Inhibition of HIF1α and PDK Induces Cell Death of Glioblastoma Multiforme

Exploration of the underlying mechanism of Astragaloside III in attenuating immunosuppression via network pharmacology and vitro/vivo pharmacological validation

ETHNOPHARMACOLOGICAL RELEVANCE

Astragalus mongholicus Bunge (AM, recorded in http://www.worldfloraonline.org, 2023-08-03) is a kind of medicine food homology plant with a long medicinal history in China. Astragaloside III (AS-III) has immunomodulatory effects and is one of the most active components in AM. However, its underlying mechanism of action is still not fully explained.

AIM OF THE STUDY

The research was designed to discuss the protective effects of AS-III on immunosuppression and to elucidate its prospective mechanism.

MATERIALS AND METHODS

Molecular docking methods and network pharmacology analysis were used to comprehensively investigate potential targets and relative pathways for AS-III and immunosuppression. In order to study and verify the pharmacological activity and mechanism of AS-III in alleviating immunosuppression, immunosuppression mouse model induced by cyclophosphamide (CTX) in vivo and macrophage RAW264.7 cell model induced by hypoxia/lipopolysaccharide (LPS) in vitro were used.

RESULTS

A total of 105 common targets were obtained from the AS-III-related and immunosuppression-related target networks. The results of network pharmacology and molecular docking demonstrate that AS-III may treat immunosuppression through by regulating glucose metabolism-related pathways such as regulation of lipolysis in adipocytes, carbohydrate digestion and absorption, cGMP-PKG signaling pathway, central carbon metabolism in cancer together with HIF-1 pathway. The results of molecular docking showed that AS-III has good binding relationship with LDHA, AKT1 and HIF1A. In CTX-induced immunosuppressive mouse model, AS-III had a significant protective effect on the reduction of body weight, immune organ index and hematological indices. It can also protect immune organs from damage. In addition, AS-III could significantly improve the expression of key proteins involved in energy metabolism and serum inflammatory factors. To further validate the animal results, an initial inflammatory/immune response model of macrophage RAW264.7 cells was constructed through hypoxia and LPS. AS-III improved the immune function of macrophages, reduced the release of NO, TNF-α, IL-1β, PDHK-1, LDH, lactate, HK, PK and GLUT-1, and restored the decrease of ATP caused by hypoxia. Besides, AS-III was also demonstrated that it could inhibit the increase of HIF-1α, PDHK-1 and LDH by adding inhibitors and agonists.

CONCLUSIONS

In this study, the main targets of AS-III for immunosuppressive therapy were initially analyzed. AS-III was systematically confirmed to attenuates immunosuppressive state through the HIF-1α/PDHK-1 pathway. These findings offer an experimental foundation for the use of AS-III as a potential candidate for the treatment of immunosuppression.

Post-Subfunctionalization Functions of HIF-1αA and HIF-1αB in Cyprinid Fish: Fine-Tuning Mitophagy and Apoptosis Regulation Under Hypoxic Stress

Hypoxia-inducible factor 1 (HIF-1) is a crucial transcriptional factor that can restore oxygen balance in the body by regulating multiple vital activities. Two HIF-1α copies were retained in cyprinid fish after experiencing a teleost-specific genome duplication. How the "divergent collaboration" of HIF-1αA and HIF-1αB proceeds in regulating mitophagy and apoptosis under hypoxic stress in cells of cyprinid fish remains unclear. In this study, zebrafish HIF-1αA/B expression plasmids were constructed and transfected into the epithelioma papulosum cyprini cells and were subjected to hypoxic stress. HIF-1αA induced apoptosis through promoting ROS generation and mitochondrial depolarization when cells were subjected to oxygen deficiency. Conversely, HIF-1αB was primarily responsible for mitophagy induction, prompting ATP production to mitigate apoptosis. HIF-1αA did not induce mitophagy in the mitochondria and lysosomes co-localization assay but it was involved in the regulation of different mitophagy pathways. Over-expression of HIF-1αA increased the expression of bnip3, fundc1, Beclin1, and foxo3, suggesting it has a dual role in mitochondrial autophagy and cell death. Each duplicated copy also experienced functional divergence and target shifting in the regulation of complexes in the mitochondrial electron transport chain (ETC). Our findings shed light on the post-subfunctionalization function of HIF-1αA and HIF-1αB in zebrafish to fine-tune regulation of mitophagy and apoptosis following hypoxia exposure.

Anticancer Mechanism of Flavonoids on High-Grade Adult-Type Diffuse Gliomas

High-grade adult-type diffuse gliomas are the most common and deadliest malignant adult tumors of the central nervous system. Despite the advancements in the multimodality treatment of high-grade adult-type diffuse gliomas, the five-year survival rates still remain poor. The biggest challenge in treating high-grade adult-type diffuse gliomas is the intra-tumor heterogeneity feature of the glioma tumors. Introducing dietary flavonoids to the current high-grade adult-type diffuse glioma treatment strategies is crucial to overcome this challenge, as flavonoids can target several molecular targets. This review discusses the anticancer mechanism of flavonoids (quercetin, rutin, chrysin, apigenin, naringenin, silibinin, EGCG, genistein, biochanin A and C3G) through targeting molecules associated with high-grade adult-type diffuse glioma cell proliferation, apoptosis, oxidative stress, cell cycle arrest, migration, invasion, autophagy and DNA repair. In addition, the common molecules targeted by the flavonoids such as Bax, Bcl-2, MMP-2, MMP-9, caspase-8, caspase-3, p53, p38, Erk, JNK, p38, beclin-1 and LC3B were also discussed. Moreover, the clinical relevance of flavonoid molecular targets in high-grade adult-type diffuse gliomas is discussed with comparison to small molecules inhibitors: ralimetinib, AMG232, marimastat, hydroxychloroquine and chloroquine. Despite the positive pre-clinical results, further investigations in clinical studies are warranted to substantiate the efficacy and safety of the use of flavonoids on high-grade adult-type diffuse glioma patients.

Refining the Role of Pyruvate Dehydrogenase Kinases in Glioblastoma Development

Glioblastoma (GB) are the most frequent brain cancers. Aggressive growth and limited treatment options induce a median survival of 12–15 months. In addition to highly proliferative and invasive properties, GB cells show cancer-associated metabolic characteristics such as increased aerobic glycolysis. Pyruvate dehydrogenase (PDH) is a key enzyme complex at the crossroads between lactic fermentation and oxidative pathways, finely regulated by PDH kinases (PDHKs). PDHKs are often overexpressed in cancer cells to facilitate high glycolytic flux. We hypothesized that targeting PDHKs, by disturbing cancer metabolic homeostasis, would alter GB progression and render cells vulnerable to additional cancer treatment. Using patient databases, distinct expression patterns of PDHK1 and PDHK2 in GB tissues were obvious. To disturb protumoral glycolysis, we modulated PDH activity through the genetic or pharmacological inhibition of PDHK in patient-derived stem-like spheroids. Striking effects of PDHKs inhibition using dichloroacetate were observed in vitro on cell morphology and metabolism, resulting in increased intracellular ROS levels and decreased proliferation and invasion. In vivo findings confirmed a reduction in tumor size and better survival of mice implanted with PDHK1 and PDHK2 knockout cells. Adding a radiotherapeutic protocol further resulted in a reduction in tumor size and improved mouse survival in our model.

Dual-specificity Tyrosine Phosphorylation-regulated Kinase Inhibitor ID-8 Promotes Human Somatic Cell Reprogramming by Activating PDK4 Expression

BACKGROUND

Human induced pluripotent stem cells (hiPSCs) hold great potentials in disease modeling, drug screening and cell therapy. However, efficiency and costs of hiPSCs preparation still need to be improved.

METHODS

We screened the compounds that target signaling pathways, epigenetic modifications or metabolic-process regulation to replace the growth factors. After small molecule treatment, TRA-1-60, which is a cell surface antigen expressed by human embryonic stem cells (hESCs), staining was performed to quantify the efficiency of somatic cell reprogramming. Next, small molecule cocktail-induced ESCs or iPSCs were examined with pluripotent markers expression. Finally, Genome-wide gene expression profile was analyzed by RNA-seq to illustrate the mechanism of human somatic cell reprogramming.

RESULT

Here, we found that a dual-specificity tyrosine phosphorylation-regulated kinase (DYRK) inhibitor ID-8 robustly enhanced human somatic cell reprogramming by upregulation of pyruvate dehydrogenase kinase 4 (PDK4) and activation of glycolysis. Furthermore, we identified a novel growth-factor-free hiPSC generation system using small molecules ID-8 (I) and TGFβ signal pathway agonist Kartogenin (K). Importantly, we developed IK medium combined with low-dose bFGF to support the long-term expansion of human pluripotent stem cells. IK-iPSCs showed pluripotency and normal karyotype.

CONCLUSIONS

Our studies may provide a novel growth-factor-free culture system to facilitate the generation of hiPSCs for multiple applications in regenerative medicine. In Brief Xu et at. found that a dual-specificity tyrosine phosphorylation-regulated kinase (DYRK) inhibitor ID-8 robustly enhanced human somatic cell reprogramming by upregulation of PDK4 and activation of glycolysis. Furthermore, we established a novel growth-factor-free hiPSC generation system using small molecules ID-8/Kartogenin (IK). IK medium combined with Low-dose bFGF (IKB medium) supported the long-term expansion of human pluripotent stem cells. Highlights ID-8 Enhanced Reprogramming of Human Fibroblasts and Astrocytes Establishment of the Growth-factor-free Reprogramming System Using Small Molecule Compounds IK IKB Medium Maintained the Long-term Expansion of Human Pluripotent Stem Cells ID-8 Promoted Human Somatic Cell Reprogramming by Activating PDK4 Expression.

The Signaling Pathways Controlling the Efficacy of Glioblastoma Therapy

The resistance of glioblastoma to existing therapies puts limits on quality-of-life improvements and patient survival with a glioblastoma diagnosis. The development of new effective glioblastoma therapies is based on knowledge about the mechanisms governing tumor resistance to therapeutic agents. Virotherapy is one of the most actively developing approaches to the treatment of malignant neoplasms: glioblastoma in particular. Previously, we demonstrated that the recombinant vaccinia virus VV-GMCSF-Lact exhibits in vitro cytotoxic activity and in vivo antitumor efficacy against human glioblastoma. However, the studied glioblastoma cell cultures had different sensitivities to the oncotoxic effect of the virus. In this study, we investigated cancer stem cell (CSC) surface markers in glioblastoma cells with different sensitivities to VV-GMCSFLact using flow cytometry and we assessed the levels of proteins affecting viral entry into cells and virus infection efficiency by western blotting. We showed that cell cultures more sensitive to VV-GMCSF-Lact are characterized by a greater number of cells with CSC markers and a lower level of activated Akt kinase. Akt probably inhibits lactaptin-induced apoptosis in virus-resistant cells. Hence, we suggest that the sensitivity of glioblastoma cells to the oncotoxic effect of VV-GMCSF-Lact is determined by the nature and extent of the disturbances in cell death regulation in various cultures. Further investigation of the factors affecting glioblastoma resistance to virotherapy will test this hypothesis and identify targets for antitumor therapy, combined with VV-GMCSF-Lact.

Precision targeting tumor cells using cancer-specific InDel mutations with CRISPR-Cas9

The targeted killing of cancer cells without affecting surrounding normal cells is the most desirable approach for cancer therapy; however, it cannot be easily achieved, owing to the shared properties of normal and cancer cells. Using CRISPR-Cas9 targeting multiple cancer-specific mutations, we developed an innovative approach called cancer-specific insertions and deletions attacker that can induce targeted cancer cell death by simultaneous and multiple DNA double-strand breaks. As demonstrated in cell lines, cancer patient–driven cells and xenografts, the concept proposed in this study may become a potential approach for personalized cancer treatments.

An ideal cancer therapeutic strategy involves the selective killing of cancer cells without affecting the surrounding normal cells. However, researchers have failed to develop such methods for achieving selective cancer cell death because of shared features between cancerous and normal cells. In this study, we have developed a therapeutic strategy called the cancer-specific insertions–deletions (InDels) attacker (CINDELA) to selectively induce cancer cell death using the CRISPR-Cas system. CINDELA utilizes a previously unexplored idea of introducing CRISPR-mediated DNA double-strand breaks (DSBs) in a cancer-specific fashion to facilitate specific cell death. In particular, CINDELA targets multiple InDels with CRISPR-Cas9 to produce many DNA DSBs that result in cancer-specific cell death. As a proof of concept, we demonstrate here that CINDELA selectively kills human cancer cell lines, xenograft human tumors in mice, patient-derived glioblastoma, and lung patient-driven xenograft tumors without affecting healthy human cells or altering mouse growth.

LncRNA POT1-AS1 accelerates the progression of gastric cancer by serving as a competing endogenous RNA of microRNA-497-5p to increase PDK3 expression

BACKGROUND

Gastric cancer (GC) is the most common malignant tumor of the digestive system. Although progress has been reported in terms of treatment, it is still the second leading cause of cancer-related death. Long non-coding RNAs have been shown to play a key role in human cancers in recent investigations. However, the role of POT1-AS1 in GC is still unclear.

METHODS

The relative POT1-AS1 level in GC tissues and paracancerous tissues was detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The biological function of POT1-AS1 was studied by CCK8 and Transwell assays in vitro experiments. Moreover, the downstream target genes of POT1-AS1 were predicted by bioinformatics.

RESULTS

In this study, high POT1-AS1 expression in GC cells was confirmed, and its elevated expression was linked to patients' negative clinicopathological characteristics, as well as shorter disease-free survival (DFS) and overall survival (OS). POT1-AS1 was shown to serve as a competing endogenous RNA (ceRNA) by sponging miR-497-5p to increase PDK3 expression. The impact of POT1-AS1 silencing on GC malignant phenotypes could be reversed by suppressing miR-497-5p or restoring PDK3, according to rescue experiments.

CONCLUSIONS

In brief, POT1-AS1 acted as an oncogenic lncRNA in GC, facilitating GC development by affecting the miR-497-5p/PDK3 axis, implying that the POT1-AS1/miR-497-5p/PDK3 axis is a useful target in anticancer therapy.

Specific cyprinid HIF isoforms contribute to cellular mitochondrial regulation

Hypoxia-inducible factor 1 (HIF-1) functions as a master regulator of the cellular response to hypoxic stress. Two HIF-1α paralogs, HIF-1αA and HIF-1αB, were generated in euteleosts by the specific, third round of genome duplication, but one paralog was later lost in most families with the exception of cyprinid fish. How these duplicates function in mitochondrial regulation and whether their preservation contributes to the hypoxia tolerance demonstrated by cyprinid fish in freshwater environments is not clear. Here we demonstrated the divergent function of these two zebrafish Hif-1a paralogs through cellular approaches. The results showed that Hif-1aa played a role in tricarboxylic acid cycle by increasing the expression of Citrate synthase and the activity of mitochondrial complex II, and it also enhanced mitochondrial membrane potential and ROS production by reducing free Ca²⁺ in the cytosol. Hif-1ab promoted intracellular ATP content by up-regulating the activity of mitochondrial complexes I, III and IV and the expression of related genes. Furthermore, both the two zebrafish Hif-1a paralogs promoted mitochondrial mass and the expression level of mtDNA, contributing to mitochondrial biogenesis. Our study reveals the divergent functions of Hif-1aa and Hif-1ab in cellular mitochondrial regulation.

Peptidylarginine Deiminase Isozyme-Specific PAD2, PAD3 and PAD4 Inhibitors Differentially Modulate Extracellular Vesicle Signatures and Cell Invasion in Two Glioblastoma Multiforme Cell Lines

Glioblastoma multiforme (GBM) is an aggressive adult brain tumour with poor prognosis. Roles for peptidylarginine deiminases (PADs) in GBM have recently been highlighted. Here, two GBM cell lines were treated with PAD2, PAD3 and PAD4 isozyme-specific inhibitors. Effects were assessed on extracellular vesicle (EV) signatures, including EV-microRNA cargo (miR21, miR126 and miR210), and on changes in cellular protein expression relevant for mitochondrial housekeeping (prohibitin (PHB)) and cancer progression (stromal interaction molecule 1 (STIM-1) and moesin), as well as assessing cell invasion. Overall, GBM cell-line specific differences for the three PAD isozyme-specific inhibitors were observed on modulation of EV-signatures, PHB, STIM-1 and moesin protein levels, as well as on cell invasion. The PAD3 inhibitor was most effective in modulating EVs to anti-oncogenic signatures (reduced miR21 and miR210, and elevated miR126), to reduce cell invasion and to modulate protein expression of pro-GBM proteins in LN229 cells, while the PAD2 and PAD4 inhibitors were more effective in LN18 cells. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways for deiminated proteins relating to cancer, metabolism and inflammation differed between the two GBM cell lines. Our findings highlight roles for the different PAD isozymes in the heterogeneity of GBM tumours and the potential for tailored PAD-isozyme specific treatment.

Overexpression of PDK2 and PDK3 reflects poor prognosis in acute myeloid leukemia

Acute myeloid leukemia (AML) is a hematological malignancy characterized by the proliferation of immature myeloid cells, with impaired differentiation and maturation. Pyruvate dehydrogenase kinase (PDK) is a pyruvate dehydrogenase complex (PDC) phosphatase inhibitor that enhances cell glycolysis and facilitates tumor cell proliferation. Inhibition of its activity can induce apoptosis of tumor cells. Currently, little is known about the role of PDKs in AML. Therefore, we screened The Cancer Genome Atlas (TCGA) database for de novo AML patients with complete clinical information and PDK family expression data, and 84 patients were included for the study. These patients did not undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT). Univariate analysis showed that high expression of PDK2 was associated with shorter EFS (P = 0.047), and high expression of PDK3 was associated with shorter OS (P = 0.026). In multivariate analysis, high expression of PDK3 was an independent risk factor for EFS and OS (P < 0.05). In another TCGA cohort of AML patients who underwent allo-HSCT (n = 71), PDK expression was not associated with OS (all P > 0.05). Our results indicated that high expressions of PDK2 and PDK3, especially the latter, were poor prognostic factors of AML, and the effect could be overcome by allo-HSCT.

miR-497-5p inhibits gastric cancer cell proliferation and growth through targeting PDK3

MicroRNA plays an important role in gastric cancer (GC) development, while the function of miR-497-5p in this disease remains unknown. In the present study, we demonstrated miR-497-5p as a tumor suppressive microRNA in GC. miR-497-5p was down-regulated in GC tissues and its expression was associated with the disease stage. Inhibition of miR-497-5p promoted GC cell proliferation and growth. By contrast, miR-497-5p ectopic expression suppressed the proliferation and growth of GC cells. In addition, miR-497-5p inhibited DNA synthesis and enhanced apoptosis in GC cells. The cell cycle progression was suppressed by miR-497-5p. Mechanistically, miR-497-5p directly targeted and suppressed the expression of pyruvate dehydrogenase kinase 3 (PDK3), which is highly expressed in GC tissues. Over-expression of PDK3 promoted the proliferation of GC cells. Our study revealed that miR-497-5p inhibited GC cell proliferation and growth via targeting PDK3.

SIRT3 elicited an anti-Warburg effect through HIF1α/PDK1/PDHA1 to inhibit cholangiocarcinoma tumorigenesis

Cholangiocarcinoma (CCA) is an extremely invasive malignancy with late diagnosis and unfavorable prognosis. Surgery and chemotherapy are still not effective in improving outcomes in CCA patients. It is crucial to explore a novel therapeutic target for treating CCA. An NAD‐dependent deacetylase also known as Sirtuin‐3 (SIRT3) has been shown to regulate cellular metabolism in various cancers dynamically. However, the biological function of SIRT3 in CCA remains unclear. In this study, bioinformatics analyses were performed to identify the differentially expressed genes and pathways enriched. CCA samples were collected for immunohistochemical analysis. Three human CCA cell lines (HuCCT1, RBE, and HCCC9810) were used to explore the molecular mechanism of SIRT3 regulation of metabolic reprogramming and malignant behavior in CCA. A CCA xenograft model was then established for further validation in vivo. The data showed that SIRT3 expression was decreased and glycolysis was enhanced in CCA. Similar metabolic reprogramming was also observed in SIRT3 knockout mice. Furthermore, we demonstrated that SIRT3 could play an anti‐Warburg effect by inhibiting the hypoxia‐inducible factor‐1α (HIF1α)/pyruvate dehydrogenase kinase 1 (PDK1)/pyruvate dehydrogenase (PDHA1) pathway in CCA cells. CCA cell proliferation and apoptosis were regulated by SIRT3‐mediated metabolic reprogramming. These findings were further confirmed in CCA clinical samples and the xenograft model. Collectively, this study suggests that in the inhibition of CCA progression, SIRT3 acts through an anti‐Warburg effect on the downstream pathway HIF1α/PDK1/PDHA1.