Inactivation Of Akt Signaling Pathway Research Articles

Absent in melanoma 2 suppresses gastric cancer cell proliferation and migration via inactivation of AKT signaling pathway

Gastric cancer (GC) is the third leading cause of cancer-related mortality worldwide, and poses a great threat to public health. Absent in melanoma 2 (AIM2), a member of the pyrin-HIN family proteins, plays various roles across different types of cancers. However, the possible role of AIM2 in GC, as well as the underling mechanisms, are equivocal and need to be further explored. Herein, we identified that AIM2 expression was significantly down-regulated in GC tissues. Furthermore, loss of AIM2 was significantly associated with tumor size, lymph node metastasis (LNM) and tumor, node, metastases (TNM) staging, as well as poor prognosis in GC patients. Knockdown of AIM2 in GC cells significantly promoted cellular proliferation and migration, whereas AIM2 overexpression did the opposite. Mechanistically, we discovered that AIM2 regulates the AKT signaling pathway. In fact, the enhanced proliferation and migration ability induced by AIM2 knockdown was partially impaired in cells treated with the AKT inhibitor. Overall, our findings suggests that AIM2 is an independent prognostic marker and highlights a new entry point for targeting the AIM2/AKT signaling axis for GC treatment.

MDA19, a novel CB2 agonist, inhibits hepatocellular carcinoma partly through inactivation of AKT signaling pathway

BackgroundCB2 (cannabinoid receptor 2) agonists have been shown to exert anti-tumor activities in different tumor types. However, there is no study exploring the role of MDA19 (a novel CB2 agonist) in tumors. In this study we aimed to investigate the effects of MDA19 treatment on HCC cell lines, Hep3B and HepG2 and determine the relevant mechanisms.ResultsCell proliferation analysis, including CCK8 and colony formation assays, indicated that MDA19 treatment inhibited HCC cell proliferation in a dose- and time-dependent manner. Flow cytometry suggested that MDA19 induced cell apoptosis and activation of mitochondrial apoptosis pathway. Transwell assay indicated that HCC cell migration and invasion were significantly inhibited by MDA19 treatment. Mechanism investigation suggested that MDA19 induced inactivation of AKT signaling pathway in HCC cells. In addition, we investigated the function of CB2receptor in HCC and its role in the anti-tumor activity of MDA19. By searching on Kaplan-Meier plotter (http://kmplot.com/analysis/), we found that HCC patients with high CB2 expression had a better survival and CB2 expression was significantly associated with gender, clinical stages and race of HCC patients (P < 0.05). CB2 inhibited the progression of HCC cells and its knockdown could rescue the growth inhibition induced by MDA19 in HCC. Moreover, the inhibitory effect of MDA19 on AKT signaling pathway was also reversed by CB2 knockdown.ConclusionOur data suggest that MDA-19 exerts an anti-tumor activity at least partly through inactivation of AKT signaling pathway in HCC. CB2 functions as a tumor suppressor gene in HCC, and MDA19-induced growth inhibition of HCC cells depends on its binding to CB2 to activate it. MDA-19 treatment may be a promising strategy for HCC therapy.ReviewerThis article was reviewed by Tito Cali, Mohamed Naguib and Bo Chen.

MCC1019, a selective inhibitor of the Polo-box domain of Polo-like kinase 1 as novel, potent anticancer candidate

Polo-like kinase (PLK1) has been identified as a potential target for cancer treatment. Although a number of small molecules have been investigated as PLK1 inhibitors, many of which showed limited selectivity. PLK1 harbors a regulatory domain, the Polo box domain (PBD), which has a key regulatory function for kinase activity and substrate recognition. We report on 3-bromomethyl-benzofuran-2-carboxylic acid ethyl ester (designated: MCC1019) as selective PLK1 inhibitor targeting PLK1 PBD. Cytotoxicity and fluorescence polarization-based screening were applied to a library of 1162 drug-like compounds to identify potential inhibitors of PLK1 PBD. The activity of compound MC1019 against the PLK1 PBD was confirmed using fluorescence polarization and microscale thermophoresis. This compound exerted specificity towards PLK1 over PLK2 and PLK3. MCC1019 showed cytotoxic activity in a panel of different cancer cell lines. Mechanistic investigations in A549 lung adenocarcinoma cells revealed that MCC1019 induced cell growth inhibition through inactivation of AKT signaling pathway, it also induced prolonged mitotic arrest—a phenomenon known as mitotic catastrophe, which is followed by immediate cell death via apoptosis and necroptosis. MCC1019 significantly inhibited tumor growth in vivo in a murine lung cancer model without affecting body weight or vital organ size, and reduced the growth of metastatic lesions in the lung. We propose MCC1019 as promising anti-cancer drug candidate.

Modified citrus pectin inhibited bladder tumor growth through downregulation of galectin-3.

Modified citrus pectin (MCP) is a carbohydrate enriched complex, which has been implicated in cancer treatment and prevention. However, the effects of MCP on urinary bladder cancer (UBC) are unknown. In this study, MCP was first tested in T24 and J82 human UBC cells and showed the inhibition of cell viability by the sulforhodamine B (SRB) assay. The MCP-treated UBC cells exhibited G2/M phase arrest with the decrease of Cyclin B1 and phosphorylated Cdc2. Caspase-3 was also activated, leading to the cleavage of Caspase-3 and PARP. We further explored the possible molecular mechanisms upon MCP treatment in UBC cells. Reduction of galectin-3 was observed and followed with the inactivation of Akt signaling pathway. Of note, galectin-3 knockdown by RNA interference recapitulated the MCP-mediated anti-proliferation, cell cycle arrest and apoptosis. Moreover, oral administration of MCP to the T24 xenograft-bearing nude mice inhibited the tumor growth significantly (P < 0.05). Quantification analysis of immunohistochemistry staining for Ki67 and cleaved Caspase-3 confirmed the decrease of proliferation index (P < 0.05) and the increase of apoptosis index (P < 0.01) in 700 mg/kg MCP-fed UBC xenografts. Using the information from TCGA database, we revealed that the overexpression of galectin-3 was associated with high tumor grade with lymph node metastasis, poor overall survival in UBC patients. Considering the remarkable inhibitory effects of MCP on UBC cell proliferation and survival in vitro and in vivo mainly through galectin-3, which is upregulated in UBCs, MCP may become an attractive agent, as a natural dietary fiber, for prevention and therapy of UBCs.

Increased expression of insulin‐like growth factor‐1 receptor is correlated with tumor metastasis and prognosis in patients with osteosarcoma

The aim of this study was to investigate the association of insulin-like growth factor-1 receptor (IGF-1R) with metastasis and prognosis of osteosarcoma patients. RT-PCR and Western blot assays were performed to detect IGF-1R mRNA and protein expression in 26 osteosarcoma and noncancerous bone tissues. Immunohistochemistry was performed to analyze the correlation of IGF-1R expression in 84 osteosarcoma tissues with clinicopathological factors or survival of patients. Lentivirus-mediated RNA interference system was employed to downregulate IGF-1R expression and analyze the effects of IGF-1R downregulation on invasion and metastasis of osteosarcoma cells. The relative levels of IGF-1R mRNA and protein expression were significantly higher in osteosarcoma tissues than in corresponding noncancerous bone tissues. The expression of IGF-1R protein was closely associated with surgical stage and distant metastasis of osteosarcoma patients. Osteosarcoma patients with high IGF-1R expression had poorer survival, and multivariate Cox analyses showed that high IGF-1R expression was an independent prognostic maker. Lentivirus-mediated targeting IGF-1R could significantly inhibit adhesion, migration, invasion, and metastasis of osteosarcoma cells, which might be correlated with of inactivation of Akt signaling pathway. IGF-1R is an independent prognostic marker for osteosarcoma patients and increased expression of this molecular is correlated with metastasis of osteosarcoma.

Hydroxytyrosol Induces Vascular Smooth Muscle Cells Apoptosis through NO Production and PP2A Activation with Subsequent Inactivation of Akt

Olive oil has been shown to exhibit beneficial effects in the prevention of cardiovascular diseases although its molecular mechanism still remains unclear. In the present study, we investigated the effect of hydroxytyrosol (HT), a major phenolic component in olive oil and leaves from OLEA EUROPAEA L. (Oleaceae family), on vascular smooth muscle cells (VSMCs) survival, migration, and apoptosis. HT treatment resulted in a dose-dependent decrease of cell survival and migration in the presence or absence of platelet-derived growth factor (PDGF) by inducing apoptosis of VSMCs. HT enhanced nitric oxide (NO) production in a dose-dependent manner, and the NO synthase inhibitor L-NMMA blocked HT-mediated effects on VSMCs survival. HT as well as the NO donor SNAP reduced the phosphorylation levels of Akt, suggesting that HT inactivates Akt via NO production with subsequent apoptosis of VSMCs. Moreover, HT-dependent apoptosis and reduction in the phosphorylation level of Akt were suppressed by okadaic acid, an inhibitor of protein phosphatase 2A (PP2A) that dephosphorylates Akt. In contrast, the phosphorylation of phosphoinositide-dependent protein kinase 1 (PDK1), an upstream activator of Akt, was not affected by HT. Together, these findings indicate that HT could induce VSMCs apoptosis through NO production and PP2A activation followed by inactivation of Akt signaling pathway.

MicroRNA-451 functions as a tumor suppressor in human non-small cell lung cancer by targeting ras-related protein 14 (RAB14)

Accumulating evidence suggests that microRNAs (miRNAs) are important gene regulators, which can have critical roles in diverse biological processes including tumorigenesis. In this study, we analyzed the miRNA expression profiles in non-small cell lung carcinoma (NSCLC) by use of a miRNA microarray platform and identified 40 differentially expressed miRNAs. We showed that miRNA (miR)-451 was the most downregulated in NSCLC tissues. The expression level of miR-451 was found to be significantly correlated with tumor differentiation, pathological stage and lymph-node metastasis. Moreover, low miR-451 expression level was also correlated with shorter overall survival of NSCLC patients (P<0.001). Ectopic miR-451 expression significantly suppressed the in vitro proliferation and colony formation of NSCLC cells and the development of tumors in nude mice by enhancing apoptosis, which might be associated with inactivation of Akt signaling pathway. Interestingly, ectopic miR-451 expression could significantly inhibit RAB14 protein expression and decrease a luciferase-reporter activity containing the RAB14 3'-untranslated region (UTR). In addition,, RNA interference silencing of RAB14 gene could recapitulate the tumor suppressor function of miR-451, whereas restoration of RAB14 expression could partially attenuate the tumor suppressor function of miR-451 in NSCLC cells. Furthermore, we also showed that strong positive immunoreactivity of RAB14 protein was significantly associated with downregulation of miR-451 (P=0.01). These findings suggest that miR-451 regulates survival of NSCLC cells partially through the downregulation of RAB14. Therefore, targeting with the miR-451/RAB14 interaction might serve as a novel therapeutic application to treat NSCLC patients.

Upregulation of microRNA-451 increases cisplatin sensitivity of non-small cell lung cancer cell line (A549)

BackgroundRecently, miR-451 as a tumor suppressor has been reported in other studies. However, whether miR-451 can affect the sensitivity of non-small cell lung cancer (NSCLC) cells to cisplatin (DDP) remains unclear. The aim of this study is to evaluate the roles of miR-451 in the sensitivity of NSCLC cells to DDP.MethodsQuantitative RT-PCR assay was performed to detect the expression of miR-451 in 10 pairs of NSCLC and noncancerous tissue samples. pcDNA-GW/EmGFP-miR-451 was stably transfected into NSCLC cell line (A549). Then, the effects of miR-451 upregulation on growth, colony formation and apoptosis of A549 cells were investigated. Finally, the effects of miR-451 upregulation on in vitro and in vivo sensitivity of A549 cells of DDP were also determined.ResultsThe level of miR-451 expression in NSCLC tissues was significantly higher than that in corresponding noncancerous tissues. Ectopic overexpression of miR-451 could significantly inhibit growth and induce apoptosis of A549 cells. Moreover, ectopic overexpression of miR-451 could sensitize A549 cells to DDP possibly by increasing DDP-induced apoptosis which might be associated with the inactivation of Akt signaling pathway.ConclusionsThis study demonstrated for the first time that combination of DDP application with miR-451 upregulation might be a potential strategy for the treatment of human NSCLC.

Gambogenic acid mediated apoptosis through the mitochondrial oxidative stress and inactivation of Akt signaling pathway in human nasopharyngeal carcinoma CNE-1 cells

In the present study, Gambogenic acid exhibits potential anti-tumor activity in several cancer cell lines. However, Gambogenic acid-induced apoptosis mechanism is not well understood. Here, we report that Gambogenic acid was capable to induce CNE-1 cells apoptosis and caused mitochondrial and endoplasmic reticulum injury, analyzed via transmission electron microscopy and acridine orange/ethidium bromide (AO/EB) double staining. To quantitatively analyze apoptosis, through the propidium iodide (PI)/Annexin V-FITC double staining to detect cell apoptosis, PI staining of the cell cycle distribution. To further explore the potential mechanism of Gambogenic acid mediated apoptosis in CNE-1 cells, we also examined mitochondrial oxidative stress in the levels of reactive oxygen species, the release of cytochrome c, intracellular Ca 2+ concentration and mitochondrial membrane potential by flow cytometry. Moreover, Gambogenic acid could result in a time and concentration-dependent decrease in Phospho-Akt expression, basal expression levels of Akt change was not obvious, In addition, we detected Bcl-2 family including Bcl-2, Bax and Bad expression in mRNA level. This resulted in a decrease of Bcl-2 and Bad increased in CNE-1 cells after Gambogenic acid treatment. Overall, our results indicated that Gambogenic acid mediated apoptosis through inactivation of Akt, accompanied with mitochondrial oxidative stress and cross-talk with Bcl-2 family in the process of apoptosis.

Abstract 5016: Retinoic acid receptor responder 3 expression suppresses colorectal cancer cell growth in vitro and is a stage-independent prognostic marker in colorectal cancer patients in vivo

Abstract Colorectal cancer (CRC) is one of the major causes of cancer death worldwide. Whilst adjuvant chemotherapy can improve survival in Dukes’ C patients, its application on Dukes’ B patients is controversial. Identification of factors that can predict recurrence in the latter group may facilitate classification of high risk patients for receiving adjuvant therapy. Retinoic acid receptor responder 3 (Rarres3) was firstly identified as the retinoid induced class II tumor suppressor in human keratinocytes and psoriatic lesions. In breast, head and neck, lung and gastric cancer cell lines, induced expression of Rarres3 by retinoid can inhibit cell proliferation. Less is known of its effect on colon cancer. Using real-time quantitative RT-PCR, coupled with in vitro functional assays, we have characterized the role of Rarres3 in colorectal cancer development. By comparing the mRNA expression level of Rarres3 in 405 CRCs and 19 colon cancer cell lines with 63 paired normal colons, Rarres3 is down-regulated in most of the CRCs and cell lines. Loss of Rarres3 expression is strongly associated with Dukes’ D patients (p=0.009) and well or moderately differentiated tumor type (p=0.016). Kaplan-Meier analysis demonstrated an improved overall survival (p=0.001) for patients with high expression of Rarres3 by log-rank test. Specifically, there is a prolonged overall survival (p=0.007) and disease free (p=0.012) for Dukes’ B patients (n=158). In multivariate Cox Regression analysis, Rarres3 is an independent factor to predict overall survival (HR=0.473, p=0.001) and disease free (HR=0.557, p=0.047) apart from lymphovascular invasion and Dukes’ stages. Rarres3 protein expression can be induced in colon cancer cell lines by treatment with either interferon-γ (IFNγ) or all-trans retinoic acid (ATRA). Stable transfection of Rarres3 into SW480 colon cancer cells led to inactivation of Akt signaling pathway, suppression of cell growth and enhancement of cell apoptosis via capase-1 activated apoptotic pathway in response to 5-fluorouracil treatment. In addition, we found that Rarres3 is a Wnt target in which its expression is suppressed during Wnt activation and vice versa in colon cancer cell lines. In summary, Rarres3 expression can be induced by IFNγ and ATRA, causing suppression of cell growth and sensitization of cancer cells to apoptosis. Loss of Rarres3 expression in CRCs is predictive of tumor recurrence and poor prognosis especially in Dukes’ B patients, thus aids in molecular stratification of high risk patients. The results also raise the possibility for the use of IFNγ and ATRA in CRC treatment especially in the high risk Dukes’ B subgroup. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5016.