Rosiglitazone prevents the progression of preinvasive lung cancer in a murine model

Repurposing drugs targeting metabolic diseases for cancer therapeutics

Hurdles in the identification of new drugs for cancer treatment have made drug repurposing an increasingly appealing alternative. The approach involves the use of old drugs for new therapeutic purposes. It is cost-effective and facilitates rapid clinical translation. Given that cancer is also considered a metabolic disease, drugs for metabolic disorders are being actively repurposed for cancer therapeutics. In this review, we discuss the repurposing of such drugs approved for two major metabolic diseases, diabetes and cardiovascular disease (CVD), which have shown potential as anti-cancer treatment. We also highlight the current understanding of the cancer signaling pathways that these drugs target.

A Cross-Talk about Radioresistance in Lung Cancer-How to Improve Radiosensitivity According to Chinese Medicine and Medicaments That Commonly Occur in Pharmacies

Lung cancer is one of the most common cancers in the population and is characterized by non-specific symptoms that delay the diagnosis and reduce the effectiveness of oncological treatment. Due to the difficult placement of the tumor, one of the main methods of lung cancer treatment is radiotherapy, which damages the DNA of cancer cells, inducing their apoptosis. However, resistance to ionizing radiation may develop during radiotherapy cycles, leading to an increase in the number of DNA points of control that protect cells from apoptosis. Cancer stem cells are essential for radioresistance, and due to their ability to undergo epithelial-mesenchymal transition, they modify the phenotype, bypassing the genotoxic effect of radiotherapy. It is therefore necessary to search for new methods that could improve the cytotoxic effect of cells through new mechanisms of action. Chinese medicine, with several thousand years of tradition, offers a wide range of possibilities in the search for compounds that could be used in conventional medicine. This review introduces the potential candidates that may present a radiosensitizing effect on lung cancer cells, breaking their radioresistance. Additionally, it includes candidates taken from conventional medicine-drugs commonly available in pharmacies, which may also be significant candidates.

Chromatin remodeling by the histone methyltransferase EZH2 drives lung pre-malignancy and is a target for cancer prevention

Background

Trimethylation of lysine 27 and dimethylation of lysine 9 of histone-H3 catalyzed by the histone methyltransferases EZH2 and G9a impede gene transcription in cancer. Our human bronchial epithelial (HBEC) pre-malignancy model studied the role of these histone modifications in transformation. Tobacco carcinogen transformed HBEC lines were characterized for cytosine DNA methylation, transcriptome reprogramming, and the effect of inhibiting EZH2 and G9a on the transformed phenotype. The effects of targeting EZH2 and G9a on lung cancer prevention was assessed in the A/J mouse lung tumor model.

Results

Carcinogen exposure induced transformation and DNA methylation of 12–96 genes in the four HBEC transformed (T) lines that was perpetuated in malignant tumors. In contrast, 506 unmethylated genes showed reduced expression in one or more HBECTs with many becoming methylated in tumors. ChIP-on-chip for HBEC2T identified 327 and 143 genes enriched for H3K27me3 and H3K9me2. Treatment of HBEC2T and HBEC13T with DZNep, a lysine methyltransferase inhibitor depleted EZH2, reversed transformation, and induced transcriptional reprogramming. The EZH2 small molecule inhibitor EPZ6438 also affected transformation and expression in HBEC2T, while a G9a inhibitor, UNC0642 was ineffective. Genetic knock down of EZH2 dramatically reduced carcinogen-induced transformation of HBEC2. Only DZNep treatment prevented progression of hyperplasia to adenomas in the NNK mouse lung tumor model through reducing EZH2 and affecting the expression of genes regulating cell growth and invasion.

Conclusion

These studies demonstrate a critical role for EZH2 catalyzed histone modifications for premalignancy and its potential as a target for chemoprevention of lung carcinogenesis.

Effects of PPAR-γ agonists on oral cancer cell lines: Potential horizons for chemopreventives and adjunctive therapies

BACKGROUND

Peroxisome proliferator-activated receptor-gamma (PPAR-γ) activators have anti-cancer effects. Our objective was to determine the effect of PPAR-γ ligands 15-deoxy-D^12,14 -Prostaglandin J₂ (15-PGJ₂ ) and ciglitazone on proliferation, apoptosis, and NF-κB in human oral squamous cell carcinoma cell lines.

METHODS

NA and CA9-22 cells were treated in vitro with 15-PGJ₂ and ciglitazone. Proliferation was measured by MTT colorimetric assay and cell cycle analysis performed via flow cytometry, apoptosis by caspase-3 colorimetric assay and poly-(ADP-ribose) polymerase cleavage on Western blot, and NF-κB activation by luciferase assays.

RESULTS

MTT assays demonstrated dose-dependent decreases after 15-PGJ₂ treatment in both cell lines, and S-phase cell cycle arrest was also demonstrated. NF-κB luciferase reporter gene activity decreased seven- and eightfold in NA and CA9-22 cells, respectively. Caspase-3 activity increased two- and eightfold in NA and CA9-22 cells, respectively.

CONCLUSIONS

Our results suggest these agents, in addition to activating PPAR-γ, can downregulate NF-κB and potentiate apoptosis in oral cancer cells.

Synthesis, In Vitro Anticancer, Anti-Inflammatory and DNA Binding Activity of Thiazolidinedione Derivatives

BACKGROUND

Cancer is the second leading cause of mortality worldwide. Despite several advances made in the treatment strategies, the cure for cancer remains still a challenge. Currently used treatment modalities pose several side effects and remain ineffective in the later stages. Thiazolidinediones (TZDs) have been shown to possess anti-cancer activity in several in vitro models.

OBJECTIVES

The objective of this study was to assess the effect of novel synthesized thiazolidinedione derivatives on three selected cancer cell lines viz., human breast adenocarcinoma cell line (MCF-7), lung adenocarcinoma (A549) and colorectal carcinoma (HT29). This study also aimed to evaluate the anti-inflammatory and DNA binding activity of the synthesized derivatives.

METHODS

The synthesized thiazolidinedione derivatives were screened for their in vitro anti-cancer activity on the human breast adenocarcinoma cell line (MCF-7), lung adenocarcinoma (A549) and colorectal carcinoma (HT29) using the Methyl Thaizolyl Tetrazolium (MTT) Assay. They were also evaluated for in vitro antiinflammatory activity using albumin denaturation method, DNA binding activity and hemocompatibility.

RESULTS

Compounds 5a, 5b, 5d, 6c and 6d showed IC50 of 30.19, 41.56, 65.97, 60.16 and 50.41μM respectively on breast adenocarcinoma (MCF-7), IC50 of 49.75, 51.42, 65.43, 61.94 and 56.80μM on lung adenocarcinoma (A549) and 38.11, 45.58, 71.24, 53.15 and 51.25μM on colorectal carcinoma (HT29). In the hemolysis assay, compounds 5a and 5b were found to be nontoxic and nonhemolytic to human erythrocytes. Five compounds possessed significant anticancer and anti-inflammatory activity. Three of them are Mannich bases, whereas the remaining two are aryl acyl derivatives.

CONCLUSION

The in vitro results (anticancer and anti-inflammatory) showed that the 4-chloro anilinomethyl substitution at third position and thiophenoethenyl at the fifth position of thiozolidinedione (5a) emerged as the most effective derivative on all the tested cancer cell lines. A higher DNA binding affinity of the test compounds was also found.

Astaxanthin anticancer effects are mediated through multiple molecular mechanisms: A systematic review

During the latest decades, the interest on the effectiveness of natural compounds and their impact on human health constantly increased, especially on those demonstrating to be effective on cancer. Molecules coming from nature are currently used in chemotherapy like Taxol, Vincristine or Vinblastine, and several other natural substances have been showed to be active in reducing cancer cell progression and migration. Among them, astaxanthin, a xanthophyll red colored carotenoid, displayed different biological activities including, antinflammatory, antioxidant, proapoptotic, and anticancer effects. It can induce apoptosis through downregulation of antiapoptotic protein (Bcl-2, p-Bad, and survivin) expression and upregulation of proapoptotic ones (Bax/Bad and PARP). Thanks to these mechanisms, it can exert anticancer effects towards colorectal cancer, melanoma, or gastric carcinoma cell lines. Moreover, it possesses antiproliferative activity in many experimental models and enhances the effectiveness of conventional chemotherapic drugs on tumor cells underling its potential future use. This review provides an overview of the current knowledge on the anticancer potential of astaxanthin by modulating several molecular targets. While it has been clearly demonstrated its multitarget activity in the prevention and regression of malignant cells in in vitro or in preclinical investigations, further clinical studies are needed to assess its real potential as anticancer in humans.

A Randomized Phase II Trial of Pioglitazone for Lung Cancer Chemoprevention in High-Risk Current and Former Smokers

Lung cancer chemoprevention, especially in high-risk former smokers, has great potential to reduce lung cancer incidence and mortality. Thiazolidinediones prevent lung cancer in preclinical studies, and diabetics receiving thiazolidinediones have lower lung cancer rates which led to our double-blind, randomized, phase II placebo-controlled trial of oral pioglitazone in high-risk current or former smokers with sputum cytologic atypia or known endobronchial dysplasia. Bronchoscopy was performed at study entry and after completing 6 months of treatment. Biopsies were histologically scored, and primary endpoint analysis tested worst biopsy scores (Max) between groups; Dysplasia index (DI) and average score (Avg) changes were secondary endpoints. Biopsies also received an inflammation score. The trial accrued 92 subjects (47 pioglitazone, 45 placebo), and 76 completed both bronchoscopies (39 pioglitazone, 37 placebo). Baseline dysplasia was significantly worse for current smokers, and 64% of subjects had mild or greater dysplasia at study entry. Subjects receiving pioglitazone did not exhibit improvement in bronchial dysplasia. Former smokers treated with pioglitazone exhibited a slight improvement in Max, while current smokers exhibited slight worsening. While statistically significant changes in Avg and DI were not observed in the treatment group, former smokers exhibited a slight decrease in both Avg and DI. Negligible Avg and DI changes occurred in current smokers. A trend toward decreased Ki-67 labeling index occurred in former smokers with baseline dysplasia receiving pioglitazone. While pioglitazone did not improve endobronchial histology in this high-risk cohort, specific lesions showed histologic improvement, and further study is needed to better characterize responsive dysplasia.

Metformin induces lipogenic differentiation in myofibroblasts to reverse lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal disease in which the intricate alveolar network of the lung is progressively replaced by fibrotic scars. Myofibroblasts are the effector cells that excessively deposit extracellular matrix proteins thus compromising lung structure and function. Emerging literature suggests a correlation between fibrosis and metabolic alterations in IPF. In this study, we show that the first-line antidiabetic drug metformin exerts potent antifibrotic effects in the lung by modulating metabolic pathways, inhibiting TGFβ1 action, suppressing collagen formation, activating PPARγ signaling and inducing lipogenic differentiation in lung fibroblasts derived from IPF patients. Using genetic lineage tracing in a murine model of lung fibrosis, we show that metformin alters the fate of myofibroblasts and accelerates fibrosis resolution by inducing myofibroblast-to-lipofibroblast transdifferentiation. Detailed pathway analysis revealed a two-arm mechanism by which metformin accelerates fibrosis resolution. Our data report an antifibrotic role for metformin in the lung, thus warranting further therapeutic evaluation.

Idiopathic pulmonary fibrosis is associated with myofibroblast activation in the lungs and metabolic alterations. Here, the authors show that the antidiabetic drug metformin has antifibrotic effects in human-derived samples and mouse models, by modulating a number of metabolic pathways to induce lipogenic transdifferentiation of myofibroblasts.

The effect of combined treatment with sodium phenylbutyrate and cisplatin, erlotinib, or gefitinib on resistant NSCLC cells

Background

Chemotherapy resistance is the main cause of the marginal clinical benefit of platinum-based chemotherapy and tyrosine kinase inhibitors in advanced non-small-cell lung cancer (NSCLC). Thus, the identification of new therapeutic agents that can enhance the sensitivity of these drugs is of clinical importance. Histone deacetylase inhibitors (HDACIs) are emerging as new promising agents with strong antiproliferative effects against different types of cancers. This study investigates the synergistic potential of sodium phenylbutyrate (NaPB) added on top of standard chemotherapy used against NSCLC.

Objective

The objective of this study was to evaluate the ability of NaPB to overcome the resistance of NSCLC cell lines to cisplatin, gefitinib, and erlotinib.

Methods

MTT cell proliferation assay was used to measure the anticancer effects of cisplatin, erlotinib, or gefitinib alone or combined with various concentrations of NaPB against A549, Calu1, and H1650 NSCLC cell lines. Synergism was estimated by measuring synergy value (R), which is equal to the ratio of IC₅₀ of each primary drug alone divided by combination IC₅₀s. Student’s t-test analysis was used to evaluate the potential differences between IC₅₀ values. ANOVA followed by Tukey’s post hoc was used to evaluate the potential differences among monotherapy and combination treatment groups. Analyses were performed using R 3.3.2 software. P-value <0.05 was considered to be statistically significant.

Results

NaPB was shown to inhibit the growth of A549, Calu1, and H1650 cell lines in a dose-dependent manner (IC₅₀ 10, 8.53, and 4.53 mM, respectively). Furthermore, the addition of NaPB along with cisplatin, erlotinib, or gefitinib to A549, Calu1, and H1650 cell lines resulted in a synergistic antiproliferative effect against the three NSCLC cell lines (R>1.6, P-value <0.05), thus suggesting that NaPB can potentiate the effect of cisplatin, erlotinib, and gefitinib on A549, Calu1, and H1650 cell lines.

Conclusion

Current results suggest a potential role of NaPB as a sensitizing agent in NSCLC.

New insights into molecular mechanisms of rosiglitazone in monotherapy or combination therapy against cancers

Rosiglitazone (ROSI), a member of thiazolidinediones (TZDs) which act as high-affinity agonists of the nuclear receptor peroxisome-proliferator-activated receptor-γ (PPARγ), is clinically used as an antidiabetic drug which could attenuate the insulin resistance associated with obesity, hypertension, and impaired glucose tolerance in humans. However, recent studies reported that ROSI had significant anticancer effects on various human malignant tumor cells. Mounting evidence indicated that ROSI could exert anticancer effects through PPARγ-dependent or PPARγ-independent ways. In this review, we summarized the PPARγ-dependent antitumor activities of ROSI, which included apoptosis induction, inhibition of cell proliferation and cancer metastasis, reversion of multidrug resistance, reduction of immune suppression, autophagy induction, and antiangiogenesis; and the PPARγ-independent antitumor activities of ROSI, which included inhibition of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway, inhibition of prostaglandin E2 (PGE₂), increasing MAPK phosphatase 1 (MKP-1) expression and regulation of other apoptosis-related cell factors. In addition, we discussed the anti-cancer application of ROSI by monotherapy or combination therapy with present chemotherapeutic drugs in vitro and in vivo. Moreover, we reviewed the phase I cancer clinical trials related to ROSI combined with chemotherapeutics and phase II trials about the anti-cancer effects of ROSI monotherapy and the radiotherapy sensitivity of ROSI.

PPARγ as a Novel Therapeutic Target in Lung Cancer

Lung cancer is the leading cause of cancer-related death, with more than half the patients having advanced-stage disease at the time of initial diagnosis and thus facing a poor prognosis. This dire situation poses a need for new approaches in prevention and treatment. Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated transcription factor belonging to the nuclear hormone receptor superfamily. Its involvement in adipocyte differentiation and glucose and lipid homeostasis is well-recognized, but accumulating evidence now suggests that PPARγ may also function as a tumor suppressor, inhibiting development of primary tumors and metastases in lung cancer and other malignancies. Besides having prodifferentiation, antiproliferative, and proapoptotic effects, PPARγ agonists have been shown to prevent cancer cells from acquiring the migratory and invasive capabilities essential for successful metastasis. Angiogenesis and secretion of certain matrix metalloproteinases and extracellular matrix proteins within the tumor microenvironment are also regulated by PPARγ. This review of the current literature highlights the potential of PPARγ agonists as novel therapeutic modalities in lung cancer, either as monotherapy or in combination with standard cytotoxic chemotherapy.

Chemotherapy and chemoprevention by thiazolidinediones

Thiazolidinediones (TZDs) are synthetic ligands of Peroxisome-Proliferator-Activated Receptor gamma (PPARγ). Troglitazone, rosiglitazone, and pioglitazone have been approved for treatment of diabetes mellitus type II. All three compounds, together with the first TZD ciglitazone, also showed an antitumor effect in preclinical studies and a beneficial effect in some clinical trials. This review summarizes hypotheses on the role of PPARγ in tumors, on cellular targets of TZDs, antitumor effects of monotherapy and of TZDs in combination with other compounds, with a focus on their role in the treatment of differentiated thyroid carcinoma. The results of chemopreventive effects of TZDs are also considered. Existing data suggest that the action of TZDs is highly complex and that actions do not correlate with cellular PPARγ expression status. Effects are cell-, species-, and compound-specific and concentration-dependent. Data from human trials suggest the efficacy of TZDs as monotherapy in prostate cancer and glioma and as chemopreventive agent in colon, lung, and breast cancer. TZDs in combination with other therapies might increase antitumor effects in thyroid cancer, soft tissue sarcoma, and melanoma.

Pioglitazone inhibits the proliferation and metastasis of human pancreatic cancer cells

Proliferator-activated receptor-γ (PPAR-γ) is a nuclear receptor that acts as a transcription factor in several types of tissue. PPAR-γ ligands are known to inhibit numerous cancer cell processes, including pancreatic cancer cell proliferation through terminal differentiation. Previous studies concerning the inhibitory effect of PPAR-γ ligands derived from thiazolidinediones (TZDs) on the metastatic potential of cancer cells have been reported. The present study aimed to investigate whether pioglitazone, a prescription TZD class drug and a ligand of PPAR-γ, inhibits the proliferation and metastasis of pancreatic cancer cells. The inhibitory effect of pioglitazone on the proliferation of the Capan-1, Aspc-1, BxPC-3, PANC-1 and MIApaCa-2 pancreatic cancer cell lines was analyzed. Alterations in carcinoembryonic antigen (CEA), interleukin-8 (IL-8) and cyclooxygenase-2 (COX-2) mRNA expression levels subsequent to pioglitazone treatment were examined in BxPC-3 cells by quantitative reverse transcription polymerase chain reaction. In addition, whether the oral administration of pioglitazone prevents tumorigenesis and spontaneous BxPC-3 cell lymph node and lung metastases was investigated using a rectal xenograft model. Pioglitazone treatment resulted in the inhibition of proliferation in all five pancreatic cancer cell lines in vitro. Pioglitazone induced CEA mRNA expression, suppressed IL-8 and COX-2 mRNA expression in vitro, and inhibited BxPC-3 xenograft growth. Pioglitazone also reduced BxPC-3 cell lymph node and lung metastasis in the rectal xenograft model. These results suggest that pioglitazone treatment inhibited the proliferation and metastasis of pancreatic cancer cells through the induction of differentiation and the inhibition of angiogenesis-associated protein expression.

Hydralazine-valproate: a repositioned drug combination for the epigenetic therapy of cancer

INTRODUCTION

DNA methylation (DNMTi) and histone deacetylase inhibitors (HDACi) are in development for cancer therapy. So far, four epigenetic drugs are approved for myelodysplastic syndrome (MDS) and cutaneous T-cell lymphoma (CTCL). The combination of hydralazine-valproate (TRANSKRIP(™)) is being repositioned as an oral DNMT and HDAC inhibitor.

AREAS COVERED

Brief discussion on the current status of epigenetic drugs and studies published on the preclinical and clinical development of the hydralazine-valproate combination.

EXPERT OPINION

Drug repositioning is a strategy for prompt and cost-efficient drug discovery. There is evidence that combining DNMTi with HDACi would be more efficacious than administering each agent on its own. Hydralazine-valproate is safe when used alone or in combination with chemotherapy or chemoradiation. The fact that both drugs are orally administered is another advantage over current epigenetic drugs. This combination is promising but larger studies are needed. Among these, the randomized Phase III trials in advanced and in locally advanced cervical cancer combined with chemotherapy and cisplatin-radiation respectively, would eventually confirm its efficacy. Studies on MDS and CTCL would also eventually prove the efficacy of hydralazine valproate so that in the coming years hydralazine-valproate could have a role in cancer epigenetic therapy.

Positive and negative effects of glitazones in carcinogenesis: experimental models vs. clinical practice

Diabetes increases cancer risk, which may be modulated by careful choice of treatment. Experimental reports showed efficacy of glitazones in various in vitro and in vivo models of carcinogenesis, but procarcinogenic effects in some models were reported too, and, similarly, data on cancer incidence in glitazone users are inconsistent. This review summarizes oncostatic effects of glitazones in preclinical and clinical studies and brings a brief summary of their impact on cancer risk in diabetic patients, with a focus on the association between pioglitazone use and bladder cancer.

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.

PPARγ in head and neck cancer prevention

Head and neck cancer is a major source of morbidity and mortality worldwide. Intervention during the early phases of carcinogenesis represents a promising new strategy for curbing the devastating effects of this disease and its primary treatment modalities, surgery and radiation with or without concomitant chemotherapy. This review focuses on the peroxisome proliferator-activated receptor gamma (PPARγ) as a target for chemoprevention of oral cancer. Accumulating data suggest that ligands of PPARγ, which include the thiazolidinedione class of agents approved for the treatment of diabetes, inhibit cancer cell growth in vitro and in animal carcinogenesis models, providing the rationale for testing this approach in populations at risk for head and neck cancer.

PPARγ-dependent pathway in the growth-inhibitory effects of K562 cells by carotenoids in combination with rosiglitazone

BACKGROUND

Carotenoids have been found to play roles in the prevention and therapy of some cancers which PPARγ was also discovered to be involved in. The present studies were directed to determine the inhibitory effects of carotenoids in combination with rosiglitazone, a synthetic PPARγ agonist, on K562 cell proliferation and elucidate the contribution of PPARγ-dependent pathway to cell proliferation suppression.

METHODS

The effects of carotenoid and rosiglitazone combination on K562 cell proliferation were evaluated by trypan blue dye exclusion assay and MTT assay. When PPARγ has been inhibited by GW9662 and siRNA, cycle-related regulator expression in K562 cells treated with carotenoid and rosiglitazone combination was analyzed by Western blotting.

RESULTS

Rosiglitazone inhibited K562 cell proliferation and augmented the inhibitory effects of carotenoids on the cell proliferation greatly. Specific PPARγ inhibition attenuated the cell growth suppression induced by carotenoid and rosiglitazone combination. GW9662 pre-treatment attenuated the enhanced up-regulation of PPARγ expression caused by the combination treatment. Moreover, GW9662 and PPARγ siRNA also significantly attenuated the up-regulation of p21 and down-regulation of cyclin D1 caused by carotenoids and rosiglitazone.

CONCLUSIONS

PPARγ signaling pathway, via stimulating p21 and inhibiting cyclin D1, may play an important role in the anti-proliferative effects of carotenoid and rosiglitazone combination on K562 cells.

GENERAL SIGNIFICANCE

Carotenoids in combination with rosiglitazone are hopeful to provide attractive dietary or supplementation-based and pharmaceutical strategies to treat cancer diseases.

Effects of rosiglitazone on the growth and lymphangiogenesis of human gastric cancer transplanted in nude mice

Gastric cancer mainly metastasizes via lymphatic vessels. Thus, it is critical to identify efficacious chemopreventive agents for lymphangiogenesis. The present study was undertaken to explore the effects of rosiglitazone (ROSI) on the growth and lymphangiogenesis of human gastric cancer. We established a model of gastric cancer by subcutaneously inoculating the human gastric cancer cell line SGC-7901 into nude mice. Mice were randomly divided into 4 groups and each group received a different agent by oral gavage. The control group received normal saline and treatment groups received different doses of ROSI once every 2 days. The growth of the tumor in vivo was assessed by measuring tumor volume. After 42 days, the mice were sacrificed and the tumors were removed. H&E staining was used to observe the histomorphological features; immunohistochemistry staining for lymphatic vessel density (LVD) was used to evaluate tumor lymphangiogenesis, RT-PCR was performed to determine the mRNA expression of vascular endothelial growth factor C (VEGF-C) and VEGF receptor-3 (VEGFR-3), and western blotting was used to detect the protein expression of VEGF-C and VEGFR-3. Compared with the control group, all treatment groups had smaller tumor volume and higher tumor growth inhibitory rate every day. The number of typical tumor cells in the control group was higher compared to that in the treatment groups, and the highest level of LVD was found in the control group. Furthermore, both the expression of VEGF-C and VEGFR-3 mRNA and proteins in the control group were significantly higher compared to those in the treatment groups. Markedly, these changes were correlated in a dose-dependent manner with ROSI. These results demonstrated that, through simultaneously blocking the expression of VEGF-C and VEGFR-3, ROSI suppresses lymphangiogenesis. This may represent a powerful therapeutic approach for controlling gastric cancer cell growth and metastasis.

Lung cancer chemoprevention: current status and future prospects

Lung cancer is the leading cause of cancer death worldwide, making it an attractive disease for chemoprevention. Although avoidance of tobacco use and smoking cessation will have the greatest impact on lung cancer development, chemoprevention could prove to be very effective, particularly in former smokers. Chemoprevention is the use of agents to reverse or inhibit carcinogenesis and has been successfully applied to other common malignancies. Despite prior studies in lung cancer chemoprevention failing to identify effective agents, we now have the ability to identify high-risk populations, and our understanding of lung tumour and premalignant biology continues to advance. There are distinct histological lesions that can be reproducibly graded as precursors of non-small-cell lung cancer and similar precursor lesions exist for adenocarcinoma. These premalignant lesions are being targeted by chemopreventive agents in current trials and will continue to be studied in the future. In addition, biomarkers that predict risk and response to targeted agents are being investigated and validated. In this Review, we discuss the principles of chemoprevention, data from preclinical models, completed clinical trials and observational studies, and describe new treatments for novel targeted pathways and future chemopreventive efforts.

Chemoprevention of lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

Lung cancer is the most common cause of cancer death in men and women in the United States. Cigarette smoking is the main risk factor. Former smokers are at a substantially increased risk of developing lung cancer compared with lifetime never smokers. Chemoprevention refers to the use of specific agents to reverse, suppress, or prevent the process of carcinogenesis. This article reviews the major agents that have been studied for chemoprevention.

METHODS

Articles of primary, secondary, and tertiary prevention trials were reviewed and summarized to obtain recommendations.

RESULTS

None of the phase 3 trials with the agents β-carotene, retinol, 13-cis-retinoic acid, α-tocopherol, N-acetylcysteine, acetylsalicylic acid, or selenium has demonstrated beneficial and reproducible results. To facilitate the evaluation of promising agents and to lessen the need for a large sample size, extensive time commitment, and expense, surrogate end point biomarker trials are being conducted to assist in identifying the most promising agents for later-stage chemoprevention trials. With the understanding of important cellular signaling pathways and the expansion of potentially important targets, agents (many of which target inflammation and the arachidonic acid pathway) are being developed and tested which may prevent or reverse lung carcinogenesis.

CONCLUSIONS

By integrating biologic knowledge, additional early-phase trials can be performed in a reasonable time frame. The future of lung cancer chemoprevention should entail the evaluation of single agents or combinations that target various pathways while working toward identification and validation of intermediate end points.

Low-dose gamma-radiation inhibits benzo[a]pyrene-induced lung adenoma development in a/j mice

Low-dose ionizing radiation (LDR) may lead to suppression of smoking-related lung cancer. We examined the effects of a known cigarette smoke carcinogen Benzo[a]pyrene (B[a]P) alone or in combination with fractionated low-dose gamma radiation (60 - 600 mGy total dose) on the induction of lung neoplasms in the A/J mouse. Our results show that 600 mGy of gamma radiation delivered in six biweekly fractions of 100 mGy starting 1 month after B[a]P injection significantly inhibits the development of lung adenomas per animal induced by B[a]P. Our data also indicated that the six biweekly doses suppressed the occurrence of spontaneous hyperplastic foci in the lung, although this suppression failed to reach statistical significance when analyzed as average foci per lung possibly related to the small sample sizes used for the control and test groups.

Lung cancer chemoprevention: difficulties, promise and potential agents?

INTRODUCTION

In a variety of cancers there is evidence that specific regimens can prevent or significantly delay the development of cancer. Thus, for breast cancer (ER+) use of SERMs or aromatase inhibitors can substantially decrease tumor incidence. For cervical cancer, HPV vaccination will inhibit long term cancer incidence. For colon cancer, the second greatest cancer killer, administration of aspirin and other NSAIDs decreases advanced colon adenomas in Phase II trials and epidemiologic data support their ability to prevent colon cancer. To date prevention trials in the area of lung cancer have shown minimal efficacy.

AREAS COVERED

The paper examines and discusses in greater detail certain promising agents which the authors have tested either preclinically and or in early phase clinical trials. These agents include RXR agonists, EGFr inhibitors, NSAIDs and Triterpenoids. Other agents including glucocorticoids, pioglitazone and iloprost are briefly mentioned. In addition, the paper presents various types of potential Phase II lung cancer prevention trials and describes their strengths and weaknesses. The potential use of various biomarkers as endpoints in trials e.g. histopathology, non-specific biomarkers (e.g., Ki67, cyclin D expression, apoptosis) and molecular biomarkers (e.g. specific phosphorylated proteins, gene expression etc.) is presented. Finally, we examine at least one approach, the use of aerosols, which may diminish the systemic toxicity associated with certain of these agents.

EXPERT OPINION

The manuscript presents: a) a number of promising agents which appear applicable to further Phase II prevention trials; b) approaches to defining potential preventive agents as well; c) approaches which might mitigate the side effects associated with potential agents most specifically the use of aerosols. Finally, we discuss biomarker studies both preclinical and clinical which might help support potential Phase II trials. The particular appeal to the preclinical studies is that they can be followed to a tumor endpoint. We hope that this will give the reader further background and allow one to appreciate the potential and some of the hurdles associated with lung cancer chemoprevention.

Emerging PPARγ-Independent Role of PPARγ Ligands in Lung Diseases

Peroxisome proliferator activated receptor (PPAR)-γ is a nuclear hormone receptor that is activated by multiple agonists including thiazolidinediones, prostaglandins, and synthetic oleanolic acids. Many PPARγ ligands are under investigation as potential therapies for human diseases. These ligands modulate multiple cellular pathways via both PPARγ-dependent and PPARγ-independent mechanisms. Here, we review the role of PPARγ and PPARγ ligands in lung disease, with emphasis on PPARγ-independent effects. PPARγ ligands show great promise in moderating lung inflammation, as antiproliferative agents in combination to enhance standard chemotherapy in lung cancer and as treatments for pulmonary fibrosis, a progressive fatal disease with no effective therapy. Some of these effects occur when PPARγ is pharmaceutically antagonized or genetically PPARγ and are thus independent of classical PPARγ-dependent transcriptional control. Many PPARγ ligands demonstrate direct binding to transcription factors and other proteins, altering their function and contributing to PPARγ-independent inhibition of disease phenotypes. These PPARγ-independent mechanisms are of significant interest because they suggest new therapeutic uses for currently approved drugs and because they can be used as probes to identify novel proteins and pathways involved in the pathogenesis or treatment of disease, which can then be targeted for further investigation and drug development.

E-cadherin as a predictive marker of brain metastasis in non-small-cell lung cancer, and its regulation by pioglitazone in a preclinical model

It remains unclear whether patients with non-small-cell lung cancer (NSCLC) develop brain metastasis during or after standard therapy. We attempted to identify biological markers that predict brain metastasis, and investigated how to modulate expression of such markers. A case-control study of patients who were newly diagnosed with NSCLC and who had developed brain metastasis during follow-up was conducted between 2004 and 2009. These patients were compared with a control group of patients who had NSCLC but no evidence of brain metastasis. Immunohistochemical analysis of expression of Ki-67, p53, Bcl-2, Bax, vascular endothelial growth factor, epidermal growth factor receptor, caspase-3, and E-cadherin was conducted. The methylation status of the genes for O(6)-methylguanine-DNA-methyltransferase, tissue inhibitor of matrix metalloproteinase (TIMP)-2, TIMP-3, and death-associated protein-kinase was also determined, by use of a methylation-specific polymerase chain reaction. A significantly increased risk of developing brain metastasis was associated with the presence of primary tumors with low E-cadherin expression in patients with NSCLC. We also investigated the effects of pioglitazone, a peroxisome proliferator-activated receptor γ-activating drug, in tumor-bearing mouse models. We found that E-cadherin expression was proportional to pioglitazone exposure time. Interestingly, pioglitazone pretreatment before cancer cell inoculation prevented loss of E-cadherin expression and reduced expression of MMP9 and fibronectin, compared with the control group. E-cadherin expression could be a predictor of brain metastasis in patients with NSCLC. Preventive treatment with pioglitazone may be useful for modulating E-cadherin expression.

Cell signaling molecules as drug targets in lung cancer: an overview

PURPOSE OF REVIEW

Lung being one of the vital and essential organs in the body, lung cancer is a major cause of mortality in the modern human society. Lung cancer can be broadly subdivided into nonsmall cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Although NSCLC is sometimes treated with surgery, the advanced and metastatic NSCLC and SCLC usually respond better to chemotherapy and radiation. The most important targets of these chemotherapeutic agents are various intracellular signaling molecules. The primary focus of this review article is to summarize the description of various cell signaling molecules involved in lung cancer development and their regulation by chemotherapeutic agents.

RECENT FINDINGS

Extensive research work in recent years has identified several cellular signaling molecules that may be intricately involved in the complexity of lung cancer. Some of these cell signaling molecules are epidermal growth factor receptors, vascular endothelial growth factor receptors, mammalian target of rapamycin, mitogen-activated protein kinase phosphatase-1, peroxisome proliferator-activated receptor-gamma, matrix metalloproteinases and receptor for advanced glycation end-products.

SUMMARY

The present review will strengthen our current knowledge regarding the efficacy of the above-mentioned cell signaling molecules as potential beneficial drug targets against lung cancer.

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.