were identified using tandem mass spectrometry. A total of 213 proteins were identified from WT cell extracts, while only 23 of these were pulled down from KO cells, consistent with the presence of another AMPylator, besides HYPE. The KO cells were more sensitive to fludarabine nucleoside (2-FaraA) than WT cells. Ingenuity Pathway Analysis of the AMPylated proteins identified in WT cells clustered actin binding proteins of the cytoskeleton, and proteins of the RHO GTPase pathway that would jointly stimulate cell proliferation.

A Systems Biology Approach Unveils a Critical Role of DPP4 in Upper Gastrointestinal Cancer Patient Outcomes

Gastrointestinal (GI) cancers comprise of cancers that affect the digestive system and its accessory organs. The late detection and poor prognosis of GI cancer emphasizes the importance of identifying reliable and precise biomarkers for early diagnosis and prediction of prognosis. The membrane-bound glycoprotein dipeptidyl-peptidase 4 (DPP4), also known as CD26, is ubiquitously expressed and has a wide spectrum of biological roles. The role of DPP4/CD26 in tumor progression in different types of cancers remains elusive. However, the link between DPP4 and tumor-infiltrating cells, as well as its prognostic significance in malignancies, still require further investigation. This study was intended to elucidate the correlation of DPP4 expression and survival along with prognosis, followed by its associated enriched molecular pathways and immune cell marker levels in upper GI cancers. Results demonstrated a strong correlation between increased DPP4 expression and a worse prognosis in esophageal and gastric cancer and the co-expressed common genes with DPP4 were associated with crucial molecular pathways involved in tumorigenesis. Additionally, DPP4 was shown to be significantly linked to several immune infiltrating cell marker genes, including Macrophages (M1, M2 and Tumor Associated Macrophages), neutrophils, Treg, T-cell exhaustion, Th1 and Th2. Overall, our findings suggest that DPP4 may serve as a substantial prognostic biomarker, a possible therapeutic target, as well as it can play a critical role in the regulation of immune cell invasion in patients with gastroesophageal (esophageal, gastroesophageal junction and gastric) cancer. KEY WORDS: DPP4, integrated analysis, GI cancer, gastroesophageal cancer, gastroesophageal junction, prognosis.

Rac2 mediate foam cell formation and associated immune responses in THP-1 to promote the process of atherosclerotic plaques

Macrophages play an important role in the pathogenesis of atherosclerosis (AS) by mediating oxidative stress, inflammation and lipid metabolism, which can lead to the formation of vascular plaque. The Rac family isoforms of small molecules GTPase are active by binding to GTPase, but are inactivated by binding to GDP, and play a role in the switch of cell information conduction. This experiment adopts shRNA interference THP-1 cells respectively each subtype expression and inhibiting Rac1, Rac2, Rac3 activity, each subtype of Rac family on lipid metabolism, inflammatory reaction and oxidative stress. THP-1 cells were stimulated with Ox-LDL to establish AS cell models including lipid loading, adhesion, migration and chemotaxis. Oil Red O staining, cell immunofluorescence, scratching test, transwell, Western blot and other experiments were performed. To observe the different effects of three subtypes of Rac family on multiple links in the foaming process of THP-1 cells. ApoE-/- mice on a high-fat diet were used as animal models to examine the effects of Rac subtypes in vivo. The results showed that the activation of immune cells induced by ox-LDL was inhibited when Rac1, Rac2 and Rac3 in THP-1 were decreased, respectively. Thus, Rac1 and Rac3 act in combination with ox-LDL and are associated with cellular oxidative stress and inflammation. This study provides new means and ideas for finding potential intervention targets that have important regulatory effects on atherosclerosis, and provides a new direction for the development of clinical drugs.

ADP-Ribosylation Factor 6 Pathway Acts as a Key Executor of Mesenchymal Tumor Plasticity

Despite the "big data" on cancer from recent breakthroughs in high-throughput technology and the development of new therapeutic modalities, it remains unclear as to how intra-tumor heterogeneity and phenotypic plasticity created by various somatic abnormalities and epigenetic and metabolic adaptations orchestrate therapy resistance, immune evasiveness, and metastatic ability. Tumors are formed by various cells, including immune cells, cancer-associated fibroblasts, and endothelial cells, and their tumor microenvironment (TME) plays a crucial role in malignant tumor progression and responses to therapy. ADP-ribosylation factor 6 (ARF6) and AMAP1 are often overexpressed in cancers, which statistically correlates with poor outcomes. The ARF6-AMAP1 pathway promotes the intracellular dynamics and cell-surface expression of various proteins. This pathway is also a major target for KRAS/TP53 mutations to cooperatively promote malignancy in pancreatic ductal adenocarcinoma (PDAC), and is closely associated with immune evasion. Additionally, this pathway is important in angiogenesis, acidosis, and fibrosis associated with tumor malignancy in the TME, and its inhibition in PDAC cells results in therapeutic synergy with an anti-PD-1 antibody in vivo. Thus, the ARF6-based pathway affects the TME and the intrinsic function of tumors, leading to malignancy. Here, we discuss the potential mechanisms of this ARF6-based pathway in tumorigenesis, and novel therapeutic strategies.

Fascin-1 in Cancer Cell Metastasis: Old Target-New Insights

As metastasis is responsible for most cancer-related deaths, understanding the cellular and molecular events that lead to cancer cell migration and invasion will certainly provide insights into novel anti-metastatic therapeutic targets. Fascin-1 is an actin-bundling protein fundamental to all physiological or pathological processes that require cell migration. It is responsible for cross-linking actin microfilaments during the formation of actin-rich cellular structures at the leading edge of migrating cells such as filopodia, lamellipodia and invadopodia. While most epithelial tissues express low levels of Fascin-1, it is dramatically elevated in the majority of cancers and its expression has been associated with more aggressive disease and decreased overall survival. Hence, it has been proposed as a potential anti-cancer target. In the present review, we studied recent literature with regard to Fascin-1 expression in different cancers, its role in altering the mechanical properties of cancer cells, promoting cancer cell migration, invasion and metastasis and the effect of its inhibition, via various pharmacological inhibitors, in eliminating metastasis in vitro and/or in vivo. Recent studies corroborate the notion that Fascin-1 is critically involved in metastasis and prove that it is a valuable anti-metastatic target that is worth investigating further.

PLEKHG5 is stabilized by HDAC2-related deacetylation and confers sorafenib resistance in hepatocellular carcinoma

Sorafenib is the first FDA-approved first-line targeted drug for advanced HCC. However, resistance to sorafenib is frequently observed in clinical practice, and the molecular mechanism remains largely unknown. Here, we found that PLEKHG5 (pleckstrin homology and RhoGEF domain containing G5), a RhoGEF, was highly upregulated in sorafenib-resistant cells. PLEKHG5 overexpression activated Rac1/AKT/NF-κB signaling and reduced sensitivity to sorafenib in HCC cells, while knockdown of PLEKHG5 increased sorafenib sensitivity. The increased PLEKHG5 was related to its acetylation level and protein stability. Histone deacetylase 2 (HDAC2) was found to directly interact with PLEKHG5 to deacetylate its lysine sites within the PH domain and consequently maintain its stability. Moreover, knockout of HDAC2 (HDAC2 KO) or selective HDAC2 inhibition reduced PLEKHG5 protein levels and thereby enhanced the sensitivity of HCC to sorafenib in vitro and in vivo, while overexpression of PLEKHG5 in HDAC2 KO cells reduced the sensitivity to sorafenib. Our work showed a novel mechanism: HDAC2-mediated PLEKHG5 posttranslational modification maintains sorafenib resistance. This is a proof-of-concept study on targeting HDAC2 and PLEKHG5 in sorafenib-treated HCC patients as a new pharmaceutical intervention for advanced HCC.

Advances in the development of Rho GTPase inhibitors

Rho guanosine triphosphatases (Rho GTPases), as members of the Ras superfamily, are GDP/GTP binding proteins that behave as molecular switches for the transduction of signals from external stimuli. Rho GTPases play essential roles in a number of cellular processes including cell cycle, cell polarity as well as cell migration. The dysregulations of Rho GTPases are related with various diseases, especially with cancers. Accumulating evidence supports that Rho GTPases play important roles in cancer development and progression. Rho GTPases become potential therapeutic targets for cancer therapy. And a number of inhibitors targeting Rho GTPases have been developed. In this review, we discuss their structural features, summarize their roles in cancer, and focus on the recent progress of their inhibitors, which are beneficial for the drug discovery targeting Rho GTPases.

p73 activates transcriptional signatures of basal lineage identity and ciliogenesis in pancreatic ductal adenocarcinoma

During the progression of pancreatic ductal adenocarcinoma (PDAC), tumor cells are known to acquire transcriptional and morphological properties of the basal (also known as squamous) epithelial lineage, which leads to more aggressive disease characteristics. Here, we show that a subset of basal-like PDAC tumors aberrantly express p73 (TA isoform), which is a known transcriptional activator of basal lineage identity, ciliogenesis, and tumor suppression in normal tissue development. Using gain- and loss- of function experiments, we show that p73 is necessary and sufficient to activate genes related to basal identity (e.g. KRT5), ciliogenesis (e.g. FOXJ1), and p53-like tumor suppression (e.g. CDKN1A) in human PDAC models. Owing to the paradoxical combination of oncogenic and tumor suppressive outputs of this transcription factor, we propose that PDAC cells express a low level of p73 that is optimal for promoting lineage plasticity without severe impairment of cell proliferation. Collectively, our study reinforces how PDAC cells exploit master regulators of the basal epithelial lineage during disease progression.

The potential therapeutic roles of Rho GTPases in substance dependence

Rho GTPases family are considered to be molecular switches that regulate various cellular processes, including cytoskeleton remodeling, cell polarity, synaptic development and maintenance. Accumulating evidence shows that Rho GTPases are involved in neuronal development and brain diseases, including substance dependence. However, the functions of Rho GTPases in substance dependence are divergent and cerebral nuclei-dependent. Thereby, comprehensive integration of their roles and correlated mechanisms are urgently needed. In this review, the molecular functions and regulatory mechanisms of Rho GTPases and their regulators such as GTPase-activating proteins (GAPs) and guanine nucleotide exchange factors (GEFs) in substance dependence have been reviewed, and this is of great significance for understanding their spatiotemporal roles in addictions induced by different addictive substances and in different stages of substance dependence.

Characterization of Novel Derivatives of MBQ-167, an inhibitor of the GTP-binding proteins Rac/Cdc42

Rac and Cdc42, are homologous GTPases that regulate cell migration, invasion, and cell cycle progression; thus, representing key targets for metastasis therapy. We previously reported on the efficacy of MBQ-167, which blocks both Rac1 and Cdc42 in breast cancer cells and mouse models of metastasis. To identify compounds with increased activity, a panel of MBQ-167 derivatives was synthesized, maintaining its 9-ethyl-3-(1H-1,2,3-triazol-1-yl)-9H-carbazole core. Similar to MBQ-167, MBQ-168 and EHop-097, inhibit activation of Rac and Rac1B splice variant and breast cancer cell viability, and induce apoptosis. MBQ-167 and MBQ-168 inhibit Rac and Cdc42 by interfering with guanine nucleotide binding, and MBQ-168 is a more effective inhibitor of PAK (1,2,3) activation. EHop-097 acts via a different mechanism by inhibiting the interaction of the guanine nucleotide exchange factor (GEF) Vav with Rac. MBQ-168 and EHop-097 inhibit metastatic breast cancer cell migration, and MBQ-168 promotes loss of cancer cell polarity to result in disorganization of the actin cytoskeleton and detachment from the substratum. In lung cancer cells, MBQ-168 is more effective than MBQ-167 or EHop-097 at reducing ruffle formation in response to EGF. Comparable to MBQ-167, MBQ-168 significantly inhibits HER2+ tumor growth and metastasis to lung, liver, and spleen. Both MBQ-167 and MBQ-168 inhibit the cytochrome P450 (CYP) enzymes 3A4, 2C9, and 2C19. However, MBQ-168 is ~10X less potent than MBQ-167 at inhibiting CYP3A4, thus demonstrating its utility in relevant combination therapies. In conclusion, the MBQ-167 derivatives MBQ-168 and EHop-097 are additional promising anti metastatic cancer compounds with similar and distinct mechanisms.

RHO GTPase family in hepatocellular carcinoma

RHO GTPases are a subfamily of the RAS superfamily of proteins, which are highly conserved in eukaryotic species and have important biological functions, including actin cytoskeleton reorganization, cell proliferation, cell polarity, and vesicular transport. Recent studies indicate that RHO GTPases participate in the proliferation, migration, invasion and metastasis of cancer, playing an essential role in the tumorigenesis and progression of hepatocellular carcinoma (HCC). This review first introduces the classification, structure, regulators and functions of RHO GTPases, then dissects its role in HCC, especially in migration and metastasis. Finally, we summarize inhibitors targeting RHO GTPases and highlight the issues that should be addressed to improve the potency of these inhibitors.

MLL regulates the actin cytoskeleton and cell migration by stabilising Rho GTPases via the expression of RhoGDI1

Attainment of proper cell shape and the regulation of cell migration are essential processes in the development of an organism. The mixed lineage leukemia (MLL or KMT2A) protein, a histone 3 lysine 4 (H3K4) methyltransferase, plays a critical role in cell-fate decisions during skeletal development and haematopoiesis in higher vertebrates. Rho GTPases - RhoA, Rac1 and CDC42 - are small G proteins that regulate various key cellular processes, such as actin cytoskeleton formation, the maintenance of cell shape and cell migration. Here, we report that MLL regulates the homeostasis of these small Rho GTPases. Loss of MLL resulted in an abnormal cell shape and a disrupted actin cytoskeleton, which lead to diminished cell spreading and migration. MLL depletion affected the stability and activity of Rho GTPases in a SET domain-dependent manner, but these Rho GTPases were not direct transcriptional targets of MLL. Instead, MLL regulated the transcript levels of their chaperone protein RhoGDI1 (also known as ARHGDIA). Using MDA-MB-231, a triple-negative breast cancer cell line with high RhoGDI1 expression, we show that MLL depletion or inhibition by small molecules reduces tumour progression in nude mice. Our studies highlight the central regulatory role of MLL in Rho/Rac/CDC42 signalling pathways. This article has an associated First Person interview with the first author of the paper.

Oncogenic BRAF induces whole-genome doubling through suppression of cytokinesis

Melanomas and other solid tumors commonly have increased ploidy, with near-tetraploid karyotypes being most frequently observed. Such karyotypes have been shown to arise through whole-genome doubling events that occur during early stages of tumor progression. The generation of tetraploid cells via whole-genome doubling is proposed to allow nascent tumor cells the ability to sample various pro-tumorigenic genomic configurations while avoiding the negative consequences that chromosomal gains or losses have in diploid cells. Whereas a high prevalence of whole-genome doubling events has been established, the means by which whole-genome doubling arises is unclear. Here, we find that BRAFV600E, the most common mutation in melanomas, can induce whole-genome doubling via cytokinesis failure in vitro and in a zebrafish melanoma model. Mechanistically, BRAFV600E causes decreased activation and localization of RhoA, a critical cytokinesis regulator. BRAFV600E activity during G1/S phases of the cell cycle is required to suppress cytokinesis. During G1/S, BRAFV600E activity causes inappropriate centriole amplification, which is linked in part to inhibition of RhoA and suppression of cytokinesis. Together these data suggest that common abnormalities of melanomas linked to tumorigenesis - amplified centrosomes and whole-genome doubling events - can be induced by oncogenic BRAF and other mutations that increase RAS/MAPK pathway activity.

Transcriptomic Analysis of Canine Osteosarcoma from a Precision Medicine Perspective Reveals Limitations of Differential Gene Expression Studies

Despite significant advances in cancer diagnosis and treatment, osteosarcoma (OSA), an aggressive primary bone tumor, has eluded attempts at improving patient survival for many decades. The difficulty in managing OSA lies in its extreme genetic complexity, drug resistance, and heterogeneity, making it improbable that a single-target treatment would be beneficial for the majority of affected individuals. Precision medicine seeks to fill this gap by addressing the intra- and inter-tumoral heterogeneity to improve patient outcome and survival. The characterization of differentially expressed genes (DEGs) unique to the tumor provides insight into the phenotype and can be useful for informing appropriate therapies as well as the development of novel treatments. Traditional DEG analysis combines patient data to derive statistically inferred genes that are dysregulated in the group; however, the results from this approach are not necessarily consistent across individual patients, thus contradicting the basis of precision medicine. Spontaneously occurring OSA in the dog shares remarkably similar clinical, histological, and molecular characteristics to the human disease and therefore serves as an excellent model. In this study, we use transcriptomic sequencing of RNA isolated from primary OSA tumor and patient-matched normal bone from seven dogs prior to chemotherapy to identify DEGs in the group. We then evaluate the universality of these changes in transcript levels across patients to identify DEGs at the individual level. These results can be useful for reframing our perspective of transcriptomic analysis from a precision medicine perspective by identifying variations in DEGs among individuals.

Mechanism of Antibacterial Enhancement and Drug Resistance Based on Smart Medical Imaging on Antibiotics

With the development of antibacterial, synergistic, and drug resistance research, the requirements for the specificity of antibiotics are getting higher and higher. In the research based on the specificity of antibiotics, this article uses intelligent medical image processing methods to study the specificity of the antibacterial efficiency of nanocopper oxide and the inhibition of drug resistance. Copper oxide nanorods have the properties of surface effect, quantum size effect, volume effect, and macroscopic quantum tunneling effect. Compared with ordinary copper oxide, the nanoscale gives them special properties of electricity, optics, and catalysis. In this article, in the research based on the specificity of antibiotics, the specificity of antimicrobial efficiency and drug resistance inhibition of nanocopper oxide are studied by using smart medical information processing methods. Drug sensitivity paper tablet method is a drug sensitivity experiment to determine drug sensitivity to make accurate and effective use of drugs for treatment. Colony growth method is used to take the equivalent volume of fermentation liquid at different times to determine the content of bacteria. In this article, Staphylococcus aureus is cultivated by the drug-sensitive disk method and the colony growth method. Then, according to this type of antibiotic and bacterial group combination, Staphylococcus aureus is divided into a penicillin group, nanocopper oxide group, and cephalosporin group. 0.5 g of the corresponding antibiotic was added to each group. TMP (trimethoprim) acts as a synergist, and the ratio of TMP to antibiotic is 1 : 5. Finally, we compared the inhibitory concentration indexes of the above three groups and inferred the synergistic effect of antibiotics and the inhibitory effect of drug resistance through the specificity of the antibiotics that the antibacterial activity was further studied. The results showed that the antibacterial effect of TMP combined with nano-CuO was 38% higher than that of the penicillin group and 41% higher than that of the cephalosporin group. In addition, the combined effect of TMP and antibiotics is greater than the combined effect of TMP and antibiotics alone. From the observation of smart medical system processing, it is speculated that the reason may be that they provide each other with a suitable environment. Because of this combined effect between the TMP and the antibiotic, it can influence each other. From the results, the combined effect is 48% higher than the combined effect. Therefore, according to the results of medical imaging, the combination of antibiotics and antibacterial synergists can improve specificity and antibacterial rate.

Metastasis prevention: targeting causes and roots

The spread of tumor cells from the primary focus, metastasis, is the main cause of cancer mortality. Therefore, anticancer therapy should be focused on the prevention of metastatic disease. Key targets can be conditions in the primary tumor that are favorable for the appearance of metastatic cells and the first steps of the metastatic cascade. Here, we discuss different approaches for targeting metastasis causes (hypoxia, metabolism changes, and tumor microenvironment) and roots (angiogenesis, epithelial-mesenchymal transition, migration, and invasion). Also, we emphasize the challenges of the existing approaches for metastasis prevention and suggest opportunities to overcome them. In conclusion, we highlight the importance of clinical evaluation of the agents showing antimetastatic effects in vivo, especially in patients with early-stage cancers, the identification of metastatic seeds, and the development of therapeutics for their eradication.

Molecular neuropathology of brain-invasive meningiomas

Invasion of brain tissue by meningiomas has been identified as one key factor for meningioma recurrence. The identification of meningioma tumor tissue surrounded by brain tissue in neurosurgical samples has been touted as a criterion for atypical meningioma (CNS WHO grade 2), but is only rarely seen in the absence of other high-grade features, with brain-invasive otherwise benign (BIOB) meningiomas remaining controversial. While post-surgery irradiation therapy might be initiated in brain-invasive meningiomas to prevent recurrences, specific treatment approaches targeting key molecules involved in the invasive process are not established. Here we have compiled the current knowledge about mechanisms supporting brain tissue invasion by meningiomas and summarize preclinical models studying targeted therapies with potential inhibitory effects.

A linkage between effectual genes in progression of CRC through canonical and non-canonical TGF-β signaling pathways

Different molecular signaling pathways have been involved in the incidence and progression of CRC. We aimed to examine the correlation between eight candidate genes, including TFGβ, SMAD2, SMAD4, RhoA, EGFR, MAP2K1, MTA1, and LEF1 in the progression of colorectal cancer (CRC) and their association with clinicopathological variables and CRC patients prognosis. Immunohistochemistry and quantitative real-time polymerase chain reaction (qRT-PCR) analysis 2^-ΔΔct, were performed to assess the expression of eight genes in 64 and 122 patients with CRC, respectively and 20 normal samples were added for verification. We showed a positive correlation between SMAD2 and MAP2K1 (r = 0.337, P < 0.001), MAP2K1 and LEF1 (r = 0.187, P = 0.03), SMAD4 and RhoA (r = 0.214, P = 0.01) and as well, a negative correlation between SMAD2 and TGFβ (r =  - 0.197, P = 0.02), and RhoA and LEF1 (r =  - 0.180, P = 0.04) in tumor tissues. A decrease in RhoA mRNA expression was associated with the advanced TNM stage (P = 0.01), while the EGFR and SMAD2 mRNA expression upregulated in advanced stages (P = 0.03, P = 0.03), respectively. Also, an increase in EGFR and SMAD4 protein expression was significantly associated with the advanced TNM stage (P = 0.000) (P = .002), respectively. Perceiving the connections between canonical and non-canonical Transforming growth factor (TGF-β) signaling pathway along with the epidermal growth factor receptor (EGFR) and WNT cascades may trigger the development of novel approaches for CRC prediction.

Non-homogeneous dispersion of graphene in polyacrylonitrile substrates induces a migrastatic response and epithelial-like differentiation in MCF7 breast cancer cells

Background

Recent advances from studies of graphene and graphene-based derivatives have highlighted the great potential of these nanomaterials as migrastatic agents with the ability to modulate tumor microenvironments. Nevertheless, the administration of graphene nanomaterials in suspensions in vivo is controversial. As an alternative approach, herein, we report the immobilization of high concentrations of graphene nanoplatelets in polyacrylonitrile film substrates (named PAN/G10) and evaluate their potential use as migrastatic agents on cancer cells.

Results

Breast cancer MCF7 cells cultured on PAN/G10 substrates presented features resembling mesenchymal-to-epithelial transition, e.g., (i) inhibition of migratory activity; (ii) activation of the expression of E-cadherin, cytokeratin 18, ZO-1 and EpCAM, four key molecular markers of epithelial differentiation; (iii) formation of adherens junctions with clustering and adhesion of cancer cells in aggregates or islets, and (iv) reorganization of the actin cytoskeleton resulting in a polygonal cell shape. Remarkably, assessment with Raman spectroscopy revealed that the above-mentioned events were produced when MCF7 cells were preferentially located on top of graphene-rich regions of the PAN/G10 substrates.

Conclusions

The present data demonstrate the capacity of these composite substrates to induce an epithelial-like differentiation in MCF7 breast cancer cells, resulting in a migrastatic effect without any chemical agent-mediated signaling. Future works will aim to thoroughly evaluate the mechanisms of how PAN/G10 substrates trigger these responses in cancer cells and their potential use as antimetastatics for the treatment of solid cancers.

Graphical Abstract

RAS induced senescence of skin keratinocytes is mediated through Rho-associated protein kinase (ROCK)

Cellular senescence is a well-documented response to oncogene activation in many tissues. Multiple pathways are invoked to achieve senescence indicating its importance to counteract the transforming activities of oncogenic stimulation. We now report that the Rho-associated protein kinase (ROCK) signaling pathway is a critical regulator of oncogene-induced senescence in skin carcinogenesis. Transformation of mouse keratinocytes with oncogenic RAS upregulates ROCK activity and initiates a senescence response characterized by cell enlargement, growth inhibition, upregulation of senescence associated β-galactosidase (SAβgal) expression, and release of multiple pro-inflammatory factors comprising the senescence-associated secretory phenotype (SASP). The addition of the ROCK inhibitor Y-27632 and others prevents these senescence responses and maintains proliferating confluent RAS transformed keratinocyte cultures indefinitely. Mechanistically, oncogenic RAS transformation is associated with upregulation of cell cycle inhibitors p15Ink4b , p16Ink4a , and p19Arf and downregulation of p-AKT, all of which are reversed by Y-27632. RNA-seq analysis of Y-27632 treated RAS-transformed keratinocytes indicated that the inhibitor reduced growth-inhibitory gene expression profiles and maintained expression of proliferative pathways. Y-27632 also reduced the expression of NF-κB effector genes and the expression of IκBζ downstream mediators. The senescence inhibition from Y-27632 was reversible, and upon its removal, senescence reoccurred in vitro with rapid upregulation of cell cycle inhibitors, SASP expression, and cell detachment. Y-27632 treated cultured RAS-keratinocytes formed tumors in the absence of the inhibitor when placed in skin orthografts suggesting that factors in the tumor microenvironment can overcome the drive to senescence imparted by overactive ROCK activity.

Rho GTPase signalling networks in cancer cell transendothelial migration

Rho GTPases are small signalling G-proteins that are central regulators of cytoskeleton dynamics, and thereby regulate many cellular processes, including the shape, adhesion and migration of cells. As such, Rho GTPases are also essential for the invasive behaviour of cancer cells, and thus involved in several steps of the metastatic cascade, including the extravasation of cancer cells. Extravasation, the process by which cancer cells leave the circulation by transmigrating through the endothelium that lines capillary walls, is an essential step for metastasis towards distant organs. During extravasation, Rho GTPase signalling networks not only regulate the transmigration of cancer cells but also regulate the interactions between cancer and endothelial cells and are involved in the disruption of the endothelial barrier function, ultimately allowing cancer cells to extravasate into the underlying tissue and potentially form metastases. Thus, targeting Rho GTPase signalling networks in cancer may be an effective approach to inhibit extravasation and metastasis. In this review, the complex process of cancer cell extravasation will be discussed in detail. Additionally, the roles and regulation of Rho GTPase signalling networks during cancer cell extravasation will be discussed, both from a cancer cell and endothelial cell point of view.

Analysis of NIS Plasma Membrane Interactors Discloses Key Regulation by a SRC/RAC1/PAK1/PIP5K/EZRIN Pathway with Potential Implications for Radioiodine Re-Sensitization Therapy in Thyroid Cancer

The functional expression of the sodium-iodide symporter (NIS) at the membrane of differentiated thyroid cancer (DTC) cells is the cornerstone for the use of radioiodine (RAI) therapy in these malignancies. However, NIS gene expression is frequently downregulated in malignant thyroid tissue, and 30% to 50% of metastatic DTCs become refractory to RAI treatment, which dramatically decreases patient survival. Several strategies have been attempted to increase the NIS mRNA levels in refractory DTC cells, so as to re-sensitize refractory tumors to RAI. However, there are many RAI-refractory DTCs in which the NIS mRNA and protein levels are relatively abundant but only reduced levels of iodide uptake are detected, suggesting a posttranslational failure in the delivery of NIS to the plasma membrane (PM), or an impaired residency at the PM. Because little is known about the molecules and pathways regulating NIS delivery to, and residency at, the PM of thyroid cells, we here employed an intact-cell labeling/immunoprecipitation methodology to selectively purify NIS-containing macromolecular complexes from the PM. Using mass spectrometry, we characterized and compared the composition of NIS PM complexes to that of NIS complexes isolated from whole cell (WC) lysates. Applying gene ontology analysis to the obtained MS data, we found that while both the PM-NIS and WC-NIS datasets had in common a considerable number of proteins involved in vesicle transport and protein trafficking, the NIS PM complexes were particularly enriched in proteins associated with the regulation of the actin cytoskeleton. Through a systematic validation of the detected interactions by co-immunoprecipitation and Western blot, followed by the biochemical and functional characterization of the contribution of each interactor to NIS PM residency and iodide uptake, we were able to identify a pathway by which the PM localization and function of NIS depends on its binding to SRC kinase, which leads to the recruitment and activation of the small GTPase RAC1. RAC1 signals through PAK1 and PIP5K to promote ARP2/3-mediated actin polymerization, and the recruitment and binding of the actin anchoring protein EZRIN to NIS, promoting its residency and function at the PM of normal and TC cells. Besides providing novel insights into the regulation of NIS localization and function at the PM of TC cells, our results open new venues for therapeutic intervention in TC, namely the possibility of modulating abnormal SRC signaling in refractory TC from a proliferative/invasive effect to the re-sensitization of these tumors to RAI therapy by inducing NIS retention at the PM.

Skin Cancers and the Contribution of Rho GTPase Signaling Networks to Their Progression

Skin cancers are the most common cancers worldwide. Among them, melanoma, basal cell carcinoma of the skin and cutaneous squamous cell carcinoma are the three major subtypes. These cancers are characterized by different genetic perturbations even though they are similarly caused by a lifelong exposure to the sun. The main oncogenic drivers of skin cancer initiation have been known for a while, yet it remains unclear what are the molecular events that mediate their oncogenic functions and that contribute to their progression. Moreover, patients with aggressive skin cancers have been known to develop resistance to currently available treatment, which is urging us to identify new therapeutic opportunities based on a better understanding of skin cancer biology. More recently, the contribution of cytoskeletal dynamics and Rho GTPase signaling networks to the progression of skin cancers has been highlighted by several studies. In this review, we underline the various perturbations in the activity and regulation of Rho GTPase network components that contribute to skin cancer development, and we explore the emerging therapeutic opportunities that are surfacing from these studies.

RHO GTPases: from new partners to complex immune syndromes

Ras homology (RHO) GTPases are signalling proteins that have crucial roles in triggering multiple immune functions. Through their interactions with a broad range of effectors and kinases, they regulate cytoskeletal dynamics, cell polarity and the trafficking and proliferation of immune cells. The activity and localization of RHO GTPases are highly controlled by classical families of regulators that share consensus motifs. In this Review, we describe the recent discovery of atypical modulators and partners of RHO GTPases, which bring an additional layer of regulation and plasticity to the control of RHO GTPase activities in the immune system. Furthermore, the development of large-scale genetic screening has now enabled researchers to identify dysregulation of RHO GTPase signalling pathways as a cause of many immune system-related diseases. We discuss the mutations that have been identified in RHO GTPases and their signalling circuits in patients with rare diseases. The discoveries of new RHO GTPase partners and genetic mutations in RHO GTPase signalling hubs have uncovered unsuspected layers of crosstalk with other signalling pathways and may provide novel therapeutic opportunities for patients affected by complex immune or broader syndromes.

Several Fusion Genes Identified in a Spermatic Cord Leiomyoma With Rearrangements of Chromosome Arms 3p and 21q

BACKGROUND/AIM

Benign smooth-muscle tumors, leiomyomas, occur in nearly every organ but are most common in the uterus. Whereas much is known about the genetics of uterine leiomyomas, little genetic information exists about leiomyomas of other organs. Here, we report and discuss the genetic findings in a para-testicular leiomyoma.

MATERIALS AND METHODS

Cytogenetic, array comparative genomic hybridization (aCGH) RNA sequencing, reverse-transcription polymerase chain reaction (RT- PCR), and Sanger sequencing analyses were performed on a leiomyoma of the spermatic cord removed from a 61-year-old man.

RESULTS

The karyotype was 48~50,XY,add(3) (p21),+4,+7,+8,+9,add(21)(q22)[cp9]/46,XY[2]. aCGH confirmed the trisomies and also detected multiple gains and losses from 3p and 21q. RNA sequencing detected the chimeras ARHGEF3-CACNA2D2, TRAK1-TIMP4, ITPR1- DT-NR2C2, CLASP2-IL17RD, ZNF621-LARS2, CNTN4- RHOA, and NR2C2-CFAP410. All chimeras were confirmed by RT-PCR and Sanger sequencing.

CONCLUSION

Our data, together with those previously published, indicate that a group of leiomyomas may be cytogenetically characterized by aberrations of 3p and the formation of fusion genes.

Cytoplasmic Localization Isoform of Cyclin Y Enhanced the Metastatic Ability of Lung Cancer via Regulating Tropomyosin 4

Cyclin Y (CCNY) is a novel cyclin and highly conserved in metazoan species. Previous studies from our and other laboratory indicate that CCNY play a crucial role in tumor progression. There are two CCNY isoform which has different subcellular distributions, with cytoplasmic isoform (CCNYc) and membrane distribution isoform (CCNYm). However, the expression and function of CCNY isoforms is still unclear. We firstly found CCNYc was expressed in natural lung cancer tissue and cells through the subcellular distribution. Co-IP and immunofluorescence showed that both CCNYm and CCNYc could interact with PFTK1. Further studies illustrated that CCNYc but not CCNYm enhanced cell migration and invasion activity both in vivo and vitro. The function of CCNYc could be inhibited by suppression of PFTK1 expression. In addition, our data indicated that tropomyosin 4 (TPM4), a kind of actin-binding proteins, was down-regulated by suppression of CCNY. F-actin assembly could be controlled by CCNYc as well as PFTK1 and TPM4. As a result, CCNY was mainly expressed in lung cancer. CCNYc could promote cell motility and invasion. It indicated that CCNYc/PFTK1 complex could promote cell metastasis by regulating the formation of F-actin via TPM4.

Geranylgeraniol prevents zoledronic acid-mediated reduction of viable mesenchymal stem cells via induction of Rho-dependent YAP activation

Long-term use of zoledronic acid (ZA) increases the risk of medication-related osteonecrosis of the jaw (MRONJ). This may be attributed to ZA-mediated reduction of viable mesenchymal stem cells (MSCs). ZA inhibits protein geranylgeranylation, thus suppressing cell viability and proliferation. Geranylgeraniol (GGOH), which is a naturally found intermediate compound in the mevalonate pathway, has positive effects against ZA. However, precise mechanisms by which GGOH may help preserve stem cell viability against ZA are not fully understood. The objective of this study was to investigate the cytoprotective mechanisms of GGOH against ZA. The results showed that while ZA dramatically decreased the number of viable MSCs, GGOH prevented this negative effect. GGOH-rescued ZA-exposed MSCs formed mineralization comparable to that produced by normal MSCs. Mechanistically, GGOH preserved the number of viable MSCs by its reversal of ZA-mediated Ki67+ MSC number reduction, cell cycle arrest and apoptosis. Moreover, GGOH prevented ZA-suppressed RhoA activity and YAP activation. The results also established the involvement of Rho-dependent YAP and YAP-mediated CDK6 in the cytoprotective ability of GGOH against ZA. In conclusion, GGOH preserves a pool of viable MSCs with osteogenic potency against ZA by rescuing the activity of Rho-dependent YAP activation, suggesting GGOH as a promising agent and YAP as a potential therapeutic target for MRONJ.

Ras Homolog Family Member F, Filopodia Associated Promotes Hepatocellular Carcinoma Metastasis by Altering the Metabolic Status of Cancer Cells Through RAB3D

BACKGROUND AND AIMS

The mechanism by which tumor cells resist metabolic stress remains unclear, but many oncogenes are known to regulate this process. Accordingly, metabolic stress is closely associated with tumor metastasis. In this study, gene chip technology showed that Ras homolog family member F, filopodia associated (RHOF), a member of the Rho guanosine triphosphatase family, is an oncogene that is significantly related to hepatocellular carcinoma (HCC) metastasis; however, it has rarely been reported in tumors. Our aim was to determine the clinicopathological significance and role of RHOF in HCC progression and investigate the associated mechanisms.

APPROACH AND RESULTS

The results showed that compared to expression in adjacent noncancerous tissues, RHOF was frequently up-regulated in HCC tumor samples and elevated under conditions of glucose deprivation. RHOF expression was associated with tumor-node-metastasis stage, T grade, metastasis status, recurrence, and survival in HCC. RHOF also affected cell morphology and promoted migration, invasion, and epithelial-mesenchymal transition (EMT) of HCC cell lines. Analysis of the underlying mechanism showed that RHOF promoted the Warburg effect by up-regulating the expression and function of several glycolytic enzymes in HCC cells. This metabolic shift enhanced HCC cell migration and invasion. Specifically, RHOF exerted a tumor-promoting effect by directly interacting with AMP-activated protein kinase (AMPK) and increasing the phosphorylation of AMPK. This subsequently affected RAB3D mRNA stability and led to elevated RAB3D expression, thereby amplifying the Warburg effect and malignant biological behaviors of HCC cells.

CONCLUSIONS

RHOF helps tumor cells resist metabolic stress through modulating the Warburg effect and plays a critical role in promoting HCC cell migration, invasion, and EMT, highlighting its important role in remodeling the metastatic microenvironment and regulating tumor metastasis. RHOF shows potential as a therapeutic target and prognostic biomarker for HCC.

Cancer type-specific alterations in actin genes: Worth a closer look?

Actins form a strongly conserved family of proteins that are central to the functioning of the actin cytoskeleton partaking in natural processes such as cell division, adhesion, contraction and migration. These processes, however, also occur during the various phases of cancer progression. Yet, surprisingly, alterations in the six human actin genes in cancer studies have received little attention and the focus was mostly on deregulated expression levels of actins and even more so of actin-binding or regulatory proteins. Starting from the early mutation work in the 1980s, we propose based on reviewing literature and data from patient cancer genomes that alterations in actin genes are different in distinct cancer subtypes, suggesting some specificity. These actin gene alterations include (missense) mutations, gene fusions and copy number alterations (deletions and amplifications) and we illustrate their occurrence for a limited number of examples including actin mutations in lymphoid cancers and nonmelanoma skin cancer and actin gene copy number alterations for breast, prostate and liver cancers. A challenge in the future will be to further sort out the specificity per actin gene, alteration type and cancer subtype. Even more challenging is (experimentally) distinguishing between cause and consequence: which alterations are passengers and which are involved in tumor progression of particular cancer subtypes?

Synthesis, Molecular Docking Studies and In Silico ADMET Screening of New Heterocycles Linked Thiazole Conjugates as Potent Anti-Hepatic Cancer Agents

Thiazoles are important scaffolds in organic chemistry. Biosynthesis of thiazoles is considered to be an excellent target for the design of novel classes of therapeutic agents. In this study, a new series of 2-ethylidenehydrazono-5-arylazothiazoles 5a–d and 2-ethylidenehydrazono-5-arylazo- thiazolones 8a–d were synthesized via the cyclocondensation reaction of the appropriate hydrazonyl halides 4a–d and 7a–d with ethylidene thiosemicarbazide 3, respectively. Furthermore, the thiosemicarbazide derivative 3 was reacted with different bromoacetyl compounds 10–12 to afford the respective thiazole derivatives 13–15. Chemical composition of the novel derivatives was established on bases of their spectral data (FTIR, ¹H-NMR, ¹³C-NMR and mass spectrometry) and microanalytical data. The newly synthesized derivatives were screened for their in vitro anti-hepatic cancer potency using an MTT assay. Moreover, an in silico technique was used to assess the interaction modes of the compounds with the active site of Rho6 protein. The docking studies of the target Rho6 with the newly synthesized fourteen compounds showed good docking scores with acceptable binding interactions. The presented results revealed that the newly synthesized compounds exhibited promising inhibition activity against hepatic cancer cell lines (HepG2).

Rho Family GTPases in Cancer

This Special Issue containing seminal contributions from international experts highlights the current understanding of Rho GTPases in cancer, with an emphasis on recognizing their central importance as critical targets for cancer therapy and for chemosensitization of current therapeutic strategies [...].

The Mevalonate Pathway, a Metabolic Target in Cancer Therapy

A hallmark of cancer cells includes a metabolic reprograming that provides energy, the essential building blocks, and signaling required to maintain survival, rapid growth, metastasis, and drug resistance of many cancers. The influence of tumor microenviroment on cancer cells also results an essential driving force for cancer progression and drug resistance. Lipid-related enzymes, lipid-derived metabolites and/or signaling pathways linked to critical regulators of lipid metabolism can influence gene expression and chromatin remodeling, cellular differentiation, stress response pathways, or tumor microenviroment, and, collectively, drive tumor development. Reprograming of lipid metabolism includes a deregulated activity of mevalonate (MVA)/cholesterol biosynthetic pathway in specific cancer cells which, in comparison with normal cell counterparts, are dependent of the continuous availability of MVA/cholesterol-derived metabolites (i.e., sterols and non-sterol intermediates) for tumor development. Accordingly, there are increasing amount of data, from preclinical and epidemiological studies, that support an inverse association between the use of statins, potent inhibitors of MVA biosynthetic pathway, and mortality rate in specific cancers (e.g., colon, prostate, liver, breast, hematological malignances). In contrast, despite the tolerance and therapeutic efficacy shown by statins in cardiovascular disease, cancer treatment demands the use of relatively high doses of single statins for a prolonged period, thereby limiting this therapeutic strategy due to adverse effects. Clinically relevant, synergistic effects of tolerable doses of statins with conventional chemotherapy might enhance efficacy with lower doses of each drug and, probably, reduce adverse effects and resistance. In spite of that, clinical trials to identify combinatory therapies that improve therapeutic window are still a challenge. In the present review, we revisit molecular evidences showing that deregulated activity of MVA biosynthetic pathway has an essential role in oncogenesis and drug resistance, and the potential use of MVA pathway inhibitors to improve therapeutic window in cancer.

Regulators at Every Step-How microRNAs Drive Tumor Cell Invasiveness and Metastasis

Tumor cell invasiveness and metastasis are the main causes of mortality in cancer. Tumor progression is composed of many steps, including primary tumor growth, local invasion, intravasation, survival in the circulation, pre-metastatic niche formation, and metastasis. All these steps are strictly controlled by microRNAs (miRNAs), small non-coding RNA that regulate gene expression at the post-transcriptional level. miRNAs can act as oncomiRs that promote tumor cell invasion and metastasis or as tumor suppressor miRNAs that inhibit tumor progression. These miRNAs regulate the actin cytoskeleton, the expression of extracellular matrix (ECM) receptors including integrins and ECM-remodeling enzymes comprising matrix metalloproteinases (MMPs), and regulate epithelial-mesenchymal transition (EMT), hence modulating cell migration and invasiveness. Moreover, miRNAs regulate angiogenesis, the formation of a pre-metastatic niche, and metastasis. Thus, miRNAs are biomarkers of metastases as well as promising targets of therapy. In this review, we comprehensively describe the role of various miRNAs in tumor cell migration, invasion, and metastasis.

Regulators at Every Step—How microRNAs Drive Tumor Cell Invasiveness and Metastasis

Tumor cell invasiveness and metastasis are the main causes of mortality in cancer. Tumor progression is composed of many steps, including primary tumor growth, local invasion, intravasation, survival in the circulation, pre-metastatic niche formation, and metastasis. All these steps are strictly controlled by microRNAs (miRNAs), small non-coding RNA that regulate gene expression at the post-transcriptional level. miRNAs can act as oncomiRs that promote tumor cell invasion and metastasis or as tumor suppressor miRNAs that inhibit tumor progression. These miRNAs regulate the actin cytoskeleton, the expression of extracellular matrix (ECM) receptors including integrins and ECM-remodeling enzymes comprising matrix metalloproteinases (MMPs), and regulate epithelial–mesenchymal transition (EMT), hence modulating cell migration and invasiveness. Moreover, miRNAs regulate angiogenesis, the formation of a pre-metastatic niche, and metastasis. Thus, miRNAs are biomarkers of metastases as well as promising targets of therapy. In this review, we comprehensively describe the role of various miRNAs in tumor cell migration, invasion, and metastasis.

Identifying Cancer-Relevant Mutations in the DLC START Domain Using Evolutionary and Structure-Function Analyses

Rho GTPase signaling promotes proliferation, invasion, and metastasis in a broad spectrum of cancers. Rho GTPase activity is regulated by the deleted in liver cancer (DLC) family of bona fide tumor suppressors which directly inactivate Rho GTPases by stimulating GTP hydrolysis. In addition to a RhoGAP domain, DLC proteins contain a StAR-related lipid transfer (START) domain. START domains in other organisms bind hydrophobic small molecules and can regulate interacting partners or co-occurring domains through a variety of mechanisms. In the case of DLC proteins, their START domain appears to contribute to tumor suppressive activity. However, the nature of this START-directed mechanism, as well as the identities of relevant functional residues, remain virtually unknown. Using the Catalogue of Somatic Mutations in Cancer (COSMIC) dataset and evolutionary and structure-function analyses, we identify several conserved residues likely to be required for START-directed regulation of DLC-1 and DLC-2 tumor-suppressive capabilities. This pan-cancer analysis shows that conserved residues of both START domains are highly overrepresented in cancer cells from a wide range tissues. Interestingly, in DLC-1 and DLC-2, three of these residues form multiple interactions at the tertiary structural level. Furthermore, mutation of any of these residues is predicted to disrupt interactions and thus destabilize the START domain. As such, these mutations would not have emerged from traditional hotspot scans of COSMIC. We propose that evolutionary and structure-function analyses are an underutilized strategy which could be used to unmask cancer-relevant mutations within COSMIC. Our data also suggest DLC-1 and DLC-2 as high-priority candidates for development of novel therapeutics that target their START domain.

Cullin 3/KCTD5 Promotes the Ubiqutination of Rho Guanine Nucleotide Dissociation Inhibitor 1 and Regulates Its Stability

Rho guanine nucleotide dissociation inhibitor 1 (RhoGDI1) plays important roles in numerous cellular processes, including cell motility, adhesion, and proliferation, by regulating the activity of Rho GTPases. Its expression is altered in various human cancers and is associated with malignant progression. Here, we show that RhoGDI1 interacts with Cullin 3 (CUL3), a scaffold protein for E3 ubiquitin ligase complexes. Ectopic expression of CUL3 increases the ubiquitination of RhoGDI1. Furthermore, potassium channel tetramerization domain containing 5 (KCTD5) also binds to RhoGDI1 and increases its interaction with CUL3. Ectopic expression of KCTD5 increases the ubiquitination of RhoGDI1, whereas its knockdown by RNA interference has the opposite effect. Depletion of KCTD5 or expression of dominant-negative CUL3 (DN-CUL3) enhances the stability of RhoGDI1. Our findings reveal a previously unknown mechanism for controlling RhoGDI1 degradation that involves a CUL3/KCTD5 ubiquitin ligase complex.

The Long Noncoding RNA LOC441461 (STX17-AS1) Modulates Colorectal Cancer Cell Growth and Motility

Simple Summary

Long noncoding RNA dysfunction is crucial for colorectal carcinoma (CRC) development. Whether the dysfunction of LOC441461, a novel lncRNA, can regulate cancer-related signaling pathways in cancer progression remains unclear. Here, we uncover the oncogenic role of LOC441461 in colon cancer cell growth and motility and identify a novel mechanism for LOC441461 knockdown-induced suppression of cancer motility through modulating Ras homolog family member A (RhoA)/Rho-associated protein kinase (ROCK) activity. This is the first report that LOC441461 knockdown impairs cell cycle progression and accelerates the apoptosis of colon cancer cells following chemotherapy drug treatment. The results suggest that LOC441461 expression confers drug sensitivity in colon cancer by inducing apoptosis. Our findings offer new insight into LOC441461 regulation and provide an application for colon cancer therapy in the future.

Abstract

Colorectal carcinoma (CRC) is one of the most prevalent cancers worldwide and has a high mortality rate. Long noncoding RNAs (lncRNAs) have been noted to play critical roles in cell growth; cell apoptosis; and metastasis in CRC. This study determined that LOC441461 expression was significantly higher in CRC tissues than in adjacent normal mucosa. Pathway enrichment analysis of LOC441461-coexpressed genes revealed that LOC441461 was involved in biological functions related to cancer cell growth and motility. Knockdown of the LOC441461 expression significantly suppressed colon cancer cell growth by impairing cell cycle progression and inducing cell apoptosis. Furthermore, significantly higher LOC441461 expression was discovered in primary colon tumors and metastatic liver tumors than in the corresponding normal mucosa, and LOC441461 knockdown was noted to suppress colon cancer cell motility. Knockdown of LOC441461 expression suppressed the phosphorylation of MLC and LIMK1 through the inhibition of RhoA/ROCK signaling. Overall, LOC441461 was discovered to play an oncogenic role in CRC cell growth and motility through RhoA/ROCK signaling. Our findings provide new insights into the regulation of lncRNAs and their application in the treatment of colon cancer

Identification of Survival-Associated Alternative Splicing Signatures in Lung Squamous Cell Carcinoma

Purpose: Alternative splicing (AS) is a post-transcriptional process that plays a significant role in enhancing the diversity of transcription and protein. Accumulating evidences have demonstrated that dysregulation of AS is associated with oncogenic processes. However, AS signature specifically in lung squamous cell carcinoma (LUSC) remains unknown. This study aimed to evaluate the prognostic values of AS events in LUSC patients.

Methods: The RNA-seq data, AS events data and corresponding clinical information were obtained from The Cancer Genome Atlas (TCGA) database. Univariate Cox regression analysis was performed to identify survival-related AS events and survival-related parent genes were subjected to Gene Ontology enrichment analysis and gene network analysis. The least absolute shrinkage and selection operator (LASSO) method and multivariate Cox regression analysis were used to construct prognostic prediction models, and their predictive values were assessed by Kaplan-Meier analysis and receiver operating characteristic (ROC) curves. Then a nomogram was established to predict the survival of LUSC patients. And the interaction network of splicing factors (SFs) and survival-related AS events was constructed by Spearman correlation analysis and visualized by Cytoscape.

Results: Totally, 467 LUSC patients were included in this study and 1,991 survival-related AS events within 1,433 genes were identified. SMAD4, FOS, POLR2L, and RNPS1 were the hub genes in the gene interaction network. Eight prognostic prediction models (seven types of AS and all AS) were constructed and all exhibited high efficiency in distinguishing good or poor survival of LUSC patients. The final integrated prediction model including all types of AS events exhibited the best prognostic power with the maximum AUC values of 0.778, 0.816, 0.814 in 1, 3, 5 years ROC curves, respectively. Meanwhile, the nomogram performed well in predicting the 1-, 3-, and 5-year survival of LUSC patients. In addition, the SF-AS regulatory network uncovered a significant correlation between SFs and survival-related AS events.

Conclusion: This is the first comprehensive study to analyze the role of AS events in LUSC specifically, which improves our understanding of the prognostic value of survival-related AS events for LUSC. And these survival-related AS events might serve as novel prognostic biomarkers and drug therapeutic targets for LUSC.

Autophagy regulates exosome secretion in rat nucleus pulposus cells via the RhoC/ROCK2 pathway

Our present study investigated whether exosome secretion of nucleus pulposus cells (NPCs) is regulated by autophagy. Different autophagic states of NPCs were induced by rapamycin (Rap), bafilomycin A1 (Baf) and other agents, and it was found that exosomes were secreted in an autophagy-dependent manner. Activation or inhibition of autophagy increased or decreased, respectively, the amount of exosomes that were released into the extracellular space. In addition, in order to confirm that Rap-promoted release of exosomes was mediated by autophagy rather than other pathways, we used autophagy associated gene 5 (ATG5) small-interfering RNA (siRNA) to silence the expression of ATG5 gene, which is indispensable for autophagy. The results showed that siRNA against ATG5 (siATG5) induced an accumulation of intraluminal vesicles (ILVs) in NPCs and a concomitant decrease in the amount of exosomes isolated from supernatant. Ras homolog gene (Rho) and Rho-associated coiled-coil forming protein kinase (ROCK) family molecules are capable of cytoskeletal remodeling and affecting vesicle transport. Therefore, we carried out targeted interventions and evaluated the effects of the RhoC/ROCK2 pathway on the secretion of exosomes within autophagic environment. Knockdown of RhoC and ROCK2 with corresponding siRNA significantly inhibited the secretion of exosomes originating from ILVs in NPCs, even when NPCs were subsequently treated with Rap. Taken together, our findings suggest that autophagy positively regulates expression levels of RhoC and ROCK2, and that the RhoC/ROCK2 pathway exerts a key function on NPCs-derived exosome secretion.