RhoB Acts as a Tumor Suppressor That Inhibits Malignancy of Clear Cell Renal Cell Carcinoma

RhoB regulates prostate cancer cell proliferation and docetaxel sensitivity via the PI3K-AKT signaling pathway

Docetaxel is a widely used first-line treatment for castration-resistant prostate cancer (CRPC). RhoB, a member of the Rho GTPase family, plays a major role in prostate cancer metastasis by modulating the PI3K-AKT signaling pathway. It is crucial in regulating cytoskeletal reassembly, cell migration, focal adhesion (FA) dynamics. To investigate RhoB's function in prostate cancer, CRISPR/Cas9 gene editing technique was utilized to knock out the RhoB gene in prostate cancer cells. Successful gene editing was confirmed by using T7 endonuclease I (T7EI) assays and Sanger sequencing. Knocking out RhoB enhanced epithelial-mesenchymal transition (EMT) and decreased the IC50 value of docetaxel in RhoB-knockout PC-3 cells. This suggests increased sensitivity to docetaxel. Furthermore, RhoB knockout prompted the migration and invasion of prostate cancer cells, effects that were reversed upon RhoB overexpression. Interestingly, RhoB status did not significantly influence the cell cycle of prostate cancer cells. RNA sequencing of PC-3 cells with either overexpressed or knock-out RhoB revealed that RhoB regulates pathways involved in FA, ECM receptor interaction, and PI3K-AKT signaling. These pathways directly influence the EMT process, cell migration, and invasion in prostate cancer cells. Notably, RhoB overexpression activated PI3K-AKT signaling when PC-3 cells were treated with low concentration of DTXL (50 nM, 72 h). This activation reduced DTXL's cytotoxicity, suggesting may confer chemoresistance via PI3K-AKT pathway activation.

Downregulation of RhoB Inhibits Cervical Cancer Progression and Enhances Cisplatin Sensitivity

RhoB, a member of the Rho GTPase family, has been implicated in the malignant progression of various cancer types. However, its role in cervical cancer (CC) remains unclear. Therefore, this study aims to elucidate the biological function of RhoB in CC and its relationship with cisplatin sensitivity. We analyzed data from the TCGA, GTEx, and GEO databases, revealing that RhoB mRNA expression is downregulated in CC tissues compared to normal cervical tissues. The further analysis of the TCGA database and Tongji samples showed that CC patients with a high RhoB expression had a shorter overall survival (OS). Subsequently, we found that the knockdown of RhoB inhibited the proliferation, migration, and invasion of cancer cells, while increasing apoptosis. Through Western blot (WB) analysis, we found that knocking down RhoB resulted in an increased expression of the epithelial marker E-cadherin, while the levels of N-cadherin, MMP2, MMP9, Vimentin, and Snail1 were reduced. Additionally, RhoB mRNA expression was upregulated in CC tissues after chemotherapy compared to CC tissues before chemotherapy. In CC cells, RhoB expression increased with cisplatin concentration, and the IC50 value decreased following RhoB knockdown. Moreover, the knockdown of RhoB could enhance the cellular apoptosis triggered by cisplatin. This study demonstrated that RhoB plays an oncogenic role in CC and that its knockdown could enhance the sensitivity of CC cells to cisplatin.

RhoB expression associated with chemotherapy response and prognosis in colorectal cancer

PURPOSE

To examine the role of RhoB expression in relation to chemotherapy response, clinical outcomes and associated signaling pathways in colorectal cancer patients.

MATERIALS AND METHODS

The study included 5 colon cancer cell lines, zebrafish embryos and 260 colorectal cancer patients treated with 5-fluorouracil (5-FU) and oxaliplatin (OXL). The methods consisted of CRISPR/Cas9, reactive oxygen species (ROS), caspase-3 activity, autophagy flux, in-silico RNA sequencing and immunohistochemistry. Gene expression analysis and pathway analysis were conducted using RNA-seq data.

RESULTS

All cancer lines tested, including SW480, SW480-KO13 (RhoB knockout), SW480-KO55 (RhoB knockout), HCT116 and HCT116-OE (RhoB overexpressed), exhibited cytotoxicity to 5-FU and OXL. RhoB knockout cell lines demonstrated significantly reduced migration compared to the control cell lines. Furthermore, RhoB played a role in caspase-3-dependent apoptosis, regulation of ROS production and autophagic flux. The mRNA sequencing data indicated lower expression levels of oncogenes in RhoB knockout cell lines. The zebrafish model bearing SW480-KO showed a light trend toward tumor regression. RhoB expression by immunohistochemistry in patients was increased from normal mucosa to tumor samples. In patients who received chemotherapy, high RhoB expression was related to worse survival compared to low RhoB expression. Furthermore, the molecular docking analysis revealed that OXL had a higher binding affinity for RhoB than 5-FU, with a binding affinity of -7.8 kcal/mol and HADDOCK predicted molecular interactions between RhoB and caspase 3 protein. Gene-set enrichment analysis supported these findings, showing that enrichment of DNA damage response pathway and p53 signaling in RhoB overexpression treatment group, while the RhoB knockout treatment group exhibited enrichment in the negative regulation pathway of cell migration.

CONCLUSION

RhoB was negatively associated with chemotherapy response and survival in colorectal cancers. Therefore, RhoB inhibition may enhance chemotherapeutic responses and patient survival.

Artificial intelligence fusion for predicting survival of rectal cancer patients using immunohistochemical expression of Ras homolog family member B in biopsy

Aim

The process of biomarker discovery is being accelerated with the application of artificial intelligence (AI), including machine learning. Biomarkers of diseases are useful because they are indicators of pathogenesis or measures of responses to therapeutic treatments, and therefore, play a key role in new drug development. Proteins are among the candidates for biomarkers of rectal cancer, which need to be explored using state-of-the-art AI to be utilized for prediction, prognosis, and therapeutic treatment. This paper aims to investigate the predictive power of Ras homolog family member B (RhoB) protein in rectal cancer.

Methods

This study introduces the integration of pretrained convolutional neural networks and support vector machines (SVMs) for classifying biopsy samples of immunohistochemical expression of protein RhoB in rectal-cancer patients to validate its biologic measure in biopsy. Features of the immunohistochemical expression images were extracted by the pretrained networks and used for binary classification by the SVMs into two groups of less and more than 5-year survival rates.

Results

The fusion of neural search architecture network (NASNet)-Large for deep-layer feature extraction and classifier using SVMs provided the best average classification performance with a total accuracy = 85%, prediction of survival rate of more than 5 years = 90%, and prediction of survival rate of less than 5 years = 75%.

Conclusions

The finding obtained from the use of AI reported in this study suggest that RhoB expression on rectal-cancer biopsy can be potentially used as a biomarker for predicting survival outcomes in rectal-cancer patients, which can be informative for clinical decision making if the patient would be recommended for preoperative therapy.

DDX17 modulates the expression and alternative splicing of genes involved in apoptosis and proliferation in lung adenocarcinoma cells

Background

The DEAD-box RNA-binding protein (RBP) DDX17 has been found to be involved in the tumorigenesis of many types of cancers. However, the role of DDX17 in lung adenocarcinoma (LUAD) remains unclear.

Methods

We silenced DDX17 expression in A549 LUAD cells by small interfering RNA (siRNA). Cell proliferation and apoptosis assays were performed to explore the functions of DDX17. Knockdown of DDX17 by siRNA significantly inhibited proliferation and induced apoptosis in A549 cells. We used high-throughput RNA sequencing (RNA-seq) to identify differentially expressed genes (DEGs) and alternative splicing (AS) events in DDX17 knockdown LUAD cells.

Results

DDX17 knockdown increased the expression levels of proapoptotic genes and decreased those of proproliferative genes. Moreover, the DDX17-regulated AS events in A549 cells revealed by computational analysis using ABLas software were strongly validated by quantitative reverse transcription-polymerase chain reaction (RT-qPCR) and were also validated by analysis of The Cancer Genome Atlas (TCGA)-LUAD dataset. These findings suggest that DDX17 may function as an oncogene by regulating both the expression and AS of proliferation- and apoptosis-associated genes in LUAD cells. Our findings may offer new insights into understanding the molecular mechanisms of LUAD and provide a new therapeutic direction for LUAD.

GTSE1 promotes tumor growth and metastasis by attenuating of KLF4 expression in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is one of the most common malignant tumors and is characterized by a poor prognosis. Although G2- and S -phase expressed-1 (GTSE1) is known to be involved in the progression and metastasis of various cancers, its significance and mechanism in ccRCC remain unknown. In the present study, we found that GTSE1 was overexpressed in ccRCC tissues, especially in metastatic samples. Moreover, high GTSE1 expression was positively correlated with higher pT stage, tumor size, clinical stage, and WHO/ISUP grade and worse prognosis. And GTSE1 expression served as an independent prognostic factor for overall survival (OS). In addition, GTSE1 knockdown inhibited ccRCC cell proliferation, migration, and invasion, and enhanced cell apoptosis in vitro and in vivo. GTSE1 was crucial for epithelial-mesenchymal transition (EMT) in ccRCC. Mechanistically, GTSE1 depletion could upregulate the expression of Krüppel-like factor 4 (KLF4), which acts as a tumor suppressor in ccRCC. Downregulation of KLF4 effectively rescued the inhibitory effect induced by GTSE1 knockdown and reversed the EMT process. Overall, our results revealed that GTSE1 served as an oncogene regulating EMT through KLF4 in ccRCC, and that GTSE1 could also serve as a novel prognostic biomarker and may represent a promising therapeutic target for ccRCC.

Active RhoA Exerts an Inhibitory Effect on the Homeostasis and Angiogenic Capacity of Human Endothelial Cells

Background

The small GTPase RhoA (Ras homolog gene family, member A) regulates a variety of cellular processes, including cell motility, proliferation, survival, and permeability. In addition, there are reports indicating that RhoA‐ROCK (rho associated coiled‐coil containing protein kinase) activation is essential for VEGF (vascular endothelial growth factor)‐mediated angiogenesis, whereas other work suggests VEGF‐antagonistic effects of the RhoA‐ROCK axis.

Methods and Results

To elucidate this issue, we examined human umbilical vein endothelial cells and human coronary artery endothelial cells after stable overexpression (lentiviral transduction) of constitutively active (G14V/Q63L), dominant‐negative (T19N), or wild‐type RhoA using a series of in vitro angiogenesis assays (proliferation, migration, tube formation, angiogenic sprouting, endothelial cell viability) and a human umbilical vein endothelial cells xenograft assay in immune‐incompetent NOD scid gamma mice in vivo. Here, we report that expression of active and wild‐type RhoA but not dominant‐negative RhoA significantly inhibited endothelial cell proliferation, migration, tube formation, and angiogenic sprouting in vitro. Moreover, active RhoA increased endothelial cell death in vitro and decreased human umbilical vein endothelial cell‐related angiogenesis in vivo. Inhibition of RhoA by C3 transferase antagonized the inhibitory effects of RhoA and strongly enhanced VEGF‐induced angiogenic sprouting in control‐treated cells. In contrast, inhibition of RhoA effectors ROCK1/2 and LIMK1/2 (LIM domain kinase 1/2) did not significantly affect RhoA‐related effects, but increased angiogenic sprouting and migration of control‐treated cells. In agreement with these data, VEGF did not activate RhoA in human umbilical vein endothelial cells as measured by a Förster resonance energy transfer–based biosensor. Furthermore, global transcriptome and subsequent bioinformatic gene ontology enrichment analyses revealed that constitutively active RhoA induced a differentially expressed gene pattern that was enriched for gene ontology biological process terms associated with mitotic nuclear division, cell proliferation, cell motility, and cell adhesion, which included a significant decrease in VEGFR‐2 (vascular endothelial growth factor receptor 2) and NOS3 (nitric oxide synthase 3) expression.

Conclusions

Our data demonstrate that increased RhoA activity has the potential to trigger endothelial dysfunction and antiangiogenic effects independently of its well‐characterized downstream effectors ROCK and LIMK.

RHO GTPase-Related Long Noncoding RNAs in Human Cancers

RHO GTPases are critical signal transducers that regulate cell adhesion, polarity, and migration through multiple signaling pathways. While all these cellular processes are crucial for the maintenance of normal cell homeostasis, disturbances in RHO GTPase-associated signaling pathways contribute to different human diseases, including many malignancies. Several members of the RHO GTPase family are frequently upregulated in human tumors. Abnormal gene regulation confirms the pivotal role of lncRNAs as critical gene regulators, and thus, they could potentially act as oncogenes or tumor suppressors. lncRNAs most likely act as sponges for miRNAs, which are known to be dysregulated in various cancers. In this regard, the significant role of miRNAs targeting RHO GTPases supports the view that the aberrant expression of lncRNAs may reciprocally change the intensity of RHO GTPase-associated signaling pathways. In this review article, we summarize recent advances in lncRNA research, with a specific focus on their sponge effects on RHO GTPase-targeting miRNAs to crucially mediate gene expression in different cancer cell types and tissues. We will focus in particular on five members of the RHO GTPase family, including RHOA, RHOB, RHOC, RAC1, and CDC42, to illustrate the role of lncRNAs in cancer progression. A deeper understanding of the widespread dysregulation of lncRNAs is of fundamental importance for confirmation of their contribution to RHO GTPase-dependent carcinogenesis.

High Expression of RhoBTB3 Predicts Favorable Chemothrapy Outcomes in non-M3 Acute Myeloid Leukemia

Background: The expression patterns and prognostic significance of the Rho family GTPases in acute myeloid leukemia have not been systematically studied yet.

Methods: In our study, we analyzed the expression patterns of 21 Rho family GTPases gene members in AML patients based on GEPIA database. 10 gene members with significant differential expression in AML tissue and healthy tissue were selected for subsequent research. Survival curve analysis in TCGA and GEO dataset preliminary showed that RhoBTB3 is related with the prognosis of non-M3 AML patients. The differential expression of RhoBTB3 on AML bone marrow and normal bone marrow was verified by RT-qPCR. We performed Kaplan-Meier survival analysis and Multivariate Cox analysis to assess the prognostic value of RhoBTB3 in non-M3 AML patients with different treatment regimens. Gene functional enrichment analysis of RhoBTB3 was performed using GO, KEGG and PPI network.

Results: The AML patients from TCGA database were partitioned into 2 groups based on different treatment regimens: chemotherapy group and allo-HSCT group. In chemotherapy group, patients with higher expression level of RhoBTB3 showed relatively longer OS and EFS, multivariate Cox analysis revealed high RhoBTB3 mRNA expression as an independent favorable prognostic factor. However, in allo-HSCT group, no significant difference of OS and EFS were found between RhoBTB3 high and low subgroups. Meanwhile, allo-HSCT could circumvent the unfavorable prognosis that was associated with downregulation of RhoBTB3. Functional enrichment analysis showed the association of RhoBTB3 expression with several fundamental physiological components and pathways, including extracellular matrix components, extracellular structure organization, and cytokine-cytokine receptor interaction.

Conclusions: Our study identified RhoBTB3 as a prognostic marker and may aid in the selection of the appropriate treatment options between chemotherapy and allo-HCST in non-M3 AML patients. Further researches are necessary to clarify the involvement of RhoBTB3 in the pathogenesis of AML.

Multi-omics analysis of tumor angiogenesis characteristics and potential epigenetic regulation mechanisms in renal clear cell carcinoma

BACKGROUND

Tumor angiogenesis, an essential process for cancer proliferation and metastasis, has a critical role in prognostic of kidney renal clear cell carcinoma (KIRC), as well as a target in guiding treatment with antiangiogenic agents. However, tumor angiogenesis subtypes and potential epigenetic regulation mechanisms in KIRC patient remains poorly characterized. System evaluation of angiogenesis subtypes in KIRC patient might help to reveal the mechanisms of KIRC and develop more target treatments for patients.

METHOD

Ten independent tumor angiogenesis signatures were obtained from molecular signatures database (MSigDB) and gene set variation analysis was performed to calculate the angiogenesis score in silico using the Cancer Genome Atlas (TCGA) KIRC dataset. Tumor angiogenesis subtypes in 539 TCGA-KIRC patients were identified using consensus clustering analysis. The potential regulation mechanisms was studied using gene mutation, copy number variation, and differential methylation analysis (DMA). The master transcription factors (MTF) that cause the difference in tumor angiogenesis signals were completed by transcription factor enrichment analysis.

RESULTS

The angiogenesis score of a prognosis related angiogenesis signature including 189 genes was significantly correlated with immune score, stroma score, hypoxia score, and vascular endothelial growth factor (VEGF) signal score in 539 TCGA KIRC patients. MMRN2, CLEC14A, ACVRL1, EFNB2, and TEK in candidate gene set showed highest correlation coefficient with angiogenesis score in TCGA-KIRC patients. In addition, all of them were associated with overall survival in both TCGA-KIRC and E-MTAB-1980 KIRC data. Clustering analysis based on 183 genes in angiogenesis signature identified two prognosis related angiogenesis subtypes in TCGA KIRC patients. Two clusters also showed different angiogenesis score, immune score, stroma score, hypoxia score, VEGF signal score, and microenvironment score. DMA identified 59,654 differential methylation sites between two clusters and part of these sites were correlated with tumor angiogenesis genes including CDH13, COL4A3, and RHOB. In addition, RFX2, SOX13, and THRA were identified as top three MTF in regulating angiogenesis signature in KIRC patients.

CONCLUSION

Our study indicate that evaluation the angiogenesis subtypes of KIRC based on angiogenesis signature with 183 genes and potential epigenetic mechanisms may help to develop more target treatments for KIRC patients. Video Abstract.

Cancer, Retrogenes, and Evolution

This review summarizes the knowledge about retrogenes in the context of cancer and evolution. The retroposition, in which the processed mRNA from parental genes undergoes reverse transcription and the resulting cDNA is integrated back into the genome, results in additional copies of existing genes. Despite the initial misconception, retroposition-derived copies can become functional, and due to their role in the molecular evolution of genomes, they have been named the “seeds of evolution”. It is convincing that retrogenes, as important elements involved in the evolution of species, also take part in the evolution of neoplastic tumors at the cell and species levels. The occurrence of specific “resistance mechanisms” to neoplastic transformation in some species has been noted. This phenomenon has been related to additional gene copies, including retrogenes. In addition, the role of retrogenes in the evolution of tumors has been described. Retrogene expression correlates with the occurrence of specific cancer subtypes, their stages, and their response to therapy. Phylogenetic insights into retrogenes show that most cancer-related retrocopies arose in the lineage of primates, and the number of identified cancer-related retrogenes demonstrates that these duplicates are quite important players in human carcinogenesis.

Differential Allele-Specific Expression Uncovers Breast Cancer Genes Dysregulated by Cis Noncoding Mutations

Identifying cancer-relevant mutations in noncoding regions is challenging due to the large numbers of such mutations, their low levels of recurrence, and difficulties in interpreting their functional impact. To uncover genes that are dysregulated due to somatic mutations in cis, we build upon the concept of differential allele-specific expression (ASE) and introduce methods to identify genes within an individual's cancer whose ASE differs from what is found in matched normal tissue. When applied to breast cancer tumor samples, our methods detect the known allele-specific effects of copy number variation and nonsense-mediated decay. Further, genes that are found to recurrently exhibit differential ASE across samples are cancer relevant. Genes with cis mutations are enriched for differential ASE, and we find 147 potentially functional noncoding mutations cis to genes that exhibit significant differential ASE. We conclude that differential ASE is a promising means for discovering gene dysregulation due to cis noncoding mutations.

Functional characterization of a candidate tumor suppressor gene, Mirror Image Polydactyly 1, in nasopharyngeal carcinoma

Mirror Image Polydactyly 1 (MIPOL1) is generally associated with congenital anomalies. However, its role in cancer development is poorly understood. Previously, by utilizing the functional complementation approach, microcell-mediated chromosome transfer (MMCT), a tumor suppressor gene, MIPOL1, was identified. MIPOL1 was confirmed to be downregulated in nasopharyngeal carcinoma (NPC) cells and tumor tissues, and re-expression of MIPOL1 induced tumor suppression. The aim of the current study is to further elucidate the functional tumor suppressive role of MIPOL1. In our study, with an expanded sample size of different clinical stages of NPC tumor tissues, we further confirmed the downregulation of MIPOL1 in different cancer stages. MIPOL1 re-expression down-regulated angiogenic factors and reduced phosphorylation of metastasis-associated proteins including AKT, p65, and FAK. In addition, MIPOL1 was confirmed to interact with a tumor suppressor, RhoB, and re-expression of MIPOL1 enhanced RhoB activity. The functional role of MIPOL1 was further validated by utilizing a panel of wild-type (WT) and truncated MIPOL1 expression constructs. The MIPOL1 tumor-suppressive effect can only be observed in the WT MIPOL1-expressing cells. In vitro and nude mice in vivo functional studies further confirmed the critical role of WT MIPOL1 in inhibiting migration, invasion and metastasis in NPC. Overall, our study provides strong evidence about the tumor-suppressive role of MIPOL1 in inhibiting angiogenesis and metastasis in NPC.

Arf6 regulates RhoB subcellular localization to control cancer cell invasion

The ADP-ribosylation factor 6 (Arf6) is a small GTPase that regulates endocytic recycling processes in concert with various effectors. Arf6 controls cytoskeletal organization and membrane trafficking; however, the detailed mechanisms of regulation remain poorly understood. Here, we report that Arf6 forms a complex with RhoB. The interaction between RhoB and Arf6 is mediated by the GCI (glycine, cysteine, and isoleucine) residues (188-190) of RhoB. Specific targeting of Arf6 to plasma membrane or mitochondrial membranes promotes recruitment and colocalization of RhoB to these membrane microdomains. Arf6 depletion promotes the loss of RhoB from endosomal membranes and leads to RhoB degradation through an endolysosomal pathway. This results in defective actin and focal adhesion dynamics and increased 3D cell migration upon activation of the Met receptor tyrosine kinase. Our findings identify a novel regulatory mechanism for RhoB localization and stability by Arf6 and establish the strict requirement of Arf6 for RhoB-specific subcellular targeting to endosomes and biological functions.

Regulation of RhoB Gene Expression during Tumorigenesis and Aging Process and Its Potential Applications in These Processes

RhoB, a member of the Ras homolog gene family and GTPase, regulates intracellular signaling pathways by interfacing with epidermal growth factor receptor (EGFR), Ras, and phosphatidylinositol 3-kinase (PI3K)/Akt to modulate responses in cellular structure and function. Notably, the EGFR, Ras, and PI3K/Akt pathways can lead to downregulation of RhoB, while simultaneously being associated with an increased propensity for tumorigenesis. Functionally, RhoB, part of the Rho GTPase family, regulates intracellular signaling pathways by interfacing with EGFR, RAS, and PI3K/Akt/mammalian target of rapamycin (mTOR), and MYC pathways to modulate responses in cellular structure and function. Notably, the EGFR, Ras, and PI3K/Akt pathways can lead to downregulation of RhoB, while simultaneously being associated with an increased propensity for tumorigenesis. RHOB expression has a complex regulatory backdrop consisting of multiple histone deacetyltransferase (HDACs 1 and 6) and microRNA (miR-19a, -21, and -223)-mediated mechanisms of modifying expression. The interwoven nature of RhoB’s regulatory impact and cellular roles in regulating intracellular vesicle trafficking, cell motion, and the cell cycle lays the foundation for analyzing the link between loss of RhoB and tumorigenesis within the context of age-related decline in RhoB. RhoB appears to play a tissue-specific role in tumorigenesis, as such, uncovering and appreciating the potential for restoration of RHOB expression as a mechanism for cancer prevention or therapeutics serves as a practical application. An in-depth assessment of RhoB will serve as a springboard for investigating and characterizing this key component of numerous intracellular messaging and regulatory pathways that may hold the connection between aging and tumorigenesis.

Targeted Quantitative Proteomic Approach for Probing Altered Protein Expression of Small GTPases Associated with Colorectal Cancer Metastasis

Genes encoding the small GTPases of the Ras superfamily are among the most frequently mutated or dysregulated in human cancer. No systematic studies, however, have yet been conducted for assessing the implications of small GTPases in the metastatic transformation of colorectal cancer (CRC). By utilizing a recently established high-throughput multiple-reaction monitoring (MRM)-based workflow together with stable isotope labeling by amino acids in cell culture (SILAC), we investigated comprehensively the relative expression of the small GTPase proteome in a pair of matched primary/metastatic CRC cell lines (SW480/SW620). Among the 83 quantified small GTPases, 25 exhibited at least a 1.5-fold difference in protein expression in SW480 and SW620 cells. In particular, SAR1B protein was found to be substantially down-regulated in SW620 relative to SW480 cells. In addition, bioinformatic analyses revealed that diminished SAR1B mRNA expression is significantly associated with higher CRC stages and unfavorable patient prognosis, in support of a potential role of SAR1B in suppressing CRC metastasis. In addition, diminished SAR1B expression could stimulate epithelial-mesenchymal transition (EMT), thereby promoting motility and in vitro metastasis of SW480 cells. In summary, we profiled systematically, by employing an MRM-based targeted proteomic method, the differential expression of small GTPase proteins in a matched pair of primary/metastatic CRC cell lines. Our results revealed the potential roles of SAR1B in suppressing CRC metastasis and in the prognosis of CRC patients.

miR-150-5p represses TP53 tumor suppressor gene to promote proliferation of colon adenocarcinoma

MicroRNAs (miRNAs) play a critical role in regulation of numerous biological processes and pathogenesis of a variety of diseases. In addition, miRNAs contribute to carcinogenesis by acting as oncogenic or tumor suppressive. Circulating miRNAs including miR-150-5p are associated with colorectal cancer progression, and the putative targets of miR-150-5p include tumor suppressor gene, TP53. Here we sought to investigate the role of miR-150-5p-TP53 signaling pathway in proliferation of colon cancer and to determine expression levels of miR-miR-150-5p and TP53 in colon adenocarcinoma and adjacent non-cancerous tissue samples, or in human colon adenocarcinoma cell lines. MTT assay was used to determine proliferation and apoptosis in cell lines. Furthermore, we used Western blot to determine levels of cell cycle regulators with anti-miR-150-5p or apoptosis with overexpression of TP53. Our results show that expression levels of miR-150-5p were significantly elevated in clinical specimens from cancer patients. We further showed that inhibition of miR-150-5p increased TP53, and in turn, suppression of proliferation of colon adenocarcinoma. Moreover, inhibition of miR-150-5p or overexpression of TP53 caused cell arrest or apoptosis in colon adenocarcinoma. Our results support that miR-150-5p-TP53 pathway plays an important role in regulation of proliferation, cell arrest, and apoptosis in colon cancer, and could be an attractive target for therapy.

Guzhi Zengsheng Zhitongwan, a Traditional Chinese Medicinal Formulation, Stimulates Chondrocyte Proliferation through Control of Multiple Genes Involved in Chondrocyte Proliferation and Differentiation

Chinese materia medica (CMM) are essential components of traditional Chinese medicine, and Chinese medicinal formulas consisting of 2 or more types of CMM are widely used. These formulations have played a pivotal role in health protection and disease control for thousands of years. Guzhi Zengsheng Zhitongwan (GZZSZTW), which represents one of the Chinese medicinal formulations, has been used for several decades to treat joint diseases. However, the exact molecular mechanism underlying its efficacy in treating osteoarthritis remains to be elucidated. In the present study, we investigated the effects of GZZSZTW on primary chondrocytes. We demonstrated that GZZSZTW significantly promoted chondrocyte viability, maintained chondrocytes in a continuous proliferative state, and prevented their further differentiation. These effects were achieved by the synergistic interactions of various herbs and their active components in GZZSZTW through an increase in the expression levels of functional genes participating in chondrocyte commitment and proliferation and a decrease in the expression levels of genes involved in chondrocyte differentiation. GZZSZTW treatment also decreased the expression levels of genes that inhibited chondrocyte proliferation. Thus, this study has greatly deepened the current knowledge about the molecular effects of GZZSZTW on chondrocytes. It has also shed new light on possible strategies to further prevent and treat cartilage-related diseases by using traditional Chinese medicinal formulations.

Identification of potential biomarkers in cervical cancer with combined public mRNA and miRNA expression microarray data analysis

Cervical cancer is the fourth most prevalent malignancy in females worldwide. Early diagnosis is key to improving survival rates. Molecular biomarkers are an important method for diagnosing a number of types of cancer, including cervical cancer. The present study utilized public data from three mRNA microarray datasets and one microRNA dataset to analyze the key genes involved in cervical cancer. The mRNA and microRNA expression profile datasets (GSE9750, GSE46857, GSE67522 and GSE30656) were downloaded from the Gene Expression Omnibus database (GEO). Differentially expressed genes (DEGs) and microRNAs (DEMs) were screened using the online tool GEO2R. By using the DEGs consistent across the three mRNA datasets, a functional and pathway enrichment analysis was performed using the Database for Annotation, Visualization and Integrated Discovery. A protein-protein interaction (PPI) network was constructed and module analysis performed using the Search Tool for the Retrieval of Interacting Genes. Validated target genes of the DEMs were identified using the miRecords website. Using the identified target genes of the DEMs, a survival analysis was performed using the OncoLnc online tool. A total of 73 DEGs and 19 DEMs were screened from the microarray expression profile datasets. ‘Integrin-mediated’, ‘proteolysis’ and ‘phosphoinositide 3 kinase-protein kinase 3’ signaling pathways were the most enriched in the DEGs. Three of the DEGs, including Ras homolog family member B (RhoB), stathmin 1 (STMN1) and cyclin D1 (CCNB1) were validated DEM target genes. The OncoLnc survival analysis identified that RhoB was associated with a significantly longer overall survival, whereas STMN1 was associated with a significantly reduced overall survival time in patients with cervical cancer. Finally, data from The Cancer Genome Atlas revealed an association between the mRNA expression levels of RhoB and STMN1, and the overall survival time for patients with cervical cancer. In conclusion, RhoB and STMN1 were identified as key genes that may provide potential targets for cervical cancer diagnosis and treatment.

MicroRNA-19a and microRNA-19b promote the malignancy of clear cell renal cell carcinoma through targeting the tumor suppressor RhoB

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal cell carcinoma, which shows high aggressiveness and lacks biomarkers. RhoB acts as a tumor suppressor that inhibits the progression of ccRCC. In the present study, we examined the effects of oncogenic microRNAs, miR-19a and miR-19b, on RhoB expression in ccRCC cells. The results showed that both miR-19a and miR-19b could directly target the 3′untranslated region (3’UTR) of RhoB, resulting in the reduced expression of RhoB. With RT-PCR analysis, we detected the increased expression of miR-19a and miR-19b in ccRCC tissues compared to adjacent non-tumor renal tissues. These data also demonstrated an exclusive negative correlation between miR-19a/19b and RhoB expression in ccRCC specimens and cell lines. In addition, the knockdown of RhoB or overexpression of miR-19a and miR-19b in ccRCC cells could promote cell proliferation, migration and invasion. These data demonstrate the direct roles of miR-19a and miR-19b on the repression of RhoB and its consequences on tumorigenesis, cancer cell proliferation and invasiveness. These results suggest the potential clinical impact of miR-19a and miR-19b as molecular targets for ccRCC.

RhoB: Team Oncogene or Team Tumor Suppressor?

Although Rho GTPases RhoA, RhoB, and RhoC share more than 85% amino acid sequence identity, they play very distinct roles in tumor progression. RhoA and RhoC have been suggested in many studies to contribute positively to tumor development, but the role of RhoB in cancer remains elusive. RhoB contains a unique C-terminal region that undergoes specific post-translational modifications affecting its localization and function. In contrast to RhoA and RhoC, RhoB not only localizes at the plasma membrane, but also on endosomes, multivesicular bodies and has even been identified in the nucleus. These unique features are what contribute to the diversity and potentially opposing functions of RhoB in the tumor microenvironment. Here, we discuss the dualistic role that RhoB plays as both an oncogene and tumor suppressor in the context of cancer development and progression.

RHOB expression controls the activity of serine/threonine protein phosphatase PP2A to modulate mesenchymal phenotype and invasion in non-small cell lung cancers

Metastatic dissemination is the cause of death in the vast majority of cancers, including lung cancers. In order to metastasize, tumor cells must undergo a well-known series of changes, however the molecular details of how they manage to overcome the barriers at each stage remain incomplete. One critical step is acquiring the ability to migrate through the extracellular matrix. Loss of expression of the RAS-related small GTPase RHOB is a common feature of lung cancer progression, and we recently reported that this induces an epithelial-to-mesenchymal transition (EMT) that is dependent on SLUG overexpression and E-Cadherin inhibition and is characterized by 3-dimensional cell shape reorganization and the increased invasiveness of bronchial cells. RHOB loss was found to induce AKT1 activation, which in turn activates RAC1 through its GEF TRIO. Further investigation of this pathway revealed that RHOB interacts with and positively regulates PP2A, one of the major cellular serine-threonine phosphatases, by recruiting its regulatory subunit B55. Here we discuss the role of this newly discovered RHOB/PP2A/AKT1/RAC1 pathway in relation to mesenchymal migration and invasion in lung cancer.