T0070907, a PPAR γ inhibitor, induced G2/M arrest enhances the effect of radiation in human cervical cancer cells through mitotic catastrophe

Nuclear receptors as novel regulators that modulate cancer radiosensitivity and normal tissue radiotoxicity

Nuclear receptors (NRs) are a superfamily of transcription factors that are involved in various pathophysiological processes. The human genome contains 48 types of nuclear receptors, including steroid hormone receptors (e.g., estrogen receptor [ER] and vitamin D receptor [VDR]), nonsteroid hormone receptors (e.g. peroxisome proliferator-activated receptor [PPAR] and retinoic acid receptor [RAR]), and orphan nuclear receptors (e.g. neuron-derived clone 77 [Nur77] and testicular nuclear receptor 4 [TR4]) and certain nuclear receptors are specifically overexpressed in tumor cells or surrounding normal tissues. Radiotherapy is one of the main methods of tumor treatment, but radioresistance in tumors and radiotoxicity to normal tissues strongly affect radiotherapy efficacy. Accumulating evidence has indicated the critical role of nuclear receptor modulators (including agonists and antagonists) as promising radiosensitizers in radiotherapy through various mechanisms. In addition, several nuclear receptors and their agonists alleviate normal tissue toxicity during radiotherapy. Thus, nuclear receptors serve as novel targets for tumor radiosensitization and for protecting of normal tissues from radiation damage. This review summarizes the research progress of nuclear receptors and highlights a promising synergistic strategy in radiotherapy.

PPAR-γ in Melanoma and Immune Cells: Insights into Disease Pathogenesis and Therapeutic Implications

Changes in skin pigmentation, like hyperpigmentation or moles, can affect appearance and social life. Unlike locally containable moles, malignant melanomas are aggressive and can spread rapidly, disproportionately affecting younger individuals with a high potential for metastasis. Research has shown that the peroxisome proliferator-activated receptor gamma (PPAR-γ) and its ligands exhibit protective effects against melanoma. As a transcription factor, PPAR-γ is crucial in functions like fatty acid storage and glucose metabolism. Activation of PPAR-γ promotes lipid uptake and enhances sensitivity to insulin. In many cases, it also inhibits the growth of cancer cell lines, like breast, gastric, lung, and prostate cancer. In melanoma, PPAR-γ regulates cell proliferation, differentiation, apoptosis, and survival. During tumorigenesis, it controls metabolic changes and the immunogenicity of stromal cells. PPAR-γ agonists can target hypoxia-induced angiogenesis in tumor therapy, but their effects on tumors can be suppressive or promotional, depending on the tumor environment. Published data show that PPAR-γ-targeting agents can be effective in specific groups of patients, but further studies are needed to understand lesser-known biological effects of PPAR-γ and address the existing safety concerns. This review provides a summary of the current understanding of PPAR-γ and its involvement in melanoma.

High-Throughput Repurposing Screen Reveals Compounds with Activity against Toxoplasma gondii Bradyzoites

Toxoplasma gondii causes widespread chronic infections that are not cured by current treatments due to the inability to affect semidormant bradyzoite stages within tissue cysts. To identify compounds to eliminate chronic infection, we developed an HTS using a recently characterized strain of T. gondii that undergoes efficient conversion to bradyzoites in vitro. Stage-specific expression of luciferase was used to selectively monitor the growth inhibition of bradyzoites by the Library of Pharmacological Active Compounds, consisting of 1280 drug-like compounds. We identified 44 compounds with >50% inhibitory effects against bradyzoites, including new highly potent compounds, several of which have precedent for antimicrobial activity. Subsequent characterization of the compound sanguinarine sulfate revealed potent and rapid killing against in vitro-produced bradyzoites and bradyzoites harvested from chronically infected mice, including potent activity against intact cysts. These findings provide a platform for expanded screening and identify promising compounds for further preclinical development against T. gondii bradyzoites that are responsible for chronic infection.

Elucidating the role of PPARG inhibition in enhancing MERS virus immune response: A network pharmacology and computational drug discovery

BACKGROUND

Middle East Respiratory Syndrome (MERS) has become a severe zoonotic disease, posing significant public health concerns due to the lack of specific medications. This urgently demands the development of novel therapeutic molecules. Understanding MERS's genetic underpinnings and potential therapeutic targets is crucial for developing effective treatments.

METHODS

Two gene expression datasets (GSE81909 and GSE100504) were analyzed to identify differentially expressed genes (DEGs) using GEO2R. Furthermore, gene ontology (GO), pathway enrichment analysis, and protein-protein interaction (PPI) network were performed to understand the gene's functions. A possible drug target was identified, and an FDA-approved drug library was screened against the selected target using molecular docking and validated the findings through molecular dynamics simulation, principal component analysis, free energy landscape, and MM/GBSA calculations.

RESULTS

The study on GSE81909 and GSE100504 datasets with icMERS and MOCK samples at 24 and 48 h revealed an upregulation in 73 and 267 DEGs, respectively. In the network pharmacology, STAT1, MX1, DDX58, EIF2AK2, ISG15, IFIT1, IFIH1, OAS1, IRF9, and OASL were identified as the top 10 hub genes. STAT1 was identified as the most connected hub gene among these top 10 hub genes, which plays a crucial role in the immune response to the MERS virus. Further study on STAT1 showed that PPARG helps reduce STAT1, which could modulate the immune response. Therefore, by inhibiting PPARG, the immunological response can be successfully enhanced. The known inhibitor of PPARG, 570 (Farglitazar), was used as a control. Further, screening using Tanimoto and K-mean clustering was performed, from which three compounds were identified: 2267, 3478, and 40326. Compound 3478 showed characteristics similar to the control, indicating robust binding to PPARG. 3478 showed the highest negative binding free energy with -41.20 kcal/mol, indicating strong binding with PPARG.

CONCLUSIONS

These findings suggest that 3478 promises to be a potential inhibitor of PPARG, and further experimental investigations can explore its potential as a MERS inhibitor.

High Throughput Repurposing Screen Reveals Compounds with Activity Against Toxoplasma gondii Bradyzoites

Toxoplasma gondii causes widespread chronic infections that are not cured by current treatments due to inability to affect semi-dormant bradyzoite stages within tissue cysts. To identify compounds to eliminate chronic infection, we developed a HTS using a recently characterized strain of T. gondii that undergoes efficient conversion to bradyzoites in intro. Stage-specific expression of luciferase was used to selectively monitor growth inhibition of bradyzoites by the Library of Pharmacological Active Compounds, consisting of 1,280 drug-like compounds. We identified 44 compounds with >50% inhibitory effects against bradyzoites, including new highly potent compounds, several of which have precedent for antimicrobial activity. Subsequent characterization of the compound Sanguinarine sulfate revealed potent and rapid killing against in vitro produced bradyzoites and bradyzoites harvested from chronically infected mice. These findings provide a platform for expanded screening and identify promising compounds for further preclinical development against T. gondii bradyzoites responsible for chronic infection.

PPARG-mediated autophagy activation alleviates inflammation in rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis (RA) is a systemic inflammatory autoimmune disease characterized by joint inflammation and bone damage, that not only restricts patient activity but also tends to be accompanied by a series of complications, seriously affecting patient prognosis. Peroxisome proliferator-activated receptor gamma (PPARG), a receptor that controls cellular metabolism, regulates the function of immune cells and stromal cells. Previous studies have shown that PPARG is closely related to the regulation of inflammation. However, the role of PPARG in regulating the pathological processes of RA is poorly understood.

MATERIALS AND METHODS

PPARG expression was examined in the synovial tissues and peripheral blood mononuclear cells (PBMCs) from RA patients and the paw of collagen-induced arthritis (CIA) model rats. Molecular biology experiments were designed to examine the effect of PPARG and cannabidiol (CBD) on RAW264.7 cells and CIA rats.

RESULTS

The results reveal that PPARG accelerates reactive oxygen species (ROS) clearance by promoting autophagy, thereby inhibiting ROS-mediated macrophage polarization and NLRP3 inflammasome activation. Notably, CBD may be a promising candidate for understanding the mechanism by which PPARG regulates autophagy-mediated inflammation.

CONCLUSIONS

Taken together, these findings indicate that PPARG may have a role for distinguishing between RA patients and healthy control, and for distinguishing RA activity; moreover, PPARG could be a novel pharmacological target for alleviating RA through the mediation of autophagy. CBD can act as a PPARG agonist that alleviates the inflammatory progression of RA.

Roles of PPAR activation in cancer therapeutic resistance: Implications for combination therapy and drug development

Therapeutic resistance is a major obstacle to successful treatment or effective containment of cancer. Peroxisome proliferator-activated receptors (PPARs) play an essential role in regulating energy homeostasis and determining cell fate. Despite of the pleiotropic roles of PPARs in cancer, numerous studies have suggested their intricate relationship with therapeutic resistance in cancer. In this review, we provided an overview of the roles of excessively activated PPARs in promoting resistance to modern anti-cancer treatments, including chemotherapy, radiotherapy, targeted therapy, and immunotherapy. The mechanisms through which activated PPARs contribute to therapeutic resistance in most cases include metabolic reprogramming, anti-oxidant defense, anti-apoptosis signaling, proliferation-promoting pathways, and induction of an immunosuppressive tumor microenvironment. In addition, we discussed the mechanisms through which activated PPARs lead to multidrug resistance in cancer, including drug efflux, epithelial-to-mesenchymal transition, and acquisition and maintenance of the cancer stem cell phenotype. Preliminary studies investigating the effect of combination therapies with PPAR antagonists have suggested the potential of these antagonists in reversing resistance and facilitating sustained cancer management. These findings will provide a valuable reference for further research on and clinical translation of PPAR-targeting treatment strategies.

Peroxisome Proliferator-Activated Receptor agonists and antagonists: an updated patent review (2020-2023)

INTRODUCTION

The search for novel compounds targeting Peroxisome Proliferator-Activated Receptors (PPARs) is currently ongoing, starting from the previous successfully identification of selective, dual or pan agonists. In last years, researchers' efforts are mainly paid to the discovery of PPARγ and δ modulators, both agonists and antagonists, selective or with a dual-multitarget profile. Some of these compounds are currently under clinical trials for the treatment of primary biliary cirrhosis, nonalcoholic fatty liver disease, hepatic, and renal diseases.

AREAS COVERED

A critical analysis of patents deposited in the range 2020-2023 was carried out. The novel compounds discovered were classified as selective PPAR modulators, dual and multitarget PPAR agonists. The use of PPAR ligands in combination with other drugs was also discussed, together with novel therapeutic indications proposed for them.

EXPERT OPINION

From the analysis of the patent literature, the current emerging landscape sees the necessity to obtain PPAR multitarget compounds, with a balanced potency on three subtypes and the ability to modulate different targets. This multitarget action holds great promise as a novel approach to complex disorders, as metabolic, inflammatory diseases, and cancer. The utility of PPAR ligands in the immunotherapy field also opens an innovative scenario, that could deserve further applications.

A glimpse of the connection between PPARγ and macrophage

Nuclear receptors are ligand-regulated transcription factors that regulate vast cellular activities and serve as an important class of drug targets. Among them, peroxisome proliferator-activated receptors (PPARs) are members of the nuclear receptor family and have been extensively studied for their roles in metabolism, differentiation, development, and cancer, among others. Recently, there has been considerable interest in understanding and defining the function of PPARs and their agonists in regulating innate and adaptive immune responses and their pharmacological potential in combating chronic inflammatory diseases. In this review, we focus on emerging evidence for the potential role of PPARγ in macrophage biology, which is the prior innate immune executive in metabolic and tissue homeostasis. We also discuss the role of PPARγ as a regulator of macrophage function in inflammatory diseases. Lastly, we discuss the possible application of PPARγ antagonists in metabolic pathologies.

The increased expression of cytokeratin 13 leads to an increase in radiosensitivity of nasopharyngeal carcinoma HNE-3 cells by upregulating ERRFI1

The main factors contributing to the unfavorable outcome in the clinical treatment of patients with nasopharyngeal carcinoma (NPC) patients are radiation resistance and recurrence. This study aimed to investigate the sensitivity and molecular foundation of cytokeratin 13 (CK13) in the radiotherapy of NPC. To achieve this, a human NPC cell line overexpressing CK13, HNE-3-CK13, was constructed. The effects of CK13 overexpression on cell viability and apoptosis under radiotherapy conditions were evaluated using the CCK-8 assay, immunofluorescence, and western blotting (WB). Next-generation sequencing was performed to identify the downstream genes and signaling pathways of CK13 that mediate radiotherapy response. The potential role of the candidate gene ERRFI1 in CK13-induced enhancement of radiosensitivity was investigated through rescue experiments using clone formation and WB. The effects of ERRFI1 on cell viability, cell apoptosis, cell cycle, and the related key genes were further evaluated using CCK-8, immunofluorescence, flow cytometry, quantitative polymerase chain reaction and WB. The results showed that CK13 overexpression in HNE-3 significantly inhibited cell survival under radiotherapy and promoted apoptosis marker γH2AX expression, leading to a significant increase of ERRFI1. Knockdown of ERRFI1 rescued the decreased cell viability and proliferation and the increased cell apoptosis that were caused by CK13 overexpression-mediated radiotherapy sensitization of NPC cells. In this process, EGFR, AKT, and GSK-3β were found involved. In the end, ERRFI1 was proven to inhibit expression levels of CDK1, CDK2, cyclin B1, and cyclin D1, resulting an increased G2/M cell ratio. Overexpression of CK13 enhances the radiosensitivity of NPC cells, which is characterized by decreased cell viability and proliferation and increased apoptosis. This regulation may affect the survival of HNE-3 cells by increasing the expression of ERRFI1 and activating the EGFR/Akt/GSK-3β signaling pathway, providing new potential therapeutic targets for the treatment of NPC.

Cytokeratin 13 promotes radiotherapy sensitivity of nasopharyngeal carcinoma by downregulating the MEK/ERK pathway

BACKGROUND

Radiation therapy is the first treatment choice for nasopharyngeal carcinoma (NPC), while radiation resistance and recurrence have become the primary factors and are associated with poor prognosis in the clinical treatment of NPC patients. The purpose of the present study was to explore the sensitivity and molecular basis of cytokeratin 13 (CK13) that regulates NPC radiotherapy.

METHODS

HNE-3 or C666-1 cell line was used for overexpression and knockdown tests. Under radiotherapy conditions, CCK-8 assay, clone formation assay, and flow cytometry analyzed the effects of CK13 overexpression on cell proliferation, apoptosis, and cell cycle, respectively. In addition, Western blotting detected CK13-mediated downregulation of cell cycle-related genes. The mouse subcutaneous tumor-bearing experiment identified the effects of CK13 overexpression on the treatment of NPC in vivo. Further, Western blotting, CCK-8 assay, and flow cytometry investigated whether the CK13-mediated cell apoptosis involves the MEK/ERK signaling pathway.

RESULTS

Overexpression of CK13 significantly inhibited the survival of HNE-3 cells under radiotherapy in vitro and in vivo, and there was a substantial decrease in cyclin-dependent kinase 4 and 6 (CDK4/6) levels promoting the cell percentage number in the G2/M phase and, subsequently, the ratio of the apoptotic cells. In contrast, the knockdown of CK13 showed the opposite partial regulatory effect. Interestingly, CK13 overexpression also showed a reduction in the survival of C666-1 cells and an increased ratio of the apoptotic cells under radiotherapy treatment. Furthermore, higher levels of CK13 downregulated the MEK/ERK signaling pathway, resulting in decreased HNE-3 cell proliferation and increased apoptosis. However, ERK activators were able to rescue the process partially.

CONCLUSIONS

Together, these results showed that CK13 promoted the radiosensitivity of NPC cells by downregulating the MEK/ERK signaling pathway. Thus, targeting CK13 provided insights into the treatment of NPC radiotherapy.

Diosmetin Targeted at Peroxisome Proliferator-Activated Receptor Gamma Alleviates Advanced Glycation End Products Induced Neuronal Injury

The present study aimed to evaluate the role of diosmetin in alleviating advanced glycation end products (AGEs)-induced Alzheimer’s disease (AD)-like pathology and to clarify the action mechanisms. Before stimulation with AGEs (200 μg/mL), SH-SY5Y cells were treated with diosmetin (10 μmol/L), increasing cell viability. The induction of AGEs on the reactive oxygen species overproduction and downregulation of antioxidant enzyme activities, including superoxide dismutase, glutathione peroxidase, and catalase, were ameliorated by diosmetin. Amyloid precursor protein upregulation, accompanied by increased production of amyloid-β, caused by AGEs, was reversed by diosmetin. In the presence of diosmetin, not only β-site amyloid precursor protein cleaving enzyme1 expression was lowered, but the protein levels of insulin-degrading enzyme and neprilysin were elevated. Diosmetin protects SH-SY5Y cells from endoplasmic reticulum (ER) stress response to AGEs by suppressing ER stress-induced glucose regulated protein 78, thereby downregulating protein kinase R-like endoplasmic reticulum kinase, eukaryotic initiation factor 2 α, activating transcription factor 4, and C/EBP homologous protein. Diosmetin-pretreated cells had a lower degree of apoptotic DNA fragmentation; this effect may be associated with B-cell lymphoma (Bcl) 2 protein upregulation, Bcl-2-associated X protein downregulation, and decreased activities of caspase-12/-9/-3. The reversion of diosmetin on the AGEs-induced harmful effects was similar to that produced by pioglitazone. The peroxisome proliferator-activated receptor (PPAR)γ antagonist T0070907 (5 μmol/L) abolished the beneficial effects of diosmetin on AGEs-treated SH-SY5Y cells, indicating the involvement of PPARγ. We conclude that diosmetin protects neuroblastoma cells against AGEs-induced ER injury via multiple mechanisms and may be a potential option for AD.

Parsing the Role of PPARs in Macrophage Processes

Cells are richly equipped with nuclear receptors, which act as ligand-regulated transcription factors. Peroxisome proliferator activated receptors (PPARs), members of the nuclear receptor family, have been extensively studied for their roles in development, differentiation, and homeostatic processes. In the recent past, there has been substantial interest in understanding and defining the functions of PPARs and their agonists in regulating innate and adaptive immune responses as well as their pharmacologic potential in combating acute and chronic inflammatory disease. In this review, we focus on emerging evidence of the potential roles of the PPAR subtypes in macrophage biology. We also discuss the roles of dual and pan PPAR agonists as modulators of immune cell function, microbial infection, and inflammatory diseases.

Regulation of Epigenetic Modifications in the Placenta during Preeclampsia: PPARγ Influences H3K4me3 and H3K9ac in Extravillous Trophoblast Cells

The aim of this study was to analyze the expression of peroxisome proliferator-activated receptor γ (PPARγ) and retinoid X receptor α (RxRα), a binding heterodimer playing a pivotal role in the successful trophoblast invasion, in the placental tissue of preeclamptic patients. Furthermore, we aimed to characterize a possible interaction between PPARγ and H3K4me3 (trimethylated lysine 4 of the histone H3), respectively H3K9ac (acetylated lysine 9 of the histone H3), to illuminate the role of histone modifications in a defective trophoblast invasion in preeclampsia (PE). Therefore, the expression of PPARγ and RxRα was analyzed in 26 PE and 25 control placentas by immunohistochemical peroxidase staining, as well as the co-expression with H3K4me3 and H3K9ac by double immunofluorescence staining. Further, the effect of a specific PPARγ-agonist (Ciglitazone) and PPARγ-antagonist (T0070907) on the histone modifications H3K9ac and H3K4me3 was analyzed in vitro. In PE placentas, we found a reduced expression of PPARγ and RxRα and a reduced co-expression with H3K4me3 and H3K9ac in the extravillous trophoblast (EVT). Furthermore, with the PPARγ-antagonist treated human villous trophoblast (HVT) cells and primary isolated EVT cells showed higher levels of the histone modification proteins whereas treatment with the PPARγ-agonist reduced respective histone modifications. Our results show that the stimulation of PPARγ-activity leads to a reduction of H3K4me3 and H3K9ac in trophoblast cells, but paradoxically decreases the nuclear PPARγ expression. As the importance of PPARγ, being involved in a successful trophoblast invasion has already been investigated, our results reveal a pathophysiologic connection between PPARγ and the epigenetic modulation via H3K4me3 and H3K9ac in PE.

Gene Expression Profiling of MicroRNAs in HPV-Induced Warts and Normal Skin

: Infection with the human papillomavirus (HPV) is a common occurrence among the global population, with millions of new cases emerging on an annual basis. Dysregulated microRNA (miRNA) expression is increasingly being identified to play a role in a number of different diseases, especially in the context of high-risk HPV infection. The present study investigated the miRNA expression profiles of warts induced by low-risk HPV. In warts, miR-27b, miR-24-1, miR-3654, miR-647, and miR-1914 were downregulated while miR-612 was upregulated compared to normal skin. Using miRTargetLink Human, experimentally supported evidence was obtained showing that miR-27b targeted the vascular endothelial growth factor C (VEGFC) and CAMP-responsive element binding protein 1 (CREB1) genes. The VEGFC and CREB1 genes have been reported to be involved in tumorigenesis and wart formation, respectively. Similarly, the oxidized low-density lipoprotein receptor 1 (OLR1) gene, which plays an important role in the humoral immunity of the skin, and the plexin D1 (PLXND1) gene, which is highly expressed in tumor vasculature, were both found to be common targets of miR-27b, miR-1914, and miR-612.

Sp1 contributes to radioresistance of cervical cancer through targeting G2/M cell cycle checkpoint CDK1

Background/aims

Radioresistance remains a significant obstacle in the therapy of cervical cancer, and the mechanism of it is still unclear. We aimed to investigate the role of specificity protein 1 (Sp1) in radioresistance of cervical cancer.

Methods

Sp1 was examined immunohistochemically on tissues from 36 human cervical cancer patients. We used RT-qPCR and Western blot to examine the expression of Sp1 in irradiated cervical cancer cell lines SiHa and HeLa. The role of Sp1 in radioresistance of cervical cancer cells was assessed by colony-formation assay and cell cycle analysis. Dual-luciferase reporter assay was performed to detect the downstream of Sp1.

Results

High Sp1 expression was positively correlated with advanced International Federation of Gynecology and Obstetrics (FIGO) stage, lymph node metastasis, and lymphovascular space invasion (LVSI) of cervical cancer. The expression of Sp1 was dose-dependently increased in irradiated cervical cancer cell lines at both mRNA and protein levels. Colony-formation assay showed that alteration of Sp1 expression affected the survival of cervical cancer cells with radiotherapy (RT) treatment. Knockdown of Sp1 significantly strengthened the cellular response to radiation by inducing G2/M arrest in cervical cancer cells. Overexpression of Sp1 significantly decreased G2/M arrest in cervical cancer cells, which was related to upregulation of CDK1 expression. Dual-luciferase reporter assay showed the direct effect of Sp1 on the transcriptional activation of CDK1.

Conclusion

Sp1 may contribute to radioresistance through inhibiting G2/M phase arrest by targeting CDK1, and be considered as a potential therapeutic target to promote the effect of RT for patients with cervical cancer.

Concomitant administration of radiation with eribulin improves the survival of mice harboring intracerebral glioblastoma

Glioblastoma is the most common and devastating type of malignant brain tumor. We recently found that eribulin suppresses glioma growth in vitro and in vivo and that eribulin is efficiently transferred into mouse brain tumors at a high concentration. Eribulin is a non‐taxane microtubule inhibitor approved for breast cancer and liposarcoma. Cells arrested in M‐phase by chemotherapeutic agents such as microtubule inhibitors are highly sensitive to radiation‐induced DNA damage. Several recent case reports have demonstrated the clinical benefits of eribulin combined with radiation therapy for metastatic brain tumors. In this study, we investigated the efficacy of a combined eribulin and radiation treatment on human glioblastoma cells. The glioblastoma cell lines U87MG, U251MG and U118MG, and SJ28 cells, a patient‐derived sphere culture cell line, were used to determine the radiosensitizing effect of eribulin using western blotting, flow cytometry and clonogenic assay. Subcutaneous and intracerebral glioma xenografts were generated in mice to assess the efficacy of the combined treatment. The combination of eribulin and radiation enhanced DNA damage in vitro. The clonogenic assay of U87MG demonstrated the radiosensitizing effect of eribulin. The concomitant eribulin and radiation treatment significantly prolonged the survival of mice harboring intracerebral glioma xenografts compared with eribulin or radiation alone (P < .0001). In addition, maintenance administration of eribulin after the concomitant treatment further controlled brain tumor growth. Aberrant microvasculature was decreased in these tumors. Concomitant treatment with eribulin and radiation followed by maintenance administration of eribulin may serve as a novel therapeutic strategy for glioblastomas.

Adiponectin promotes preadipocyte differentiation via the PPARγ pathway

According to the results of a preliminary study, it was hypothesized that the effects of adiponectin (APN) on the improvement of atherosclerosis may be associated with adipocyte differentiation and peroxisome proliferator‑activated receptor γ (PPARγ). The present study simulated the inflammatory environment of epicardial adipose tissue by stimulating mature adipocytes with lipopolysaccharide (LPS); subsequently, the differentiation of 3T3‑L1 preadipocytes was observed. 3T3‑L1 preadipocytes were infected with an adenovirus containing the human adiponectin gene apM1 (Ad‑apM1) and were co‑cultured with mature adipocytes stimulated with LPS. Differentiation into mature adipocytes was initiated using differentiation medium. After 8 days, an MTT assay was used to examine cell viability and oil red O staining was used to observe preadipocyte differentiation. In addition, the mRNA expression levels of monocyte chemoattractant protein‑1 (MCP‑1), interleukin (IL)‑6, IL‑8 and tumor necrosis factor α (TNF‑α) were examined by quantitative polymerase chain reaction, and the protein expression levels of PPARγ, CCAAT/enhancer binding protein α (C/EBPα) and preadipocyte factor‑1 (Pref‑1) were measured by western blotting. The results indicated that APN overexpression significantly increased preadipocyte differentiation and cell viability, inhibited MCP‑1, IL‑6, IL‑8 and TNF‑α expression, upregulated PPARγ and C/EBPα expression, and downregulated Pref‑1 under LPS stimulation. In addition, inhibition of PPARγ activity by T0070907 markedly attenuated the effects of APN overexpression. Taken together, the present study demonstrated that the effects of APN on the promotion of preadipocyte differentiation under inflammatory conditions may involve the PPARγ signaling pathway, and at least partly depends on upregulation of PPARγ expression.

Rosiglitazone enhances radiosensitivity by inhibiting repair of DNA damage in cervical cancer cells

Radiation therapy (RT) is one of the main treatment modalities for cervical cancer. Rosiglitazone (ROSI) has been reported to have antiproliferative effects against various types of cancer cells and also to induce antioxidant enzymes that can scavenge reactive oxygen species (ROS) and thereby modify radiosensitivity. Here, we explored the effect of ROSI on radiosensitivity and the underlying mechanisms in cervical cancer cells. Three cervical cancer cell lines (ME-180, HeLa, and SiHa) were used. The cells were pretreated with ROSI and then irradiated. Expression of proteins of interest was detected by western blot and immunofluorescence. Intracellular production of ROS was measured by H₂DCFDA. Radiosensitivity was assessed by monitoring clonogenic survival. Expression of antioxidant enzymes (catalase, superoxide dismutases) was increased by ROSI in HeLa and SiHa cells, but not in ME-180 cells. With ROSI pre-treatment, cell survival after irradiation remained unchanged in HeLa and SiHa cells, but decreased in ME-180 cells. Radiation-induced expression of γ-H2AX was increased and that of RAD51 was decreased by ROSI pre-treatment in ME-180 cells, but not in HeLa cells. ROSI increases radiosensitivity by inhibiting RAD51-mediated repair of DNA damage in some cervical cancer cell lines; therefore, ROSI is a potential inhibitor of RAD51 that can be used to enhance the effect of RT in the treatment of some cervical cancers.

A possible regulatory link between Twist 1 and PPARγ gene regulation in 3T3-L1 adipocytes

Background

Peroxisome proliferator-activated receptor γ (PPARγ) is a critical gene that regulates the function of adipocytes. Therefore, studies on the molecular regulation mechanism of PPARγ are important to understand the function of adipose tissue. Twist 1 is another important functional gene in adipose tissue, and hundreds of genes are regulated by Twist 1. The aim of this study was to investigate the regulation of Twist 1 and PPARγ expression in 3T3-L1 mature adipocytes.

Methods

We induced differentiation in 3T3-L1 preadipocytes and examined alterations in Twist 1 and PPARγ expression. We used the PPARγ agonist pioglitazone and the PPARγ antagonist T0070907 to investigate the effect of PPARγ on Twist 1 expression. In addition, we utilized retroviral interference and overexpression of Twist 1 to determine the effects of Twist 1 on PPARγ expression.

Results

The expression levels of Twist 1 and PPARγ were induced during differentiation in 3T3-L1 adipocytes. Application of either a PPARγ agonist (pioglitazone) or antagonist (T0070907) influenced Twist 1 expression, with up-regulation of Twist 1 under pioglitazone (1 μM, 24 h) and down-regulation of Twist 1 under T0070907 (100 μM, 24 h) exposure. Furthermore, the retroviral interference of Twist 1 decreased the protein and mRNA expression of PPARγ, while Twist 1 overexpression had the opposite effect.

Conclusions

There was a possible regulatory link between Twist 1 and PPARγ in 3T3-L1 mature adipocytes. This regulatory link enhanced the regulation of PPARγ and may be a functional mechanism of Twist 1 regulation of adipocyte physiology and pathology.

Promotion of mitotic catastrophe via activation of PTEN by paclitaxel with supplement of mulberry water extract in bladder cancer cells

Paclitaxel is a mitotic inhibitor used in cancer chemotherapy. Mulberry fruit is rich in phenolic compounds and flavonoids and exhibits chemopreventive activities. In this study, mulberry water extract (MWE) was used as a supplement to synergize with the effects of paclitaxel in the treatment of the TSGH 8301 human bladder cancer cell line. Treatment with paclitaxel combined with MWE (paclitaxel/MWE) enhanced the cytotoxicity of paclitaxel and induced severe G2/M arrest, mitotic catastrophe and subsequent apoptosis, as shown by MTT assay, HE staining and flow cytometry analyses. Differences in the expression and activation of Aurora A and Plk1between cells treated with paclitaxel/MWE and paclitaxel alone suggested that the combined treatment caused a defect in the early steps of cytokinesis. Paclitaxel/MWE decreased EEA1immunofluorescence staining and increased the expression of PTEN, indicating that the regimen inhibited the formation of the recycling endosome, which is required for cytokinesis. Paclitaxel/MWE also retarded tumor growth in a TSGH 8301 xenograft model via activation of PTEN and Caspase 3. These data demonstrated a synergistic effect on the anticancer efficacy of paclitaxel through MWE supplementation by promoting mitotic catastrophe through the activation of PTEN, providing a novel and effective therapeutic option for bladder cancer treatment strategies.

Valproic acid protects against haemorrhagic shock-induced signalling changes via PPARγ activation in an in vitro model

BACKGROUND AND PURPOSE

Valproic acid (VPA), a widely used epilepsy and bipolar disorder treatment, provides acute protection against haemorrhagic shock-induced mortality in a range of in vivo models through an unknown mechanism. In the liver, this effect occurs with a concomitant protection against a decrease in GSK3β-Ser(9) phosphorylation. Here, we developed an in vitro model to investigate this protective effect of VPA and define a molecular mechanism.

EXPERIMENTAL APPROACH

The human hepatocarcinoma cell line (Huh7) was exposed to conditions occurring during haemorrhagic shock (hypoxia, hypercapnia and hypothermia) to investigate the changes in GSK3β-Ser(9) phosphorylation for a 4 h period following treatment with VPA, related congeners, PPAR agonists, antagonists and siRNA.

KEY RESULTS

Huh7 cells undergoing combined hypoxia, hypercapnia, and hypothermia reproduced the reduced GSK3β-Ser(9) phosphorylation shown in vivo during haemorrhagic shock, and this change was blocked by VPA. The protective effect occurred through upstream PTEN and Akt signalling, and prevented downstream β-catenin degradation while increasing histone 2/3 acetylation. This effect was reproduced by several VPA-related compounds with known PPARγ agonist activity, independent of histone deacetylase (HDAC) inhibitory activity. Specific pharmacological inhibition (by T0070907) or knockdown of PPARγ blocked the protective effect of VPA against these signalling changes and apoptosis. In addition, specific activation of PPARγ using ciglitazone reproduced the changes induced by VPA in haemorrhagic shock-like conditions.

CONCLUSION AND IMPLICATIONS

Changes in GSK3β-Ser(9) phosphorylation in in vivo haemorrhagic shock models can be modelled in vitro, and this has identified a role for PPARγ activation in the protective role of VPA.

Targeted Therapies in Adult B-Cell Malignancies

B-lymphocytes are programmed for the production of immunoglobulin (Ig) after antigen presentation, in the context of T-lymphocyte control within lymphoid organs. During this differentiation/activation process, B-lymphocytes exhibit different restricted or common surface markers, activation of cellular pathways that regulate cell cycle, metabolism, proteasome activity, and protein synthesis. All molecules involved in these different cellular mechanisms are potent therapeutic targets. Nowadays, due to the progress of the biology, more and more targeted drugs are identified, a situation that is correlated with an extended field of the targeted therapy. The full knowledge of the cellular machinery and cell-cell communication allows making the best choice to treat patients, in the context of personalized medicine. Also, focus should not be restricted to the immediate effects observed as clinical endpoints, that is, response rate, survival markers with conventional statistical methods, but it should consider the prediction of different clinical consequences due to other collateral drug targets, based on new methodologies. This means that new reflection and new bioclinical follow-up have to be monitored, particularly with the new drugs used with success in B-cell malignancies. This review discussed the principal aspects of such evident bioclinical progress.

Antiproliferative effects and molecular mechanisms of troglitazone in human cervical cancer in vitro

We investigated the effects of troglitazone on human cervical cancer SiHa cells and its mechanisms of action. SiHa cells were incubated with different concentrations of troglitazone (100, 200, or 400 μg/mL) for 24, 48, and 72 hours. Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT) assay; cell cycle and apoptosis were detected by flow cytometry; and morphology of SiHa cells was observed under an inverted microscope. pcDNA3.1 and pcDNA3.1-Skp2 plasmids were constructed and then transfected into SiHa cells. Protein expression was analyzed by Western blotting. Troglitazone inhibited the proliferation of SiHa cells in a time- and concentration-dependent manner. Troglitazone caused G0/1 phase arrest but failed to reduce apoptosis in SiHa cells. Troglitazone significantly increased expression of p27 but decreased Skp2 expression. Skp2 overexpression inhibited the role of troglitazone in increasing expression of p27, and the cell cycle inhibitory effect of troglitazone. Troglitazone can inhibit SiHa cell viability by affecting cell cycle distribution but not apoptosis, and Skp2 and p27 may play a critical role.