EGFR/MDM2 signaling promotes NF-κB activation via PPARγ degradation

FK506-binding proteins: Emerging target and therapeutic opportunity in multiple tumors

The FK506-binding protein (FKBP) family plays a key role in a variety of tumors and is involved in the regulation of important signaling pathways including AKT, NF-κB and p53, which affects cell proliferation, migration, and multiple cell death modes. Here, we summarize the findings that different FKBP family members exhibit dual functions of promoting or inhibiting tumorigenesis in different types of tumors. The expression levels of FKBP family members are closely related to the prognosis of patients, thus might be used as potential diagnostic and prognostic biomarkers. In the future, it is necessary to combine single-cell sequencing to resolve the spatial distribution of FKBP isoforms, develop clinical validation to promote the translation from molecular mechanism to precision therapy.

TBB inhibits CK2/PD-L1/EGFR pathway-mediated tumor progression

The expression of PD-L1 on cancer cells facilitates tumor immune escape by binding to PD-1 on T cells, thereby inhibiting T cell activity. However, the role of intracellular PD-L1 signaling in tumor progression remains unclear. In this study, we demonstrate that CK2 induces PD-L1 phosphorylation at Thr-285, which enhances PD-L1 protein stability. This phosphorylation disrupts the interaction between LC3B and PD-L1, inhibiting PD-L1 degradation via autophagy. Furthermore, PD-L1-T285 phosphorylation promotes EGFR binding to PD-L1, leading to activation of EGFR downstream signaling. This activation drives non-small cell lung cancer (NSCLC) cell proliferation, migration, invasion, and tumor growth. Conversely, CK2 depletion or treatment with a CK2 inhibitor reversed these effects. Our findings reveal a novel mechanism by which the CK2/PD-L1/EGFR pathway promotes tumor progression.

Anticancer activity of thymoquinone in non-small cell lung cancer and possible involvement of PPAR-γ pathway

PURPOSE

Thymoquinone (TQ) is an ingredient of Nigella sativa and Cisplatin (CDDP) is the most active chemotherapeutic agent in lung cancer. The objective of this study was to assess the anticancer effects of TQ in non-small cell lung cancer (NSCLC) cells, and its effect on the peroxisome proliferator-activated receptor gamma (PPAR-γ) pathway.

METHODS

Annexin-V FITC assay was used in the NCI-H460 cell line for apoptosis. The mRNA expression of PPAR-γ, P53, BCL-2, Retinoblastoma (Rb), Cyclin-D1, RELA, Tumor necrosis Factor alpha and in a dose-dependent manner TQ activated caspases 9, 8, 7, and 3 were examined using quantitative real-time reverse transcriptase polymerase chain reaction.

RESULTS

PPAR-γ protein levels elevated in all treatment groups, especially in the CDDP + TQ group as observed in mRNA results. In the CDDP + TQ + IR group, the reduction of NF-κB pathway, which provides survival and growth signaling, confirms the potential of this treatment in lung cancer treatment approach similar to p53, Rb, and PPAR-γ results. When the effect of treatment on the viability of NSCLC cells was assessed with flow cytometry analyzes, TQ alone supported death compared to control, cell viability also decreased in the CDDP or IR groups to which TQ was added.

CONCLUSION

As a result, combined therapy of TQ, CDDP, and IR have been shown to increase apoptosis by sensitizing NSCLC cells to IR. These in vitro results are the basis because they demonstrate that it may be useful to include TQ in combined NSCLC cell treatments to reduce tumor progression.

Nuclear epidermal growth factor receptor (nEGFR) in clinical treatment

The epidermal growth factor receptor (EGFR) is a recognized target in tumor treatment. While there is significant focus on inhibiting membrane EGFR and its downstream signaling activation, the ectopic accumulation of EGFR, particularly nuclear EGFR (nEGFR), has been implicated in tumor-associated activities and associated with poor prognosis. Within the nucleus, nEGFR functions as a transcriptional regulator to modulate transcriptional landscape and exerts tyrosine kinase activity to phosphorylate nuclear proteins and subsequently influences DNA repair, cell cycle, proliferation, and resistance to radiotherapy and chemotherapy. The nuclear localization of EGFR involves the internalization, subcellular trafficking, and nuclear envelope shuttling of membrane EGFR. Given the challenges of delivering drugs to the nucleus for targeting nEGFR, understanding the molecules affecting the translocation process is crucial for novel insights. This review initially explores the association between nEGFR expression and clinical outcomes and then elucidates how nEGFR fulfills its regulatory role within the nucleus. Subsequently, the mechanisms governing EGFR nuclear translocation and potential therapeutic targets during this process are summarized, highlighting avenues to target nEGFR as an innovative strategy in tumor treatment.

Gliotoxin triggers cell death through multifaceted targeting of cancer-inducing genes in breast cancer therapy

Fungal secondary metabolites have a long history of contributing to pharmaceuticals, notably in the development of antibiotics and immunosuppressants. Harnessing their potent bioactivities, these compounds are now being explored for cancer therapy, by targeting and disrupting the genes that induce cancer progression. The current study explores the anticancer potential of gliotoxin, a fungal secondary metabolite, which encompasses a multi-faceted approach integrating computational predictions, molecular dynamics simulations, and comprehensive experimental validations. In-silico studies have identified potential gliotoxin targets, including MAPK1, NFKB1, HIF1A, TDP1, TRIM24, and CTSD which are involved in critical pathways in cancer such as the NF-κB signaling pathway, MAPK/ERK signaling pathway, hypoxia signaling pathway, Wnt/β-catenin pathway, and other essential cellular processes. The gene expression analysis results indicated all the identified targets are overexpressed in various breast cancer subtypes. Subsequent molecular docking and dynamics simulations have revealed stable binding of gliotoxin with TDP1 and HIF1A. Cell viability assays exhibited a dose-dependent decreasing pattern with its remarkable IC50 values of 0.32, 0.14, and 0.53 μM for MDA-MB-231, MDA-MB-468, and MCF-7 cells, respectively. Likewise, in 3D tumor spheroids, gliotoxin exhibited a notable decrease in viability indicating its effectiveness against solid tumors. Furthermore, gene expression studies using Real-time PCR revealed a reduction of expression of cancer-inducing genes, MAPK1, HIF1A, TDP1, and TRIM24 upon gliotoxin treatment. These findings collectively underscore the promising anticancer potential of gliotoxin through multi-targeting cancer-promoting genes, positioning it as a promising therapeutic option for breast cancer.

BRD4 promotes gouty arthritis through MDM2-mediated PPARγ degradation and pyroptosis

BACKGROUND

Gouty arthritis (GA) is characterized by monosodium urate (MSU) crystal accumulation that instigates NLRP3-mediated pyroptosis; however, the underlying regulatory mechanisms have yet to be fully elucidated. The present research endeavors to elucidate the regulatory mechanisms underpinning this MSU-induced pyroptotic cascade in GA.

METHODS

J774 cells were exposed to lipopolysaccharide and MSU crystals to establish in vitro GA models, whereas C57BL/6 J male mice received MSU crystal injections to mimic in vivo GA conditions. Gene and protein expression levels were evaluated using real-time quantitative PCR, Western blotting, and immunohistochemical assays. Inflammatory markers were quantified via enzyme-linked immunosorbent assays. Pyroptosis was evaluated using immunofluorescence staining for caspase-1 and flow cytometry with caspase-1/propidium iodide staining. The interaction between MDM2 and PPARγ was analyzed through co-immunoprecipitation assays, whereas the interaction between BRD4 and the MDM2 promoter was examined using chromatin immunoprecipitation and dual-luciferase reporter assays. Mouse joint tissues were histopathologically evaluated using hematoxylin and eosin staining.

RESULTS

In GA, PPARγ was downregulated, whereas its overexpression mitigated NLRP3 inflammasome activation and pyroptosis. MDM2, which was upregulated in GA, destabilized PPARγ through the ubiquitin-proteasome degradation pathway, whereas its silencing attenuated NLRP3 activation by elevating PPARγ levels. Concurrently, BRD4 was elevated in GA and exacerbated NLRP3 activation and pyroptosis by transcriptionally upregulating MDM2, thereby promoting PPARγ degradation. In vivo experiments showed that BRD4 silencing ameliorated GA through this MDM2-PPARγ-pyroptosis axis.

CONCLUSION

BRD4 promotes inflammation and pyroptosis in GA through MDM2-mediated PPARγ degradation, underscoring the therapeutic potential of targeting this pathway in GA management.

Dual function of activated PPARγ by ligands on tumor growth and immunotherapy

As one of the peroxisome-proliferator-activated receptors (PPARs) members, PPARγ is a ligand binding and activated nuclear hormone receptor, which is an important regulator in metabolism, proliferation, tumor progression, and immune response. Increased evidence suggests that activation of PPARγ in response to ligands inhibits multiple types of cancer proliferation, metastasis, and tumor growth and induces cell apoptosis including breast cancer, colon cancer, lung cancer, and bladder cancer. Conversely, some reports suggest that activation of PPARγ is associated with tumor growth. In addition to regulating tumor progression, PPARγ could promote or inhibit tumor immunotherapy by affecting macrophage differentiation or T cell activity. These controversial findings may be derived from cancer cell types, conditions, and ligands, since some ligands are independent of PPARγ activity. Therefore, this review discussed the dual role of PPARγ on tumor progression and immunotherapy.

The KDM5 inhibitor PBIT reduces proliferation of castration-resistant prostate cancer cells via cell cycle arrest and the induction of senescence

The compound 2-4(4-methylphenyl)-1,2-benzisothiazol-3(2H)-one (PBIT) is an inhibitor of the KDM5 family of lysine-specific histone demethylases that has been suggested as a lead compound for cancer therapy. The goal of this study was to explore the effects of PBIT within human prostate cancers. Micromolar concentrations of PBIT altered proliferation of castration-sensitive LNCaP and castration-resistant C4-2B, LNCaP-MDV3100 and PC-3 human prostate cancer cell lines. We then characterized the mechanism underlying the anti-proliferative effects of PBIT within the C4-2B and PC-3 cell lines. Data from Cell Death ELISAs suggest that PBIT does not induce apoptosis within C4-2B or PC-3 cells. However, PBIT did increase the amount of senescence associated beta-galactosidase. PBIT also altered cell cycle progression and increased protein levels of the cell cycle protein p21. PC-3 and C4-2B cells express varying amounts of KDM5A, KDM5B, and KDM5C, the therapeutic targets of PBIT. siRNA-mediated knockdown studies suggest that inhibition of multiple KDM5 isoforms contribute to the anti-proliferative effect of PBIT. Furthermore, combination treatments involving PBIT and the PPARγ agonist 15-deoxy-Δ-12, 14 -prostaglandin J2 (15d-PGJ₂) also reduced PC-3 cell proliferation. Together, these data strongly suggest that PBIT significantly reduces the proliferation of prostate cancers via a mechanism that involves cell cycle arrest and senescence.

The prognostic and immunological role of FKBP1A in an integrated muti-omics cancers analysis, especially lung cancer

BACKGROUND AND AIM

FKBP1A, a gene encoding the FK506-binding protein 1A, has emerged as a significant player in cancer progression and prognosis. This study aimed to comprehensively investigate the multifaceted role of FKBP1A in cancer, focusing on its differential expression patterns, prognostic implications, genetic alterations, and associations with the tumor microenvironment.

METHODS AND RESULTS

Using large-scale datasets, including GTEx, TCGA, HPA, and cBioPortal, we analyzed FKBP1A expression across normal tissues and various cancer types. Our findings revealed that FKBP1A exhibited aberrant upregulation in most human cancers, making it a potential biomarker for malignancy. Moreover, FKBP1A expression correlated with poor overall survival, disease-specific survival, disease-free interval, and progression-free interval in several cancers, indicating its prognostic significance. Genetic alteration analysis showed that FKBP1A gene amplification was prevalent, particularly in ovarian cancer. Furthermore, FKBP1A expression was associated with tumor mutational burden and microsatellite instability, highlighting its potential involvement in tumor-immune response. Notably, FKBP1A expression positively correlated with stromal and immune cell scores, suggesting its role in shaping the tumor microenvironment. Additionally, according to the functional enrichment analysis, experimental validation in lung adenocarcinoma confirmed the role of FKBP1A through the regulation of EGFR signaling by apoptosis, which is consistent with drug sensitivity analysis to some extent.

CONCLUSION

In conclusion, FKBP1A exhibits differential expression in cancer, serves as a prognostic indicator, undergoes genetic alterations, and influences the tumor-immune microenvironment. These findings shed light on the multifaceted role of FKBP1A in cancer development and progression, suggesting its potential as a therapeutic target and guidance of clinical drugs selection, and provide valuable insights into patient prognosis for interventions based on pharmaceuticals.

Targeting the retinoic acid signaling pathway as a modern precision therapy against cancers

Retinoic acid (RA) is a vital metabolite derived from vitamin A. RA plays a prominent role during development, which helps in embryological advancement and cellular differentiation. Mechanistically, RA binds to its definite nuclear receptors including the retinoic acid receptor and retinoid X receptor, thus triggering gene transcription and further consequences in gene regulation. This functional heterodimer activation later results in gene activation/inactivation. Several reports have been published related to the detailed embryonic and developmental role of retinoic acids and as an anti-cancer drug for specific cancers, including acute promyelocytic leukemia, breast cancer, and prostate cancer. Nonetheless, the other side of all-trans retinoic acid (ATRA) has not been explored widely yet. In this review, we focused on the role of the RA pathway and its downstream gene activation in relation to cancer progression. Furthermore, we explored the ways of targeting the retinoic acid pathway by focusing on the dual role of aldehyde dehydrogenase (ALDH) family enzymes. Combination strategies by combining RA targets with ALDH-specific targets make the tumor cells sensitive to the treatment and improve the progression-free survival of the patients. In addition to the genomic effects of ATRA, we also highlighted the role of ATRA in non-canonical mechanisms as an immune checkpoint inhibitor, thus targeting the immune oncological perspective of cancer treatments in the current era. The role of ATRA in activating independent mechanisms is also explained in this review. This review also highlights the current clinical trials of ATRA in combination with other chemotherapeutic drugs and explains the future directional insights related to ATRA usage.

PPARγ agonist pioglitazone enhances colorectal cancer immunotherapy by inducing PD-L1 autophagic degradation

Blockade of PD-1/PD-L1 immune checkpoint could be an effective antitumor strategy for multiple types of cancer, but it is low response rate for colorectal cancer patients with unclear mechanism. Here we found that PPARγ agonist pioglitazone could reduce PD-L1 protein levels without effect on its gene expression. Further analysis showed that pioglitazone induced PD-L1 autophagic degradation in a PPARγ-dependent manner. Pioglitazone promoted PD-L1 translocation to lysosome by immunofluorescence analysis, which was associated with the increased binding of PPARγ to PD-L1. Moreover the combined pioglitazone with PD-1 antibody enhanced colorectal tumor immunotherapy, which was involved in reduced PD-L1 levels and increased CD8⁺ T cells. These findings suggest that PPARγ agonist could induce PD-L1 autophagic degradation resulting in increased colorectal tumor immunotherapy.

Emerging Role of Plant-Based Dietary Components in Post-Translational Modifications Associated with Colorectal Cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide. Its main modifiable risk factors are diet, alcohol consumption, and smoking. Thus, the right approach through lifestyle changes may lead to its prevention. In fact, some natural dietary components have exhibited chemopreventive activity through modulation of cellular processes involved in CRC development. Although cancer is a multi-factorial process, the study of post-translational modifications (PTMs) of proteins associated with CRC has recently gained interest, as inappropriate modification is closely related to the activation of cell signalling pathways involved in carcinogenesis. Therefore, this review aimed to collect the main PTMs associated with CRC, analyse the relationship between different proteins that are susceptible to inappropriate PTMs, and review the available scientific literature on the role of plant-based dietary compounds in modulating CRC-associated PTMs. In summary, this review suggested that some plant-based dietary components such as phenols, flavonoids, lignans, terpenoids, and alkaloids may be able to correct the inappropriate PTMs associated with CRC and promote apoptosis in tumour cells.

LncRNA SNHG1 Facilitates Tumor Proliferation and Represses Apoptosis by Regulating PPARγ Ubiquitination in Bladder Cancer

Simple Summary

Our study elucidated that SNHG1 promotes MDM2 expression by binding to miR-9-3p to promote PPARγ ubiquitination and downregulate PPARγ expression and that SNHG1 plays an important role in bladder cancer and provides a potential therapeutic target for bladder cancer.

Abstract

Background: Long noncoding RNAs regulate various biological effects in the progression of cancers. We found that the expression of SNHG1 was significantly up-regulated in bladder cancer after analyzing data obtained from TCGA and GEO. However, the potential role of SNHG1 remains to be investigated in bladder cancer. It was validated that SNHG1 was overexpressed in bladder cancer tissues detected by qRT-PCR and FISH, which was also associated with poor clinical outcome. Additionally, SNHG1 was verified to facilitate tumor proliferation and repress apoptosis in vitro and in vivo. Results: SNHG1 could act as a competitive endogenous RNA and decrease the expression of murine double minute 2 (MDM2) by sponging microRNA-9-3p. Furthermore, MDM2 induced ubiquitination and degradation of PPARγ that contributed to the development of bladder cancer. Conclusions: the study elucidated that SNHG1 played an important role in bladder cancer and provided a potential therapeutic target for bladder cancer.

SIRT1/PGC-1α/PPAR-γ Correlate With Hypoxia-Induced Chemoresistance in Non-Small Cell Lung Cancer

Resistance is the major cause of treatment failure and disease progression in non-small cell lung cancer (NSCLC). There is evidence that hypoxia is a key microenvironmental stress associated with resistance to cisplatin, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), and immunotherapy in solid NSCLCs. Numerous studies have contributed to delineating the mechanisms underlying drug resistance in NSCLC; nevertheless, the mechanisms involved in the resistance associated with hypoxia-induced molecular metabolic adaptations in the microenvironment of NSCLC remain unclear. Studies have highlighted the importance of posttranslational regulation of molecular mediators in the control of mitochondrial function in response to hypoxia-induced metabolic adaptations. Hypoxia can upregulate the expression of sirtuin 1 (SIRT1) in a hypoxia-inducible factor (HIF)-dependent manner. SIRT1 is a stress-dependent metabolic sensor that can deacetylate some key transcriptional factors in both metabolism dependent and independent metabolic pathways such as HIF-1α, peroxisome proliferator-activated receptor gamma (PPAR-γ), and PPAR-gamma coactivator 1-alpha (PGC-1α) to affect mitochondrial function and biogenesis, which has a role in hypoxia-induced chemoresistance in NSCLC. Moreover, SIRT1 and HIF-1α can regulate both innate and adaptive immune responses through metabolism-dependent and -independent ways. The objective of this review is to delineate a possible SIRT1/PGC-1α/PPAR-γ signaling-related molecular metabolic mechanism underlying hypoxia-induced chemotherapy resistance in the NSCLC microenvironment. Targeting hypoxia-related metabolic adaptation may be an attractive therapeutic strategy for overcoming chemoresistance in NSCLC.

RETRACTED: MicroRNA-498 disturbs the occurrence and aggression of colon cancer through targeting MDM2 to mediate PPARγ ubiquitination

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the reliability of this article that shares several characteristics with other articles in the eyebrow family of publications, tabulated here (https://docs.google.com/spreadsheets/d/149EjFXVxpwkBXYJOnOHb6RhAqT4a2llhj9LM60MBffM/edit#gid=0). In addition, Fig. 5A appears to show a digital composition of xenografted tumors. The journal requested the corresponding author comment on these concerns and provide the raw data. However the authors were not able to satisfactorily fulfil this request and therefore the Editor-in-Chief decided to retract the article.

PPARδ is a regulator of autophagy by its phosphorylation

In response to nutrient deficiency, autophagy degrades cytoplasmic materials and organelles in lysosomes, which is nutrient recycling, whereas activation of EGFR mediates autophagy suppression in response to growth factors. It is unclear whether PPARδ could be the regulator of autophagy in response to active EGFR. Here we found that EGFR induced PPARδ phosphorylation at tyrosine-108 leading to increased binding of LC3 to PPARδ by its LIR (LC3 interacting region) motif, consequently, inhibited autophagic flux. Conversely, EGFR inhibitor treatment reversed this event. Furthermore, EGFR-mediated PPARδ phosphorylation at tyrosine-108 led to autophagy inhibition and tumor growth. These findings suggest that PPARδ serves as a regulator of autophagy by its phosphorylation.

Antitumor Effects and the Compatibility Mechanisms of Herb Pair Scleromitrion diffusum (Willd.) R. J. Wang-Sculellaria barbata D. Don

Herb pair Scleromitrion diffusum (Willd.) R. J. Wang (HD) and Scutellaria barbata D. Don (SB) has been most frequently used for cancer treatment in traditional Chinese medicine. This study aimed to explore the in vitro and in vivo antitumor effects of HD-SB extract and to elucidate the underlying compatibility mechanisms. HD, SB, and HD-SB extracts were prepared, and the components were detected by ultraperformance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry method. The in vitro antitumor effects of various concentrations of these extract were detected on several tumor cell lines using MTS assay. The in vivo antitumor effects were evaluated in Panc28 cells–bearing nude mice model. The compatibility mechanisms of herb pair HD-SB were evaluated based on the systems pharmacology strategy and then validated by cellular experiments. HD-SB extract was demonstrated to inhibit the proliferation of the cancer cell lines dose dependently by MTS assay. In vivo antitumor effects of HD-SB were much more potent than either of the two single herbs in Panc28 xenograft mice model. A total 29 active ingredients involved in antitumor effects were selected from HD and SB, and the “herb–composition–target–disease” network was constructed. Then, 58 cancer-related targets and 66 KEGG pathways were identified, and PTGS2-, HSP90-, EGFR-, MMP2-, PPARγ-, and GSTP-mediated pathways were predicted to be the antitumor mechanisms of HD-SB. The cellular experiments showed that HD-SB significantly induced cancer cell apoptosis, decreased p-EGFR, HSP90 and bcl-2 expressions, and increased PPARγ, bax, cleaved caspase 3, cleaved PARP, p-AKT, and p-PI3K expressions compared with HD or SB treatment. Our study showed that HD-SB inhibited tumor growth both in vitro and in vivo, which might be related with apoptosis induction via the EGFR/PPARγ/PI3K/AKT pathway.

TNBG-5602, a novel derivative of quinoxaline, inhibits liver cancer growth via upregulating peroxisome proliferator-activated receptor γ in vitro and in vivo

Objectives

TNBG-5602 is a newly synthesized compound with an isoquinoline structure. In the present study, we demonstrated the anticancer effect of TNBG-5602 in in-vitro and in-vivo models and investigated its possible anticancer mechanism.

Methods

The antiproliferation effect of TNBG-5602 in vitro was evaluated in human liver cancer cell line QGY-7701. The acute toxicity of TNBG-5602 was evaluated in mice. The anticancer activity of TNBG-5602 in vivo was assessed in a xenograft model of human liver cancer cell line QGY-7701.

Key findings

The results of CCK-8 assay showed that TNBG-5602 can effectively inhibit the proliferation of liver cancer cells in vitro. The acute toxicity test in mice showed that the LD50 of TNBG-5602 was 172 mg/kg. In a xenograft liver cancer model, TNBG-5602 could remarkably inhibit the growth of tumours. During in-vitro and in-vivo studies, we noted that TNBG-5602 could induce lipid accumulation in cancer cells and tissues. Further study indicated that the anticancer effect of TNBG-5602 may be exerted through activating peroxisome proliferator-activated receptor γ (PPARγ) and downregulating proliferating cell nuclear antigen (PCNA).

Conclusions

Our results suggested that TNBG-5602 might exert potent anticancer activity through increasing the expression of PPARγ.

The role of MDM2 amplification and overexpression in therapeutic resistance of malignant tumors

The MDM2 protein encoded by the mouse double minute 2 (MDM2) gene is the primary negative regulatory factor of the p53 protein. MDM2 can ligate the p53 protein via its E3 ubiquitin ligase, and the ubiquitinated p53 can be transferred to the cytoplasm and degraded by proteasomes. Therefore, MDM2 can maintain the stability of p53 signaling pathway. MDM2 amplification has been detected in many human malignancies, including lung cancer, colon cancer and other malignancies. MDM2 overexpression is associated with chemotherapeutic resistance in human malignancies. The mechanisms of chemotherapeutic resistance by MDM2 overexpression mainly include the p53–MDM2 loop-dependent and p53–MDM2 loop-independent pathways. But the role of MDM2 overexpression in tyrosine kinase inhibitors resistance remains to be further study. This paper reviews the possible mechanisms of therapeutic resistance of malignancies induced by MDM2 amplification and overexpression, including chemotherapy, radiotherapy, targeted agents and hyperprogressive disease of immunotherapy. Besides, MDM2-targeted therapy may be a potential new strategy for treating advanced malignancies.

Sonic hedgehog signaling instigates high-fat diet-induced insulin resistance by targeting PPARγ stability

Obesity is a major risk for patients with chronic metabolic disorders including type 2 diabetes. Sonic hedgehog (Shh) is a morphogen that regulates the pancreas and adipose tissue formation during embryonic development. Peroxisome proliferator-activated receptor γ (PPARγ) is a member of the nuclear receptor superfamily and one of the most important regulators of insulin action. Here, we evaluated the role and mechanism of Shh signaling in obesity-associated insulin resistance and characterized its effect on PPARγ. We showed that Shh expression was up-regulated in subcutaneous fat from obese mice. In differentiated 3T3-L1 and primary cultured adipocytes from rats, recombinant Shh protein and SAG (an agonist of Shh signaling) activated an extracellular signal-regulated kinase (ERK)-dependent noncanonical pathway and induced PPARγ phosphorylation at serine 112, which decreased PPARγ activity. Meanwhile, Shh signaling degraded PPARγ protein via binding of PPARγ to neural precursor cell-expressed developmentally down-regulated protein 4-1 (NEDD4-1). Furthermore, vismodegib, an inhibitor of Shh signaling, attenuated ERK phosphorylation induced by a high fat diet (HFD) and restored PPARγ protein level, thus ameliorating glucose intolerance and insulin resistance in obese mice. Our finding suggests that Shh in subcutaneous fat decreases PPARγ activity and stability via activation of an ERK-dependent noncanonical pathway, resulting in impaired insulin action. Inhibition of Shh may serve as a potential therapeutic approach to treat obesity-related diabetes.

EGFR inhibitors from cancer to inflammation: Discovery of 4-fluoro-N-(4-(3-(trifluoromethyl)phenoxy)pyrimidin-5-yl)benzamide as a novel anti-inflammatory EGFR inhibitor

EGFR inhibitors are well-known as anticancer agents. Quite differently, we report our effort to develop EGFR inhibitors as anti-inflammatory agents. Pyrimidinamide EGFR inhibitors eliciting low micromolar IC₅₀ and the structurally close non-EGFR inhibitor urea analog were synthesized. Comparing their nitric oxide (NO) production inhibitory activity in peritoneal macrophages and RAW 246.7 macrophages indicated that their anti-inflammatory activity in peritoneal macrophages might be a sequence of EGFR inhibition. Further evaluations proved that compound 4d significantly and dose-dependently inhibits LPS-induced iNOS expression and IL-1β, IL-6, and TNF-α production via NF-κB inactivation in peritoneal macrophages. Compound 4d might serve as a lead compound for development of a novel class of anti-inflammatory EGFR inhibitors.

The E3 ubiquitin ligase TRIM25 regulates adipocyte differentiation via proteasome-mediated degradation of PPARγ

Peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-dependent transcription factor that regulates adipocyte differentiation and glucose homeostasis. The transcriptional activity of PPARγ is regulated not only by ligands but also by post-translational modifications (PTMs). In this study, we demonstrate that a novel E3 ligase of PPARγ, tripartite motif-containing 25 (TRIM25), directly induced the ubiquitination of PPARγ, leading to its proteasome-dependent degradation. During adipocyte differentiation, both TRIM25 mRNA and protein expression significantly decreased and negatively correlated with the expression of PPARγ. The stable expression of TRIM25 reduced PPARγ protein levels and suppressed adipocyte differentiation in 3T3-L1 cells. In contrast, the specific knockdown of TRIM25 increased PPARγ protein levels and stimulated adipocyte differentiation. Furthermore, TRIM25-knockout mouse embryonic fibroblasts (MEFs) exhibited an increased adipocyte differentiation capability compared with wild-type MEFs. Taken together, these data indicate that TRIM25 is a novel E3 ubiquitin ligase of PPARγ and that TRIM25 is a novel target for PPARγ-associated metabolic diseases.

The Involvement of PPARs in the Peculiar Energetic Metabolism of Tumor Cells

Energy homeostasis is crucial for cell fate, since all cellular activities are strongly dependent on the balance between catabolic and anabolic pathways. In particular, the modulation of metabolic and energetic pathways in cancer cells has been discussed in some reports, but subsequently has been neglected for a long time. Meanwhile, over the past 20 years, a recovery of the study regarding cancer metabolism has led to an increasing consideration of metabolic alterations in tumors. Cancer cells must adapt their metabolism to meet their energetic and biosynthetic demands, which are associated with the rapid growth of the primary tumor and colonization of distinct metastatic sites. Cancer cells are largely dependent on aerobic glycolysis for their energy production, but are also associated with increased fatty acid synthesis and increased rates of glutamine consumption. In fact, emerging evidence has shown that therapeutic resistance to cancer treatment may arise from the deregulation of glucose metabolism, fatty acid synthesis, and glutamine consumption. Cancer cells exhibit a series of metabolic alterations induced by mutations that lead to a gain-of-function of oncogenes, and a loss-of-function of tumor suppressor genes, including increased glucose consumption, reduced mitochondrial respiration, an increase of reactive oxygen species, and cell death resistance; all of these are responsible for cancer progression. Cholesterol metabolism is also altered in cancer cells and supports uncontrolled cell growth. In this context, we discuss the roles of peroxisome proliferator-activated receptors (PPARs), which are master regulators of cellular energetic metabolism in the deregulation of the energetic homeostasis, which is observed in cancer. We highlight the different roles of PPAR isotypes and the differential control of their transcription in various cancer cells.

Peroxisome proliferator-activated receptors (PPARs) are potential drug targets for cancer therapy

Peroxisome-proliferator-activated receptors (PPARs) are nuclear hormone receptors including PPARα, PPARδ and PPARγ, which play an important role in regulating cancer cell proliferation, survival, apoptosis, and tumor growth. Activation of PPARs by endogenous or synthetic compounds regulates tumor progression in various tissues. Although each PPAR isotype suppresses or promotes tumor development depending on the specific tissues or ligands, the mechanism is still unclear. In this review, we summarized the regulative mechanism of PPARs on cancer progression.

Inhibitor of growth-4 is a potential target for cancer therapy

The inhibitor of growth-4 (ING-4) belongs to the inhibitor of growth (ING) family that is a type II tumor suppressor gene including five members (ING1-5). As a tumor suppressor, ING4 inhibits tumor growth, invasion, and metastasis by multiple signaling pathways. In addition to that, ING4 can facilitate cancer cell sensitivity to chemotherapy and radiotherapy. Although ING4 loss is observed for many types of cancers, increasing evidences show that ING4 can be used for gene therapy. In this review, the recent progress of ING4 regulating tumorigenesis is discussed.