RNAi knockdown of the Akt1 gene increases the chemosensitivity of gastric cancer cells to cisplatin both in vitro and in vivo

siRNA-based strategies to combat drug resistance in gastric cancer

Chemotherapy is a key treatment option for gastric cancer, but over 50% of patients develop either inherent or acquired resistance to these drugs, resulting in a 5-year survival rate of only about 20%. The primary treatment for advanced gastric cancer typically involves chemotherapy based on platinum or fluorouracil. Several factors can contribute to platinum resistance, including decreased drug uptake, increased drug efflux or metabolism, enhanced DNA repair, activation of pro-survival pathways, and inhibition of pro-apoptotic pathways. In recent years, there has been significant progress in biology aimed at finding innovative and more effective methods to overcome chemotherapy resistance. Small interfering RNAs (siRNAs) have emerged as a significant advancement in gene expression regulation, showing promise in enhancing the sensitivity of gastric cancer cells to chemotherapy drugs. However, siRNA therapies still face major challenges, particularly in terms of stability and efficient delivery in vivo. This article discusses the advances in siRNA therapy and its potential role in overcoming resistance to chemotherapeutic drugs such as cisplatin, 5-FU, doxorubicin, and paclitaxel in the treatment of gastric cancer.

Effects of catechin on the malignant biological behavior of gastric cancer cells through the PI3K/Akt signaling pathway

Catechin is a kind of flavonoids, mainly derived from the plant Camellia sinensis. It has a strong antioxidant effect, and it also has significant therapeutic effects on anti-cancer, anti-diabetes, and anti-infection. This study was intended to look at how catechin affected the malignant biological activity of gastric cancer cells. We used databases to predict the targets of catechin and the pathogenic targets of gastric cancer. Venn diagram was used to find the intersection genes, the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analyses were performed on intersection genes. Using the STRING database, the Protein-Protein Interaction (PPI) network was built. The top 8 genes were screened by Cytoscape 3.9.1, then their binding was verified by molecular docking. The proliferation ability, cell cycle, apoptosis and migration of gastric cancer cells were detected, as well as the protein expression levels of PI3K, p-AKT, and AKT and the mRNA expression levels of AKT1, VEGFA, EGFR, HRAS, and HSP90AA1 in gastric cancer cells. Our research revealed that different concentrations of catechin could effectively inhibit the proliferation and migration of gastric cancer cells, regulate the cell cycle, and promote the death of these cells, and it's possible that the PI3K/Akt pathway was crucial in mediating this impact. Moreover, adding the PI3K/Akt pathway agonist significantly reduced the promoting effect of catechin on the apoptosis of gastric cancer cells. This study suggested that catechin was a potential drug for the treatment of gastric cancer.

Semaphorin 4D is a potential biomarker in pediatric leukemia and promotes leukemogenesis by activating PI3K/AKT and ERK signaling pathways

Semaphorin 4D (Sema4D) is highly expressed in a variety of tumors and is associated with high invasion, poor prognosis and poor therapeutic response. However, the expression and role of Sema4D in leukemia remains unclear. The present study investigated the expression of Sema4D in pediatric leukemia and its effects in leukemia cells. The results demonstrated that Sema4D protein was highly expressed in peripheral blood mononuclear cells of patients with pediatric leukemia, and high levels of soluble Sema4D were also observed in the plasma of these patients. Sema4D knockdown induced cell cycle arrest in G₀/G₁ phase, inhibited proliferation and promoted apoptosis in BALL‑1 cells, while Sema4D overexpression exhibited the opposite effect. In Jurkat cells, Sema4D knockdown inhibited proliferation and promoted apoptosis, while Sema4D overexpression decreased the abundance of the cells in the G₀/G₁ phase of the cell cycle and promoted proliferation. Sema4D overexpression also increased the migratory capacity of Jurkat cells and the invasive capacity of BALL‑1 cells. The phosphorylation level of PI3K was decreased in both Sema4D knocked‑down Jurkat and BALL‑1 cells, and the phosphorylation level of ERK was decreased in Sema4D knocked‑down BALL‑1 cells. The phosphorylation levels of PI3K, ERK and AKT were elevated in patients with pediatric leukemia, and were correlated to the increased Sema4D expression. Sema4D overexpression was associated with a shorter overall survival in patients with acute myeloid leukemia. Overall, the results of the present study indicated that Sema4D serves an important role in leukemia development by activating PI3K/AKT and ERK signaling, and it may be used as a potential target for the diagnosis and treatment of leukemia.

Semaphorin 4D is a potential biomarker in pediatric leukemia and promotes leukemogenesis by activating PI3K/AKT and ERK signaling pathways

Semaphorin 4D (Sema4D) is highly expressed in a variety of tumors and is associated with high invasion, poor prognosis and poor therapeutic response. However, the expression and role of Sema4D in leukemia remains unclear. The present study investigated the expression of Sema4D in pediatric leukemia and its effects in leukemia cells. The results demonstrated that Sema4D protein was highly expressed in peripheral blood mononuclear cells of patients with pediatric leukemia, and high levels of soluble Sema4D were also observed in the plasma of these patients. Sema4D knockdown induced cell cycle arrest in G₀/G₁ phase, inhibited proliferation and promoted apoptosis in BALL-1 cells, while Sema4D overexpression exhibited the opposite effect. In Jurkat cells, Sema4D knockdown inhibited proliferation and promoted apoptosis, while Sema4D overexpression decreased the abundance of the cells in the G₀/G₁ phase of the cell cycle and promoted proliferation. Sema4D overexpression also increased the migratory capacity of Jurkat cells and the invasive capacity of BALL-1 cells. The phosphorylation level of PI3K was decreased in both Sema4D knocked-down Jurkat and BALL-1 cells, and the phosphorylation level of ERK was decreased in Sema4D knocked-down BALL-1 cells. The phosphorylation levels of PI3K, ERK and AKT were elevated in patients with pediatric leukemia, and were correlated to the increased Sema4D expression. Sema4D overexpression was associated with a shorter overall survival in patients with acute myeloid leukemia. Overall, the results of the present study indicated that Sema4D serves an important role in leukemia development by activating PI3K/AKT and ERK signaling, and it may be used as a potential target for the diagnosis and treatment of leukemia.

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.

Identification of key genes in rheumatoid arthritis and osteoarthritis based on bioinformatics analysis

Rheumatoid arthritis (RA) and osteoarthritis (OA) comprise the most common forms of arthritis. The aim of this study was to identify differentially expressed genes (DEGs) and associated biological processes between RA and OA using a bioinformatics approach to elucidate their potential pathogenesis.The gene expression profiles of the GSE55457 datasets, originally produced through use of the high-throughput Affymetrix Human Genome U133A Array, were downloaded from the Gene Expression Omnibus (GEO) database. The GSE55457 dataset contains information from 33 samples, including 10 normal control (NC) samples, 13 RA samples, and 10 OA samples. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) enrichment analyses were performed to identify functional categories and associated molecular and biochemical pathways, respectively, for the identified DEGs, and a protein-protein interaction (PPI) network of the DEGs was constructed using Cytoscape software.GO and KEGG results suggested that several biological pathways (ie, "immune response," "inflammation," and "osteoclast differentiation") are commonly involved in the development of both RA and OA, whereas several other pathways (eg, "MAPK signaling pathway," and "ECM-receptor interaction") presented significant differences between these disorders.This study provides further insights into the underlying pathogenesis of RA and OA, which may facilitate the diagnosis and treatment of these diseases.

10H-3,6-Diazaphenothiazine induces G2/M phase cell cycle arrest and caspase-dependent apoptosis and inhibits cell invasion of A2780 ovarian carcinoma cells through the regulation of NF-κB and (BIRC6-XIAP) complexes

The asymptomatic properties and high treatment resistance of ovarian cancer result in poor treatment outcomes and high mortality rates. Although the fundamental chemotherapy provides promising anticancer activities, it is associated with severe side effects. The derivative of phenothiazine, namely, 10H-3,6-diazaphenothiazine (PTZ), was synthesized and reported with ideal anticancer effects in a previous paper. In this study, detailed anticancer properties of PTZ was examined on A2780 ovarian cancer cells by investigating the cytotoxicity profiles, mechanism of apoptosis, and cell invasion. Research outcomes revealed PTZ-induced dose-dependent inhibition on A2780 cancer cells (IC₅₀ =0.62 µM), with significant less cytotoxicity toward HEK293 normal kidney cells and H9C2 normal heart cells. Generation of reactive oxygen species (ROS) and polarization of mitochondrial membrane potential (ΔΨm) suggests PTZ-induced cell death through oxidative damage. The RT² Profiler PCR Array on apoptosis pathway demonstrated PTZ-induced apoptosis via intrinsic (mitochondria-dependent) and extrinsic (cell death receptor-dependent) pathway. Inhibition of NF-κB and subsequent inhibition of (BIRC6-XIAP) complex activities reduced the invasion rate of A2780 cancer cells penetrating through the Matrigel™ Invasion Chamber. Lastly, the cell cycle analysis hypothesizes that the compound is cytostatic and significantly arrests cell proliferation at G₂/M phase. Hence, the exploration of the underlying anticancer mechanism of PTZ suggested its usage as promising chemotherapeutic agent.

Nicotine Inhibits Cisplatin-Induced Apoptosis via Regulating α5-nAChR/AKT Signaling in Human Gastric Cancer Cells

Gastric cancer incidence demonstrates a strong etiologic association with smoking. Nicotine, the major component in tobacco, is a survival agonist that inhibits apoptosis induced by certain chemotherapeutic agents, but the precise mechanisms involved remain largely unknown. Recently studies have indicated that α5-nicotinic acetylcholine receptor (α5-nAChR) is highly associated with lung cancer risk and nicotine dependence. Nevertheless, no information has been available about whether nicotine also affects proliferation of human gastric cancer cells through regulation of α5-nAChR. To evaluate the hypothesis that α5-nAChR may play a role in gastric cancer, we investigated its expression in gastric cancer tissues and cell lines. The expression of α5-nAChR increased in gastric cancer tissue compared with para-carcinoma tissues. In view of the results, we proceeded to investigate whether nicotine inhibits cisplatin-induced apoptosis via regulating α5-nAChR in gastric cancer cell. The results showed that nicotine significantly promoted cell proliferation in a dose and time-dependent manner through α5-nAChR activation in human gastric cells. Furthermore, nicotine inhibited apoptosis induced by cisplatin. Silence of α5-nAChR ablated the protective effects of nicotine. However, when co-administrating LY294002, an inhibitor of PI3K/AKT pathway, an increased apoptosis was observed. This effect correlated with the induction of Bcl-2, Bax, Survivin and Caspase-3 by nicotine in gastric cell lines. These results suggest that exposure to nicotine might negatively impact the apoptotic potential of chemotherapeutic drugs and that α5-nAChR/AKT signaling plays a key role in the anti-apoptotic activity of nicotine induced by cisplatin.

RNA interference: a promising therapy for gastric cancer

Gastric cancer (GC) remains a virtually incurable disease when metastatic and requires early screening tools for detection of early tumor stages. Therefore, finding effective strategies for prevention or recurrence of GC has become a major overall initiative. RNA-interference (RNAi) is an innovative technique that can significantly regulate the expression of oncogenes involved in gastric carcinogenesis, thus constituting a promising epigenetic approach to GC therapy. This review presents recent advances concerning the promising biomolecular mechanism of RNAi for GC treatment.

Adenovirus-mediated LRIG1 expression enhances the chemosensitivity of bladder cancer cells to cisplatin

Cisplatin (cis-diaminodichloroplatinum, CDDP) is one of the most effective chemotherapeutic agents that has been widely used in the treatment of many malignancies, including muscle invasive bladder cancer. However, development of CDDP resistance in cancer cells is a major obstacle to the effective treatment of bladder cancer. Therefore, the development of chemosensitizers to overcome the acquired resistance to chemotherapeutic agents is crucial. Previous studies have confirmed that the epidermal growth factor receptor (EGFR) and its signaling pathways are important in the chemoresistance of cancer cells against CDDP‑induced cell apoptosis. In a preliminary study we showed that leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) is the natural ligand of EGFR, and that the extracellular leucine-rich repeat (LRR) domain and immunoglobulin-like domains of LRIG1 were able to bind to the extracellular domain of EGFR, resulting in the downregulation of EGFR expression. Based on these findings, we hypothesized that LRIG1 may enhance the chemosensitivity of bladder cancer cells to CDDP. In the present study, LRIG1 was overexpressed by the adenovirus vector to determine the effect of LRIG1 on chemosensitivity in the T24 bladder cancer cell line and explored the possible mechanisms. The results showed that CDDP inhibited the growth of the T24 cell line and induced activation of EGFR. Overexpression of LRIG1 increased the inhibitory effect of CDDP on the T24 cell line, which may be associated with inactivation of the EGFR signaling pathway, followed by the decrease of Bcl-2 expression and a concomitantly induced expression of Bax. Based on these results, we concluded that the upregulation of LRIG1 expression inhibited the EGFR signaling pathway, activated the mitochondrial pathway of apoptosis and eventually increased the sensitivity of bladder cancer cells to CDDP.

The Role of PI3K/Akt/mTOR Signaling in Gastric Carcinoma

The phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway is one of the key signaling pathways induced by various receptor-tyrosine kinases. Accumulating evidence shows that this pathway is an important promoter of cell growth, metabolism, survival, metastasis, and resistance to chemotherapy. Genetic alterations in the PI3K/Akt/mTOR pathway in gastric carcinoma have often been demonstrated. Many kinds of molecular targeting therapies are currently undergoing clinical testing in patients with solid tumors. However, with the exception of the ErbB2-targeting antibody, targeting agents, including PI3K/Akt/mTOR inhibitors, have not been approved for treatment of patients with gastric carcinoma. This review summarizes the current knowledge on PI3K/Akt/mTOR signaling in the pathogenesis of gastric carcinoma and the possible therapeutic targets for gastric carcinoma. Improved knowledge of the PI3K/Akt/mTOR pathway in gastric carcinoma will be useful in understanding the mechanisms of tumor development and for identifying ideal targets of anticancer therapy for gastric carcinoma.

Oleanolic acid derivatives induce apoptosis in human leukemia K562 cell involved in inhibition of both Akt1 translocation and pAkt1 expression

Oleanolic acid (OA) derivatives exhibit numerous pleiotropic effects in many cancers. The present study aimed to investigate the molecular mechanisms of 5'-amino-oleana-2,12-dieno[3,2-d]pyrimidin-28-oic acid (compound 4) and oleana-2,12-dieno[2,3-d]isoxazol-28-oic acid (compound 5) inducing apoptosis in human leukemia K562 cell. We investigated the effects of the compounds on K562 cell growth, apoptosis and cell cycle. The compounds showed strong inhibitory effects on K562 cell viability in a dose-dependent manner determined by the 3-(4,5-dimethylthiazoyl)-2,5-diphenyltetrazolium bromide assay and significantly increased chromatin condensation and apoptotic bodies in K562 cells. Flow cytometry assay suggested that the compounds induced inhibition of K562 cell proliferation associated with G1 phase arrest. In addition, the compounds inhibited Akt1 recruiting to membrane in CHO cells which express Akt1-EGFP constitutively and down-regulated the expression of pAkt1 in K562 cell. These results suggested that the compounds can efficiently inhibit proliferation and induce apoptosis perhaps involved in inactivation of Akt1. The OA derivatives may be potential chemotherapeutic agents for the treatment of human cancer.

The novel miR-9500 regulates the proliferation and migration of human lung cancer cells by targeting Akt1

MicroRNAs have crucial roles in lung cancer cell development. They regulate cell growth, proliferation and migration by mediating the expression of tumor suppressor genes and oncogenes. We identified and characterized the novel miR-9500 in human lung cancer cells. The miR-9500 forms a stem-loop structure and is conserved in other mammals. The expression levels of miR-9500 were reduced in lung cancer cells and lung cancer tissues compared with normal tissues, as verified by TaqMan miRNA assays. It was confirmed that the putative target gene, Akt1, was directly suppressed by miR-9500, as demonstrated by a luciferase reporter assay. The miR-9500 significantly repressed the protein expression levels of Akt1, as demonstrated via western blot, but did not affect the corresponding mRNA levels. Akt1 has an important role in lung carcinogenesis, and depletion of Akt1 has been shown to have antiproliferative and anti-migratory effects in previous studies. In the current study, the overexpression of miR-9500 inhibited cell proliferation and the expression of cell cycle-related proteins. Likewise, the overexpression of miR-9500 impeded cell migration in human lung cancer cells. In an in vivo assay, miR-9500 significantly suppressed Fluc expression compared with NC and ASO-miR-9500, suggesting that cell proliferation was inhibited in nude mice. Likewise, miR-9500 repressed tumorigenesis and metastasis by targeting Akt1. These data indicate that miR-9500 might be applicable for lung cancer therapy.

Cell survival and metastasis regulation by Akt signaling in colorectal cancer

Dissemination of cancer cells to distant organ sites is the leading cause of death due to treatment failure in different types of cancer. Mehlen and Puisieux have reviewed the importance of the development of inappropriate cell survival signaling for various steps in the metastatic process and have noted the particular importance of aberrant cell survival to successful colonization at the metastatic site. Therefore, the understanding of mechanisms that govern cell survival fate of these metastatic cells could lead to the understanding of a new paradigm for the control of metastatic potential and could provide the basis for developing novel strategies for the treatment of metastases. Numerous studies have documented the widespread role of Akt in cell survival and metastasis in colorectal cancer, as well as many other types of cancer. Akt acts as a key signaling node that bridges the link between oncogenic receptors to many essential pro-survival cellular functions, and is perhaps the most commonly activated signaling pathway in human cancer. In recent years, Akt2 and Akt3 have emerged as significant contributors to malignancy alongside the well-characterized Akt1 isoform, with distinct non-overlapping functions. This review is aimed at gaining a better understanding of the Akt-driven cell survival mechanisms that contribute to cancer progression and metastasis and the pharmacological inhibitors in clinical trials designed to counter the Akt-driven cell survival responses in cancer.

Role of RNA interference in research of multidrug resistance in gastric cancer

Gastric cancer is one of the most common malignant tumors in the world. Chemotherapy is the main treatment for gastric cancer after operation. However, multidrug resistance of tumor cells always reduces its effectiveness and influences the prognosis of patients directly. For this reason, more and more scientific researchers have been dedicated to the in-depth study of multidrug resistance in gastric cancer. RNA interference allows specific and effective inhibition of the expression of target genes and has been gradually applied to gene treatment for multidrug resistance in gastric cancer. The widespread use of RNA interference in recent years has led to many achievements. This article aims to review the role of RNA interference in research of multidrug resistance in gastric cancer.