Roles of peroxisome proliferator-activated receptor-alpha and -gamma in the development of non-small cell lung cancer

Systematic screening of synthetic organochalcogen compounds with anticancer activity using human lung adenocarcinoma spheroids

Lung adenocarcinoma stands as a leading global cause of cancer-related fatalities, with current therapeutic approaches remaining unsatisfactory. Given the association between elevated oxidative markers and the aggressive nature of cancer cells (including multidrug resistance and metastatic potential) that can predict poor outcome of lung adenocarcinoma patients, any compounds that interfere with their aberrant redox biology should be rationally explored as innovative intervention strategies. This study was designed to screen potential anticancer activities within nine newly synthesized organochalcogen - compounds characterized by the presence of oxygen, sulfur, or selenium elements in their structure and exhibiting antioxidant activity - and systematically evaluated their performance against cisplatin, the cornerstone therapeutic agent for lung adenocarcinoma. Our methodology involved the establishment of optimal conditions for generating single tumor spheroids using A549 human lung adenocarcinoma cell line. The initiation interval for spheroid formation was determined to be four days in vitro (DIV), and these single spheroids demonstrated sustained growth over a period of 20 DIV. Toxic dose-response curves were subsequently performed for each compound after 24 and 48 h of incubation at the 12th DIV. Our findings reveal that at least two of the synthetic organochalcogen compounds exhibited noteworthy anticancer activity, surpassing cisplatin in key parameters such as lower LD (Lethal Dose) 50, larger drug activity area, and maximum amplitude of effect, and are promising drugs for futures studies in the treatment of lung adenocarcinomas. Physicochemical descriptors and prediction ADME (absorption, distribution, metabolism, and excretion) parameters of selected compounds were obtained using SwissADME computational tool; Molinspiration server was used to calculate a biological activity score, and possible molecule targets were evaluated by prediction with the SwissTargetPrediction server. This research not only sheds light on novel avenues for therapeutic exploration but also underscores the potential of synthetic organochalcogen compounds as agents with superior efficacy compared to established treatments.

Targeting CD36 determines nicotine derivative NNK-induced lung adenocarcinoma carcinogenesis

Smoking carcinogen nicotine-derived nitrosamine ketone (NNK) is the most potent contributor to lung adenocarcinoma (LUAD) development, but the mechanism has not been fully elucidated. Here, we reported that fatty acid translocase CD36 was significantly overexpressed in both human LUAD tissues and NNK-induced A/J mice LUAD tumors. The overexpressed CD36 was positively correlated with Src kinase activation, smoking status, metastasis, and worse overall survival of patients with smoking history. Upon NNK binding with α7 nicotinic acetylcholine receptor (α7nAChR), sarcolemmal CD36 was increased and it interacted with surface α7nAChR and cytosol Src simultaneously, which in turn activated Src and downstream pro-carcinogenic kinase ERK1/2 and Akt, and finally caused LUAD cells to form subcutaneous and pulmonary metastatic tumors. This process could be blocked by CD36 knockdown and CD36 irreversible inhibitor SSO. Furthermore, the effect of NNK was inhibited obviously in CD36-/- A/J mice. Thus, targeting CD36 may provide a breakthrough therapy of LUAD.

Trinity of inflammation, innate immune cells and cross-talk of signalling pathways in tumour microenvironment

Unresolved inflammation is a pathological consequence of persistent inflammatory stimulus and perturbation in regulatory mechanisms. It increases the risk of tumour development and orchestrates all stages of tumorigenesis in selected organs. In certain cancers, inflammatory processes create the appropriate conditions for neoplastic transformation. While in other types, oncogenic changes pave the way for an inflammatory microenvironment that leads to tumour development. Of interest, hallmarks of tumour-promoting and cancer-associated inflammation are striking similar, sharing a complex network of stromal (fibroblasts and vascular cells) and inflammatory immune cells that collectively form the tumour microenvironment (TME). The cross-talks of signalling pathways initially developed to support homeostasis, change their role, and promote atypical proliferation, survival, angiogenesis, and subversion of adaptive immunity in TME. These transcriptional and regulatory pathways invariably contribute to cancer-promoting inflammation in chronic inflammatory disorders and foster "smouldering" inflammation in the microenvironment of various tumour types. Besides identifying common target sites of numerous cancer types, signalling programs and their cross-talks governing immune cells' plasticity and functional diversity can be used to develop new fate-mapping and lineage-tracing mechanisms. Here, we review the vital molecular mechanisms and pathways that establish the connection between inflammation and tumour development, progression, and metastasis. We also discussed the cross-talks between signalling pathways and devised strategies focusing on these interaction mechanisms to harness synthetic lethal drug combinations for targeted cancer therapy.

Identification of the novel markers of PPAR signalling affecting immune microenvironment and immunotherapy response of lung adenocarcinoma patients

Peroxisome proliferator-activated receptors (PPARs) are essential for cellular physiological processes. However, there is less research on the PPAR-related genes in lung adenocarcinoma (LUAD). Open-access data were get from the cancer genome atlas (TCGA) and gene expression omnibus (GEO) databases. All the analysis were conducted in the R software based on different R packages. In this study, we gauged the PPAR score employing a set of 72 PPAR-associated genes and probed the biological impact of this score on lung adenocarcinoma (LUAD). Subsequently, we established a unique signature composed of eight PPAR-related genes (ANGPTL4, ACSL3, ADIPOQ, FABP1, SLC27A1, ACOX2, PPARD and OLR1) to forecast the prognosis of LUAD. The signature's effectiveness in predicting survival was validated through the receiver operating characteristic curve in the TCGA-LUAD cohort. As per the pathway enrichment analysis, several crucial oncogenic pathways and metabolic processes were enriched in high-risk individuals. Further, we observed that these high-risk patients exhibited heightened genomic instability. Additionally, compared to the low-risk cohort, high-risk patients demonstrated diminished immune components and function. Intriguingly, high-risk patients exhibited a potential heightened sensitivity to immunotherapy and certain drugs, including Gefitinib, Afatinib, Erlotinib, IAP_5620, Sapitinib, LCL161, Lapatinib and AZD3759. The prognosis model based on eight PPAR-related genes has satisfactory prognosis prediction efficiency. Meanwhile, our results can provide direction for future studies in the relevant aspects.

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.

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.

Targeting Nuclear Receptors in Lung Cancer—Novel Therapeutic Prospects

Lung cancer, the second most commonly diagnosed cancer, is the major cause of fatalities worldwide for both men and women, with an estimated 2.2 million new incidences and 1.8 million deaths, according to GLOBOCAN 2020. Although various risk factors for lung cancer pathogenesis have been reported, controlling smoking alone has a significant value as a preventive measure. In spite of decades of extensive research, mechanistic cues and targets need to be profoundly explored to develop potential diagnostics, treatments, and reliable therapies for this disease. Nuclear receptors (NRs) function as transcription factors that control diverse biological processes such as cell growth, differentiation, development, and metabolism. The aberrant expression of NRs has been involved in a variety of disorders, including cancer. Deregulation of distinct NRs in lung cancer has been associated with numerous events, including mutations, epigenetic modifications, and different signaling cascades. Substantial efforts have been made to develop several small molecules as agonists or antagonists directed to target specific NRs for inhibiting tumor cell growth, migration, and invasion and inducing apoptosis in lung cancer, which makes NRs promising candidates for reliable lung cancer therapeutics. The current work focuses on the importance of various NRs in the development and progression of lung cancer and highlights the different small molecules (e.g., agonist or antagonist) that influence NR expression, with the goal of establishing them as viable therapeutics to combat lung cancer.

Expressions of Nuclear Factor-kappa B and Peroxisome Proliferator-activated Receptor-Gamma Proportional with Clinical Staging of Nasopharyngeal Carcinoma

BACKGROUND: Nasopharyngeal carcinoma (NPC) is a malignancy induced by the mutation of the transcription factors nuclear factor-kappa B (NF-kB) and peroxisome proliferator-activated receptor-gamma (PPAR-gamma). There was no known of the study about the association and targeted therapy of NF-kB and PPAR-gamma-induced NPC. AIM: This study analyzed and compared the proportion of NF-kB and PPAR-gamma and its association with the clinical characteristic of various NPC patients. METHODS: This was a cross-sectional study and conducted in Adam Malik General Hospital. The samples were paraffin block tissue obtained from 58 NPC patients and underwent immunohistochemistry staining for NF-kB or PPAR-gamma overexpression in March–November 2018. Determination of overexpression was based on the immunoreactive score. The association of NF-kB or PPAR-gamma overexpression with the clinical characteristics of the patients was analyzed using Fisher’s exact test. RESULTS: This study showed a significant increase of NF-kB and PPAR-gamma (p < 0.05). Male was found common than women (3.46:1) with non-keratinizing squamous cell carcinoma as the most common form of NPC (75.9%) and the 41–60 years old is the most common age (56.9%). Overexpression of NF-kB and PPAR-gamma was found mostly in T3-T4 (66.0%; 69.6%), N+ (92.5%; 91.3%), and clinical Stage IV (67.9%; 73.9%), respectively. CONCLUSION: The number of samples overexpressed was proportional to the clinical stage of NPC. This study provides an insight into the relationship of NF-kB and PPAR-gamma to NPC, suggesting their role in the development of malignancy.

Fatty Acid Synthase: An Emerging Target in Cancer

In recent years, lipid metabolism has garnered significant attention as it provides the necessary building blocks required to sustain tumor growth and serves as an alternative fuel source for ATP generation. Fatty acid synthase (FASN) functions as a central regulator of lipid metabolism and plays a critical role in the growth and survival of tumors with lipogenic phenotypes. Accumulating evidence has shown that it is capable of rewiring tumor cells for greater energy flexibility to attain their high energy requirements. This multi-enzyme protein is capable of modulating the function of subcellular organelles for optimal function under different conditions. Apart from lipid metabolism, FASN has functional roles in other cellular processes such as glycolysis and amino acid metabolism. These pivotal roles of FASN in lipid metabolism make it an attractive target in the clinic with several new inhibitors currently being tested in early clinical trials. This article aims to present the current evidence on the emergence of FASN as a target in human malignancies.

Role of lycopene in smoke-promoted chronic obstructive pulmonary disease and lung carcinogenesis

Chronic obstructive pulmonary disease (COPD) and lung cancer are a major cause of morbidity and mortality worldwide, with cigarette smoking being the single most important risk factor for both. Emerging evidence indicates alterations in reverse cholesterol transport-mediated removal of excess cholesterol from lung, and intracellular cholesterol overload to be involved in smoke-promoted COPD and lung cancer development. Since there are currently few effective treatments for COPD and lung cancer, it is important to identify food-derived, biologically active compounds, which can protect against COPD and lung cancer development. High intake of the carotenoid lycopene, as one of phytochemicals, is associated with a decreased risk of chronic lung lesions. This review article summarizes and discusses epidemiologic evidence, in vitro and in vivo studies regarding the prevention of smoke-promoted COPD and lung carcinogenesis through dietary lycopene as an effective intervention strategy. We focus on the recent research implying that lycopene preventive effect is through targeting the main genes involved in reverse cholesterol transport. This review also indicates gaps in knowledge about the function of lycopene against COPD and lung cancer, offering directions for further research.

The influence of conjugated linoleic acid on the expression of peroxisome proliferator-activated receptor-γ and selected apoptotic genes in non-small cell lung cancer

In recent years, peroxisome proliferator-activated receptor-γ (PPARγ) has been intensively studied. Because its activation is often associated with changes in the expression level of various apoptotic genes, many studies have emphasized the role of PPARγ as an important anticancer agent. However, in different types of cancer, different genes are influenced by PPARγ action. Previous studies showed that conjugated linoleic acid (CLA) was able to induce apoptosis, upregulate PPARG gene expression and activate PPARγ protein in certain human cancer cell lines. Moreover, some PPARγ agonists inhibited the growth of human lung cancer cells through the induction of apoptosis. Nevertheless, the impact of CLA on PPARγ mRNA and protein levels in non-small cell lung cancer (NSCLC) cell lines has not been investigated thus far. Therefore, in our study, we analysed the influence of the c9,t11 linoleic acid isomer on the expression of PPARG and other genes involved in the apoptotic response (BCL-2, BAX, and CDKN1A) in two NSCLC cell lines of different histological origin (A549 and Calu-1) and in normal human bronchial epithelial Beas-2B cells. Cells were treated with several doses of c9,t11 CLA, followed by RNA and protein isolation, cDNA synthesis, real-time quantitative PCR (RT-qPCR) and Western blot analysis. We showed that the investigated CLA isomer was able to enhance the expression of PPARγ in the examined cell lines and alter the mRNA and protein levels of genes involved in apoptosis. Fluorescent staining and MMT assay revealed the antiproliferative potential of CLA as well as its ability to activate pathways that lead to cell death.

The permissive role of TCTP in PM2.5/NNK-induced epithelial-mesenchymal transition in lung cells

Background

Translationally controlled tumor protein (TCTP) is linked to lung cancer. However, upon lung cancer carcinogens stimulation, there were no reports on the relationship between TCTP and lung cell carcinogenic epithelial–mesenchymal transition (EMT). This study was designed to investigate the molecular mechanism of regulation of TCTP expression and its role in lung carcinogens-induced EMT.

Methods

To study the role of TCTP in lung carcinogens [particulate matter 2.5 (PM_2.5) or 4-methylnitrosamino-l-3-pyridyl-butanone (NNK)]-induced EMT, PM_2.5/NNK-treated lung epithelial and non-small cell lung cancer (NSCLC) cells were tested. Cell derived xenografts, human lung cancer samples and online survival analysis were used to confirm the results. MassArray assay, Real-time PCR and Reporter assays were performed to elucidate the mechanism of regulation of TCTP expression. All statistical analyses were performed using GraphPad Prism version 6.0 or SPSS version 20.0.

Results

Translationally controlled tumor protein and vimentin expression were up-regulated in PM_2.5/NNK-treated lung cells and orthotopic implantation tumors. TCTP expression was positively correlated with vimentin in human NSCLC samples. Patients with high expression of TCTP displayed reduced overall and disease-free survival. TCTP overexpression could increase vimentin expression and promote cell metastasis. Furthermore, PM_2.5/NNK stimulation brought a synergistic effect on EMT in TCTP-transfected cells. TCTP knockdown blocked PM_2.5/NNK carcinogenic effect. Mechanically, PM_2.5/NNK-induced TCTP expression was regulated by one microRNA, namely miR-125a-3p, but not by methylation on TCTP gene promoter. The level of TCTP was regulated by its specific microRNA during the process of PM_2.5/NNK stimulation, which in turn enhanced vimentin expression and played a permissive role in carcinogenic EMT.

Conclusions

Our results provided new insights into the mechanisms of TCTP regulatory expression in lung carcinogens-induced EMT. TCTP and miR-125a-3p might act as potential prognostic biomarkers and therapeutic targets for NSCLC.

Ambient fine particulate matter inhibits 15-lipoxygenases to promote lung carcinogenesis

Background

Epidemiological observations have demonstrated that ambient fine particulate matter with d_p < 2.5 μm (PM_2.5) as the major factor responsible for the increasing incidence of lung cancer in never-smokers. However, there are very limited experimental data to support the association of PM_2.5 with lung carcinogenesis and to compare PM_2.5 with smoking carcinogens.

Methods

To study whether PM_2.5 can contribute to lung tumorigenesis in a way similar to smoking carcinogen 4-methylnitrosamino-l-3-pyridyl-butanone (NNK) via 15-lipoxygenases (15-LOXs) reduction, normal lung epithelial cells and cancer cells were treated with NNK or PM_2.5 and then epigenetically and post-translationally examined the cellular and molecular profiles of the cells. The data were verified in lung cancer samples and a mouse lung tumor model.

Results

We found that similar to smoking carcinogen NNK, PM2.5 significantly enhanced cell proliferation, migration and invasion, but reduced the levels of 15-lipoxygenases-1 (15-LOX1) and 15-lipoxygenases-2 (15-LOX2), both of which were also obviously decreased in lung cancer tissues. 15-LOX1/15-LOX2 overexpression inhibited the oncogenic cell functions induced by PM2.5/NNK. The tumor formation and growth were significantly higher/faster in mice implanted with PM2.5- or NNK-treated NCI-H23 cells, accompanied with a reduction of 15-LOX1/15-LOX2. Moreover, 15-LOX1 expression was epigenetically regulated at methylation level by PM2.5/NNK, while both 15-LOX1 and 15-LOX2 could be significantly inhibited by a set of PM2.5/NNK-mediated microRNAs.

Conclusion

Collectively, PM2.5 can function as the smoking carcinogen NNK to induce lung tumorigenesis by inhibiting 15-LOX1/15-LOX2.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1380-z) contains supplementary material, which is available to authorized users.

Heterogeneity of PTEN and PPAR-γ in cancer and their prognostic application to bladder cancer

The aim of the present study was to determine the prognostic value of peroxisome proliferator-activated receptor-γ (PPAR-γ) and phosphatase and tensin homologue deleted on chromosome ten (PTEN) for bladder cancer. Data were collected from The Cancer Genome Atlas (TCGA), a public database, and were analyzed to assess PTEN and PPAR-γ heterogeneity as well as distinct trends in bladder cancers. Furthermore, PPAR-γ and PTEN expression levels and their association with one another were evaluated. Finally, the prognostic significance of PPAR-γ and PTEN for bladder cancer was validated in vivo using clinical samples. Based on the TCGA database, PTEN levels were significantly increased in bladder cancers (P<0.001); whereas PPAR-γ expression was downregulated in the same samples (P<0.05). Furthermore, linear correlation analysis indicated that in bladder cancers, PPAR-γ and PTEN are inversely correlated (P<0.001). The assessment and analysis of clinical samples revealed that PPAR-γ was significantly elevated in tumor tissues (P<0.001); however, PTEN was downregulated in cancer tissues (P<0.001). Furthermore, PPAR-γ expression determined by immunohistochemistry grey level (P=0.002) was also elevated in high-grade and invasive bladder cancers compared with low-grade and superficial tumors, whereas PTEN levels exhibited the opposite in this analysis (P=0.001). In individuals with lymphoid metastasis, PPAR-γ was significantly increased (P<0.001), and PTEN was significantly decreased (P<0.001). Pearson analysis revealed a significant negative correlation between PPAR-γ and PTEN expression (r=-0.604, P<0.05). In conclusion, tissue heterogeneity was observed with respect to PPAR-γ and PTEN expression in bladder cancer. PTEN and PPAR-γ expression are negatively correlated and may be excellent indicators of bladder cancer tumorigenesis and progression.

Ameliorating effect of lipo-ATRA treatment on the expression of TIG3 and its suppressing effect on PPARγ gene expression in lung cancer animal model

This study aimed to find out the molecular therapeutic effect of lipo-ATRA on tumour suppressor TIG3 and cell proliferative biomarker PPARγ in B (a) P-induced lung cancer model. In RT-PCR study, ATRA- and lipo-ATRA-treated mice samples showed relatively higher TIG3 expression and decreased PPARγ expression (Band density) than cancer control. Among treatments, lipo-ATRA showed vital effect than free ATRA by enhancing TIG3 and decreasing PPARγ. The qPCR results also showed significant (p ≤ 0.05) difference in both TIG3 and PPAR (RQ values of TIG3, lipo-ATRA 23.85 ± 1.29; free ATRA 10.43 ± 1.81 and for PPARγ, lipo-ATRA 4.707 ± 1.21; free ATRA 15.78 ± 2.34). From this, we conclude that liposomal ATRA formulation is most preferable for prolonged delivery of ATRA at targeted site to favour molecular action. It implies that the therapeutic effect of lipo-ATRA in lung cancer was exhibited by ameliorating the TIG3 expression and by suppressing the expression of PPARγ.

PPAR Agonists for the Prevention and Treatment of Lung Cancer

Lung cancer is the most common and most fatal of all malignancies worldwide. Furthermore, with more than half of all lung cancer patients presenting with distant metastases at the time of initial diagnosis, the overall prognosis for the disease is poor. There is thus a desperate need for new prevention and treatment strategies. Recently, a family of nuclear hormone receptors, the peroxisome proliferator-activated receptors (PPARs), has attracted significant attention for its role in various malignancies including lung cancer. Three PPARs, PPARα, PPARβ/δ, and PPARγ, display distinct biological activities and varied influences on lung cancer biology. PPARα activation generally inhibits tumorigenesis through its antiangiogenic and anti-inflammatory effects. Activated PPARγ is also antitumorigenic and antimetastatic, regulating several functions of cancer cells and controlling the tumor microenvironment. Unlike PPARα and PPARγ, whether PPARβ/δ activation is anti- or protumorigenic or even inconsequential currently remains an open question that requires additional investigation. This review of current literature emphasizes the multifaceted effects of PPAR agonists in lung cancer and discusses how they may be applied as novel therapeutic strategies for the disease.

Tolerogenic Dendritic Cells for Regulatory T Cell Induction in Man

Dendritic cells (DCs) are highly specialized professional antigen-presenting cells that regulate immune responses, maintaining the balance between tolerance and immunity. Mechanisms via which they can promote central and peripheral tolerance include clonal deletion, the inhibition of memory T cell responses, T cell anergy, and induction of regulatory T cells (Tregs). These properties have led to the analysis of human tolerogenic DCs as a therapeutic strategy for the induction or re-establishment of tolerance. In recent years, numerous protocols for the generation of human tolerogenic DCs have been developed and their tolerogenic mechanisms, including induction of Tregs, are relatively well understood. Phase I trials have been conducted in autoimmune disease, with results that emphasize the feasibility and safety of treatments with tolerogenic DCs. Therefore, the scientific rationale for the use of tolerogenic DCs therapy in the fields of transplantation medicine and allergic and autoimmune diseases is strong. This review will give an overview on efforts and protocols to generate human tolerogenic DCs with focus on IL-10-modulated DCs as inducers of Tregs and discuss their clinical applications and challenges faced in further developing this form of immunotherapy.

Estrogen receptor alpha promotes smoking-carcinogen-induced lung carcinogenesis via cytochrome P450 1B1

Smoking carcinogen N-nitrosamines such as 4-methylnitrosamino-l-3-pyridyl-butanone (NNK) require metabolic activation to exert their genotoxicity. The first activation step is mainly catalyzed by cytochrome P450 (CYP) family. Estrogen receptor α (ERα) plays a role in lung pathology. The association between them is unknown. In this study, we explored the relationship and function of CYP1B1 and ERα in NNK-induced lung tumorigenesis. CYP1B1 and ERα expression was analyzed in human lung cancer tissues and NNK-induced lung tumor of A/J mice. Cell lines NCI-H23 and NCI-H460 were employed to further study the responsible mechanisms using various cellular and molecular approaches. Our in vivo experiments demonstrated that CYP1B1 and ERα were over-expressed at the early stage of NNK-induced lung tumorigenesis. Microarray analysis found that ERα was involved in the extracellular-signal-regulated kinase (ERK)/MAPK pathway. NNK activated RAS/ERK/AP1 as it remarkably increased the levels of p-ERK, c-Fos, and c-Jun but inhibited multiple negative regulators of Ras/ERK/AP1, Pdcd4, Spry1, Spry2, and Btg2 through up-regulating miR-21. Both CYP1B1 siRNA and ERK-specific inhibitor U0126 suppressed NNK-mediated ERα up-regulation, suggesting that ERα was downstream of CYP1B1 and ERK. ERK inactivation led to the accumulation of CYP1B1, indicating that CYP1B1 was upstream of ERK activation. Inhibition of ERK or ERα decreased NNK-induced cell proliferation. Blockage of CYP1B1 or ERα induced apoptosis of lung cancer cells. Collectively, NNK-mediated ERα induction is via CYP1B1 and ERK and contributes to the lung carcinogenesis. The inhibition of CYP1B1, ERK, or ERα may arrest the lung cancer cell growth, implicating a pivotal strategy for the treatment of lung cancer.

KEY MESSAGES

Smoking carcinogen NNK requires metabolic activation to exert their genotoxicity. CYP1B1 is the enzyme to catalyze NNK. NNK activates CYP1B1 and ERK to induce ERα. Inhibition of CYP1B1, ERK, or ERα arrests the lung cancer cell growth.

Fenofibrate in cancer: mechanisms involved in anticancer activity

Objective: To review the mechanisms of anti-cancer activity of fenofibrate (FF) and other Peroxisome Proliferator Activator Receptor α (PPARα) agonists based on evidences reported in the published literature.Methods: We extensively reviewed the literature concerning FF as an off target anti-cancer drug. Controversies regarding conflicting findings were also addressed.Results: The main mechanism involved in anti-cancer activity is anti-angiogenesis through down-regulation of  Vascular Endothelial Growth Factor (VEGF), Vascular Endothelial Growth Factor Receptor (VEGFR) and Hypoxia Inducible factor-1 α (HIF-1α), inhibition of endothelial cell migration, up-regulation of endostatin and thrombospondin-1, but there are many other contributing mechanisms like apoptosis and cell cycle arrest, down-regulation of Nuclear Factor Kappa B (NF-kB) and Protein kinase B (Akt) and decrease of cellular energy by impairing mitochondrial function. Growth impairment is related to down-regulation of Phospho-Inositol 3 Kinase (PI3K)/Akt axis and down-regulation of the p38 map kinase (MAPK) cascade. A possible role should be assigned to FF stimulated over-expression of Tribbles Homolog-3 (TRIB3) which inhibits Akt phosphorylation. Important anti-cancer and anti-metastatic activities are due to down-regulation of MCP-1 (monocyte chemotactic protein-1), decreased Metalloprotease-9 (MMP-9) production, weak down-regulation of adhesion molecules like E selectin, intercellular adhesion molecules (ICAM) and Vascular Endothelial Adhesion Molecules (VCAM), and decreased secretion of chemokines like Interleukin-6 (IL-6), and down-regulation of cyclin D-1. There is no direct link between FF activity in lipid metabolism and anticancer activity, except for the fact that many anticancer actions are dependent from PPARα agonism. FF exhibits also PPARα independent anti-cancer activities.Conclusions: There are strong evidences indicating that FF can disrupt growth-related activities in many different cancers, due to anti-angiogenesis and anti-inflammatory effects. Therefore FF may be useful as a complementary adjunct treatment of cancer, particularly included in anti-angiogenic protocols like those currently increasingly used in glioblastoma. There are sound reasons to initiate well planned phase II clinical trials for FF as a complementary adjunct treatment of cancer.

Pioglitazone, a PPARγ agonist, inhibits growth and invasion of human hepatocellular carcinoma via blockade of the rage signaling

Pioglitazone (PGZ), a synthetic PPARγ ligand, is known to have anti-tumor activity. However, it is unclear how it acts against hepatocellular carcinoma (HCC). We hypothesized that the pathological receptor for advanced glycation end products (RAGE) is involved in the PGZ anti-tumor process. To test this notion, human primary HCC tissues and corresponding adjacent non-cancerous tissues (ANCT) from 75 consecutive cases were analyzed. The expression and clinical significance of RAGE was assessed by immunohistochemical assay through tissue microarray. After HCC cells were pretreated with different concentrations of PGZ, cell proliferation, apoptosis, cell invasion, and cell cycle distribution were evaluated by multiple assays. The results showed that, the positive expression of RAGE was significantly higher in HCC tissues than in ANCT (66.7% vs. 36.0%, P < 0.001), and was closely associated with pathological staging (P = 0.014) and lymph-vascular space invasion (P = 0.003). Moreover, PGZ inhibited proliferative activity and invasive potential, and induced apoptosis and cell cycle arrest in HCC cells resulting in increased expression of PPARγ and decreased expression of RAGE, NF-κB, HMGB1, p38MAPK, Ki-67, MMP-2, and CyclinD1. Furthermore, knockdown of RAGE or NF-κB by siRNA effectively suppressed cell proliferation and invasion, and mediated the inhibitory effects of PGZ in HCC cells. Taken together, our findings suggest that, RAGE is overexpressed in human HCC tissues, and is closely associated with the pathological staging and tumor invasion of HCC. In addition, PGZ as a PPARγ agonist may inhibit growth and invasion of HCC cells via blockade of the RAGE signaling.

[Screening and identification of novel drug-resistant genes in CD133+ and CD133- lung adenosarcoma cells using cDNA microarray]

背景与目的

肿瘤干细胞可能是肿瘤多药耐药的主要原因，CD133是目前较为公认的肿瘤干细胞标记物。本研究旨在应用功能分类基因芯片筛选CD133⁺和CD133^-肺腺癌细胞中差异表达的肿瘤耐药基因，寻求新的肺癌耐药相关基因。

方法

免疫磁珠分选法分选A549细胞，采用功能分类基因芯片筛选CD133⁺和CD133^-肺腺癌细胞中差异表达的肿瘤耐药基因，并使用RT-qPCR验证。顺铂半数有效抑制浓度（half inhibiting concentration, IC₅₀）、阿霉素IC₅₀作用A549细胞48 h后，RT-qPCR检测肿瘤耐药基因CYP2C19、CYP2D6、CYP2E1、GSK3α、PPARα和PPARβ/δ的表达变化。

结果

共筛查出31个差异表达的肿瘤耐药基因，与CD133^-细胞相比，CD133⁺细胞有30个基因表达上调，1个基因表达下调。RT-qPCR结果与芯片一致。A549细胞经1.97 μg/mL顺铂或0.61 μg/mL阿霉素作用48 h后，CYP2C19、CYP2D6、CYP2E1、GSK3α、PPARα和PPARβ/δ等肿瘤耐药基因表达上调。

结论

利用功能分类基因芯片筛选出31个可能与CD133⁺肺腺癌细胞耐药相关的基因，其中CYP2C19、CYP2D6、CYP2E1、GSK3α、PPARα和PPARβ/δ为新发现的肺癌耐药相关基因。

Loss of miR125a expression in a model of K-ras-dependent pulmonary premalignancy

Understanding the molecular pathogenesis of lung cancer is necessary to identify biomarkers/targets specific to individual airway molecular profiles and to identify options for targeted chemoprevention. Herein, we identify mechanisms by which loss of microRNA (miRNA)125a-3p (miR125a) contributes to the malignant potential of human bronchial epithelial cells (HBEC) harboring an activating point mutation of the K-ras proto-oncogene (HBEC K-ras). Among other miRNAs, we identified significant miR125a loss in HBEC K-ras lines and determined that miR125a is regulated by the PEA3 transcription factor. PEA3 is upregulated in HBEC K-ras cells, and genetic knockdown of PEA3 restores miR125a expression. From a panel of inflammatory/angiogenic factors, we identified increased CXCL1 and vascular endothelial growth factor (VEGF) production by HBEC K-ras cells and determined that miR125a overexpression significantly reduces K-ras-mediated production of these tumorigenic factors. miR125a overexpression also abrogates increased proliferation of HBEC K-ras cells and suppresses anchorage-independent growth (AIG) of HBEC K-ras/P53 cells, the latter of which is CXCL1-dependent. Finally, pioglitazone increases levels of miR125a in HBEC K-ras cells via PEA3 downregulation. In addition, pioglitazone and miR125a overexpression elicit similar phenotypic responses, including suppression of both proliferation and VEGF production. Our findings implicate miR125a loss in lung carcinogenesis and lay the groundwork for future studies to determine whether miR125a is a possible biomarker for lung carcinogenesis and/or a chemoprevention target. Moreover, our studies illustrate that pharmacologic augmentation of miR125a in K-ras-mutated pulmonary epithelium effectively abrogates several deleterious downstream events associated with the mutation.

The peroxisome proliferator-activated receptor (PPAR) α agonist fenofibrate suppresses chemically induced lung alveolar proliferative lesions in male obese hyperlipidemic mice

Activation of peroxisome proliferator-activated receptor (PPAR) α disrupts growth-related activities in a variety of human cancers. This study was designed to determine whether fenofibrate, a PPARα agonist, can suppress 4-nitroquinoline 1-oxide (4-NQO)-induced proliferative lesions in the lung of obese hyperlipidemic mice. Male Tsumura Suzuki Obese Diabetic mice were subcutaneously injected with 4-NQO to induce lung proliferative lesions, including adenocarcinomas. They were then fed a diet containing 0.01% or 0.05% fenofibrate for 29 weeks, starting 1 week after 4-NQO administration. At week 30, the incidence and multiplicity (number of lesions/mouse) of pulmonary proliferative lesions were lower in mice treated with 4-NQO and both doses of fenofibrate compared with those in mice treated with 4-NQO alone. The incidence and multiplicity of lesions were significantly lower in mice treated with 4-NQO and 0.05% fenofibrate compared with those in mice treated with 4-NQO alone (p<0.05). Both doses of fenofibrate significantly reduced the proliferative activity of the lesions in 4-NQO-treated mice (p<0.05). Fenofibrate also significantly reduced the serum insulin and insulin-like growth factor (IGF)-1 levels, and decreased the immunohistochemical expression of IGF-1 receptor (IGF-1R), phosphorylated Akt, and phosphorylated Erk1/2 in lung adenocarcinomas. Our results indicate that fenofibrate can prevent the development of 4-NQO-induced proliferative lesions in the lung by modulating the insulin-IGF axis.

Role of chronic obstructive pulmonary disease in lung cancer pathogenesis

Chronic obstructive pulmonary disease (COPD) and lung cancer are two important smoking related conditions. However, COPD has been shown to be an independent risk factor for lung cancer regardless of smoking history, suggesting that COPD and lung cancer may share a common pathogenesis. This review summarizes the epidemiology of lung cancer and COPD briefly, as well as discussing the potential for shared genetic risk, and shared genomic mechanisms, such as epigenetic changes or DNA damage induced by smoking. How key areas of COPD pathogenesis, such as inflammation, oxidative stress and protease imbalance may contribute to subsequent development of cancer will also be covered. Finally the possibility that consequences of COPD, such as hypoxia, influence carcinogenesis will be reviewed. By understanding the pathogenesis of COPD and lung cancer in detail it is possible that new treatments may be developed and the risk of lung cancer in COPD may be reduced.

Heterotrimeric G-protein, Gα16, is a critical downstream effector of non-canonical Wnt signaling and a potent inhibitor of transformed cell growth in non small cell lung cancer

G-protein-coupled receptors (GPCR) are the largest family of cell surface molecules that play important role/s in a number of biological and pathological processes including cancers. Earlier studies have highlighted the importance of Wnt7a signaling via its cognate receptor Frizzled9, a GPCR, in inhibition of cell proliferation, anchorage-independent growth, and reversal of transformed phenotype in non small cell lung cancer primarily through activation of the tumor suppressor, PPARγ. However, the G-protein effectors that couple to this important tumor suppressor pathway have not been identified, and are of potential therapeutic interest. In this study, by using two independent Wnt7a/Frizzled9-specific read-outs, we identify Gα16 as a novel downstream effector of Wnt7a/Frizzled9 signaling. Interestingly, Gα16 expression is severely down-regulated, both at the messenger RNA levels and protein levels, in many non small cell lung cancer cell lines. Additionally, through gene-specific knock-downs and expression of GTPase-deficient forms (Q212L) of Gα16, we also establish Gα16 as a novel regulator of non small cell lung cancer cell proliferation and anchorage-independent cell growth. Taken together, our data not only establish the importance of Gα16 as a critical downstream effector of the non-canonical Wnt signaling pathway but also as a potential therapeutic target for the treatment of non small cell lung cancer.

PPARγ-mediated and arachidonic acid-dependent signaling is involved in differentiation and lipid production of human sebocytes

The transcriptional basis of sebocyte differentiation and lipid production is mostly unclear. Peroxisome proliferator-activated receptor gamma (PPARγ), a lipid-activated transcription factor, has been implicated in differentiation and lipid metabolism of various cell types. Here, we show that PPARγ is differentially expressed in normal and pathological human sebocytes and appears to have roles in their differentiation and lipid production. We used laser-microdissected normal and pathological human sebaceous glands (SGs) and SZ95 cells (immortalized sebocyte cell line) analyzed by real-time quantitative PCR and immunohistochemistry. Lipids were analyzed by quantitative fluorimetry- and mass spectrometry-based approaches. We have observed that PPARγ and its target genes, ADRP (adipose differentiation-related protein) and PGAR (PPARγ angiopoietin-related protein), are expressed in sebocytes and show association with their level of differentiation. Also, PPARγ is present in normal and hyperplastic SG, whereas its expression levels are decreased in SG adenoma and SG carcinoma cells, reflecting a maturation-linked expression pattern. Furthermore, in SZ95 sebocytes, naturally occurring lipids, including arachidonic acid and arachidonic acid keto-metabolites (e.g., 5-KETE (5-oxo-6E,8Z,11Z,14Z-eicosatetraenoic acid), 12-KETE (12-oxo-5Z,8Z,10E,14Z-eicosatetraenoic acid)), appear to regulate PPARγ signaling pathways, which in turn modulate phospholipid biosynthesis and induce neutral lipid synthesis. Collectively, our findings highlight the importance of endogenous ligand-activated PPARγ signaling in human sebocyte biology and suggest that PPARγ might be a promising candidate for the clinical management of SG disorders.

New molecular insights in tobacco-induced lung cancer

We know that cigarette smoking is a leading preventable cause of carcinogenesis in lung cancer. Cigarette smoke is a mixture of more than 5000 chemical compounds, among which more than 60 are recognized to have a specific carcinogenic potential. Carcinogens and their metabolites (i.e., N-nitrosamines and polycyclic aromatic hydrocarbons) can activate multiple pathways, contributing to lung cell transformation in different ways. Nicotine, originally thought only to be responsible for tobacco addiction, is also involved in tumor promotion and progression with antiapoptotic and indirect mitogenic properties. Lung nodules are frequent in smokers and can be transformed into malignant tumors depending on persistant smoking status. Even if detailed mechanisms underlying tobacco-induced cancerogenesis are not completely elucitated, this report collects the emergent body of knowledge in order to simplify the extremely complex framework that links smoking exposure to lung cancer.

Association analyses identify multiple new lung cancer susceptibility loci and their interactions with smoking in the Chinese population

To find additional susceptibility loci for lung cancer, we tested promising associations from our previous genome-wide association study (GWAS) of lung cancer in the Chinese population in an extended validation sample size of 7,436 individuals with lung cancer (cases) and 7,483 controls. We found genome-wide significant (P < 5.0 × 10(-8)) evidence for three additional lung cancer susceptibility loci at 10p14 (rs1663689, close to GATA3, P = 2.84 × 10(-10)), 5q32 (rs2895680 in PPP2R2B-STK32A-DPYSL3, P = 6.60 × 10(-9)) and 20q13.2 (rs4809957 in CYP24A1, P = 1.20 × 10(-8)). We also found consistent associations for rs247008 at 5q31.1 (IL3-CSF2-P4HA2, P = 7.68 × 10(-8)) and rs9439519 at 1p36.32 (AJAP1-NPHP4, P = 3.65 × 10(-6)). Four of these loci showed evidence for interactions with smoking dose (P = 1.72 × 10(-10), P = 5.07 × 10(-3), P = 6.77 × 10(-3) and P = 4.49 × 10(-2) for rs2895680, rs4809957, rs247008 and rs9439519, respectively). These results advance our understanding of lung cancer susceptibility and highlight potential pathways that integrate genetic variants and smoking in the development of lung cancer.

Activation of PPARγ in myeloid cells promotes lung cancer progression and metastasis

Activation of peroxisome proliferator-activated receptor-γ (PPARγ) inhibits growth of cancer cells including non-small cell lung cancer (NSCLC). Clinically, use of thiazolidinediones, which are pharmacological activators of PPARγ is associated with a lower risk of developing lung cancer. However, the role of this pathway in lung cancer metastasis has not been examined well. The systemic effect of pioglitazone was examined in two models of lung cancer metastasis in immune-competent mice. In an orthotopic model, murine lung cancer cells implanted into the lungs of syngeneic mice metastasized to the liver and brain. As a second model, cancer cells injected subcutaneously metastasized to the lung. In both models systemic administration of pioglitazone increased the rate of metastasis. Examination of tissues from the orthotopic model demonstrated increased numbers of arginase I-positive macrophages in tumors from pioglitazone-treated animals. In co-culture experiments of cancer cells with bone marrow-derived macrophages, pioglitazone promoted arginase I expression in macrophages and this was dependent on the expression of PPARγ in the macrophages. To assess the contribution of PPARγ in macrophages to cancer progression, experiments were performed in bone marrow-transplanted animals receiving bone marrow from Lys-M-Cre+/PPARγ^flox/flox mice, in which PPARγ is deleted specifically in myeloid cells (PPARγ-Mac^neg), or control PPARγ^flox/flox mice. In both models, mice receiving PPARγ-Mac^neg bone marrow had a marked decrease in secondary tumors which was not significantly altered by treatment with pioglitazone. This was associated with decreased numbers of arginase I-positive cells in the lung. These data support a model in which activation of PPARγ may have opposing effects on tumor progression, with anti-tumorigenic effects on cancer cells, but pro-tumorigenic effects on cells of the microenvironment, specifically myeloid cells.

A Comparative Study of Mouse Hepatic and Intestinal Gene Expression Profiles under PPARα Knockout by Gene Set Enrichment Analysis

Gene expression profiling of PPARα has been used in several studies, but fewer studies went further to identify the tissue-specific pathways or genes involved in PPARα activation in genome-wide. Here, we employed and applied gene set enrichment analysis to two microarray datasets both PPARα related respectively in mouse liver and intestine. We suggested that the regulatory mechanism of PPARα activation by WY14643 in mouse small intestine is more complicated than in liver due to more involved pathways. Several pathways were cancer-related such as pancreatic cancer and small cell lung cancer, which indicated that PPARα may have an important role in prevention of cancer development. 12 PPARα dependent pathways and 4 PPARα independent pathways were identified highly common in both liver and intestine of mice. Most of them were metabolism related, such as fatty acid metabolism, tryptophan metabolism, pyruvate metabolism with regard to PPARα regulation but gluconeogenesis and propanoate metabolism independent of PPARα regulation. Keratan sulfate biosynthesis, the pathway of regulation of actin cytoskeleton, the pathways associated with prostate cancer and small cell lung cancer were not identified as hepatic PPARα independent but as WY14643 dependent ones in intestinal study. We also provided some novel hepatic tissue-specific marker genes.

HO-1 Induced by Cilostazol Protects Against TNF-α-associated Cytotoxicity via a PPAR-γ-dependent Pathway in Human Endothelial Cells

A large body of evidence has indicated that induction of endogenous antioxidative proteins seems to be a reasonable strategy for delaying the progression of cell injury. In our previous study, cilostazol was found to increase the expression of the antioxidant enzyme heme oxygenase-1 (HO-1) in synovial cells. Thus, the present study was undertaken to examine whether cilostazol is able to counteract tumor necrosis factor-α (TNF-α)-induced cell death in endothelial cells via the induction of HO-1 expression. We exposed human umbilical vein endothelial cells (HUVECs) to TNF-α (50 ng/ml), with or without cilostazol (10 µM). Pretreatment with cilostazol markedly reduced TNF-α-induced viability loss in the HUVECs, which was reversed by zinc protoporphyrine IX (ZnPP), an inhibitor of HO-1. Moreover, cilostazol increased HO-1 protein and mRNA expression. Cilostazol-induced HO-1 induction was markedly attenuated not only by ZnPP but also by copper-protoporphyrin IX (CuPP). In an assay measuring peroxisome proliferator-activated receptor-γ (PPAR-γ) transcription activity, cilostazol directly increased PPAR-γ transcriptional activity which was completely abolished by HO-1 inhibitor. Furthermore, increased PPAR-γ activity by cilostazol and rosiglitazone was completely abolished in cells transfected with HO-1 siRNA. Taken together, these results indicate that cilostazol up-regulates HO-1 and protects cells against TNF-α-induced endothelial cytotoxicity via a PPAR-γ-dependent pathway.

Chronic obstructive pulmonary disease and lung cancer: new molecular insights

Both chronic obstructive pulmonary disease (COPD) and lung cancer are major causes of death worldwide. In most cases this reflects cigarette smoke exposure which is able to induce an inflammatory response in the airways of smokers. Indeed, COPD is characterized by lower airway inflammation, and importantly, the presence of COPD is by far the greatest risk factor for lung cancer amongst smokers. Cigarette smoke induces the release of many inflammatory mediators and growth factors including TGF-β, EGFR, IL-1, IL-8 and G-CSF through oxidative stress pathways and this inflammation may persist for decades after smoking cessation. Mucus production is also increased by these inflammatory mediators, further linking airway inflammation to an important mechanism of lung cancer. A greater understanding of the molecular and cellular pathobiology that distinguishes smokers with lung cancer from smokers with and without COPD is needed to unravel the complex molecular interactions between COPD and lung cancer. By understanding the common signalling pathways involved in COPD and lung cancer the hope is that treatments will be developed that not only treat the underlying disease process in COPD, but also reduce the currently high risk of developing lung cancer in these patients.

Peroxisome proliferator-activated receptor gamma and early folliculogenesis during an acute hyperandrogenism condition

Acute hyperandrogenism decreases serum P levels and induces early apoptosis of antral follicles by a mechanism mediated by the peroxisome proliferator-activated receptor gamma system and independent of the steroidogenic acute regulator protein.

Cigarette smoking, cyclooxygenase-2 pathway and cancer

Cigarette smoking is a major cause of mortality and morbidity worldwide. Cyclooxygenase (COX) and its derived prostanoids, mainly including prostaglandin E2 (PGE2), thromboxane A2 (TxA2) and prostacyclin (PGI2), have well-known roles in cardiovascular disease and cancer, both of which are associated with cigarette smoking. This article is focused on the role of COX-2 pathway in smoke-related pathologies and cancer. Cigarette smoke exposure can induce COX-2 expression and activity, increase PGE2 and TxA2 release, and lead to an imbalance in PGI2 and TxA2 production in favor of the latter. It exerts pro-inflammatory effects in a PGE2-dependent manner, which contributes to carcinogenesis and tumor progression. TxA2 mediates other diverse biologic effects of cigarette smoking, such as platelet activation, cell contraction and angiogenesis, which may facilitate tumor growth and metastasis in smokers. Among cigarette smoke components, nicotine and its derived nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are the most potent carcinogens. COX-2 and PGE2 have been shown to play a pivotal role in many cancers associated with cigarette smoking, including cancers of lung, gastric and bladder, while the information for the role of TxA2 and PGI2 in smoke-associated cancers is limited. Recent findings from our group have revealed how NNK influences the TxA2 to promote the tumor growth. Better understanding in the above areas may help to generate new therapeutic protocols or to optimize the existing treatment strategy.

Anticancer actions of PPARγ ligands: Current state and future perspectives in human lung cancer

Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent nuclear transcription factors and members of the nuclear receptor superfamily. Of the three PPARs identified to date (PPARγ, PPARβ/δ, and PPARα), PPARγ has been studied the most, in part because of the availability of PPARγ agonists (also known as PPARγ ligands) and its significant effects on the management of several human diseases including type 2 diabetes, metabolic syndrome, cardiovascular disease and cancers. PPARγ is expressed in many tumors including lung cancer, and its function has been linked to the process of lung cancer development, progression and metastasis. Studies performed in gynogenic and xenograft models of lung cancer showed decreased tumor growth and metastasis in animals treated with PPARγ ligands. Furthermore, data are emerging from retrospective clinical studies that suggest a protective role for PPARγ ligands on the incidence of lung cancer. This review summarizes the research being conducted in this area and focuses on the mechanisms and potential therapeutic effects of PPARγ ligands as a novel anti-lung cancer treatment strategy.