Deregulation of Rab and Rab effector genes in bladder cancer

MICAL2 promotes breast cancer cell migration by maintaining epidermal growth factor receptor (EGFR) stability and EGFR/P38 signalling activation

AIM

MICAL2, a cytoskeleton dynamics regulator, is identified associated with survival and metastasis of several types of cancers recently. This study was designed to investigate the role of MICAL2 in breast cancer cell migration as well as its underlying mechanisms.

METHODS

The relationship between MICAL2 and EGF/EGFR signalling was analysed by gene overexpression and knock-down techniques. Cell migration was measured by wound-healing assays. Activation of EGF/EGFR signalling pathways were evaluated by immunofluorescence, qPCR, Western blotting and zymography techniques. Rac1 activity was assessed by pull-down assay. Correlation of MICAL2 and EGFR in breast cancer specimens was examined by immunohistochemical analysis.

RESULTS

Ectopic expression of MICAL2 in MCF-7 cells augmented EGFR protein level, accompanied by the promotion of cell migration. Silencing MICAL2 in MDA-MB-231 cells destabilized EGFR and inhibited cell migration. In mechanism, the maintaining effect of MICAL2 on EGFR protein content was due to a delay in EGFR degradation. Expression of MICAL2 was also shown positively correlated with the activation of P38/HSP27 and P38/MMP9 signallings, which are the main downstream signalling cascades of EGF/EGFR involved in cell migration. Further analysis indicated that Rac1 activation contributed to the maintaining effect of MICAL2 on EGFR stability. In addition, analysis of breast cancer specimens revealed a positive correlation between MICAL2 and EGFR levels and an association between MICAL2 expression and worse prognosis.

CONCLUSION

MICAL2 is a major regulator of breast cancer cell migration, maintaining EGFR stability and subsequent EGFR/P38 signalling activation through inhibiting EGFR degradation in a Rac1-dependent manner.

The MICALs are a Family of F-actin Dismantling Oxidoreductases Conserved from Drosophila to Humans

Cellular form and function – and thus normal development and physiology – are specified via proteins that control the organization and dynamic properties of the actin cytoskeleton. Using the Drosophila model, we have recently identified an unusual actin regulatory enzyme, Mical, which is directly activated by F-actin to selectively post-translationally oxidize and destabilize filaments – regulating numerous cellular behaviors. Mical proteins are also present in mammals, but their actin regulatory properties, including comparisons among different family members, remain poorly defined. We now find that each human MICAL family member, MICAL-1, MICAL-2, and MICAL-3, directly induces F-actin dismantling and controls F-actin-mediated cellular remodeling. Specifically, each human MICAL selectively associates with F-actin, which directly induces MICALs catalytic activity. We also find that each human MICAL uses an NADPH-dependent Redox activity to post-translationally oxidize actin’s methionine (M) M44/M47 residues, directly dismantling filaments and limiting new polymerization. Genetic experiments also demonstrate that each human MICAL drives F-actin disassembly in vivo, reshaping cells and their membranous extensions. Our results go on to reveal that MsrB/SelR reductase enzymes counteract each MICAL’s effect on F-actin in vitro and in vivo. Collectively, our results therefore define the MICALs as an important phylogenetically-conserved family of catalytically-acting F-actin disassembly factors.

Overexpression of MICAL2, a novel tumor-promoting factor, accelerates tumor progression through regulating cell proliferation and EMT

Molecule interacting with CasL 2 (MICAL2), a microtubule associated monooxygenase, is involved in cell growth, axon guidance, vesicle trafficking and apoptosis. Recent studies have demonstrated that MICAL2 is highly expressed in tumor and accelerates tumor progression and it is deemed to be a novel tumor-promoting factor. MICAL2 overexpression increases cell proliferation to accelerate tumor growth, and MICAL2 also promotes epithelial-mesenchymal transition (EMT)-related proteins to increase cancer cell metastasis. On mechanism, MICAL2 induces EMT by regulating SRF (serum response factor)/MRTF-A (myocardin related transcription factor A) signaling, Semaphorin/Plexin pathway and inducing ROS (Reactive oxygen species) production. In the present review, we introduced MICAL family, expatiated the structure and functions of MICALs, and summarized the mechanisms of MICAL2 involving tumor progression. The challenges and perspectives for MICAL2 in tumor are also discussed.

Consequences of Rab GTPase dysfunction in genetic or acquired human diseases

Rab GTPases are important regulators of intracellular membrane trafficking in eukaryotes. Both activating and inactivating mutations in Rab genes have been identified and implicated in human diseases ranging from neurological disorders to cancer. In addition, altered Rab expression is often associated with disease prognosis. As such, the study of diseases associated with Rabs or Rab-interacting proteins has shed light on the important role of intracellular membrane trafficking in disease etiology. In this review, we cover recent advances in the field with an emphasis on cellular mechanisms.

Collagen prolyl hydroxylase 3 has a tumor suppressive activity in human lung cancer

Collagen prolyl hydroxylases (P3H) are required for proper collagen biosynthesis. One of the family members P3H3 was downregulated in breast cancer and lymphoma due to DNA methylation. However the role of P3H3 in lung cancer has not yet been elucidated. In this study, we analyzed P3H3 expression in a panel of lung cancer cell lines and primary lung tumors. Epigenetic regulation was explored and the function of P3H3 was investigated by stable transfection and RNA interference. We found that P3H3 was downregulated in 6 out of 10 lung cancer cell lines. A heterogeneous methylation pattern of P3H3 was found in the exon region. In primary lung tumors, immunohistochemistry on tissue microarray (TMA) showed that higher expression of P3H3 was significantly associated with lower tumor N stage and grade (p = 0.035 and p = 0.026, respectively). Ectopic expression of P3H3 inhibited cell proliferation, colony formation, migration as well as invasion, and induced apoptosis together with cell cycle arrest in the G2/M phase. Knockdown of P3H3 led to increased migratory and invasive potential. These Phenomena are accompanied by enhanced p21, decreased cyclin A1 levels and increased caspase 3/7 activities. Taken together, we feel that P3H3 is a novel tumor suppressor and its protein expression is inversely related to lymph node metastasis and tumor differentiation in lung cancer.

Knockdown of Rab21 inhibits proliferation and induces apoptosis in human glioma cells

Background

Gliomas are commonly malignant tumors that arise in the human central nervous system and have a low overall five-year survival rate. Previous studies reported that several members of Rab GTPase family are involved in the development of glioma, and abnormal expression of Rab small GTPases is known to cause aberrant tumor cell behavior. In this study, we characterized the roles of Rab21 (Rab GTPase 21), a member of Rab GTPase family, in glioma cells.

Methods

The study involved downregulation of Rab21 in two glioma cell lines (T98G and U87) through transfection with specific-siRNA. Experiments using the MTT assay, cell cycle analysis, apoptosis assay, real-time PCR and western blot were performed to establish the expression levels of related genes.

Results

The results show that downregulation of Rab21 can significantly inhibit cell growth and remarkably induce cell apoptosis in T98G and U87 cell lines. Silencing Rab21 resulted in significantly increased expression of apoptosis-related proteins (caspase7, Bim and Bax) in glioma cells.

Conclusions

We inferred that Rab21 silencing can induce apoptosis and inhibit proliferation in human glioma cells, indicating that Rab21 might act as an oncogene and serve as a novel target for glioma therapy.

MiR-150 Inhibits Cell Growth In Vitro and In Vivo by Restraining the RAB11A/WNT/β-Catenin Pathway in Thyroid Cancer

Background

Emerging evidence has shown that downregulation or upregulation of microRNAs (miRNAs) plays an important role in the development and progression of thyroid cancer (TC). However, the potential role of miR-150 and its biological function in TC remains largely unclear.

Material/Methods

Real-time polymerase chain reaction (RT-qPCR) was employed to detect the expression level of miR-150 and RAB11A in human TC tissue and human normal thyroid tissue. MTT assay, colony formation assay, flow cytometry cell cycle, and apoptosis assay were used to investigate the role of miR-150 and RAB11A on the malignant phenotypes in vitro. Nude mouse xenograft assay and western blot assay was used to verify the function of miR-150 in vivo. Western blot assay and immunofluorescence assay were used to detect the activation of WNT/β-catenin pathway mediated by miR-150 and RAB11A. EGFP reporter assay, RT-qPCR assay, and western blot assay were used to validate the regulation relationship.

Results

This study demonstrated that miR-150 expression in human TC tissues was markedly downregulated. Moreover, overexpression of miR-150 markedly inhibited cell proliferation via inducing the cell cycle arrest and promoting cell apoptosis by directly targeting RAB11A in vitro and suppressing tumor growth in vivo. However, overexpression of RAB11A promoted cell malignant phenotypes. In addition, miR-150 restrained the RAB11A mediated WNT/β-catenin activation in TC cells.

Conclusions

miR-150 may function as a suppressor gene in TC cells by inhibiting the RAB11A/WNT/β-catenin pathway.

Decreased expression of Zwint-1 is associated with poor prognosis in hepatocellular carcinoma

BACKGROUND AND AIM

ZW10 interacting kinetochore protein 1 (Zwint-1), one of the major kinetochore proteins, is essential for kinetochore function, such as spindle assembly checkpoint function and kinetochore-microtubule attachment. Recently, it has been found over-expressed in some human cancers, including ovarian cancer, bladder cancer, and pulmonary adenocarcinoma. However, few studies of the expression of Zwint-1 in hepatocellular carcinoma (HCC) have been reported. This study is aimed to investigate the expression of Zwint-1 and its relationship with clinical pathological characters in HCC.

METHODS

The expression of Zwint-1 protein was analyzed by immunohistochemistry staining on tissue microarrays containing 171 HCC tissues and 187 control non-tumorous liver tissues. The relationships between the Zwint-1 expression and the clinicopathological parameters, and survival analysis were investigated using SPSS software 13.0.

RESULTS

Zwint-1 was found uniformly expressed in adjacent non-tumorous liver tissues (184/187, 98.40%), while was significantly decreased in HCC tissues, or even absent (150 of 171, 61.82%, P<0.001). The expression of Zwint-1 was negatively associated with age, tumor size, and Edmondson Grade. Besides, HCC patients with low Zwint-1 expression were also correlated with poor overall survival of the patients.

CONCLUSIONS

Decreased expression of Zwint-1 was associated with poor prognosis in HCC.

Effects of Rab27A and Rab27B on Invasion, Proliferation, Apoptosis, and Chemoresistance in Human Pancreatic Cancer Cells

OBJECTIVES

Rab family members are key regulatory factors that function as molecular switches in multiple phases of vesicular trafficking. Our previous study demonstrated that Rab27A and Rab27B overexpression may predict a poor outcome of pancreatic ductal adenocarcinoma. The purpose of this study was to investigate the role of Rab27A and Rab27B in the progression of pancreatic cancer.

METHODS

We down-regulated Rab27A and Rab27B expression in pancreatic cancer cell lines. The regulatory effects of knockdown Rab27A and Rab27B on pancreatic cancer cell were measured by cisplatin assay, invasion assay, proliferation assay, and Western blot assay.

RESULTS

Rab27A and Rab27B down-regulation enhances sensitivity to cisplatin and induces apoptosis in ASPC-1 and PANC-1 cells. In addition, down-regulation of Rab27A reduced the invasive and proliferative ability of ASPC-1 cells, and Rab27B knockdown significantly prevented cancer invasion and proliferation in PANC-1 cells.

CONCLUSIONS

Our findings provide evidence that Rab27A and Rab27B play significant roles in cell invasion, proliferation, and apoptosis, as well as in chemotherapy resistance.

Identification of CEA-interacting proteins in colon cancer cells and their changes in expression after irradiation

Purpose

The serum carcinoembryonic antigen (CEA) level has been recognized as a prognostic factor in colorectal cancer, and associated with response of rectal cancer to radiotherapy. This study aimed to identify CEA-interacting proteins in colon cancer cells and observe post-irradiation changes in their expression.

Materials and Methods

CEA expression in colon cancer cells was examined by Western blot analysis. Using an anti-CEA antibody or IgG as a negative control, immunoprecipitation was performed in colon cancer cell lysates. CEA and IgG immunoprecipitates were used for liquid chromatography–tandem mass spectrometry (LC-MS/MS) analysis. Proteins identified in the CEA immunoprecipitates but not in the IgG immunoprecipitates were selected as CEA-interacting proteins. After radiation treatment, changes in expression of CEA-interacting proteins were monitored by Western blot analysis.

Results

CEA expression was higher in SNU-81 cells compared with LoVo cells. The membrane localization of CEA limited the immunoprecipitation results and thus the number of CEA-interacting proteins identified. Only the Ras-related protein Rab-6B and lysozyme C were identified as CEA-interacting proteins in LoVo and SNU-81 cells, respectively. Lysozyme C was detected only in SNU-81, and CEA expression was differently regulated in two cell lines; it was down-regulated in LoVo but up-regulated in SNU-81 in radiation dosage-dependent manner.

Conclusion

CEA-mediated radiation response appears to vary, depending on the characteristics of individual cancer cells. The lysozyme C and Rab subfamily proteins may play a role in the link between CEA and tumor response to radiation, although further studies are needed to clarify functional roles of the identified proteins.

Whole-Exome Sequencing Study of Thyrotropin-Secreting Pituitary Adenomas

CONTEXT

Thyrotropin (TSH)-secreting pituitary adenomas (TSHomas) are a rare cause of hyperthyroidism, and the genetic aberrations responsible remain unknown.

OBJECTIVE

To identify somatic genetic abnormalities in TSHomas.

DESIGN AND SETTING

A single-nucleotide polymorphism (SNP) array analysis was performed on 8 TSHomas. Four tumors with no allelic losses or limited loss of heterozygosity were selected, and whole-exome sequencing was performed, including their corresponding blood samples. Somatic variants were confirmed by Sanger sequencing. A set of 8 tumors was also assessed to validate candidate genes.

PATIENTS

Twelve patients with sporadic TSHomas were examined.

RESULTS

The overall performance of whole-exome sequencing was good, with an average coverage of each base in the targeted region of 97.6%. Six DNA variants were confirmed as candidate driver mutations, with an average of 1.5 somatic mutations per tumor. No mutations were recurrent. Two of these mutations were found in genes with an established role in malignant tumorigenesis (SMOX and SYTL3), and 4 had unknown roles (ZSCAN23, ASTN2, R3HDM2, and CWH43). Similarly, an SNP array analysis revealed frequent chromosomal regions of copy number gains, including recurrent gains at loci harboring 4 of these 6 genes.

CONCLUSIONS

Several candidate somatic mutations and changes in copy numbers for TSHomas were identified. The results showed no recurrence of mutations in the tumors studied but a low number of mutations, thereby highlighting their benign nature. Further studies on a larger cohort of TSHomas, along with the use of epigenetic and transcriptomic approaches, may reveal the underlying genetic lesions.

Overexpression of Kinesin Family Member 20A Correlates with Disease Progression and Poor Prognosis in Human Nasopharyngeal Cancer: A Retrospective Analysis of 105 Patients

BACKGROUND

Numerous studies have shown Kinesin family member 20A (KIF20A) may play a critical role in the development and progression of cancer. However, the clinical value of KIF20A in nasopharyngeal carcinoma (NPC) is unknown. Here, we investigated the expression pattern of KIF20A in NPC and its correlation with clinicopathological features of patients.

METHODS

Real-time PCR and Western blotting were used to quantify KIF20A expression in NPC cell lines and clinical specimens compared with normal controls. KIF20A protein expression was also examined in archived paraffin embedded tumor samples from 105 patients with pathologically confirmed NPC by immunohistochemistry (IHC). Statistical analyses were applied to assess the associations between KIF20A expression and the clinicopathological features and survival outcomes. Effects on migration and invasion were assessed by wound healing and transwell invasion assays after KIF20A silencing.

RESULTS

KIF20A was significantly overexpressed at both the mRNA and protein levels in NPC cell lines and human tumor tissues. 45/105 (42.9%) of NPC specimens expressed high levels of KIF20A among the KIF20A detectable cases. Statistical analysis revealed that high KIF20A expression was significantly associated with gender (P = 0.046), clinical stage (P<0.001), T category (P = 0.022), N category (P<0.001), distant metastasis (P = 0.001) and vital status (P = 0.001). Moreover, Higher KIF20A expression patients had shorter overall survival (OS) and progression-free survival (PFS) (P = 0.001 and P = 0.001; log-rank test). In multivariate analysis, KIF20A was an independent prognostic factor for OS and PFS in the entire cohort (P = 0.033, P = 0.008). Knock down of KIF20A expression significantly suppressed NPC cell's migration and invasion.

CONCLUSIONS

KIF20A is overexpressed and may serve as an independent prognostic biomarker in NPC. Targeting KIF20A reduces migration and invasion of NPC cells.

High Expression of KIF20A Is Associated with Poor Overall Survival and Tumor Progression in Early-Stage Cervical Squamous Cell Carcinoma

Background

The kinesin family member 20a (KIF20A) protein has been implicated in the development and progression of many human cancers; however, its precise function and role in cervical cancer remain largely unclear. This study aimed to investigate the expression profile and prognostic value of KIF20A in patients with early-stage cervical squamous cell carcinoma.

Methods

We examined the mRNA and protein levels of KIF20A in eight cervical cancer cell lines and eight paired cervical cancer samples, compared with normal cervical epithelial cells and adjacent normal cervical tissues, respectively. Immunohistochemistry was performed to detect the expression of KIF20A in paraffin-embedded specimens from 169 early-stage cervical squamous cell carcinoma patients. Statistical analyses were applied to analyze the association between KIF20A expression and clinical variables, as well with patient survival.

Results

The mRNA and protein expression levels of KIF20A were significantly elevated in cervical cancer cell lines and lesions compared with normal cells and corresponding normal tissues (P < 0.05). Immunohistochemistry analysis in 169 cervical cancer cases revealed that increased KIF20A expression was strongly associated with human papillomavirus (HPV) infection (P = 0.008), clinical stage (P = 0.001), tumor recurrence (P = 0.016), vital status (P < 0.001), the property of the surgical margin (P = 0.032), the lymphovascular space involvement (P = 0.014), and pelvic lymph node metastasis (P = 0.001). The overall survival and disease-free survival of patients with high levels of KIF20A expression were significantly poorer than those with low KIF20A expression. KIF20A was an independent survival prognostic factor, as evidenced by univariate and multivariate analysis.

Conclusions

Our results illustrate that elevated KIF20A expression correlates with HPV infection, clinical stage, tumor recurrence, lymphovascular space involvement, pelvic lymph node metastasis, and poor outcome in early-stage cervical squamous cell carcinoma patients. KIF20A aberrant expression is a novel independent unfavorable prognostic factor and may present a potential therapeutic target for cervical cancer.

Rab14 is overexpressed in ovarian cancers and promotes ovarian cancer proliferation through Wnt pathway

The Rab GTPase family protein Rab14 has been implicated in cancer development. However, its clinical significance in ovarian cancers and its biological effects have not been examined. The present study aims to examine the clinical significance, biological roles, and molecular mechanism of Rab14 in ovarian cancer progression. We examined expression pattern of Rab14 in 122 cases of ovarian cancer specimens using immunohistochemistry and found Rab14 overexpression correlated with FIGO stage (p = 0.0041). We depleted Rab14 in SKOV3 cells using siRNA and overexpressed Rab14 in SW626 cells. Knockdown of Rab14 inhibited cell growth and invasion while its overexpression facilitated cell growth and invasion. In addition, Rab14 overexpression increased paclitaxel resistance in SW626 cells while its depletion reduced drug resistance. Then, we investigated the role of Rab14 in the regulation of WNT/β-catenin signaling, demonstrating Rab14 overexpression regulated GSK3β phosphorylation and nuclear β-catenin accumulation. Rab14 depletion inhibited while its overexpression enhanced TCF transcriptional activity with corresponding change of Wnt target genes including MMP7 and c-myc. Wnt inhibitor abolished the effect of Rab14 on cell proliferation and Wnt target genes. In conclusion, the present study demonstrated that Rab14 promotes aggressiveness of ovarian cancer cell through, at least partly, Wnt signaling pathway.

Actin filaments-A target for redox regulation

Actin and its ability to polymerize into dynamic filaments is critical for the form and function of cells throughout the body. While multiple proteins have been characterized as affecting actin dynamics through noncovalent means, actin and its protein regulators are also susceptible to covalent modifications of their amino acid residues. In this regard, oxidation-reduction (Redox) intermediates have emerged as key modulators of the actin cytoskeleton with multiple different effects on cellular form and function. Here, we review work implicating Redox intermediates in post-translationally altering actin and discuss what is known regarding how these alterations affect the properties of actin. We also focus on two of the best characterized enzymatic sources of these Redox intermediates-the NADPH oxidase NOX and the flavoprotein monooxygenase MICAL-and detail how they have both been identified as altering actin, but share little similarity and employ different means to regulate actin dynamics. Finally, we discuss the role of these enzymes and redox signaling in regulating the actin cytoskeleton in vivo and highlight their importance for neuronal form and function in health and disease. © 2016 Wiley Periodicals, Inc.

Cortactin promotes exosome secretion by controlling branched actin dynamics

Exosomes are extracellular vesicles that influence cellular behavior and enhance cancer aggressiveness by carrying bioactive molecules. The mechanisms that regulate exosome secretion are poorly understood. Here, we show that the actin cytoskeletal regulatory protein cortactin promotes exosome secretion. Knockdown or overexpression of cortactin in cancer cells leads to a respective decrease or increase in exosome secretion, without altering exosome cargo content. Live-cell imaging revealed that cortactin controls both trafficking and plasma membrane docking of multivesicular late endosomes (MVEs). Regulation of exosome secretion by cortactin requires binding to the branched actin nucleating Arp2/3 complex and to actin filaments. Furthermore, cortactin, Rab27a, and coronin 1b coordinately control stability of cortical actin MVE docking sites and exosome secretion. Functionally, the addition of purified exosomes to cortactin-knockdown cells rescued defects of those cells in serum-independent growth and invasion. These data suggest a model in which cortactin promotes exosome secretion by stabilizing cortical actin-rich MVE docking sites.

Distinct Biochemical Pools of Golgi Phosphoprotein 3 in the Human Breast Cancer Cell Lines MCF7 and MDA-MB-231

Golgi phosphoprotein 3 (GOLPH3) has been implicated in the development of carcinomas in many human tissues, and is currently considered a bona fide oncoprotein. Importantly, several tumor types show overexpression of GOLPH3, which is associated with tumor progress and poor prognosis. However, the underlying molecular mechanisms that connect GOLPH3 function with tumorigenicity are poorly understood. Experimental evidence shows that depletion of GOLPH3 abolishes transformation and proliferation of tumor cells in GOLPH3-overexpressing cell lines. Conversely, GOLPH3 overexpression drives transformation of primary cell lines and enhances mouse xenograft tumor growth in vivo. This evidence suggests that overexpression of GOLPH3 could result in distinct features of GOLPH3 in tumor cells compared to that of non-tumorigenic cells. GOLPH3 is a peripheral membrane protein mostly localized at the trans-Golgi network, and its association with Golgi membranes depends on binding to phosphatidylinositol-4-phosphate. GOLPH3 is also contained in a large cytosolic pool that rapidly exchanges with Golgi-associated pools. GOLPH3 has also been observed associated with vesicles and tubules arising from the Golgi, as well as other cellular compartments, and hence it has been implicated in several membrane trafficking events. Whether these and other features are typical to all different types of cells is unknown. Moreover, it remains undetermined how GOLPH3 acts as an oncoprotein at the Golgi. Therefore, to better understand the roles of GOLPH3 in cancer cells, we sought to compare some of its biochemical and cellular properties in the human breast cancer cell lines MCF7 and MDA-MB-231 with that of the non-tumorigenic breast human cell line MCF 10A. We found unexpected differences that support the notion that in different cancer cells, overexpression of GOLPH3 functions in diverse fashions, which may influence specific tumorigenic phenotypes.

Novel non invasive diagnostic strategies in bladder cancer

Bladder cancer is one of the most commonly diagnosed malignancies worldwide, derived from the urothelium of the urinary bladder and defined by long asymptomatic and atypical clinical picture. Its complex etiopathogenesis is dependent on numerous risk factors that can be divided into three distinct categories: genetic and molecular abnormalities, chemical or environmental exposure and previous genitourinary disorders and family history of different malignancies. Various genetic polymorphisms and microRNA might represent useful diagnostic or prognostic biomarkers. Genetic and molecular abnormalities - risk factors are represented by miRNA or genetic polymorphisms proved to be part of bladder carcinogenesis such as: genetic mutations of oncogenes TP53, Ras, Rb1 or p21 oncoproteins, cyclin D or genetic polymorhisms of XPD,ERCC1, CYP1B1, NQO1C609T, MDM2SNP309, CHEK2, ERCC6, NRF2, NQO1Pro187Ser polymorphism and microRNA (miR-143, −145, −222, −210, −10b, 576-3p). The aim of our article is to highlight the most recent acquisitions via molecular biomarkers (miRNAs and genetic polymorphisms) involved in bladder cancer in order to provide early diagnosis, precise therapy according to the molecular profile of bladder tumors, as well as to improve clinical outcome, survival rates and life quality of oncological patients. These molecular biomarkers play a key role in bladder carcinogenesis, clinical evolution, prognosis and therapeutic response and explain the molecular mechanisms involved in bladder carcinogenesis; they can also be selected as therapeutic targets in developing novel therapeutic strategies in bladder malignancies. Moreover, the purpose in defining these molecular non invasive biomarkers is also to develop non invasive screening programs in bladder malignancies with the result of decreasing bladder cancer incidence in risk population.

Identification of novel genes that regulate androgen receptor signaling and growth of androgen-deprived prostate cancer cells

Prostate cancer progression to castration refractory disease is associated with anomalous transcriptional activity of the androgen receptor (AR) in an androgen-depleted milieu. To identify novel gene products whose downregulation transactivates AR in prostate cancer cells, we performed a screen of enzymatically-generated shRNA lenti-libraries selecting for transduced LNCaP cells with elevated expression of a fluorescent reporter gene under the control of an AR-responsive promoter. The shRNAs present in selected populations were analyzed using high-throughput sequencing to identify target genes. Highly enriched gene targets were then validated with siRNAs against selected genes, testing first for increased expression of luciferase from an AR-responsive promoter and then for altered expression of endogenous androgen-regulated genes in LNCaP cells. We identified 20 human genes whose silencing affected the expression of exogenous and endogenous androgen-responsive genes in prostate cancer cells grown in androgen-depleted medium. Knockdown of four of these genes upregulated the expression of endogenous AR targets and siRNAs targeting two of these genes (IGSF8 and RTN1) enabled androgen-independent proliferation of androgen-dependent cells. The effects of IGSF8 appear to be mediated through its interaction with a tetraspanin protein, CD9, previously implicated in prostate cancer progression. Remarkably, homozygous deletions of IGSF8 are found almost exclusively in prostate cancers but not in other cancer types. Our study shows that androgen independence can be achieved through the inhibition of specific genes and reveals a novel set of genes that regulate AR signaling in prostate cancers.

Small RAB GTPases Regulate Multiple Steps of Mitosis

GTPases of the RAB family are key regulators of multiple steps of membrane trafficking. Several members of the RAB GTPase family have been implicated in mitotic progression. In this review, we will first focus on the function of endosome-associated RAB GTPases reported in early steps of mitosis, spindle pole maturation, and during cytokinesis. Second, we will discuss the role of Golgi-associated RAB GTPases at the metaphase/anaphase transition and during cytokinesis.

Correlation Between RAB27B and p53 Expression and Overall Survival in Pancreatic Cancer

OBJECTIVES

RAB27B is a member of the Rab family GTPases involved in vesicle trafficking, and p53 has recently been implicated in regulating the exosome secretion pathway. Because exosome secretion plays an important role in modulating tumor microenvironment and invasive growth, we hypothesized that RAB27B and p53 expression might be associated with the aggressive behavior in pancreatic ductal adenocarcinoma, one of the most deadly human malignancies.

METHODS

We determined protein expression of RAB27B and p53 in 260 pancreatic tissues (186 malignant and 74 normal or benign) by immunohistochemistry analysis on tissue microarray and their correlation with patients' clinical parameters and overall survival.

RESULTS

We found that a high RAB27B protein expression (RAB27B) was significantly associated with perineural and vascular invasion, as well as distant metastasis. Patients with a high RAB27B expression had significantly poorer overall survival in both univariate and multivariate analyses. A significant correlation between RAB27B and p53 expression was observed.

CONCLUSIONS

Our data indicate that RAB27B expression is an independent prognostic marker for pancreatic ductal adenocarcinoma and suggest that RAB27B-regulated exosome secretion pathway represents a novel therapeutic target in pancreatic cancer.

Rab23 is overexpressed in human bladder cancer and promotes cancer cell proliferation and invasion

Rab23 overexpression has been implicated in several human cancers. However, its expression pattern and biological roles in human bladder cancer have not been elucidated. In this study, we examined Rab23 expression in 93 bladder cancer specimens and analyzed its correlation with clinicopathological parameters. We found that Rab23 was overexpressed in 45 of 93 (48.3 %) cancer specimens. Significant association was found between Rab23 overexpression and tumor invasion depth (p = 0.0027). Rab23 overexpression also negatively correlated with FGFR3 protein expression (p = 0.021). We found that Rab23 expression was lower in normal bladder transitional cell line SV-HUC-1 than in bladder cancer cell lines BIU-87, 5637, and T24. We knocked down Rab23 expression in T24 cancer cells and transfected a Rab23 plasmid in the BIU-87 cell line. Rab23 depletion inhibited cell growth rate and invasion, while its overexpression resulted in increased cell growth and invasion. In addition, we demonstrated that Rab23 depletion decreased and its transfection upregulated expression of cyclin E, c-myc, and MMP-9. Furthermore, we showed that Rab23 knockdown inhibited NF-κB signaling and its overexpression upregulated NF-κB signaling. BAY 11-7082 (NF-κB inhibitor) partly inhibited the effect of Rab23 on cyclin E and MMP-9 expression. In conclusion, the present study demonstrated that Rab23 overexpression facilitates malignant cell growth and invasion in bladder cancer through the NF-κB pathway.

New MKLP-2 inhibitors in the paprotrain series: Design, synthesis and biological evaluations

Members of the kinesin superfamily are involved in key functions during intracellular transport and cell division. Their involvement in cell division makes certain kinesins potential targets for drug development in cancer chemotherapy. The two most advanced kinesin targets are Eg5 and CENP-E with inhibitors in clinical trials. Other mitotic kinesins are also being investigated for their potential as prospective drug targets. One recently identified novel potential cancer therapeutic target is the Mitotic kinesin-like protein 2 (MKLP-2), a member of the kinesin-6 family, which plays an essential role during cytokinesis. Previous studies have shown that inhibition of MKLP-2 leads to binucleated cells due to failure of cytokinesis. We have previously identified compound 1 (paprotrain) as the first selective inhibitor of MKLP-2. Herein we describe the synthesis and biological evaluation of new analogs of 1. Our structure-activity relationship (SAR) study reveals the key chemical elements in the paprotrain family necessary for MKLP-2 inhibition. We have successfully identified one MKLP-2 inhibitor 9a that is more potent than paprotrain. In addition, in vitro analysis of a panel of kinesins revealed that this compound is selective for MKLP-2 compared to other kinesins tested and also does not have an effect on microtubule dynamics. Upon testing in different cancer cell lines, we find that the more potent paprotrain analog is also more active than paprotrain in 10 different cancer cell lines. Increased selectivity and higher potency is therefore a step forward toward establishing MKLP-2 as a potential cancer drug target.

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.

Cellular functions of Rab GTPases at a glance

Rab GTPases control intracellular membrane traffic by recruiting specific effector proteins to restricted membranes in a GTP-dependent manner. In this Cell Science at a Glance and the accompanying poster, we highlight the regulation of Rab GTPases by proteins that control their membrane association and activation state, and provide an overview of the cellular processes that are regulated by Rab GTPases and their effectors, including protein sorting, vesicle motility and vesicle tethering. We also discuss the physiological importance of Rab GTPases and provide examples of diseases caused by their dysfunctions.

Clinical Implications of Rabphillin-3A-Like Gene Alterations in Breast Cancer

For the rabphillin-3A-like (RPH3AL) gene, a putative tumor suppressor, the clinical significance of genetic alterations in breast cancers was evaluated. DNA and RNA were extracted from formalin-fixed, paraffin-embedded (FFPE) cancers and matching normal tissues. DNA samples were assessed for loss of heterozygosity (LOH) at the 17p13.3 locus of RPH3AL and the 17p13.1 locus of the tumor suppressor, TP53. RPH3AL was sequenced, and single nucleotide polymorphisms (SNPs) were genotyped. RNA samples were evaluated for expression of RPH3AL, and FFPE tissues were profiled for its phenotypic expression. Alterations in RPH3AL were correlated with clinicopathological features, LOH of TP53, and patient survival. Of 121 cancers, 80 had LOH at one of the RPH3AL locus. LOH of RHP3AL was associated with nodal metastasis, advanced stage, large tumor size, and poor survival. Although ~50% were positive for LOH at the RPH3AL and TP53 loci, 19 of 105 exhibited LOH only at the RPH3AL locus. Of these, 12 were non-Hispanic Caucasians (Whites), 15 had large tumors, and 12 were older (>50 years). Patients exhibiting LOH at both loci had shorter survival than those without LOH at these loci (log-rank, P = 0.014). LOH at the TP53 locus alone was not associated with survival. Analyses of RPH3AL identified missense point mutations in 19 of 125 cases, a SNP (C>A) in the 5’untranslated region at -25 (5’UTR-25) in 26 of 104, and a SNP (G>T) in the intronic region at 43 bp downstream to exon-6 (intron-6-43) in 79 of 118. Genotype C/A or A/A of the SNP at 5’UTR-25 and genotype T/T of a SNP at intron-6-43 were predominantly in Whites. Low levels of RNA and protein expression of RPH3AL were present in cancers relative to normal tissues. Thus, genetic alterations in RPH3AL are associated with aggressive behavior of breast cancers and with short survival of patients.

Kif20a inhibition reduces migration and invasion of pancreatic cancer cells

BACKGROUND

The Translational Genome Research Network in Pancreatic Cancer performed a meta-analysis of publicly available various high-throughput gene analysis panels to identify drugable targets. There, the most differentially expressed gene between normal and cancerous pancreas was Kif20a. The aim of the study was to verify this expression pattern and further characterize Kif20a in pancreatic cancer.

MATERIALS AND METHODS

Detailed expression analyses were carried out in pancreatic tissues and in a wide panel of pancreatic cells including ductal adenocarcinoma (PDAC) and neuroendocrine-cancer cell lines as well as immortalized human pancreatic ductal epithelial and primary stellate cells using quantitative real-time polymerase chain reaction, immunohistochemistry, immunofluorescence, and immunoblot analyses. Effects on proliferation, apoptosis, and cell cycle were assessed by MTT assays, caspase-cleavage assays, and fluorescence-activated cell sorting analysis after Kif20a silencing. Cell motility was assessed by migration and invasion assays as well as time-lapse microscopy.

RESULTS

Mean Kif20a messenger RNA expression was 18.4-fold upregulated in PDAC tissues compared with that in the normal pancreas. In line, neuroendocrine-cancer cell lines display a 1.6-fold increase and ductal adenocarcinoma cell lines a 11-fold increase of Kif20a messenger RNA (P = 0.009) in comparison with primary stellate cells. A 7.3-fold overexpression was also found in immortalized pancreatic ductal epithelial cells. Kif20a silencing with small interfering RNA molecules resulted in an inhibition of proliferation, motility, and invasion of pancreatic cancer cell lines.

CONCLUSIONS

Targeting Kif20a reduces proliferation, migration, and invasion of pancreatic cancer cells. Together with its significant overexpression in PDAC, this makes it a potential target for diagnostic and interventional purposes.

Small GTPase Rab21 mediates fibronectin induced actin reorganization in Entamoeba histolytica: implications in pathogen invasion

The protozoan parasite Entamoeba histolytica causes a wide spectrum of intestinal infections. In severe cases, the trophozoites can breach the mucosal barrier, invade the intestinal epithelium and travel via the portal circulation to the liver, where they cause hepatic abscesses, which can prove fatal if left untreated. The host Extra Cellular Matrix (ECM) plays a crucial role in amoebic invasion by triggering an array of cellular responses in the parasite, including induction of actin rich adhesion structures. Similar actin rich protrusive structures, known as 'invadosomes', promote chemotactic migration of the metastatic cancer cells and non-transformed cells by remodeling the ECM. Recent studies showed a central role for Rab GTPases, the master regulators of vesicular trafficking, in biogenesis of invadosomes. Here, we showed that fibronectin, a major host ECM component induced actin remodeling in the parasite in a Rab21 dependent manner. The focalized actin structures formed were reminiscent of the mammalian invadosomes. By using various approaches, such as immunofluorescence confocal microscopy and scanning electron microscopy, along with in vitro invasion assay and matrix degradation assay, we show that the fibronectin induced formation of amoebic actin dots depend on the nucleotide status of the GTPase. The ECM components, fibronectin and collagen type I, displayed differential control over the formation of actin dots, with fibronectin positively and collagen type I negatively modulating it. The cell surface adhesion molecule Gal/GalNAc complex was also found to impose additional regulation on this process, which might have implication in collagen type I mediated suppression of actin dots.

The multiple cellular functions of the oncoprotein Golgi phosphoprotein 3

The highly conserved Golgi phosphoprotein 3 (GOLPH3) protein, a component of Trans-Golgi Network (TGN), has been defined as a "first-in-class Golgi oncoprotein" and characterized as a Phosphatidylinositol 4-phosphate [PI(4)P] effector at the Golgi. GOLPH3 is commonly amplified in several solid tumors. Furthermore this protein has been associated with poor prognosis in many cancers. Highly conserved from yeast to humans, GOLPH3 provides an essential function in vesicle trafficking and Golgi structure. Recent data have also implicated this oncoprotein in regulation of cytokinesis, modulation of mitochondrial mass and cellular response to DNA damage. A minute dissection of the molecular pathways that require GOLPH3 protein will be helpful to develop new therapeutic cancer strategies.

High expression of RAB27A and TP53 in pancreatic cancer predicts poor survival

RAB27A is a member of Rab family GTPases involved in cellular vesicle trafficking, and TP53 has recently been implicated in regulating the exosome secretion pathway. Because exosome secretion plays an important role in modulating tumor microenvironment and invasive growth, we hypothesized that RAB27A and TP53 expression might be associated with aggressive behavior in pancreatic ductal adenocarcinoma (PDAC), one of the most deadly human malignancies. We determined protein expression of RAB27A and TP53 in 265 pancreatic tissues (186 carcinomas and 79 normal or benign tissues) by immunohistochemistry analysis on tissue microarray and found their expression was correlated with patients' clinical parameters and overall survival. We found that RAB27A and TP53 protein expression was significantly higher in cancerous tissues compared to normal and benign tissues. High RAB27A protein expression (RAB27A+) was significantly associated with tumor stage and vascular invasion. No correlation between RAB27A and TP53 expression was observed. Patients with high RAB27A expression and high TP53 expression had a poor overall survival. Our data indicate that RAB27A expression is an independent prognostic marker for PDAC, and RAB27A-regulated exosome secretion pathway may represent a novel therapeutic target in pancreatic cancer .

High RAB25 expression is associated with good clinical outcome in patients with locally advanced head and neck squamous cell carcinoma

Currently there are no molecular markers able to predict clinical outcome in locally advanced head and neck squamous cell carcinoma (HNSCC). In a previous microarray study, RAB25 was identified as a potential prognostic marker. The aim of this study was to analyze the association between RAB25 expression and clinical outcome in patients with locally advanced HNSCC treated with standard therapy. In a retrospective immunohistochemical study (n = 97), we observed that RAB25-negative tumors had lower survival (log-rank, P = 0.01) than patients bearing positive tumors. In an independent prospective mRNA study (n = 117), low RAB25 mRNA expression was associated with poor prognosis. Using classification and regression tree analysis (CART) we established two groups of patients according to their RAB25 mRNA level and their risk of death. Low mRNA level was associated with poor local recurrence-free (log-rank, P = 0.005), progression-free (log-rank, P = 0.002) and cancer-specific (log-rank, P < 0.001) survival. Multivariate Cox model analysis showed that low expression of RAB25 was an independent poor prognostic factor for survival (hazard ratio: 3.84, 95% confidence interval: 1.93-7.62, P < 0.001). Patients whose tumors showed high RAB25 expression had a low probability of death after treatment. We also found lower RAB25 expression in tumors than in normal tissue (Mann-Whitney U, P < 0.001). Moreover, overexpression of RAB25 in the UM-SCC-74B HNSCC cell line increased cisplatin sensitivity, and reduced cell migration and invasion. Our findings support a tumor suppressor role for RAB25 in HNSCC and its potential use to identify locally advanced patients with a high probability of survival after genotoxic treatment.

Spire-1 contributes to the invadosome and its associated invasive properties

Cancer cells have an increased ability to squeeze through extracellular matrix gaps that they create by promoting proteolysis of its components. Major sites of degradation are specialized micro-domains in the plasma membrane collectively named invadosomes where the Arp2/3 complex and formin proteins cooperate to spatio-temporally control actin nucleation and the folding of a dynamic F-actin core. At invadosomes, proper coupling of exo-endocytosis allows polarized delivery of proteases that facilitate degradation of ECM and disruption of the cellular barrier. We investigated the contribution of the actin nucleator Spire-1 to invadosome structure and function, using Src-activated cells and cancer cells. We found that Spire-1 is specifically recruited at invadosomes and is part of a multi-molecular complex containing Src kinase, the formin mDia1 and actin. Spire-1 interacts with the Rab3A GTPase, a key player in the regulation of exocytosis that is present at invadosomes. Finally, over- and under-expression of Spire-1 resulted in cells with an increased or decreased potential for matrix degradation, respectively, therefore suggesting a functional interplay of Spire-1 with both actin nucleation and vesicular trafficking that might impact on cell invasive and metastatic behavior.

A central role for vesicle trafficking in epithelial neoplasia: intracellular highways to carcinogenesis

Epithelial cell carcinogenesis involves the loss of cell polarity, alteration of polarized protein presentation, dynamic cell morphology changes, increased proliferation, and increased cell motility and invasion. Membrane vesicle trafficking underlies all of these processes. Specific membrane trafficking regulators, including RAB small GTPases, through the coordinated dynamics of intracellular trafficking along cytoskeletal pathways, determine the cell surface presentation of proteins and the overall function of both differentiated and neoplastic cells. Although mutations in vesicle trafficking proteins may not be direct drivers of transformation, components of the machinery of vesicle movement have crucial roles in the phenotypes of neoplastic cells. Therefore, the regulators of membrane vesicle trafficking decisions are essential mediators of the full range of cell physiologies that drive cancer cell biology, including initial loss of cell polarity, invasion and metastasis. Targeting of these fundamental intracellular processes may permit the manipulation of cancer cell behaviour.

Integrative modelling of the influence of MAPK network on cancer cell fate decision

The Mitogen-Activated Protein Kinase (MAPK) network consists of tightly interconnected signalling pathways involved in diverse cellular processes, such as cell cycle, survival, apoptosis and differentiation. Although several studies reported the involvement of these signalling cascades in cancer deregulations, the precise mechanisms underlying their influence on the balance between cell proliferation and cell death (cell fate decision) in pathological circumstances remain elusive. Based on an extensive analysis of published data, we have built a comprehensive and generic reaction map for the MAPK signalling network, using CellDesigner software. In order to explore the MAPK responses to different stimuli and better understand their contributions to cell fate decision, we have considered the most crucial components and interactions and encoded them into a logical model, using the software GINsim. Our logical model analysis particularly focuses on urinary bladder cancer, where MAPK network deregulations have often been associated with specific phenotypes. To cope with the combinatorial explosion of the number of states, we have applied novel algorithms for model reduction and for the compression of state transition graphs, both implemented into the software GINsim. The results of systematic simulations for different signal combinations and network perturbations were found globally coherent with published data. In silico experiments further enabled us to delineate the roles of specific components, cross-talks and regulatory feedbacks in cell fate decision. Finally, tentative proliferative or anti-proliferative mechanisms can be connected with established bladder cancer deregulations, namely Epidermal Growth Factor Receptor (EGFR) over-expression and Fibroblast Growth Factor Receptor 3 (FGFR3) activating mutations.

Depending on environmental conditions, strongly intertwined cellular signalling pathways are activated, involving activation/inactivation of proteins and genes in response to external and/or internal stimuli. Alterations of some components of these pathways can lead to wrong cell behaviours. For instance, cancer-related deregulations lead to high proliferation of malignant cells enabling sustained tumour growth. Understanding the precise mechanisms underlying these pathways is necessary to delineate efficient therapeutical approaches for each specific tumour type. We particularly focused on the Mitogen-Activated Protein Kinase (MAPK) signalling network, whose involvement in cancer is well established, although the precise conditions leading to its positive or negative influence on cell proliferation are still poorly understood. We tackled this problem by first collecting sparse published biological information into a comprehensive map describing the MAPK network in terms of stylised chemical reactions. This information source was then used to build a dynamical Boolean model recapitulating network responses to characteristic stimuli observed in selected bladder cancers. Systematic model simulations further allowed us to link specific network components and interactions with proliferative/anti-proliferative cell responses.

Rab27 effectors, pleiotropic regulators in secretory pathways

Rab27, a member of the small GTPase Rab family, is widely conserved in metazoan, and two Rab27 isoforms, Rab27A and Rab27B, are present in vertebrates. Rab27A was the first Rab protein whose dysfunction was found to cause a human hereditary disease, type 2 Griscelli syndrome, which is characterized by silvery hair and immunodeficiency. The discovery in the 21st century of three distinct types of mammalian Rab27A effectors [synaptotagmin-like protein (Slp), Slp homologue lacking C2 domains (Slac2), and Munc13-4] that specifically bind active Rab27A has greatly accelerated our understanding not only of the molecular mechanisms of Rab27A-mediated membrane traffic (e.g. melanosome transport and regulated secretion) but of the symptoms of Griscelli syndrome patients at the molecular level. Because Rab27B is widely expressed in various tissues together with Rab27A and has been found to have the ability to bind all of the Rab27A effectors that have been tested, Rab27A and Rab27B were initially thought to function redundantly by sharing common Rab27 effectors. However, recent evidence has indicated that by interacting with different Rab27 effectors Rab27A and Rab27B play different roles in special types of secretion (e.g. exosome secretion and mast cell secretion) even within the same cell type. In this review article, I describe the current state of our understanding of the functions of Rab27 effectors in secretory pathways.

Rab27 GTPases distribute extracellular nanomaps for invasive growth and metastasis: implications for prognosis and treatment

The Rab27 family of small GTPases regulates exocytosis of distinct vesicle types including multivesicular endosomes, which results in the release of exosomes. Exosomes are nanometer-sized membrane vesicles that enclose soluble factors such as proteins and nucleic acids within a lipid bilayer and can travel toward distant tissues to influence multiple aspects of cell behavior. In our view that tumors are endocrine organs producing exosomes, Rab27 GTPases and their effector proteins are critical determinants for invasive growth and metastasis. Rab27 proteins and their effectors may serve as prognostic biomarkers or as targets for patient-tailored therapy.

The Rab family of proteins: 25 years on

Intracellular membrane trafficking requires the complex interplay of several classes of trafficking proteins. Rab proteins, the largest subfamily of the Ras superfamily of small G-proteins, are central regulators of all aspects of intracellular trafficking processes including vesicle budding and uncoating, motility, tethering and fusion. In the present paper, we discuss the discovery, evolution and characterization of the Rab GTPase family. We examine their basic functional roles, their important structural features and the regulatory proteins which mediate Rab function. We speculate on outstanding issues in the field, such as the mechanisms of Rab membrane association and the co-ordinated interplay between distinct Rab proteins. Finally, we summarize the data implicating Rab proteins in an ever increasing number of diseases.

Rab27a and melanosomes: a model to investigate the membrane targeting of Rabs

Rab proteins constitute the largest family within the Ras superfamily of small GTPases (>60 in mammals) and are essential regulators of transport between intracellular organelles. Key to this activity is their targeting to specific compartments within the cell. However, although great strides have been made over the last 25 years in assigning functions to individual Rabs and identifying their downstream effectors, the mechanism(s) regulating their targeting to specific subcellular membranes remains less well understood. In the present paper, we review the evidence supporting the proposed mechanisms of Rab targeting and highlight insights into this process provided by studies of Rab27a.

Novel functions for Rab GTPases in multiple aspects of tumour progression

Rab GTPases are master regulators of intracellular trafficking and, in recent years, their role in the control of different aspects of tumour progression has emerged. In the present review, we show that Rab GTPases are disregulated in many cancers and have central roles in tumour cell migration, invasion, proliferation, communication with stromal cells and the development of drug resistance. As a consequence, Rab proteins may be novel potential candidates for the development of anticancer drugs and, in this context, the preliminary results obtained with an inhibitor of Rab function are also discussed.

Gene expression signatures differentiate uterine endometrial stromal sarcoma from leiomyosarcoma

OBJECTIVE

Endometrial stromal sarcoma (ESS) and leiomyosarcoma (LMS) are the two most common uterine sarcomas, but both are rare tumors. The aim of the present study was to compare the global gene expression patterns of ESS and LMS.

METHODS

Gene expression profiles of 7 ESS and 13 LMS were analyzed using the HumanRef-8 BeadChip from Illumina. Differentially expressed candidate genes were validated using quantitative real-time PCR and immunohistochemistry.

RESULTS

Unsupervised hierarchical clustering using all 54,675 genes in the array separated ESS from LMS samples. We identified 549 unique probes that were significantly differentially expressed in the two malignancies by greater than 2-fold with 1% FDR cutoff using one-way ANOVA with Benjamini-Hochberg correction, of which 336 and 213 were overexpressed in ESS and LMS, respectively. Genes overexpressed in ESS included SLC7A10, EFNB3, CCND2, ECEL1, ITM2A, NPW, PLAG1 and GCGR. Genes overexpressed in LMS included CDKN2A, FABP3, TAGLN, JPH2, GEM, NAV2 and RAB23. The top 100 genes overexpressed in LMS included those coding for myosin light chain and caldesmon, but not the genes coding for desmin or actin. CD10 was not overexpressed in ESS. Results for selected genes were validated by quantitative real-time PCR and immunohistochemistry.

CONCLUSIONS

We present the first study in which gene expression profiling was shown to distinguish between ESS and LMS. The molecular signatures unique to each of these malignancies may aid in expanding the diagnostic battery for their differentiation, and may provide a molecular basis for prognostic studies and therapeutic target discovery.