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Protein-level downregulation of eIF4G1 in rapamycin-treated BT-474 cells and in Ly294002-treated SK-BR-3 cells. The breast cancer cells were treated with 100 nM rapamycin and 50 μM Ly294002 for 24 hours and the protein expression of eIF4G1 was detected by Western immunoblotting. The plus (+) sign indicates the inhibitor-treated sample and the minus (-) sign the non-treated sample. A) Rapamycin and B) Ly294002 downregulated eIF4G1 expression at protein level in BT-474 and SK-BR-3 cells, respectively. Beta-actin was used as a loading control.
Source publication
The 70 kDa ribosomal protein S6 kinase (RPS6KB1), located at 17q23, is amplified and overexpressed in 10-30% of primary breast cancers and breast cancer cell lines. p70S6K is a serine/threonine kinase regulated by PI3K/mTOR pathway, which plays a crucial role in control of cell cycle, growth and survival. Our aim was to determine p70S6K and PI3K/mT...
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Citations
... It has been demonstrated that the PI3K/Akt pathway performs a critical function in anti-apoptosis and autophagy (Jiang et al., 2017;Tsuruta et al., 2002;Wang et al., 2022;Yamaguchi and Wang, 2001). Upon activation through phosphoryla-tion, pAkt promotes cell survival by inactivating the pro-apoptotic proteins Bad, c-Raf and caspase-9 (Burgering & Bos, 1995;Cardone et al., 1998;Franke & Cantley, 1997;Zimmermann & Moelling, 1999) and activates mammalian target of rapamycin (mTOR) phosphorylation (Heinonen et al., 2008). mTOR, a serine/threonine kinase, is a critical downstream target of Akt and plays an important role in the regulation of apoptosis (Hay & Sonenberg, 2004;Sussman et al., 2011). ...
Background
Bovine viral diarrhoea virus (BVDV) is an important viral pathogen that has an economic impact on the livestock industry worldwide. Autophagy is one of the earliest cell‐autonomous defence mechanisms against microbial invasion, and many types of viruses can induce autophagy by infecting host cells.
Objectives
The aim of this study was to identify the role of autophagy in the pathogenesis of non‐cytopathic (ncp) BVDV2 infection.
Methods
Madin–Darby bovine kidney (MDBK) cells were treated with ncp BVDV2, rapamycin, or 3‐methyladenine (MA) and ncp BVDV2 and then incubated at 37°C for 24 h. Cells were harvested, and the effects of autophagy were determined by transmission electron microscopy (TEM), confocal laser microscopy, western blotting and qRT‐PCR. Apoptotic analysis was also performed using western blotting and flow cytometry.
Results
In ncp BVDV2‐infected MDBK cells, more autophagosomes were observed by TEM, and the number of microtubule‐associated protein 1 light chain 3B (LC3B) with green fluorescent protein puncta was also increased. The ncp BVDV2‐infected cells showed significantly enhanced conversion of LC3‐I to LC3‐II, as well as upregulation of autophagy‐related proteins, including ATG5 and Beclin 1, and substantial degradation of p62/SQSTM1. These results are similar to those induced by rapamycin, an autophagy inducer. E2 protein expression, which is associated with viral replication, increased over time in ncp BVDV2‐infected cells. Inhibition of autophagy by 3‐MA in ncp BVDV2‐infected MDBK cells downregulated the expressions of LC3‐II, ATG5 and Beclin 1 and prevented the degradation of p62/SQSTM1. Moreover, the expressions of phosphorylated Akt and procaspase‐3 were significantly increased in ncp BVDV2‐infected cells. In addition, the mRNA level of protein kinase R (PKR) was significantly reduced in ncp BVDV2‐infected cells.
Conclusions
Our results demonstrate that ncp BVDV2 infection induced autophagy in MDBK cells via anti‐apoptosis and PKR suppression. Therefore, autophagy may play a role in establishing persistent infection caused by ncp BVDV.
... HER2 in turn increases the synthesis of vascular endothelial growth factor (VEGF) through the PI3K signaling pathway and activation of mTOR/ribosomal protein S6 kinase beta-1 (p70S6K), leading to increased angiogenesis. Moreover, p70S6K phosphorylates Bad leading to a decrease in apoptosis and an increase in cell survival (Heinonen et al. 2008). Furthermore, RONS have a stabilizing function on hypoxiainducible-factor-1α (HIF-1α), which binds to HIF-1β and induces the transcription of angiogenic factors. ...
... This process is called angiogenesis (Schneider and Miller 2005). As a result, nutrients are transported towards the tumor while waste products are removed, providing an ideal environment for tumor development and tumor growth, eventually resulting in breast cancer (Heinonen et al. 2008;Comito et al. 2011) promote tumor growth by secreting growth factors including TGFβ and VEGF (Houthuijzen and Jonkers 2018;Chen et al. 2019). Cancer-associated fibroblasts are induced by TGFβ, creating an autocrine loop to support their activation. ...
... Both cancer-associated fibroblasts and tumor-associated macrophages support tumor proliferation and growth and are thus associated with a poor prognosis (Legrand et al. 2018;Houthuijzen and Jonkers 2018;Chen et al. 2019). This increases the number of tumor cells even more and eventually breast cancer, which is the AO of this AOP network, is developed (Heinonen et al. 2008;Comito et al. 2011). ...
Adverse outcome pathways (AOPs), introduced in modern toxicology, intend to provide an evidence-based representation of toxicological effects and facilitate safety assessment of chemicals not solely based on laboratory animal in vivo experiments. However, some toxicological processes are too complicated to represent in one AOP. Therefore, AOP networks are developed that help understanding and predicting toxicological processes where complex exposure scenarios interact and lead to the emergence of the adverse outcome. In this study, we present an AOP network for breast cancer, developed after an in-depth survey of relevant scientific literature. Several molecular initiating events (MIE) were identified and various key events that link the MIEs with breast cancer were described. The AOP was developed according to Organization of Economic Co-Operation and Development (OECD) guidance, weight of evidence was assessed through the Bradford Hill criteria and confidence was tested by the OECD key questions. The AOP network provides a straightforward understanding of the disease onset and progression at different biological levels. It can be used to pinpoint knowledge gaps, identify novel therapeutic targets and act as a stepping stone for the development of novel in vitro test methods for hazard identification and risk assessment of newly developed chemicals and drugs.
... In the mTOR signaling pathway, some genes, including phosphatidylinositol3-kinase (PI3K), protein kinase B (AKT), and phosphatase and tensin homologue (PTEN), play role as triggers for the activation of cell survival, proliferation and cell growth [8]. Therefore, its therapeutic potential against certain cancers, including gastric cancer, non-small cell lung cancer, and breast cancer [8][9][10], has been evaluated. ...
Rapamycin, also known as sirolimus, inhibits the mTOR pathway in complex diseases such as cancer, and its downstream targets are ribosomal S6 kinases (RPS6K). Sirolimus is involved in regulating cell growth and cell survival through roles such as the mediation of epidermal growth factor signaling. However, the systemic efficacy of sirolimus in pathway regulation is unclear. The purpose of this study is to determine systemic drug efficacy using computational methods and drug-induced datasets. We suggest a computational method using gene expression datasets induced by sirolimus and an inverse algorithm that simultaneously identifies parameters referring to gene–gene interactions. We downloaded two sirolimus-induced microarray gene expression datasets and used a computational method to obtain the most enriched pathway, then adopted an inverse algorithm to discover the gene–gene interactions of that pathway. In the results, RPS6KB1 was a target gene of sirolimus and was associated with genes in the pathway. The common gene interactions from two datasets were a hub gene, RPS6KB1, and 10 related genes (AKT3, CBLC, MAP2K7, NRG1/2, PAK3, PIK3CD/G, PRKCG, and SHC3) in the epidermal growth factor (ERBB) signaling pathway.
... pAkt activates the downstream mTOR and make it phosphorylated, which is followed by downregulation of phosphorylated p70S6K. The result induces autophagy [6,13,42,44,45]. To understand the mechanism of deglycosylated EpCAM-mediated autophagy in breast cancer cells, we analyzed the Akt-mTOR signaling pathway. ...
Autophagy is an important regulator of cellular homeostasis and its dysregulation often results in cancer. Aberrant glycosylation induced by oncogenic transformation contributes to tumor invasion and metastasis. In a previous study, we have demonstrated that EpCAM, a glycosylation protein, is associated with cell growth and metastasis in breast cancer. But the effect of EpCAM glycosylation on autophagy is not clear. the precise mechanism of regulation remains largely unknown. In this study, breast cancer cells were transfected with N-glycosylation mutation EpCAM plasmid to express deglycosylated EpCAM. The result showed that deglycosylated EpCAM promoted autophagy in breast cancer cells. We further confirmed this conclusion with the activator (Rapamycin, RAP) and inhibitor (Wortmannin) of autophagy. We also found that deglycosylated EpCAM promoted apoptosis and inhibited proliferation through activating autophagy by suppressing Akt/mTOR signaling pathway in breast cancer cells. These findings represent a novel mechanism by which deglycosylated EpCAM inhibits proliferation by enhancing autophagy of breast cancer cells via PI3K/Akt/mTOR pathway. In conclusion, the combination of autophagy modulation and EpCAM targeted therapy is a promising therapeutic strategy in the treatment of breast cancer.
... RPS6KB1 promotes protein synthesis, cell survival, and growth and regulates the DNA damage response (14)(15)(16)(17). Recently, it has been observed that hyperphosphorylation and/or overexpression of RPS6KB1 is common in many types of cancer, and therefore, it has become a target for anticancer treatments (18,19). RPS6KB1 was shown to be essential for optimal viral infection in CD4 ϩ T cells by CCR5-tropic human immunodeficiency virus type 1 (HIV-1), but direct phosphorylation of an HIV-1 protein was not tested (20). ...
Mumps virus (MuV) caused the most viral meningitis before mass immunization. Unfortunately, MuV has re-emerged in the United States in the past several years. MuV is a member of the family Paramyxoviridae , in the genus Rubulavirus , and has a non-segmented, negative-stranded RNA genome. The viral RNA-dependent RNA polymerase (vRdRps) of MuV consists of the large protein (L) and the phosphoprotein (P), while the nucleocapsid protein (NP) encapsulates the viral RNA genome. These proteins make up the replication and transcription machinery of MuV. The P protein is phosphorylated by host kinases, and its phosphorylation is important for its function. In this study, we performed a large-scale siRNA screen targeting host kinases that regulated MuV replication. The human kinase RPS6KB1 was identified to play a role in MuV replication and transcription. We have validated the role of RPS6KB1 in regulating MuV using siRNA knockdown, an inhibitor, and RPS6KB1 knockout cells. We found that MuV grows better in cells lacking RPS6KB1, indicating that it downregulates viral growth. Furthermore, we detected an interaction between the MuV P protein and RPS6KB1, suggesting that RPS6KB1 directly regulates MuV replication and transcription.
IMPORTANCE Mumps virus is an important human pathogen. In recent years, MuV has reemerged in the United States with outbreaks occurring in young adults who have been vaccinated. Our work provides insight into a previously unknown Mumps virus-host interaction. RPS6KB1 negatively regulates MuV replication, likely through its interaction with the P protein. Understanding viral-host interactions can lead to novel antiviral drugs and enhanced vaccine production.
... The 70-kDa ribosomal P70S6 kinase is a downstream target of the PI3K/mTOR pathway that regulates cell growth and G1 cell cycle progression by inducing the cellular translational machinery (54). P70s6k is commonly upregulated in breast cancer and GBM (55,56). Harada et al (57) demonstrated that the function of p70s6k was not limited to just protein synthesis and growth maintenance. ...
Glioblastoma multiforme (GBM) is an aggressive type of brain tumour that commonly exhibits resistance to treatment. The tumour is highly heterogenous and complex kinomic alterations have been reported leading to dysregulation of signalling pathways. The present study aimed to investigate the novel kinome pathways and to identify potential therapeutic targets in GBM. Meta‑analysis using Oncomine identified 113 upregulated kinases in GBM. RNAi screening was performed on identified kinases using ON‑TARGETplus siRNA library on LN18 and U87MG. Tousled‑like kinase 1 (TLK1), which is a serine/threonine kinase was identified as a potential hit. In vitro functional validation was performed as the role of TLK1 in GBM is unknown. TLK1 knockdown in GBM cells significantly decreased cell viability, clonogenicity, proliferation and induced apoptosis. TLK1 knockdown also chemosensitised the GBM cells to the sublethal dose of temozolomide. The downstream pathways of TLK1 were examined using microarray analysis, which identified the involvement of DNA replication, cell cycle and focal adhesion signalling pathways. In vivo validation of the subcutaneous xenografts of stably transfected sh‑TLK1 U87MG cells demonstrated significantly decreased tumour growth in female BALB/c nude mice. Together, these results suggested that TLK1 may serve a role in GBM survival and may serve as a potential target for glioma.
... Other work revealed that autophagy was stimulated following the phosphorylation of AKT, the activation of mTor phosphorylation, and the repression of p70S6K, while prucalopride was suggested to hinder the initial step. 11,30 Consistent with this, we found that the inhibition of the PI3K/AKT/mTor signaling pathway contributed to autophagy. Specifically, we observed that the downregulation of p-AKT and p-mTor was accompanied by Beclin 1 reduction and the conversion of LC3. ...
Lung cancer is the main cause of cancer incidence and mortality around the world. Prucalopride is an agonist for the 5-hydroxytryptamine 4 receptor, but it was unknown whether prucalopride could be used to treat lung cancer. To investigate the biological effects of prucalopride on proliferation, apoptosis, invasion, and migration of lung cancer cells, and its underlying molecular mechanism in the progression of lung cancer, we performed this study. The Cell Counting Kit 8 assay was used to measure the proliferation of A549/A427 lung cancer cells treated with prucalopride. Transwell assay was applied to evaluate cell invasion and migration. Cell apoptosis was detected by flow cytometry and Western blot analyses. The expression levels of related proteins in the PI3K/AKT/mTor signaling pathway were analyzed by Western blotting. Prucalopride inhibited the proliferation, invasion, and migration of A549/A427 human lung cancer cells. It also induced autophagy and apoptosis and decreased the expression of the phosphorylated protein kinase B (AKT) and mammalian target of rapamycin (mTor) in these cells. This study implied an inhibitory role for prucalopride in the progression of human lung cancer.
... Furthermore, olaparib also reduces proline-rich AKT substrate of 40 kDa (PRAS40), a substrate of AKT. 20 As shown in Figure 6A,B, Western blot analysis confirmed these observations. ...
Background
Poly(adenosine diphosphate ribose) polymerase (PARP) inhibitors exhibit promising activity against ovarian cancers, but their efficacy can be limited by acquired drug resistance. This study explores the role of autophagy in regulating the sensitivity of ovarian cancer cells to PARP inhibitors.
Methods
Induction of autophagy was detected by punctate LC3 fluorescence staining, LC3I to LC3II conversion on Western blot analysis, and electron microscopy. Enhanced growth inhibition and apoptosis were observed when PARP inhibitors were used with hydroxychloroquine, chloroquine (CQ), or LYS05 to block the hydrolysis of proteins and lipids in autophagosomes or with small interfering RNA against ATG5 or ATG7 to prevent the formation of autophagosomes. The preclinical efficacy of the combination of CQ and olaparib was evaluated with a patient‐derived xenograft (PDX) and the OVCAR8 human ovarian cancer cell line.
Results
Four PARP inhibitors (olaparib, niraparib, rucaparib, and talazoparib) induced autophagy in a panel of ovarian cancer cells. Inhibition of autophagy with CQ enhanced the sensitivity of ovarian cancer cells to PARP inhibitors. In vivo, olaparib and CQ produced additive growth inhibition in OVCAR8 xenografts and a PDX. Olaparib inhibited PARP activity, and this led to increased reactive oxygen species (ROS) and an accumulation of γ‐H2AX. Inhibition of autophagy also increased ROS and γ‐H2AX and enhanced the effect of olaparib on both entities. Treatment with olaparib increased phosphorylation of ATM and PTEN while decreasing the phosphorylation of AKT and mTOR and inducing autophagy.
Conclusions
PARP inhibitor–induced autophagy provides an adaptive mechanism of resistance to PARP inhibitors in cancer cells with wild‐type BRCA, and a combination of PARP inhibitors with CQ or other autophagy inhibitors could improve outcomes for patients with ovarian cancer.
... p70S6K, a serine/ threonine kinase, is regulated by the PI3K/mTOR pathway and plays a crucial role in cell cycle, growth and survival. Heinonen et al. found that the silence of p70S6K down-regulated B7-H4 expression in breast cancer cells, suggesting that PI3K pathway may also be involved in B7-H4 expression [153]. ...
The coinhibitory molecule B7-H4, an important member of the B7 family, is abnormally expressed in tumors, inflammation and autoimmune diseases. B7-H4 negatively regulates T cell immune response and promotes immune escape by inhibiting the proliferation, cytokine secretion, and cell cycle of T cells. Moreover, B7-H4 plays an extremely important role in tumorigenesis and tumor development including cell proliferation, invasion, metastasis, anti-apoptosis, etc. In addition, B7-H4 has the other biological functions, such as protection against type 1 diabetes (T1D) and islet cell transplantation. Therefore, B7-H4 has been identified as a novel marker or a therapeutic target for the treatment of tumors, inflammation, autoimmune diseases, and organ transplantation. Here, we summarized the expression profiles, physiological and pathological functions, and regulatory mechanisms of B7-H4, the signaling pathways involved, as well as B7-H4-based immunotherapy.
... In the present study, 20(S)-GRh2 significantly decreased the proliferation rate of Jurkat cells, and combined treatment with 20(S)-GRh2 and PI3K/Akt/mTOR inhibitor further decreased cell proliferation. 4EBP1 and p70S6K, as PI3K/ Akt/mTOR downstream targets, are crucial factors for proliferation in cancer cells [45]. We found that 20(S)-GRh2 combined with the PI3K/Akt/mTOR inhibitor further downregulated the levels of p-4EBP1 and p-p70S6K compared with 20(S)-GRh2 alone, which subsequently inhibited cell proliferation. ...
Background
T-cell acute lymphoblastic leukemia (T-ALL) is a kind of aggressive hematological cancer, and the PI3K/Akt/mTOR signaling pathway is activated in most patients with T-ALL and responsible for poor prognosis. 20(S)-Ginsenoside Rh2 (20(S)-GRh2) is a major active compound extracted from ginseng, which exhibits anti-cancer effects. However, the underlying anticancer mechanisms of 20(S)-GRh2 targeting the PI3K/Akt/mTOR pathway in T-ALL have not been explored.
Methods
Cell growth and cell cycle were determined to investigate the effect of 20(S)-GRh2 on ALL cells. PI3K/Akt/mTOR pathway–related proteins were detected in 20(S)-GRh2–treated Jurkat cells by immunoblotting. Antitumor effect of 20(S)-GRh2 against T-ALL was investigated in xenograft mice. The mechanisms of 20(S)-GRh2 against T-ALL were examined by cell proliferation, apoptosis, and autophagy.
Results
In the present study, the results showed that 20(S)-GRh2 decreased cell growth and arrested cell cycle at the G1 phase in ALL cells. 20(S)-GRh2 induced apoptosis through enhancing reactive oxygen species generation and upregulating apoptosis-related proteins. 20(S)-GRh2 significantly elevated the levels of pEGFP-LC3 and autophagy-related proteins in Jurkat cells. Furthermore, the PI3K/Akt/mTOR signaling pathway was effectively blocked by 20(S)-GRh2. 20(S)-GRh2 suppressed cell proliferation and promoted apoptosis and autophagy by suppressing the PI3K/Akt/mTOR pathway in Jurkat cells. Finally, 20(S)-GRh2 alleviated symptoms of leukemia and reduced the number of white blood cells and CD3 staining in the spleen of xenograft mice, indicating antitumor effects against T-ALL in vivo.
Conclusion
These findings indicate that 20(S)-GRh2 exhibits beneficial effects against T-ALL through the PI3K/Akt/mTOR pathway and could be a natural product of novel target for T-ALL therapy.
