ASK1/JNK-mediated TAp63 activation controls the cell survival signal of baicalein-treated EBV-transformed B cells

Baicalin and baicalein in modulating tumor microenvironment for cancer treatment: A comprehensive review with future perspectives

Cancer is a leading cause of death worldwide. The burden of cancer incidence and mortality is increasing rapidly. New approaches to cancer prevention and treatment are urgently needed. Natural products are reliable and powerful sources for anticancer drug discovery. Baicalin and baicalein, two major flavones isolated from Scutellaria baicalensis Georgi, a multi-purpose traditional medicinal plant in China, exhibit anticancer activities against multiple cancers. Of note, these phytochemicals exhibit extremely low toxicity to normal cells. Besides their cytotoxic and cytostatic activities toward diverse tumor cells, recent studies demonstrated that baicalin and baicalein modulate a variety of tumor stromal cells and extracellular matrix (ECM) in the tumor microenvironment (TME), which is essential for tumorigenesis, cancer progression and metastasis. In this review, we summarize the therapeutic potential and the mechanism of action of baicalin and baicalein in the regulation of tumor microenvironmental immune cells, endothelial cells, fibroblasts, and ECM that reshape the TME and cancer signaling, leading to inhibition of tumor angiogenesis, progression, and metastasis. In addition, we discuss the biotransformation pathways of baicalin and baicalein, related therapeutic challenges and the future research directions to improve their bioavailability and clinical anticancer applications. Recent advances of baicalin and baicalein warrant their continued study as important natural ways for cancer interception and therapy.

Molecular Mechanisms of Flavonoids against Tumor Gamma-Herpesviruses and Their Correlated Cancers-A Focus on EBV and KSHV Life Cycles and Carcinogenesis

Epstein-Barr virus (EBV) and Kaposi sarcoma-associated herpesvirus (KSHV) are cancer-causing viruses that belong to human gamma-herpesviruses. They are DNA viruses known to establish lifelong infections in humans, with the ability to develop various types of cancer. Drug resistance remains the main barrier to achieving effective therapies for viral infections and cancer. Thus, new medications with dual antiviral and anticancer actions are highly needed. Flavonoids are secondary metabolites biosynthesized by plants with diverse therapeutic effects on human health. In this review, we feature the potential role of flavonoids (flavones, protoflavones, isoflavones, flavanones, flavonols, dihydroflavonols, catechins, chalcones, anthocyanins, and other flavonoid-type compounds) in controlling gamma-herpesvirus-associated cancers by blocking EBV and KSHV infections and inhibiting the formation and growth of the correlated tumors, such as nasopharyngeal carcinoma, Burkitt's lymphoma, gastric cancer, extranodal NK/T-cell lymphoma, squamous cell carcinoma, Kaposi sarcoma, and primary effusion lymphoma. The underlying mechanisms via targeting EBV and KSHV life cycles and carcinogenesis are highlighted. Moreover, the effective concentrations or doses are emphasized.

Exercise inhibits JNK pathway activation and lipotoxicity via macrophage migration inhibitory factor in nonalcoholic fatty liver disease

The macrophage migration inhibitory factor (MIF) expressed in hepatocytes can limit steatosis during obesity. Lipotoxicity in nonalcoholic fatty liver disease is mediated in part by the activation of the stress kinase JNK, but whether MIF modulates JNK in lipotoxicity is unknown. In this study, we investigated the role of MIF in regulating JNK activation and high-fat fostered liver lipotoxicity during simultaneous exercise treatment. Fifteen mice were equally divided into three groups: normal diet, high-fat diet, and high-fat and exercise groups. High-fat feeding for extended periods elicited evident hyperlipemia, liver steatosis, and cell apoptosis in mice, with inhibited MIF and activated downstream MAPK kinase 4 phosphorylation and JNK. These effects were then reversed following prescribed swimming exercise, indicating that the advent of exercise could prevent liver lipotoxicity induced by lipid overload and might correlate to the action of modulating MIF and its downstream JNK pathway. Similar detrimental effects of lipotoxicity were observed in in vitro HepG2 cells palmitic acid treatment. Suppressed JNK reduced the hepatocyte lipotoxicity by regulating the BCL family, and the excess JNK activation could also be attenuated through MIF supplementation or exacerbated by MIF siRNA administration. The results found suggest that exercise reduces lipotoxicity and inhibits JNK activation by modulating endogenous hepatic MIF in NAFLD. These findings have clinical implications for the prevention and intervention of patients with immoderate diet evoked NAFLD.

Puerarin suppresses the hepatic gluconeogenesis via activation of PI3K/Akt signaling pathway in diabetic rats and HepG2 cells

Pueraria, a Chinese herbal medicine, plays an important role in many classic prescriptions for the treatment of diabetes. Puerarin is the main component of pueraria. The current in vivo and in vitro research mainly focus on exploring the potential mechanism of puerarin in inhibiting hepatic gluconeogenesis. The type 2 diabetic rats were established by a combination of small dosage of streptozotocin (STZ) injection with high-fat diet. After the administration of puerarin 4 weeks, the parameters of the glucose and lipid metabolism were determined. HepG2 cells were treated by palmitic acid (PA) to induce the insulin resistance in vitro model. After the treatment of puerarin, the glucose consumption and cell viability were examined. Then, the protein expression of PI3K, Akt, pAkt, pFOXO1, FOXO1, PEPCK and G6pase in liver tissue and HepG2 cells were evaluated by western blot. RT-PCR was used to measure the content of PEPCK, G6pase mRNA in liver tissue. The results showed that puerarin administration significantly decrease the level of FBG, HbA1C and triglycerides in diabetic rats. Mechanistic research showed that puerarin activating PI3K/Akt is puerarin-mediated beneficial effects and can be reversed by inhibitor of PI3K or Akt. In conclusion, puerarin inhibits hepatic gluconeogenesis by activating PI3K/Akt signaling pathway.

Modified TLR-mediated downregulation of miR-125b-5p enhances CD248 (endosialin)-induced metastasis and drug resistance in colorectal cancer cells

CD248, also called endosialin or tumor endothelial marker-1, is markedly upregulated in almost all cancers, including colon cancers. Changes in microRNA profiles are one of the direct causes of cancer development and progression. In this study, we investigated whether a change in CD248 expression in colon cancer cells could induce drug resistance after chemotherapy, and we explored the relationship between miR-125b-5p levels and CD248 expression in Toll-like receptor (TLR)-modified chemoresistant colon cancer cells. TLR2/6 and TLR5 upregulation in drug-resistant colon cancer cells contributed to miR-125b-5p downregulation and specificity protein 1 (Sp1)-mediated CD248 upregulation via nuclear factor-kappa B (NF-κB) activation. Exposure to specific TLR2/6 or TLR5 ligands enhanced the expression of mesenchymal markers as well as the migratory activity of oxaliplatin- or 5-fluorouracil-resistant colon cancer cells. The transfection of a synthetic miR-125b-5p mimic into chemoresistant cells prevented Sp1 and CD248 activation and significantly impaired invasive activity. Furthermore, Sp1 or CD248 gene silencing as well as miR-125b-5p overexpression markedly reversed drug resistance and inhibited epithelial-mesenchymal transition in colon cancer cells. Taken together, these results suggest that changes in miR-125b-5p levels play an important role in Sp1-mediated CD248 expression and the development of drug resistance in TLR-mutated colon cancer cells.

Gliotoxin Enhances Autophagic Cell Death via the DAPK1-TAp63 Signaling Pathway in Paclitaxel-Resistant Ovarian Cancer Cells

Death-associated protein kinase 1 (DAPK1) expression induced by diverse death stimuli mediates apoptotic activity in various cancers, including ovarian cancer. In addition, mutual interaction between the tumor suppressor p53 and DAPK1 influences survival and death in several cancer cell lines. However, the exact role and connection of DAPK1 and p53 family proteins (p53, p63, and p73) in drug-resistant ovarian cancer cells have not been studied previously. In this study, we investigated whether DAPK1 induction by gliotoxin derived from marine fungus regulates the level of transcriptionally active p63 (TAp63) to promote apoptosis in an autophagy-dependent manner. Pre-exposure of paclitaxel-resistant ovarian cancer cells to gliotoxin inhibited the expression of multidrug resistant-associated proteins (MDR1 and MRP1-3), disrupted the mitochondrial membrane potential, and induced caspase-dependent apoptosis through autophagy induction after subsequent treatment with paclitaxel. Gene silencing of DAPK1 prevented TAp63-mediated downregulation of MDR1 and MRP1-3 and autophagic cell death after sequential treatment with gliotoxin and then paclitaxel. However, pretreatment with 3-methyladenine (3-MA), an autophagy inhibitor, had no effect on the levels of DAPK1 and TAp63 or on the inhibition of MDR1 and MRP1-3. These results suggest that DAPK1-mediated TAp63 upregulation is one of the critical pathways that induce apoptosis in chemoresistant cancer cells.

Baicalein inhibits growth of Epstein-Barr virus-positive nasopharyngeal carcinoma by repressing the activity of EBNA1 Q-promoter

Epstein-Barr virus (EBV) can establish a life-long latent infection in the host and is associated with various human malignancies, including nasopharyngeal carcinoma (NPC), the most common cancer originated from nasopharynx. EBV nuclear antigen 1 (EBNA1) is the only viral protein absolutely demanded for segregation, replication, transcription and maintenance of EBV viral genome in host cells. Baicalein, a bioactive flavonoid compound purified from the root of Scutellariae baicaleinsis, displays anti-inflammatory, immunosuppressive, and anti-tumor properties. In this study, the therapeutic effects and functional mechanism of baicalein on EBV-positive human NPC were determined. Cell Counting Kit-8 assays and cell formation colony were performed to investigate that baicalein can suppress proliferation of EBV-infected human NPC cells. Flow cytometric and hoechst 33258 staining results indicated that baicalein induced cell cycle arrest and apoptosis. Western blotting results demonstrated that baicalein down-regulates EBNA1 expression but not reduces the stability and half-life of EBNA1 in EBV-infected NPC cells. Additionally, the mRNA level of EBNA1 was examined by real time-PCR, the activity of EBNA1 Q promoter (Qp) was determined by dual luciferase reporter assay. Considering that transcription factor specificity protein 1 (Sp1) can maintain EBNA1 Qp active. Further analyses also elucidated that baicalein inhibits the expression of Sp1 while knock-down Sp1 by specific shRNAs decreases the expression and transcription levels of EBNA1. Therefore, the results suggested that baicalein may decrease EBNA1 expression level in EBV-positive NPC cells via inhibiting the activity of EBNA1 Q-promoter while over-expression of EBNA1 attenuate the inhibitory effect of baicalein. Finally, it was found that baicalein may strongly reduce growth of tumor in the mouse xenograft model of EBV-positive NPC. These results indicated that baicalein inhibits growth of EBV-positive NPC by repressing the activity of EBNA1 Q-promoter. Baicalein may be used as a therapeutic agent to treat EBV-positive NPC.

TAp63 is correlated with chronic inflammation in patients with newly diagnosed type 2 diabetes mellitus

AIMS

To investigate TAp63 expression in patients with type 2 diabetes mellitus (T2DM) and the potential correlations between TAp63 and proinflammatory cytokines production and other clinical parameters.

METHODS

Peripheral blood mononuclear cells (PBMCs) and plasma were collected from 72 T2DM (cases) and 72 healthy subjects (controls). Fasting blood glucose (FBG), fasting insulin (FIN) and a blood lipid profile were measured. The homeostasis model assessment (HOMA) was used to estimate insulin resistance (IR). Plasma tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 were determined. PBMCs isolated from healthy subjects were cultured with or without 33.3 mmol/l glucose or 0.5 mmol/l palmitic acid (PA) for 6 h, 24 h, 48 h, and 72 h. The expression of TAp63 at mRNA and protein levels in PBMCs was analyzed using real-time qRT-PCR and western blots, respectively.

RESULTS

TAp63 expression was significantly lower in T2DM patients compared with that of the controls. In addition, TAp63 expression showed a negative correlation with FBG, FIN, HbA1c, HOMA-IR, FFAs, TNF-α, and IL-6 levels. Treatment with 33.3 mmol/l glucose or 0.5 mmol/l PA increased TAp63 expression in the cultured PBMCs.

CONCLUSIONS

TAp63 level may be correlated with chronic inflammatory state and perturbed glucose and lipid metabolism in T2DM.

Negative feedback between TAp63 and Mir-133b mediates colorectal cancer suppression

Background

TAp63 is known as the most potent transcription activator and tumor suppressor. microRNAs (miRNAs) are increasingly recognized as essential components of the p63 pathway, mediating downstream post-transcriptional gene repression. The aim of present study was to investigate a negative feedback loop between TAp63 and miR-133b.

Results

Overexpression of TAp63 inhibited HCT-116 cell proliferation, apoptosis and invasion via miR-133b. Accordingly, miR-133b inhibited TAp63 expression through RhoA and its downstream pathways. Moreover, we demonstrated that TAp63/miR-133b could inhibit colorectal cancer proliferation and metastasis in vivo and vitro.

Materials and Methods

We evaluated the correlation between TAp63 and miR-133b in HCT-116 cells and investigated the roles of the TAp63/miR-133b feedback loop in cell proliferation, apoptosis and metastasis via MTT, flow cytometry, Transwell, and nude mouse xenograft experiments. The expression of TAp63, miR-133b, RhoA, α-tubulin and Akt was assessed via qRT-PCR, western blot and immunofluorescence analyses. miR-133b target genes were identified through luciferase reporter assays.

Conclusions

miR-133b plays an important role in the anti-tumor effects of TAp63 in colorectal cancer. miR-133b may represent a tiemolecule between TAp63 and RhoA, forming a TAp63/miR-133b/RhoA negative feedback loop, which could significantly inhibit proliferation, apoptosis and metastasis.

Macrophage migration inhibitory factor: a potential driver and biomarker for head and neck squamous cell carcinoma

Macrophage migration inhibitory factor (MIF), a pleiotropic proinflammatory cytokine, has been showed to be associated with the immunopathogenesis of many diseases. Recent study demonstrated that MIF promoted tumorigenesis and tumor progression and played a critical role in various kinds of human cancer including head and neck squamous cell carcinoma(HNSCC). Hence, in this paper we retrospected the relationship between MIF and angiogenesis, epithelial-mesenchymal transition (EMT), inflammation, immune response, hypoxia microenvironment, and discussed whether it is a promising biomarker for diagnosis and supervisor of HNSCC.

GSK-3β-mediated fatty acid synthesis enhances epithelial to mesenchymal transition of TLR4-activated colorectal cancer cells through regulation of TAp63

Glycogen synthase kinase-3β (GSK-3β) in cancer cells is a critical regulatory component of both cellular metabolism and epithelial-mesenchymal transition (EMT) processes via regulation of the β-catenin/E-cadherin and phosphoinositide 3-kinase (PI3K)/AKT signaling pathway. Lipogenesis of cancer cells also plays a critical role in survival and metastasis. We investigated the role of GSK-3β-mediated intracellular fatty acid synthesis to control EMT in TLR4-activated colorectal cancer cells and the underlying regulatory mechanism. Engagement of TLR4 with lipopolysaccharide (LPS) in colon cancer cells promoted the induction of phosphorylated GSK-3β and related lipogenic enzymes as well as the expression of CD74, CD44 and macrophage inhibitory factor (MIF), but decreased expression of transcriptionally active p63 (TAp63). In addition, targeted inhibition of GSK-3β using SB216763 was accompanied by decreased intracellular fatty acid synthesis and blockage of CD74 and CD44 expression, whereas it reversed the level of TAp63. Although TAp63 overexpression had no effect on the expression of CD74 and CD44 in LPS-treated colon cancer cells, GSK-3β-dependent fatty acid synthesis and invasive activity were significantly suppressed. Notably, inhibition of CD44 or CD74 by siRNA not only attenuated de novo lipogenesis and migratory activity but also restored the expression of TAp63 in LPS-activated colon cancer cells. These results suggest that TAp63-mediated GSK-3β activation induced by TLR4 stimulation triggers migration and invasion of colon cancer cells through the regulation of lipid synthesis and GSK-3β-mediated CD74/CD44 expression could be a target to control fatty acid-related EMT process through the modulation of TAp63 expression.