Downregulation of Notch1 inhibits the invasion and metastasis of human gastric cancer cells SGC7901 and MKN74 in vitro through PTEN activation and dephosphorylation of Akt and FAK

Notch1 signaling pathway promotes growth and metastasis of gastric cancer via modulating CDH5

OBJECTIVE

To explore the underlying molecular mechanism of Notch1/cadherin 5 (CDH5) pathway in modulating in cell malignant behaviors of gastric cancer (GC).

METHODS

We performed bioinformatic analyses to screen the potential target genes of Notch1 from cadherins in GC. Western blot and RT-PCR were conducted to detect CDH5 expression in GC tissues and cells. We utilized chromatin immunoprecipitation (CHIP) assays to assess the interaction of Notch1 with CDH5 gene. The effects of Notch1/CDH5 axis on the proliferation, invasion, migration and vasculogenic mimicry in GC cells were evaluated by EdU, wound healing, transwell, and tubule formation assays.

RESULTS

Significantly increased CDH5 expression was found in GC tissues compared with paracancerous tissues and associated to clinical stage and poor overall survival (OS) in patients with GC. Notch1 positively regulate the expression of CDH5 in GC cells. CHIP assays validated that CDH5 was a direct target of Notch1. In addition, Notch1 upregulation enhanced the proliferation, migration, invasion and vasculogenic mimicry capacity of GC cells, which could be attenuated by CDH5 silencing.

CONCLUSIONS

These results indicated Notch1 upregulation enhanced GC malignant behaviors by triggering CDH5, suggesting that targeting Notch1/CDH5 axis could be a potential therapeutic strategy for GC progression.

FAK family proteins regulate in vivo breast cancer metastasis via distinct mechanisms

Breast cancer is the most commonly diagnosed malignancy and the major leading cause of tumor-related deaths in women. It is estimated that the majority of breast tumor-related deaths are a consequence of metastasis, to which no cure exists at present. The FAK family proteins Proline-rich tyrosine kinase (PYK2) and focal adhesion kinase (FAK) are highly expressed in breast cancer, but the exact cellular and signaling mechanisms by which they regulate in vivo tumor cell invasiveness and consequent metastatic dissemination are mostly unknown. Using a PYK2 and FAK knockdown xenograft model we show here, for the first time, that ablation of either PYK2 or FAK decreases primary tumor size and significantly reduces Tumor MicroEnvironment of Metastasis (TMEM) doorway activation, leading to decreased intravasation and reduced spontaneous lung metastasis. Intravital imaging analysis further demonstrates that PYK2, but not FAK, regulates a motility phenotype switch between focal adhesion-mediated fast motility and invadopodia-dependent, ECM-degradation associated slow motility within the primary tumor. Furthermore, we validate our in vivo and intravital imaging results with integrated transcriptomic and proteomic data analysis from xenograft knockdown tumors and reveal new and distinct pathways by which these two homologous kinases regulate breast tumor cell invasiveness and consequent metastatic dissemination. Our findings identify PYK2 and FAK as novel mediators of mammary tumor progression and metastasis and as candidate therapeutic targets for breast cancer metastasis.

CK2 and the Hallmarks of Cancer

Cancer is a leading cause of death worldwide. Casein kinase 2 (CK2) is commonly dysregulated in cancer, impacting diverse molecular pathways. CK2 is a highly conserved serine/threonine kinase, constitutively active and ubiquitously expressed in eukaryotes. With over 500 known substrates and being estimated to be responsible for up to 10% of the human phosphoproteome, it is of significant importance. A broad spectrum of diverse types of cancer cells has been already shown to rely on disturbed CK2 levels for their survival. The hallmarks of cancer provide a rationale for understanding cancer’s common traits. They constitute the maintenance of proliferative signaling, evasion of growth suppressors, resisting cell death, enabling of replicative immortality, induction of angiogenesis, the activation of invasion and metastasis, as well as avoidance of immune destruction and dysregulation of cellular energetics. In this work, we have compiled evidence from the literature suggesting that CK2 modulates all hallmarks of cancer, thereby promoting oncogenesis and operating as a cancer driver by creating a cellular environment favorable to neoplasia.

Notch1/Hes1‑PTEN/AKT/IL‑17A feedback loop regulates Th17 cell differentiation in mouse psoriasis‑like skin inflammation

IL‑17A, the effector cytokine of T helper (Th) 17 cells, plays a crucial role in the pathogenesis of psoriasis. The Notch1 and PI3K/AKT signaling pathways are implicated in Th17 cell differentiation and IL‑17A production. The present study aimed to evaluate the regulatory effect of the Notch1/hairy and enhancer of split 1 (Hes1)‑PTEN/AKT/IL‑17A feedback loop on Th17 cell differentiation via the PI3K/AKT inhibitor LY294002 in a mouse model of psoriasis. Mice were randomly divided into 3 groups: a control group, a model group [5% imiquimod (IMQ)‑induced group] and an intervention group (5% IMQ‑induced plus LY294002‑treated group). Skin structural characteristics were recorded and evaluated by hematoxylin and eosin staining. The weights of the spleens and inguinal lymph nodes were measured. Th17 cell percentage, as well as the mRNA and protein expression levels of Notch1, Notch1 intracellular domain (NICD1), Hes1, PTEN, AKT, phosphorylated (p)‑AKT, mTOR complex 1 (mTORC1), p‑mTORC1, S6 kinase (S6K)1, S6K2 and IL‑17A were detected in skin samples of the three experimental groups. Additionally, splenic mononuclear cells from model mice were treated by 10 and 50 µM LY294002 to further evaluate its regulatory effect on Notch1/Hes1‑PTEN/AKT/IL‑17A feedback loop. Increased Th17 cell percentage, increased expression of Notch1, NICD1, Hes1, AKT, p‑AKT, mTORC1, p‑mTORC1, S6K1, S6K2 and IL‑17A, and decreased PTEN levels were observed in model mice alongside marked psoriasis‑like skin inflammation, splenomegaly and lymphadenopathy. LY294002 treatment significantly alleviated the severity of psoriasis‑like skin inflammation in the intervention mice, attenuated the degree of epidermal hyperplasia and dermal inflammatory cell infiltration, and mitigated splenomegaly and lymphadenopathy. In addition, LY294002 treatment reversed the increased Th17 cell percentage, as well as the increased expression of Notch1, NICD1, Hes1, AKT, p‑AKT, mTORC1, p‑mTORC1, S6K1, S6K2 and IL‑17A, and the decreased expression of PTEN. In vitro study from 5% IMQ‑induced mouse splenic mononuclear cells presented that high dose of LY294002 exerted more obviously regulatory effect on Notch1/Hes1‑PTEN/AKT/IL‑17A feedback loop. The current findings suggested that the Notch1/Hes1‑PTEN/AKT/IL‑17A feedback loop regulates Th17 cell differentiation within the disease environment of psoriasis. Blocking the Notch1/Hes1‑PTEN/AKT/IL‑17A feedback loop may thus be a potential therapeutic method for management of psoriatic inflammation.

Notch signaling in the pathogenesis, progression and identification of potential targets for cholangiocarcinoma (Review)

Cholangiocarcinoma (CCA) is an aggressive type of bile duct cancer that is characterized by a high mortality rate due to its late diagnosis and ineffective treatment. The aim of the present systematic review was to analyze the association between Notch signaling and CCA in terms of its pathogenesis, progression and potential treatment targets. Relevant information was gathered from the PubMed, ScienceDirect and Scopus databases using the search terms 'cholangiocarcinoma' AND 'Notch signaling'. Of the 90 articles identified, 28 fulfilled the eligibility criteria and were included in the analysis. It was concluded that overexpression/upregulation of Notch ligands, such as Jagged1 and Notch receptors (Notch1, Notch2 and Notch3), as well as upregulation of the upstream Notch signaling pathway, promoted CCA development and progression. In addition, downregulation of Notch1 signaling through several possible interventions appears to be a promising strategy for inhibition of CCA development and progression. Therefore, the Notch signaling pathway may be considered as a potential target for CCA control.

LncRNA ANCR promotes glioma cells invasion, migration, proliferation and inhibits apoptosis via interacting with EZH2 and repressing PTEN expression

Recently, the role of long noncoding RNA (lncRNA) has been identified in human diseases, and we aim to explore the role of lncRNA antidifferentiation noncoding RNA (ANCR) in glioma. Expression of lncRNA ANCR, enhancer of zeste homolog 2 (EZH2), and phosphatase and tensin homolog (PTEN) in glioma tissues and cells was determined by RT-PCR or western blot assay. The correlation between expression of ANCR, EZH2, and PTEN in glioma tissues was analyzed using Pearson test. The apoptosis, transwell invasion, migration, colony formation, and proliferation assays were conducted to evaluate the influences of lncRNA ANCR depletion, EZH2 reduction, or PTEN elevation on the cell biology of glioma cells. The relationships between ANCR and EZH2, and between EZH2 and PTEN were confirmed through RIP, RNA pull-down, and chromatin immunoprecipitation assays. Our results indicated that ANCR and EZH2 were upregulated and PTEN was downregulated in glioma tissues and cell lines. ANCR expression was positively related to EZH2 expression, while PTEN expression was negatively related to ANCR/EZH2 expression. Inhibited ANCR, reduced EZH2, or elevated PTEN could reduce the ability of invasion, migration, and proliferation, and promote apoptosis of glioma cells. PTEN overexpression or EZH2 inhibition reversed the promotive role of ANCR upregulation in glioma cell growth and metastasis. Mechanistically, PTEN was upregulated in ANCR knockdown glioma cells. EZH2 interacted with ANCR in glioma cells. In conclusion, we have found that restrained ANCR could repress invasion, migration, and proliferation, as well as promote apoptosis of glioma cells through interacting with EZH2 and regulating the expression of PTEN, offering an effective therapeutic target for patients with glioma.

The PI3K/Akt/mTOR signaling pathway in gastric cancer; from oncogenic variations to the possibilities for pharmacologic interventions

Genetic and epigenetic alterations have been under concentrated investigations for many years in order to unearth the molecules regulating human cancer pathogenesis. However, the identification of a wide range of dysregulated genes and their protein products has raised a question regarding how the results of this large collection of alterations could converge into a formation of one malignancy. The answer may be found in the signaling cascades that regulate the survival and metabolism of the cells. Aberrancies of each participant molecule of such cascades may well result in augmented viability and unlimited proliferation of cancer cells. Among various signaling pathways, the phosphatidylinositol-3-kinase (PI3K) axis has been shown to be activated in about one-third of human cancers. One of the malignancies that is mostly affected by this axis is gastric cancer (GC), one of the most fatal cancers worldwide. In the present review, we aimed to illustrate the significance of the PI3K/Akt/mTOR axis in the pathogenesis of GC and also provided a wide perspective about the application of the inhibitors of this axis in the therapeutic strategies of this malignancy.

PTEN, a Barrier for Proliferation and Metastasis of Gastric Cancer Cells: From Molecular Pathways to Targeting and Regulation

Cancer is one of the life-threatening disorders that, in spite of excellent advances in medicine and technology, there is no effective cure for. Surgery, chemotherapy, and radiotherapy are extensively applied in cancer therapy, but their efficacy in eradication of cancer cells, suppressing metastasis, and improving overall survival of patients is low. This is due to uncontrolled proliferation of cancer cells and their high migratory ability. Finding molecular pathways involved in malignant behavior of cancer cells can pave the road to effective cancer therapy. In the present review, we focus on phosphatase and tensin homolog (PTEN) signaling as a tumor-suppressor molecular pathway in gastric cancer (GC). PTEN inhibits the PI3K/Akt pathway from interfering with the migration and growth of GC cells. Its activation leads to better survival of patients with GC. Different upstream mediators of PTEN in GC have been identified that can regulate PTEN in suppressing growth and invasion of GC cells, such as microRNAs, long non-coding RNAs, and circular RNAs. It seems that antitumor agents enhance the expression of PTEN in overcoming GC. This review focuses on aforementioned topics to provide a new insight into involvement of PTEN and its downstream and upstream mediators in GC. This will direct further studies for evaluation of novel signaling networks and their targeting for suppressing GC progression.

Origin of Monocytes/Macrophages Contributing to Chronic Inflammation in Chagas Disease: SIRT1 Inhibition of FAK-NFκB-Dependent Proliferation and Proinflammatory Activation of Macrophages

BACKGROUND

Trypanosoma cruzi (Tc) causes Chagas disease (CD) that is the most frequent cause of heart failure in Latin America. TNF-α+ monocytes/macrophages (Mo/Mφ) are associated with inflammatory pathology in chronic CD. In this study, we determined the progenitor lineage of Mo/Mφ contributing to inflammation and examined the regulatory role of SIRT1 in modulating the Mo/Mφ response in Chagas disease.

METHODS AND RESULTS

C57BL/6 mice were infected with Tc, treated with SIRT1 agonist (SRT1720) after control of acute parasitemia, and monitored during chronic phase (150 days post-infection). Flow cytometry studies showed an increase in maturation of bone marrow hematopoietic stem cell (HSC)-derived Mo of proinflammatory and anti-inflammatory phenotype in acutely- and chronically-infected mice; however, these cells were not increased in splenic compartment of infected mice. Instead, yolk-sac-derived CD11b+ F4/80+ Mo/Mφ were increased in sinusoidal compartment of Chagas mice. The splenic CD11b+ F4/80+ Mo/Mφ of Chagas (vs. control) mice exhibited increased mRNA, protein, and surface expression of markers of proinflammatory phenotype (CD80+/CD64+ > CD200+/CD206+) associated with proinflammatory cytokines response (IL-6+TNF-α >> Arg-1+IL-10), and these were also detected in the myocardium of chronically infected mice. Infected mice treated with SRT1720 (vs. infected/untreated) exhibited decreased splenic expansion and myocardial infiltration of proinflammatory Mo/Mφ. SRT1720 did not alter the inherent capability of splenic Mo/Mφ of Chagas mice to respond to pathogen stimulus. Instead, SRT1720 dampened the Tc-induced increase in the expression and/or phosphorylation of focal adhesion kinase (FAK) and downstream transcription factors (Pu.1, c-Myb, and Runx1) involved in Mφ proliferation and migration and Notch1 involved in functional activation. Studies in cultured Mφ confirmed the agonistic effects of SIRT1 in controlling the Tc-induced, FAK-dependent increase in the expression of transcription factors and showed that SIRT1 agonist and FAK inhibitor abrogated the NF-κB transcriptional activity and inflammatory cytokine gene expression in Tc-infected Mφ.

CONCLUSIONS

The proinflammatory Mo/Mφ of yolk sac origin drive the splenic and tissue inflammatory response in chronic CD. SRT1720 reprogrammed the Tc-induced FAK-dependent transcription factors involved in Mφ proliferation and proinflammatory activation in Chagas disease.

Triptonide effectively suppresses gastric tumor growth and metastasis through inhibition of the oncogenic Notch1 and NF-κB signaling pathways

Gastric cancer ranks as the third leading cause of cancer-related death worldwide. The uncontrolled tumor growth and robust metastasis are key factors to cause the cancer patient death. Mechanistically, aberrant activation of Notch and NF-κB signaling pathways plays pivotal roles in the initiation and metastasis of gastric cancer. Despite great efforts have been made in recent decades, the effective drug against the advanced and metastatic gastric cancer is still lacking in the clinical setting. In this study, we found that triptonide, a small molecule (MW358) purified from the traditional Chinese medicinal herb Tripterygium wilfordii Hook F, effectively suppressed tumor growth and metastasis in xenograft mice without obvious toxicity at the doses we tested, resulting in potent anti-gastric cancer effect with low toxicity. Triptonide markedly inhibited human metastatic gastric cancer cell migration, invasion, proliferation, and tumorigenicity. Molecular mechanistic studies revealed that triptonide significantly reduced Notch1 protein levels in metastatic gastric cancer cells through degrading the oncogenic protein Notch1 via the ubiquitin-proteasome pathway. Consequently, the levels of Notch1 downstream proteins RBPJ, IKKα, IKKβ were significantly diminished, and nuclear factor-kappa B (NF-κB) phosphorylation was significantly reduced. Together, triptonide effectively suppresses gastric cancer growth and metastasis via inhibition of the oncogenic Notch1 and NF-κB signaling pathways. Our findings provide a new strategy and drug candidate for treatment of the advanced and metastatic gastric cancer.

Notch1 and PI3K/Akt signaling blockers DAPT and LY294002 coordinately inhibit metastasis of gastric cancer through mutual enhancement

PURPOSE

Blockade of either Notch1 or PI3K/Akt pathway inhibits metastasis of gastric cancer. However, whether blockade of both pathways coordinately exerts such an effect remains unknown. In this study, we aimed to investigate the effects of combined treatment with Notch1 signaling blocker DAPT and PI3K/Akt signal blocker LY294002 on metastasis of gastric cancer.

METHODS

Notch intracellular domain (NICD) and phosphorylated Akt (p-Akt) levels in gastric cancer tissues and their adjacent normal tissue samples and gastric cancer SGC7901 and AGS cells and normal GES-1 cells were determined using immunohistochemistry and Western blotting. The effects of combined DAPT and LY294002 on metastasis of gastric cancer were evaluated by examining migration and invasion potential of SGC7901 cells using wound healing and transwell assays, determining changes in the levels of epithelial-mesenchymal transition biomarkers and MMP-9, Notch1, HES1, and phosphorylation of Akt in gastric cancer SGC7901 cells and/or AGS cells in vitro using Western blotting, and metastasis of gastric cancer to lungs in BALB/c nude mice after treatment.

RESULTS

NICD and p-Akt levels were significantly higher in gastric cancer tissues and SGC7901 and AGS cells than those in the normal control and GES-1 cells. Migration and invasion potential of SGC7901 cells, EMT biomarkers and MMP-9 in SGC7901 cells, and metastasis of gastric cancer to lungs in mice were coordinately inhibited by DAPT and LY294002. In addition, DAPT and LY294002 coordinately inhibited the levels of Notch1, HES1, and p-Akt in gastric cancer cells.

CONCLUSION

DAPT and LY294002 coordinately inhibited metastasis of gastric cancer through mutual enhancement.

The Clinical Implication of PTEN and FAK Expression in Gastric Cancer Patients

Objective:

The tumor suppressor gene phosphatase and tensin homolog (PTEN) was reported to inhibit the growth and invasion of gastric cancer (GC) via the downregulation of focal adhesion kinase (FAK). To date, the clinical implication of PTEN and FAK expression in GC has not been well addressed.

Methods:

A total of 200 GC patients receiving curative surgery were enrolled. The clinicopathologic features according to the expression of PTEN and FAK protein using immunohistochemical staining were compared among patients.

Results:

Patients with high PTEN expression were more likely to have smaller tumor size, more well- and moderately differentiated tumors, a more superficial gross appearance, less scirrhous stromal reactions, more likely to have high FAK expression, and have less advanced pathologic tumor (T) category, node (N) category, and tumor, node, metastasis (TNM) stage and more distant metastases than patients with low PTEN expression. Multivariate analysis showed that PTEN/FAK expression status is an independent prognostic factor affecting overall survival (OS) and disease-free survival (DFS). Patients with PTEN(high)/FAK(low) had better OS and DFS, followed by those with PTEN(high)/FAK(high), those with PTEN(low)/FAK(low), and those with PTEN(low)/FAK(high) (OS: 83.3% versus 58.0% versus 46.2% versus 26.5%, respectively, P < 0.001; DFS: 83.3% versus 55.8% versus 30.8% versus 24.4%, respectively, P < 0.001).

Conclusions:

GC patients with high PTEN expression were more likely to have fewer tumor recurrences and a better prognosis than those with low PTEN expression. PTEN and FAK may have opposing effects on GC patient survival. Our results may have clinical impact on treatment of GC patients.

Effects of the tumor suppressor PTEN on biological behaviors of activated pancreatic stellate cells in pancreatic fibrosis

Pancreatic stellate cells (PSCs), when activated, are characterized by proliferation and collagen synthesis, and contribute to extracellular matrix deposition in pancreatic fibrosis. Concomitantly, fibrosis is linked with the loss of PTEN (phosphatase and tensin homolog) protein in several organs. This study investigated the association between PTEN protein levels and the activated or apoptotic status of PSCs in a rat model of chronic pancreatitis. In addition, the activation status and biological behaviors of culture-activated PSCs were analyzed after lentiviral transfection with wildtype or mutant (G129E) PTEN for upregulation, or PTEN short hairpin RNA for downregulation, of PTEN. In vivo, PTEN levels gradually decreased during pancreatic fibrosis, which positively correlated with apoptosis of activated PSCs, but negatively with PSC activation. In vitro, activated PSCs with wildtype PTEN showed less proliferation, migration, and collagen synthesis compared with control PSCs, and greater numbers were apoptotic; activated PSCs with mutant PTEN showed similar, but weaker, effects. Furthermore, AKT and FAK/ERK signaling was involved in this process. In summary, activated PSCs during pancreatic fibrosis in vivo have lower levels of PTEN. In vitro, PTEN appears to prevent PSCs from further activation and promotes apoptosis through regulation of the AKT and FAK/ERK pathways.

Propranolol inhibits proliferation and invasion of hemangioma-derived endothelial cells by suppressing the DLL4/Notch1/Akt pathway

Infantile hemangioma (IH) is one of the most common benign vascular tumors of infancy. Propranolol has been recently introduced for the treatment of IH. However, the mechanism of protective effect has not been fully understood. In this study, hemangioma-derived endothelial cells (HemECs) were isolated and treated with propranolol. The cell viability was measured by MTT assay, and the cell cycle arrest was detected using flow cytometry. Cell invasion was determined using transwell assay. The expressions of matrix metalloproteinase (MMP)-2, MMP-9, Delta-like 4 (DLL4), Notch1, Akt, p-Akt, and vascular endothelial growth factor (VEGF) were detected using western blot. HemECs were incubated with recombinant human DLL4 (rhDLL4) to investigate the role of DLL4/Notch1 in the effect of propranolol. The results showed that propranolol inhibited cell viability of HemECs in a time-dependent manner. Propranolol suppressed cell proliferation of HemECs by arresting cell progression at G0/G1 phase. Propranolol inhibited the invasion ability of HemECs and reduced the expression levels of MMP-2 and MMP-9 in HemECs. Besides, propranolol treatment blocked the DLL4/Notch1 and Akt signaling and inhibited VEGF expression in HemECs. Treatment with rhDLL4 activated the Akt signaling and attenuated the effect of propranolol on HemECs. Our data indicated that propranolol inhibited the cell proliferation and invasion of HemECs. The effect was possibly involved in the DLL4/Notch1/Akt signaling pathway.

Suppression of Notch1 and AKT mediated epithelial to mesenchymal transition by Verrucarin J in metastatic colon cancer

Epithelial to mesenchymal transition (EMT) in colorectal cancer (CRC) has been attributed to activation of AKT and Notch1 signaling pathways. As EMT corresponds to increased aggressiveness of CRC, approaches that prevent metastasis by targeting AKT/Notch1 pathways are at the forefront of current research paradigms. This study examined the anti-metastatic potential of Verrucarin J (VJ), a small molecule, in CRC cells overexpressing AKT and Notch1. VJ significantly inhibited AKT/HCT 116 cell growth by acting on the AKT/NFκB/Bcl-2 signaling axis and initiated apoptotic signaling as was evident from increased expression of pro-apoptotic markers such as cleaved PARP, cleaved caspase 3, and cleaved caspase 9. Also, VJ inhibited the cell growth in AKT/Notch1-overexpressing CRC cells and abrogated EMT. The down-regulation of AKT and Notch1 signaling was apparent in immunoblot analysis and corresponded with down-regulation of mesenchymal markers including Snail, and β-catenin. Intraperitoneal administration of VJ in control (pCMV/HCT 116) and AKT/HCT 116 mice significantly suppressed AKT-induced tumor growth in a xenograft model. In addition, down-regulation of prosurvival markers as well as AKT and Notch1 was observed in the immunohistochemical analysis of the xenografted tumors. In conclusion, our study substantiates the role of AKT and Notch1 in cell proliferation, angiogenesis, and EMT of CRC cells and demonstrates that VJ may be a viable therapeutic option to counter AKT-induced cell proliferation and tumor outgrowth in CRC.

Suppression of microRNA-495 alleviates high-glucose-induced retinal ganglion cell apoptosis by regulating Notch/PTEN/Akt signaling

High glucose (HG)-induced apoptosis of retinal ganglion cells (RGCs) contributes to the pathogenesis of diabetic retinopathy, which is one of the most common and severe complications of diabetes mellitus. Accumulating evidence has documented that microRNAs (miRNAs) play an important role in the pathogenesis of diabetic retinopathy. However, the role of miRNAs in regulating HG-induced apoptosis of RGCs remains largely unknown. Various studies have suggested that miR-495 is an important regulator of cell apoptosis and survival. In this study, we aimed to investigate whether miR-495 is involved in regulating HG-induced apoptosis of RGCs and reveal its possible relevance in diabetic retinopathy. We found that miR-495 was significantly upregulated in HG-treated RGCs. Downregulation of miR-495 protected RGCs against HG-induced apoptosis, whereas overexpression of miR-495 had the opposite effect. Notably, Notch1 was identified as a target gene of miR-495, as miR-495 negatively regulated Notch1 expression and the Notch signaling pathway. Moreover, downregulation of miR-495 inhibited PTEN expression while promoting Akt activation. However, knockdown of Notch1 significantly abolished the protective effect of miR-495 inhibition against HG-induced apoptosis. Overall, our study suggests that downregulation of miR-495 alleviates HG-induced apoptosis of RGCs by targeting Notch1 to regulate PTEN/Akt signaling, which provides novel insights into understanding the pathogenesis of HG-induced apoptosis of RGCs.

Doxorubicin combined with Notch1-targeting siRNA for the treatment of gastric cancer

Notch1, a transmembrane receptor that has a notable role in gastric cancer (GC) as an oncogene, has been reported to be involved in doxorubicin resistance. Thus, Notch1 is a potential therapeutic target for GC. In the present study, the protein levels of Notch1 intracellular domain (NICD; a marker of Notch1 activation) in human GC cell lines and tumor tissues was measured by western blotting. Next, the effects of Notch1 depletion in SGC7901 cells were evaluated. Finally, the efficacy of Notch1 small interfering RNA (siRNA) combined with doxorubicin therapy for GC was examined in vitro and in vivo. The results revealed that NICD levels were high in GC cells, and that the inhibition of NICD by transfection with Notch1 siRNA induced apoptosis and inhibited proliferation. Ectopic downregulation of Notch1 expression enhanced the sensitivity of GC tumors to doxorubicin, which suppressed the development of GC. These data demonstrated that Notch1 was a significant regulator of cell proliferation and apoptosis in GC. Thus, the combination of doxorubicin with Notch1 siRNA is a potential strategy for the treatment of GC.

Tumor-Suppressive MicroRNA-708 Targets Notch1 to Suppress Cell Proliferation and Invasion in Gastric Cancer

Growing evidence has demonstrated that numerous microRNAs (miRNAs) may participate in the regulation of gastric carcinogenesis and progression. This phenomenon suggests that gastric cancer-related miRNAs can be identified as effective therapeutic targets for this disease. miRNA-708 (miR-708) has recently been reported to be aberrantly expressed in several types of cancer and contribute to carcinogenesis and progression. However, the expression level, biological roles, and underlying mechanisms of miR-708 in gastric cancer are poorly understood. Here we found that miR-708 was downregulated in gastric cancer tissues and cell lines. Downregulated miR-708 expression was significantly associated with lymphatic metastasis, invasive depth, and TNM stage. Further investigation indicated that ectopic expression of miR-708 prohibited cell proliferation and invasion in gastric cancer. Bioinformatics analysis showed that Notch1 was a potential target of miR-708. Notch1 was further confirmed as a direct target gene of miR-708 in gastric cancer by dual-luciferase reporter assay, reverse transcription quantitative polymerase chain reaction, and Western blot analysis. Furthermore, an inverse association was found between miR-708 and Notch1 mRNA levels in gastric cancer tissues. In addition, restored Notch1 expression rescued the inhibitory effects on gastric cancer cell proliferation and invasion induced by miR-708 overexpression. Our findings highlight the tumor-suppressive roles of miR-708 in gastric cancer and suggest that miR-708 may be investigated as a novel target for gastric cancer treatment.

Bioinformatics prediction of miR-30a targets and its inhibition of cell proliferation of osteosarcoma by up-regulating the expression of PTEN

BACKGROUND

MiRNAs are frequently abnormally expressed in the progression of human osteosarcoma. Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is one of the tumor suppressors in various types of human cancer. In the present study, we detected how hsa-miR-30a-3p regulated PTEN and further tested the role of hsa-miR-30a-3p in the cell proliferation of osteosarcoma cells.

METHODS

The levels of miR-30a were determined by real time PCR. The expression of PTEN was tested by western blotting analysis. Cell distribution of PTEN was observed with confocal laser scanning microscope. Cell viability was determined by MTT assay.

RESULTS

The expression of miR-30a and PTEN was obviously decreased in MG-63, 143B and Saos-2 cells compared with primary osteoblasts. TargetScan analysis data showed miR-30a might bind with position 30-57 of 3'UTR of PTEN. Transfection with miR-30a-3p increased the level of PTEN in MG-63 cells, while transfection with miR-30a-3p inhibitor significantly decreased the expression of PTEN in osteosarcoma cells. Transfection with miR-30a-3p significantly inhibited cell proliferation of osteosarcoma cells, while miR-30a inhibitor obviously promoted cell viability of MG63 cells and Saos-2 cells. Inhibition of PTEN eliminated the proliferation inhibitory effect of miR-30a-3p.

CONCLUSION

Thus, all these findings revealed the anti-tumor effects of miR-30a in human osteosarcoma cells, which could be mediated by regulating the level of PTEN.