PDCD4 Knockdown Induces Senescence in Hepatoma Cells by Up-Regulating the p21 Expression

The Impact of Pdcd4, a Translation Inhibitor, on Drug Resistance

Programmed cell death 4 (Pdcd4) is a tumor suppressor, which has been demonstrated to efficiently suppress tumorigenesis. Biochemically, Pdcd4 binds with translation initiation factor 4A and represses protein translation. Beyond its role in tumor suppression, growing evidence suggests that Pdcd4 enhances the chemosensitivity of several anticancer drugs. To date, numerous translational targets of Pdcd4 have been identified. These targets govern important signal transduction pathways, and their attenuation may improve chemosensitivity or overcome drug resistance. This review will discuss the signal transduction pathways regulated by Pdcd4 and the potential mechanisms through which Pdcd4 enhances chemosensitivity or counteracts drug resistance.

Discovery of ganoderic acid A (GAA) PROTACs as MDM2 protein degraders for the treatment of breast cancer

Breast cancer is one of the most common female malignant tumors, with triple-negative breast cancer (TNBC) being the most specific, highly invasive, metastatic and associated with a poor prognosis. Our previous study showed that the natural product ganoderic acid A (GAA) has a certain affinity for MDM2. In this study, two series of novel GAA PROTACs C1-C10 and V1-V10 were designed and synthesized for the treatment of breast cancer. The antitumor activity of these compounds was evaluated against four human tumor cell lines (MCF-7, MDA-MB-231, SJSA-1, and HepG2). Among them, V9 and V10 showed stronger anti-proliferative effects against breast cancer cells, and V10 showed the best selectivity in MDA-MB-231 cells (TNBC), which was 5-fold higher than that of the lead compound GAA. Preliminary structure-activity analysis revealed that V-series GAA PROTACs had better effects than C-series, and the introduction of 2O-4O PEG linkers could significantly improve the antitumor activity. Molecular docking, surface plasmon resonance (SPR), cellular thermal shift assay (CETSA), and Western blot researches showed that both V9 and V10 could bind with MDM2, and degrade the protein through the ubiquitin-proteasome system. Molecular dynamics simulation (MD) revealed that V10 is a bifunctional molecule that can bind to von Hippel-Lindau (VHL) at one end and target MDM2 at the other. In addition, V10 promoted the upregulation of p21 in p53-mutant MDA-MB-231 cells, and induced apoptosis via down-regulation of the bcl-2/bax ratio and the expression of cyclin B1. Finally, in vivo experiments showed that, V10 also exhibited good tumor inhibitory activity in xenografted TNBC zebrafish models, with an inhibition rate of 27.2% at 50 μg/mL. In conclusion, our results suggested that V10 has anti-tumor effects on p53-mutant breast cancer in vitro and in vivo, and may be used as a novel lead compound for the future development of TNBC.

High fat diet-induced downregulation of TRPV2 mediates hepatic steatosis via p21 signalling

The global prevalence and incidence of non-alcoholic fatty liver disease (NAFLD) are exhibiting an increasing trend. NAFLD is characterized by a significant accumulation of lipids, though its underlying mechanism is still unknown. Here we report that high-fat diet (HFD) feeding induced hepatic steatosis in mice, which was accompanied by a reduction in the expression and function of hepatic TRPV2. Moreover, conditional knockout of TRPV2 in hepatocytes exacerbated HFD-induced hepatic steatosis. In an in vitro model of NAFLD, TRPV2 regulated lipid accumulation in HepG2 cells, and TRPV2 activation inhibited the expression of the cellular senescence markers p21 and p16, all of which were mediated by AMPK phosphorylation. Finally, we found that administration of probenecid, a TRPV2 agonist, impaired HFD-induced hepatic steatosis and suppressed HFD-induced elevation in p21 and p16. Collectively, our findings imply that hepatic TRPV2 protects against the accumulation of lipids by modulating p21 signalling.

Programmed cell death 4: A novel player in the pathogenesis of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a pathological condition recognized by menstrual cycle irregularities, androgen excess, and polycystic ovarian morphology, affecting a significant proportion of women of childbearing age and accounting for the most prevalent cause of anovulatory sterility. In addition, PCOS is frequently accompanied by metabolic and endocrine disturbances such as obesity, dyslipidemia, insulin resistance, and hyperinsulinemia, indicating the multiplicity of mechanisms implicated in the progression of PCOS. However, the exact pathogenesis of PCOS is yet to be elucidated. Programmed cell death 4 (PDCD4) is a ubiquitously expressed protein that contributes to the regulation of various cellular processes, including gene expression, cell cycle progression, proliferation, and apoptosis. Despite some disparities concerning its exact cellular effects, PDCD4 is generally characterized as a protein that inhibits cell cycle progression and proliferation and instead drives the cell into apoptosis. The apoptosis of granulosa cells (GCs) is speculated to take a major part in the occurrence and progression of PCOS by ceasing antral follicle development and compromising oocyte competence. Given the possible involvement of GC apoptosis in the progression of PCOS, as well as the contribution of PDCD4 to the regulation of cell apoptosis and the development of metabolic diseases, the current review aimed to discuss whether or how PDCD4 can play a role in the pathogenesis of PCOS by affecting GC apoptosis.

Human Bone Marrow Mesenchymal Stem Cells-Derived Exosomal miRNA-21-5p Inhibits Lidocaine-Induced Apoptosis in SH-SY5Y Neuroblastoma Cells

Background

Local anesthetic lidocaine is one of the most common pain therapies, but high concentration of lidocaine induced neurotoxicity and its mechanism is unclear. Exosomal microRNAs (miRNAs) is implicated in neuronal diseases, but its role in lidocaine induced neurotoxicity remains to be elucidated.

Methods

All the experiments were performed at Huzhou Key Laboratory of Molecular Medicine, Huzhou City, Jiangsu Province, China in 2022. Lidocaine was used to induce apoptosis of SH-SY5Y cells. Exosomes isolated from bone marrow mesenchymal stem cells (BMSC-exos) were used to co-treat SH-SY5Y cells with lidocaine. Cell apoptosis was measured using a flow cytometer. PKH-67 Dye was used for exosome uptake assay. miR-21-5p mimics/inhibitors, or negative controls were transfected with Lipo2000 to study its effect on lid-induced injury. Interactions between miR-21-5p and PDCD4 was analyzed by luciferase reporter assay.

Results

Administration of BMSC-exo protected SH-SY5Y cells against lidocaine induced apoptosis. Suppressing miR-21-5p dramatically enhanced PDCD4, but miR-21-5p overexpression sharply down-regulated PDCD4. Mechanism study showed that miR-21-5p bound to 3'-UTR of PDCD4 to inhibit it. Suppressing miR-21-5p reversed the effect of BMSC-exo on Lid-induced injury. Results also indicate that miR-21-5p regulated lidocaine-induced injury through targeting PDCD4.

Conclusion

BMSC-exos protected SH-SY5Y cells against lidocaine induced apoptosis through miR-21-5p by targeting PDCD4, which may develop new strategy in the management of lidocaine-induced neurotoxicity.

Upregulated Blood miR-150-5p in Alzheimer’s Disease Dementia Is Associated with Cognition, Cerebrospinal Fluid Amyloid-β, and Cerebral Atrophy

Background: There is an urgent need for noninvasive, cost-effective biomarkers for Alzheimer’s disease (AD), such as blood-based biomarkers. They will not only support the clinical diagnosis of dementia but also allow for timely pharmacological and nonpharmacological interventions and evaluations. Objective: To identify and validate a novel blood-based microRNA biomarker for dementia of the Alzheimer’s type (DAT). Methods: We conducted microRNA sequencing using peripheral blood mononuclear cells isolated from a discovery cohort and validated the identified miRNAs in an independent cohort and AD postmortem tissues. miRNA correlations with AD pathology and AD clinical-radiological imaging were conducted. We also performed bioinformatics and cell-based assay to identify miRNA target genes. Results: We found that miR-150-5p expression was significantly upregulated in DAT compared to mild cognitive impairment and healthy subjects. Upregulation of miR-150-5p was observed in AD hippocampus. We further found that higher miR-150-5p levels were correlated with the clinical measures of DAT, including lower global cognitive scores, lower CSF Aβ 42, and higher CSF total tau. Interestingly, we observed that higher miR-150-5p levels were associated with MRI brain volumes within the default mode and executive control networks, two key networks implicated in AD. Furthermore, pathway analysis identified the targets of miR-150-5p to be enriched in the Wnt signaling pathway, including programmed cell death 4 (PDCD4). We found that PDCD4 was downregulated in DAT blood and was downregulated by miR-150-5p at both the transcriptional and protein levels Conclusion: Our findings demonstrated that miR-150-5p is a promising clinical blood-based biomarker for DAT

Proteomic Analysis of Hypoxia-Induced Senescence of Human Bone Marrow Mesenchymal Stem Cells

Methods

Hypoxia in hBMSCs was induced for 0, 4, and 12 hours, and cellular senescence was evaluated by senescence-associated β-galactosidase (SA-β-gal) staining. Tandem mass tag (TMT) labeling was combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for differential proteomic analysis of hypoxia in hBMSCs. Parallel reaction monitoring (PRM) analysis was used to validate the candidate proteins. Verifications of signaling pathways were evaluated by western blotting. Cell apoptosis was evaluated using Annexin V/7-AAD staining by flow cytometry. The production of reactive oxygen species (ROS) was detected by the fluorescent probe 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA).

Results

Cell senescence detected by SA-β-gal activity was higher in the 12-hour hypoxia-induced group. TMT analysis of 12-hour hypoxia-induced cells identified over 6000 proteins, including 686 differentially expressed proteins. Based on biological pathway analysis, we found that the senescence-associated proteins were predominantly enriched in the cancer pathways, PI3K-Akt pathway, and cellular senescence signaling pathways. CDK1, CDK2, and CCND1 were important nodes in PPI analyses. Moreover, the CCND1, UQCRH, and COX7C expressions were verified by PRM. Hypoxia induction for 12 hours in hBMSCs reduced CCND1 expression but promoted ROS production and cell apoptosis. Such effects were markedly reduced by the PI3K agonist, 740 Y-P, and attenuated by LY294002.

Conclusions

Hypoxia of hBMSCs inhibited CCND1 expression but promoted ROS production and cell apoptosis through activating the PI3K-dependent signaling pathway. These findings provided a detailed characterization of the proteomic profiles related to hypoxia-induced senescence of hBMSCs and facilitated our understanding of the molecular mechanisms leading to stem cell senescence.

Zinc Oxide Nanoparticles Can Intervene in Radiation-Induced Senescence and Eradicate Residual Tumor Cells

Despite recent advancements in tumor therapy, metastasis and tumor relapse remain major complications hindering the complete recovery of many cancer patients. Dormant tumor cells, which reside in the body, possess the ability to re-enter the cell cycle after therapy. This phenomenon has been attributed to therapy-induced senescence. We show that these cells could be targeted by the use of zinc oxide nanoparticles (ZnO NPs). In the present study, the properties of tumor cells after survival of 16 Gy gamma-irradiation were investigated in detail. Analysis of morphological features, proliferation, cell cycle distribution, and protein expression revealed classical hallmarks of senescent cells among the remnant cell mass after irradiation. The observed radiation-induced senescence was associated with the increased ability to withstand further irradiation. Additionally, tumor cells were able to re-enter the cell cycle and proliferate again after weeks. Treatment with ZnO NPs was evaluated as a therapeutical approach to target senescent cells. ZnO NPs were suitable to induce cell death in senescent, irradiation-resistant tumor cells. Our findings underline the pathophysiological relevance of remnant tumor cells that survived first-line radiotherapy. Additionally, we highlight the therapeutic potential of ZnO NPs for targeting senescent tumor cells.

Differential effects of cisplatin combined with the flavonoid apigenin on HepG2, Hep3B, and Huh7 liver cancer cell lines

The potential of apigenin (APG) to enhance cisplatin's (CDDP) chemotherapeutic efficacy was investigated in HepG2, Hep3B, and Huh7 liver cancer cell lines. The presence of 20 μM APG sensitized all cell lines to CDDP treatment (degree of sensitization based on the MTT assay: HepG2>Huh7>Hep3B). As reflected by sister chromatid exchange levels, the degree of genetic instability as well as DNA repair by homologous recombination differed among cell lines. CDDP and 20 μM APG cotreatment exhibited a synergistic genotoxic effect on Hep3B cells and a less than additive effect on HepG2 and Huh7 cells. Cell cycle delays were noticed during the first mitotic division in Hep3B and Huh7 cells and the second mitotic division in HepG2 cells. CDDP and CDDP + APG treatments reduced the clonogenic capacity of all cell lines; however, there was a discordance in drug sensitivity compared with the MMT assay. Furthermore, a senescence-like phenotype was induced, especially in Hep3B and Huh7 cells. Unlike CDDP monotherapy, the combined treatment exhibited a significant anti-invasive and anti-migratory action in all cancer cell lines. The fact that the three liver cancer cell lines responded differently, yet positively, to CDDP + APG cotreatment could be attributed to variations they present in gene expression. Complex mechanisms seem to influence cellular responses and cell fate.

Programmed cell death factor 4 (PDCD4), a novel therapy target for metabolic diseases besides cancer

Programmed cell death factor 4 (PDCD4) is originally described as a tumor suppressor gene that exerts antineoplastic effects by promoting apoptosis and inhibiting tumor cell proliferation, invasion, and metastasis. Several investigations have probed the aberrant expression of PDCD4 with the progression of metabolic diseases, such as polycystic ovary syndrome (PCOS), obesity, diabetes, and atherosclerosis. It has been ascertained that PDCD4 causes glucose and lipid metabolism disorders, insulin resistance, oxidative stress, chronic inflammatory response, and gut flora disorders to regulate the progression of metabolic diseases. This review aims to summarize the latest researches to uncover the structure, expression regulation, and biological functions of PDCD4 and to elucidate the regulatory mechanism of the development of tumors and metabolic diseases. This review has emphasized the understanding of the PDCD4 role and to provide new ideas for the research, diagnosis, and treatment of tumors and metabolic diseases.

PDCD4 controls the G1/S-phase transition in a telomerase-immortalized epithelial cell line and affects the expression level and translation of multiple mRNAs

PDCD4, the protein encoded by the tumor suppressor gene PDCD4 (programmed cell death 4) has been implicated in the control of cellular transcription and translation by modulating the activity of specific transcription factors and suppressing the translation of mRNAs with structured 5′-UTRs. Most studies of human PDCD4 have employed tumor cell lines, possibly resulting in a biased picture of its role in normal cells. Here, we have studied the function of PDCD4 in a telomerase-immortalized human epithelial cell line. We show for the first time that PDCD4 is required for the G1/S-transition, demonstrating its crucial role in the cell cycle. Inhibition of p53-dependent activation of p21^WAF1/CIP1 overrides the requirement for PDCD4 for the G1/S-transition, suggesting that PDCD4 counteracts basal p53 activity to prevent activation of the G1/S checkpoint by p53. Transcriptome and ribosome profiling data show that silencing of PDCD4 changes the expression levels and translation of many mRNAs, providing an unbiased view of the cellular processes that are affected by PDCD4 in an epithelial cell line. Our data identify PDCD4 as a key regulator of cell cycle- and DNA-related functions that are inhibited when it is silenced, suggesting that decreased expression of PDCD4 might contribute to tumor development by compromising genomic integrity.

Growth arrest-specific gene 2 suppresses hepatocarcinogenesis by intervention of cell cycle and p53-dependent apoptosis

BACKGROUND

Growth arrest-specific gene 2 (GAS2) plays a role in modulating in reversible growth arrest cell cycle, apoptosis, and cell survival. GAS2 protein is universally expressed in most normal tissues, particularly in the liver, but is depleted in some tumor tissues. However, the functional mechanisms of GAS2 in hepatocellular carcinoma (HCC) are not fully defined.

AIM

To investigate the function and mechanism of GAS2 in HCC.

METHODS

GAS2 expression in clinic liver and HCC specimens was analyzed by real-time PCR and western blotting. Cell proliferation was analyzed by counting, MTS, and colony formation assays. Cell cycle analysis was performed by flow cytometry. Cell apoptosis was investigated by Annexin V apoptosis assay and western blotting.

RESULTS

GAS2 protein expression was lower in HCC than in normal tissues. Overexpression of GAS2 inhibited the proliferation of HCC cells with wide-type p53, while knockdown of GAS2 promoted the proliferation of hepatocytes (P < 0.05). Furthermore, GAS2 overexpression impeded the G1-to-S cell cycle transition and arrested more G1 cells, particularly the elevation of sub G1 (P < 0.01). Apoptosis induced by GAS2 was dependent on p53, which was increased by etoposide addition. The expression of p53 and apoptosis markers was further enhanced when GAS2 was upregulated, but became diminished upon downregulation of GAS2. In the clinic specimen, GAS2 was downregulated in more than 60% of HCCs. The average fold changes of GAS2 expression in tumor tissues were significantly lower than those in paired non-tumor tissues (P < 0.05).

CONCLUSION

GAS2 plays a vital role in HCC cell proliferation and apoptosis, possibly by regulating the cell cycle and p53-dependent apoptosis pathway.

11PS04 is a new chemical entity identified by microRNA-based biosensing with promising therapeutic potential against cancer stem cells

Phenotypic drug discovery must take advantage of the large amount of clinical data currently available. In this sense, the impact of microRNAs (miRs) on human disease and clinical therapeutic responses is becoming increasingly well documented. Accordingly, it might be possible to use miR-based signatures as phenotypic read-outs of pathological status, for example in cancer. Here, we propose to use the information accumulating regarding the biology of miRs from clinical research in the preclinical arena, adapting it to the use of miR biosensors in the earliest steps of drug screening. Thus, we have used an amperometric dual magnetosensor capable of monitoring a miR-21/miR-205 signature to screen for new drugs that restore these miRs to non-tumorigenic levels in cell models of breast cancer and glioblastoma. In this way we have been able to identify a new chemical entity, 11PS04 ((3aR,7aS)-2-(3-propoxyphenyl)-7,7a-dihydro-3aH-pyrano[3,4-d]oxazol-6(4H)-one), the therapeutic potential of which was suggested in mechanistic assays of disease models, including 3D cell culture (oncospheres) and xenografts. These assays highlighted the potential of this compound to attack cancer stem cells, reducing the growth of breast and glioblastoma tumors in vivo. These data demonstrate the enhanced chain of translatability of this strategy, opening up new perspectives for drug-discovery pipelines and highlighting the potential of miR-based electro-analytical sensors as efficient tools in modern drug discovery.

Control Mechanisms of the Tumor Suppressor PDCD4: Expression and Functions

PDCD4 is a novel tumor suppressor to show multi-functions inhibiting cell growth, tumor invasion, metastasis, and inducing apoptosis. PDCD4 protein binds to the translation initiation factor eIF4A, some transcription factors, and many other factors and modulates the function of the binding partners. PDCD4 downregulation stimulates and PDCD4 upregulation inhibits the TPA-induced transformation of cells. However, PDCD4 gene mutations have not been found in tumor cells but gene expression was post transcriptionally downregulated by micro environmental factors such as growth factors and interleukins. In this review, we focus on the suppression mechanisms of PDCD4 protein that is induced by the tumor promotors EGF and TPA, and in the inflammatory conditions. PDCD4-protein is phosphorylated at 2 serines in the SCF^βTRCP ubiquitin ligase binding sequences via EGF and/or TPA induced signaling pathway, ubiquitinated, by the ubiquitin ligase and degraded in the proteasome system. The PDCD4 protein synthesis is inhibited by microRNAs including miR21.