Downregulation of RASAL2 promotes the proliferation, epithelial-mesenchymal transition and metastasis of colorectal cancer cells

CAMSAP2 enhances lung cancer cell metastasis by mediating RASAL2 degradation

AIMS

Cancer metastasis significantly contributes to mortality in lung cancer patients. Calmodulin-regulated spectrin-associated protein family member 2 (CAMSAP2) plays a significant role in cancer cell migration; however, its role in lung cancer metastasis and the underlying mechanism remain largely unknown. The present study aimed to investigate the impact of CAMSAP2 on lung cancer.

MAIN METHODS

The clinical relevance of CAMSAP2 in lung cancer patients was assessed using public database. RNA interference experiments were conducted to investigate role of CAMSAP2 in cell migration through transwell and wound healing assays. Molecular mechanisms were explored by identifying the possible interacting partners and pathways using the BioGRID and KEGG pathway analyses. The impact of CAMSAP2 on Ras protein activator-like 2 (RASAL2)-mediated lung cancer metastasis was investigated through biochemical assays. Additionally, in vivo experimentation using a murine tail vein metastasis model was performed to comprehend CAMSAP2's influence on metastasis.

KEY FINDINGS

A high expression level of CAMSAP2 was associated with poor overall survival in lung cancer patients and it positively correlated with cell migration in non-small cell lung cancer (NSCLC) cell lines. Knockdown of CAMSAP2 inhibited lung cancer cell motility in vitro and metastasis in vivo. Proteomic and biochemical analyses revealed the interaction between CAMSAP2 and RASAL2, which facilitates the degradation of RASAL2 through the ubiquitin-proteasome system. These degradation processes resulted in the activation of the extracellular signal-regulated kinase (ERK) signaling pathway, thereby promoting lung cancer metastasis. Collectively, the results of this study suggest that CAMSAP2 is a crucial regulator of cancer cell migration and metastasis and a promising therapeutic target for lung cancer.

Germline variation in RASAL2 may predict survival in patients with RAS-activated colorectal cancer

BACKGROUND

Therapeutic agents that specifically target patients with RAS mutant colorectal cancer (CRC) are needed. We sought potential drug targets by relating genome-wide association study and survival data in patients with advanced CRC profiled for mitogen-activated protein kinase (MAPK) pathway mutations.

METHODS

In total, 694 patients from the clinical trials COIN and COIN-B had MAPK-activated CRCs (assigned as KRAS, NRAS, or BRAF mutant). Genome-wide single nucleotide polymorphism (SNP), gene, and gene-set analyses were performed to identify determinants of survival. For rs12028023 in RAS protein activator-like 2 (RASAL2), we studied its effect by MAPK pathway activation status (by comparing to 760 patients without MAPK-activated CRCs), MAPK gene mutation status, surface area of the primary tumor (as a marker of proliferation), and expression on RASAL2.

RESULTS

In MAGMA genome-wide analyses, RASAL2 was the most significant gene associated with survival (p = 2.0 × 10-5 ). Patients carrying the minor (A) allele in the lead SNP, rs12028023 in intron 1 of RASAL2, had a median increase in survival of 167 days as compared with patients carrying the major allele. rs12028023 was predictive for survival by MAPK-activation status (pZ-test  = 2.1 × 10-3 ). Furthermore, rs12028023 improved survival in patients with RAS mutant (hazard ratio [HR] = 0.62, 95% confidence intervals [CI] = 0.5-0.8, p = 3.4 × 10-5 ) but not BRAF mutant (p = 0.87) CRCs. The rs12028023 A-allele was associated with reduced surface area of the primary tumor (Beta = -0.037, standard error [SE] = 0.017, p = 3.2 × 10-2 ) and reduced RASAL2 expression in cultured fibroblasts (p = 1.6 × 10-11 ).

CONCLUSION

Our data demonstrate a prognostic role for RASAL2 in patients with MAPK-activated CRCs, with potential as a therapeutic target.

RASAL2 Deficiency Attenuates Hepatic Steatosis by Promoting Hepatic VLDL Secretion via the AKT/TET1/MTTP Axis

BACKGROUND AND AIMS

RAS protein activator like 2 (RASAL2) is a newly discovered metabolic regulator involved in energy homeostasis and adipogenesis. However, whether RASAL2 is involved in hepatic lipid metabolism remains undetermined. This study explored the function of RASAL2 and elucidated its potential mechanisms in nonalcoholic fatty liver disease (NAFLD).

METHODS

NAFLD models were established either by feeding mice a high-fat diet or by incubation of hepatocytes with 1 mM free fatty acids (oleic acid:palmitic acid=2:1). Pathological changes were observed by hematoxylin and eosin staining. Lipid accumulation was assessed by Oil Red O staining, BODIPY493/503 staining, and triglyceride quantification. The in vivo secretion rate of very low-density lipoprotein was determined by intravenous injection of tyloxapol. Gene regulation was analyzed by chromatin immunoprecipitation assays and hydroxymethylated DNA immunoprecipitation combined with real-time polymerase chain reaction.

RESULTS

RASAL2 deficiency ameliorated hepatic steatosis both in vivo and in vitro. Mechanistically, RASAL2 deficiency upregulated hepatic TET1 expression by activating the AKT signaling pathway and thereby promoted MTTP expression by DNA hydroxymethylation, leading to increased production and secretion of very low-density lipoprotein, which is the major carrier of triglycerides exported from the liver to distal tissues.

CONCLUSIONS

Our study reports the first evidence that RASAL2 deficiency ameliorates hepatic steatosis by regulating lipid metabolism through the AKT/TET1/MTTP axis. These findings will help understand the pathogenesis of NAFLD and highlight the potency of RASAL2 as a new molecular target for NAFLD.

Ras superfamily GTPase activating proteins in cancer: Potential therapeutic targets?

To search more therapeutic strategies for Ras-mutant tumors, regulators of the Ras superfamily involved in the GTP/GDP (guanosine triphosphate/guanosine diphosphate) cycle have been well concerned for their anti-tumor potentials. GTPase activating proteins (GAPs) provide the catalytic group necessary for the hydrolysis of GTPs, which accelerate the switch by cycling between GTP-bound active and GDP-bound inactive forms. Inactivated GAPs lose their function in activating GTPase, leading to the continuous activation of downstream signaling pathways, uncontrolled cell proliferation, and eventually carcinogenesis. A growing number of evidence has shown the close link between GAPs and human tumors, and as a result, GAPs are believed as potential anti-tumor targets. The present review mainly summarizes the critically important role of GAPs in human tumors by introducing the classification, function and regulatory mechanism. Moreover, we comprehensively describe the relationship between dysregulated GAPs and the certain type of tumor. Finally, the current status, research progress, and clinical value of GAPs as therapeutic targets are also discussed, as well as the challenges and future direction in the cancer therapy.

Transcriptome Profiling of A549 Xenografts of Nonsmall-cell Lung Cancer Treated with Qing-Re-Huo-Xue Formula

Lung cancer is one of the most common malignant tumors, and non-small cell lung cancer (NSCLC) accounts for 85% of all lung cancer cases. Chinese herbal formula Qing-Re-Huo-Xue (QRHXF) has shown antitumor effects in the NSCLC xenograft mouse model of Lewis cells. However, the molecular mechanisms underlying the antitumor effects of QRHXF remain unknown. In this study, an A549 xenograft mouse model was established, and the mice were then treated with QRHXF or vehicle through oral gavage. Tumor growth was monitored. Tumors were subsequently harvested, and RNA sequencing was performed. Compared with the control group, mice treated with QRHXF showed smaller tumor size and slower tumor growth. RNA sequencing results indicated 36 differentially expressed genes between QRHXF treated and control groups. 16 upregulated and 20 downregulated genes were identified. Enrichment analysis showed four differential expression genes (DEGs) related to tumor growth pathways RASAL2, SerpinB5, UTG1A4, and PDE3A. In conclusion, this study revealed that QRHXF could inhibit tumor growth in an A549 xenograft mouse model, and the target genes of QRHXF may include PDE3A, RASAL2, SERPIB5, and UTG1A4.

Perfluoroalkyl substances influence DNA methylation in school-age children highly exposed through drinking water contaminated from firefighting foam: a cohort study in Ronneby, Sweden

Perfluoroalkyl substances (PFASs) are widespread synthetic substances with various adverse health effects. A potential mechanism of toxicity for PFASs is via epigenetic changes, such as DNA methylation. Previous studies have evaluated associations between PFAS exposure and DNA methylation among newborns and adults. However, no study has evaluated how PFASs influence DNA methylation among children of school age. In this exploratory study with school-age children exposed to PFASs through drinking water highly contaminated from firefighting foams, we aimed to investigate whether exposure to PFASs was associated with alteration in DNA methylation and epigenetic age acceleration. Sixty-three children aged 7-11 years from the Ronneby Biomarker Cohort (Sweden) were included. The children were either controls with only background exposure (n = 32; perfluorooctane sulfonic acid: median 2.8 and range 1-5 ng/ml) or those exposed to very high levels of PFASs (n = 31; perfluorooctane sulfonic acid: median 295 and range 190-464 ng/ml). These two groups were matched on sex, age, and body mass index. Genome-wide methylation of whole-blood DNA was analyzed using the Infinium MethylationEPIC BeadChip kit. Epigenetic age acceleration was derived from the DNA methylation data. Twelve differentially methylated positions and seven differentially methylated regions were found when comparing the high-exposure group to the control group. There were no differences in epigenetic age acceleration between these two groups (P = 0.66). We found that PFAS exposure was associated with DNA methylation at specific genomic positions and regions in children at school age, which may indicate a possible mechanism for linking PFAS exposure to health effects.

RASAL2 suppresses the proliferative and invasive ability of PC3 prostate cancer cells

The RAS protein activator like 2 (RASAL2) negatively regulates RAS proto-oncogene which is activated by high mutation rate in cancer. Thus, RASAL2 expression could potentially limit the function of RAS in prostate cancer (PCa). Genome-wide DNA methylation analysis demonstrated that RASAL2 is differentially hypermethylated in PCa tissues compared to benign prostate tissues. The PCR analysis of RASAL2 mRNA transcript showed differential expression in a panel of prostate cell lines with most PCa showing lower RASAL2 expression compared to benign prostatic epithelial cells. In PCa PC3 cells, the ectopic expression of RASAL2 significantly inhibited cell proliferation and invasion and induced an S phase plus G2/M phase cell cycle arrest. Ingenuity Pathway Analysis (IPA) demonstrated a cross talk between RASAL2 and TNFα, a key cytokine in immune signaling pathway that is relevant in PCa. Over-expression of RASAL2 downregulated TNFα expression whereas the knockdown of RASAL2 caused increased expression of TNFα. Taken together, our data demonstrates tumor suppressor role for RASAL2 in human PCa cells, despite increased RAS oncogenic activity. Our observation provides a new mechanistic insight of RASAL2 expression in aberrant Ras expression and immune signaling in PCa cells suggesting a potential novel therapeutic target for PCa.

Inhibition of TMPRSS4 mediated epithelial-mesenchymal transition is critically involved in antimetastatic effect of melatonin in colorectal cancers

In the current study, the underlying anti-metastatic mechanism of melatonin contained in some edible plants was explored in association with transmembrane protease serine 4 (TMPRSS4) mediated metastasis and epithelial-mesenchymal transition (EMT) signaling in human HCT15 and SW620 colorectal cancer cells. Here, TMPRSS4 was highly expressed in HCT15, but was weakly expressed in SW620 cells. Melatonin exerted weak cytotoxicity, decreased invasion, adhesion, and migration, and attenuated the expression of TMPRSS4, cyclin E, pro-urokinase-type plasminogen activator (pro-uPA), p-signal transducer and activator of transcription 3 (p-STAT3), p-focal adhesion kinase (p-FAK), Snail and increased the expression of E-cadherin, p27, pp38 and p-Jun N-terminal kinases (p-JNK) in HCT15 cells. Conversely, overexpression of TMPRSS4 reduced the ability of melatonin to activate E-cadherin and reduce Snail. Furthermore, even in SW620 cells transfected with TMPRSS4-overexpression plasmid, melatonin effectively suppressed invasion and migration along with decreased expression of Snail, cyclin A, cyclin E, pro-uPA and p-FAK and increased expression of E-cadherin and p27. Overall, these findings provide evidence that melatonin suppresses metastasis in colon cancer cells via inhibition of TMPRSS4 mediated EMT.

PRKAA/AMPKα phosphorylation switches the role of RASAL2 from a suppressor to an activator of autophagy

RASAL2 (RAS protein activator like 2), a RASGTPase activating protein, can catalyze the hydrolysis of RAS-GTP into RAS-GDP to inactivate the RAS pathway in various types of cancer cells. However, the cellular function of RASAL2 remains elusive. Here we showed that RASAL2 can attenuate PRKAA/AMPKα phosphorylation by recruiting phosphatase PPM1B/pp2cβ, thus inhibiting the initiation of basal autophagy under normal conditions. In addition, we found that glucose starvation could induce dissociation of PPM1B from RASAL2 and then RASAL2 at S351 be phosphorylated by PRKAA, followed by the binding of phosphorylated-RASAL2 with to PIK3C3/VPS34-ATG14-BECN1/Beclin1 complex to increase PIK3C3 activity and autophagy. Furthermore, RASAL2 S351 phosphorylation facilitated breast tumor growth and correlated to poor clinical outcomes in breast cancer patients. Our study demonstrated that the phosphorylation status of RASAL2 S351 can function as a molecular switch to either suppress or promote AMPK-mediated autophagy. Inhibition of RASAL2 S351 phosphorylation might be a potential therapeutic strategy to overcome the resistance of AMPK-activation agents.

miR‑654‑3p suppresses cell viability and promotes apoptosis by targeting RASAL2 in non‑small‑cell lung cancer

Non-small-cell lung cancer (NSCLC) accounts for 80% of lung cancer cases, and is the leading cause of cancer-associated mortality worldwide. The present study aimed to investigate the roles of microRNA (miR)-654-3p in NSCLC. The expression levels of miR-654-3p and its target ras protein activator like 2 (RASAL2) mRNA were determined by reverse transcription-quantitative polymerase chain reaction; protein expression was analyzed by western blotting. Plasmids expressing miR-654-3p mimics were constructed and transfected into A549 cells. In addition, the viability and apoptotic rate of cells were analyzed by an MTT assay and flow cytometry, respectively. A luciferase reporter assay was performed to verify whether RASAL2 is a target of miR-654-3p. Downregulated miR-654-3p and upregulated RASAL2 expression were observed in tumor tissues and cells. Cell viability was suppressed and the apoptotic rate was increased in the miR-654-3p mimics-transfected cells compared with the control. Luciferase activity was decreased in the RASAL2-3′ untranslated region-wild type group treated with miR-654-3p mimics. Furthermore, the present study revealed that overexpression of miR-654-3p could suppress the viability and induce the apoptosis of cells by targeting RASAL2 in NSCLC. The present findings may contribute to developments in the treatment of NSCLC.

MicroRNA-876-5p represses the cell proliferation and invasion of colorectal cancer through suppressing YAP signalling via targeting RASAL2

Aberrant expression of microRNA-876-5p (miR-876-5p) is implicated in the progression of multiple human cancers. However, the potential role of miR-876-5p in colorectal cancer remains poorly understood. The purpose of the current study was to investigate the potential role of miR-876-5p in colorectal cancer. miR-876-5p expression was significantly downregulated in colorectal cancer tissues and cell lines compared with normal controls. Gain-of-function assays revealed that miR-876-5p overexpression effectively repressed the malignant behaviours of colorectal cancer cells, including cell proliferation, colony formation, and invasion. Bioinformatics analysis predicted that RAS protein activator like 2 (RASAL2), a potential oncogene for colorectal cancer, is a putative miR-876-5p target gene. A luciferase reporter assay confirmed that miR-876-5p directly binds to the 3'-untranslated region (UTR) of RASAL2. Furthermore, both RASAL2 messenger RNA (mRNA) and protein expression were negatively modulated by miR-876-5p in colorectal cancer cells. Notably, there was an inverse correlation between miR-876-5p and RASAL2 expression in colorectal cancer tissue specimens. Moreover, miR-876-5p was involved in regulating the activation of Yes-associated protein (YAP) signalling through inhibiting RASAL2. However, the miR-876-5p-mediated antitumour effect on colorectal cancer cells was partially reversed by restoring RASAL2 expression. Notably, miR-876-5p upregulation impeded the tumour growth of colorectal cancer cells in vivo in nude mice. Overall, these results demonstrated that miR-876-5p exerts an antitumour function in colorectal cancer by targeting RASAL2 to suppress YAP signalling activation. These findings highlight the importance of the miR-876-5p/RASAL2/YAP axis in colorectal cancer progression and suggest that miR-876-5p is a potential therapeutic target for treating colorectal cancer.

Pumping the brakes on RAS - negative regulators and death effectors of RAS

Mutations that activate the RAS oncoproteins are common in cancer. However, aberrant upregulation of RAS activity often occurs in the absence of activating mutations in the RAS genes due to defects in RAS regulators. It is now clear that loss of function of Ras GTPase-activating proteins (RasGAPs) is common in tumors, and germline mutations in certain RasGAP genes are responsible for some clinical syndromes. Although regulation of RAS is central to their activity, RasGAPs exhibit great diversity in their binding partners and therefore affect signaling by multiple mechanisms that are independent of RAS. The RASSF family of tumor suppressors are essential to RAS-induced apoptosis and senescence, and constitute a barrier to RAS-mediated transformation. Suppression of RASSF protein expression can also promote the development of excessive RAS signaling by uncoupling RAS from growth inhibitory pathways. Here, we will examine how these effectors of RAS contribute to tumor suppression, through both RAS-dependent and RAS-independent mechanisms.

Epigenetic changes in fibroblasts drive cancer metabolism and differentiation

Genomic changes that drive cancer initiation and progression contribute to the co-evolution of the adjacent stroma. The nature of the stromal reprogramming involves differential DNA methylation patterns and levels that change in response to the tumor and systemic therapeutic intervention. Epigenetic reprogramming in carcinoma-associated fibroblasts are robust biomarkers for cancer progression and have a transcriptional impact that support cancer epithelial progression in a paracrine manner. For prostate cancer, promoter hypermethylation and silencing of the RasGAP, RASAL3 that resulted in the activation of Ras signaling in carcinoma-associated fibroblasts. Stromal Ras activity initiated a process of macropinocytosis that provided prostate cancer epithelia with abundant glutamine for metabolic conversion to fuel its proliferation and a signal to transdifferentiate into a neuroendocrine phenotype. This epigenetic oncogenic metabolic/signaling axis seemed to be further potentiated by androgen receptor signaling antagonists and contributed to therapeutic resistance. Intervention of stromal signaling may complement conventional therapies targeting the cancer cell.

RASAL2 Plays Inconsistent Roles in Different Cancers

RAS protein activator like 2 (RASAL2) belongs to the RAS GTPase-activating protein family and plays an important role in several cancers, including ovarian cancer, nasopharyngeal carcinoma, malignant astrocytoma, renal cell carcinoma, bladder cancer, colorectal cancer, liver cancer, triple-negative breast cancer, lung adenocarcinoma, and pancreatic ductal adenocarcinoma. Traditionally, RASAL2 has been regarded as a tumor suppressor but recent studies have found that it is an oncogene in specific types of cancer, such as colorectal cancer, liver cancer, triple-negative breast cancer, triple-negative/estrogen receptor-negative breast cancer. In this review, we summarize the latest findings regarding RASAL2 in cancers, which may be important and useful in clinical practice. We discussed the specific functions and mechanisms of RASAL2 in different kinds of cancer cells (including its inhibition of invasion, metastasis and angiogenesis and its opposite effects), which may provide new directions for cancer research and treatments. RASAL2 exhibits different relationship with clinical cancer stage, histological grade, prognosis and overall survival in different kinds of tumor. RASAL2 is a potential prognostic factor and a new therapeutic target for diagnosis and treatment.

Evolutionary rate covariation analysis of E-cadherin identifies Raskol as a regulator of cell adhesion and actin dynamics in Drosophila

The adherens junction couples the actin cytoskeletons of neighboring cells to provide the foundation for multicellular organization. The core of the adherens junction is the cadherin-catenin complex that arose early in the evolution of multicellularity to link actin to intercellular adhesions. Over time, evolutionary pressures have shaped the signaling and mechanical functions of the adherens junction to meet specific developmental and physiological demands. Evolutionary rate covariation (ERC) identifies proteins with correlated fluctuations in evolutionary rate that can reflect shared selective pressures and functions. Here we use ERC to identify proteins with evolutionary histories similar to the Drosophila E-cadherin (DE-cad) ortholog. Core adherens junction components α-catenin and p120-catenin displayed positive ERC correlations with DE-cad, indicating that they evolved under similar selective pressures during evolution between Drosophila species. Further analysis of the DE-cad ERC profile revealed a collection of proteins not previously associated with DE-cad function or cadherin-mediated adhesion. We then analyzed the function of a subset of ERC-identified candidates by RNAi during border cell (BC) migration and identified novel genes that function to regulate DE-cad. Among these, we found that the gene CG42684, which encodes a putative GTPase activating protein (GAP), regulates BC migration and adhesion. We named CG42684 raskol (“to split” in Russian) and show that it regulates DE-cad levels and actin protrusions in BCs. We propose that Raskol functions with DE-cad to restrict Ras/Rho signaling and help guide BC migration. Our results demonstrate that a coordinated selective pressure has shaped the adherens junction and this can be leveraged to identify novel components of the complexes and signaling pathways that regulate cadherin-mediated adhesion.

The establishment of intercellular adhesions facilitated the genesis of multicellular organisms. The adherens junction, which links the actin cytoskeletons of neighboring cells, arose early in the evolution of multicellularity and selective pressures have shaped its function and molecular composition over time. In this study, we used evolutionary rate covariation (ERC) analysis to examine the evolutionary history of the adherens junction and to identify proteins that coevolved with the core adherens junction protein Drosophila E-cadherin (DE-cad). ERC analysis of DE-cad revealed a collection of proteins with similar evolutionary histories. We then tested the role of ERC-identified candidates in border cell migration in the fly egg chamber, a process that requires the coordinated regulation of cell-cell adhesion and cell motility. Among these, we found that a previously uncharacterized gene CG42684, which encodes a putative GTPase activating protein (GAP), regulates the collective cell migration of border cells, stabilizes cell-cell adhesions and regulates the actin dynamics. Our results demonstrate that components of the adherens junction share an evolutionary history and that ERC analysis is a powerful method to identify novel components of cell adhesion complexes in Drosophila.

The expression and function of RASAL2 in renal cell carcinoma angiogenesis

Patients with renal cell carcinoma (RCC) often develop resistance to antivascular drugs and eventually succumb to disease. However, the underlying molecular mechanism remains poorly understood. In this study, we demonstrated that RASAL2, a RAS GTPase-activating protein, played a tumor-suppressive role in RCC by targeting tumor angiogenesis. Firstly, we showed that RASAL2 was frequently epigenetically silenced in RCC, and its loss was negatively correlated with overall survival of RCC patients. Furthermore, we discovered that RASAL2 could inhibit RCC angiogenesis in vitro and in vivo. Mechanistically, we identified that RASAL2 could activate GSK3β by reducing Ser9 phosphorylation and subsequently decrease the expression of c-FOS and vascular endothelial growth factor A (VEGFA). Interruption of the p-GSK3β/c-FOS pathway with the specific inhibitor or small interfering RNA could reverse the expression of VEGFA, which may provide a new insight to prevent RCC from resistance to antivascular therapy.

RASAL2 promotes tumor progression through LATS2/YAP1 axis of hippo signaling pathway in colorectal cancer

Background

Patients with colorectal cancer (CRC) have a high incidence of regional and distant metastases. Although metastasis is the main cause of CRC-related death, its molecular mechanisms remain largely unknown.

Methods

Using array-CGH and expression microarray analyses, changes in DNA copy number and mRNA expression levels were investigated in human CRC samples. The mRNA expression level of RASAL2 was validated by qRT-PCR, and the protein expression was evaluated by western blot as well as immunohistochemistry in CRC cell lines and primary tumors. The functional role of RASAL2 in CRC was determined by MTT proliferation assay, monolayer and soft agar colony formation assays, cell cycle analysis, cell invasion and migration and in vivo study through siRNA/shRNA mediated knockdown and overexpression assays. Identification of RASAL2 involved in hippo pathway was achieved by expression microarray screening, double immunofluorescence staining and co-immunoprecipitation assays.

Results

Integrated genomic analysis identified copy number gains and upregulation of RASAL2 in metastatic CRC. RASAL2 encodes a RAS-GTPase-activating protein (RAS-GAP) and showed increased expression in CRC cell lines and clinical specimens. Higher RASAL2 expression was significantly correlated with lymph node involvement and distant metastasis in CRC patients. Moreover, we found that RASAL2 serves as an independent prognostic marker of overall survival in CRC patients. In vitro and in vivo functional studies revealed that RASAL2 promoted tumor progression in both KRAS/NRAS mutant and wild-type CRC cells. Knockdown of RASAL2 promoted YAP1 phosphorylation, cytoplasm retention and ubiquitination, therefore activating the hippo pathway through the LATS2/YAP1 axis.

Conclusions

Our findings demonstrated the roles of RASAL2 in CRC tumorigenesis as well as metastasis, and RASAL2 exerts its oncogenic property through LATS2/YAP1 axis of hippo signaling pathway in CRC.

Electronic supplementary material

The online version of this article (10.1186/s12943-018-0853-6) contains supplementary material, which is available to authorized users.

RASAL2 inhibits tumor angiogenesis via p-AKT/ETS1 signaling in bladder cancer

Muscle-invasive or metastatic bladder cancer (BCa) is a life-threatening disease for patients, and tumor angiogenesis is believed to play a critical role in the progression of BCa. However, its underlying mechanism of tumor angiogenesis is still poorly understood. In this study, we discovered that RASAL2, a RAS GTPase activating protein, could inhibit BCa angiogenesis based on our shRNA/siRNA knockdown or ectopic cDNA expression experiments. Mechanistically, RASAL2 downregulation could enhance the phosphorylation of AKT and then subsequently upregulate the expression of ETS1 and VEGFA. Furthermore, there was a negative correlation between RASAL2 and VEGFA or CD31 expression in subcutaneous xenograft and human BCa specimens. Taken together, we provide a new insight into the molecular mechanism of BCa progression, in which RASAL2 can be a new therapeutic target.