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

Unraveling a novel hippo-associated immunological prognostic signature: The contribution of SERPINE1 in facilitating colorectal cancer progression via the notch signaling pathway

BACKGROUND

Accumulating evidence demonstrated that Hippo signaling pathway is implicated in tumor initiation and progression. However, there have been limited studies on establishing signatures utilizing genes related to the Hippo pathway to evaluate prognosis and clinical efficacy in colorectal cancer (CRC) patients.

METHODS

Hippo pathway-associated genes with prognostic significance were identified in the TCGA database. Subsequently, a prognostic signature associated with the Hippo pathway was constructed using Cox and LASSO regression analyses. Survival analysis, ROC analysis, and stratified analyses were conducted to appraise the performance effect of our prognostic model. We also explored the relationship between the risk score and tumor immune microenvironment. Furthermore, GO analyses and GSEA were performed for SERPINE1. Additional experiments were conducted to illuminate the underlying function and possible mechanism of SERPINE1 in CRC cell proliferation and migration.

RESULTS

We identified 58 differentially expressed genes associated with Hippo pathway that have prognostic significance in CRC. Among them, five genes (PPP2CB, SERPINE1, WNT5A, TCF7L1, and LEF1) were selected to establish a prognostic signature for CRC. Multivariate analysis demonstrated that this signature exhibited excellent diagnostic and prognostic performance, providing maximum benefits for CRC patients. In accordance with the prognostic signatures, the cases were divided into low-risk and high-risk groups. Remarkably, the high-risk group displayed lower immune scores, reduced immune cell infiltration, and decreased expression of immune checkpoints. Low-risk group could more possibly benefit from conventional chemotherapeutic and targeted therapies. CRC exhibited significantly elevated expression of SERPINE1, which was linked to worst overall survival. Moreover, inhibition of SERPINE1 suppressed proliferation, invasion, and migration of CRC cells via Notch pathway.

CONCLUSIONS

To sum up, we established a novel immunological prognostic signature utilizing genes associated with the Hippo pathway. This signature offers accurate prognostic prediction and can guide individualized therapy for patients with CRC.

Role of Hippo pathway dysregulation from gastrointestinal premalignant lesions to cancer

BACKGROUND

First identified in Drosophila melanogaster, the Hippo pathway is considered a major regulatory cascade controlling tissue homeostasis and organ development. Hippo signaling components include kinases whose activity regulates YAP and TAZ final effectors. In response to upstream stimuli, YAP and TAZ control transcriptional programs involved in cell proliferation, cytoskeletal reorganization and stemness.

MAIN TEXT

While fine tuning of Hippo cascade components is essential for maintaining the balance between proliferative and non-proliferative signals, pathway signaling is frequently dysregulated in gastrointestinal cancers. Also, YAP/TAZ aberrant activation has been described in conditions characterized by chronic inflammation that precede cancer development, suggesting a role of Hippo effectors in triggering carcinogenesis. In this review, we summarize the architecture of the Hippo pathway and discuss the involvement of signaling cascade unbalances in premalignant lesions of the gastrointestinal tract, providing a focus on the underlying molecular mechanisms.

CONCLUSIONS

The biology of premalignant Hippo signaling dysregulation needs further investigation in order to elucidate the evolutionary trajectories triggering cancer inititation and develop effective early therapeutic strategies targeting the Hippo/YAP pathway.

Chromatin accessibility complex subunit 1 enhances tumor growth by regulating the oncogenic transcription of YAP in breast and cervical cancer

Background

As a component of chromatin remodeling complex, chromatin accessibility complex subunit 1 (CHRAC1) is critical in transcription and DNA replication. However, the significance of CHRAC1 in cancer progression has not been investigated extensively. This research aimed to determine the function of CHRAC1 in breast and cervical cancer and elucidate the molecular mechanism.

Methods

The Bio-ID method was used to identify the interactome of transcriptional activator Yes-associated protein (YAP) and the binding between YAP and CHRAC1 was verified by immunofluorescence. CCK8, colony formation and subcutaneous xenograft assays were conducted to explore the function of CHRAC1 in cancer cell proliferation. RNA-seq analysis and RT-PCR were used to analyze the transcription program change after CHRAC1 ablation. The diagnostic value of CHRAC1 was analyzed by TCGA database and further validated by immunohistochemistry staining.

Results

In the current study, we found that the chromatin remodeler CHRAC1 was a potential YAP interactor. CHRAC1 depletion suppressed breast and cervical cancer cell proliferation and tumor growth. The potential mechanism may be that CHRAC1 interacts with YAP to facilitate oncogenic transcription of YAP target genes in Hippo pathway, thereby promoting tumorigenesis. CHRAC1 was elevated in cervical and breast cancer biopsies and the upregulation correlated with shorter survival, poor pathological stages and metastasis of cancer patients. Moreover, CHRAC1 expression was statistically associated with YAP in breast and cervical cancer biopsies.

Conclusions

These findings highlight that CHRAC1 contributes to cancer progression through regulating the oncogenic transcription of YAP, which makes it a potential therapeutic target for cancer treatment.

Uncovering the dynamics of cellular responses induced by iron-carbohydrate complexes in human macrophages using quantitative proteomics and phosphoproteomics

Iron-carbohydrate complexes are widely used to treat iron deficiencies. Macrophages play a crucial role in the uptake and fate of these nanomedicines, however, how complexed iron carbohydrates are taken up and metabolized by macrophages is still not fully understood. Using a (phospho-)proteomics approach, we assessed differences in protein expression and phosphorylation in M2 macrophages triggered by iron sucrose (IS). Our results show that IS alters the expression of multiple receptors, indicative of a complex entry mechanism. Besides, IS induced an increase in intracellular ferritin, the loss of M2 polarization, protective mechanisms against ferroptosis, and an autophagic response. These data indicate that macrophages can use IS as a source of iron for its storage and later release, however, the excess of iron can cause oxidative stress, which can be successfully regulated by the cells. When comparing IS with ferric carboxymaltose (FCM) and iron isomaltoside-1000 (IIM), complexes with a higher carbohydrate ligand stability, we observed that FCM and IIM are metabolized at a slower rate, and trigger M2 polarization loss to a lower extent. These results indicate that the surface characteristics of the iron-carbohydrate complexes may influence the cell responses. Our data show that the application of (phospho-)proteomics can lead to a better understanding of metabolic processes, including the uptake, biodegradation and bioavailability of nanomedicines.

Spatial immunophenotypes predict clinical outcome in intrahepatic cholangiocarcinoma

Background & Aims

Intrahepatic cholangiocarcinoma (iCCA) is a severe malignant tumour that shows only modest responses to immunotherapy. We aimed to identify the spatial immunophenotypes of iCCA and delineate potential immune escape mechanisms.

Method

Multiplex immunohistochemistry (mIHC) was performed to quantitatively evaluate the distribution of 16 immune cell subsets in intratumour, invasive margin and peritumour areas in a cohort of 192 treatment-naïve patients with iCCA. Multiregion unsupervised clustering was used to determine three spatial immunophenotypes, and multiomics analyses were carried out to explore functional differences.Results: iCCA displayed a region-specific distribution of immune cell subsets with abundant CD15⁺ neutrophil infiltration in intratumour areas. Three spatial immunophenotypes encompassing inflamed (35%), excluded (35%) and ignored (30%) phenotypes were identified. The inflamed phenotype showed characteristics of abundant immune cell infiltration in intratumour areas, increased PD-L1 expression and relatively favourable overall survival. The excluded phenotype with a moderate prognosis was characterized by immune cell infiltration restricted to the invasive margin or peritumour areas and upregulation of activated hepatic stellate cells, extracellular matrix and Notch signalling pathways. The ignored phenotype, with scarce immune cell infiltration across all subregions, was associated with MAPK signalling pathway elevation and a poor prognosis. The excluded and ignored phenotypes, constituting non-inflamed phenotypes, shared features of an increased angiogenesis score, TGF-β and Wnt-β catenin pathway upregulation and were enriched for BAP1 mutations and FGFR2 fusions.

Conclusion

We identified three spatial immunophenotypes with different overall prognoses in iCCA. Tailored therapies based on the distinct immune evasion mechanisms of the spatial immunophenotypes are needed.

Impact and implications

The contribution of immune cell infiltration in the invasive margin and peritumour areas has been proved. We explored the multiregional immune contexture of 192 patients to identify three spatial immunophenotypes in intrahepatic cholangiocarcinoma (iCCA). By integrating genomic and transcriptomic data, phenotype-specific biological behaviours and potential immune escape mechanisms were analysed. Our findings provide a rationale to develop personalized therapies for iCCA.

Transcription factor glucocorticoid modulatory element-binding protein 1 promotes hepatocellular carcinoma progression by activating Yes-associate protein 1

BACKGROUND

Glucocorticoid modulatory element-binding protein 1 (GMEB1), which has been identified as a transcription factor, is a protein widely expressed in various tissues. Reportedly, the dysregulation of GMEB1 is linked to the genesis and development of multiple cancers.

AIM

To explore GMEB1’s biological functions in hepatocellular carcinoma (HCC) and figuring out the molecular mechanism.

METHODS

GMEB1 expression in HCC tissues was analyzed employing the StarBase database. Immunohistochemical staining, Western blotting and quantitative real-time PCR were conducted to examine GMEB1 and Yes-associate protein 1 (YAP1) expression in HCC cells and tissues. Cell counting kit-8 assay, Transwell assay and flow cytometry were utilized to examine HCC cell proliferation, migration, invasion and apoptosis, respectively. The JASPAR database was employed for predicting the binding site of GMEB1 with YAP1 promoter. Dual-luciferase reporter gene assay and chromatin immunoprecipitation-qPCR were conducted to verify the binding relationship of GMEB1 with YAP1 promoter region.

RESULTS

GMEB1 was up-regulated in HCC cells and tissues, and GMEB1 expression was correlated to the tumor size and TNM stage of HCC patients. GMEB1 overexpression facilitated HCC cell multiplication, migration, and invasion, and suppressed the apoptosis, whereas GMEB1 knockdown had the opposite effects. GMEB1 bound to YAP1 promoter region and positively regulated YAP1 expression in HCC cells.

CONCLUSION

GMEB1 facilitates HCC malignant proliferation and metastasis by promoting the transcription of the YAP1 promoter region.

Overexpressed kinetochore genes are used by cancer cells as genome destabilizers and transformation catalysts

Cancer cells have an altered transcriptome, which contributes to their abnormal behavior. Many tumors have high levels of kinetochore genes, which play important roles in genome stability. This overexpression could be utilized to destabilize cancer cell genomes, however this has not been proven specifically. We investigated the link between kinetochore gene overexpression, chromosomal number variations (CNVs) and genomic instability. Data on RNA expression and CNV from 12 different cancer types were evaluated using information theory. In all cancer types, we looked at the relationship between RNA expression and CNVs. Kinetochore gene expression was found to be substantially linked with CNV levels. In all cancer types, with the exception of thyroid cancer, highly expressed kinetochore genes were enriched in the most dominant cancer-specific co-expression subnetworks characterizing the largest patient subgroups. Except for thyroid cancer, kinetochore inner protein CENPA was among the transcripts most strongly associated with CNV values in all cancer types studied, with significantly higher expression levels in patients with high CNVs than in patients with low CNVs. CENPA function was investigated further in cell models by transfecting genomically stable (HCT116) and unstable (MCF7 and HT29) cancer cell lines using CENPA overexpression vectors. This overexpression increased the number of abnormal cell divisions in the stable cancer cell line HCT116 and, to a lesser extent, in the unstable cell lines MCF7 and HT29. Overexpression improved anchorage-independent growth properties of all cell lines. Our findings suggest that overexpression of kinetochore genes in general, and CENPA in particular, can cause genomic instability and cancer progression.

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.

Cancer-associated fibroblasts potentiate colorectal cancer progression by crosstalk of the IGF2-IGF1R and Hippo-YAP1 signaling pathways

Colorectal cancer (CRC) is one of the most common cancers worldwide. The tumor microenvironment exerts crucial effects in driving CRC progression. Cancer-associated fibroblasts (CAFs) serve as one of the most important tumor microenvironment components promoting CRC progression. This study aimed to elucidate the novel molecular mechanisms of CAF-secreted insulin-like growth factor (IGF) 2 in colorectal carcinogenesis. Our results indicated that IGF2 was a prominent factor upregulated in CAFs compared with normal fibroblasts. CAF-derived conditioned media (CM) promoted tumor growth, migration, and invasion of HCT 116 and DLD-1 cells. IGF1R expression is significantly increased in CRC, serving as a potent receptor in response to IGF2 stimulation and predicting unfavorable outcomes for CRC patients. Apart from the PI3K-AKT pathway, RNA-seq analysis revealed that the YAP1-target signature serves as a prominent downstream effector to mediate the oncogenic signaling of IGF2-IGF1R. By single-cell RNA sequencing (scRNA-seq) and immunohistochemical validation, IGF2 was found to be predominantly secreted by CAFs, whereas IGF1R was expressed mainly by cancer cells. IGF2 triggers the nuclear accumulation of YAP1 and upregulates YAP1 target signatures; however, these effects were abolished by either IGF1R knockdown or inhibition with picropodophyllin (PPP), an IGF1R inhibitor. Using CRC organoid and in vivo studies, we found that cotargeting IGF1R and YAP1 with PPP and verteporfin (VP), a YAP1 inhibitor, enhanced antitumor effects compared with PPP treatment alone. In conclusion, this study revealed a novel molecular mechanism by which CAFs promote CRC progression. The findings highlight the translational potential of the IGF2-IGF1R-YAP1 axis as a prognostic biomarker and therapeutic target for CRC. © 2022 The Pathological Society of Great Britain and Ireland.

Advances in understanding of role and mechanism of Hippo signaling pathway in colorectal cancer

Colorectal cancer (CRC) is one of the most common malignant tumors, and most patients have a poor prognosis. Many studies have shown that the Hippo signaling pathway plays a key role in the occurrence and development of CRC by regulating CRC cell proliferation and apoptosis, tumor invasion and metastasis, autophagy, metabolic reprogramming, drug resistance, and other processes. This article reviews the latest progress in research of the expression of key molecules of the Hippo signaling pathway in CRC as well as the understanding of the mechanism by which this pathway regulates the occurrence and development of CRC.

MiR-22-3p regulates the proliferation, migration and invasion of colorectal cancer cells by directly targeting KDM3A through the Hippo pathway

Colorectal cancer (CRC) has one of the highest incidences and mortality rates of all malignancies worldwide. microRNAs (miRNAs) have been reported to be involved in many biological processes of diseases. MiR-22-3p is considered to be involved in cancer progression, but its role in CRC remains unclear. In this study, we detected that in CRC, the level of miR-22-3p is downregulated. MiR-22-3p has antitumor effects in CRC. miR-22-3p can reduce the proliferative, invasive and migrative capacity of CRC cells. Luciferase reporter analyses confirmed that KDM3A was a target of miR-22-3p, which can directly target the 3'UTR of KDM3A and decrease the expression of KDM3A in CRC cells. Our study also confirmed that KDM3A plays a role as an oncogene in CRC. KDM3A overexpression attenuated the tumor suppressor effects of miR-22-3p in CRC cells, demonstrating that miR-22-3p exerts antitumor effects by targeting KDM3A. Overexpression of miR-22-3p in CRC reduced YAP1 expression, whereas overexpression of KDM3A restored the expression of YAP1. In summary, miR-22-3p might inhibit the progression of CRC by targeting KDM3A to regulate the HIPPO signaling pathway, which may provide an opportunity for the treatment of CRC.

Discovery of a new class of reversible TEA domain transcription factor inhibitors with a novel binding mode

The TEA domain (TEAD) transcription factor forms a transcription co-activation complex with the key downstream effector of the Hippo pathway, YAP/TAZ. TEAD-YAP controls the expression of Hippo-responsive genes involved in cell proliferation, development, and tumorigenesis. Hyperactivation of TEAD-YAP activities is observed in many human cancers and is associated with cancer cell proliferation, survival, and immune evasion. Therefore, targeting the TEAD-YAP complex has emerged as an attractive therapeutic approach. We previously reported that the mammalian TEAD transcription factors (TEAD1-4) possess auto-palmitoylation activities and contain an evolutionarily conserved palmitate-binding pocket (PBP), which allows small-molecule modulation. Since then, several reversible and irreversible inhibitors have been reported by binding to PBP. Here, we report a new class of TEAD inhibitors with a novel binding mode. Representative analog TM2 shows potent inhibition of TEAD auto-palmitoylation both in vitro and in cells. Surprisingly, the co-crystal structure of the human TEAD2 YAP-binding domain (YBD) in complex with TM2 reveals that TM2 adopts an unexpected binding mode by occupying not only the hydrophobic PBP, but also a new side binding pocket formed by hydrophilic residues. RNA-seq analysis shows that TM2 potently and specifically suppresses TEAD-YAP transcriptional activities. Consistently, TM2 exhibits strong antiproliferation effects as a single agent or in combination with a MEK inhibitor in YAP-dependent cancer cells. These findings establish TM2 as a promising small-molecule inhibitor against TEAD-YAP activities and provide new insights for designing novel TEAD inhibitors with enhanced selectivity and potency.

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.

RASAL2 mediated the enhancement of YAP1/TIAM1 signaling promotes malignant phenotypes of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a high incidence of metastasis and dismal prognosis. As a member of Gas-Gap gene, RASAL2 is involved in the hydrolysis of RAS-GTP to RAS-GDP and abnormal expression in human cancers. Here we firstly described the function of RASAL2 on PDAC to enrich the knowledge of RAS family.We interestingly observed that RASAL2 expression was upregulated in PDAC at both mRNA and protein levels, and high expression of RASAL2 predicted a poor prognosis in PDAC patients. Additionally, RASAL2 promoted malignant behaviors of PDAC in vitro and in vivo. To determine the mechanistic roles of RASAL2 signaling and its potential as a therapeutic target in PDAC, we clarified that RASAL2 could accumulate the TIAM1 expression in different level through inhibiting YAP1 phosphorylation, increased TIAM1 mRNA expression and suppressed ubiquitination of TIAM1 protein. In conclusion, RASAL2 enhances YAP1/TIAM1 signaling and promotes PDAC development and progression.

MiR-103a-3p Contributes to the Progression of Colorectal Cancer by Regulating GREM2 Expression

PURPOSE

Our research aimed to investigate the influence of miR-103a-3p on the growth and apoptosis of colorectal cancer (CRC) cells.

MATERIALS AND METHODS

Bioinformatics was employed to analyze differentially expressed microRNAs and predict target genes. qRT-PCR was applied to detect the expression of miR-103a-3p in CRC and normal cells. HCT116 and Caco-2 were chosen, and miR-103a-3p mimics, miR-103a-3p inhibitor, as well as specific siRNAs targeting GREM2, were constructed. We subsequently evaluated alternations in cell proliferation, cell cycle and cell cycle regulators, apoptosis, and related proteins (Bcl-2 and Bax) by CCK-8 testing, Western blotting, luciferase reporter, colony formation, and Annexin V-FITC/PI. Possible binding sites for miR-103a-3p on the 3'UTR of GREM2 were checked with luciferase assay, and the impact of GREM2 on miR-103a-3p activity was also validated with above biological function testing. Additionally, the effect of miR-103a-3p knockdown in CRC cells and the molecular mechanism of miR-103a-3p targeting GREM2 were also studied.

RESULTS

Bioinformatics analysis revealed that miR-103a-3p expression increased remarkably in CRC, and targeted regulatory correlation existed between miR-103a-3p and GREM2. MiR-103a-3p inhibitor significantly impeded proliferative capacity and caused cell cycle arrest, as well as apoptosis, in HCT116 and Caco-2 cells. Consistent with this finding, overexpression of GREM2 showed similar effects to miR-103a-3p inhibition. Moreover, we demonstrated that miR-103a-3p connected target GREM2 and GREM2 knockdown reversed the effects of miR-103a-3p inhibitor on HCT116 and Caco-2 cell proliferation, cell cycle, and apoptosis. Further study showed that miR-103a-3p targeting GREM2 appeared to affect CRC progression via the transforming growth factor-β pathway.

CONCLUSION

MiR-103a-3p could augment CRC progression by targeting GREM2 and that miR-103a-3p/GREM2 could be potential novel targets for CRC therapy.

Metallothionein 2A (MT2A) controls cell proliferation and liver metastasis by controlling the MST1/LATS2/YAP1 signaling pathway in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is one of the three major cancers in the world and is the cancer with the most liver metastasis. The present study aimed to investigate the role of metallothionein 2A (MT2A) in the modulation of CRC cell proliferation and liver metastasis, as well as its molecular mechanisms.

METHODS

The expression profile of metallothionein 2A (MT2A) in colorectal cancer retrieved from TCGA, GEO and Oncomine database. The biological effect of MT2A overexpression was investigated mainly involving cell proliferation and migration in CRC cells as well as growth and metastasis in CRC animal models. To explore the specific mechanism of MT2A metastasis in CRC, transcriptome sequencing was used to compare the overall expression difference between the control group and the MT2A overexpression group.

RESULTS

Metallothionein 2A (MT2A) was downregulated in the tumor tissues of patients with CRC compared to adjacent normal tissues and was related to the tumor M stage of patients. MT2A overexpression inhibited CRC cell proliferation and migration in cells, as well as growth and metastasis in CRC animal models. While knockdown of MT2A had the opposite effect in cells. Western blotting confirmed that MT2A overexpression promoted the phosphorylation of MST1, LAST2 and YAP1, thereby inhibiting the Hippo signaling pathway. Additionally, specific inhibitors of MST1/2 inhibited MT2A overexpression-mediated phosphorylation and relieved the inhibition of the Hippo signaling pathway, thus promoting cell proliferation. Immunohistochemistry in subcutaneous grafts and liver metastases further confirmed this result.

CONCLUSIONS

Our results suggested that MT2A is involved in CRC growth and liver metastasis. Therefore, MT2A and MST1 may be potential therapeutic targets for patients with CRC, especially those with liver metastases.

Helicobacter pylori-induced RASAL2 Through Activation of Nuclear Factor-κB Promotes Gastric Tumorigenesis via β-catenin Signaling Axis

BACKGROUND & AIMS

Helicobacter pylori infection is the predominant risk factor for gastric cancer. RAS protein activator like 2 (RASAL2) is considered a double-edged sword in carcinogenesis. Herein, we investigated the role of RASAL2 in response to H pylori infection and gastric tumorigenesis.

METHODS

Bioinformatics analyses of local and public databases were applied to analyze RASAL2 expression, signaling pathways, and clinical significance. In vitro cell culture, spheroids, patient-derived organoids, and in vivo mouse models were used. Molecular assays included chromatin immunoprecipitation, co-immunoprecipitation, Western blotting, quantitative polymerase chain reaction, and immunocyto/histochemistry.

RESULTS

H pylori infection induced RASAL2 expression via a nuclear factor-κB (NF-κB)-dependent mechanism whereby NF-κB was directly bound to the RASAL2 promoter activating its transcription. By gene silencing and ectopic overexpression, we found that RASAL2 upregulated β-catenin transcriptional activity. RASAL2 inhibited protein phosphatase 2A activity through direct binding with subsequent activation of the AKT/β-catenin signaling axis. Functionally, RASAL2 silencing decreased nuclear β-catenin levels and impaired tumor spheroids and organoids formation. Furthermore, the depletion of RASAL2 impaired tumor growth in gastric tumor xenograft mouse models. Clinicopathological analysis indicated that abnormal overexpression of RASAL2 correlated with poor prognosis and chemoresistance in human gastric tumors.

CONCLUSIONS

These studies uncovered a novel signaling axis of NF-κB/RASAL2/β-catenin, providing a novel link between infection, inflammation and gastric tumorigenesis.

Inhibition of Ras protein activator like 2 produces antitumor effects in gastric cancer via the suppression of YAP1 activation

Ras protein activator like 2 (RASAL2) has a cancer-related function, but plays inconsistent roles in different malignancies. This project was designed to determine the role of RASAL2 in carcinogenesis in gastric cancer. The Cancer Genome Atlas data revealed high levels of RASAL2 in gastric cancer tissue, which was confirmed in clinical specimens of gastric cancer via real-time quantitative PCR and western blotting assays. High RASAL2 was correlated with a reduced survival rate in gastric cancer patients. In gastric cancer cell lines, the silencing of RASAL2 restrained cellular proliferation, invasion and epithelial-to-mesenchymal transition, while enhancing chemosensitivity to cisplatin. Mechanistically, the silencing of RASAL2 was found to inhibit the activation of Yes-associated protein 1 (YAP1), a pro-oncogenic protein in gastric cancer, and decrease the expression of YAP1 target genes. The re-expression of constitutively active YAP1 substantially reversed RASAL2-silencing-produced antitumor effects. Moreover, treatment with YAP1 inhibitors could diminish RASAL2-overexpression-evoked oncogenic effects in gastric cancer cells. Additionally, gastric cancer cells with RASAL2 silencing exhibited a reduced ability to form xenograft tumors in nude mice. Collectively, our data demonstrate that the silencing of RASAL2 has noteworthy antitumor effects in gastric cancer cells via the suppression of YAP1 activation. This project underscores a vital role of the RASAL2/YAP1 axis in gastric progression and indicates that targeting this oncogenic axis may be applied as a potential therapeutic option for gastric cancer.

Identification of a Schistosoma japonicum MicroRNA That Suppresses Hepatoma Cell Growth and Migration by Targeting Host FZD4 Gene

Previous studies have demonstrated miRNAs derived from plants and parasites can modulate mammalian gene expression and cell phenotype in a cross-kingdom manner, leading to occurrence of diseases or strengthening resistance of host to diseases such as cancer. In this study, we identified a schistosome miRNA (named Sja-miR-71a) through screening of 57 Schistosoma japonicum miRNAs that exerts antitumor activity in vitro and in vivo models. We demonstrated presence of this parasite miRNA in liver cells during infection. We showed that Sja-miR-71a arrested cell cycle at G0/G1 phase of hepatoma cell lines and inhibited cell proliferation in vitro. The HepG2 transfected with Sja-miR-71a mimics displayed significant reduction of migration and colony formation. Further, growth of the tumor cells transfected with the Sja-miR-71a mimics was obviously suppressed in a xenograft mouse model. Mechanically, we found the antitumor activity of Sja-miR-71a was through targeting a host gene encoding Frizzled Class Receptor 4 (FZD4), as FZD4 small interfering RNAs (siRNAs) generated a similar inhibitory effect on the tumor. These data indicated that Sja-miR-71a is a tumor suppressor miRNA and suggested this parasite-derived miRNA as a potential therapeutic target for cancer.

RAS protein activator like 2 promotes the proliferation and migration of pulmonary artery smooth muscle cell through AKT/mammalian target of Rapamycin complex 1 pathway in pulmonary hypertension

RAS protein activator like 2 (Rasal2) exerts pro-proliferative effect in several types of cells. However, whether Rasal2 is involved in the regulation of pulmonary artery smooth muscle cell (PASMC) remains unclear. In the current study, we explored the role of Rasal2 in proliferation and migration of PASMC during the development of pulmonary arterial hypertension (PAH). We found that the protein level of Rasal2 was increased in both pulmonary arteries of chronic hypoxia-induced pulmonary hypertension (CH-PH) mice and hypoxia-challenged PASMC. Overexpression of Rasal2 caused enhanced proliferation and migration of PASMC after hypoxia exposure. Mechanistically, we found elevated phosphorylation of AKT and two downstream effectors of mammalian target of Rapamycin complex 1 (mTORC1), S6 and 4E-Binding Protein 1 (4EBP1) after Rasal2 overexpression in hypoxia-challenged PASMC. Inactivation of mTORC1 abolished Rasal2-mediated enhancement of proliferation and migration of PASMC. Furthermore, we also demonstrated that AKT might act downstream of Rasal2 to enhance the activity of mTORC1. Once AKT was inactivated by MK-2206 application, overexpression of Rasal2 failed to further increase the phosphorylation level of S6 and 4EBP1. Finally, inhibition of AKT also blocked Rasal2-induced proliferation and migration in hypoxia-challenged PASMC. In conclusion, Rasal2 promotes the proliferation and migration of PASMC during the development of PAH via AKT/mTORC1 pathway.

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.

Siglec-15 Is an Immune Suppressor and Potential Target for Immunotherapy in the Pre-Metastatic Lymph Node of Colorectal Cancer

Lymph node metastasis indicates a poor prognosis in colorectal cancer. To better understand the underlying mechanisms of lymph node metastasis, we analyzed transcriptome characteristics of the pre-metastatic lymph node, a putative microenvironment favorable for the seeding and proliferation of cancer cells. Thus, we tried to compare and elucidate the transcriptional and immune characteristics of sentinel lymph nodes (SNs) with matched non-sentinel lymph nodes (NSNs) in colorectal cancer patients. In this study, a total of 38 pairs of SNs and NSNs were collected, in which 26 pairs of non-metastatic lymph nodes were subjected to RNA-seq and bioinformatics analysis for the gene expression profiles. There were 16 differentially expressed genes between SNs and NSNs being identified, including 9 upregulated and 7 downregulated genes in SN. Gene Ontology (GO) classification analysis revealed that the differentially expressed genes were mainly involved in leukocyte differentiation, chemokine secretion, and immune system regulation. In the meantime, gene set enrichment analysis (GSEA) showed that immune-related signaling pathways, such as transforming growth factor beta (TGF-β) signaling and tumor necrosis factor alpha (TNF-α)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling, were enriched in NSN, while cell proliferation–related signaling pathways were enriched in SN, including MYC signaling and G2M checkpoint signaling. We further identified SIGLEC15 as a top upregulated gene in SN. However, RNAscope assay showed that SIGLEC15 was not largely co-expressed with M2 macrophage marker CD163. We then selected eight pairs of lymph nodes for further cytological studies. Flow cytometry analysis revealed that Siglec-15 was expressed on all myeloid cell subsets. The relative expression of SEGLEC15 (SN/NSN) was correlated with the microsatellite instability (MSI) status in colorectal cancer patients. Further studies found that small interfering ribonucleic acid (siRNA)-mediated silencing of SLGLEC15 can enhance the anti-tumor function of T cells, as indicated by cytokine release analysis. In conclusion, we presented here a first report on the gene expression profiling of the pre-metastatic lymph node in colorectal cancer. The findings in this study suggest that SIGLEC15 plays an important role in SN immunosuppression. SEGLEC15 silencing could be a therapeutic strategy for restoring T cell function in tumor SNs.

CHRAC1 promotes human lung cancer growth through regulating YAP transcriptional activity

ATP-dependent chromatin remodeling complexes regulate chromatin structure and play important roles in gene expression, differentiation, development and cancer progression. Dysregulation in the subunits of the complexes often has been found in different cancers, but how they influence cancer initiation and progression is not fully understood. Here we show that Chromatin Accessibility Complex Subunit 1 (CHRAC1), the accessory subunit of chromatin remodeling complex, is highly expressed in lung cancer tissues, which correlates with poor prognosis in lung cancer patients. CHRAC1 overexpression promotes lung cancer cell proliferation and migration in vitro and tumor growth in genetically engineered Kras G12D.LSL lung adenocarcinoma mouse model. Consistent with this, CHRAC1 silencing inhibits cell proliferation and migration in lung cancer cells and suppresses tumor growth in xenograft mouse model. Further, CHRAC1 binds to the transcription co-activator Yes-associated protein (YAP), enhances the transcription of downstream target oncogenes in Hippo pathway and thus promotes the tumor growth. Together, our study defines a critical role of CHRAC1 in promoting YAP transcriptional activity and lung cancer tumorigenesis, which makes it a potential target for lung cancer.

Signature identification of relapse-related overall survival of early lung adenocarcinoma after radical surgery

Background

The widespread use of low-dose chest CT screening has improved the detection of early lung adenocarcinoma. Radical surgery is the best treatment strategy for patients with early lung adenocarcinoma; however, some patients present with postoperative recurrence and poor prognosis. Through this study, we hope to establish a model that can identify patients that are prone to recurrence and have poor prognosis after surgery for early lung adenocarcinoma.

Materials and Methods

We screened prognostic and relapse-related genes using The Cancer Genome Atlas (TCGA) database and the GSE50081 dataset from the Gene Expression Omnibus (GEO) database. The GSE30219 dataset was used to further screen target genes and construct a risk prognosis signature. Time-dependent ROC analysis, calibration degree analysis, and DCA were used to evaluate the reliability of the model. We validated the TCGA dataset, GSE50081, and GSE30219 internally. External validation was conducted in the GSE31210 dataset.

Results

A novel four-gene signature (INPP5B, FOSL2, CDCA3, RASAL2) was established to predict relapse-related survival outcomes in patients with early lung adenocarcinoma after surgery. The discovery of these genes may reveal the molecular mechanism of recurrence and poor prognosis of early lung adenocarcinoma. In addition, ROC analysis, calibration analysis and DCA were used to verify the genetic signature internally and externally. Our results showed that our gene signature had a good predictive ability for recurrence and prognosis.

Conclusions

We established a four-gene signature and predictive model to predict the recurrence and corresponding survival rates in patients with early lung adenocarcinoma after surgery. These may be helpful for reforumulating post-operative consolidation treatment strategies.

Yes-associated protein expression is associated with poor prognosis in patients with colorectal cancer

Colorectal cancer (CRC) is the third leading cause of cancer-related death worldwide. The aim of the present study was to investigate the expression of yes-associated protein (YAP) in CRC tissues, and to determine the relationship between the expression levels of YAP and the clinicopathological characteristics and prognosis of patients with CRC. Bioinformatics analysis was conducted to examine the expression of YAP and its correlation with clinicopathological characteristics and key genes, using functional enrichment analysis. Immunohistochemistry was used to detect YAP expression in 181 CRC tissue samples and 30 normal colorectal mucosa samples. Western blotting and reverse transcription-quantitative PCR were performed to detect the expression of YAP and β-catenin in CRC cells, and cellular proliferation was assessed using a Cell Counting Kit-8 assay. Finally, apoptosis was analyzed using flow cytometry. Immunohistochemical staining indicated that the positive expression rate of YAP in CRC tissues was 73.5%, which was significantly higher than that in normal colorectal mucosa samples. The expression of YAP in CRC was associated with histological differentiation, lymph node metastasis and Duke's stage. However, no significant associations were observed between YAP expression and age, sex and T stage. Downregulation of YAP promoted the proliferation and the inhibited apoptosis of CRC cells, and YAP expression was positively correlated with that of β-catenin in both CRC tissues and cells. Furthermore, YAP expression was upregulated in CRC tissues, which was correlated with tumor progression and prognosis. Therefore, YAP expression may be used as an independent predictor of poor prognosis in patients with CRC, and the underling molecular mechanism may be associated with the combined effect of Hippo and Wnt/β-catenin signaling.

Low Expression of Rasal2 Promotes Non-small Cell Lung Cancer Metastasis through Ras/ERK Pathway

The RAS protein activator like 2 (Rasal2) has been reported to be a tumor suppressor in variety of cancers; while an oncogenic protein in ovarian cancer and triple negative breast cancer (TNBC). However, the exact role of Rasal2 in non-small cell lung cancer (NSCLC) is lacking. This study aimed to investigate the role of Rasal2 in NSCLC and the underlying mechanisms. Rasal2 expression level was measured in NSCLC tissue and cells by using quantitative (q)-PCR and immunoblotting analysis. The clinical implication of Rasal2 in NSCLC patients was also analyzed. The function role of Rasal2 in NSCLC cells were measured by small interfering RNA (si-RNA), immunostaining, transwell assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Low Rasal2 expression level was observed in human NSCLC tissue and cell lines and significantly related to tumor thickness, ulceration and TNM staging in NSCLC patients. Rasal2 knockdown significantly increased NSCLC cell invasion and migration. Mechanistically, we showed that Rasal2 knockdown significantly increased the phosphorylation level of extracellular signal-regulated kinase (ERK)/Raf1/mitogen-activated protein extracellular kinase (MEK) thus activated Ras/ERK signal pathway. Thus, our data showed that Rasal2 is downregulated in NSCLC cells and act as an epithelial-mesenchymal transition (EMT) and metastasis suppressor through the Ras/ERK pathway. Rasal2 may be a prognostic biomarker for NSCLC in the future.

RP11-51O6.1 sponges miR-206 to accelerate colorectal cancer carcinogenesis and metastasis through upregulating YAP1

Long non-coding RNAs (lncRNAs) have been characterized by playing a crucial role in tumorigenesis. However, the detail biological function and clinical importance of lncRNAs in colorectal cancer (CRC) are unclear and have attracted different levels of in-depth research. In this context, we explored the differentially expressed profiles of lncRNAs in six CRC tissues and three adjacent non-tumor tissues from RNA-sequencing (RNA-seq) study and noted a lncRNA, RP11-51O6.1, which is markedly overexpressed in CRC tissues, particularly in aggressive cases. Impressively, an elevated RP11-51O6.1 level was highly correlated with poor prognosis in clinical patients. Functional analyses revealed that RP11-51O6.1 could promote cell proliferation in vitro and in vivo. Furthermore, we reported that RP11-51O6.1 enhances cell migration and invasion in vitro. Mechanistic studies (Bioinformatics binding site analyses, the Luciferase reporter, Ago2 immunoprecipitation, the RNA pull-down, immunofluorescence colocalization, rescued assays and western blotting) implicated that RP11-51O6.1 could regulate YAP1 expression by competitively sponging miR-206 and blocking its activity in promoting CRC progression. Conclusively, our findings identify a novel RP11-51O6.1/miR-206/YAP1 regulatory axis that participates in CRC progression and development, suggesting RP11-51O6.1 is an exploitable biomarker and appealing therapeutic target in treating CRC.

SEPT6 drives hepatocellular carcinoma cell proliferation, migration and invasion via the Hippo/YAP signaling pathway

Septin 6 (SEPT6) is a member of the GTP-binding protein family that is highly conserved in eukaryotes and regulates various biological functions, including filament dynamics, cytokinesis and cell migration. However, the functional importance of SEPT6 in hepatocellular carcinoma (HCC) is not completely understood. The present study aimed to investigate the expression levels and roles of SEPT6 in HCC, as well as the underlying mechanisms. The reverse transcription quantitative PCR, western blotting and immunohistochemistry staining results demonstrated that SEPT6 expression was significantly elevated in HCC tissues compared with corresponding adjacent non-tumor tissues, which indicated that SEPT6 expression may serve as a marker of poor prognosis for HCC. By performing plasmid transfection and G418 treatment, stable SEPT6-knockdown and SEPT6-overexpression cell lines were established. The Cell Counting Kit-8, flow cytometry and Transwell assay results demonstrated that SEPT6 overexpression significantly increased HCC cell proliferation, cell cycle transition, migration and invasion compared with the Vector group, whereas SEPT6 knockdown displayed significant suppressive effects on HCC cell lines in vitro compared with the control group. Mechanistically, SEPT6 might facilitate F-actin formation, which induced large tumor suppressor kinase 1 dephosphorylation, inhibited Hippo signaling, upregulated yes-associated protein (YAP) expression and nuclear translocation, and upregulated cyclin D1 and matrix metallopeptidase 2 (MMP2) expression. Furthermore, YAP overexpression significantly reversed SEPT6 knockdown-induced inhibitory effects on HCC, whereas YAP knockdown significantly inhibited the oncogenic effect of SEPT6 overexpression on HCC. Collectively, the present study demonstrated that SEPT6 may promote HCC progression by enhancing YAP activation, suggesting that targeting SEPT6 may serve as a novel therapeutic strategy for HCC.

RNA N6-Methyladenosine Methyltransferase METTL3 Facilitates Colorectal Cancer by Activating the m6A-GLUT1-mTORC1 Axis and Is a Therapeutic Target

BACKGROUND & AIMS

RNA N6-methyladenosine (m6A) modification has recently emerged as a new regulatory mechanism in cancer progression. We aimed to explore the role of the m6A regulatory enzyme METTL3 in colorectal cancer (CRC) pathogenesis and its potential as a therapeutic target.

METHODS

The expression and clinical implication of METTL3 were investigated in multiple human CRC cohorts. The underlying mechanisms of METTL3 in CRC were investigated by integrative m6A sequencing, RNA sequencing, and ribosome profiling analyses. The efficacy of targeting METTL3 in CRC treatment was elucidated in CRC cell lines, patient-derived CRC organoids, and Mettl3-knockout mouse models.

RESULTS

Using targeted clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 dropout screening, we identified METTL3 as the top essential m6A regulatory enzyme in CRC. METTL3 was overexpressed in 62.2% (79/127) and 88.0% (44/50) of primary CRCs from 2 independent cohorts. High METTL3 expression predicted poor survival in patients with CRC (n = 374, P < .01). Functionally, silencing METTL3 suppressed tumorigenesis in CRC cells, human-derived primary CRC organoids, and Mettl3-knockout mouse models. We discovered the novel functional m6A methyltransferase domain of METTL3 in CRC cells by domain-focused CRISPR screening and mutagenesis assays. Mechanistically, METTL3 directly induced the m6A-GLUT1-mTORC1 axis as identified by integrated m6A sequencing, RNA sequencing, ribosome sequencing, and functional validation. METTL3 induced GLUT1 translation in an m6A-dependent manner, which subsequently promoted glucose uptake and lactate production, leading to the activation of mTORC1 signaling and CRC development. Furthermore, inhibition of mTORC1 potentiated the anticancer effect of METTL3 silencing in CRC patient-derived organoids and METTL3 transgenic mouse models.

CONCLUSIONS

METTL3 promotes CRC by activating the m6A-GLUT1-mTORC1 axis. METTL3 is a promising therapeutic target for the treatment of CRC.

Novel Resistance Mechanisms to Osimertinib Analysed by Whole-Exome Sequencing in Non-Small Cell Lung Cancer

Purpose

Molecular-based targeted therapy has improved life expectancy for advanced non-small cell lung cancer (NSCLC). However, it does not have to be inevitable that patients receiving third-generation EGFR-TKIs become drug resistant. EGFR C797S and MET amplification are common mechanisms of osimertinib. However, a large part of these potential drug mechanisms remains unknown, and further research is needed.

Methods

Tumour and blood samples from forty advanced NSCLC patients were identified as acquired drug resistant to osimertinib. The NGS panel was applied to detect EGFR C797S and MET amplification in tumour tissues or plasma samples. Whole-exome sequencing was conducted in five pairs of tumour tissues obtained before osimertinib administration and after osimertinib resistance in patients without C797S/cMET amplification.

Results

The overall C797S mutation rate was 20%, and MET amplification was detected in six out of sixteen C797S-negative samples. PDGFRA in the PI3K-AKT-mTOR signalling pathway, RASAL2, RIN3 and SOS2 in the RAS-Raf-ERK signalling pathway, PTK2 in the ERBB signalling pathway and ABCC1 and ABCB5 in the ABC membrane pump system were identified as candidate crucial genes of drug resistance to osimertinib.

Conclusion

EGFR C797S mutation and MET amplification are leading mechanisms for osimertinib resistance in lung cancer. The crucial potential mutated genes defined in our present study may need further validation in a considerable number of lung cancer patients.

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.

Long non‑coding RNA ASAP1‑IT1 suppresses ovarian cancer progression by regulating Hippo/YAP signaling

Long non‑coding RNAs (lncRNAs) are a class of non‑protein coding transcripts that are involved in the regulation of gene expression in mammalian cells. Transcriptional co‑activator Yes associated protein 1 (YAP1) plays a key role in the progression of ovarian cancer. However, the regulation of Hippo/YAP signaling in ovarian cancer remains elusive. In the present study, the expression levels of lncRNA ASAP1‑IT1 were investigated. The analysis indicated that lncRNA ASAP1‑IT1 expression was downregulated in ovarian tumor samples and ovarian cancer cells. The overexpression of ASAP1‑IT1 inhibited ovarian cancer cell proliferation and induced cell apoptosis. Bioinformatics analysis predicted that miR‑2278, a previously reported upregulated miRNA in ovarian tumors, may bind to ASAP1‑IT1. Dual luciferase assay confirmed the direct regulatory association between ASAP1‑IT1 and miR‑2278. In addition, the data demonstrated that large tumor suppressor 2 (LATS2) was a target gene of miR‑2278, whose expression was upregulated by ASAP1‑IT1 in ovarian cancer cells. By regulating the expression of LATS2, ASAP1‑IT1 induced the downregulation of YAP1 expression in ovarian cancer cells. Moreover, the silencing of LATS2 attenuated the inhibition of cell proliferation and the apoptosis induced by ASAP1‑IT1 overexpression in ovarian cancer cells. The association among the expression levels of ASAP1‑IT1, miR‑2278 and LATS2 was observed in specimens obtained from patients with ovarian cancer. Taken together, the data presented herein demonstrate that ASAP1‑IT1 functions as a potential tumor suppressor lncRNA by upregulating LATS2 expression in ovarian cancer.

Systematic analysis using a bioinformatics strategy identifies SFTA1P and LINC00519 as potential prognostic biomarkers for lung squamous cell carcinoma

Lung cancer has high incidence and mortality rates, in which lung squamous cell carcinoma (LUSC) is a primary type of non-small cell lung carcinoma (NSCLC). The aim of our study was to discover long non-coding RNAs (lncRNAs) associated with diagnose and prognosis for LUSC. RNA sequencing data obtained from LUSC samples were extracted from The Cancer Genome Atlas database (TCGA). Two prognosis-associated lncRNAs (including SFTA1P and LINC00519) were selected from LUSC samples, and the expression levels were also verified to be associated abnormal in LUSC clinical samples. Our findings demonstrate that lncRNAs SFTA1P and LINC00519 exert important functions in human LUSC and may serve as new targets for LUSC diagnosis and therapy.

Hypermethylation of LATS2 Promoter and Its Prognostic Value in IDH-Mutated Low-Grade Gliomas

Mutations in the enzyme isocitrate dehydrogenase 1/2 (IDH1/2) are the most common somatic mutations in low-grade glioma (LGG). The Hippo signaling pathway is known to play a key role in organ size control, and its dysregulation is involved in the development of diverse cancers. Large tumor suppressor 1/2 (LATS1/2) are core Hippo pathway components that phosphorylate and inactivate Yes-associated protein (YAP), a transcriptional co-activator that regulates expression of genes involved in tumorigenesis. A recent report from The Cancer Genome Atlas (TCGA) has highlighted a frequent hypermethylation of LATS2 in IDH-mutant LGG. However, it is unclear if LATS2 hypermethylation is associated with YAP activation and prognosis of LGG patients. Here, we performed a network analysis of the status of the Hippo pathway in IDH-mutant LGG samples and determined its association with cancer prognosis. Combining TCGA data with our biochemical assays, we found hypermethylation of LATS2 promoter in IDH-mutant LGG. LATS2 hypermethylation, however, did not translate into YAP activation but highly correlated with IDH mutation. LATS2 hypermethylation may thus serve as an alternative for IDH mutation in diagnosis and a favorable prognostic factor for LGG patients.

Verteporfin Promotes the Apoptosis and Inhibits the Proliferation, Migration, and Invasion of Cervical Cancer Cells by Downregulating SULT2B1 Expression

Background

Cervical cancer threatens women’s health worldwide. Verteporfin (VP), a small-molecule YAP1 inhibitor, inhibits cancer cell growth. This study investigated whether VP could inhibit the proliferation and promote the apoptosis of cervical cancer cells by decreasing SULT2B1 expression.

Material/Methods

Normal and cancerous cervical cell proliferation after VP treatment was detected by CCK-8 assay. HeLa cell migration, invasion, and apoptosis after VP treatment and transfection were analyzed by wound healing assay, transwell assay, and TUNEL assay, respectively. The expression of related proteins was determined by western blot analysis. Western blot and RT-qPCR analysis detected mRNA and protein expression of SULT2B1.

Results

Different VP concentrations (0.5, 1, 2, and 5 μM) inhibited the viability of HeLa cells and had no obvious effect on H8 cells. Therefore, 5 μM VP was selected for subsequent experiments. VP inhibited the proliferation, migration, and invasion of HeLa cells and promoted their apoptosis. Bcl-2 expression decreased, and expression of Bax, caspase-3, and caspase-9 in VP-treated HeLa cells increased. SULT2B1 expression increased in cervical cancer cells compared with normal cervical cells. Furthermore, SULT2B1 expression increased in HeLa cells and VP suppressed SULT2B1 expression. SULT2B1 overexpression reduced the inhibiting effect of VP on the proliferation, migration, and apoptosis of HeLa cells, and reduced VP effect on apoptosis of HeLa cells. SULT2B1 overexpression upregulated the Bcl-2 expression and downregulated the expression of Bax, caspase-3, and caspase-9 in VP-treated HeLa cells.

Conclusions

VP inhibited the proliferation, migration, and invasion and promoted apoptosis of cervical cancer cells by decreasing SULT2B1 expression.

LASP1 induces colorectal cancer proliferation and invasiveness through Hippo signaling and Nanog mediated EMT

The role of LIM and SH3 protein 1 (LASP1) in colorectal cancer (CRC) has been described in multiple studies, however, the underlying molecular mechanisms remained inclusive. In the present study, we performed immunohistochemistry (IHC) staining for LASP1 and found that LASP1 expression was higher in CRC tissue of advanced stage. Over-expressed (OE) LASP1 promoted proliferation, tumorigenesis and migration of CRC cell lines SW480 and SW620. Using the TCGA database, we identified Yes-associated protein (YAP1) was positively correlated with LASP1 expression in CRC patients. Introducing a novel YAP1 inhibitor CA3, we found that CA3 treatment inhibited LAPS1 OE SW480 and SW620 cells proliferation, colony number formation, invasion and migration. Further mechanistic experiments showed that Nanog, a stem cell marker, was up-regulated in LASP1 OE cells but suppressed by CA3 treatment. Chromatin immunoprecipitation (CHIP) and luciferase reporter assay revealed that YAP1 can directly target the promoter region of Nanog and enhance its activity. LASP1 accelerated CRC migration through targeting YAP1-mediated vimentin and E-cadherin expression. Finally, by developing murine CRC model, we found the primary tumor size was almost abolished and the survival rate was greatly improved by chemotherapy and CA3 combined treatment compared with negative control or chemotherapy treated alone. Collectively, our findings demonstrated that LASP1 could induce CRC tumor cells proliferation and migration through activating hippo signaling pathway component YAP1 and further enhancing Nanog expression.

Genetic variants in Hippo signalling pathway-related genes affect the risk of colorectal cancer

The Hippo signalling pathway plays a crucial role in carcinogenesis. Therefore, we hypothesized that genetic variants in genes related to this pathway are associated with the colorectal cancer risk. A case-control study including 1150 patients and 1342 controls was performed to assess the association of genetic variants of genes involved in the Hippo signalling pathway with the risk of colorectal cancer. The results were corrected for multiple comparisons using the false discovery rate (FDR). We used a regression model to determine the effects of single-nucleotide polymorphisms (SNPs) on the survival of patients with colorectal cancer in The Cancer Genome Atlas (TCGA) datasets. An expression quantitative trait loci (eQTL) analysis was performed using TCGA datasets and the Genotype-Tissue Expression (GTEx) project. Gene Expression Omnibus (GEO) datasets were used to provide additional data on the expression of genes in colorectal cancer. The SCRIB rs13251492 G allele was associated with a significantly decreased risk of colorectal cancer (odds ratio (OR) = 0.79, 95% confidence interval (CI) = 0.70-0.89, P = 7.76 × 10^-5, P_(FDR) = 6.98 × 10^-4). Patients with the rs13251492 AG/GG allele experienced a longer recurrence-free survival (RFS) time (hazard ratio (HR) = 0.64, 95% CI = 0.42-0.99, P = 0.049) than patients with the rs13251492 A allele. The eQTL analysis revealed a significant association between rs13251492 and the expression of the SCRIB mRNA in colorectal tumors. Dual-luciferase reporter assays in DLD-1 and HCT116 cells revealed a lower enhancer activity of the rs13251492 G allele than the A allele. In addition, the SCRIB mRNA was expressed at markedly higher levels in colorectal cancer tissues than in normal tissues. Therefore, we identified the SCRIB rs13251492 variant as a novel colorectal cancer susceptibility locus and provided evidence of its functional relevance.

Livin promotes tumor progression through YAP activation in ovarian cancer

Ovarian cancer is a gynecological malignant tumor with a high morbidity. Livin is a novel member of the inhibitor of apoptosis protein family, which is expressed in various malignant tumors and is suggested to be a poor prognostic factor. However, the prognostic significance of Livin and the molecular mechanisms by which Livin promotes ovarian cancer progression are poorly understood. In this study, the upregulation of Livin was confirmed both in primary specimens from ovarian cancer patients and in ovarian cancer cell lines compared to normal controls in vitro. Overexpression of specific Livin transcripts promoted cell growth and migration in vitro, while knockdown of Livin expression suppressed these cellular processes. These effects of the Livin gene were also demonstrated in a xenograft mouse model. Mechanistic studies further revealed that Livin promotes the proliferation and invasion of ovarian cancer cells by activating the transcriptional coactivator YAP, a critical component of the Hippo signaling pathway. Furthermore, we revealed that inhibition of YAP by short-hairpin RNA prevents the growth and invasion of ovarian cancer cells in vivo and in vitro. Therefore, Livin may be a potential novel therapeutic target for the treatment of ovarian cancer.

The Role of microRNAs in Epithelial Ovarian Cancer Metastasis

Epithelial ovarian cancer (EOC) is the deadliest gynecological cancer, and the major cause of death is mainly attributed to metastasis. MicroRNAs (miRNAs) are a group of small non-coding RNAs that exert important regulatory functions in many biological processes through their effects on regulating gene expression. In most cases, miRNAs interact with the 3′ UTRs of target mRNAs to induce their degradation and suppress their translation. Aberrant expression of miRNAs has been detected in EOC tumors and/or the biological fluids of EOC patients. Such dysregulation occurs as the result of alterations in DNA copy numbers, epigenetic regulation, and miRNA biogenesis. Many studies have demonstrated that miRNAs can promote or suppress events related to EOC metastasis, such as cell migration, invasion, epithelial-to-mesenchymal transition, and interaction with the tumor microenvironment. In this review, we provide a brief overview of miRNA biogenesis and highlight some key events and regulations related to EOC metastasis. We summarize current knowledge on how miRNAs are dysregulated, focusing on those that have been reported to regulate metastasis. Furthermore, we discuss the role of miRNAs in promoting and inhibiting EOC metastasis. Finally, we point out some limitations of current findings and suggest future research directions in the field.

Targeting Colorectal Cancer Stem Cells as an Effective Treatment for Colorectal Cancer

As one of the common cancers that threaten human life, the recurrence and metastasis of colorectal cancer seriously affect the prognosis of patients. Although new drugs and comprehensive treatments have been adopted, the current treatment effect on this tumor, especially in advanced colorectal cancer, is still not satisfactory. More and more evidence shows that tumors are likely to be a stem cell disease. In recent years, the rise of cancer stem cell theory has provided a new way for cancer treatment. Studies have found that a small number of special cells in colorectal cancer tissues that induce tumorigenesis, proliferation, and promote tumor migration and metastasis, namely, colorectal cancer stem cells. Colorectal cancer stem cells are defined with a group of cell-surface markers, such as CD44, CD133, CD24, epithelial cell adhesion factor molecule, LGR5, and acetaldehyde dehydrogenase. They are highly tumorigenic, aggressive, and chemoresistant and thus are critical in the metastasis and recurrence of colorectal cancer. Therefore, targeting colorectal cancer stem cells may become an important research direction for the future cure of colorectal cancer.

The prognostic value of six survival-related genes in bladder cancer

This study was conducted to identify genes that are differentially expressed in paracancerous tissue and to determine the potential predictive value of selected gene panel. Gene transcriptome data of bladder tissue was downloaded from UCSC Xena browser and NCBI GEO repository, including GTEx (the Genotype-Tissue Expression project) data, TCGA (The Cancer Genome Atlas) data, and GEO (Gene Expression Omnibus) data. Differentially Expressed Genes (DEGs) analysis was performed to identify tumor-DEGs candidate genes, using the intersection of tumor-paracancerous DEGs genes and paracancerous-normal DEGs genes. The survival-related genes were screened by Kaplan-Meier (KM) survival analysis and univariable Cox regression with the cutoff criteria of KM < 0.05 and cox p-value < 0.05. The risk model was developed using Lasso regression. The clinical data were analyzed by univariate and multivariate Cox regression analysis. Gene Ontology (GO) and KEGG enrichment analysis were performed in the DEGs genes between the high-risk and low-risk subgroups. We identified six survival-related genes, EMP1, TPM1, NRP2, FGFR1, CAVIN1, and LATS2, found in the DEG analyses of both, tumor-paracancerous and paracancerous-normal differentially expressed data sets. Then, the patients were classified into two clusters, which can be distinguished by specific clinical characteristics. A three-gene risk prediction model (EMP1, FGFR1, and CAVIN1) was constructed in patients within cluster 1. The model was applied to categorize cluster 1 patients into high-risk and low-risk subgroups. The prognostic risk score was considered as an independent prognostic factor. The six identified survival-related genes can be used in molecular characterization of a specific subtype of bladder cancer. This subtype had distinct clinical features of T (topography), N (lymph node), stage, grade, and survival status, compared to the other subtype of bladder cancer. Among the six identified survival-related genes, three-genes, EMP1, FGFR1, and CAVIN1, were identified as potential independent prognostic markers for the specific bladder cancer subtype with clinical features described.

Long noncoding RNA NEAT1 suppresses hepatocyte proliferation in fulminant hepatic failure through increased recruitment of EZH2 to the LATS2 promoter region and promotion of H3K27me3 methylation

Fulminant hepatic failure (FHF) refers to the rapid development of severe acute liver injury with impaired synthetic function and encephalopathy in people with normal liver or well-compensated liver disease. This study aimed to investigate the function of long noncoding RNA (lncRNA) nuclear-enriched abundant transcript 1 (NEAT1) on the proliferation and apoptosis of hepatocytes in FHF. Our results revealed that lncRNA NEAT1 was upregulated in cell and animal models of FHF induced by D-galactosamine (D-GalN)/lipopolysaccharide (LPS). Overexpression of lncRNA NEAT1 resulted in elevated hepatocyte apoptosis and impaired large tumor-suppressor kinase 2 (LATS2) expression and proliferation. Functional analysis revealed that knockdown of lncRNA NEAT1 inhibited hepatocyte apoptosis and induced proliferation both in vitro and in vivo. RNA immunoprecipitation and chromatin immunoprecipitation assays demonstrated that lncRNA NEAT1 recruited enhancer of zeste homolog 2 (EZH2) to the LATS2 promoter and repressed LATS2 expression. Furthermore, ectopic expression of LATS2 increased proliferation and inhibited hepatocyte apoptosis by regulating the Hippo/Yes-associated protein (YAP) signaling pathway. Taken together, our findings indicate that lncRNA NEAT1 might serve as a novel target for FHF therapy due to its regulation of H3K27me3 methylation-dependent promotion of LATS2.

A long noncoding RNA molecule, one that does not encode the synthesis of protein, is implicated in acute liver failure (AHF) and might offer a new target for drugs to treat the condition. AHF can be induced by various factors, including viruses, drugs, alcohol abuse, and inherited traits. Ke Cheng, Yujun Zhao and colleagues at Central South University in Changsha, China investigated the role of this RNA, called NEAT1, in cell and animal models of AHF. They identified increased production of NEAT1, which suppressed liver cell proliferation and promoted liver cell death. They also uncovered molecular details of the mechanisms underlying these effects, in which the RNA altered the production and regulatory modification of certain proteins. Further research should investigate the therapeutic possibilities of interfering with NEAT1 activity.

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.

Phosphorylated Rasal2 facilitates breast cancer progression

BACKGROUND

Rasal2 has diametric effects on progression of oestrogen receptor-positive (ER+) and -negative (ER-) breast cancers. The relevant causes are unknown. It is also unknown whether the effects of Rasal2 are mediated by an exosome-transport process.

METHODS

Exosomes were purified from breast cancer cells and identified by transmission electron microscopy and flow cytometry analysis. In vivo and in vitro experiments were conducted to investigate the role of Rasal2 in exosome-mediated breast cancer progression. Western blot analysis was performed to detect Rasal2 and p-Rasal2 (phosphorylated Rasal2) expression in ER+/ER- breast cancer cells and in exosomes, cancer tissues and blood of patients with ER+ or ER- breast cancer.

FINDINGS

Phosphorylation of Rasal2 at Serine 237 promoted tumour growth in both ER+ and ER- tumour cells and tissues. The functions of both p-Rasal2 and non-p-Rasal2 (non-phosphorylated-Rasal2) in the modulation of breast cancer progression are exosome-mediated. p-Rasal2 expression in ER+ breast cancer cells and exosomes, cancer tissues and blood was significantly lower than in ER- tumour cells and patients.

INTERPRETATION

p-Rasal2 facilitates tumour progression in both ER+ and ER- breast cancers. The ratio of p-Rasal2/non-p-Rasal2 in ER+ and ER- breast cancers is one of the factors deciding the role of Rasal2 (or total Rasal2) as a suppressor in ER+ breast cancers or as a promoter in ER- breast cancers. Targeting the phosphorylation of Rasal2 machinery may therefore be useful as a therapy to restrain breast cancer progression by reducing p-Rasal2/non-p-Rasal2 ratio, especially in ER- breast cancers. FUND: NSFC and Hong Kong Research Grants Council.

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.

Sulforaphane Induces miR135b-5p and Its Target Gene, RASAL2, thereby Inhibiting the Progression of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDA) is one of the most lethal tumors, with poor therapeutic options in the advanced state. The broccoli-derived anti-inflammatory agent sulforaphane was shown to inhibit the progression of pancreatic cancer and other tumor entities. We examined the involvement of pancreatic cancer cell lines were evaluated by microRNA and gene expression arrays, bioinformatics, in silico analysis, qRT-PCR, western blotting, immunohistochemistry, in situ hybridization, self-renewal and differentiation assays, and in vivo xenograft studies. We selected the top nine differentially expressed microRNAs, and miR135b-5p was chosen as the most important candidate for the sulforaphane-induced upregulation of the tumor suppressor gene RASAL2. The expression of miR135b-5p and RASAL2 was almost absent in malignant pancreatic tissues and cell lines, but not in their normal counterparts. Lipofection of miR135b-5p enhanced RASAL2 expression and inhibited ERK1/2 signaling, viability, self-renewal capacity, and tumor growth. These results indicate that miR135b-5p acts as a tumor suppressor via the induction of RASAL2 in PDA.

Mechanotransduction and Cytoskeleton Remodeling Shaping YAP1 in Gastric Tumorigenesis

The essential role of Hippo signaling pathway in cancer development has been elucidated by recent studies. In the gastrointestinal tissues, deregulation of the Hippo pathway is one of the most important driving events for tumorigenesis. It is widely known that Yes-associated protein 1 (YAP1) and WW domain that contain transcription regulator 1 (TAZ), two transcriptional co-activators with a PDZ-binding motif, function as critical effectors negatively regulated by the Hippo pathway. Previous studies indicate the involvement of YAP1/TAZ in mechanotransduction by crosstalking with the extracellular matrix (ECM) and the F-actin cytoskeleton associated signaling network. In gastric cancer (GC), YAP1/TAZ functions as an oncogene and transcriptionally promotes tumor formation by cooperating with TEAD transcription factors. Apart from the classic role of Hippo-YAP1 cascade, in this review, we summarize the current investigations to highlight the prominent role of YAP1/TAZ as a mechanical sensor and responder under mechanical stress and address its potential prognostic and therapeutic value in GC.

A novel protein encoded by a circular RNA circPPP1R12A promotes tumor pathogenesis and metastasis of colon cancer via Hippo-YAP signaling

Background

It has been well established that circular RNAs (circRNAs) play an important regulatory role during tumor progression. Recent studies have indicated that even though circRNAs generally regulate gene expression through miRNA sponges, they may encode small peptides in tumor pathogenesis. However, it remains largely unexplored whether circRNAs are involved in the tumorigenesis of colon cancer (CC).

Methods

The expression profiles of circRNAs in CC tissues were assessed by circRNA microarray. Quantitative real-time PCR, RNase R digestion assay and tissue microarray were used to confirm the existence and expression pattern of circPPP1R12A. The subcellular distribution of circPPP1R12A was analyzed by nuclear mass separation assay and fluorescence in situ hybridization (FISH). SDS-PAGE and LC/MS were employed to evaluate the protein-coding ability of circPPP1R12A. CC cells were stably transfected with lentivirus approach, and cell proliferation, migration and invasion, as well as tumorigenesis and metastasis in nude mice were assessed to clarify the functional roles of circPPP1R12A and its encoded protein circPPP1R12A-73aa. RNA-sequencing and Western blotting analysis were furthered employed to identify the critical signaling pathway regulated by circPPP1R12A-73aa.

Results

We firstly screened the expression profiles of human circRNAs in CC tissues and found that the expression of hsa_circ_0000423 (termed as circPPP1R12A) was significantly increased in CC tissues. We also found that circPPP1R12A was mostly localized in the cytoplasm of CC cells. Kaplan–Meier analysis showed that patients with higher levels of circPPP1R12A had a significantly shorter overall survival. By gain- and loss-of-function approaches, the results suggested that circPPP1R12A played a critical role in proliferation, migration and invasion of CC cells. Furthermore, we showed that circPPP1R12A carried an open reading frame (ORF), which encoded a functional protein (termed as circPPP1R12A-73aa). Next, we found that PPP1R12A-C, not circPPP1R12A, promoted the proliferation, migration and invasion abilities of CC in vitro and in vivo. Finally, we identified that circPPP1R12A-73aa promoted the growth and metastasis of CC via activating Hippo-YAP signaling pathway. In addition, the YAP specific inhibitor Peptide 17 dramatically alleviated the promotive effect of circPPP1R12A-73aa on CC cells.

Conclusions

In the present study, we illustrated the coding-potential of circRNA circPPP1R12A in the progression of CC. Moreover, we identified that circPPP1R12A-73aa promoted the tumor pathogenesis and metastasis of CC via activating Hippo-YAP signaling pathway. Our findings might provide valuable insights into the development of novel potential therapeutic targets for CC.

Electronic supplementary material

The online version of this article (10.1186/s12943-019-1010-6) contains supplementary material, which is available to authorized users.

miR‑3666 suppresses cellular proliferation and invasion in colorectal cancer by targeting SATB2

MicroRNA-3666 (miR-3666) acts as a tumor suppressor in cervical cancer, non-small cell lung cancer and thyroid carcinoma; however, the function of miR-3666 in colorectal cancer (CRC) remains largely unknown. In the present study, was demonstrated that miR-3666 was significantly downregulated in CRC tissues compared with in adjacent normal tissues by reverse transcription-quantitative polymerase chain reaction. Additionally, miR-3666 may serve as a prognostic biomarker for patients with CRC. Via functional experiments, the present study reported that miR-3666 overexpression significantly inhibited the proliferation, migration and invasion of CRC cells as determined by Cell Counting Kit-8 and Transwell assays, and vice versa. In addition, miR-3666 was reported to directly target special AT-rich sequence binding protein 2 (SATB2) in CRC cells; overexpression of miR-3666 significantly suppressed the expression of SATB2 in CRC cells as determined by western blotting. Furthermore, an inverse correlation was observed between the expression levels of miR-3666 and SATB2 in CRC tissues. Restoration of SATB1 expression significantly reversed the effects of miR-3666 mimic on CRC cells. In summary, the results of the present study indicated that miR-3666 may serve as a tumor suppressor in CRC by targeting SATB2.