Rab27A mRNA Research Articles

PRR34-AS1 promotes exosome secretion of VEGF and TGF-β via recruiting DDX3X to stabilize Rab27a mRNA in hepatocellular carcinoma

BackgroundExosomes are deemed to be an important tool of intercellular communicators in cancer cells. Our study investigated the role of PRR34 long non-coding RNA antisense RNA 1 (PRR34-AS1) in regulating exosome secretion in hepatocellular carcinoma (HCC) cells.MethodsQuantitative real-time polymerase chain reaction (RT-qPCR) analyzed the expression of PRR34-AS1. We assessed the function of PRR34-AS1 on the biological changes of THLE-3 cells and HCC cells. The downstream interaction between RNAS was assessed by mechanistic experiments.ResultsPRR34-AS1 expression was upregulated in HCC cells in comparison to THLE-3 cells. PRR34-AS1 depletion repressed HCC cell proliferation, migration and invasion as well as EMT phenotype, while PRR34-AS1 up-regulation accelerated the malignant phenotypes of THLE-3 cells. PRR34-AS1 recruited DDX3X to stabilize the mRNA level of exosomal protein Rab27a. Moreover, PRR34-AS1 facilitated the malignant phenotypes of THLE-3 cells by elevating Rab27a expression to promote the exosome secretion of VEGF and TGF-β in HCC cells.ConclusionsThe current study revealed a novel function of PRR34-AS1 in accelerating exosome secretion in HCC cells and offered an insight into lncRNA function in the regulation of tumor cell biology.Graphical

Expression of Rab Prenylation Pathway Genes and Relation to Disease Progression in Choroideremia.

PurposeChoroideremia results from the deficiency of Rab Escort Protein 1 (REP1), encoded by CHM, involved in the prenylation of Rab GTPases. Here, we investigate whether the transcription and expression of other genes involved in the prenylation of Rab proteins correlates with disease progression in a cohort of patients with choroideremia.MethodsRates of retinal pigment epithelial area loss in 41 patients with choroideremia were measured using fundus autofluorescence imaging for up to 4 years. From lysates of cultured skin fibroblasts donated by patients (n = 15) and controls (n = 14), CHM, CHML, RABGGTB and RAB27A mRNA expression, and REP1 and REP2 protein expression were compared.ResultsThe central autofluorescent island area loss in patients with choroideremia occurred with a mean half-life of 5.89 years (95% confidence interval [CI] = 5.09–6.70), with some patients demonstrating relatively fast or slow rates of progression (range = 3.3–14.1 years). Expression of CHM mRNA and REP1 protein were significantly decreased in all patients. No difference in expression of CHML, RABGGTB, RAB27A, or REP2 was seen between patients and controls. No correlation was seen between expression of the genes analyzed and rates of retinal degeneration. Non-sense induced transcriptional compensation of CHML, a CHM-like retrogene, was not observed in patients with CHM variants predicted to undergo non-sense mediated decay.ConclusionsPatients with choroideremia, who are deficient for REP1, show normal levels of expression of other genes involved in Rab prenylation, which do not appear to play any modifying role in the rate of disease progression.Translational RelevanceThere remains little evidence for selection of patients for choroideremia gene therapy based on genotype.

Rab27A promotes cellular apoptosis and ROS production by regulating the miRNA-124-3p/STAT3/RelA signalling pathway in ulcerative colitis.

Ulcerative colitis (UC) is a multifactorial inflammatory disease, and increasing evidence has demonstrated that the mechanism of UC pathogenesis is associated with excessive cellular apoptosis and reactive oxygen species (ROS) production. However, their function and molecular mechanisms related to UC remain unknown. In this study, Rab27A mRNA and protein were proven to be overexpressed in intestinal epithelial cells of UC patients and DSS‐induced colitis mice, compared with control (P < 0.05). And Rab27A silencing inhibits inflammatory process in DSS‐induced colitis mice (P < 0.05). Then, it was shown that knockdown of Rab27A suppressed apoptosis and ROS production through modulation of miR‐124‐3p, whereas overexpression of Rab27A promoted apoptosis and ROS production in LPS‑induced colonic cells. In addition, enhanced expression of miR‐124‐3p attenuated apoptosis and ROS production by targeting regulation of STAT3 in LPS‑induced colonic cells. Mechanistically, we found Rab27A reduced the expression and activity of miR‐124‐3p to activate STAT3/RelA signalling pathway and promote apoptosis and ROS production in LPS‑induced colonic cells, whereas overexpression of miR‐124‐3p abrogated these effects of Rab27A. More importantly, animal experiments illustrated that ectopic expression of Rab27A promoted the inflammatory process, whereas overexpression of miR‐124‐3p might interfere with the inflammatory effect in DSS‐induced colitis mice. In summary, Rab27A might modulate the miR‐124‐3p/STAT3/RelA axis to promote apoptosis and ROS production in inflammatory colonic cells, suggesting that Rab27A as a novel therapeutic target for the prevention and treatment of UC patients.

Exosomal expression of RAB27A and its related lncRNA Lnc-RNA-RP11-510M2 in lung cancer

Objectives Examine the diagnostic role of serum exosomal RAB27A mRNA in lung cancer and evaluate the relation of LncRNAs to lung cancer in association to RAB27A mRNA in Egyptian population. Methods Exosomal RNA-based biomarkers RAB27A mRNA and Lnc-RNA-RP11-510M2.10 were selected based on bioinformatic methods, followed by RT-qPCR validation of their expression in serum of 20 patients with lung cancer, 10 patients with COPD and 10 healthy volunteers. we examined their expression in 10 bronchoalveolar lavage samples and assessed correlation with the serum levels. Results There was an inverse relationship between expression of serum exosomal RAB27A mRNA and Lnc-RNA-RP11-510M2.10 (r = −0.62, p = .00). Both serum exosomal RAB27A mRNA and Lnc-RNA-RP11-510M2.10 showed a significant positive and negative association with lung cancer patients respectively in comparison to patients with COPD and healthy persons (p < .001). Conclusion RAB27A mRNA and Lnc-RNA-RP11-510M2.10 could be used as diagnostic and prognostic biomarker tools for lung cancer.

Specific Decrease in B-Cell-Derived Extracellular Vesicles Enhances Post-Chemotherapeutic CD8+ T Cell Responses

Systemic immunosuppression greatly affects the chemotherapeutic antitumor effect. Here, we showed that CD19+ extracellular vesicles (EVs) from B cells through CD39 and CD73 vesicle-incorporated proteins hydrolyzed ATP from chemotherapy-treated tumor cells into adenosine, thus impairing CD8+ Tcell responses. Serum CD19+ EVs were increased in tumor-bearing mice and patients. Patients with fewer serum CD19+ EVs had a better prognosis after chemotherapy. Upregulated hypoxia-inducible factor-1α (HIF-1α) promoted B cells to release CD19+ EVs by inducing Rab27a mRNA transcription. Rab27a or HIF-1α deficiency in B cells inhibited CD19+ EV production and improved the chemotherapeutic antitumor effect. Silencing of Rab27a in B cells by inactivated Epstein-Barr viruses carrying Rab27a siRNA greatly improved chemotherapeutic efficacy in humanized immunocompromised NOD PrkdcscidIl2rg-/- mice. Thus, decreasing CD19+ EVs holds high potential to improve the chemotherapeutic antitumor effect.

MicroRNA-134-3p is a novel potential inhibitor of human ovarian cancer stem cells by targeting RAB27A

The cluster of microRNAs (miRNAs) in the DLK1-DIO3 genomic imprinted region contains several miRNAs that have a significant regulatory role in tumor proliferation and invasion. One of these miRNAs is miR-134-3p, and its expression changes significantly in human ovarian cancer stem cells (OCSCs) and in CD44−/CD133− ovarian cancer. The results of a luciferase assay showed that miR-134-3p silenced RAB27A by binding to the 3′-UTR of RAB27A mRNA. Overexpression of miR-134-3p in human OCSCs can not only inhibit the expression of RAB27A but also can effectively downregulate the expression of some tumor proliferation and invasion genes. Overexpression of miR-134-3p can not only inhibit the in vitro proliferation and cell cycle progression of human OCSCs but also can decrease the tumorigenicity in nude mice.

Abstract 3197: Exosome secretion in ovarian carcinoma

Abstract The purpose of this study is to elucidate the mechanism of exosome secretion in Ovarian Cancer (OC). OC is the leading cause of death from gynecological cancers in western countries. Exosomes, 30-100 nm vesicles, contain various lipids, proteins, and nucleic acids, exhibit paracrine bioactivities as well as distant transfer of regulatory messages to other cells. In our lab, the presence of OC derived exosomes accelerated cancerous pathologies in mice, thus determining OC derived exosomes as having a pro cancerous effect and therefore a worthy target for OC therapy. The precise mechanism of the biogenesis and release of exosomes has yet to be elucidated; however, several studies have revealed the involvement of nSmase2, Tsap6 and Rab27a/b genes in these processes. OC is characterized by primary solid tumors, solid metastases, and effusions to the peritoneal and pleural cavities as the tumor progresses. In order to develop a relevant model for solid tumors and effusions in vitro we utilized 3D Macro-porous alginate scaffolds and 3D OVCAR 8 cell line spheroids respectively. In the present study, we examined the expression of the above mentioned genes at the mRNA and protein levels in human ovarian cancer samples derived from primary, metastatic lesions and from effusion derived OC cells and compared the expression profile to that of cell lines utilizing in our 3D in vitro model. Our results show that in OC samples, nSMmase2, Tsap6 and Rab27a mRNA expression are significantly higher in effusions vs solid tumors (p&amp;lt;0.026, p&amp;lt;0.0001 and p&amp;lt;0.02, respectively). Surprisingly, the protein content of these genes are significantly lower in effusions vs. the solid samples in these very same samples (p&amp;lt;0.001-0.0001). This discrepancy is explained by the presence of nSMmase2, Tsap6 and Rab27a proteins in effusion fluid-derived exosomes. Clinical analysis shows that elevated nSmase2 and Tsap6 mRNA expression correlates with poor survival (p&amp;lt;0.036) and less favorable response to chemotherapy, respectively (p&amp;lt;0.027). Furthermore, Rab27a protein is lower in pleural effusions compared to peritoneal effusions (p&amp;lt;0.013). In our in vitro model, mRNA analysis of OVCAR8 cells grown on alginate scaffold and spheroids show a higher expression of Tsap6 and Rab27a in spheroid cultures vs. scaffold cultures, corresponding with higher expression of these same genes in effusions vs. solid tumors in OC. To the best of our knowledge, this is the first study to attempt to develop a 3D in vitro model for the various forms of OC that will enable research on the exosome secretion mechanism in this disease, hopefully leading to a fuller understanding of the exosomes secretion process and to the development novel therapies to address this disease. Citation Format: Esther C. Broner, Tali Tavor Re'em, Claes Tropé, Ben Davidson, Reuven Reich. Exosome secretion in ovarian carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3197. doi:10.1158/1538-7445.AM2015-3197

High Rab27A expression indicates favorable prognosis in CRC.

BackgroundRab27A is a peculiar member in Rab family and has been suggested to play essential roles in the development of human cancers. However, the association between Rab27A expression and clinicopathological characteristics of colorectal cancer (CRC) has not been elucidated yet.MethodsOne-step quantitative real-time polymerase chain reaction (qPCR) test with 18 fresh-frozen CRC samples and immunohistochemistry (IHC) analysis in 112 CRC cases were executed to evaluate the relationship between Rab27A expression and the clinicopathological features of CRC. Cox regression and Kaplan-Meier survival analyses were performed to identify the prognostic factors for 112 CRC patients.ResultsThe results specified that the expression levels of Rab27A mRNA and protein were significantly higher in CRC tissues than that in matched non-cancerous tissues, in both qPCR test (p = 0.029) and IHC analysis (p = 0.020). The IHC data indicated that the Rab27A protein expression in CRC was statistically correlated with lymph node metastasis (p = 0.022) and TNM stage (p = 0.026). Cox multi-factor analysis and Kaplan-Meier method suggested Rab27A protein expression (p = 0.012) and tumor differentiation (p = 0.004) were significantly associated with the overall survival of CRC patients.ConclusionThe data indicated the differentiate expression of Rab27A in CRC tissues and matched non-cancerous tissues. Rab27A may be used as a valuable prognostic biomarker for CRC patients.

Scientific Program 2012 ISEV meeting Wednesday 18th April

Cancer cells implement various exocytic routes, modulated by small Rab GTPases, to relay crucial information for fostering growth, invasion and matrix degradation. We investigated the biological role and expression status of Rab27B, a regulator of exosome release, in breast cancer. Rab27B-upregulation in estrogen receptor (ER)-positive breast cancer cells promoted G1/S phase cell cycle transition and increased proliferation, F-actin reorganization and invasion in cell culture and invasive tumor growth and hemorrhagic ascites in a xenograft mouse model. Proteomics of purified Rab27B vesicles and the secretome of Rab27B-expressing breast cancer cells were identified HSP90a as key proinvasive growth regulator. HSP90a secretion occurred in a Rab27B-dependent manner and was required for MMP-2 activation. Endogenous Rab27B mRNA and protein, but not Rab3D and Rab27A mRNA, was associated with lymph node metastasis and differentiation grade in ER-positive breast cancer samples. In conclusion, Rab27B regulates invasive growth and metastasis in ER-positive breast cancer cell lines, and increased expression is associated with poor prognosis in humans. Because of the relationship between Rab27B and cancer progression, elucidating the role of exosomes in metastatic niche formation will be the next step forward in cancer research.

Differential expression of Rab27A/B correlates with clinical outcome in hepatocellular carcinoma

To investigate the association of Rab27A and Rab27B expression with clinicopathological characteristics and prognosis of hepatocellular carcinoma (HCC). We used reverse transcription polymerase chain reaction (RT-PCR), real-time PCR, and Western blotting to detect Rab27A and Rab27B mRNA and protein expression in 5 human HCC lines and the immortalized hepatic HL-7702 cell line. We further examined 148 primary HCC samples matched with adjacent normal tissue and 80 non-HCC specimens by immunohistochemistry to evaluate the correlation of Rab27A and Rab27B expression with clinicopathological features and prognosis. Our data showed that Rab27A and Rab27B were differentially expressed in cell lines and primary HCC tumors. Rab27A mRNA and protein were detected in 67% (4/6) of human cell lines and 80% (4/5) of HCC cell lines, while Rab27B was found in 50% (3/6) of human lines and 40% (2/5) of HCC lines. Rab27A expression was higher in primary HCC (46.2%, 66/143) than in matched adjacent tissue (24.3%, 33/136, P < 0.001), whereas immunopositivity for Rab27B was lower in primary HCC (57.4%, 81/141) than in matched adjacent tissue (87.5%, 119/136, P < 0.001). Analysis of clinicopathological characteristics of 148 HCC specimens revealed significant correlations between Rab27A and Rab27B expression and tumor tumor-node-metastasis (TNM) classification (P = 0.046 and P = 0.027, respectively), and between strong Rab27A expression and tumor differentiation grade (P = 0.008). Survival analyses revealed that patients with Rab27A(+) or Rab27B(+) tumors had significantly reduced overall survival compared with that of patients with Rab27A(-) or Rab27B(-) tumors (P = 0.015 and P = 0.005, respectively). Risk analyses revealed that Rab27B(+) and TNM III-IV were independent poor prognosis factors associated with a 3.36- and 3.37-fold higher relative risk of death, respectively. Rab27A and Rab27B expression were closely correlated with tumor progression and can be valuable prognostic indicators for HCC patients.

Effect of the Secretory Small GTPase Rab27B on Breast Cancer Growth, Invasion, and Metastasis

BACKGROUND Secretory GTPases like Rab27B control vesicle exocytosis and deliver critical proinvasive growth regulators into the tumor microenvironment. The expression and role of Rab27B in breast cancer were unknown. METHODS Expression of green fluorescent protein (GFP) fused with wild-type Rab3D, Rab27A, or Rab27B, or Rab27B point mutants defective in GTP/GDP binding or geranylgeranylation, or transient silencing RNA to the same proteins was used to study Rab27B in estrogen receptor (ER)-positive human breast cancer cell lines (MCF-7, T47D, and ZR75.1). Cell cycle progression was evaluated by flow cytometry, western blotting, and measurement of cell proliferation rates, and invasion was assessed using Matrigel and native type I collagen substrates. Orthotopic tumor growth, local invasion, and metastasis were analyzed in mouse xenograft models. Mass spectrometry identified proinvasive growth regulators that were secreted in the presence of Rab27B. Rab27B protein levels were evaluated by immunohistochemistry in 59 clinical breast cancer specimens, and Rab3D, Rab27A, and Rab27B mRNA levels were analyzed by quantitative real-time polymerase chain reaction in 20 specimens. Statistical tests were two-sided. RESULTS Increased expression of Rab27B promoted G(1) to S phase cell cycle transition, proliferation and invasiveness of cells in culture, and invasive tumor growth and hemorrhagic ascites production in a xenograft mouse model (n = 10; at 10 weeks, survival of MCF-7 GFP- vs GFP-Rab27B-injected mice was 100% vs 62.5%, hazard ratio = 0.26, 95% confidence interval = 0.08 to 0.88, P = .03). Mass spectrometric analysis of purified Rab27B-secretory vesicles identified heat-shock protein 90alpha as key proinvasive growth regulator. Heat-shock protein 90alpha secretion was Rab27B-dependent and was required for matrix metalloproteinase-2 activation. All Rab27B-mediated functional responses were GTP- and geranylgeranyl-dependent. Presence of endogenous Rab27B mRNA and protein, but not of Rab3D or Rab27A mRNA, was associated with lymph node metastasis (P < .001) and differentiation grade (P = .001) in ER-positive human breast tumors. CONCLUSIONS Rab27B regulates invasive growth and metastasis in ER-positive breast cancer cell lines, and increased expression is associated with poor prognosis in humans.

Griscelli syndrome-type 2 in twin siblings: case report and update on RAB27A human mutations and gene structure

Griscelli syndrome (GS) is a rare autosomal recessive disorder caused by mutation in the MYO5A (GS1, Elejalde), RAB27A (GS2) or MLPH (GS3) genes. Typical features of all three subtypes of this disease include pigmentary dilution of the hair and skin and silvery-gray hair. Whereas the GS3 phenotype is restricted to the pigmentation dysfunction, GS1 patients also show primary neurological impairment and GS2 patients have severe immunological deficiencies that lead to recurrent infections and hemophagocytic syndrome. We report here the diagnosis of GS2 in 3-year-old twin siblings, with silvery-gray hair, immunodeficiency, hepatosplenomegaly and secondary severe neurological symptoms that culminated in multiple organ failure and death. Light microscopy examination of the hair showed large, irregular clumps of pigments characteristic of GS. A homozygous nonsense mutation, C-T transition (c.550C>T), in the coding region of the RAB27A gene, which leads to a premature stop codon and prediction of a truncated protein (R184X), was found. In patient mononuclear cells, RAB27A mRNA levels were the same as in cells from the parents, but no protein was detected. In addition to the case report, we also present an updated summary on the exon/intron organization of the human RAB27A gene, a literature review of GS2 cases, and a complete list of the human mutations currently reported in this gene. Finally, we propose a flow chart to guide the early diagnosis of the GS subtypes and Chédiak-Higashi syndrome.

Differential expression and activation of Rab27A in human eosinophils: Relationship to blood eosinophilia

Eosinophil degranulation is thought to play a pathophysiological role in asthma. Rab27A is a GTP-binding protein that is known to be essential for the degranulation of several leukocyte subsets and thus may be essential for eosinophil granule exocytosis. Here, we show that Rab27A mRNA and protein are expressed in human eosinophils. We have developed a novel assay to assess Rab27A activation and have found a similar activation pattern of this protein upon stimulation of eosinophils, neutrophils and NK cells suggesting a similar function in these cell types. Interestingly, Rab27A expression was elevated in eosinophils from asthmatic donors. Furthermore, eosinophils from eosinophilic donors displayed more rapid Rab27A activation kinetics than those from donors with lower eosinophil counts. Given that elevated blood eosinophil numbers correlate with increased priming of eosinophils, this pattern of Rab27A activation suggests differential protein expression in activated cells may allow eosinophils to degranulate more rapidly upon stimulation.

Regulation of the expression of components of the exocytotic machinery of insulin-secreting cells by microRNAs

Fine-tuning of insulin secretion from pancreatic beta-cells participates in blood glucose homeostasis. Defects in this process can lead to chronic hyperglycemia and diabetes mellitus. Several proteins controlling insulin exocytosis have been identified, but the mechanisms regulating their expression remain poorly understood. Here, we show that two non-coding microRNAs, miR124a and miR96, modulate the expression of proteins involved in insulin exocytosis and affect secretion of the beta-cell line MIN6B1. miR124a increases the levels of SNAP25, Rab3A and synapsin-1A and decreases those of Rab27A and Noc2. Inhibition of Rab27A expression is mediated by direct binding to the 3'-untranslated region of Rab27A mRNA. The effect on the other genes is indirect and linked to changes in mRNA levels. Over-expression of miR124a leads to exaggerated hormone release under basal conditions and a reduction in glucose-induced secretion. miR96 increases mRNA and protein levels of granuphilin, a negative modulator of insulin exocytosis, and decreases the expression of Noc2, resulting in lower capacity of MIN6B1 cells to respond to secretagogues. Our data identify miR124a and miR96 as novel regulators of the expression of proteins playing a critical role in insulin exocytosis and in the release of other hormones and neurotransmitters.

Evidence that Griscelli Syndrome with Neurological Involvement Is Caused by Mutations in RAB27A, Not MYO5A

Griscelli syndrome (GS), a rare autosomal recessive disorder, is characterized by partial albinism, along with immunologic abnormalities or severe neurological impairment or both. Mutations in one of two different genes on chromosome 15q can cause the different subtypes of GS. Most patients with GS display the hemophagocytic syndrome and have mutations in RAB27A, which codes for a small GTPase. Two patients with neurological involvement have mutations in MYO5A, which codes for an actin-based molecular motor. The RAB27A and MYO5A gene products interact with each other and function in vesicle trafficking. We report the molecular basis of GS in a Muslim Arab kindred whose members have extremely variable neurological involvement, along with the hemophagocytic syndrome and immunologic abnormalities. The patients have normal MYO5A genes but exhibit a homozygous 67.5-kb deletion that eliminates RAB27A mRNA and immunocytofluorescence-detectable protein. We also describe the molecular organization of RAB27A and a multiplex polymerase chain reaction assay for the founder deletion in this kindred. Finally, we propose that all patients with GS have RAB27A mutations and immunologic abnormalities that sometimes result in secondary neurological involvement. The two patients described elsewhere who have MYO5A mutations and neurological complications but no immunologic defects may not have GS but instead may have Elejalde syndrome, a condition characterized by mild hypopigmentation and severe, primary neurological abnormalities.