Inhibition of FoxO1 nuclear exclusion prevents metastasis of glioblastoma

Long noncoding RNA matrilineal expression gene 3 inhibits hepatocellular carcinoma progression by targeting microRNA-5195-3p and regulating the expression of forkhead box O1

We investigated the effect of the long noncoding RNA (lncRNA) maternally expressed gene 3 (MEG3) on hepatocellular carcinoma (HCC) tumorigenesis and progression by targeting miR-5195-3p and transcription factor forkhead box O1 (FOXO1) to identify a novel target for HCC treatment. HCC clinical samples were collected, and cell counting kit-8 (CCK-8), and transwell migration and invasion assays were performed. Furthermore, interaction was detected via double luciferase reporter and RNA pull-down assays. MEG3, miR-5195-3p, and FOXO1 expression was determined by quantitative real-time polymerase chain reaction (RT-qPCR) and Western blotting. Xenograft tumor models were established to investigate the effect of MEG3 in vivo. Compared with normal tissues, MEG3 expression was significantly downregulated in HCC tissues. MEG3 overexpression inhibited the viability and migration of HCC cells. Double luciferase reporter and RNA pull-down assays confirmed the binding between MEG3 and miR-5195-3p as well as between miR-5195-3p and FOXO1. RT-qPCR and Western blotting results showed that MEG3 inhibited the expression of miR-5195-3p and promoted that of FOXO1. Additionally, MEG3 overexpression inhibited HCC tumorigenesis and progression in xenograft tumor models while depletion of MEG3 exerted the opposite way. Therefore, the lncRNA MEG3 inhibits HCC tumorigenesis and progression through the miR-5195-3p/FOXO1 signaling axis.

The essential role of long non-coding RNA GAS5 in glioma: interaction with microRNAs, chemosensitivity and potential as a biomarker

Glioma is a malignant brain tumor with a generally poor prognosis. Dysregulation of a long non-coding RNA, GAS5, has been detected in numerous cancers, including glioma. Previous studies have suggested that GAS5 plays a significant functional role in glioma, affecting proliferation, metastasis, invasion, and apoptosis. In this review, we describe the roles and mechanisms of GAS5 in glioma. GAS5 may be a biomarker for diagnosis and prognosis, and even a potential target for glioma treatment, and therefore warrants further investigation.

Multi-omics analysis identifies FoxO1 as a regulator of macrophage function through metabolic reprogramming

Macrophages are plastic cells that can switch among different states according to bioenergetic or biosynthetic requirements. Our previous work demonstrated that the transcription factor Forkhead Box Protein 1 (FoxO1) plays a pivotal role in regulating the function of macrophages, but the underlying mechanisms are still unclear. Here we identify FoxO1 as a regulator of macrophage function through metabolic reprogramming. Transcriptomic and proteomic analyses showed that the deficiency of FoxO1 results in an alternatively activated (M2) phenotype of macrophages, with lower expression of inflammatory response- and migration-associated genes. Using the high content screening and analysis technology, we found that deletion of FoxO1 in macrophages slows their migration rate and impairs their function to limit tumor cell growth in vitro. Next, we demonstrated that glycolysis is inhibited in FoxO1-deficient macrophages, which leads to the observed functional changes and the reduced tumor suppression capability. This prospective study shows that FoxO1 serves as a bridge between metabolism and macrophage function.

STAT3 Promotes Invasion and Aerobic Glycolysis of Human Oral Squamous Cell Carcinoma via Inhibiting FoxO1

Signal transducer and activator of transcription 3 (STAT3), a previously accepted tumor-promoting protein in various malignancies, plays a key role in the process of cancer glycolysis. However, the role and potential mechanism of STAT3 in aerobic glycolysis and progression of oral squamous cell carcinoma (OSCC) has not been explored. In the present study, we demonstrated that STAT3 knockdown remarkably inhibited migration, invasion, expressions of epithelial-mesenchymal transition (EMT) markers, and aerobic glycolysis of OSCC cells by up-regulation of FoxO1. Consistently, the expression of nuclear Tyr705-phosphorylated STAT3, an active form of STAT3, was significantly elevated in OSCC tissues compared with adjacent normal tissues, and increased nuclear staining of Tyr705-phosphorylated STAT3 was associated with metastasis and shorter overall survival. Moreover, FoxO1, which was also mainly expressed in OSCC specimens, decreased in poorly-differentiated tissues compared with the relatively well-differentiated ones, and inversely correlated with the expression of nuclear Tyr705-phosphorylated STAT3 from patients with OSCC. Hence, our findings collectively characterized the contributing role of STAT3/FoxO1 in invasion and aerobic glycolysis of OSCC cells, which may lead to the worse clinical outcome.

The Application of FOXO1A Expression Predicts Aggressive Behavior and Poor Prognosis in Gliomas

Forkhead box, class O, 1A (FOXO1A) is an important factor related to some human malignancies. We tested the association between FOXO1A cytoplasmic expression and World Health Organization grading system in primary brain tumors (PBTs). First of all, Western blot analysis was also performed in normal brain tissue and U87MG, LN229, GBM8401, and U118MG glioma cell lines protein lysates. Then, in order to realize FOXO1A gene expression in gliomas, U87MG, LN229, GBM8401 mRNA were applied to performed quantitative reverse transcription polymerase chain reaction (RT-PCR). At last, the immunohistochemical (IHC) analysis of FOXO1A was performed in 8 non-neoplastic brain tissues and 126 PBTs. The immunostain scores were obtained as the degree of cytoplasmic FOXO1A intensity multiplied by the percentage of positively stained tumor area. On the basis of the results of these in vitro studies, marked increase FOXO1A protein and mRNA expressions in glioma cell lines than in normal human tissue. On the view point of IHC stains, the average immunostain score of FOXO1A in all PBTs was significantly higher than non-neoplastic brain tissues. In addition, the immunostain scores of FOXO1A in high grade were higher than low-grade gliomas. Furthermore, higher cytoplasmic expression of FOXO1A might indicate the shorter overall survival rate in gliomas. Furthermore, FOXO1A expression was associated with isocitrate dehydrogenase I /2, ATRX, and p53 mutation by IHC staining. Therefore, the application of FOXO1A IHC stain might have some benefits to improve diagnostic accuracy, predict tumor progression, and evaluate survival time in glioma patients.

miR-182 and miR-183 Promote Cell Proliferation and Invasion by Targeting FOXO1 in Mesothelioma

Dysregulation of miR-182 and miR-183 has been implicated in the progression of several human cancers. Our previous study showed that miR-182 and miR-183 are upregulated in malignant mesothelioma. However, their biological functions remain unclear. We performed in-situ hybridization to analyze the expression of miR-182 and miR-183 in human tissues. Functional analysis was performed by treatment of two mesothelioma cell lines (ACC-MESO1 and CRL-5915) with miR-182 and miR-183 inhibitors. RT-PCR and western blot analysis were conducted to analyze the expression of FOXO1, a known target of both miR-182 and miR-183. Mesothelioma cells treated with FOXO1 siRNA and miR-182/183 inhibitors were also analyzed by evaluating cell proliferation and invasion, as well as expression of FOXO1 and its downstream targets. We confirmed miR-182 expression in 25/29 cases and miR-183 expression in 29/29 cases of human mesothelioma tissue by in-situ hybridization. Notably, inhibition of miR-182 or miR-183 reduced cell proliferation, invasion, migration, and adhesion abilities of mesothelioma cells. Surprisingly, transfection with both miR-182 and miR-183 inhibitors showed even more effects on cell progression. Furthermore, FOXO1 was identified as a target of miR-182 and miR-183 in mesothelioma cells. Inhibition of miR-182 and miR-183 reduced cell proliferation ability via upregulation of FOXO1 and its downstream targets, namely, p27. Moreover, inhibition of miR-182 and miR-183 reduced the cell invasion properties of mesothelioma cells. Our findings indicated that miR-182 and miR-183 promote mesothelioma cell progression via downregulation of FOXO1 and p27. Targeting the miR-182/183—FOXO1 axis could serve as a novel treatment against malignant mesothelioma.

Chemo-resistance of A172 glioblastoma cells is controlled by miR-1271-regulated Bcl-2

MicroRNAs (miRNAs) have been reported to exert important effects on the initiation, progression and metastasis of glioblastoma multiforme (GBM). In this study, we aimed to explore the regulation role of miR-1271 on the development of GBM. We found that miR-1271 was a Bcl-2-targeting miRNA, and the levels of miR-1271was decreased in samples from patients with GBM, compared with those from corresponding normal tissue samples. On the other hand, the levels of miR-1271 were inversely related to the levels of Bcl-2, which have been significantly increased in GBM samples. The overall survival was poorer in patients with low levels of miR-1271, compared to those with high levels of miR-1271. In vitro, the chemo-resistant cell survival mediated with Bcl-2 was inhibited by overexpression of miR-1271 and was enhanced by depletion of miR-1271. Thus, the chemo-resistance of GBM cells may be promoted after suppressing miR-1271 through cell survival mediated with Bcl-2. The prognosis of patients with GBM receiving chemotherapy may be improved by overexpressing miR-1271 in cancerous cells.

Role of Forkhead Box Class O proteins in cancer progression and metastasis

It is now widely accepted that several gene alterations including transcription factors are critically involved in cancer progression and metastasis. Forkhead Box Class O proteins (FoxOs) including FoxO1/FKHR, FoxO3/FKHRL1, FoxO4/AFX and FoxO6 transcription factors are known to play key roles in proliferation, apoptosis, metastasis, cell metabolism, aging and cancer biology through their phosphorylation, ubiquitination, acetylation and methylation. Though FoxOs are proved to be mainly regulated by upstream phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3 K)/Akt signaling pathway, the role of FoxOs in cancer progression and metastasis still remains unclear so far. Thus, with previous experimental evidences, the present review discussed the role of FoxOs in association with metastasis related molecules including cannabinoid receptor 1 (CNR1), Cdc25A/Cdk2, Src, serum and glucocorticoid inducible kinases (SGKs), CXCR4, E-cadherin, annexin A8 (ANXA8), Zinc finger E-box-binding homeobox 2 (ZEB2), human epidermal growth factor receptor 2 (HER2) and mRNAs such as miR-182, miR-135b, miR-499-5p, miR-1274a, miR-150, miR-34b/c and miR-622, subsequently analyzed the molecular mechanism of some natural compounds targeting FoxOs and finally suggested future research directions in cancer progression and metastasis.

LAMB3 mediates metastatic tumor behavior in papillary thyroid cancer by regulating c-MET/Akt signals

Laminin subunit beta-3 (LAMB3) encodes one of the three subunits of LM-332, a protein of the extracellular matrix secreted by cultured human keratinocytes. While LAMB3 is involved in the invasive and metastatic abilities of several tumor types, including those found in the colon, pancreas, lung, cervix, stomach, and prostate, its mechanism of action in thyroid cancer has not been investigated previously. Our results show that LAMB3 is up-regulated in papillary thyroid cancer, and that its suppression reduces cell migration/invasion via down-regulation of epithelial‒mesenchymal transition-associated proteins (N-cadherin, vimentin, slug) and inhibition of matrix metalloproteinase 9. LAMB3 suppression also significantly decreases Akt phosphorylation and inhibits the transcription of c-MET, reducing its activation. These results suggest that LAMB3 leads to tumor invasion via Akt activation induced by the HGF/c-MET axis in papillary thyroid cancer cells. Our findings reveal a novel mechanism of action for LAMB3 in papillary thyroid cancer cells.

Forkhead box O proteins: Crucial regulators of cancer EMT

The epithelial-mesenchymal transition (EMT) is an acknowledged cellular transition process in which epithelial cells acquire mesenchymal-like properties that endow cancer cells with increased migratory and invasive behavior. Forkhead box O (FOXO) proteins have been shown to orchestrate multiple EMT-associated pathways and EMT-related transcription factors (EMT-TFs), thereby modulating the EMT process. The focus of the current review is to evaluate the latest research progress regarding the roles of FOXO proteins in cancer EMT. First, a brief overview of the EMT process in cancer and a general background on the FOXO family are provided. Next, we present the interactions between FOXO proteins and multiple EMT-associated pathways during malignancy development. Finally, we propose several novel potential directions for future research. Collectively, the information compiled herein should serve as a comprehensive repository of information on this topic and should aid in the design of additional studies and the future development of FOXO proteins as therapeutic targets.

FoxO1 is a regulator of MHC-II expression and anti-tumor effect of tumor-associated macrophages

Macrophages are a critical component in host immune responses against tumor. In this work we investigated the role of forkhead box O1 (FoxO1) in the transcriptional regulation in macrophages, which affects the anti-tumor functions of tumor-associated macrophages (TAMs). First, we showed that TAMs expressed reduced levels of FoxO1, which was associated with their protumoral M2 polarization state. The suppression of FoxO1 expression in TAM was induced by the hypoxic condition in the tumor microenviroment. Next, we confirmed that FoxO1 positively regulates MHC-II genes by binding to the promoter region of Ciita gene, the master activator of multiple MHC-II genes. Loss of FoxO1 in TAMs resulted in reduced MHC-II expression. Furthermore, we used FoxO1 conditional knockout mice to show that FoxO1 deficiency in myeloid cells exacerbates tumor growth. These results demonstrate that the protumoral property of TAMs is induced by the hypoxia-triggered FoxO1 deficiency, which could be a potential target of novel anti-tumor therapies.

GAS5 suppresses malignancy of human glioma stem cells via a miR-196a-5p/FOXO1 feedback loop

Glioma stem cells (GSCs) make up highly tumorigenic subpopulations within gliomas, and aberrant expression of GSC genes is a major underlying cause of glioma pathogenesis and treatment failure. The present study characterized the expression and function of long non-coding RNA growth arrest specific 5 (GAS5) in GSCs in order to elucidate the molecular mechanisms by which GAS5 contributes to glioma pathogenesis. We demonstrate that GAS5 suppresses GSC malignancy by binding to miR-196a-5p. miR-196a-5p, an onco-miRNA, stimulates GSC proliferation, migration, and invasion, in addition to reducing levels of apoptosis. miR-196a-5p specifically downregulates the expression of forkhead box protein O1 (FOXO1) by targeting its 3' untranslated region (3'-UTR). FOXO1 upregulates expression of phosphotyrosine interaction domain containing 1 (PID1), thereby inhibiting GSC tumorigenicity and growth. FOXO1 also upregulates migration and invasion inhibitory protein (MIIP), resulting in attenuation of migration and invasion activities. Interestingly, we also show that FOXO1 promotes GAS5 transcription, thus forminga positive feedback loop. These data provide insights into potential new pathways for GSC molecular therapy and suggest that GAS5 may be an efficacious target for glioma treatments.

Norcantharidin modulates miR-655-regulated SENP6 protein translation to suppresses invasion of glioblastoma cells

Norcantharidin (NCTD) is currently used as an anticancer drug for the treatment of some malignant cancers. However, whether it may have therapeutic effects on glioblastoma multiforme (GBM) remains unknown. Moreover, the underlying mechanisms have not been completely elucidated. Recently, SUMO-specific protease 6 (SENP6) has been shown as a tumor suppressor in some cancers. Nevertheless, whether it is involved in the pathogenesis of GBM has not been examined. Here, we studied the effects of NCTD on GBM cells. We found that NCTD dose-dependently increased SENP6 protein, but not messenger RNA (mRNA), in GBM cells, resulting in the suppression of cell invasion. Depletion of SENP6 in GBM cells significantly attenuated the NCTD-induced suppression of GBM cell invasion, while overexpression of SENP6 in GBM cells mimicked the effects of NCTD on cell invasion. Moreover, NCTD dose-dependently decreased the levels of microRNA-655 (miR-655), which bound to 3'-UTR of SENP6 mRNA to inhibit its translation. Overexpression of miR-655 decreased SENP6 in GBM cells, while depletion of miR-655 increased SENP6 protein in GBM cells. Taken together, our data demonstrates a previously unappreciated control of NCTD to suppress GBM cell invasion through modulation of miR-655-regulated SENP6 protein translation.

MiR-429 induces apoptosis of glioblastoma cell through Bcl-2

An essential role of microRNAs (miRNAs) has been acknowledged in the tumorigenesis of glioblastoma multiforme (GBM). Very recently, miR-429 was reported to have a potential of suppressing cancer growth. However, whether miR-429 may similarly regulate growth of GBM remains unknown. Here, we analyzed the levels of miR-429 and anti-apoptotic protein Bcl-2 in GBM specimens. We combined bioinformatics analyses and luciferase reporter assay to determine the relationship between miR-429 and Bcl-2 in GBM cells. Cell survival upon temozolomide treatment was analyzed in a CCK assay. Cell apoptosis was measured by fluorescein isothiocyanate (FITC) Annexin V apoptosis detection assay. We found that miR-429 levels were significantly decreased and Bcl-2 levels were significantly increased in GBM specimens, compared to the paired adjacent non-tumor brain tissue. Moreover, the levels of miR-429 and Bcl-2 inversely correlated. Low-miR-429 subjects had an overall inferior survival, compared to high-miR-429 subjects. MiR-429 targeted the 3'-UTR of Bcl-2 mRNA to inhibit its translation. Overexpression of miR-429 inhibited Bcl-2-mediated cell survival against temozolomide-induced apoptosis, while depletion of miR-429 augmented it. Together, our data suggest that miR-429 suppression in GBM promotes Bcl-2-mediated cancer cell survival against chemotherapy-induced cell death. Re-expression of miR-429 levels in GBM cells may improve the outcome of chemotherapy.

Ginsenoside Rh2 inhibits invasiveness of glioblastoma through modulation of VEGF-A

The malignancy of glioblastoma multiforme (GBM) is largely due to its local invasion and the presence of the tumor in the relatively restrained region in the brain. Hence, effective prevention of the cancer cell invasion is substantially critical for controlling the growth and deterioration of GBM. We have recently reported the role of ginsenoside Rh2 (GRh2) in suppressing the growth of GBM through EGFR/PI3k/Akt/mTor signaling pathways. Here, we further showed that GRh2 efficiently inhibited the cancer vascularization in vivo. In vitro, GRh2 dose-dependently inhibited the protein, but not messenger RNA (mRNA) of vascular endothelial growth factor A (VEGF-A) in GBM cells. We then examined the underlying mechanisms and found that GRh2 increased the levels of miR-497, which bound to 3'UTR of VEGF-A mRNA to inhibit its translation. Together, our data demonstrate a previously unappreciated role for GRh2 in inhibition of GBM-associated cancer vascularization, which may contribute to the effects of GRh2 on suppression of GBM cancer growth and invasion.

Isorhapontigenin (ISO) Inhibits Invasive Bladder Cancer Formation In Vivo and Human Bladder Cancer Invasion In Vitro by Targeting STAT1/FOXO1 Axis

Although our most recent studies have identified Isorhapontigenin (ISO), a novel derivative of stilbene that isolated from a Chinese herb Gnetum cleistostachyum, for its inhibition of human bladder cancer growth, nothing is known whether ISO possesses an inhibitory effect on bladder cancer invasion. Thus, we addressed this important question in current study and discovered that ISO treatment could inhibit mouse-invasive bladder cancer development following bladder carcinogen N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) exposure in vivo We also found that ISO suppressed human bladder cancer cell invasion accompanied by upregulation of the forkhead box class O 1 (FOXO1) mRNA transcription in vitro Accordingly, FOXO1 was profoundly downregulated in human bladder cancer tissues and was negatively correlated with bladder cancer invasion. Forced expression of FOXO1 specifically suppressed high-grade human bladder cancer cell invasion, whereas knockdown of FOXO1 promoted noninvasive bladder cancer cells becoming invasive bladder cancer cells. Moreover, knockout of FOXO1 significantly increased bladder cancer cell invasion and abolished the ISO inhibition of invasion in human bladder cancer cells. Further studies showed that the inhibition of Signal transducer and activator of transcription 1 (STAT1) phosphorylation at Tyr701 was crucial for ISO upregulation of FOXO1 transcription. Furthermore, this study revealed that metalloproteinase-2 (MMP-2) was a FOXO1 downstream effector, which was also supported by data obtained from mouse model of ISO inhibition BBN-induced mouse-invasive bladder cancer formation. These findings not only provide a novel insight into the understanding of mechanism of bladder cancer's propensity to invasion, but also identify a new role and mechanisms underlying the natural compound ISO that specifically suppresses such bladder cancer invasion through targeting the STAT1-FOXO1-MMP-2 axis. Cancer Prev Res; 9(7); 567-80. ©2016 AACR.

Loss of FOXO1 promotes gastric tumour growth and metastasis through upregulation of human epidermal growth factor receptor 2/neu expression

BACKGROUND

The biological significance of FOXO1, a member of the forkhead box O transcription factor family, in gastric cancer (GC) remains unclear. The present study provides direct evidence of the role of FOXO1 in tumour growth and metastasis of GC in relation to human epidermal growth factor receptor 2 (HER2).

METHODS

The expressions of FOXO1 and HER2 were modulated in GC cell lines (SNU-638, MKN45, SNU-216 and NCI-N87) by stable transfections. The effects of transfection on GC phenotypes were evaluated in vitro and in animal models. In addition, the relationship between FOXO1 and HER2 was analysed using GC clinical specimens, cell lines and xenografts.

RESULTS

FOXO1 silencing in GC cells increased colony formation and mesenchymal transition in vitro, as well as tumour growth and metastasis in nude mice, whereas HER2 silencing induced the opposite results.. Furthermore, an inverse relationship between FOXO1 and HER2 was found in clinical specimens of GC, GC cells and GC xenograft tumours. Although a negative crosstalk between these two molecules was shown, double knockdown of both FOXO1 and HER2 in GC cells revealed that HER2 silencing reversed the FOXO1 shRNA-induced migration and invasion even without the FOXO1 restoration.

CONCLUSIONS

Our results indicate that loss of FOXO1 promotes GC growth and metastasis by upregulating HER2 expression and that the HER2 expression is more critical to the induction of GC cell metastasis. The present study provides evidence that the FOXO1/HER2 pathway may regulate GC progression in a subgroup of GC patients.

Larynx carcinoma regulates tumor-associated macrophages through PLGF signaling

Cancer neovascularization plays an essential role in the metastasis of larynx carcinoma (LC). However, the underlying molecular mechanisms are not completely understood. Recently, we reported that placental growth factor (PLGF) regulates expression of matrix metalloproteinase 3 (MMP3) through ERK/MAPK signaling pathway in LC. Here, we show that MMP9 upregulated in LC, and appeared to be mainly produced by M2 macrophages (tumor-associated macrophages (TAM)). In a transwell co-culture system, PLGF secreted by LC cells triggered macrophage polarization to a TAM subtype that releases MMP9. Moreover, MMP9 was found to be activated in the PLGF-polarized TAM via transforming growth factor β (TGFβ) receptor signaling activation. Furthermore, PLGF in LC cells induced macrophage polarization in vivo, and significantly promoted the growth of LC. Thus, together with our previous work, our study highlights a pivotal role of cross-talk between TAM and LC in regulating the metastasis of LC.

Ginsenoside Rh2 inhibits metastasis of glioblastoma multiforme through Akt-regulated MMP13

Glioblastoma multiforme (GBM) is the most malignant type of primary brain tumor. Although the growth of the tumor cells in a relatively closed space may partially account for its malignancy, highly invasive nature of glioblastoma cells has been suggested to be the main reason for the failure of current therapeutic approaches. Ginsenoside Rh2 (GRh2) has recently been shown to significantly suppress the growth and survival of GBM through inhibiting epidermal growth factor receptor signaling, whereas its effects on the invasion and metastasis have not been examined. Here, we showed that GRh2 dose-dependently decreased GBM cell invasiveness in both scratch wound healing assay and Transwell cell migration assay. Moreover, the inhibitory effects of GRh2 on cell migration seemed to be conducted through decreased expression of matrix metalloproteinase (MMP)-13. Furthermore, using specific inhibitors, we found that GRh2 inhibited MMP13 through PI3k/Akt signaling pathway. Finally, high MMP13 levels were detected in GBM specimen from the patients. Together, these data suggest that GRh2 may suppress GBM migration through inhibiting Akt-mediated MMP13 activation. Thus, our data highlight a previous unappreciated role for GRh2 in suppressing GBM cell metastasis.

SEMA4B inhibits growth of non-small cell lung cancer in vitro and in vivo

We have recently shown that Semaphorin 4B (SEMA4B) inhibits the invasion of non-small cell lung cancer (NSCLC) through PI3K-dependent suppression of MMP9 activation. In the current study, we evaluated whether SEMA4B may also affect the growth of NSCLC. We thus used two human NSCLC lines, A549 and Calu-3, to examine our hypothesis. We found that overexpression of SEMA4B significantly decreased NSCLC cell growth, while SEMA4B inhibition significantly increased NSCLC cell growth, both in vitro and in vivo in an implanted NSCLC model. Adaptation of SEMA4B in NSCLC cells did not alter cell apoptosis, but changed the cell proliferation. Further analyses show that SEMA4B may induce FoxO1 nuclear retention through suppressing PI3K/Akt signaling pathway, which subsequently inhibited cell growth through the direct nuclear target of FoxO1, p21. Our study thus demonstrate a role of SEMA4B in suppressing NSCLC growth, besides its role in inhibiting cell metastasis, and highlights SEMA4B as a promising therapeutic target for NSCLC.

Interplay of miR-21 and FoxO1 modulates growth of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant primary tumors in humans, with extremely high lethality. Although great efforts have been made to understand the molecular regulation of the tumorigenesis of PDAC, our current knowledge remains very limited. Previous work has shown a possible involvement of miR-21 in the growth of PDAC, whereas the underlying mechanism has not been clarified. Here, we show significant higher levels of miR-21 in PDAC, compared to the adjacent normal pancreatic tissue. Moreover, overexpression of miR-21 in PDAC cells increased cell growth, whereas inhibition of miR-21 decreased cell growth. Furthermore, miR-21 was found to inhibit nuclear retention of FoxO1 to augment the growth of PDAC cells. Thus, miR-21/FoxO1 axis appears to be a novel therapeutic target for inhibiting the growth of PDAC.

Insulin-like growth factor 1 promotes growth of gastric cancer by inhibiting foxo1 nuclear retention

Gastric cancer (GC) is the fourth most common malignant human cancer. So far, the molecular mechanisms underlying the tumorigenesis of GC are not completely understood. Here, we reported significantly higher levels of serum insulin-like growth factor (IGF)-1 in GC patients and significantly higher levels of phosphorylated IGF-1 receptor (IGF-1R) in the GC specimen. Moreover, IGF-1 induced phosphorylation of IGF-1R and then phosphorylation of its downstream factor Akt in the GC cells. Further, IGF-1/Akt-induced forkhead box protein O1 (FoxO1) nuclear exclusion, but not IGF-1/Akt-induced mTOR phosphorylation, was essential for the augment in GC cell growth. Together, IGF-1/Akt/FoxO1 regulatory machinery appears to be a previously unappreciated signaling axis involved in the carcinogenesis of GC.

Ginsenoside Rh2 inhibits growth of glioblastoma multiforme through mTor

Being the most malignant primary brain tumor in humans, glioblastoma multiforme (GBM) has a fairly poor patient survival after current combined treatment with chemotherapy, radiation, and surgery. Ginsenoside Rh2 (GRh2) has been reported to have a therapeutic effect on some tumors, and we recently reported its inhibitory effect on GBM growth in vitro and in vivo, possibly through an epidermal growth factor receptor (EGFR) signaling pathway. Here, using specific inhibitors, we found that the activation of EGFR signaling promoted GBM growth through PI3k/Akt/mTor signaling pathways. Moreover, GRh2 efficiently inhibited activation of this pathway at the receptor level. Together with our previous findings, these data suggest that GRh2 may suppress GBM growth through its competition with EGFR ligands for binding to the EGFR, and binding to EGFR by GRh2 does not lead to receptor phosphorylation. Thus, our data highlight a previous unappreciated role for GRh2 to inhibit EGFR signaling. GRh2 thus appears to be a promising therapy for cancers that require EGFR signaling to growth.

PDGF receptor alpha inhibition induces apoptosis in glioblastoma cancer stem cells refractory to anti-Notch and anti-EGFR treatment

BACKGROUND

Cancer stem cells (CSC) represent a rare fraction of cancer cells characterized by resistance to chemotherapy and radiation, therefore nowadays there is great need to develop new targeted therapies for brain tumors and our study aim to target pivotal transmembrane receptors such as Notch, EGFR and PDGFR, which are already under investigation in clinical trials setting for the treatment of Glioblastoma Multiforme (GBM).

METHODS

MTS assay was performed to evaluate cells response to pharmacological treatments. Quantitative RT-PCR and Western blots were performed to state the expression of Notch1, EGFR and PDGFRα/β and the biological effects exerted by either single or combined targeted therapy in GBM CSC. GBM CSC invasive ability was tested in vitro in absence or presence of Notch and/or EGFR signaling inhibitors.

RESULTS

In this study, we investigated gene expression and function of Notch1, EGFR and PDGFR to determine their role among GBM tumor core- (c-CSC) vs. peritumor tissue-derived cancer stem cells (p-CSC) of six cases of GBM. Notch inhibition significantly impaired cell growth of c-CSC compared to p-CSC pools, with no effects observed in cell cycle distribution, apoptosis and cell invasion assays. Instead, anti-EGFR therapy induced cell cycle arrest, sometimes associated with apoptosis and reduction of cell invasiveness in GBM CSC. In two cases, c-CSC pools were more sensitive to simultaneous anti-Notch and anti-EGFR treatment than either therapy alone compared to p-CSC, which were mostly resistant to treatment. We reported the overexpression of PDGFRα and its up-regulation following anti-EGFR therapy in GBM p-CSC compared to c-CSC. RNA interference of PDGFRα significantly reduced cell proliferation rate of p-CSC, while its pharmacological inhibition with Crenolanib impaired survival of both CSC pools, whose effects in combination with EGFR inhibition were maximized.

CONCLUSIONS

We have used different drugs combination to identify the more effective therapeutic targets for GBM CSC, particularly against GBM peritumor tissue-derived CSC, which are mostly resistant to treatments. Overall, our results provide the rationale for simultaneous targeting of EGFR and PDGFR, which would be beneficial in the treatment of GBM.

Androgen receptor signaling regulates growth of glioblastoma multiforme in men

Although glioblastoma multiforme (GBM) is the most malignant primary human brain cancer with surprisingly high incidence rate in adult men than in women, the exact mechanism underlying this pronounced epidemiology is unclear. Here, we showed significant upregulated androgen receptor (AR) expression in the GBM tissue compared to the periphery normal brain tissue in patients. An expression of AR was further detected in all eight examined human GBM cell lines. To figure out whether AR signaling may play a role in GBM, we used high AR-expressing U87-MG GBM line for further study. We found that activation of transforming growth factor β (TGFβ) receptor signaling by TGFβ1 in GBM significantly inhibited cell growth and increased apoptosis. Moreover, application of active AR ligand 5α-dihydrotestosterone (DHT) significantly decreased the effect of TGFβ1 on GBM growth and apoptosis, suggesting that AR signaling pathway may contradict the effect of TGFβ receptor signaling in GBM. However, neither total protein nor the phosphorylated protein of SMAD3, a major TGFβ receptor signaling downstream effector in GBM, was affected by DHT, suggesting that AR activation may not affect the SMAD3 protein production or phosphorylation of TGFβ receptor and SMAD3. Finally, immunoprecipitation followed by immunoblot confirmed binding of pAR to pSMAD3, which may prevent the DNA binding of pSMAD3 and subsequently prevent its effect on cell growth in GBM. Taken together, our study suggests that AR signaling may promote tumorigenesis of GBM in adult men by inhibiting TGFβ receptor signaling.

MiR-143 inhibits EGFR-signaling-dependent osteosarcoma invasion

The molecular regulation of the invasion of osteosarcoma (OS) remains elusive. Here, we reported significant lower level of miR-143 and significant levels of phosphorylated EGFR and MMP9 in the resected OS from the patients, compared to the adjacent normal tissue. Moreover, strong correlation was detected among these three factors. We thus hypothesized existence of a causal link, which prompted us to use two human OS cell lines to study the interaction of miR-143, MMP9, and activation of EGFR signaling. We found that EGF-induced EGFR phosphorylation in both lines activated MMP9, and consequently cancer invasiveness. Both an inhibitor for EGFR phosphorylation and an inhibitor for ERK1/2 phosphorylation significantly inhibited the EGF-induced activation of MMP9. Moreover, miR-143 levels did not alter by EGF-induced EGFR phosphorylation, while overexpression of miR-143 antagonized EGF-induced MMP9 activation without affecting EGFR phosphorylation. Taken together, our data suggest that miR-143 inhibits EGFR signaling through its downstream ERK/MAPK signaling cascades to control MMP9 expression in OS. Thus, miR-143, EGFR, and MMP9 are therapeutic targets for inhibiting OS invasion.

MiRNA-181c inhibits EGFR-signaling-dependent MMP9 activation via suppressing Akt phosphorylation in glioblastoma

As the most aggressive malignant primary human brain tumor, glioblastoma is noted with extremely poor patient survival. Previous studies have demonstrated that expression of matrix metalloproteinase-9 (MMP9) in glioblastoma cells is critical for cancer metastasis. However, the molecular signaling pathways that control MMP9 activation remain undefined. Here, we reported a strong negative correlation of microRNA (miRNA)-181c levels with either MMP9 levels or activation of epidermal growth factor receptor (EGFR) signaling in glioblastoma patients. EGF-induced activation of EGFR in a human glioblastoma line, A-172 cells, increased MMP9 expression through activation of phosphatidylinositol 3-kinase (PI3K)/Akt pathway, without affecting expression of miRNA-181c. On the other hand, overexpression of miRNA-181c in A-172 cells inhibited MMP9 expression by inhibiting Akt phosphorylation, but not phosphorylation of EGFR receptor. Taken together, these findings suggest that EGFR signaling activates downstream PI3K/Akt to increase MMP9 expression in glioblastoma, while phosphorylation of Akt is a control point by miRNA-181c. Our work thus provides new insights into the molecular basis underlying the metastasis of glioblastoma.