PPARgamma agonists sensitize PTEN-deficient resistant lung cancer cells to EGFR tyrosine kinase inhibitors by inducing autophagy

Roles of the peroxisome proliferator-activated receptors (PPARs) in the pathogenesis of hepatocellular carcinoma (HCC)

Hepatocellular carcinoma (HCC) holds a prominent position among global cancer types. Classically, HCC manifests in individuals with a genetic predisposition when they encounter risk elements, particularly in the context of liver cirrhosis. Peroxisome proliferator-activated receptors (PPARs), which are transcription factors activated by fatty acids, belong to the nuclear hormone receptor superfamily and play a pivotal role in the regulation of energy homeostasis. At present, three distinct subtypes of PPARs have been recognized: PPARα, PPARγ, and PPARβ/δ. They regulate the transcription of genes responsible for cellular development, energy metabolism, inflammation, and differentiation. In recent years, with the rising incidence of HCC, there has been an increasing focus on the mechanisms and roles of PPARs in HCC. PPARα primarily mediates the occurrence and development of HCC by regulating glucose and lipid metabolism, inflammatory responses, and oxidative stress. PPARβ/δ is closely related to the self-renewal ability of liver cancer stem cells (LCSCs) and the formation of the tumor microenvironment. PPARγ not only influences tumor growth by regulating the glucose and lipid metabolism of HCC, but its agonists also have significant clinical significance for the treatment of HCC. Therefore, this review offers an exhaustive examination of the role of the three PPAR subtypes in HCC progression, focusing on their mediation of critical cellular processes such as glucose and lipid metabolism, inflammation, oxidative stress, and other pivotal signaling pathways. At the end of the review, we discuss the merits and drawbacks of existing PPAR-targeted therapeutic strategies and suggest a few alternative combinatorial therapeutic approaches that diverge from conventional methods.

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.

Potential molecular biomarkers for the diagnosis and prognosis of bladder cancer

Bladder cancer (BC) is a common malignant tumor of urinary system, which can be divided into muscle-invasive BC (MIBC) and nonmuscle-invasive BC (NMIBC). The number of BC patients has been gradually increasing currently. At present, bladder tumours are diagnosed and followed-up using a combination of cystoscopic examination, cytology and histology. However, the detection of early grade tumors, which is much easier to treat effectively than advanced stage disease, is still insufficient. It frequently recurs and can progress when not expeditiously diagnosed and monitored following initial therapy for NMIBC. Treatment strategies are totally different for different stage diseases. Therefore, it is of great practical significance to study new biomarkers for diagnosis and prognosis. In this review, we summarize the current state of biomarker development in BC diagnosis and prognosis prediction. We retrospectively analyse eight diagnostic biomarkers and eight prognostic biomarkers, in which CK, P53, PPARγ, PTEN and ncRNA are emphasized for discussion. Eight molecular subtype systems are also identified. Clinical translation of biomarkers for diagnosis, prognosis, monitoring and treatment will hopefully improve outcomes for patients. These potential biomarkers provide an opportunity to diagnose tumors earlier and with greater accuracy, and help identify those patients most at risk of disease recurrence.

PPARγ Modulators in Lung Cancer: Molecular Mechanisms, Clinical Prospects, and Challenges

Lung cancer is one of the most lethal malignancies worldwide. Peroxisome proliferator-activated receptor gamma (PPARγ, NR1C3) is a ligand-activated transcriptional factor that governs the expression of genes involved in glucolipid metabolism, energy homeostasis, cell differentiation, and inflammation. Multiple studies have demonstrated that PPARγ activation exerts anti-tumor effects in lung cancer through regulation of lipid metabolism, induction of apoptosis, and cell cycle arrest, as well as inhibition of invasion and migration. Interestingly, PPARγ activation may have pro-tumor effects on cells of the tumor microenvironment, especially myeloid cells. Recent clinical data has substantiated the potential of PPARγ agonists as therapeutic agents for lung cancer. Additionally, PPARγ agonists also show synergistic effects with traditional chemotherapy and radiotherapy. However, the clinical application of PPARγ agonists remains limited due to the presence of adverse side effects. Thus, further research and clinical trials are necessary to comprehensively explore the actions of PPARγ in both tumor and stromal cells and to evaluate the in vivo toxicity. This review aims to consolidate the molecular mechanism of PPARγ modulators and to discuss their clinical prospects and challenges in tackling lung cancer.

20 years since the approval of first EGFR-TKI, gefitinib: Insight and foresight

Epidermal growth factor receptor (EGFR) actively involves in modulation of various cancer progression related mechanisms including angiogenesis, differentiation and migration. Therefore, targeting EGFR has surfaced as a prominent approach for the treatment of several types of cancers, including non-small cell lung cancer (NSCLC), pancreatic cancer, glioblastoma. Various first, second and third generation of EGFR tyrosine kinase inhibitors (EGFR-TKIs) have demonstrated effectiveness as an anti-cancer therapeutics. However, rapid development of drug resistance and mutations still remains a major challenge for the EGFR-TKIs therapy. Overcoming from intrinsic and acquired resistance caused by EGFR mutations warrants the further exploration of alternative strategies and discovery of novel inhibitors. In this review, we delve into the breakthrough discoveries have been made in previous 20 years, and discuss the currently ongoing efforts aimed to circumvent the chemo-resistance. We also highlight the new challenges, limitations and future directions for the development of improved therapeutic approaches such as fourth-generation EGFR-TKIs, peptides, nanobodies, PROTACs etc.

PPARγ agonist inhibits c-Myc-mediated colorectal cancer tumor immune escape

As a master transcription factor, c-Myc plays an important role in promoting tumor immune escape. In addition, PPARγ (peroxisome proliferator-activated receptor γ) regulates cell metabolism, inflammation, and tumor progression, while the effect of PPARγ on c-Myc-mediated tumor immune escape is still unclear. Here we found that cells treated with PPARγ agonist pioglitazone (PIOG) reduced c-Myc protein expression in a PPARγ-dependent manner. qPCR analysis showed that PIOG had no significant effect on c-Myc gene levels. Further analysis showed that PIOG decreased c-Myc protein half-life. Moreover, PIOG increased the binding of c-Myc to PPARγ, and induced c-Myc ubiquitination and degradation. Importantly, c-Myc increased PD-L1 and CD47 immune checkpoint protein expression and promoted tumor immune escape, while PIOG inhibited this event. These findings suggest that PPARγ agonist inhibited c-Myc-mediated tumor immune escape by inducing its ubiquitination and degradation.

Repurposing of Chronically Used Drugs in Cancer Therapy: A Chance to Grasp

Despite the advancement in drug discovery for cancer therapy, drug repurposing remains an exceptional opportunistic strategy. This approach offers many advantages (faster, safer, and cheaper drugs) typically needed to overcome increased challenges, i.e., side effects, resistance, and costs associated with cancer therapy. However, not all drug classes suit a patient's condition or long-time use. For that, repurposing chronically used medications is more appealing. This review highlights the importance of repurposing anti-diabetic and anti-hypertensive drugs in the global fight against human malignancies. Extensive searches of all available evidence (up to 30 March 2023) on the anti-cancer activities of anti-diabetic and anti-hypertensive agents are obtained from multiple resources (PubMed, Google Scholar, ClinicalTrials.gov, Drug Bank database, ReDo database, and the National Institutes of Health). Interestingly, more than 92 clinical trials are evaluating the anti-cancer activity of 14 anti-diabetic and anti-hypertensive drugs against more than 15 cancer types. Moreover, some of these agents have reached Phase IV evaluations, suggesting promising official release as anti-cancer medications. This comprehensive review provides current updates on different anti-diabetic and anti-hypertensive classes possessing anti-cancer activities with the available evidence about their mechanism(s) and stage of development and evaluation. Hence, it serves researchers and clinicians interested in anti-cancer drug discovery and cancer management.

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.

PPARγ inhibited tumor immune escape by inducing PD-L1 autophagic degradation

Blockade of the programmed death 1 (PD-1)/ programmed death ligand 1 (PD-L1) immune checkpoint could increase antitumor immunotherapy for multiple types of cancer, but the response rate of patients is about 10%-40%. Peroxisome proliferator activated receptor γ (PPARγ) plays an important role in regulating cell metabolism, inflammation, immunity, and cancer progression, while the mechanism of PPARγ on cancer cell immune escape is still unclear. Here we found that PPARγ expression exhibits a positive correlation with activation of T cells in non-small-cell lung cancer (NSCLC) by clinical analysis. Deficiency of PPARγ promoted immune escape of NSCLC by inhibiting T-cell activity, which was associated with increased PD-L1 protein level. Further analysis showed that PPARγ reduced PD-L1 expression independent of its transcriptional activity. PPARγ contains the microtubule-associated protein 1A/1B-light chain 3 (LC3) interacting region motif, which acts as an autophagy receptor for PPARγ binding to LC3, leading to degradation of PD-L1 in lysosomes, which in turn suppresses NSCLC tumor growth by increasing T-cell activity. These findings suggest that PPARγ inhibits the tumor immune escape of NSCLC by inducing PD-L1 autophagic degradation.

Regulation of Autophagy via Carbohydrate and Lipid Metabolism in Cancer

Metabolic changes are an important component of tumor cell progression. Tumor cells adapt to environmental stresses via changes to carbohydrate and lipid metabolism. Autophagy, a physiological process in mammalian cells that digests damaged organelles and misfolded proteins via lysosomal degradation, is closely associated with metabolism in mammalian cells, acting as a meter of cellular ATP levels. In this review, we discuss the changes in glycolytic and lipid biosynthetic pathways in mammalian cells and their impact on carcinogenesis via the autophagy pathway. In addition, we discuss the impact of these metabolic pathways on autophagy in lung cancer.

Altered expression of ACOX2 in non-small cell lung cancer

Peroxisomes are organelles that play essential roles in many metabolic processes, but also play roles in innate immunity, signal transduction, aging and cancer. One of the main functions of peroxisomes is the processing of very-long chain fatty acids into metabolites that can be directed to the mitochondria. One key family of enzymes in this process are the peroxisomal acyl-CoA oxidases (ACOX1, ACOX2 and ACOX3), the expression of which has been shown to be dysregulated in some cancers. Very little is however known about the expression of this family of oxidases in non-small cell lung cancer (NSCLC). ACOX2 has however been suggested to be elevated at the mRNA level in over 10% of NSCLC, and in the present study using both standard and bioinformatics approaches we show that expression of ACOX2 is significantly altered in NSCLC. ACOX2 mRNA expression is linked to a number of mutated genes, and associations between ACOX2 expression and tumour mutational burden and immune cell infiltration were explored. Links between ACOX2 expression and candidate therapies for oncogenic driver mutations such as KRAS were also identified. Furthermore, levels of acyl-CoA oxidases and other associated peroxisomal genes were explored to identify further links between the peroxisomal pathway and NSCLC. The results of this biomarker driven study suggest that ACOX2 may have potential clinical utility in the diagnosis, prognosis and stratification of patients into various therapeutically targetable options.

Peroxisome Proliferator-Activated Receptors and the Hallmarks of Cancer

Peroxisome proliferator-activated receptors (PPARs) function as nuclear transcription factors upon the binding of physiological or pharmacological ligands and heterodimerization with retinoic X receptors. Physiological ligands include fatty acids and fatty-acid-derived compounds with low specificity for the different PPAR subtypes (alpha, beta/delta, and gamma). For each of the PPAR subtypes, specific pharmacological agonists and antagonists, as well as pan-agonists, are available. In agreement with their natural ligands, PPARs are mainly focused on as targets for the treatment of metabolic syndrome and its associated complications. Nevertheless, many publications are available that implicate PPARs in malignancies. In several instances, they are controversial for very similar models. Thus, to better predict the potential use of PPAR modulators for personalized medicine in therapies against malignancies, it seems necessary and timely to review the three PPARs in relation to the didactic concept of cancer hallmark capabilities. We previously described the functions of PPAR beta/delta with respect to the cancer hallmarks and reviewed the implications of all PPARs in angiogenesis. Thus, the current review updates our knowledge on PPAR beta and the hallmarks of cancer and extends the concept to PPAR alpha and PPAR gamma.

Development of Dual Inhibitors Targeting Epidermal Growth Factor Receptor in Cancer Therapy

Epidermal growth factor receptor (EGFR) is of great significance in mediating cell signaling transduction and tumor behaviors. Currently, third-generation inhibitors of EGFR, especially osimertinib, are at the clinical frontier for the treatment of EGFR-mutant non-small-cell lung cancer (NSCLC). Regrettably, the rapidly developing drug resistance caused by EGFR mutations and the compensatory mechanism have largely limited their clinical efficacy. Given the synergistic effect between EGFR and other compensatory targets during tumorigenesis and tumor development, EGFR dual-target inhibitors are promising for their reduced risk of drug resistance, higher efficacy, lower dosage, and fewer adverse events than those of single-target inhibitors. Hence, we present the synergistic mechanism underlying the role of EGFR dual-target inhibitors against drug resistance, their structure-activity relationships, and their therapeutic potential. Most importantly, we emphasize the optimal target combinations and design strategies for EGFR dual-target inhibitors and provide some perspectives on new challenges and future directions in this field.

Telmisartan anti‐cancer activities mechanism through targeting N‐cadherin by mimicking ADH‐1 function

This study aimed to investigate if Telmisartan as a novel N‐cadherin antagonist, can overcome cell migration of cancer cells. We investigated the mechanism and influence of Docetaxel and Telmisartan (as an analogous to ADH‐1, which is a well‐known N‐cadherin antagonist) on cancer cells. The effect of ADH‐1 and Telmisartan on cell attachment in PC3, DU145, MDA‐MB‐468 cell lines using recombinant human N‐cadherin was studied. Cell viability assay was performed to examine the anti‐proliferative effects of Telmisartan, ADH‐1 and Docetaxel. Migration was examined via wound healing assay, and apoptosis was determined by flow cytometry. The expression of AKT‐1 as a downstream gene of N‐cadherin signalling pathway was assayed by real‐time PCR. Treatment of PC3, MDA‐MB‐468 and DU145 cells with Telmisartan (0.1 µM) and ADH‐1 (40 µM) resulted in 50%, 58% and approximately 20% reduction in cell attachment to N‐cadherin coated plate respectively. It shows reduction of cell attachment in PC3 and MDA‐MB‐468 cell lines appeared to be more sensitive than that of DU145 cells to the Telmisartan and ADH‐1 treatments. Telmisartan (0.1 µM) and Docetaxel (0.01 nM) significantly reduced cell migration in PC3 and MDA‐MB‐468 cell lines compared with the control group. Using Real‐time PCR, we found that Telmisartan, Docetaxel and ADH‐1 had significant influence on the AKT‐1 mRNA level. The results of the current study for the first time suggest that, Telmisartan, exerts anti‐proliferation and anti‐migration effects by targeting antagonistically N‐cadherin. Also, these data suggest that Telmisartan as a less expensive alternative to ADH‐1 could potentiate Docetaxel anticancer effects.

Alteration of PPAR-GAMMA (PPARG; PPARγ) and PTEN gene expression in acute myeloid leukemia patients and the promising anticancer effects of PPARγ stimulation using pioglitazone on AML cells

Background

In the new era of tailored cancer treatment strategies, finding a molecule to regulate a wide range of intracellular functions is valuable. The unique property of nuclear receptor peroxisome proliferator‐activated receptor‐γ (PPARγ; PPARG) in transmitting the anti‐survival signals of the chemotherapeutic drugs has fired the enthusiasm into the application of this receptor in cancer treatment.

Objectives

We aimed to investigate the expression of PPARγ and one of its downstream targets PTEN in non‐M3 acute myeloid leukemia (AML) patients. We also investigated the therapeutic value of PPARγ stimulation using pioglitazone in the AML‐derived U937 cell line.

Methods

The blood samples from 30 patients diagnosed with non‐M3 AML as well as 10 healthy individuals were collected and the mRNA expression levels of PPARγ and PTEN were evaluated. Additionally, we used trypan blue assay, MTT assay, and flow cytometry analysis to evaluate the anti‐leukemic effects of pioglitazone on U937 cells.

Results

While PTEN was significantly downregulated in AML patients as compared to the control group, the expression of PPARγ was increased in the patients’ group. The expression level of PPARγ was also negatively correlated with PTEN; however, it was not statistically significant. Besides, PPARγ stimulation using pioglitazone reduced survival and proliferative capacity of U937 cells through inducing apoptosis and suppression of cell transition from the G1 phase of the cell cycle.

Conclusion

The results of the present study shed more light on the importance of PPARγ and its stimulation in the therapeutic strategies of AML.

Iterative Upgrading of Small Molecular Tyrosine Kinase Inhibitors for EGFR Mutation in NSCLC: Necessity and Perspective

Molecular targeted therapy has been reported to have fewer adverse effects, and offer a more convenient route of administration, compared with conventional chemotherapy. With the development of sequencing technology, and research on the molecular biology of lung cancer, especially whole-genome information on non-small cell lung cancer (NSCLC), various therapeutic targets have been unveiled. Among the NSCLC-driving gene mutations, epidermal growth factor receptor (EGFR) mutations are the most common, and approximately 10% of Caucasian, and more than 50% of Asian, NSCLC patients have been found to have sensitive EGFR mutations. A variety of targeted therapeutic agents for EGFR mutations have been approved for clinical applications, or are undergoing clinical trials around the world. This review focuses on: the indications of approved small molecular kinase inhibitors for EGFR mutation-positive NSCLC; the mechanisms of drug resistance and the corresponding therapeutic strategies; the principles of reasonable and precision molecular structure; and the drug development discoveries of next-generation inhibitors for EGFR.

Emerging Approaches to Overcome Acquired Drug Resistance Obstacles to Osimertinib in Non-Small-Cell Lung Cancer

The pyrimidine core-containing compound Osimertinib is the only epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) from the third generation that has been approved by the U.S. Food and Drug Administration to target threonine 790 methionine (T790M) resistance while sparing the wild-type epidermal growth factor receptor (WT EGFR). It is nearly 200-fold more selective toward the mutant EGFR as compared to the WT EGFR. A tertiary cystein 797 to serine 797 (C797S) mutation in the EGFR kinase domain has hampered Osimertinib treatment in patients with advanced EGFR-mutated non-small-cell lung cancer (NSCLC). This C797S mutation is presumed to induce a tertiary-acquired resistance to all current reversible and irreversible EGFR TKIs. This review summarizes the molecular mechanisms of resistance to Osimertinib as well as different strategies for overcoming the EGFR-dependent and EGFR-independent mechanisms of resistance, new challenges, and a future direction.

Hispidulin inhibits proliferation, migration, and invasion by promoting autophagy via regulation of PPARγ activation in prostate cancer cells and xenograft models

Prostate cancer (PCa) is one of the important factors of cancer deaths especially in the western countries. Hispidulin (4',5,7-trihydroxy-6-methoxyflavone) is a phenolic flavonoid compound proved to possess anticancer properties, but its effects on PCa are left to be released. The aims of this study were to investigate the effects and the relative mechanisms of Hispidulin on PCa development. Hispidulin administration inhibited proliferation, invasion, and migration, while accelerated apoptosis in Du145 and VCaP cells, which was accompanied by PPARγ activation and autophagy enhancement. The beneficial effects of Hispidulin could be diminished by PPARγ inhibition. Besides, Hispidulin administration suppressed PCa tumorigenicity in Xenograft models, indicating the anticancer properties in vivo. Therefore, our work revealed that the anticancer properties of Hispidulin might be conferred by its activation on PPARγ and autophagy.

Acquired resistance to third-generation EGFR-TKIs and emerging next-generation EGFR inhibitors

The discovery that mutations in the EGFR gene are detected in up to 50% of lung adenocarcinoma patients, along with the development of highly efficacious epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), has revolutionized the treatment of this frequently occurring lung malignancy. Indeed, the clinical success of these TKIs constitutes a critical milestone in targeted cancer therapy. Three generations of EGFR-TKIs are currently approved for the treatment of EGFR mutation-positive non-small cell lung cancer (NSCLC). The first-generation TKIs include erlotinib, gefitinib, lapatinib, and icotinib; the second-generation ErbB family blockers include afatinib, neratinib, and dacomitinib; whereas osimertinib, approved by the FDA on 2015, is a third-generation TKI targeting EGFR harboring specific mutations. Compared with the first- and second-generation TKIs, third-generation EGFR inhibitors display a significant advantage in terms of patient survival. For example, the median overall survival in NSCLC patients receiving osimertinib reached 38.6 months. Unfortunately, however, like other targeted therapies, new EGFR mutations, as well as additional drug-resistance mechanisms emerge rapidly after treatment, posing formidable obstacles to cancer therapeutics aimed at surmounting this chemoresistance. In this review, we summarize the molecular mechanisms underlying resistance to third-generation EGFR inhibitors and the ongoing efforts to address and overcome this chemoresistance. We also discuss the current status of fourth-generation EGFR inhibitors, which are of great value in overcoming resistance to EGFR inhibitors that appear to have greater therapeutic benefits in the clinic.

•

EGFR gene mutations are detected in about 50% of non-small cell lung cancer (NSCLC) patients worldwide

•

The three generations of EGFR tyrosine kinase inhibitors (TKIs) are critical milestones for NSCLC patients

•

Like other targeted therapies, new EGFR mutations and coupled drug resistances emerge rapidly after TKI treatment, posing formidable obstacles to cancer management

•

The investigational fourth-generation EGFR inhibitors are of great promise, through a number of novel mechanisms, in overcoming these resistances after third-generation TKI treatment, and will bring more benefits to NSCLC patients

The Emerging Role of COX-2, 15-LOX and PPARγ in Metabolic Diseases and Cancer: An Introduction to Novel Multi-target Directed Ligands (MTDLs)

Emerging evidence supports an intertwining framework for the involvement of different inflammatory pathways in a common pathological background for a number of disorders. Of importance are pathways involving arachidonic acid metabolism by cyclooxygenase-2 (COX-2) and 15-lipoxygenase (15-LOX). Both enzyme activities and their products are implicated in a range of pathophysiological processes encompassing metabolic impairment leading to adipose inflammation and the subsequent vascular and neurological disorders, in addition to various pro- and antitumorigenic effects. A further layer of complexity is encountered by the disparate, and often reciprocal, modulatory effect COX-2 and 15-LOX activities and metabolites exert on each other or on other cellular targets, the most prominent of which is peroxisome proliferator-activated receptor gamma (PPARγ). Thus, effective therapeutic intervention with such multifaceted disorders requires the simultaneous modulation of more than one target. Here, we describe the role of COX-2, 15-LOX, and PPARγ in cancer and complications of metabolic disorders, highlight the value of designing multi-target directed ligands (MTDLs) modifying their activity, and summarizing the available literature regarding the rationale and feasibility of design and synthesis of these ligands together with their known biological effects. We speculate on the potential impact of MTDLs in these disorders as well as emphasize the need for structured future effort to translate these early results facilitating the adoption of these, and similar, molecules in clinical research.

Pharmacologic activation of autophagy without direct mTOR inhibition as a therapeutic strategy for treating dry macular degeneration

Dry age-related macular degeneration (AMD) is marked by the accumulation of extracellular and intracellular lipid-rich deposits within and around the retinal pigment epithelium (RPE). Inducing autophagy, a conserved, intracellular degradative pathway, is a potential treatment strategy to prevent disease by clearing these deposits. However, mTOR inhibition, the major mechanism for inducing autophagy, disrupts core RPE functions. Here, we screened autophagy inducers that do not directly inhibit mTOR for their potential as an AMD therapeutic in primary human RPE culture. Only two out of more than thirty autophagy inducers tested reliably increased autophagy flux in RPE, emphasizing that autophagy induction mechanistically differs across distinct tissues. In contrast to mTOR inhibitors, these compounds preserved RPE health, and one inducer, the FDA-approved compound flubendazole (FLBZ), reduced the secretion of apolipoprotein that contributes to extracellular deposits termed drusen. Simultaneously, FLBZ increased production of the lipid-degradation product β-hydroxybutyrate, which is used by photoreceptor cells as an energy source. FLBZ also reduced the accumulation of intracellular deposits, termed lipofuscin, and alleviated lipofuscin-induced cellular senescence and tight-junction disruption. FLBZ triggered compaction of lipofuscin-like granules into a potentially less toxic form. Thus, induction of RPE autophagy without direct mTOR inhibition is a promising therapeutic approach for dry AMD.

Mechanisms of Fritillariae Thunbergii Flos in lung cancer treatment from a systems pharmacology perspective

ETHNOPHARMACOLOGICAL RELEVANCE

Fritillariae Thunbergii Flos (FTF) included in the Chinese Pharmacopoeia (1977 Edition) is a Chinese medicinal herb traditionally used to treat bronchitis. In recent years, it has been applied in the treatment of lung cancer. However, the molecular mechanism remains largely unknown.

METHODS

The screening of bioactive compounds, acquisition of drug targets, network construction, and experimental validation in vivo were combined to explored the mechanism of FTF in the treatment of lung carcinoma with regards to systems pharmacology.

RESULTS

The network Lung Cancer Pathway consisted of 114 nodes (44 compounds and 70 potential targets) and 361 edges, as well as modules that included inflammatory response, angiogenesis, negative regulation of the apoptotic process, and positive regulation of cell proliferation and migration. It was examined by conducting experiments that involved the administration of ethanol-based extracts of FTF in Lewis lung carcinoma mice. The extracts exerted excellent anti-lung cancer effects in vivo by significantly inhibiting tumor proliferation, thereby extending the survival period of tumor-bearing mice. Moreover, FTF induced the downregulation of PIK3CG, Bcl-2, eNOS, VEGF, p-STAT3, and STAT3 genes in tumor-bearing mice.

CONCLUSIONS

The findings of the present study verify the therapeutic effects and mechanism of FTF on lung cancer and provide a theoretical basis to support the comprehensive utilization of FTF resources.

Identification of common signatures in idiopathic pulmonary fibrosis and lung cancer using gene expression modeling

Background

Idiopathic pulmonary fibrosis (IPF) is associated with an increased risk for lung cancer, but the underlying mechanisms driving malignant transformation remain largely unknown. This study aimed to identify differentially expressed genes (DEGs) distinguishing IPF and lung cancer from healthy individuals and common genes driving the transformation from healthy to IPF and lung cancer.

Methods

The gene expression data for IPF and non-small cell lung cancer (NSCLC) were retrieved from the Gene Expression Omnibus (GEO) database. The DEG signatures were identified via unsupervised two-way clustering (TWC) analysis, supervised support vector machine analysis, dimensional reduction, and mutual exclusivity analysis. Gene enrichment and pathway analyses were performed to identify common signaling pathways. The most significant signature genes in common among IPF and lung cancer were further verified by immunohistochemistry.

Results

The gene expression data from GSE24206 and GSE18842 were merged into a super array dataset comprising 86 patients with lung disorders (17 IPF and 46 NSCLC) and 51 healthy controls and measuring 23,494 unique genes. Seventy-nine signature DEGs were found among IPF and NSCLC. The peroxisome proliferator-activated receptor (PPAR) signaling pathway was the most enriched pathway associated with lung disorders, and matrix metalloproteinase-1 (MMP-1) in this pathway was mutually exclusive with several genes in IPF and NSCLC. Subsequent immunohistochemical analysis verified enhanced MMP1 expression in NSCLC associated with IPF.

Conclusions

For the first time, we defined common signature genes for IPF and NSCLC. The mutually exclusive sets of genes were potential drivers for IPF and NSCLC.

The role and function of PPARγ in bladder cancer

Peroxisome proliferator-activated receptor gamma (PPARγ), a member of the nuclear receptor superfamily, participates in multiple physiological and pathological processes. Extensive studies have revealed the relationship between PPARγ and various tumors. However, the expression and function of PPARγ in bladder cancer seem to be controversial. It has been demonstrated that PPARγ affects the occurrence and progression of bladder cancer by regulating proliferation, apoptosis, metastasis, and reactive oxygen species (ROS) and lipid metabolism, probably through PPARγ-SIRT1 feedback loops, the PI3K-Akt signaling pathway, and the WNT/β-catenin signaling pathway. Considering the frequent relapses after chemotherapy, some researchers have focused on the relationship between PPARγ and chemotherapy sensitivity in bladder cancer. Moreover, the feasibility of PPARγ ligands as potential therapeutic targets for bladder cancer has been uncovered. Taken together, this review summarizes the relevant literature and our findings to explore the complicated role and function of PPARγ in bladder cancer.

Detection of Allosteric Effects of lncRNA Secondary Structures Altered by SNPs in Human Diseases

Recent studies have shown that structuralized long non-coding RNAs (lncRNAs) play important roles in genetic and epigenetic processes. The spatial structures of most lncRNAs can be altered by distinct in vivo and in vitro cellular environments, as well as by DNA structural variations, such as single-nucleotide polymorphisms (SNPs) and variants (SNVs). In the present study, we extended candidate SNPs that had linkage disequilibria with those significantly associated with lung diseases in genome-wide association studies in order to investigate potential disease mechanisms originating from SNP structural changes of host lncRNAs. Following accurate alignments, we recognized 115 ternary-relationship pairs among 41 SNPs, 10 lncRNA transcripts, and 1 type of lung disease (adenocarcinoma of the lung). Then, we evaluated the structural heterogeneity induced by SNP alleles by developing a local-RNA-structure alignment algorithm and employing randomized strategies to determine the significance of structural variation. We identified four ternary-relationship pairs that were significantly associated with SNP-induced lncRNA allosteric effects. Moreover, these conformational changes disrupted the interactive regions and binding affinities of lncRNA-HCG23 and TF-E2F6, suggesting that these may represent regulatory mechanisms in lung diseases. Taken together, our findings support that SNP-induced changes in lncRNA conformations regulate many biological processes, providing novel insight into the role of the lncRNA “structurome” in human diseases.

Identification and development of non-cytotoxic cell death modulators: Impact of sartans and derivatives on PPARγ activation and on growth of imatinib-resistant chronic myelogenous leukemia cells

4'-((2-Propyl-1H-benzo[d]imidazol-1-yl)methyl)-[1,1'-biphenyl]-2-carboxylic acid derived from telmisartan was identified as lead for the design of cell death modulators. In this study, we evaluated the efficacy of telmisartan itself and other sartans in combination with imatinib against K562-resistant cells. The findings were directly used to further optimize the lead structure. Telmisartan and candesartan cilexetil represented the most effective sartans, thus the influence of carboxyl/methyl carboxylate groups at positions 7 (compounds 6, 7) or 4 (compounds 12-14) at the benzimidazole core was studied. Additionally, according to the results of a former structure-activity study, telmisartan was transformed to the related amide (1). Telmisartan amide 1, as well as the esters 6 and 12 markedly sensitized the resistant CML cells to imatinib treatment. Correlation with their potency to activate PPARγ is not given. Candesartan cilexetil, telmisartan and 1 showed the profile of partial agonists at PPARγ with EC₅₀ values of 4.2, 4.3 and 9.1 μM, respectively, while 6 and 12 caused only marginal intrinsic activation at 10 μM (A_max = 22% and 13%). However, the repression of the STAT5 phosphorylation relates with the possibility to sensitize K562-resistant CML cells to imatinib treatment. It is worth mentioning that all compounds were per se non-cytotoxic at relevant concentrations.

Anakoinosis: Correcting Aberrant Homeostasis of Cancer Tissue-Going Beyond Apoptosis Induction

The current approach to systemic therapy for metastatic cancer is aimed predominantly at inducing apoptosis of cancer cells by blocking tumor-promoting signaling pathways or by eradicating cell compartments within the tumor. In contrast, a systems view of therapy primarily considers the communication protocols that exist at multiple levels within the tumor complex, and the role of key regulators of such systems. Such regulators may have far-reaching influence on tumor response to therapy and therefore patient survival. This implies that neoplasia may be considered as a cell non-autonomous disease. The multi-scale activity ranges from intra-tumor cell compartments, to the tumor, to the tumor-harboring organ to the organism. In contrast to molecularly targeted therapies, a systems approach that identifies the complex communications networks driving tumor growth offers the prospect of disrupting or "normalizing" such aberrant communicative behaviors and therefore attenuating tumor growth. Communicative reprogramming, a treatment strategy referred to as anakoinosis, requires novel therapeutic instruments, so-called master modifiers to deliver concerted tumor growth-attenuating action. The diversity of biological outcomes following pro-anakoinotic tumor therapy, such as differentiation, trans-differentiation, control of tumor-associated inflammation, etc. demonstrates that long-term tumor control may occur in multiple forms, inducing even continuous complete remission. Accordingly, pro-anakoinotic therapies dramatically extend the repertoire for achieving tumor control and may activate apoptosis pathways for controlling resistant metastatic tumor disease and hematologic neoplasia.

Overcoming imatinib resistance in chronic myelogenous leukemia cells using non-cytotoxic cell death modulators

Recent studies examined the possibility to overcome imatinib resistance in chronic myeloid leukemia (CML) patients by combination therapy with peroxisome proliferator-activated receptor gamma (PPARγ) ligands. Pioglitazone, a full PPARγ agonist, improved the survival of patients by the gradual elimination of the residual CML stem cell pool. To evaluate the importance of the pharmacological profile of PPARγ agonists on the ability to circumvent resistance, the partial PPARγ agonist 4'-((2-propyl-1H-benzo[d]imidazol-1-yl)methyl)-[1,1'-biphenyl]-2-carboxylic acid, derived from telmisartan, and other related derivatives were investigated. The 4-substituted benzimidazole derivatives bearing a [1,1'-biphenyl]-2-carboxamide moiety sensitized K562-resistant cells to imatinib treatment. Especially the derivatives 18a-f, which did not activate PPARγ to more than 40% at 10 μM, retrieved the cytotoxicity of imatinib in these cells. The cell death modulating properties were higher than that of pioglitazone. It is of interest to note that all novel compounds were not cytotoxic neither on non-resistant nor on resistant cells. They exerted antitumor potency only in combination with imatinib.

PTEN in Lung Cancer: Dealing with the Problem, Building on New Knowledge and Turning the Game Around

Lung cancer is the most common malignancy and cause of cancer deaths worldwide, owing to the dismal prognosis for most affected patients. Phosphatase and tensin homolog deleted in chromosome 10 (PTEN) acts as a powerful tumor suppressor gene and even partial reduction of its levels increases cancer susceptibility. While the most validated anti-oncogenic duty of PTEN is the negative regulation of the PI3K/mTOR/Akt oncogenic signaling pathway, further tumor suppressor functions, such as chromosomal integrity and DNA repair have been reported. PTEN protein loss is a frequent event in lung cancer, but genetic alterations are not equally detected. It has been demonstrated that its expression is regulated at multiple genetic and epigenetic levels and deeper delineation of these mechanisms might provide fertile ground for upgrading lung cancer therapeutics. Today, PTEN expression is usually determined by immunohistochemistry and low protein levels have been associated with decreased survival in lung cancer. Moreover, available data involve PTEN mutations and loss of activity with resistance to targeted treatments and immunotherapy. This review discusses the current knowledge about PTEN status in lung cancer, highlighting the prevalence of its alterations in the disease, the regulatory mechanisms and the implications of PTEN on available treatment options.

[Role of PPAR-γ-regulated autophagy in genistein-induced inhibition of hepatic stellate cell activation]

OBJECTIVE

To investigate the inhibitory effect of genistein on activation of hepatic stellate cells (HSCs) in vitro and the role of the autophagy pathway regulated by PPAR-γ in mediating this effect.

METHODS

Cultured HSC-T6 cells were exposed to different concentrations of genistein for 48 h, and HSC activation was verified by detecting the expressions of -SMA and 1(I) collagen; autophagy activation in the cells was determined by detecting the expressions of LC3-II and p62 using Western blotting. The autophagy inhibitor 3-MA was used to confirm the role of autophagy in genistein-induced inhibition of HSC activation. A PPAR-γ inhibitor was used to explore the role of PPAR-γ in activating autophagy in the HSCs.

RESULTS

Genistein at concentrations of 5 and 50 μmol/L significantly inhibited the expressions of -SMA and 1(I) collagen (P < 0.05), markedly upregulated the expressions of PPAR-γ and the autophagy-related protein LC3-II (P < 0.05) and significantly down-regulated the expression of the ubiqutin-binding protein p62 (P < 0.05) in HSC-T6 cells. The cells pretreated with 3-MA prior to genistein treatment showed significantly increased protein expressions of -SMA and 1(I) collagen compared with the cells treated with genistein only (P < 0.05). Treatment with the PPAR-γ inhibitor obviously lowered the expression of LC3-II and enhanced the expression p62 in genistein-treated HSC-T6 cells, suggesting the activation of the autophagy pathway.

CONCLUSIONS

PPAR-γ- regulated autophagy plays an important role in mediating genistein-induced inhibition of HSC activation in vitro.

PPARγ activation serves as therapeutic strategy against bladder cancer via inhibiting PI3K-Akt signaling pathway

Background

Heterogeneity in bladder cancer results in variable clinical outcomes, posing challenges for clinical management of this malignancy. Recent studies suggest both tumor suppressive and oncogenic role of PPARγ in bladder cancer. The fuction of PPARγ signaling pathway in modulating carcinogenesis is controversial.

Methods

The expression of PPARγ and association with overall survival were analyzed in patients from two cohorts. The effect of PPARγ activation on cell proliferation, cell cycle, and cell apoptosis were determined with the agonists (rosiglitazone and pioglitazone), the inverse agonist (T0070907), and the antagonist (GW9662) in Umuc-3 and 5637 bladder cancer cells. The correlation of PPARγ activation with PI3K-Akt pathway was evaluated with RNA sequencing data from the TCGA cases and 30 human bladder cancer cell lines. The effect of PPARγ activation on tumor growth was validated with subcutaneous tumor models in vivo. The effect of PPARγ activation on PI3K-Akt signaling transduction was determined with multiple assays including immunohistochemistry, flow cytometry, proteomic array, and western blotting.

Results

We showed that PPARγ was a favorable prognostic factor in patients with bladder cancer. PPARγ activation by rosiglitazone and pioglitazone markedly induced cell cycle G2 arrest and apoptosis in bladder cancer cells, which resulted in inhibition of cell proliferation in vitro and suppression of tumor growth in vivo. The underlying mechanism involved marked inhibition of PI3K-Akt pathway.

Conclusions

This study reported the tumor-suppressive effect of PPARγ agonists in bladder cancer, suggesting that transactivation of PPARγ could be served as a potential strategy for the chemoprevention and therapeutic treatment of bladder cancer.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5426-6) contains supplementary material, which is available to authorized users.

Mechanism of Resistance to Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitors and a Potential Treatment Strategy

Treatment with epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) improves the overall survival of patients with EGFR-mutated non-small-cell lung cancer (NSCLC). First-generation EGFR-TKIs (e.g., gefitinib and erlotinib) or second-generation EGFR-TKIs (e.g., afatinib and dacomitinib) are effective for the treatment of EGFR-mutated NSCLC, especially in patients with EGFR exon 19 deletions or an exon 21 L858R mutation. However, almost all cases experience disease recurrence after 1 to 2 years due to acquired resistance. The EGFR T790M mutation in exon 20 is the most frequent alteration associated with the development of acquired resistance. Osimertinib-a third-generation EGFR-TKI-targets the T790M mutation and has demonstrated high efficacy against EGFR-mutated lung cancer. However, the development of acquired resistance to third-generation EGFR-TKI, involving the cysteine residue at codon 797 mutation, has been observed. Other mechanisms of acquired resistance include the activation of alternative pathways or downstream targets and histological transformation (i.e., epithelial⁻mesenchymal transition or conversion to small-cell lung cancer). Furthermore, the development of primary resistance through overexpression of the hepatocyte growth factor and suppression of Bcl-2-like protein 11 expression may lead to problems. In this report, we review these mechanisms and discuss therapeutic strategies to overcome resistance to EGFR-TKIs.

Bona fide receptor for hepatitis B and D viral infections: Mechanism, research models and molecular drug targets

Hepatitis B infections have become a serious public health issue globally, and the current first-line antiviral treatment for this disease is not a true cure. Recently, sodium taurocholate cotransporting polypeptide (NTCP), a liver-specific bile acid transporter, was identified as a bona fide receptor for hepatitis B virus (HBV) and its satellite virus, hepatitis delta virus (HDV). Identification of the HBV receptor has led to the development of robust cell cultures and provides a potential target for new treatments. This review summarizes the process by which NTCP was discovered and describes its clinical significance as the receptor for HBV and HDV entry.