RAB25

Gene Summary

Gene:RAB25; RAB25, member RAS oncogene family
Aliases: CATX-8, RAB11C
Location:1q22
Summary:RAB proteins, such as RAB25, are members of the RAS superfamily of small GTPases that are involved in membrane trafficking. Members of the RAB11 subfamily, including RAB25, control the return of internalized membrane-associated moieties to the cell surface (Caswell et al., 2007 [PubMed 17925226]).[supplied by OMIM, Aug 2009]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:ras-related protein Rab-25
HPRD
Source:NCBIAccessed: 25 June, 2015

Ontology:

What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 25 June 2015 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 25 June, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: RAB25 (cancer-related)

Li Y, Jia Q, Zhang Q, Wan Y
Rab25 upregulation correlates with the proliferation, migration, and invasion of renal cell carcinoma.
Biochem Biophys Res Commun. 2015; 458(4):745-50 [PubMed] Related Publications
Renal cell carcinoma (RCC) is a common urological cancer with a poor prognosis. A recent cohort study revealed that the median survival of RCC patients was only 1.5 years and that <10% of the patients in the study survived up to 5 years. In tumor development, Rab GTPase are known to play potential roles such as regulation of cell proliferation, migration, invasion, communication, and drug resistance in multiple tumors. However, the correlation between Rabs expression and the occurrence, development, and metastasis of RCC remains unclear. In this study, we analyzed the transcriptional levels of 52 Rab GTPases in RCC patients. Our results showed that high levels of Rab25 expression were significantly correlated with RCC invasion classification (P < 0.01), lymph-node metastasis (P < 0.001), and pathological stage (P < 0.01). Conversely, in 786-O and A-498 cells, knocking down Rab25 protein expression inhibited cell proliferation, migration, and invasion. Our results also demonstrated that Rab25 is a target gene of let-7d, and further suggested that Rab25 upregulation in RCC is due to diminished expression of let-7d. These findings indicate that Rab25 might be a novel candidate molecule involved in RCC development, thus identifying a potential biological therapeutic target for RCC.

Davidson B, Holth A, Hellesylt E, et al.
The clinical role of epithelial-mesenchymal transition and stem cell markers in advanced-stage ovarian serous carcinoma effusions.
Hum Pathol. 2015; 46(1):1-8 [PubMed] Related Publications
We recently identified gene signatures that allow classification of ovarian carcinoma into 5 distinct clinically relevant groups. In the present study, we investigated the clinical role of 10 protein products of the discriminating genes, with focus on epithelial-mesenchymal transition and stem cell markers. Expression of E-cadherin, N-cadherin, P-cadherin, Zeb1, HMGA2, Rab25, CD24, NCAM (CD56), Sox11, and vimentin was assessed in 100 advanced-stage (International Federation of Gynecology and Obstetrics stages III-IV) serous ovarian carcinoma effusions using immunohistochemistry. Results were analyzed for association with clinicopathological parameters, including chemotherapy response, and survival. All 10 proteins were frequently expressed in carcinoma cells. HMGA2 expression was related to older age (P = .015). HMGA2 and NCAM expression was related to stage III disease (P = .011 and P = .023, respectively), and NCAM was overexpressed in peritoneal compared with pleural effusions (P = .001). Vimentin and Zeb1 expression was significantly related to poor chemotherapy response at diagnosis (P = .005 and P = .017, respectively). The associations between NCAM and peritoneal localization and of vimentin and poor chemoresponse were retained after Bonferroni correction. NCAM expression was associated with a trend for shorter overall survival in univariate survival analysis (P = .187), but emerged as an independent prognosticator in Cox multivariate analysis (P = .042). This study identifies vimentin and Zeb1 as markers of poor chemoresponse in metastatic serous ovarian carcinoma effusions and suggests NCAM as potential prognostic marker in metastatic disease. The generally limited prognostic role of the studied markers emphasizes the difficulty in applying data obtained in studies of primary ovarian carcinomas to analyses of ovarian carcinoma effusions, reflecting the unique biology of the latter.

Jo U, Park KH, Whang YM, et al.
EGFR endocytosis is a novel therapeutic target in lung cancer with wild-type EGFR.
Oncotarget. 2014; 5(5):1265-78 [PubMed] Free Access to Full Article Related Publications
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.

Zhang J, Wei J, Lu J, et al.
Overexpression of Rab25 contributes to metastasis of bladder cancer through induction of epithelial-mesenchymal transition and activation of Akt/GSK-3β/Snail signaling.
Carcinogenesis. 2013; 34(10):2401-8 [PubMed] Related Publications
Rab25, an epithelial-specific member of the Rab family of small guanosine triphosphatases, is associated with several human cancers. The goal of this study was to determine its function in bladder cancer (BC). We examined the Rab25 expression pattern in two different cohorts of BC patients treated with radical cystectomy by quantitative PCR, western blotting and immunohistochemical staining. A series of in vitro and in vivo assays were performed to elucidate the function of Rab25 in BC and its underlying mechanisms. Rab25 expression was significantly elevated at both the messenger RNA and protein levels in BCs compared with normal bladder tissues. High Rab25 expression was closely associated with lymph node (LN) metastasis and was an independent predictor for poor disease-free survival in BC patients. Downregulation of Rab25 in BC cells markedly inhibited invasive motility in vitro and metastatic potential in vivo. In addition, downregulation of Rab25 in BC EJ and T24 cells increased the expression levels of epithelial markers (E-cadherin and α-catenin) and decreased the levels of mechamechy markers (vimentin and fibronectin). Simultaneously, downregulation of Rab25 in EJ and T24 cells resulted in the inactivation of downstream phosphorylated protein kinase B (p-Akt), phosphorylated glycogen synthase kinase-β (p-GSK-3β) and snail signaling. This study demonstrates that Rab25 can promote BC metastasis through induction of epithelial-mesenchymal transition process and activation of Akt/GSK-3β/Snail signaling pathway; Rab25 expression level can predict LN metastasis and inferior clinical outcome in BC patients.

Pénzváltó Z, Tegze B, Szász AM, et al.
Identifying resistance mechanisms against five tyrosine kinase inhibitors targeting the ERBB/RAS pathway in 45 cancer cell lines.
PLoS One. 2013; 8(3):e59503 [PubMed] Free Access to Full Article Related Publications
Because of the low overall response rates of 10-47% to targeted cancer therapeutics, there is an increasing need for predictive biomarkers. We aimed to identify genes predicting response to five already approved tyrosine kinase inhibitors. We tested 45 cancer cell lines for sensitivity to sunitinib, erlotinib, lapatinib, sorafenib and gefitinib at the clinically administered doses. A resistance matrix was determined, and gene expression profiles of the subsets of resistant vs. sensitive cell lines were compared. Triplicate gene expression signatures were obtained from the caArray project. Significance analysis of microarrays and rank products were applied for feature selection. Ninety-five genes were also measured by RT-PCR. In case of four sunitinib resistance associated genes, the results were validated in clinical samples by immunohistochemistry. A list of 63 top genes associated with resistance against the five tyrosine kinase inhibitors was identified. Quantitative RT-PCR analysis confirmed 45 of 63 genes identified by microarray analysis. Only two genes (ANXA3 and RAB25) were related to sensitivity against more than three inhibitors. The immunohistochemical analysis of sunitinib-treated metastatic renal cell carcinomas confirmed the correlation between RAB17, LGALS8, and EPCAM and overall survival. In summary, we determined predictive biomarkers for five tyrosine kinase inhibitors, and validated sunitinib resistance biomarkers by immunohistochemistry in an independent patient cohort.

Krishnan M, Lapierre LA, Knowles BC, Goldenring JR
Rab25 regulates integrin expression in polarized colonic epithelial cells.
Mol Biol Cell. 2013; 24(6):818-31 [PubMed] Free Access to Full Article Related Publications
Rab25 is a tumor suppressor for colon cancer in humans and mice. To identify elements of intestinal polarity regulated by Rab25, we developed Caco2-BBE cell lines stably expressing short hairpin RNA for Rab25 and lines rescuing Rab25 knockdown with reexpression of rabbit Rab25. Rab25 knockdown decreased α2-, α5-, and β1-integrin expression. We observed colocalization and direct association of Rab25 with α5β1-integrins. Rab25 knockdown also up-regulated claudin-1 expression, increased transepithelial resistance, and increased invasive behavior. Rab25-knockdown cells showed disorganized brush border microvilli with decreases in villin expression. All of these changes were reversed by reintroduction of rabbit Rab25. Rab25 knockdown altered the expression of 29 gene transcripts, including the loss of α5-integrin transcripts. Rab25 loss decreased expression of one transcription factor, ETV4, and overexpression of ETV4 in Rab25-knockdown cells reversed losses of α5β1-integrin. The results suggest that Rab25 controls intestinal cell polarity through the regulation of gene expression.

Amornphimoltham P, Rechache K, Thompson J, et al.
Rab25 regulates invasion and metastasis in head and neck cancer.
Clin Cancer Res. 2013; 19(6):1375-88 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Head and neck squamous cell carcinoma (HNSCC) is one of the 10 most common cancers with a 50% five-year survival rate, which has remained unchanged for the past three decades. One of the major reasons for the aggressiveness of this cancer is that HNSCCs readily metastasize to cervical lymph nodes that are abundant in the head and neck region. Hence, discovering new molecules controlling the metastatic process as well as understanding their regulation at the molecular level are essential for effective therapeutic strategies.
EXPERIMENTAL DESIGN: Rab25 expression level was analyzed in HNSCC tissue microarray. We used a combination of intravital microscopy in live animals and immunofluorescence in an in vitro invasion assay to study the role of Rab25 in tumor cell migration and invasion.
RESULTS: In this study, we identified the small GTPase Rab25 as a key regulator of HNSCC metastasis. We observed that Rab25 is downregulated in HNSCC patients. Next, we determined that reexpression of Rab25 in a metastatic cell line is sufficient to block invasion in a three-dimensional collagen matrix and metastasis to cervical lymph nodes in a mouse model for oral cancer. Specifically, Rab25 affects the organization of F-actin at the cell surface, rather than cell proliferation, apoptosis, or tumor angiogenesis.
CONCLUSION: These findings suggest that Rab25 plays an important role in tumor migration and metastasis, and that understanding its function may lead to the development of new strategies to prevent metastasis in oral cancer patients.

Mitra S, Cheng KW, Mills GB
Rab25 in cancer: a brief update.
Biochem Soc Trans. 2012; 40(6):1404-8 [PubMed] Free Access to Full Article Related Publications
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.

Tringali C, Lupo B, Silvestri I, et al.
The plasma membrane sialidase NEU3 regulates the malignancy of renal carcinoma cells by controlling β1 integrin internalization and recycling.
J Biol Chem. 2012; 287(51):42835-45 [PubMed] Free Access to Full Article Related Publications
The human plasma membrane sialidase NEU3 is a key enzyme in the catabolism of membrane gangliosides, is crucial in the regulation of cell surface processes, and has been demonstrated to be significantly up-regulated in renal cell carcinomas (RCCs). In this report, we show that NEU3 regulates β1 integrin trafficking in RCC cells by controlling β1 integrin recycling to the plasma membrane and controlling activation of the epidermal growth factor receptor (EGFR) and focal adhesion kinase (FAK)/protein kinase B (AKT) signaling. NEU3 silencing in RCC cells increased the membrane ganglioside content, in particular the GD1a content, and changed the expression of key regulators of the integrin recycling pathway. In addition, NEU3 silencing up-regulated the Ras-related protein RAB25, which directs internalized integrins to lysosomes, and down-regulated the chloride intracellular channel protein 3 (CLIC3), which induces the recycling of internalized integrins to the plasma membrane. In this manner, NEU3 silencing enhanced the caveolar endocytosis of β1 integrin, blocked its recycling and reduced its levels at the plasma membrane, and, consequently, inhibited EGFR and FAK/AKT. These events had the following effects on the behavior of RCC cells: they (a) decreased drug resistance mediated by the block of autophagy and the induction of apoptosis; (b) decreased metastatic potential mediated by down-regulation of the metalloproteinases MMP1 and MMP7; and (c) decreased adhesion to collagen and fibronectin. Therefore, our data identify NEU3 as a key regulator of the β1 integrin-recycling pathway and FAK/AKT signaling and demonstrate its crucial role in RCC malignancy.

Gonzalez-Angulo AM, Liu S, Chen H, et al.
Functional proteomics characterization of residual breast cancer after neoadjuvant systemic chemotherapy.
Ann Oncol. 2013; 24(4):909-16 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The purpose of this study was to determine the functional proteomic characteristics of residual breast cancer and hormone receptor (HR)-positive breast cancer after neoadjuvant systemic chemotherapy, and their relationship with patient outcomes.
METHODS: Reverse phase protein arrays of 76 proteins were carried out. A boosting approach in conjunction with a Cox proportional hazard model defined relapse predictors. A risk score (RS) was calculated with the sum of the coefficients from the final model. Survival outcomes and associations of the RS with relapse were estimated. An independent test set was used to validate the results.
RESULTS: Test (n = 99) and validation sets (n = 79) were comparable. CoxBoost revealed a three-biomarker (CHK1pS345, Caveolin1, and RAB25) and a two-biomarker (CD31 and Cyclin E1) model that correlated with recurrence-free survival (RFS) in all residual breast cancers and in HR-positive disease, respectively. Unsupervised clustering split patients into high- and low risk of relapse groups with different 3-year RFS (P ≤ 0.001 both). RS was a substantial predictor of RFS (P = 0.0008 and 0.0083) after adjustment for other substantial characteristics. Similar results were found in validation sets.
CONCLUSIONS: We found models that independently predicted RFS in all residual breast cancer and in residual HR-positive disease that may represent potential targets of therapy in this resistant disease.

Tong M, Chan KW, Bao JY, et al.
Rab25 is a tumor suppressor gene with antiangiogenic and anti-invasive activities in esophageal squamous cell carcinoma.
Cancer Res. 2012; 72(22):6024-35 [PubMed] Related Publications
Esophageal squamous cell carcinoma (ESCC), the major histologic subtype of esophageal cancer, is a devastating disease characterized by distinctly high incidences and mortality rates. However, there remains limited understanding of molecular events leading to development and progression of the disease, which are of paramount importance to defining biomarkers for diagnosis, prognosis, and personalized treatment. By high-throughout transcriptome sequence profiling of nontumor and ESCC clinical samples, we identified a subset of significantly differentially expressed genes involved in integrin signaling. The Rab25 gene implicated in endocytic recycling of integrins was the only gene in this group significantly downregulated, and its downregulation was confirmed as a frequent event in a second larger cohort of ESCC tumor specimens by quantitative real-time PCR and immunohistochemical analyses. Reduced expression of Rab25 correlated with decreased overall survival and was also documented in ESCC cell lines compared with pooled normal tissues. Demethylation treatment and bisulfite genomic sequencing analyses revealed that downregulation of Rab25 expression in both ESCC cell lines and clinical samples was associated with promoter hypermethylation. Functional studies using lentiviral-based overexpression and suppression systems lent direct support of Rab25 to function as an important tumor suppressor with both anti-invasive and -angiogenic abilities, through a deregulated FAK-Raf-MEK1/2-ERK signaling pathway. Further characterization of Rab25 may provide a prognostic biomarker for ESCC outcome prediction and a novel therapeutic target in ESCC treatment.

No JH, Kim K, Park KH, Kim YB
Cell-free DNA level as a prognostic biomarker for epithelial ovarian cancer.
Anticancer Res. 2012; 32(8):3467-71 [PubMed] Related Publications
BACKGROUND: The use of cell-free DNA (cfDNA) as a non-invasive biomarker has been evaluated in many types of cancer. This study investigated the prognostic significance of cfDNA level for ovarian cancer.
MATERIALS AND METHODS: Preoperative sera of 36 patients with ovarian cancer and of 16 with benign tumors were analyzed using commercially available copy number assay kits to measure the cfDNA level of genes including beta-2-microglobulin (B2M), member RAS oncogene family (RAB25), claudin 4 (CLDN4) and ATP-binding cassette subfamily F member 2 (ABCF2). Cox regression analysis was used to calculate hazard ratios (HR) and 95% confidence intervals (CI).
RESULTS: cfDNA level of these genes had no association with other prognostic factors of ovarian cancer. In particular, in patients with advanced stage disease, a low RAB25 level was an independent prognostic factor for disease-free survival (HR=18.2, 95% CI=2.0-170.0) and overall survival (HR=33.6, 95% CI=1.8-634.8).
CONCLUSION: Our findings suggest that the preoperative serum cfDNA level of RAB25 could be a useful biomarker predicting survival outcomes in patients with advanced ovarian cancer.

Leth-Larsen R, Terp MG, Christensen AG, et al.
Functional heterogeneity within the CD44 high human breast cancer stem cell-like compartment reveals a gene signature predictive of distant metastasis.
Mol Med. 2012; 18:1109-21 [PubMed] Free Access to Full Article Related Publications
The CD44(hi) compartment in human breast cancer is enriched in tumor-initiating cells; however, the functional heterogeneity within this subpopulation remains poorly defined. We used a triple-negative breast cancer cell line with a known bilineage phenotype to isolate and clone CD44(hi) single cells that exhibited mesenchymal/basal B and luminal/basal A features, respectively. Herein, we demonstrate in this and other triple-negative breast cancer cell lines that, rather than CD44(hi)/CD24(-) mesenchymal-like basal B cells, the CD44(hi)/CD24(lo) epithelioid basal A cells retained classic cancer stem cell features, such as tumor-initiating capacity in vivo, mammosphere formation and resistance to standard chemotherapy. These results complement previous findings using oncogene-transformed normal mammary cells showing that only cell clones with a mesenchymal phenotype exhibit cancer stem cell features. Further, we performed comparative quantitative proteomic and gene array analyses of these cells and identified potential novel markers of breast cancer cells with tumor-initiating features, such as lipolysis-stimulated lipoprotein receptor (LSR), RAB25, S100A14 and mucin 1 (MUC1), as well as a novel 31-gene signature capable of predicting distant metastasis in cohorts of estrogen receptor-negative human breast cancers. These findings strongly favor functional heterogeneity in the breast cancer cell compartment and hold promise for further refinements of prognostic marker profiling. Our work confirms that, in addition to cancer stem cells with mesenchymal-like morphology, those tumor-initiating cells with epithelial-like morphology should also be the focus of drug development.

Yin YX, Shen F, Pei H, et al.
Increased expression of Rab25 in breast cancer correlates with lymphatic metastasis.
Tumour Biol. 2012; 33(5):1581-7 [PubMed] Related Publications
Breast cancer is the most common cancer in women worldwide. Studies have suggested that Ras-related protein 25 (Rab25), a member of Rab small GTPase family, is involved in the pathogenesis of breast cancer. In this study, we investigated whether the expression of Rab25 correlated with lymphatic metastasis in breast cancer and whether the expression of Rab25 was positively correlated with oestrogen receptor (ER) and progesterone receptor (PR) expression in breast cancer. Breast cancer tissues from 42 invasive ductal breast cancer patients with or without lymphatic metastasis were collected and the levels of Rab25 mRNA and protein measured by quantitative real-time PCR and immunohistochemistry, respectively. The mRNA level of Rab25 was significantly increased in invasive ductal breast cancer with lymphatic metastasis compared to that in invasive ductal breast cancer without lymphatic metastasis. Immunohistochemical analysis demonstrated that Rab25 and vascular endothelial growth factor (VEGF) were highly expressed in invasive ductal breast cancer with lymphatic metastasis regardless of whether the cancer is ER and PR positive or negative. Higher expression of Rab25 positively correlated with VEGF expression. However, the expressions of Rab25 in ER and PR-positive cancers were much higher than ER and PR-negative cancers regardless of whether lymphatic metastasis occurred. These data suggest that higher level of Rab25 was associated with lymphatic metastasis, specifically in ER and PR-positive breast cancer. The better understanding of the mechanism of Rab25 may provide a basis for the development of a novel therapeutic target in breast cancer.

Brusegard K, Stavnes HT, Nymoen DA, et al.
Rab25 is overexpressed in Müllerian serous carcinoma compared to malignant mesothelioma.
Virchows Arch. 2012; 460(2):193-202 [PubMed] Related Publications
Rab25, an epithelial-specific member of the Rab family of small GTPases, was previously shown to be overexpressed in ovarian/primary peritoneal serous carcinoma compared to malignant mesothelioma using gene expression arrays. The objective of this study was to validate this finding at the mRNA and protein level. Quantitative PCR analysis of 112 Müllerian serous carcinomas (84 effusions, 28 primary ovarian carcinomas) and 22 malignant mesotheliomas (19 effusions, 3 solid specimens) showed significantly higher RAB25 mRNA expression in the former tumor (p < 0.001). Immunohistochemical analysis of Rab25 protein expression in 245 effusions showed significantly higher expression of this protein in Müllerian serous carcinoma compared to malignant mesothelioma (189/209 vs. 12/36 positive tumors, respectively; p < 0.001). Immunostaining of 101 patient-matched solid Müllerian carcinoma specimens (34 primary carcinomas, 67 metastases) showed expression levels comparable to effusions (94/101 positive specimens; p > 0.05). Rab25 mRNA and protein expression levels in Müllerian carcinoma effusions did not correlate with overall or progression-free survival. Our data confirm that Rab25 effectively differentiates Müllerian carcinomas from malignant mesothelioma at the mRNA and protein level, suggesting a role in the diagnostic work-up of serosal cancers.

Zhang G, Shang B, Yang P, et al.
Induced pluripotent stem cell consensus genes: implication for the risk of tumorigenesis and cancers in induced pluripotent stem cell therapy.
Stem Cells Dev. 2012; 21(6):955-64 [PubMed] Related Publications
Induced pluripotent stem cells (iPSCs) have recently boomed enthusiasm in stem cell therapy, whereas high potential tumorigenesis of iPSCs has become the biggest obstacle for clinic application and the tumorigenic genes in iPSCs have not been well documented. In this investigation, using tools of bioinformatics, we analyzed the all available datasets regarded to iPSCs from 11 differentiated cell lines and revealed 593 iPSC consensus genes. Notably, of the 593 genes, 209 were expressed in human tumor cell lines and cancer tissues, and some of them were expressed in the iPSC-differentiated hepatocytes; remarkably, 5 oncogenes were overexpressed in the iPSCs and an oncogene RAB25 in the iPSC-differentiated cells, suggesting that these iPSC consensus genes are implicated with the risk of tumorigenesis and cancers. This investigation provides useful information for designing new strategies and methods to curtail the expression of oncogenic genes in iPSCs and produce safe iPSC derivatives for stem cell therapy.

Wrzeszczynski KO, Varadan V, Byrnes J, et al.
Identification of tumor suppressors and oncogenes from genomic and epigenetic features in ovarian cancer.
PLoS One. 2011; 6(12):e28503 [PubMed] Free Access to Full Article Related Publications
The identification of genetic and epigenetic alterations from primary tumor cells has become a common method to identify genes critical to the development and progression of cancer. We seek to identify those genetic and epigenetic aberrations that have the most impact on gene function within the tumor. First, we perform a bioinformatic analysis of copy number variation (CNV) and DNA methylation covering the genetic landscape of ovarian cancer tumor cells. We separately examined CNV and DNA methylation for 42 primary serous ovarian cancer samples using MOMA-ROMA assays and 379 tumor samples analyzed by The Cancer Genome Atlas. We have identified 346 genes with significant deletions or amplifications among the tumor samples. Utilizing associated gene expression data we predict 156 genes with altered copy number and correlated changes in expression. Among these genes CCNE1, POP4, UQCRB, PHF20L1 and C19orf2 were identified within both data sets. We were specifically interested in copy number variation as our base genomic property in the prediction of tumor suppressors and oncogenes in the altered ovarian tumor. We therefore identify changes in DNA methylation and expression for all amplified and deleted genes. We statistically define tumor suppressor and oncogenic features for these modalities and perform a correlation analysis with expression. We predicted 611 potential oncogenes and tumor suppressors candidates by integrating these data types. Genes with a strong correlation for methylation dependent expression changes exhibited at varying copy number aberrations include CDCA8, ATAD2, CDKN2A, RAB25, AURKA, BOP1 and EIF2C3. We provide copy number variation and DNA methylation analysis for over 11,500 individual genes covering the genetic landscape of ovarian cancer tumors. We show the extent of genomic and epigenetic alterations for known tumor suppressors and oncogenes and also use these defined features to identify potential ovarian cancer gene candidates.

Vuoriluoto K, Haugen H, Kiviluoto S, et al.
Vimentin regulates EMT induction by Slug and oncogenic H-Ras and migration by governing Axl expression in breast cancer.
Oncogene. 2011; 30(12):1436-48 [PubMed] Related Publications
Epithelial-to-mesenchymal transition (EMT) is a critical event in the progression toward cancer metastasis. The intermediate filament protein vimentin is an important marker of EMT and a requisite regulator of mesenchymal cell migration. However, it is not known how vimentin functionally contributes to cancer cell invasion. Here, we report that ectopic expression of oncogenic H-Ras-V12G and Slug induces vimentin expression and migration in pre-malignant breast epithelial cells. Conversely, vimentin expression is necessary for Slug- or H-Ras-V12G-induced EMT-associated migration. Furthermore, silencing of vimentin in breast epithelial cells results in specific changes in invasiveness-related gene expression including upregulation of RAB25 (small GTPase Rab25) and downregulation of AXL (receptor tyrosine kinase Axl), PLAU (plasminogen activator, urokinase) and ITGB4 (integrin β4-subunit). Importantly, gene expression profiling analyses reveal that vimentin expression correlates positively/negatively with these genes also in multiple breast cancer cell lines and breast cancer patient samples. Focusing on the tyrosine kinase Axl, we show that induction of vimentin by EMT is associated with upregulation of Axl expression and that Axl enhances the migratory activity of pre-malignant breast epithelial cells. Using null and knock-down cells and overexpression models, we also show that regulation of breast cancer cell migration in two- and three-dimensional matrices by vimentin is Axl- dependent and that Axl functionally contributes to lung extravasation of breast cancer cells in mice. In conclusion, our data show that vimentin functionally contributes to EMT and is required for induction of Axl expression. Moreover, these results provide a molecular explanation for vimentin-dependent cancer cell migration during EMT by identifying Axl as a key proximal component in this process.

Nam KT, Lee HJ, Smith JJ, et al.
Loss of Rab25 promotes the development of intestinal neoplasia in mice and is associated with human colorectal adenocarcinomas.
J Clin Invest. 2010; 120(3):840-9 [PubMed] Free Access to Full Article Related Publications
Transformation of epithelial cells is associated with loss of cell polarity, which includes alterations in cell morphology as well as changes in the complement of plasma membrane proteins. Rab proteins regulate polarized trafficking to the cell membrane and therefore represent potential regulators of this neoplastic transition. Here we have demonstrated a tumor suppressor function for Rab25 in intestinal neoplasia in both mice and humans. Human colorectal adenocarcinomas exhibited reductions in Rab25 expression independent of stage, with lower Rab25 expression levels correlating with substantially shorter patient survival. In wild-type mice, Rab25 was strongly expressed in cells luminal to the proliferating cells of intestinal crypts. While Rab25-deficient mice did not exhibit gross pathology, ApcMin/+ mice crossed onto a Rab25-deficient background showed a 4-fold increase in intestinal polyps and a 2-fold increase in colonic tumors compared with parental ApcMin/+ mice. Rab25-deficient mice had decreased beta1 integrin staining in the lateral membranes of villus cells, and this pattern was accentuated in Rab25-deficient mice crossed onto the ApcMin/+ background. Additionally, Smad3+/- mice crossed onto a Rab25-deficient background demonstrated a marked increase in colonic tumor formation. Taken together, these results suggest that Rab25 may function as a tumor suppressor in intestinal epithelial cells through regulation of protein trafficking to the cell surface.

Cheng JM, Volk L, Janaki DK, et al.
Tumor suppressor function of Rab25 in triple-negative breast cancer.
Int J Cancer. 2010; 126(12):2799-812 [PubMed] Related Publications
Rab proteins are a group of ubiquitously expressed proteins that are responsible for intracellular transport of vesicles. Recent evidence has shown that certain Rab proteins are involved in the pathogenesis of cancer. We have recently shown that Rab25 is lost in a large fraction of breast cancer samples, particularly those derived from hormonally insensitive tumors. We have further investigated the role of Rab25 by re-expressing Rab25 in tumorigenic cell lines and measuring the impact on tumor formation as well as on various molecular pathways through PCR array analysis. In vivo tumor growth of cell lines with re-expressed Rab25 was markedly suppressed. Our data suggest that Rab25 acts through multiple pathways to enhance apoptosis and to suppress angiogenesis and invasion by modulating VEGF-A and VEGFR-1 expression. These findings suggest that Rab25 represents a novel class of cellular modulators that can influence both tumor initiation and the progression of the established tumors, thus ultimately affecting the biology of the malignant disease.

Sheach LA, Adeney EM, Kucukmetin A, et al.
Androgen-related expression of G-proteins in ovarian cancer.
Br J Cancer. 2009; 101(3):498-503 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Epidemiological and in vitro data implicate androgens in the aetiology of ovarian cancer, but the mechanisms by which this is mediated are unclear. In this study, we wished to examine the effects of androgens on gene expression in ovarian cancer.
METHODS: The expression of androgen receptor (AR) in OVCAR3 and OSEC2 cells was confirmed using immunoblotting and response to androgens was measured using flow cytometric assessment of S-phase fraction. The differential gene expression between androgen stimulated and unstimulated OVCAR3 ovarian cancer cells was examined with a cDNA microarray. The upregulation of a subset of these genes was then confirmed with reverse transcriptase PCR in both OVCAR3 and OSEC2, an ovarian epithelial cell line. Finally, the clinical significance of this upregulation was investigated by examining the expression of Rab25 and Rab35, two G-protein-related molecules in an ovarian cancer tissue microarray (TMA).
RESULTS: OVCAR3 and OSEC2 cells were shown to express the AR and showed an increase in S-phase fraction in response to androgen treatment. Treatment of OVCAR3 cells with androgen resulted in a significant upregulation of 121 genes. These findings were confirmed for a subset of seven monomeric G-protein-related genes in both OVCAR3 and OSEC2 cells. After staining for Rab25 and Rab35, the majority of TMA sections examined showed expression for Rab25 (92%) and Rab35 (95%). The expression of Rab25 correlated with histological grade, and expression was higher in endometrioid (median histoscore 10.5) than serous (7.5) or mucinous (5.3) tumours. The expression of Rab25 correlated positively with AR expression supporting its role as an androgen responsive gene in ovarian cancer.
CONCLUSIONS: These results suggest that androgens can effect expression of the oncogenic GTPases in ovarian cancer. We propose that the androgen responsive Rab35 may have clinical importance as a biomarker of AR function.

Zhang J, Liu X, Datta A, et al.
RCP is a human breast cancer-promoting gene with Ras-activating function.
J Clin Invest. 2009; 119(8):2171-83 [PubMed] Free Access to Full Article Related Publications
Aggressive forms of cancer are often defined by recurrent chromosomal alterations, yet in most cases, the causal or contributing genetic components remain poorly understood. Here, we utilized microarray informatics to identify candidate oncogenes potentially contributing to aggressive breast cancer behavior. We identified the Rab-coupling protein RCP (also known as RAB11FIP1), which is located at a chromosomal region frequently amplified in breast cancer (8p11-12) as a potential candidate. Overexpression of RCP in MCF10A normal human mammary epithelial cells resulted in acquisition of tumorigenic properties such as loss of contact inhibition, growth-factor independence, and anchorage-independent growth. Conversely, knockdown of RCP in human breast cancer cell lines inhibited colony formation, invasion, and migration in vitro and markedly reduced tumor formation and metastasis in mouse xenograft models. Overexpression of RCP enhanced ERK phosphorylation and increased Ras activation in vitro. As these results indicate that RCP is a multifunctional gene frequently amplified in breast cancer that encodes a protein with Ras-activating function, we suggest it has potential importance as a therapeutic target. Furthermore, these studies provide new insight into the emerging role of the Rab family of small G proteins and their interacting partners in carcinogenesis.

Mills GB, Jurisica I, Yarden Y, Norman JC
Genomic amplicons target vesicle recycling in breast cancer.
J Clin Invest. 2009; 119(8):2123-7 [PubMed] Free Access to Full Article Related Publications
Aberrant endocytosis, vesicle targeting, and receptor recycling represent emerging hallmarks of cancer. In this issue of the JCI, Zhang and colleagues demonstrate that RAB-coupling protein (RCP; also known as RAB11FIP1) is a "driver" of the 8p11-12 amplicon in human breast cancer and mouse xenograft models of mammary carcinogenesis (see the related article beginning on page 2171). Their finding that RAB GTPase function enables genomic amplification to confer aggressiveness to mammary tumors adds significantly to the body of evidence supporting pivotal roles for receptor trafficking in the proliferation and metastasis of cancer.

Bigelow RL, Williams BJ, Carroll JL, et al.
TIMP-1 overexpression promotes tumorigenesis of MDA-MB-231 breast cancer cells and alters expression of a subset of cancer promoting genes in vivo distinct from those observed in vitro.
Breast Cancer Res Treat. 2009; 117(1):31-44 [PubMed] Related Publications
TIMP-1 (Tissue inhibitor of matrix metalloproteinase-1) is typically associated with inhibition of matrix metalloproteinases (MMP) induced invasion. However, TIMP-1 is overexpressed in many malignancies and is associated with poor prognosis in breast cancer. The mechanisms by which TIMP-1 promotes tumorigenesis are unclear. Reduced levels of TIMP-1 mediated by shRNA in MDA-MB-231 breast cancer cells had no effect on cellular physiology in vitro or tumor growth in SCID mice compared to vector control MDA-MB-231 cells. However, overexpression of TIMP-1 in MDA-MB-231 cells resulted in inhibition of cell invasion and enhanced phosphorylation of p38 MAPK and AKT in vitro. Additionally, treatment of parental MDA-MB-231 cells with purified TIMP-1 protein led to activation of p38 MAPK and MKK 3/6. cDNA array analysis demonstrated that high expression of TIMP-1 in MDA-MB-231 cells resulted in alterations in expression of approximately 200 genes, 1.5 fold or greater compared to vector control cells (P < 0.1). Real-time RT-PCR confirmed changes in expression of several genes associated with cancer progression including DAPK1, FGFR4 and MAPK13. In vivo, high TIMP-1 expression induced tumor growth in SCID mice compared to vector control cells and increased tumor vessel density. Affymetrix array analysis of vector control and TIMP-1 MDA-MB-231 xenograft tumors revealed that TIMP-1 altered expression of approximately 600 genes in vivo, including MMP1, MMP13, S100A14, S100P, Rab25 and ID4. These combined observations suggest that the effects of TIMP-1 differ significantly in a 2-D environment compared to the 3-D environment and that TIMP-1 stimulates tumor growth.

Simmen FA, Su Y, Xiao R, et al.
The Krüppel-like factor 9 (KLF9) network in HEC-1-A endometrial carcinoma cells suggests the carcinogenic potential of dys-regulated KLF9 expression.
Reprod Biol Endocrinol. 2008; 6:41 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Krüppel-like factor 9 (KLF9) is a transcriptional regulator of uterine endometrial cell proliferation, adhesion and differentiation; processes essential for pregnancy success and which are subverted during tumorigenesis. The network of endometrial genes controlled by KLF9 is largely unknown. Over-expression of KLF9 in the human endometrial cancer cell line HEC-1-A alters cell morphology, proliferative indices, and differentiation, when compared to KLF9 under-expressing HEC-1-A cells. This cell line provides a unique model for identifying KLF9 downstream gene targets and signaling pathways.
METHODS: HEC-1-A sub-lines differing in relative levels of KLF9 were subjected to microarray analysis to identify differentially-regulated RNAs.
RESULTS: KLF9 under-expression induced twenty four genes. The KLF9-suppressed mRNAs encode protein participants in: aldehyde metabolism (AKR7A2, ALDH1A1); regulation of the actin cytoskeleton and cell motility (e.g., ANK3, ITGB8); cellular detoxification (SULT1A1, ABCC4); cellular signaling (e.g., ACBD3, FZD5, RAB25, CALB1); and transcriptional regulation (PAX2, STAT1). Sixty mRNAs were more abundant in KLF9 over-expressing sub-lines. The KLF9-induced mRNAs encode proteins which participate in: regulation and function of the actin cytoskeleton (COTL1, FSCN1, FXYD5, MYO10); cell adhesion, extracellular matrix and basement membrane formation (e.g., AMIGO2, COL4A1, COL4A2, LAMC2, NID2); transport (CLIC4); cellular signaling (e.g., BCAR3, MAPKAPK3); transcriptional regulation [e.g., KLF4, NR3C1 (glucocorticoid receptor), RXRalpha], growth factor/cytokine actions (SLPI, BDNF); and membrane-associated proteins and receptors (e.g., CXCR4, PTCH1). In addition, the abundance of mRNAs that encode hypothetical proteins (KLF9-inhibited: C12orf29 and C1orf186; KLF9-induced: C10orf38 and C9orf167) were altered by KLF9 expression. Human endometrial tumors of high tumor grade had decreased KLF9 mRNA abundance.
CONCLUSION: KLF9 influences the expression of uterine epithelial genes through mechanisms likely involving its transcriptional activator and repressor functions and which may underlie altered tumor biology with aberrant KLF9 expression.

Pärssinen J, Alarmo EL, Khan S, et al.
Identification of differentially expressed genes after PPM1D silencing in breast cancer.
Cancer Lett. 2008; 259(1):61-70 [PubMed] Related Publications
Amplification and overexpression of PPM1D (protein phosphatase magnesium-dependent 1 delta) has been observed in various cancer cell lines and primary tumors and has also been associated with cancers of poor prognosis. In addition to the negative feedback regulation of p38-p53 signaling, PPM1D inhibits other tumor suppressor activities and is involved in the control of DNA damage and repair pathways. To elucidate the functional significance of PPM1D in breast cancer, we employed RNA interference to downregulate PPM1D expression in BT-474, MCF7, and ZR-75-1 breast cancer cell lines and then investigated the effects of PPM1D silencing on global gene expression patterns and signaling pathways using oligonucleotide microarrays. We identified 1798 differentially expressed (at least a two-fold change) gene elements with functions related to key cellular processes, such as regulation of cell cycle, assembly of various intracellular structures and components, and regulation of signaling pathways and metabolic cascades. For instance, genes involved in apoptosis (NR4A1, RAB25, PLK1), formation of nucleosome structure (HIST1H2AC, HIST1H2BF, HIST1H2BO, HIST1H1D), and hormone related activities (NR4A1, ESR1, STC1) were among the differentially expressed genes. Overall, our findings suggest that PPM1D contributes to breast cancer associated phenotypic characteristics by directly or indirectly affecting several important cellular signaling pathways.

Korkola JE, Heck S, Olshen AB, et al.
In vivo differentiation and genomic evolution in adult male germ cell tumors.
Genes Chromosomes Cancer. 2008; 47(1):43-55 [PubMed] Related Publications
Germ cell tumors (GCTs) are the most common solid malignancy in young adult men, but the genes and genomic regions involved in their etiology are not fully defined. We report here an investigation of DNA copy number changes in GCTs using 1 Mb BAC arrays. As expected, 12p gain was the defining genomic alteration, occurring in 72/74 GCTs. Parallel expression profiling of these tumors identified potential oncogenes from gained regions (LYN and RAB25) and potential tumor suppressor genes in regions of loss (SYNPO2, TTC12, IGSF4, and EPB41L3). Notably, we observed specific genomic alterations associated with histology, including gain of 17p11.2-q21.32 and loss of 2p25.3 in embryonal carcinoma, gain of 8p23.3-12 and loss of 5p15.33-35.3, 11q23.1-25, and 13q12.11-34 in seminoma, and gain of 1q31.3-42.3, 3p, 14q11.2-32.33, and 20q and loss of 8q11.1-23.1 in yolk sac tumors (YST). Many significant genes that mapped to these regions had previously been associated with specific histologies, such as EOMES (chr3) and BMP2 (chr20) in YST and SPRY2 (chr13) and SOX17 (chr8) in seminomas. Additionally, our results suggest a model in which histologic differentiation of GCTs may drive genomic evolution.

Fan Y, Xin XY, Chen BL, Ma X
Knockdown of RAB25 expression by RNAi inhibits growth of human epithelial ovarian cancer cells in vitro and in vivo.
Pathology. 2006; 38(6):561-7 [PubMed] Related Publications
AIMS: Ovarian cancer is the leading cause of cancer death among gynaecological malignancies. Elevated expression of Rab25 has been seen in this malignancy. To better understand its role in maintaining the malignant phenotype, we used RNA interference (RNAi) directed against Rab25 in our study. RNAi provides a new, reliable method to investigate gene function and has the potential for gene therapy. The aim of the study was to examine the anti-tumour effects elicited by a decrease in the level of Rab25 by RNAi and its possible mechanism of action.
METHODS: According to the Rab25 mRNA sequence in Genbank, a pair of 64 nt oligonucleotides were designed and synthesised, each containing the sites of restriction endonuclease at both ends. Oligonucleotides were annealed and ligated with linearised pSUPER by ligase. The recombinants (named pSUPER/Rab25 siRNA) were finally sequenced and identified by enzyme cutting and sequencing. The human ovarian cell line A2780 was grown without transfection, transfection with empty vector and with pSUPER/Rab25 siRNA with electroporation. The inhibitory effect was examined by RT-PCR, MTT, FCM and tumour growth of athymic nude mice.
RESULTS: Rab25 siRNA expression vector was successfully constructed and identified by double endonuclease digestion. Sequence analysis of inserted fragment revealed the same sequence as synthesised siRNA oligonucleotides. Cells transfected with Rab25 siRNA can specifically knock down the transcription of Rab25, exhibiting cells with slower proliferation, increased apoptosis, and decreased tumour growth.
CONCLUSIONS: Rab25 siRNA expression vector has been successfully constructed, and it could inhibit the tumour growth both in vitro and in vivo. Our data suggest that the Rab25 signalling pathway plays a role in the regulation of cell proliferation and apoptosis in ovarian cancer cells, which indicates that the Rab25 gene plays a definite role in the development and aggressiveness of human ovarian cancer and should be further elucidated as a possible therapeutic target of ovarian cancer.

Davidson B, Zhang Z, Kleinberg L, et al.
Gene expression signatures differentiate ovarian/peritoneal serous carcinoma from diffuse malignant peritoneal mesothelioma.
Clin Cancer Res. 2006; 12(20 Pt 1):5944-50 [PubMed] Related Publications
PURPOSE: Ovarian/primary peritoneal serous carcinoma (OC/PPC) and diffuse peritoneal malignant mesothelioma (DMPM) are highly aggressive tumors that are closely related morphologically and histogenetically. It remains unclear whether both tumors are molecularly distinct neoplasms. The current study compared global gene expression patterns in OC/PPC and DMPM.
EXPERIMENTAL DESIGN: Ten OC/PPC and five DMPM effusions were analyzed for gene expression profiles using the Affymetrix U133 Plus 2 arrays and the dCHIP analysis program. 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 classified the samples into two groups: DMPM specimens versus OC/PPC specimens. A total of 189 genes that were differentially expressed in these two groups were selected based on statistical significance. Genes overexpressed in DMPM (n = 68) included calretinin, vitronectin, claudin 15, alpha4 laminin, hyaluronan synthase 1, cadherin 11, RAB7, v-maf, and the epidermal growth factor-containing fibulin-like extracellular matrix protein 1. Genes overexpressed in OC/PPC (n = 121) included insulin-like growth factor II (IGF-II); IGF-II binding protein 3; cyclin E1; folate receptors 1 and 3; RAB25; MUC4; endothelin-1; CD24; kallikreins 6, 7, and 8; claudins 3, 4, and 6; Notch3; and MMP-7. Quantitative real-time PCR validated the differential expression of 13 genes, and immunohistochemistry confirmed the differences for four gene products.
CONCLUSIONS: Expression profiling separates OC/PPC from DMPM and identifies a number of genes that are differentially expressed in these tumors. The molecular signatures unique to OC/PPC and DMPM should provide a molecular basis to study both tumors and new potential markers for facilitating their differential diagnosis.

Natrajan R, Williams RD, Hing SN, et al.
Array CGH profiling of favourable histology Wilms tumours reveals novel gains and losses associated with relapse.
J Pathol. 2006; 210(1):49-58 [PubMed] Related Publications
Despite the excellent survival of Wilms tumour patients treated with multimodality therapy, approximately 15% will suffer from tumour relapse, where response rates are markedly reduced. We have carried out microarray-based comparative genomic hybridisation on a series of 76 Wilms tumour samples, enriched for cases which recurred, to identify changes in DNA copy number associated with clinical outcome. Using 1Mb-spaced genome-wide BAC arrays, the most significantly different genomic changes between favourable histology tumours that did (n = 37), and did not (n = 39), subsequently relapse were gains on 1q, and novel deletions at 12q24 and 18q21. Further relapse-associated loci included losses at 1q32.1, 2q36.3-2q37.1, and gain at 13q31. 1q gains correlated strongly with loss of 1p and/or 16q. In 3 of 11 cases with concurrent 1p(-)/1q(+), a breakpoint was identified at 1p13. Multiple low-level sub-megabase gains along the length of 1q were identified using chromosome 1 tiling-path arrays. One such recurrent region at 1q22-q23.1 included candidate genes RAB25, NES, CRABP2, HDGF and NTRK1, which were screened for mRNA expression using quantitative RT-PCR. These data provide a high-resolution catalogue of genomic copy number changes in relapsing favourable histology Wilms tumours.

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