The action of small GTPases Rab11 and Rab25 in vesicle trafficking during cell migration

Machine-Learning-Based Identification of Key Feature RNA-Signature Linked to Diagnosis of Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is the third prime cause of malignancy-related mortality worldwide. Early and accurate identification of HCC is crucial for good prognosis, efficacy of therapy, and survival rates of the patients. We aimed to develop a machine-learning model incorporating differentially expressed RNA signatures with laboratory parameters to construct an RNA signature-based diagnostic model for HCC.

Methods

We have used five classifiers (KNN, RF, SVM, LGBM, and DNNs) to predict the liver disease (HCC). The classifiers were trained on 187 samples and then tested on 80 samples. The model included 22 features (age, sex, smoking, cirrhosis, non-cirrhosis, albumin, ALT, AST bilirubin (total and direct), INR, AFP, HBV Ag, HCV Abs, RQmiR-1298, RQmiR-1262, RQmiR-106b-3p, RQmRNARAB11A, and RQSTAT1, RQmRNAATG12, RQLnc-WRAP53, RQLncRNA- RP11-513I15.6).

Results

LGBM achieved the highest accuracy of 98.75% in predicting HCC among all models surpassing Random Forest (96.25%), DNN (91.25%), SVC (88.75%), and KNN (87.50%).

Conclusion

Our machine-learning model incorporating the expression data of RAB11A/STAT1/ATG12/miR-1262/miR-1298/miR-106b-3p/lncRNA-RP11-513I15.6/lncRNA-WRAP53 signature and clinical data represents a potential novel diagnostic model for HCC.

TRP Channels in Cancer: Signaling Mechanisms and Translational Approaches

Ion channels play a crucial role in a wide range of biological processes, including cell cycle regulation and cancer progression. In particular, the transient receptor potential (TRP) family of channels has emerged as a promising therapeutic target due to its involvement in several stages of cancer development and dissemination. TRP channels are expressed in a large variety of cells and tissues, and by increasing cation intracellular concentration, they monitor mechanical, thermal, and chemical stimuli under physiological and pathological conditions. Some members of the TRP superfamily, namely vanilloid (TRPV), canonical (TRPC), melastatin (TRPM), and ankyrin (TRPA), have been investigated in different types of cancer, including breast, prostate, lung, and colorectal cancer. TRP channels are involved in processes such as cell proliferation, migration, invasion, angiogenesis, and drug resistance, all related to cancer progression. Some TRP channels have been mechanistically associated with the signaling of cancer pain. Understanding the cellular and molecular mechanisms by which TRP channels influence cancer provides new opportunities for the development of targeted therapeutic strategies. Selective inhibitors of TRP channels are under initial scrutiny in experimental animals as potential anti-cancer agents. In-depth knowledge of these channels and their regulatory mechanisms may lead to new therapeutic strategies for cancer treatment, providing new perspectives for the development of effective targeted therapies.

Identification and validation of Rab11a in Rat orofacial inflammatory pain model induced by CFA

Orofacial pain (OFP) is a clinically very common and the most troubling condition; however, there is few effective way to relieve OFP. Rab11a, a small molecule guanosine triphosphate enzyme, is one of the Rab member family playing a vital role in intracellular endocytosis and the pain process. Therefore, we investigated the hub genes of rat OFP model induced by Complete Freund's Adjuvant (CFA) via re-analyzing microarray data (GSE111160). We found that Rab11a acted as a key hub gene in the process of OFP. During the validation of Rab11a, the OFP model was established by peripheral injection of CFA, which decreased the head withdrawal threshold (HWT) and head withdrawal lantency (HWL). Rab11a was observed in NeuN of Sp5C instead of GFAP/IBA-1, and double-IF of Rab11a and Fos positive cells were increased on the 7th day after CFA modeling statistically. Rab11a protein expression in TG and Sp5C of CFA group was also significantly increased. Interestingly, injection of Rab11a-targeted short hairpin RNA (Rab11a-shRNA) into Sp5C could reverse the decrease in HWT and HWL and reduce the expression level of Rab11a. Electrophysiological recording further demonstrated that the activity of Sp5C neuron was improved in CFA group, while Rab11a-shRNA considerably decreased the enhancement of Sp5C neuronal activity. Finally, we detected the expression level of p-PI3K, p-AKT, and p-mTOR in Sp5C of rats after injecting the Rab11a-shRNA virus. To our surprise, CFA upregulated the phosphorylation of PI3K, AKT and mTOR in Sp5C, and Rab11a-shRNA downregulated these molecules' expression. Our data suggest that CFA activates the PI3K/AKT signaling pathway through up-regulating Rab11a expression, which can induce OFP hyperalgesia development furtherly. Targeting Rab11a may be a novel treatment strategy for OFP.

Endocytosis in cancer and cancer therapy

Endocytosis is a complex process whereby cell surface proteins, lipids and fluid from the extracellular environment are packaged, sorted and internalized into cells. Endocytosis is also a mechanism of drug internalization into cells. There are multiple routes of endocytosis that determine the fate of molecules, from degradation in the lysosomes to recycling back to the plasma membrane. The overall rates of endocytosis and temporal regulation of molecules transiting through endocytic pathways are also intricately linked with signalling outcomes. This process relies on an array of factors, such as intrinsic amino acid motifs and post-translational modifications. Endocytosis is frequently disrupted in cancer. These disruptions lead to inappropriate retention of receptor tyrosine kinases on the tumour cell membrane, changes in the recycling of oncogenic molecules, defective signalling feedback loops and loss of cell polarity. In the past decade, endocytosis has emerged as a pivotal regulator of nutrient scavenging, response to and regulation of immune surveillance and tumour immune evasion, tumour metastasis and therapeutic drug delivery. This Review summarizes and integrates these advances into the understanding of endocytosis in cancer. The potential to regulate these pathways in the clinic to improve cancer therapy is also discussed.

Kazrin promotes dynein/dynactin-dependent traffic from early to recycling endosomes

Kazrin is a protein widely expressed in vertebrates whose depletion causes a myriad of developmental defects, in part derived from altered cell adhesion and migration, as well as failure to undergo epidermal to mesenchymal transition. However, the primary molecular role of kazrin, which might contribute to all these functions, has not been elucidated yet. We previously identified one of its isoforms, kazrin C, as a protein that potently inhibits clathrin-mediated endocytosis when overexpressed. We now generated kazrin knock-out mouse embryonic fibroblasts to investigate its endocytic function. We found that kazrin depletion delays juxtanuclear enrichment of internalized material, indicating a role in endocytic traffic from early to recycling endosomes. Consistently, we found that the C-terminal domain of kazrin C, predicted to be an intrinsically disordered region, directly interacts with several early endosome (EE) components, and that kazrin depletion impairs retrograde motility of these organelles. Further, we noticed that the N-terminus of kazrin C shares homology with dynein/dynactin adaptors and that it directly interacts with the dynactin complex and the dynein light intermediate chain 1. Altogether, the data indicate that one of the primary kazrin functions is to facilitate endocytic recycling by promoting dynein/dynactin-dependent transport of EEs or EE-derived transport intermediates to the recycling endosomes.

Rab11a promotes the malignant progression of ovarian cancer by inducing autophagy

BACKGROUND

Rab11a is a novel identified tumorigenic factor involved in different cancers.

OBJECTIVE

This study aimed to assess the biological function of Rab11a in ovarian cancer (OC).

METHODS

GEPIA database and real-time PCR were used to determine Rab11a expression in OC tissues and normal ovarian tissues. CCK-8, cell cycle, wound healing, transwell, and enzyme linked immunosorbent assay were used to detect the effects of Rab11a knockdown or overexpression on the proliferation, migration, and invasion of OC cells. Western blot analysis of autophagy-related markers and immunofluorescence staining of LC3 were performed to determine autophagy induction in Rab11a-silenced or overexpressed OC cells. Moreover, autophagy inhibitor 3-MA was employed to clarify the effects of Rab11a-regulated autophagy on the malignant phenotypes of OC cells.

RESULTS

The mRNA level of Rab11a was increased in tumor tissues from OC patients as compared to the normal ovarian tissues. Knockdown of Rab11a in OVCAR-3 cells inhibited the growth of OC cells and led to cell cycle arrest, accompanied by reduced expression of PCNA and Cyclin D1. Rab11a deficiency suppressed migration and invasion of OC cells, accompanied by decreased secretion of MMP-2 and MMP-9. Silence of Rab11a impeded autophagy induction, as evidenced by decreased LC3 puncta formation, reduced abundance of LC3II and Beclin1, and increased p62 protein expression. In contrast, the ectopic expression of Rab11a in A2780 cells exerted opposite effects. Interestingly, autophagy inhibitor 3-MA abolished the effects of Rab11a overexpression on autophagy, proliferation, migration, and invasion.

CONCLUSIONS

Rab11a promotes the malignant phenotypes of OC cells by inducing autophagy.

Fluorescence Imaging of Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor Resistance in Non-Small Cell Lung Cancer

Simple Summary

Lung cancer is the leading cause of cancer-related deaths, with a low (<21%) 5-year survival rate. Lung cancer is often driven by the misfunction of molecules on the surface of cells of the epithelium, which orchestrate mechanisms by which these cells grow and proliferate. Beyond common non-specific treatments, such as chemotherapy or radiotherapy, among molecular-specific treatments, a number of small-molecule drugs that block cancer-driven molecular activity have been developed. These drugs initially have significant success in a subset of patients, but these patients systematically develop resistance within approximately one year of therapy. Substantial efforts towards understanding the mechanisms of resistance have focused on the genomics of cancer progression, the response of cells to the drugs, and the cellular changes that allow resistance to develop. Fluorescence microscopy of many flavours has significantly contributed to the last two areas, and is the subject of this review.

Abstract

Non-small cell lung cancer (NSCLC) is a complex disease often driven by activating mutations or amplification of the epidermal growth factor receptor (EGFR) gene, which expresses a transmembrane receptor tyrosine kinase. Targeted anti-EGFR treatments include small-molecule tyrosine kinase inhibitors (TKIs), among which gefitinib and erlotinib are the best studied, and their function more often imaged. TKIs block EGFR activation, inducing apoptosis in cancer cells addicted to EGFR signals. It is not understood why TKIs do not work in tumours driven by EGFR overexpression but do so in tumours bearing classical activating EGFR mutations, although the latter develop resistance in about one year. Fluorescence imaging played a crucial part in research efforts to understand pro-survival mechanisms, including the dysregulation of autophagy and endocytosis, by which cells overcome the intendedly lethal TKI-induced EGFR signalling block. At their core, pro-survival mechanisms are facilitated by TKI-induced changes in the function and conformation of EGFR and its interactors. This review brings together some of the main advances from fluorescence imaging in investigating TKI function and places them in the broader context of the TKI resistance field, highlighting some paradoxes and suggesting some areas where super-resolution and other emerging methods could make a further contribution.

Zebrafish intestinal transcriptome highlights subdued inflammatory responses to dietary soya bean and efficacy of yeast β-glucan

Anti-nutritional factors in dietary components can have a negative impact on the intestinal barrier. Here, we present soya bean-induced changes in the intestine of juvenile zebrafish and the effect of yeast β-glucan through a transcriptomic approach. The inclusion of soya bean meal affected the expression of several intestinal barrier function-related genes like arl4ca, rab25b, rhoub, muc5ac, muc5d, clcn2c and cltb in zebrafish. Several metabolic genes like cyp2x10.2, cyp2aa2, aldh3a2b, crata, elovl4, elovl6, slc51a, gpat2 and ATP-dependent peptidase activity (lonrf, clpxb) were altered in the intestinal tissue. The expression of immune-related genes like nlrc3, nlrp12, gimap8, prdm1 and tph1a, and genes related to cell cycle, DNA damage and DNA repair (e.g. spo11, rad21l1, nabp1b, spata22, tdrd9) were also affected in the soya bean fed group. Furthermore, our study suggests the plausible effect of yeast β-glucan through the modulation of several genes that regulate immune responses and barrier integrity. Our findings indicate a subdued inflammation in juvenile zebrafish fed soya bean meal and the efficacy of β-glucan to counter these subtle inflammatory responses.

RAB11-Mediated Trafficking and Human Cancers: An Updated Review

Simple Summary

The small GTPase RAB11 is a master regulator of both vesicular trafficking and membrane dynamic defining the surface proteome of cellular membranes. As a consequence, the alteration of RAB11 activity induces changes in both the sensory and the transduction apparatuses of cancer cells leading to tumor progression and invasion. Here, we show that this strictly depends on RAB11′s ability to control the sorting of signaling receptors from endosomes. Therefore, RAB11 is a potential therapeutic target over which to develop future therapies aimed at dampening the acquisition of aggressive traits by cancer cells.

Abstract

Many disorders block and subvert basic cellular processes in order to boost their progression. One protein family that is prone to be altered in human cancers is the small GTPase RAB11 family, the master regulator of vesicular trafficking. RAB11 isoforms function as membrane organizers connecting the transport of cargoes towards the plasma membrane with the assembly of autophagic precursors and the generation of cellular protrusions. These processes dramatically impact normal cell physiology and their alteration significantly affects the survival, progression and metastatization as well as the accumulation of toxic materials of cancer cells. In this review, we discuss biological mechanisms ensuring cargo recognition and sorting through a RAB11-dependent pathway, a prerequisite to understand the effect of RAB11 alterations in human cancers.

Rab11a Is Overexpressed in Gastric Cancer and Regulates FAK/AKT Signaling

Dysregulation of Rab11a has been implicated in the progression of several cancers. However, there have been no such studies for human gastric cancers. In the current study, we examined Rab11a protein expression and found it was upregulated in 49 of 108 gastric cancer tissues and correlated with local invasion, nodal metastasis, and advanced stage. Rab11a protein was higher in gastric cancer cell lines than normal gastric cell line. We transfected Rab11a plasmid and siRNA in both MGC803 and AGS cell lines. Rab11a overexpression increased the cell growth rate, colony numbers, and invasion ability in both MGC803 and AGS cell lines. Downregulation of Rab11a using siRNA decreased the cell proliferation rate, colony numbers, and inhibited invasion. Rab11a overexpression also conferred cisplatin resistance. Annexin V/PI staining showed that Rab11a overexpression suppressed cisplatin-induced apoptosis, while Rab11a depletion promoted cell apoptosis. We also showed that Rab11a overexpression maintained mitochondrial membrane potential. Western blot analysis revealed that Rab11a increased protein expression of MMP2, cyclin D1, Bcl-2, p-FAK, and p-AKT, while Rab11a depletion showed the opposite effects. Blockage of FAK using inhibitor downregulated Bcl-2, cyclin D1, MMP2, and p-AKT expression and abolished the effects of Rab11a on these proteins. In summary, our data demonstrated that Rab11a is upregulated in human gastric cancers. Rab11a facilitated cell proliferation and invasion, as well as cisplatin sensitivity and mitochondrial membrane potential, possibly via the FAK/AKT signaling pathway.

Rab11a regulates MMP2 expression by activating the PI3K/AKT pathway in human hepatocellular carcinoma cells

As a member of the Rab GTPase family, Rab11a plays an important role in vesicle transport and tumor progression. However, it is not clear whether it can also be used as an oncoprotein in hepatocellular carcinoma (HCC). In this study, database and immunohistochemical analyses showed that Rab11a was highly expressed in HCC tissues, and associated with poor clinical prognosis. Rab11a overexpression promoted the proliferation, migration, invasion, and anti-apoptosis of human HCC cell lines, MHCC-97H and HCC-LM3, whereas the downregulation of Rab11a inhibited these biological tumor activities. Nude mice xenograft demonstrated that Rab11a had a positive effect on the growth of hepatocellular carcinoma cells in vivo. Further studies found that the PI3K/AKT pathway and matrix metalloproteinase 2 (MMP2) upregulation can be activated by over-expression of Rab11a. However, MMP2 upregulation induced by Rab11a can be inhibited by the PI3K/AKT pathway inhibitor, LY294002. Altogether, our study established for the first time that Rab11a can play a pro-cancer role in HCC, as a novel oncoprotein, by activating the PI3K/AKT pathway to regulate MMP2 expression.

Rab11A regulates dense granule transport and secretion during Toxoplasma gondii invasion of host cells and parasite replication

Toxoplasma gondii possesses an armada of secreted virulent factors that enable parasite invasion and survival into host cells. These factors are contained in specific secretory organelles, the rhoptries, micronemes and dense granules that release their content upon host cell recognition. Dense granules are secreted in a constitutive manner during parasite replication and play a crucial role in modulating host metabolic and immune responses. While the molecular mechanisms triggering rhoptry and microneme release upon host cell adhesion have been well studied, constitutive secretion remains a poorly explored aspect of T. gondii vesicular trafficking. Here, we investigated the role of the small GTPase Rab11A, a known regulator of exocytosis in eukaryotic cells. Our data revealed an essential role of Rab11A in promoting the cytoskeleton driven transport of dense granules and the release of their content into the vacuolar space. Rab11A also regulates transmembrane protein trafficking and localization during parasite replication, indicating a broader role of Rab11A in cargo exocytosis at the plasma membrane. Moreover, we found that Rab11A also regulates extracellular parasite motility and adhesion to host cells. In line with these findings, MIC2 secretion was altered in Rab11A-defective parasites, which also exhibited severe morphological defects. Strikingly, by live imaging we observed a polarized accumulation of Rab11A-positive vesicles and dense granules at the apical pole of extracellular motile and invading parasites suggesting that apically polarized Rab11A-dependent delivery of cargo regulates early secretory events during parasite entry into host cells.

Toxoplasma gondii (T. gondii) is a highly prevalent parasite infecting a wide range of animals as well as humans. T. gondii secretes numerous virulent factors contained in specific organelles, termed the rhoptries, micronemes and dense granules. These factors are released upon host cell recognition and enable parasite invasion and subsequent development into an intracellular vacuole. In particular, dense granules contain critical effectors that modulate intrinsic defenses of infected host cells ensuring parasite survival and dissemination. The mechanisms regulating dense granule secretion have not been elucidated. In this study, we unraveled a novel role for the T. gondii GTPase Rab11A in promoting dense granule transport along the parasite cytoskeleton and their content release into the vacuolar space during parasite replication. We also found that T. gondii Rab11A regulates extracellular parasite motility and adhesion to host cells suggesting a broader role in distinct secretory pathways essential for parasite virulence.

Rab5 regulates the proliferation, migration and invasion of glioma cells via cyclin E

Glioma is the most common and lethal type of primary brain tumor, with a high mortality and recurrence rate. Rab5, which serves as a classic ontogenetic gene, is highly expressed in various types of tumor, including lung cancer, hepatocellular carcinoma and ovarian cancer. However, the exact role and the underlying mechanism of Rab5 in glioma remain unknown. Herein, the role of Rab5 in the tumorigenesis and metastasis of glioma cells was investigated. The upregulation of Rab5 in glioma tissues and cells was observed. The expression of Rab5 was positively associated with proliferation, migration and invasion of glioma cells. Moreover, Rab5 was involved in the cell cycle of glioma cells via the regulation of cyclin E. Data presented in the present study suggest Rab5 as a potential novel diagnostic and prognosis marker of glioma.

Knockdown Rab11-FIP2 inhibits migration and invasion of nasopharyngeal carcinoma via suppressing Rho GTPase signaling

Rab11 family interacting protein 2 (Rab11-FIP2) is a conserved protein and effector molecule for the small GTPase Rab11. By interacting with Rab11 and MYO5B, Rab11-FIP2 regulates endosome trafficking of plasma membrane proteins, promoting cellular motility. The endosomal trafficking system in nasopharyngeal carcinoma (NPC) remains unclear. Here, an outlier analysis using the Oncomine database suggested that Rab11-FIP2 but not Rab11 and MYO5B was overexpressed in NPC. We confirmed that the transcription of Rab11-FIP2 was upregulated in NPC cell lines and primary tumor tissues as compared with a normal nasopharyngeal epithelial cell line and normal nasopharynx tissues. We further confirmed the elevated protein expression level of Rab11-FIP2 in NPC biopsies. Instead of regulating the epithelial-mesenchymal transition or Akt signaling pathway, knockdown of Rab11-FIP2 inhibited the migration and invasion ability of NPC cell lines by decreasing the expression of Rac and Cdc42. In summary, Rab11-FIP2 could be an oncogene in NPC, mainly contributing to metastatic capacity by activating Rho GTPase signaling.

Dual gene deficient models of ApcMin/+ mouse in assessing molecular mechanisms of intestinal carcinogenesis

The Apc^Min/+ mouse, carrying an inactivated allele of the adenomatous polyposis coli (Apc) gene, is a widely used animal model of human colorectal tumorigenesis. While crossed with other gene knockout or knock-in mice, these mice possess advantages in investigation of human intestinal tumorigenesis. Intestinal tumor pathogenesis involves multiple gene alterations; thus, various double gene deficiency models could provide novel insights into molecular mechanisms of tumor biology, as well as gene-gene interactions involved in intestinal tumor development and assessment of novel strategies for preventing and treating intestinal cancer. This review discusses approximately 100 double gene deficient mice and their associated intestinal tumor development and progression phenotypes. The dual gene knockouts based on the Apc mutation background consist of inflammation and immune-related, cell cycle-related, Wnt/β-catenin signaling-related, tumor growth factor (TGF)-signaling-related, drug metabolism-related, and transcription factor genes, as well as some oncogenes and tumor suppressors. Future studies should focus on conditional or inducible dual or multiple mouse gene knockout models to investigate the molecular mechanisms underlying intestinal tumor development, as well as potential drug targets.

Rab11a promotes proliferation and invasion through regulation of YAP in non-small cell lung cancer

Rab11a, an evolutionarily conserved Rab GTPases, plays important roles in intracellular transport and has been implicated in cancer progression. However, its role in human non-small cell lung cancer (NSCLC) has not been explored yet. In this study, we discovered that Rab11a protein was upregulated in 57/122 NSCLC tissues. Rab11a overexpression associated with advanced TNM stage, positive nodal status and poor patient prognosis. Rab11a overexpression promoted proliferation, colony formation, invasion and migration with upregulation of cyclin D1, cyclin E, and downregulation of p27 in NSCLC cell lines. Nude mice xenograft demonstrated that Rab11a promoted in vivo cancer growth. Importantly, we found that Rab11a induced YAP protein and inhibited Hippo signaling. Depletion of YAP abolished the effects of Rab11a on cell cycle proteins and cell proliferation. Furthermore, immunoprecipitation showed that Rab11a interacted with YAP in lung cancer cells. In conclusion, the present study suggestes that Rab11a serves as an important oncoprotein and a regulator of YAP in NSCLC.

Identification of Genes Enriched in GnRH Neurons by Translating Ribosome Affinity Purification and RNAseq in Mice

Gonadotropin-releasing hormone (GnRH) neurons are a nexus of fertility regulation. We used translating ribosome affinity purification coupled with RNA sequencing to examine messenger RNAs of GnRH neurons in adult intact and gonadectomized (GDX) male and female mice. GnRH neuron ribosomes were tagged with green fluorescent protein (GFP) and GFP-labeled polysomes isolated by immunoprecipitation, producing one RNA fraction enhanced for GnRH neuron transcripts and one RNA fraction depleted. Complementary DNA libraries were created from each fraction and 50-base, paired-end sequencing done and differential expression (enhanced fraction/depleted fraction) determined with a threshold of >1.5- or <0.66-fold (false discovery rate P ≤ 0.05). A core of ∼840 genes was differentially expressed in GnRH neurons in all treatments, including enrichment for Gnrh1 (∼40-fold), and genes critical for GnRH neuron and/or gonadotrope development. In contrast, non-neuronal transcripts were not enriched or were de-enriched. Several epithelial markers were also enriched, consistent with the olfactory epithelial origins of GnRH neurons. Interestingly, many synaptic transmission pathways were de-enriched, in accordance with relatively low innervation of GnRH neurons. The most striking difference between intact and GDX mice of both sexes was a marked downregulation of genes associated with oxidative phosphorylation and upregulation of glucose transporters in GnRH neurons from GDX mice. This may suggest that GnRH neurons switch to an alternate fuel to increase adenosine triphosphate production in the absence of negative feedback when GnRH release is elevated. Knowledge of the GnRH neuron translatome and its regulation can guide functional studies and can be extended to disease states, such as polycystic ovary syndrome.

Rab25 acts as an oncogene in luminal B breast cancer and is causally associated with Snail driven EMT

The Rab GTPases regulate vesicular trafficking machinery that transports and delivers a diverse pool of cargo, including growth factor receptors, integrins, nutrient receptors and junction proteins to specific intracellular sites. The trafficking machinery is indeed a major posttranslational modifier and is critical for cellular homeostasis. Deregulation of this stringently controlled system leads to a wide spectrum of disorders including cancer. Herein we demonstrate that Rab25, a key GTPase, mostly decorating the apical recycling endosome, is a dichotomous variable in breast cancer cell lines with higher mRNA and protein expression in Estrogen Receptor positive (ER+ve) lines. Rab25 and its effector, Rab Coupling Protein (RCP) are frequently coamplified and coordinately elevated in ER+ve breast cancers. In contrast, Rab25 levels are decreased in basal-like and almost completely lost in claudin-low tumors. This dichotomy exists despite the presence of the 1q amplicon that hosts Rab25 across breast cancer subtypes and is likely due to differential methylation of the Rab25 promoter. Functionally, elevated levels of Rab25 drive major hallmarks of cancer including indefinite growth and metastasis but in case of luminal B breast cancer only. Importantly, in such ER+ve tumors, coexpression of Rab25 and its effector, RCP is significantly associated with a markedly worsened clinical outcome. Importantly, in claudin-low cell lines, exogenous Rab25 markedly inhibits cell migration. Similarly, during Snail-induced epithelial to mesenchymal transition (EMT) exogenous Rab25 potently reverses Snail-driven invasion. Overall, this study substantiates a striking context dependent role of Rab25 in breast cancer where Rab25 is amplified and enhances aggressiveness in luminal B cancers while in claudin-low tumors, Rab25 is lost indicating possible anti-tumor functions.

EVI5 is a novel independent prognostic predictor in hepatocellular carcinoma after radical hepatectomy

The present study explored the correlation of ecotropic viral integration site 5 (EVI5) expression with clinicopathological features and prognosis in hepatocellular carcinoma (HCC). A total of 205 HCC patients were included retrospectively. Quantitative real-time polymerase chain reaction (RT-qPCR) and western blotting were performed to detect the profile of EVI5 expression in HCC cell lines and fresh tissues. Archived paraffin-embedded specimens were investigated for EVI5 expression by immunohistochemistry (IHC). Both the mRNA and protein levels of EVI5 were obviously upregulated in HCC cell lines and tumor tissues. EVI5 protein level was closely associated with the clinicopathological characteristics, including liver function (P=0.013), venous invasion (P=0.015) and TNM stage (P=0.014). Furthermore, univariate analysis showed that the patients with high EVI5 expression indicated shorter overall survival (OS, P<0.001) and recurrence-free survival (RFS, P=0.001) than those with low EVI5 expression. Importantly, high EVI5 expression also exerts predictive power for higher postoperative recurrence rate by stratified analysis. Multivariate Cox regression analysis demonstrated that OS was correlated with both tumor number (P=0.046) and EVI5 expression (P<0.001) and that RFS was correlated with serum AFP (P=0.023), tumor number (P=0.036) and EVI5 expression (P<0.001). Taken together, EVI5 is an useful independent prognostic marker of survival and recurrence in hepatocellular carcinoma.

High expression of Rab25 contributes to malignant phenotypes and biochemical recurrence in patients with prostate cancer after radical prostatectomy

Background

Ras-related protein 25 (Rab25) functions either as an oncogene or a tumor suppressor with a cancer type-dependent manner. We aimed to investigate clinical significance of Rab25 in prostate cancer (PCa).

Methods

Quantitative real-time polymerase chain reaction, Western blot and immunohistochemistry were respectively performed to detect Rab25 mRNA and protein expression in PCa and adjacent non-cancerous prostate tissues. Receiver-operating characteristic curve analysis was used to evaluate predictive diagnostic value of Rab25. Associations of Rab25 expression with various clinicopathological characteristics and biochemical recurrence-free survival of PCa patients were statistically evaluated. In vitro, PCa cell proliferation was assessed by CCK-8 assay, and the cell migration and invasion activities were evaluated by Transwell assay, following the transfection of Rab25 small interfering RNA.

Results

Ras-related protein 25 mRNA and protein expression in PCa tissues were both significantly higher than adjacent non-cancerous prostate tissues (both P < 0.001). The area under the curve of Rab25 immunoreactive score (IRS) was 0.896 (P < 0.001) with 74.0% sensitivity and 95.0% specificity. High Rab25 IRS was significantly associated with high Gleason score (P = 0.02) and distant metastasis (P = 0.01). PCa patients with high Rab25 IRS had shorter overall and biochemical recurrence-free survivals than those with low Rab25 IRS (both P < 0.001). Cox regression analysis identified Rab25 as an independent biomarker for both overall and biochemical recurrence-free survivals of PCa patients. By exploring its activities in vitro, Rab25 downregulation was found to inhibit PCa cell proliferation, migration and invasion.

Conclusions

High expression of Rab25 may contribute to malignant progression and biochemical recurrence of PCa patients after radical prostatectomy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-017-0411-0) contains supplementary material, which is available to authorized users.

Rho GTPases operating at the Golgi complex: Implications for membrane traffic and cancer biology

The Golgi complex is the central unit of the secretory pathway, modifying, processing and sorting proteins and lipids to their correct cellular localisation. Changes to proteins at the Golgi complex can have deleterious effects on the function of this organelle, impeding trafficking routes through it, potentially resulting in disease. It is emerging that several Rho GTPase proteins, namely Cdc42, RhoBTB3, RhoA and RhoD are at least in part localised to the Golgi complex, and a number of studies have shown that dysregulation of their levels or activity can be associated with cellular changes which ultimately drive cancer progression. In this mini-review we highlight some of the recent work that explores links between form and function of the Golgi complex, Rho GTPases and cancer.

Rab11a sustains GSK3β/Wnt/β-catenin signaling to enhance cancer progression in pancreatic cancer

The Rab family GTPases regulate many major biological processes during tumor progression such as cell proliferation, cytoskeleton organization, cell movement, and invasion. The present study aims to examine the clinical significance, biological roles, and molecular mechanism of Rab11a in pancreatic cancer progression. We examined expression pattern of Rab11a in 96 cases of pancreatic cancer specimens using immunohistochemistry and found Rab11a overexpression correlated with tumor-node-metastasis (TNM) stage (p = 0.0111). We depleted Rab11a in Bxpc3 cells using small interfering RNA (siRNA) and overexpressed Rab11a in Capan2 cells. Knockdown of Rab11a inhibited cell growth, invasion, and cell cycle progression while its overexpression facilitated cell growth, invasion, and cell cycle progression. In addition, Rab11a overexpression increased gemcitabine resistance and inhibited gemcitabine-induced apoptosis in Capan2 cells while its depletion reduced drug resistance. We investigated the role of Rab11a in the regulation of Wnt/β-catenin signaling and we demonstrated that Rab11a overexpression upregulated GSK3β phosphorylation and nuclear β-catenin accumulation. Rab11a depletion inhibited while its overexpression enhanced β-catenin/T-cell factor (TCF) transcriptional activity with corresponding change of Wnt target genes including cyclin D1, cyclin E, MMP7, and c-myc. Wnt inhibitor (FH535) partly attenuated the effects of Rab11a on cell proliferation and Wnt target genes. In conclusion, the present study demonstrated that Rab11a promotes aggressiveness of pancreatic cancer through GSK3β/Wnt/β-catenin signaling pathway.

Rab7b at the intersection of intracellular trafficking and cell migration

Rab proteins are small GTPases essential for controlling and coordinating intracellular traffic. The small GTPase Rab7b regulates the retrograde transport from late endosomes toward the Trans-Golgi Network (TGN), and is important for the proper trafficking of several receptors such as Toll-like receptors (TLRs) and sorting receptors. We recently identified the actin motor protein myosin II as a new interaction partner for Rab7b, and found that Rab7b transport is dependent on myosin II. Interestingly, we also discovered that Rab7b influences the phosphorylation state of myosin II by controlling the activation status of the small GTPase RhoA. Consequently, Rab7b is important for the remodeling of actin filaments in processes such as stress fiber formation, cell adhesion, polarization and cell migration. Our finding that Rab7b can control actomyosin reorganization reveals yet another important role for Rab proteins, in addition to their already established role as master regulators of intracellular transport. Here we discuss our findings and speculate how they can explain the importance of Rab7b in dendritic cells (DCs).

The role of endocytic Rab GTPases in regulation of growth factor signaling and the migration and invasion of tumor cells

Metastasis is characterized pathologically by uncontrolled cell invasion, proliferation, migration and angiogenesis. It is a multistep process that encompasses the modulation of membrane permeability and invasion, cell spreading, cell migration and proliferation of the extracellular matrix, increase in cell adhesion molecules and interaction, decrease in cell attachment and induced survival signals and propagation of nutrient supplies (blood vessels). In cancer, a solid tumor cannot expand and spread without a series of synchronized events. Changes in cell adhesion receptor molecules (e.g., integrins, cadherin-catenins) and protease expressions have been linked to tumor invasion and metastasis. It has also been determined that ligand-growth factor receptor interactions have been associated with cancer development and metastasis via the endocytic pathway. Specifically, growth factors, which include IGF-1 and IGF-2 therapy, have been associated with most if not all of the features of metastasis. In this review, we will revisit some of the key findings on perhaps one of the most important hallmarks of cancer metastasis: cell migration and cell invasion and the role of the endocytic pathway in mediating this phenomenon.

EGFR endocytosis is a novel therapeutic target in lung cancer with wild-type EGFR

Oncogenic alterations of epidermal growth factor receptor (EGFR) signaling are frequently observed in lung cancer patients with worse differentiation and poor prognosis. However, the therapeutic efficacy of EGFR-tyrosine kinase inhibitors (TKIs) is currently limited in selected patients with EGFR mutations. Therefore, in this study, we investigated the potential molecular mechanism that contributes to cell viability and the response of gefitinib, one of the EGFR-TKIs, in lung cancer models with wide-type EGFR (wtEGFR). Interestingly, we found that EGF-induced EGFR endocytosis is existed differently between gefitinib-sensitive and -insensitive lung cancer cell lines. Suppressing EGFR endocytos decreased cell viability and increased apoptotic cell death in gefitinib-insensitive lung cancer with wtEGFR in vitro and in vivo. In addition, we found that Rab25 was differentially expressed in between gefitinib-sensitive and -insensitive lung cancer cells. Rab25 knockdown caused the changed EGFR endocytosis and reverted the gefitinib response in gefitinib-sensitive lung cancer with wtEGFR in vitro and in vivo. Taken together, our findings suggest a novel insight that EGFR endocytosis is a rational therapeutic target in lung cancer with wtEGFR, in which the combined efficacy with gefitinib is expected. Furthermore, we demonstrated that Rab25 plays an important role in EGFR endocytosis and gefitinib therapy.

Exploration of panviral proteome: high-throughput cloning and functional implications in virus-host interactions

Throughout the long history of virus-host co-evolution, viruses have developed delicate strategies to facilitate their invasion and replication of their genome, while silencing the host immune responses through various mechanisms. The systematic characterization of viral protein-host interactions would yield invaluable information in the understanding of viral invasion/evasion, diagnosis and therapeutic treatment of a viral infection, and mechanisms of host biology. With more than 2,000 viral genomes sequenced, only a small percent of them are well investigated. The access of these viral open reading frames (ORFs) in a flexible cloning format would greatly facilitate both in vitro and in vivo virus-host interaction studies. However, the overall progress of viral ORF cloning has been slow. To facilitate viral studies, we are releasing the initiation of our panviral proteome collection of 2,035 ORF clones from 830 viral genes in the Gateway® recombinational cloning system. Here, we demonstrate several uses of our viral collection including highly efficient production of viral proteins using human cell-free expression system in vitro, global identification of host targets for rubella virus using Nucleic Acid Programmable Protein Arrays (NAPPA) containing 10,000 unique human proteins, and detection of host serological responses using micro-fluidic multiplexed immunoassays. The studies presented here begin to elucidate host-viral protein interactions with our systemic utilization of viral ORFs, high-throughput cloning, and proteomic technologies. These valuable plasmid resources will be available to the research community to enable continued viral functional studies.

Ion channels in cancer: future perspectives and clinical potential

Ion transport across the cell membrane mediated by channels and carriers participate in the regulation of tumour cell survival, death and motility. Moreover, the altered regulation of channels and carriers is part of neoplastic transformation. Experimental modification of channel and transporter activity impacts tumour cell survival, proliferation, malignant progression, invasive behaviour or therapy resistance of tumour cells. A wide variety of distinct Ca(2+) permeable channels, K(+) channels, Na(+) channels and anion channels have been implicated in tumour growth and metastasis. Further experimental information is, however, needed to define the specific role of individual channel isoforms critically important for malignancy. Compelling experimental evidence supports the assumption that the pharmacological inhibition of ion channels or their regulators may be attractive targets to counteract tumour growth, prevent metastasis and overcome therapy resistance of tumour cells. This short review discusses the role of Ca(2+) permeable channels, K(+) channels, Na(+) channels and anion channels in tumour growth and metastasis and the therapeutic potential of respective inhibitors.

Epithelial splicing regulator protein 1 and alternative splicing in somatotroph adenomas

Somatotroph adenomas secrete supraphysiological amounts of GH, causing acromegaly. We have previously hypothesized that epithelial mesenchymal transition (EMT) may play a central role in the progression of these adenomas and that epithelial splicing regulator 1 (ESRP1) may function prominently as a master regulator of the EMT process in pituitary adenomas causing acromegaly. To further elucidate the role of ESRP1 in somatotroph adenomas and in EMT progression, we used RNA sequencing (RNAseq) to sequence somatotroph adenomas characterized by high and low ESRP1 levels. Transcripts identified by RNAseq were analyzed in 65 somatotroph adenomas and in GH-producing pituitary rat cells with a specific knockdown of Esrp1. The clinical importance of the transcripts was further investigated by correlating mRNA expression levels with clinical indices of disease activity and treatment response. Many of the transcripts and isoforms identified by RNAseq and verified by quantitative PCR were involved in vesicle transport and calcium signaling and were associated with clinical outcomes. Silencing Esrp1 in GH3 cells resulted in changes of gene expression overlapping the data observed in human somatotroph adenomas and revealed a decreased granulation pattern and attenuated GH release. We observed an alternative splicing pattern for F-box and leucine-rich repeat protein 20, depending on the ESPR1 levels and on changes in circulating IGF-I levels after somatostatin analog treatment. Our study indicates that ESRP1 in somatotroph adenomas regulates transcripts that may be essential in the EMT progression and in the response to somatostatin analog treatment.

The Evi5 family in cellular physiology and pathology

The Ecotropic viral integration site 5 (Evi5) and Evi5-like (Evi5L) belong to a small subfamily of the Tre-2/Bub2/Cdc16 (TBC) domain-containing proteins with enigmatically divergent roles as modulators of cell cycle progression, cytokinesis, and cellular membrane traffic. First recognized as a potential oncogene and a cell cycle regulator, Evi5 acts as a GTPase Activating Protein (GAP) for Rab11 in cytokinesis. On the other hand, its homologue Evi5L has Rab-GAP activity towards Rab10 as well as Rab23, and has been implicated in primary cilia formation. Recent genetic susceptibility analysis points to Evi5 as an important factor in susceptibility to multiple sclerosis. We discuss below the myriad of cellular functions exhibited by the Evi5 family members, and their associations with disease conditions.

Rab25 in cancer: a brief update

Derailed endocytosis is a hallmark of cancer. The endocytic pathway, as demonstrated by our laboratory, is a frequent target of genomic aberrations in cancer and plays a critical role in the maintenance of cellular polarity, stem cell function, bioenergetics, proliferation, motility, invasion, metastasis, apoptosis and autophagy. The Rab GTPases, along with their effectors, are critical regulators of this endocytic machinery and can have a huge impact on the cellular itinerary of growth and metabolism. Rab25 is an epithelial-cell-specific member of the Rab GTPase superfamily, sharing close homology with Rab11a, the endosomal recycling Rab GTPase. RAB25 has been implicated in various cancers, with reports presenting it as both an oncogene and a tumour-suppressor gene. At the cellular level, Rab25 was shown to contribute to invasiveness of cancer cells by regulating integrin trafficking. Recently, our laboratory uncovered a critical role for Rab25 in cellular energetics. Assimilating all of the existing evidence, in the present review, we give an updated overview of the complex and often context-dependent role of Rab25 in cancer.

Rab GTPases are required for early orientation of the left-right axis in Xenopus

The earliest steps of left-right (LR) patterning in Xenopus embryos are driven by biased intracellular transport that ensures a consistently asymmetric localization of maternal ion channels and pumps in the first 2-4 blastomeres. The subsequent differential net efflux of ions by these transporters generates a bioelectrical asymmetry; this LR voltage gradient redistributes small signaling molecules along the LR axis that later regulate transcription of the normally left-sided Nodal. This system thus amplifies single cell chirality into a true left-right asymmetry across multi-cellular fields. Studies using molecular-genetic gain- and loss-of-function reagents have characterized many of the steps involved in this early pathway in Xenopus. Yet one key question remains: how is the chiral cytoskeletal architecture interpreted to localize ion transporters to the left or right side? Because Rab GTPases regulate nearly all aspects of membrane trafficking, we hypothesized that one or more Rab proteins were responsible for the directed, asymmetric shuttling of maternal ion channel or pump proteins. After performing a screen using dominant negative and wildtype (overexpressing) mRNAs for four different Rabs, we found that alterations in Rab11 expression randomize both asymmetric gene expression and organ situs. We also demonstrated that the asymmetric localization of two ion transporter subunits requires Rab11 function, and that Rab11 is closely associated with at least one of these subunits. Yet, importantly, we found that endogenous Rab11 mRNA and protein are expressed symmetrically in the early embryo. We conclude that Rab11-mediated transport is responsible for the movement of cargo within early blastomeres, and that Rab11 expression is required throughout the early embryo for proper LR patterning.

Oligomerization of rab/effector complexes in the regulation of vesicle trafficking

Rabs comprise the largest member of the Ras superfamily of small GTPases with over 60 proteins in mammals and 11 proteins in yeast. Like all small GTPases, Rabs oscillate between an inactive GDP-bound conformation and an active GTP-bound state that is tethered to lipid membranes via a C-terminal prenylation site on conserved cysteine residues. In their active state, Rabs regulate various aspects of membrane trafficking, including vesicle formation, transport, docking, and fusion. The critical element of biological activity is the recruitment of cytosolic effector proteins to specific endomembranes by active Rabs. The importance of Rabs in cellular processes is apparent from their links to genetic disorders, immunodeficiency, cancer, and pathogen invasion. During the last decade, numerous structures of complexes have shed light on the molecular basis for Rab/effector specificity and their topological organization on subcellular membranes. Here, I review the known structures of Rab/effector complexes and their modes of oligomerization. This is followed by a brief discussion on the thermodynamics of effector recruitment, which has not been documented sufficiently in previous reviews. A summary of diseases associated with Rab/effector trafficking pathways concludes this chapter.