Expression of p-Akt and COX-2 in Gastric Adenocarcinomas and Adenovirus Mediated Akt1 and COX-2 ShRNA Suppresses SGC-7901 Gastric Adenocarcinoma and U251 Glioma Cell Growth In Vitro and In Vivo

RNAi therapeutics for brain cancer: current advancements in RNAi delivery strategies

Malignant primary brain tumors are aggressive cancerous cells that invade the surrounding tissues of the central nervous system. The current treatment options for malignant brain tumors are limited due to the inability to cross the blood-brain barrier. The advancements in current research has identified and characterized certain molecular markers that are essential for tumor survival, progression, metastasis and angiogenesis. These molecular markers have served as therapeutic targets for the RNAi based therapies, which enable site-specific silencing of the gene responsible for tumor proliferation. However, to bring about therapeutic success, an efficient delivery carrier that can cross the blood-brain barrier and reach the targeted site is essential. The current review focuses on the potential of targeted, non-viral and viral particles containing RNAi therapeutic molecules as delivery strategies specifically for brain tumors.

Blockade of CXCR6 reduces invasive potential of gastric cancer cells through inhibition of AKT signaling

Chemokines and their receptors have been implicated in cell migration and metastasis of multiple malignant tumors. But the function of CXCR6 signaling in gastric cancer is not comprehensively understood. In the present study, we hypothesized that CXCR6 signaling might play an essential role in the progression of gastric cancer. The expression of CXCR6 was examined by immunohistochemical assay in human gastric cancer, and lentivirus-mediated CXCR6 knockdown by shRNA (Lv-shCXCR6) was used for investigating cell migration and invasion indicated by Wound-healing and Transwell assays. Consequently, the expression level of CXCR6 was increased in gastric cancer compared with the adjacent non-tumor tissues (54.2% vs. 27.1%, P = 0.006), and was closely associated with the metastatic lymph node in gastric cancer (P = 0.021). Furthermore, blockade of the CXCR6 signaling reduced the migration and invasion of gastric cancer cells followed by decreased expression of AKT, MMP-2, and MMP-9. In conclusion, these findings demonstrate that CXCR6 may promote the development of gastric cancer cells through regulation of AKT signaling.

MMP-7 is upregulated by COX-2 and promotes proliferation and invasion of lung adenocarcinoma cells

Matrix metalloproteinases (MMPs) have been implicated in a variety of pathophysiological conditions, of which MMP-7 is expressed by tumor cells of epithelial and mesenchymal origin. However, the function of MMP-7 in human lung adenocarcinoma (LAC) is unclear. In the present study the expression of MMP-7 in LAC was examined by immunohistochemical assay using a tissue microarray procedure. A loss-of-function experiment was performed to explore the effects and molecular mechanisms of lentiviral vector-mediated MMP-7 siRNA (siMMP-7) on cell proliferation and invasive potential in LAC A549 cells, measured by MTT and Transwell assays, respectively. It was found that, the expression of MMP-7 protein in LAC was significantly increased compared with that in adjacent non-cancerous tissues (ANCT) (76.0% vs 44.0%, P<0.001), and positively correlated with lymph node metastases of the tumor (P=0.014). Furthermore, targeted inhibition of cyclooxygenase-2 (COX-2) by siRNA downregulated the expression of MMP-7 and inhibited invasion of LAC cells, and knockdown of MMP-7 suppressed tumor proliferation and invasion in LAC cells. Taken together, our findings indicate that increased expression of MMP-7 is associated with lymph node metastasis and upregulated by COX-2, and promotes the tumorigenesis of LAC, suggesting that MMP-7 may be a potential therapeutic target for the treatment of cancer.

Distinct roles of Akt1 in regulating proliferation, migration and invasion in HepG2 and HCT 116 cells

Elucidating the effects of genes involved in tumors may improve therapeutic strategies for human cancer. Recently, several studies discovered that Akt1 plays a dual role in mediating cell proliferation, migration and invasion, depending on the cell type. However, the pathophysiological role of Akt1 in hepatocellular carcinoma (HCC) and colorectal carcinoma cells remains poorly understood. In the present study, we transfected the Akt1-expressing plasmids into the tumor cells that expressed only low levels of Akt1. The migration and invasion abilities were analyzed in 24-well Boyden chambers. The expression of proteins was detected using western blot analysis. Our results demonstrated that overexpression of Akt1 significantly enhanced the proliferation rates and promoted the colony formation in both HepG2 and HCT 116 cells. When treated with wortmannin, the ability to form colonies was significantly attenuated in both cell lines. Of note, enforced expression of Akt1 induced HepG2 cell migration and invasion; by contrast, upregulation of Akt1 expression suppressed the migration and invasion of HCT 116 cells. Subsequent mechanistic investigations revealed that upregulation of Akt1 markedly induced the expression of Bcl-2 and NF-κB in both types of tumor cells. Notably, we observed a similar increase of MMP2, MMP9, HIF1α and VEGF in HCC cells, whereas Akt1 significantly suppressed the expression of these molecules in colorectal carcinoma cells. These data suggest a dual role for Akt1 in tumor cell migration and invasion and highlight the cell type-specific actions of Akt1 kinases in the regulation of cell motility.

Enhancing the Therapeutic Effects of Ethyl Pyruvate on Gastric Cancer through Knockdown of YAP1 Expression

Yes-associated protein (YAP) plays a critical role in tumor formation and malignancy of many cancers and has been shown to be the important therapeutic target. Ethyl pyruvate (EP), a stable lipophilic pyruvate derivative, is a potent inhibitor of high mobility group box-B1 (HMGB1) release and exerts significant anti-inflammatory activities. Previously, we reported the high expression of YAP1 and the antitumor effects of EP in gastric cancer (GC). However, whether small hairpin RNA (shRNA)-mediated knockdown of YAP1 expression enhances the antitumor effects of EP on GC is elusive. After GC SGC-7901 cells infected with lentivirus-mediated YAP1 shRNA vector were treated with 20mmol/L EP, the expression levels of HMGB1, receptor for advanced glycation endproducts (RAGE) and Protein kinase B (AKT) were identified by Real-time PCR and Western blot assays. Cell proliferative activities and independent growth were examined by MTT and colony formation assays, and their migration and metastasis were evaluated by wound-healing and Transwell assays. Cell apoptosis and cycle distribution were assessed by flow cytometry. As a result, EP coupled with YAP1 shRNA significantly decreased the expression levels of HMGB1, RAGE and AKT, inhibited the proliferative activities and migration and metastasis capabilities, and induced apoptosis and cycle arrest in GC cells compared with the single EP treatment. Taken together, knockdown of YAP1 enhances the inhibitory effects of EPon GC cells through inhibition of the HMGB1-RAGE and AKT pathways, and this may provide an attractive strategy for the treatment of GC.

Knockdown of AXL receptor tyrosine kinase in osteosarcoma cells leads to decreased proliferation and increased apoptosis

Dysregulation of the Axl receptor tyrosine kinase (RTK) has been implicated in the development and progression of a variety of malignancies. Axl is known to activate strong anti-apoptotic signaling pathways that promote oncogenesis. However, the role of Axl plays in osteosarcoma (OS) remains elusive. The present study aimed to investigate the clinical significance and function of Axl in human OS. Forty cases of OS and corresponding adjacent non-cancerous tissues (ANCT) were collected. The expression of Axl was assessed using immunohistochemical assay through tissue microarray procedure. A loss-of-function experiment was performed to investigate the effects of small hairpin RNA (shRNA)-mediated knockdown of Axl on the expression of p-AKT, poly ADP-ribose polymerase (PARP) and Ki-67, the proliferative activities, indicated by MTT assay, and the apoptotic index in OS MG-63 cells. As a result, the expression of Axl was found in OS tissues with higher strong reactivity rate, compared with the ANCT (75.0 percent vs 20.0 percent, P=0.000), but it did not associate with the age, gender, tumor size, TNM staging and distant metastases (each Pgreater than0.05). Furthermore, knockdown of Axl inhibited the proliferative activities and induced apoptosis in MG-63 cells with decreased expression of p-AKT, and Ki-67 and increased expression of PARP. In conclusion, our findings suggest that Axl is highly expressed in most of the OS tissues compared with the ANCT, and knockdown of Axl inhibits proliferation and induces apoptosis of OS cells possibly through downregulation of the AKT pathway, suggesting that our findings may provide new insights into the potential therapeutic target for cancer.

Expression of PI3K/AKT pathway in gastric cancer and its blockade suppresses tumor growth and metastasis

Phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway plays a crucial role in the formation and progression of many malignancies, and has been shown to be an important therapeutic target for cancer. In the present study, human gastric adenocarcinoma tissues of different grades (N=45) were collected. The protein expression of PI3Kp85α and phosphorylated AKT (p-AKT) was evaluated immunohistochemically in the biopsy samples. PI3K/AKT pathway was blocked by constructed recombinant small hairpin RNA adenovirus vector rAd5-PI3Kp85α (rAd5-P) used to transfect into human gastric cancer SGC-7901cell line. The transfection efficiency of rAd5-P in SGC-7901 cells was observed under fluorescent microscope. The expression of PI3Kp85α, p-AKT, Ki-67 and matrix metallopeptidase-2 (MMP-2) was detected by real-time PCR and Western blot assays. Cell proliferative activities and metastatic capabilities were determined by MTT and Transwell assays. As a consequence, the protein expression of PI3Kp85α and p-AKT was respectively observed in 80.0% and 82.2% gastric adenocarcinoma tissues, elevating with the ascending order of tumor malignancy. Targeted blockade of PI3K pathway decreased the expression of PI3Kp85α, p-AKT, Ki-67 and MMP-2, and inhibited the proliferative activities and metastatic capabilities of gastric cancer cells. In conclusion, PI3Kp85α and p-AKT were strongly expressed in gastric adenocarcinoma tissues, and targeted blockade of PI3K pathway may inhibit gastric cancer growth and metastasis through down-regulation of Ki-67 and MMP-2 expression. PI3K/AKT pathway may represent an important therapeutic target for gastric cancer.

Expression and clinical significance of HMGB1 in human liver cancer: Knockdown inhibits tumor growth and metastasis in vitro and in vivo

The high-mobility group box 1 (HMGB1) signaling pathway plays a crucial role in tumorigenesis and progression of many malignant cancers. The present study aimed to investigate the expression and clinical significance of HMGB1 in human primary liver cancer, and further explore the molecular mechanisms of HMGB1 in tumor growth and metastasis. Forty cases of human liver cancer and normal liver tissues were collected. The expression of HMGB1 was assessed using RT-PCR and western blot assays in biopsy samples. The HMGB1 pathway in vitro was blocked using transfection of the recombinant small hairpin RNA adenovirus vector rAd5-HMGB1 into the human liver cancer cell line SMMC-7721. The expression of HMGB1, phosphorylated AKT (p-AKT), Ki-67 and matrix metallopeptidase-2 (MMP-2) was detected by Real-PCR and western blot assays. Cell proliferative activities and metastatic capability were determined by MTT and Transwell assays. Cell cycle distribution and apoptosis were detected by flow cytometry. A subcutaneous xenograft tumor model was established, validating the effects of rAd5-HMGB1 on tumor growth in vivo. As a consequence, HMGB1 was found to be highly expressed in liver cancer compared with normal tissues, and was positively associated with pathological grade and distant metastases of liver cancer. Knockdown of HMGB1 downregulated the expression of p-AKT, Ki-67 and MMP-2, inhibited the proliferative activities and metastatic potential of SMMC-7721 cells, induced cell cycle arrest and apoptosis, and slowed the growth of xenograft tumors. Altogether, the expression of HMGB1 is closely correlated with pathological grade and distant metastases of liver cancer, and knockdown of HMGB1 inhibits liver cancer growth and metastasis, suggesting that HMGB1 may be involved in liver cancer development and progression through AKT-mediated regulation of Ki-67 and MMP-2 expression, and represent a potential therapeutic target for this aggressive malignancy.

Microrna-149 Inhibits Proliferation and Invasion of Glioma Cells via Blockade of Akt1 Signaling

MicroRNAs (miRNAs) play important roles in the regulation of gene expressions. Aberrant expression of miRNAs is implicated in a variety of biological and pathological processes, including the tumorigenesis of glioma (GM). Though the molecular mechanisms of protein kinase B (AKT) survival signal have been comprehensively explored, the role of miR-149 in glioblastoma (GBM) and its regulation on AKT signaling have not yet been ascertained. The present study aimed to elucidate the role and molecular mechanisms of miR-149 in U251 GM cells. Using a gain-of-function approach, we investigated the effects of lentivirus-mediated overexpression of miR-149 on the expression of phosphated-AKT1 (p-AKT1), proliferating cell nuclear antigen (PCNA), matrix metallopeptidase-2 (MMP-2) and CyclinD1 in U251 cells and nude mice subcutaneous xenograft tumors by Real-time PCR, Western blot and immunohistochemical assays. Proliferative activities indicated by MTT assay, invasive potential by Transwell and cycle distribution by flow cytometry were carried out for functional analysis of U251 cells after infection with miR-149 mimic. As a consequence, miR-149 inhibited the expression of p-AKT1, PCNA, CyclinD1 and MMP-2, reduced the proliferative activities and invasive potential, and induced cycle arrest in G0/G1 phase in U251 cells. In conclusion, our findings show that miR-149 as tumor suppressor may be involved in the proliferation and invasion of GM cells via blockade of the AKT1 signaling, and be considered as a candidate target for the treatment of cancer.

Anti-angiogenesis by lentivirus-mediated small interfering RNA silencing of angiopoietin-2 gene in pancreatic carcinoma

Angiopoietin-2 (Ang2) has been shown highly expressed in resected human pancreatic carcinoma samples, but the role of it is less clear. We were, therefore, interested in exploring the effects of Ang2 silencing on the angiogenesis and growth of pancreatic carcinoma. Lentivirus mediated Ang2 small hairpin RNA (LV-RNAi) were transfected into pancreatic carcinoma cell line MIA PaCa-2. Three groups were designed in this study: the control group (Mia PaCa-2 cells), the LV-NC group (cells transfected with the control GFP-lentivirus) and the LV-RNAi group (cells transfected with LV-RNAi). The mRNA and protein level of Ang2 gene were detected by real-time polymerase chain reaction and Western blot respectively. MTT assay and Flow Cytometry were used to detect the cell growth and apoptosis. Anti-angiogenesis effect was measured by chick embryo chorioallantoic membrane (CAM) assay. In nude mice bearing tumors, after treatment with intratumoral injection of LV-RNAi, mice growth and tumor volume were observed, and the expression of Ang2, VEGF and CD34 were measured by immunohistochemistry. Compared with the control group and the LV-NC group, the mRNA and protein level of Ang2 gene were successfully knocked down in LV- RNAi group. Also the vessel count was decreased in CAM assay after LV-RNAi transfection. Meanwhile, no obvious cell viability and apoptosis changes were found in MTT assay and Flow Cytometry, respectively. LV-RNAi inhibited pancreatic carcinoma angio- genesis and growth by downregulating the expression of VEGF and CD34. These findings demonstrate that Ang2 gene silencing may exert a anti-angiogenesis effect in vitro and in vivo, and Ang2 targeted gene therapy has the potential to serve as a novel way for pancreatic carcinoma treatment.