N-(4-hydroxyphenyl)retinamide-induced apoptosis triggered by reactive oxygen species is mediated by activation of MAPKs in head and neck squamous carcinoma cells

The interplay of p38 MAPK signaling and mitochondrial metabolism, a dynamic target in cancer and pathological contexts

Mitochondria play a crucial role in cellular metabolism and bioenergetics, orchestrating various cellular processes, including energy production, metabolism, adaptation to stress, and redox balance. Besides, mitochondria regulate cellular metabolic homeostasis through coordination with multiple signaling pathways. Importantly, the p38 mitogen-activated protein kinase (MAPK) signaling pathway is a key player in the intricate communication with mitochondria, influencing various functions. This review explores the multifaced interaction between the mitochondria and p38 MAPK signaling and the consequent impact on metabolic alterations. Overall, the p38 MAPK pathway governs the activities of key mitochondrial proteins, which are involved in mitochondrial biogenesis, oxidative phosphorylation, thermogenesis, and iron homeostasis. Additionally, p38 MAPK contributes to the regulation of mitochondrial responses to oxidative stress and apoptosis induced by cancer therapies or natural substances by coordinating with other pathways responsible for energy homeostasis. Therefore, dysregulation of these interconnected pathways can lead to various pathologies characterized by aberrant metabolism. Consequently, gaining a deeper understanding of the interaction between mitochondria and the p38 MAPK pathway and their implications presents exciting forecasts for novel therapeutic interventions in cancer and other disorders characterized by metabolic dysregulation.

The Role of the Dysregulated JNK Signaling Pathway in the Pathogenesis of Human Diseases and Its Potential Therapeutic Strategies: A Comprehensive Review

JNK is named after c-Jun N-terminal kinase, as it is responsible for phosphorylating c-Jun. As a member of the mitogen-activated protein kinase (MAPK) family, JNK is also known as stress-activated kinase (SAPK) because it can be activated by extracellular stresses including growth factor, UV irradiation, and virus infection. Functionally, JNK regulates various cell behaviors such as cell differentiation, proliferation, survival, and metabolic reprogramming. Dysregulated JNK signaling contributes to several types of human diseases. Although the role of the JNK pathway in a single disease has been summarized in several previous publications, a comprehensive review of its role in multiple kinds of human diseases is missing. In this review, we begin by introducing the landmark discoveries, structures, tissue expression, and activation mechanisms of the JNK pathway. Next, we come to the focus of this work: a comprehensive summary of the role of the deregulated JNK pathway in multiple kinds of diseases. Beyond that, we also discuss the current strategies for targeting the JNK pathway for therapeutic intervention and summarize the application of JNK inhibitors as well as several challenges now faced. We expect that this review can provide a more comprehensive insight into the critical role of the JNK pathway in the pathogenesis of human diseases and hope that it also provides important clues for ameliorating disease conditions.

Quantum chemistry rules retinoid biology

This Perspective discusses how retinol catalyzes resonance energy transfer (RET) reactions pivotally important for mitochondrial energy homeostasis by protein kinase C δ (PKCδ). PKCδ signals to the pyruvate dehydrogenase complex, controlling oxidative phosphorylation. The PKCδ-retinol complex reversibly responds to the redox potential of cytochrome c, that changes with the electron transfer chain workload. In contrast, the natural retinoid anhydroretinol irreversibly activates PKCδ. Its elongated conjugated-double-bond system limits the energy quantum absorbed by RET. Consequently, while capable of triggering the exergonic activating pathway, anhydroretinol fails to activate the endergonic silencing path, trapping PKCδ in the ON position and causing harmful levels of reactive oxygen species. However, physiological retinol levels displace anhydroretinol, buffer cyotoxicity and potentially render anhydroretinol useful for rapid energy generation. Intriguingly, apocarotenoids, the primary products of the mitochondrial β-carotene,9'-10'-oxygenase, have all the anhydroretinol-like features, including modulation of energy homeostasis. We predict significant conceptual advances to stem from further understanding of the retinoid-catalyzed RET.

Stellettin B-Induced Oral Cancer Cell Death via Endoplasmic Reticulum Stress-Mitochondrial Apoptotic and Autophagic Signaling Pathway

Oral squamous cell carcinoma (OSCC) affects tens of thousands of people worldwide. Despite advances in cancer treatment, the 5-year survival rate of patients with late-stage OSCC is low at 50–60%. Therefore, the development of anti-OSCC therapy is necessary. We evaluated the effects of marine-derived triterpene stellettin B in human OC2 and SCC4 cells. Stellettin B dose-dependently decreased the viability of both cell lines, with a significant reduction in OC2 cells at ≥0.1 µM at 24 and 48 h, and in SCC4 cells at ≥1 µM at 24 and 48 h. Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL)-positive cells were significantly observed at 20 µM of stellettin B at 48 h, with the overexpression of cleaved caspase3 and cleaved poly(ADP-ribose) polymerase (PARP). Moreover, mitochondrial respiratory functions were ablated by stellettin B. Autophagy-related LC3-II/LC3-I ratio and Beclin-1 proteins were increased, whereas p62 was decreased. At 20 µM at 48 h, the expression levels of the endoplasmic reticulum (ER) stress biomarkers calnexin and BiP/GRP78 were significantly increased and mitogen-activated protein kinase (MAPK) signaling pathways were activated. Further investigation using the autophagy inhibitor 3-methyladenine (3-MA) demonstrated that it alleviated stellettin B-induced cell death and autophagy. Overall, our findings show that stellettin B induces the ER stress, mitochondrial stress, apoptosis, and autophagy, causing cell death of OSCC cells.

Design, Synthesis, Radiosynthesis and Biological Evaluation of Fenretinide Analogues as Anticancer and Metabolic Syndrome-Preventive Agents

Fenretinide (4-HPR) is a synthetic derivative of all-trans-retinoic acid (ATRA) characterised by improved therapeutic properties and toxicological profile relative to ATRA. 4-HPR has been mostly investigated as an anti-cancer agent, but recent studies showed its promising therapeutic potential for preventing metabolic syndrome. Several biological targets are involved in 4-HPR's activity, leading to the potential use of this molecule for treating different pathologies. However, although 4-HPR displays quite well-understood multitarget promiscuity with regards to pharmacology, interpreting its precise physiological role remains challenging. In addition, despite promising results in vitro, the clinical efficacy of 4-HPR as a chemotherapeutic agent has not been satisfactory so far. Herein, we describe the preparation of a library of 4-HPR analogues, followed by the biological evaluation of their anti-cancer and anti-obesity/diabetic properties. The click-type analogue 3 b showed good capacity to reduce the amount of lipid accumulation in 3T3-L1 adipocytes during differentiation. Furthermore, it showed an IC₅₀ of 0.53±0.8 μM in cell viability tests on breast cancer cell line MCF-7, together with a good selectivity (SI=121) over noncancerous HEK293 cells. Thus, 3 b was selected as a potential PET tracer to study retinoids in vivo, and the radiosynthesis of [¹⁸ F]3b was successfully developed. Unfortunately, the stability of [¹⁸ F]3b turned out to be insufficient to pursue imaging studies.

Cinnamaldehyde Treatment of Prostate Cancer-Associated Fibroblasts Prevents Their Inhibitory Effect on T Cells Through Toll-Like Receptor 4

Introduction

Cancer-associated fibroblasts (CAFs) promote tumor progression; thus, drugs that can modify CAFs need to be identified.

Methods

To test the effect of cinnamaldehyde on prostate CAFs, the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-2H-tetrazolium bromide assay was used to determine their survival. When spleen cells were treated with CAF supernatant, the proliferation of T cells was inhibited as determined by flow cytometry. After cinnamaldehyde treatment, this immunosuppressive function of CAFs was partially reversed. To explore the molecular mechanism, Western blotting and the quantitative real-time polymerase chain reaction were applied, and TLR4-dependent signaling pathway-related protein and mRNA levels were quantified.

Results

Cinnamaldehyde acted on the TLR4-dependent signaling pathway, altering the function of CAFs such that its supernatant no longer inhibited the proliferation of T cells.

Conclusion

These data indicate that cinnamaldehyde can modify the functions of CAFs, which may be helpful for treating tumors. Cinnamaldehyde can suppress CAF T-cell inhibition.

Antineoplastic Agents Targeting Sphingolipid Pathways

Emerging studies in the enigmatic area of bioactive lipids have made many exciting new discoveries in recent years. Once thought to play a strictly structural role in cellular function, it has since been determined that sphingolipids and their metabolites perform a vast variety of cellular functions beyond what was previously believed. Of utmost importance is their role in cellular signaling, for it is now well understood that select sphingolipids serve as bioactive molecules that play critical roles in both cancer cell death and survival, as well as other cellular responses such as chronic inflammation, protection from intestinal pathogens, and intrinsic protection from intestinal contents, each of which are associated with oncogenesis. Importantly, it has been demonstrated time and time again that many different tumors display dysregulation of sphingolipid metabolism, and the exact profile of said dysregulation has been proven to be useful in determining not only the presence of a tumor, but also the susceptibility to various chemotherapeutic drugs, as well as the metastasizing characteristics of the malignancies. Since these discoveries surfaced it has become apparent that the understanding of sphingolipid metabolism and profile will likely become of great importance in the clinic for both chemotherapy and diagnostics of cancer. The goal of this paper is to provide a comprehensive review of the current state of chemotherapeutic agents that target sphingolipid metabolism that are undergoing clinical trials. Additionally, we will formulate questions involving the use of sphingolipid metabolism as chemotherapeutic targets in need of further research.

Reactive oxygen species in cancer stem cells of head and neck squamous cancer

One of the greatest challenges in systemic treatment of head and neck squamous cell carcinoma (HNSCC) is a small tumor cell population, namely, cancer stem-like cells (CSC). CSC can regenerate and maintain a heterogenic tumor by their self-renewal capacity. Their potential ability to be more resistant to and survival after chemo- and radiation therapy was also identified. Further studies have shown that reactive oxygen species (ROS) contribute to this CSC-associated resistance. In this review, we focus on the current knowledge of HNSCC-CSC, with regard to ROS as a possible and novel therapeutic approach in targeting CSC.

Association of Li-Fraumeni Syndrome With Small Cell Carcinoma of the Ovary, Hypercalcemic Type and Concurrent Pleomorphic Liposarcoma of the Cervix

Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT), is a rare, highly lethal malignancy predominantly affecting young adult females. We report a patient with widely metastatic SCCOHT and concurrent uterine cervical pleomorphic liposarcoma. Clinical targeted next-generation sequencing was performed on both neoplasms and demonstrated hemizygous stop-gain TP53 mutations (p.R196*), and wild-type SMARCA4 in both tumors. Microarray analyses of both tumors revealed similar but not identical widespread loss of heterozygosity over most chromosomes associated with loss of chromosomal copy number in the SCCOHT and pleomorphic liposarcoma tumors, amplification of FGFR1 in both tumors, and amplification of MYC in the SCCOHT. Immunohistochemistry demonstrated that SMARCA4 and SMARCB1 were retained in both tumors, and that SMARCA2 expression was retained but TP53 expression was lost in the SCCOHT. Germline testing using Sanger sequencing showed heterozygous TP53 mutation, confirming the diagnosis of Li-Fraumeni syndrome. These findings are novel and for the first time associate SCCOHT with Li-Fraumeni syndrome.

Cell Cycle Arrest and Apoptosis Induced by Porphyromonas gingivalis Require Jun N-Terminal Protein Kinase- and p53-Mediated p38 Activation in Human Trophoblasts

Porphyromonas gingivalis, a periodontal pathogen, has been implicated as a causative agent of preterm delivery of low-birth-weight infants. We previously reported that P. gingivalis activated cellular DNA damage signaling pathways and ERK1/2 that lead to G₁ arrest and apoptosis in extravillous trophoblast cells (HTR-8 cells) derived from the human placenta. In the present study, we further examined alternative signaling pathways mediating cellular damage caused by P. gingivalis. P. gingivalis infection of HTR-8 cells induced phosphorylation of p38 and Jun N-terminal protein kinase (JNK), while their inhibitors diminished both G₁ arrest and apoptosis. In addition, heat shock protein 27 (HSP27) was phosphorylated through both p38 and JNK, and knockdown of HSP27 with small interfering RNA (siRNA) prevented both G₁ arrest and apoptosis. Furthermore, regulation of G₁ arrest and apoptosis was associated with p21 expression. HTR-8 cells infected with P. gingivalis exhibited upregulation of p21, which was regulated by p53 and HSP27. These results suggest that P. gingivalis induces G₁ arrest and apoptosis via novel molecular pathways that involve p38 and JNK with its downstream effectors in human trophoblasts.

Role of JNK signaling in oral cancer: A mini review

JNKs (c-Jun N-terminal kinases) belong to mitogen-activated protein kinases' family and become activated by several growth factors, stress, radiation, and other extracellular signals. In turn, JNK activation results in phosphorylation of downstream molecules involved in many normal cellular processes. Nevertheless, recent data have linked JNK signaling with several pathological conditions, including neurodegenerative diseases, inflammation, and cancer. The role of JNK in cancer remains controversial. Initially, JNK was thought to play a rather oncosuppressive role by mediating apoptosis in response to stress stimuli, inflammatory, or oncogenic signals. However, a number of studies have implicated JNK in malignant transformation and tumor growth. The contradictory functions of JNK in cancer may be due to the diversity of JNK upstream and downstream signaling and are under intensive investigation. This review summarizes current literature focusing on the significance of JNK pathway in cancer development and progression, particularly addressing its role in oral cancer. Understanding the complexity of JNK signaling has the potential to elucidate important molecular aspects of oral cancer, possibly leading to development of novel and individualized therapeutic strategies.

Downregulation of steroid hormone receptor expression and activation of cell signal transduction pathways induced by a chiral nonylphenol isomer in mouse sertoli TM4 cells

Nonylphenols (NPs) are considered as important environmental toxicants and potential endocrine disrupting compounds which can disrupt male reproductive system. 4-[1-Ethyl-1-methylhexy] phenol (4-NP₆₅ ) is one of the main isomers of technical nonylphenol mixtures. In the present study, effect of NPs was evaluated from an isomer-specific viewpoint using 4-NP₆₅ . Decreased mRNA expression levels of estrogen receptor (ER)-α, ER-β, androgen receptor (AR) and progesterone receptor (PR) were observed in the cells exposed to 4-NP₆₅ for 24 h. Furthermore, 4-NP₆₅ treatment evoked significant decrease in protein expression levels of ER-α and ER-β. Levels of mullerian inhibiting substance and transferrin were found to change significantly in 4-NP₆₅ challenged cells. Additionally, JNK1/2-MAPK pathway was activated due to 4-NP₆₅ exposure, but not ERK1/2 and p38-MAPK pathways. Meanwhile, 4-NP₆₅ increased the p-Akt level and showed no effects on the Akt level which indicated that Akt pathway was activated by 4-NP₆₅ . In conclusion, these findings have shown that 4-NP₆₅ exposure affected expression of cell receptors and cell signaling pathways in Sertoli TM4 cells. We proposed that molecular mechanism of reproductive damage in Sertoli cells induced by NPs may be mediated by cell receptors and/or cell signal transduction pathways, and that the effects were dependent on the side chain of NP isomers. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 469-476, 2017.

Effect of borrelidin on hepatocellular carcinoma cells in vitro and in vivo

Hepatocellular carcinoma (HCC) is the most common type of liver cancer with high prevalence and mortality.

Fenretinide (4-HPR) Targets Caspase-9, ERK 1/2 and the Wnt3a/β-Catenin Pathway in Medulloblastoma Cells and Medulloblastoma Cell Spheroids

Medulloblastoma (MB), a neuroectodermal tumor arising in the cerebellum, represents the most frequent childhood brain malignancy. Current treatments for MB combine radiation and chemotherapy and are often associated with relevant side effects; novel therapeutic strategies are urgently needed. N-(4-Hydroxyphenyl) retinamide (4-HPR, fenretinide), a synthetic analogue of all-trans retinoic acid, has emerged as a promising and well-tolerated cancer chemopreventive and chemotherapeutic agent for various neoplasms, from breast cancer to neuroblastoma. Here we investigated the effects of 4-HPR on MB cell lines and identified the mechanism of action for a potential use in therapy of MB. Flow cytometry analysis was performed to evaluate 4-HPR induction of apoptosis and oxygen reactive species (ROS) production, as well as cell cycle effects. Functional analysis to determine 4-HPR ability to interfere with MB cell migration and invasion were performed. Western Blot analysis were used to investigate the crucial molecules involved in selected signaling pathways associated with apoptosis (caspase-9 and PARP-1), cell survival (ERK 1/2) and tumor progression (Wnt3a and β-catenin). We show that 4-HPR induces caspase 9-dependent cell death in DAOY and ONS-76 cells, associated with increased ROS generation, suggesting that free radical intermediates might be directly involved. We observed 4-HPR induction of cell cycle arrest in G1/S phase, inactivated β-catenin, and inhibition of MB cell migration and invasion. We also evaluated the ability of 4-HPR to target MB cancer-stem/cancer-initiating cells, using an MB spheroids model, followed by flow cytometry and quantitative real-time PCR. 4-HPR treatment reduced DAOY and ONS-76 spheroid formation, in term of number and size. Decreased expression of the surface markers CD133⁺ and ABCG2⁺ as well as Oct-4 and Sox-2 gene expression were observed on BTICs treated with 4-HPR further reducing BITIC invasive activities. Finally, we analyzed 4-HPR ability to inhibit MB tumor cell growth in vivo in nude mice. Taken together, our data suggest that 4-HPR targets both parental and MB tumor stem/initiating cell-like populations. Since 4-HPR exerts low toxicity, it could represent a valid compound in the treatment of human MB.

JNK1/2 expression and modulation of STAT3 signaling in oral cancer

Mitogen-activated protein kinases (MAPKs) are a family of protein kinases that link extracellular stimuli with intracellular responses and participate in numerous cellular processes such as growth, proliferation, differentiation, inflammation and apoptosis. Persistent activation of signal transducer and activator of transcription 3 (STAT3), which is accompanied by increases in STAT3 tyrosine phosphorylation, is associated with cell proliferation, differentiation and apoptosis in oral squamous cell carcinoma (OSCC). The role and significance of the activation of MAPKs, particularly of c-Jun N-terminal kinase (JNK), on STAT3 signaling in OSCC have not been thoroughly investigated. The present study examines the effects of JNK1/2 modulation on STAT3 signaling and cellular activities in OSCC cells. The expression levels of STAT3 [total, tyrosine phosphorylated (p-Tyr) and serine phosphorylated (p-Ser)], JNK, c-Jun and cyclin D1 were assessed in the OSCC cell lines SCC25 and SCC9. Inhibition of JNK1/2 was achieved by pharmacological agents (SP600125) and by small interfering RNA (siRNA) silencing, while JNK1/2 was induced by active MAPK kinase 7. Cell proliferation and viability rates were also evaluated. Inhibition of JNK1/2 with either SP600125 treatment or specific siRNA silencing resulted in decreased levels of p-Ser STAT3 and increased levels of p-Tyr STAT3 and cyclin D1 in both cell lines. Furthermore, JNK1/2 inhibition resulted in a dose-dependent increase in cell growth and viability in both cell lines. Opposite results were observed with JNK1/2 induction in both cell lines. The present results are supportive of a potential tumor suppressive role of JNK1/2 signaling in OSCC, which may be mediated through negative crosstalk with the oncogenic STAT3 signaling pathway. The possible therapeutic implications of JNK1/2 inhibition for patients with OSCC require to be investigated.

Parsing Myc Paralogs in Oncogenesis

Myc and its paralog MycN are thought to be functionally redundant, but Myc- and MycN-driven medulloblastomas exhibit distinct phenotypes. In this issue of Cancer Cell, Vo and colleagues (2016) show that this phenotypic difference stems from the preferential ability of Myc, relative to MycN, to bind Miz1 and repress transcription.

Lung Cancer Genomics in the Era of Accelerated Targeted Drug Development

Lung cancer is the leading cause of cancer-related deaths in the United States and the 5-year overall survival outlook for a patient has not improved in several decades. Recently, however, molecular and genomic profiling of the lung tumors has revealed recurring somatic mutations. As a result the therapeutic landscape of lung cancer is undergoing a paradigm shift from a purely histology-based understanding of the disease to subtype distinctions based on tumor genetics, which has launched cancer-specific, mechanism-based targeted therapies with clear benefit to patients. While targeted therapy advancements are being made at an ever increasing rate, a new challenge in the form of drug resistance has also emerged. This review summarizes the current literature for these issues.

Mitogen-activated protein kinase and Akt pathways are involved in 4-n-nonyphenol induced apoptosis in mouse Sertoli TM4 cells

Nonylphenol (NP) is considered an important environmental toxicant, which may disrupt male reproductive system. The aim of this study was to investigate 4-n-nonylphenol (4-n-NP) induced apoptosis and its related mechanism in mouse Sertoli cell line, TM4 cells. Our results showed that NP treatment (0.1, 1, 10, 20 and 30 μM) decreased cell viability and induced apoptosis in the cells, accompanied by alteration of Bcl-2 family mRNA expression, activation of caspases-3, release of Ca(2+), and increase of reactive oxygen species (ROS) generation. Subsequently, it was found that the levels of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-PX) in the cells were markedly decreased, and maleic dialdehyde (MDA) content was increased by NP treatment. Then activation of the mitogen-activated protein kinases (MAPKs) pathways and inhibition of Akt pathway were simultaneously detected in NP challenged TM4 cells. Taken together, it was concluded that NP induced cytotoxicity and apoptosis in TM4 cells, and the apoptosis may be mediated via MAPKs and Akt pathways in addition to Ca(2+) release and ROS generation.

Sinodielide A exerts thermosensitizing effects and induces apoptosis and G2/M cell cycle arrest in DU145 human prostate cancer cells via the Ras/Raf/MAPK and PI3K/Akt signaling pathways

Sinodielide A (SA) is a naturally occurring guaianolide, which is isolated from the root of Sinodielsia yunnanensis. This root, commonly found in Yunnan province, is used in traditional Chinese medicine as an antipyretic, analgesic and diaphoretic agent. A number of studies have reported that agents isolated from a species of Umbelliferae (Apiaceae) have antitumor activities. We previously reported, using combined treatments with this medicinal herb and hyperthermia at various temperatures, an enhanced cytotoxicity in the human prostate cancer androgen‑independent cell lines, PC3 and DU145, and analyzed the related mechanisms. In the present study, we investigated the effects of treatment with SA prior to hyperthermia on the thermosensitivity of DU145 cells, and the mechanisms related to the induction of apoptosis and G(2)/M cell cycle arrest via the activation of extracellular-regulated kinase (ERK)1/2, c-Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) signaling pathways, as well as the phosphoinositide 3-kinase (PI3K)/Akt signaling pathways. Cells were exposed to hyperthermia alone (40-44˚C) or hyperthermia in combination with SA. Lethal damage to cells treated with mild hyperthermia (40 or 42˚C) for up to 6 h was slight; however, hyperthermia in combination with SA synergistically enhanced thermosensivity. Lethal damage to cells treated with acute hyperthermia (43 or 44˚C) was more severe, but these effects were also enhanced and were more significant by the combined treatment with SA. The kinetics of apoptosis induction and cell cycle distribution were analyzed by flow cytometry. In addition, the levels of ERK1/2, JNK and Akt were determined by western blot analysis. The incidence of apoptotic cells after treatment with SA (20.0 µM) at 37˚C for 4 h, hyperthermia (44˚C) alone for 30 min, and the combination in sequence were examined. The sub-G1 division (%) in the diagram obtained by flow cytometry was applied to that assay. The percentage of apoptotic cells (10.53±5.02%) was higher at 48 h as compared to 0, 12 and 24 h after treatment. The distribution of DU145 cells in the G2/M cell cycle phase was markedly increased after 24 h of heating at 44˚C and after the combined treatment with heating and SA. The phosphorylation of ERK1/2 was reduced following treatment with heating and SA, while the levels of phosphorylated JNK (p-JNK) were markedly increased immediately after heating at 44˚C and when heating was combined with SA. By contrast, the levels of phosphorylated Akt (p-Akt) were immediately increased only after heating at 44˚C. Thus, we concluded that SA exerts its thermosensitizing effects on DU145 cells by inhibiting the activation of the MAPK/ERK1/2 and PI3K/Akt signaling pathways.

Advances in personalized therapy for lung cancer

INTRODUCTION

Personalized medicine based on tumor characteristics is transforming the management of lung cancer. This review provides an overview of clinically approved strategies to personalize treatment for lung cancer as well as evolving strategies in various stages of clinical development.

AREAS COVERED

Selecting therapy based on various tumor characteristics such as histology and presence of specific molecular alterations will be covered. This review will not only discuss the role of targeted agents in personalizing care for lung cancer but also the strategies to personalize traditional chemotherapeutic agents.

EXPERT OPINION

Advances in genomic medicine to identify key genetic alterations with subsequent development of matching targeted agents are rapidly changing the management of lung cancer. Being able to target key driver molecular aberrations is certainly exciting and clinically meaningful, but only for a limited period of time. Intra- and intertumoral heterogeneity is a major contributor to therapy resistance, a substantial roadblock to durable response. Better understanding of resistance mechanism is at least as important as identifying new targetable genetic changes to effectively advance personalized therapy for lung cancer. Finally, optimization of biopsy specimens and rigorous validation steps to ensure reliability of diagnostic methods would be critical in moving forward.

Apoptosis of bone marrow mesenchymal stem cells caused by homocysteine via activating JNK signal

Bone marrow mesenchymal stem cells (BMSCs) are capable of homing to and repair damaged myocardial tissues. Apoptosis of BMSCs in response to various pathological stimuli leads to the attenuation of healing ability of BMSCs. Plenty of evidence has shown that elevated homocysteine level is a novel independent risk factor of cardiovascular diseases. The present study was aimed to investigate whether homocysteine may induce apoptosis of BMSCs and its underlying mechanisms. Here we uncovered that homocysteine significantly inhibited the cellular viability of BMSCs. Furthermore, TUNEL, AO/EB, Hoechst 333342 and Live/Death staining demonstrated the apoptotic morphological appearance of BMSCs after homocysteine treatment. A distinct increase of ROS level was also observed in homocysteine-treated BMSCs. The blockage of ROS by DMTU and NAC prevented the apoptosis of BMSCs induced by homocysteine, indicating ROS was involved in the apoptosis of BMSCs. Moreover, homocysteine also caused the depolarization of mitochondrial membrane potential of BMSCs. Furthermore, apoptotic appearance and mitochondrial membrane potential depolarization in homocysteine-treated BMSCs was significantly reversed by JNK inhibitor but not p38 MAPK and ERK inhibitors. Western blot also confirmed that p-JNK was significantly activated after exposing BMSCs to homocysteine. Homocysteine treatment caused a significant reduction of BMSCs-secreted VEGF and IGF-1 in the culture medium. Collectively, elevated homocysteine induced the apoptosis of BMSCs via ROS-induced the activation of JNK signal, which provides more insight into the molecular mechanisms of hyperhomocysteinemia-related cardiovascular diseases.

Bexarotene induces cellular senescence in MMTV-Neu mouse model of mammary carcinogenesis

Previous studies have shown that retinoids and rexinoids can prevent breast cancer in animal models and in women with increased risk of developing the disease. The cellular effects of these vitamin A analogues have been primarily associated with induction of differentiation and inhibition of proliferation. In this study, we tested the hypothesis that bexarotene (LGD1069, Targretin), a rexinoid, can not only inhibit cell proliferation but also induce cellular senescence in mammary epithelial cells, premalignant lesions, and tumors of the MMTV-Neu model of mammary carcinogenesis, which develops estrogen receptor-negative tumors. Mice with palpable mammary tumors were treated for 4 weeks with bexarotene at 80 or 40 mg/kg body weight, and senescent cells were determined by SA-β-Gal assay. Bexarotene decreased in a dose-dependent manner the multiplicity of premalignant lesions and tumors, and this was associated with inhibition of cell proliferation and induction of cellular senescence and apoptosis. By double labeling of senescent cells, first by SA-β-Gal and then by antibodies against genes related to cellular senescence, we found that p21, p16, and RARβ, but not p53, were upregulated by bexarotene in mammary tumors and in breast cancer cell lines, suggesting involvement of multiple signaling pathways in mediating the senescence program of rexinoids. These findings indicate that, in addition to cell proliferation and apoptosis, cellular senescence could be used as a potential biomarker of response in breast cancer prevention and therapy studies with rexinoids and possibly with other antitumor agents.

Association of polymorphisms and haplotype in the region of TRIT1, MYCL1 and MFSD2A with the risk and clinicopathological features of gastric cancer in a southeast Chinese population

To explore the association of polymorphisms in the region of three neighboring genes TRIT1, MYCL1 and MFSD2A with risk and clinicopathological features of gastric cancer, 19 tagging SNPs in this region were genotyped using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in a case-control study of 610 Chinese gastric cancer patients and 608 cancer-free controls. MFSD2A rs4233508 T>C CC genotype was associated with an increased risk of gastric cancer in younger patients and an increased risk of moderately/well-differentiated intestinal-type gastric cancer (adjusted odds ratio [OR], 1.74 and 1.50, respectively). TRIT1 rs11581557 T>G TG was associated with lymph node metastasis (TG versus TT/GG, adjusted OR, 1.64). MFSD2A rs12083239 GC genotype and TRIT1 rs2172362 or rs230310 homozygous genotype were associated with Lauren's classification (GC versus GG, adjusted OR, 1.69; GC versus GG/CC, adjusted OR, 1.74) and tumor site (rs2172362: CC versus CT, adjusted OR, 1.71; CC/TT versus CT, adjusted OR, 1.62; rs230310: CC versus CT, adjusted OR, 1.75; CC/TT versus CT, adjusted OR, 1.67) of gastric cancer, respectively. One TRIT1 haplotype, CCGT, was associated with lymph node metastasis and tumor site of gastric cancer (CCGT versus TTTT, adjusted OR, 1.91 and 1.55). This is believed to be the first report that several tagging SNPs and haplotypes in TRIT1, MYCL1 and MFSD2A region are significantly associated with risk and clinicopathological features of gastric cancer in a Chinese population. The findings might be useful for risk assessment and prognosis prediction of gastric cancer.

Mechanism of maprotiline-induced apoptosis: role of [Ca2+](i), ERK, JNK and caspase-3 signaling pathways

Antidepressants are generally used for treatment of various mood and anxiety disorders. Several studies have shown the anti-tumor and cytotoxic activities of some antidepressants, but the underlying mechanisms were unclear. Maprotiline is a tetracyclic antidepressant and possesses a highly selective norepinephrine reuptake ability. We found that maprotiline decreased cell viability in a concentration- and time-dependent manner in Neuro-2a cells. Maprotiline induced apoptosis and increased caspase-3 activation. The activation of caspase-3 by maprotiline appears to depend on the activation of JNK and the inactivation of ERK. Maprotiline also induced [Ca(2+)](i) increases which involved the mobilization of intracellular Ca(2+) stored in the endoplasmic reticulum. Pretreatment with BAPTA/AM, a Ca(2+) chelator, suppressed maprotiline-induced ERK phosphorylation, enhanced caspase-3 activation and increased maprotiline-induced apoptosis. In conclusion, maprotiline induced apoptosis in Neuro-2a cells through activation of JNK-associated caspase-3 pathways. Maprotiline also evoked an anti-apoptotic response that was both Ca(2+)- and ERK-dependent.

Cell signaling through protein kinase C oxidation and activation

Due to the growing importance of cellular signaling mediated by reactive oxygen species (ROS), proteins that are reversibly modulated by these reactant molecules are of high interest. In this context, protein kinases and phosphatases, which act coordinately in the regulation of signal transduction through the phosphorylation and dephosphorylation of target proteins, have been described to be key elements in ROS-mediated signaling events. The major mechanism by which these proteins may be modified by oxidation involves the presence of key redox-sensitive cysteine residues. Protein kinase C (PKC) is involved in a variety of cellular signaling pathways. These proteins have been shown to contain a unique structural feature that is susceptible to oxidative modification. A large number of scientific studies have highlighted the importance of ROS as a second messenger in numerous cellular processes, including cell proliferation, gene expression, adhesion, differentiation, senescence, and apoptosis. In this context, the goal of this review is to discuss the mechanisms by which PKCs are modulated by ROS and how these processes are involved in the cellular response.

Functional drug-gene interactions in lung cancer

Despite the dawn of the genomic information era, the challenges of cancer treatment remain formidable. Particularly for the most prevalent cancer types, including lung cancer, successful treatment of metastatic disease is rare and escalating costs for modern targeted drugs place an increasing strain on healthcare systems. Although powerful diagnostic tools to characterize individual tumor samples in great molecular detail are becoming rapidly available, the transformation of this information into therapy provides a major challenge. A fundamental difficulty is the molecular complexity of cancer cells that often causes drug resistance, but can also render tumors exquisitely sensitive to targeted agents. By using lung cancer as an example, we outline the principles that govern drug sensitivity and resistance from a genetic perspective and discuss how in vitro chemical-genetic screens can impact on patient stratification in the clinic.

Organotypic modeling of human keratinocyte response to peroxisome proliferators

Peroxisome proliferators (PPs) are a diverse chemical group including hypolipidemic drugs and some fatty acids. Their stimulation of PP-activated receptors (PPARs) and subsequent control of gene expression regulates metabolism and differentiation in many cells. PPs have multiple opportunities to target human epidermal keratinocytes because of delivery through dietary, clinical, and/or topical exposure routes. PPAR knockout mice and PP treatment of mouse skin or human keratinocytes in monolayer culture have established some effects for PPs in cutaneous differentiation. However, incomplete epidermal maturation characteristic of monolayer keratinocytes and rodent-specific effects may limit our full understanding of human keratinocyte responses to PPs. To address these issues, we investigated PP influence on primary human keratinocytes in organotypic cultures that recapitulate biochemical markers of epidermis. We found that the PPARα agonists clofibrate, docasohexaenoic acid, and WY-14,643 produced mild to moderate keratinocyte hyperplasia, increased stratification (particularly of granular and cornified layers), and enhanced levels of the differentiation markers filaggrin, ABCA12, and phosphorylated HSP27. Several PP effects generated in the organotypic system, however, were distinct from those previously reported for rodent skin and human keratinocyte monolayer cultures, suggesting that the species and growth context of target cells can impact exposure outcomes. Given the utility of organotypic cultures for modeling the epidermis, studies in this system may bridge the gap between the rodent assays and clinical studies of human epidermal responses to PPs.

Mitochondria: redox metabolism and dysfunction

Mitochondria are the main intracellular location for fuel generation; however, they are not just power plants but involved in a range of other intracellular functions including regulation of redox homeostasis and cell fate. Dysfunction of mitochondria will result in oxidative stress which is one of the underlying causal factors for a variety of diseases including neurodegenerative diseases, diabetes, cardiovascular diseases, and cancer. In this paper, generation of reactive oxygen/nitrogen species (ROS/RNS) in the mitochondria, redox regulatory roles of certain mitochondrial proteins, and the impact on cell fate will be discussed. The current state of our understanding in mitochondrial dysfunction in pathological states and how we could target them for therapeutic purpose will also be briefly reviewed.

Impact of 4HPR on the expression of E-Cad in human bladder transitional epithelial cancer cells T24

Previous researches showed that the expression level of E-Cad in most infiltrating cancer cells was reduced or negative. This study explored whether 4HPR restrained the infiltration of bladder cancer cells through regulating the expression of E-Cad. The infiltrating bladder cancer cells T24 were cultured, and then treated by a proper dosage of drug. Their viability was a determined by MTT method. Western blotting and RT-PCR were adopted to detect the changes of E-Cad gene expression at both protein and mRNA levels. Moreover, immunofluorescent staining and confocal fluorescence microscopy were employed for the observation of the expression of E-Cad. The result showed that, at both mRNA and protein levels, the expression level of E-Cad in T24 cells treated by 4HPR was significantly higher than that of control group, while the β-Cat expression was also relocated from the cell nucleus to cytoplasm. Our findings suggested that the regulatory function of 4HPR on infiltration of bladder cancer cells T24 is at least partly achieved by regulating the expression of E-Cad.

Dihydroceramide accumulation and reactive oxygen species are distinct and nonessential events in 4-HPR-mediated leukemia cell death

4-(Hydroxyphenyl)retinamide (4-HPR) is a synthetic retinoid with a strong apoptotic effect towards different cancer cell lines in vitro, and it is currently tested in clinical trials. Increases of reactive oxygen species (ROS) and modulation of endogenous sphingolipid levels are well-described events observed upon 4-HPR treatment, but there is still a lack of understanding of their relationship and their contribution to cell death. LC-MS analysis of sphingolipids revealed that in human leukemia CCRF-CEM and Jurkat cells, 4-HPR induced dihydroceramide but not ceramide accumulation even at sublethal concentrations. Myriocin prevented the 4-HPR-induced dihydroceramide accumulation, but it did not prevent the loss of viability and increase of intracellular ROS production. On the other hand, ascorbic acid, Trolox, and vitamin E reversed 4-HPR effects on cell death but not dihydroceramide accumulation. NDGA, described as a lipoxygenase inhibitor, exerted a significantly higher antioxidant activity than vitamin E and abrogated 4-HPR-mediated ROS. It did not however rescue cellular viability. Taken together, this study demonstrates that early changes observed upon 4-HPR treatment, i.e., sphingolipid modulation and ROS production, are mechanistically independent events. Furthermore, the results indicate that 4-HPR-driven cell death may occur even in the absence of dihydroceramide or ROS accumulation. These observations should be taken into account for an improved design of drug combinations.

Stem cells in squamous head and neck cancer

The initiation and metastasis of head and neck squamous cell carcinomas (HNSCC) and other cancers have recently been related to the presence of cancer stem cells (CSC). CSC are cancer initiating, sustaining and are mostly quiescent. Specific markers that vary considerably depending on tumor type or tissue of origin characterize putative CSC. Compared to the bulk tumor mass, CSC are less sensitive to chemo- and radiotherapy and may also have low immunogenicity. Therapeutic targeting of CSC may improve clinical outcome of HNSCC which has two distinct etiologies: infection of epithelial stem cells by high-risk types of the human papillomavirus, or long-term tobacco and alcohol abuse. Recent knowledge on the role of CSC in HNSCC is reviewed and where necessary parallels to CSC of other origin are drawn to give a more comprehensive picture.

Role of Ras-related C3 botulinum toxin substrate 2 (Rac2), NADPH oxidase and reactive oxygen species in diallyl disulphide-induced apoptosis of human leukaemia HL-60 cells

1. Diallyl disulphide (DADS) has potential as a chemopreventive and therapeutic agent. Previous studies have reported that Ras-related C3 botulinum toxin substrate 2 (Rac2), a regulatory subunit of the NADPH oxidase complex, is upregulated in DADS-induced apoptosis in human leukaemia HL-60 cells. The aim of the present study was to investigate the role of Rac2, NADPH oxidase and reactive oxygen species (ROS) in DADS-induced apoptosis. 2. Expression of the Rac2 gene along with that of five other genes of NADPH oxidase subunits were in HL-60 cells measured by Sybergreen quantitative real-time polymerase chain reaction. RNA interference was used to test the effect of Rac2. Protein expression was evaluated using western blot analysis and ROS levels were measured by 2',7'-dichlorofluorescein diacetate (DCFH-DA) fluorescence. DNA fragmentation and flow cytometry analysis were used to detect apoptotic cells. 3. Levels of Rac2 gene and protein were significantly upregulated and NADPH oxidase was activated in DADS-induced apoptosis. Pretreatment of HL-60 cells with small interfering (si) RNAs to inhibit Rac2 blocked DADS-induced apoptosis. Diallyl disulphide-induced intracellular ROS production was increased in phorbol myristate acetate-stimulated cells, but decreased in Rac2 siRNA-treated cells. In Rac2 siRNA-treated cells, activator protein-1 and caspase 3 levels decreased, c-myc protein levels were increased and p38 protein levels were unchanged compared with Rac2-competent, DADS-treated cells. 4. These results demonstrate that NADPH oxidase is the main source of DADS-induced ROS. In addition, Rac2 selectively activates the c-Jun N-terminal kinase pathway, but not the p38 pathway, in DADS-induced apoptosis. So, Rac2, NADPH oxidase and ROS have a critical role in DADS-induced apoptosis in human leukaemia HL-60 cells.

Fenretinide-dependent upregulation of death receptors through ASK1 and p38α enhances death receptor ligand-induced cell death in Ewing's sarcoma family of tumours

Background:

Sustained p38^MAPK phosphorylation upregulates p75 neurotrophin (p75^NTR) and induces apoptosis in Ewing's sarcoma family of tumours (ESFT). As fenretinide induces ESFT death through sustained p38^MAPK phosphorylation, we hypothesised that this may be effected through upregulation of death receptors (DRs) and that treatment of fenretinide plus DR ligands may enhance apoptosis.

Methods:

DR expression was determined by flow cytometry. Trypan blue exclusion assays, caspase-8 flow cytometry and immunoblotting for Bid were used to measure cell death.

Results:

Fenretinide upregulated cell surface expression of tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) receptors, FAS and p75^NTR, in an ASK1- and p38α-dependent manner. Cotreatment with fenretinide and DR ligands resulted in synergistic death compared with either agent alone; caspase-8 and Bid were cleaved in a time-dependent manner. Fenretinide did not increase DR expression in non-malignant cells. Furthermore, fenretinide, TRAIL or a combination of both agents was non-cytotoxic to non-malignant cells. Etoposide and actinomycin D increased expression of all DRs examined, whereas vincristine increased FAS alone. Only actinomycin D and TRAIL, and etoposide with TRAIL or FasL, enhanced death compared with either agent alone.

Conclusion:

The synergistic death observed with fenretinide and DR ligands suggests that this combination may be an attractive strategy for the treatment of ESFT.

MEK-ERK-dependent multiple caspase activation by mitochondrial proapoptotic Bcl-2 family proteins is essential for heavy ion irradiation-induced glioma cell death

Recently developed heavy ion irradiation therapy using a carbon beam (CB) against systemic malignancy has numerous advantages. However, the clinical results of CB therapy against glioblastoma still have room for improvement. Therefore, we tried to clarify the molecular mechanism of CB-induced glioma cell death. T98G and U251 human glioblastoma cell lines were irradiated by CB, and caspase-dependent apoptosis was induced in both cell lines in a dose-dependent manner. Knockdown of Bax (BCL-2-associated X protein) and Bak (BCL-2-associated killer) and overexpression of Bcl-2 or Bcl-xl (B-cell lymphoma-extra large) showed the involvement of Bcl-2 family proteins upstream of caspase activation, including caspase-8, in CB-induced glioma cell death. We also detected the activation of extracellular signal-regulated kinase (ERK) and the knockdown of ERK regulator mitogen-activated protein kinase kinase (MEK)1/2 or overexpression of a dominant-negative (DN) ERK inhibited CB-induced glioma cell death upstream of the mitochondria. In addition, application of MEK-specific inhibitors for defined periods showed that the recovery of activation of ERK between 2 and 36 h after irradiation is essential for CB-induced glioma cell death. Furthermore, MEK inhibitors or overexpression of a DN ERK failed to significantly inhibit X-ray-induced T98G and U251 cell death. These results suggested that the MEK–ERK cascade has a crucial role in CB-induced glioma cell death, which is known to have a limited contribution to X-ray-induced glioma cell death.

Role for PKC δ in Fenretinide-Mediated Apoptosis in Lymphoid Leukemia Cells

The synthetic Vitamin A analog fenretinide is a promising chemotherapeutic agent. In the current paper, the role of PKC δ was examined in fenretinide-induced apoptosis in lymphoid leukemia cells. Levels of proapoptotic cleaved PKC δ positively correlated with drug sensitivity. Fenretinide promoted reactive oxygen species (ROS) generation. The antioxidant Vitamin C prevented fenretinide-induced PKC δ cleavage and protected cells from fenretinide. Suppression of PKC δ expression by shRNA sensitized cells to fenretinide-induced apoptosis possibly by a mechanism involving ROS production. A previous study demonstrated that fenretinide promotes degradation of antiapoptotic MCL-1 in ALL cells via JNK. Now we have found that fenretinide-induced MCL-1 degradation may involve PKC δ as cleavage of the kinase correlated with loss of MCL-1 even in cells when JNK was not activated. These results suggest that PKC δ may play a complex role in fenretinide-induced apoptosis and may be targeted in antileukemia strategies that utilize fenretinide.

Nanoparticles for local drug delivery to the oral mucosa: proof of principle studies

Purpose

To determine if solid lipid nanoparticles represent a viable strategy for local delivery of poorly water soluble and unstable chemopreventive compounds to human oral tissues.

Methods

Nanoparticle uptake and compound retention evaluations employed monolayer-cultured human oral squamous cell carcinoma (OSCC) cell lines and normal human oral mucosal explants. Feasibility of nanoparticle delivery was also evaluated with respect to the presence of phase-III efflux transporters in normal oral mucosal tissue and OSCC tissues.

Results

Functional uptake assays confirmed significantly greater internalization of nanoparticle-delivered fluorescent probe relative to free-fluorescent probe delivery, while concurrently demonstrating nanoparticle uptake rate differences among the OSCC cell lines and the phagocytic control human monocyte cell line. Mucosal explants exhibited nanoparticle penetration and internalization in the spinous and basal epithelial layers (7/10 specimens), and also exhibited the presence of the phase-III efflux transporters multidrug resistance-associated protein 1 (MRP1) and breast cancer resistance protein (BCRP).

Conclusions

These data confirm nanoparticle internalization by OSCC cells and support the premise that nanoparticle-based delivery provides higher final intracellular levels relative to bolus administration. Furthermore, the penetration and subsequent internalization of nanoparticles within the proliferating basal layer cells demonstrates the feasibility of nanoparticle formulations for local delivery and stabilization of oral chemopreventive compounds.

Fenretinide induces mitochondrial ROS and inhibits the mitochondrial respiratory chain in neuroblastoma

Fenretinide induces apoptosis in neuroblastoma by induction of reactive oxygen species (ROS). In this study, we investigated the role of mitochondria in fenretinide-induced cytotoxicity and ROS production in six neuroblastoma cell lines. ROS induction by fenretinide was of mitochondrial origin, demonstrated by detection of superoxide with MitoSOX, the scavenging effect of the mitochondrial antioxidant MitoQ and reduced ROS production in cells without a functional mitochondrial respiratory chain (Rho zero cells). In digitonin-permeabilized cells, a fenretinide concentration-dependent decrease in ATP synthesis and substrate oxidation was observed, reflecting inhibition of the mitochondrial respiratory chain. However, inhibition of the mitochondrial respiratory chain was not required for ROS production. Co-incubation of fenretinide with inhibitors of different complexes of the respiratory chain suggested that fenretinide-induced ROS production occurred via complex II. The cytotoxicity of fenretinide was exerted through the generation of mitochondrial ROS and, at higher concentrations, also through inhibition of the mitochondrial respiratory chain.

Control of oxidative phosphorylation by vitamin A illuminates a fundamental role in mitochondrial energy homoeostasis

The physiology of two metabolites of vitamin A is understood in substantial detail: retinaldehyde functions as the universal chromophore in the vertebrate and invertebrate eye; retinoic acid regulates a set of vertebrate transcription factors, the retinoic acid receptor superfamily. The third member of this retinoid triumvirate is retinol. While functioning as the precursor of retinaldehyde and retinoic acid, a growing body of evidence suggests a far more fundamental role for retinol in signal transduction. Here we show that retinol is essential for the metabolic fitness of mitochondria. When cells were deprived of retinol, respiration and ATP synthesis defaulted to basal levels. They recovered to significantly higher energy output as soon as retinol was restored to physiological concentration, without the need for metabolic conversion to other retinoids. Retinol emerged as an essential cofactor of protein kinase Cdelta (PKCdelta), without which this enzyme failed to be activated in mitochondria. Furthermore, retinol needed to physically bind PKCdelta, because mutation of the retinol binding site rendered PKCdelta unresponsive to Rol, while retaining responsiveness to phorbol ester. The PKCdelta/retinol complex signaled the pyruvate dehydrogenase complex for enhanced flux of pyruvate into the Krebs cycle. The baseline response was reduced in vitamin A-deficient lecithin:retinol acyl transferase-knockout mice, but this was corrected within 3 h by intraperitoneal injection of vitamin A; this suggests that vitamin A is physiologically important. These results illuminate a hitherto unsuspected role of vitamin A in mitochondrial bioenergetics of mammals, acting as a nutritional sensor. As such, retinol is of fundamental importance for energy homeostasis. The data provide a mechanistic explanation to the nearly 100-yr-old question of why vitamin A deficiency causes so many pathologies that are independent of retinoic acid action.

The effects of HIF-1alpha on gene expression profiles of NCI-H446 human small cell lung cancer cells

BACKGROUND

Gene targeted therapy refers to any therapy focused on one of the many biological features of the tumor. Such features are mediated by specific genes that are involved in tumor metastasis, recurrence, poor response to chemotherapy and others. Hypoxia is an important pathognomonic feature of many malignant tumors including SCLC (small cell lung cancer). HIF-1alpha, which is induced by hypoxia, is the most important regulatory factor of many specific genes that can influence the biological features of tumors.

METHODS

In this study, we tried to elucidate the changes in gene expression profiles of SCLC NCI-H446 cells mediated by HIF-1alpha. According to different treatments of cells, three experimental pairwise comparisons were designed: hypoxia group vs. control group, Ad5-HIF-1alpha group vs. Ad5 group, and Ad5-siHIF-1 alpha group Vs Ad5 group.

RESULTS

Results from the analysis of gene expression profiles indicated that there were 65 genes upregulated and 28 genes downregulated more than two-fold in all three experimental pairwise comparisons. These genes were involved in transport, signal-transduction, cell adhesion/motility, growth factor/cytokines, transcription, inflammatory response, metabolic process, in addition to others. SOCS1, IGFBP5, IL-6 and STAT3 were also upregulated at protein level. SOCS1 could significantly induce apoptosis and suppress growth of NCI-H446 cells but HIF-1alpha could induce growth and suppress apoptosis.

CONCLUSIONS

Through this research, we are trying to find novel functional genes that are mediated by HIF-1alpha and provide the theoretical basis for new therapeutic targets. HIF-1 alpha maybe upregulate the expression of SOCS1 through mediation of STAT3 and IL-6. In addition, SOCS1 could significantly induce apoptosis and suppress growth of NCI-H446 cells. This was contrary to HIF-1alpha and it indicated that there might be an antagonism effect between HIF-1alpha and SOCS1 on regulating growth and apoptosis of NCI-H446 cells.

Induction and intracellular localization of Nur77 dictate fenretinide-induced apoptosis of human liver cancer cells

Fenretinide, a synthetic retinoid, is known to induce apoptosis in various cancer cells. However, the mechanism by which fenretinide induces apoptosis remains unclear. The current study examines the mechanisms of fenretinide-induced apoptosis in human hepatoma cells. The induction of Nur77 and the cytoplasmic distribution of Nur77 induced by fenretinide were positively correlated with the apoptotic effect of fenretinide in HCC cells. The sensitivity of Huh-7 cells was related to Nur77 translocation and targeting mitochondria, whereas the mechanism of resistance for HepG2 cells seemed due to Nur77 accumulating in the nucleus. The intracellular location of Nur77 was also associated with the differential capability of fenretinide-induced ROS generation in these two cell lines. In addition, the knockdown of Nur77 expression by siRNA greatly reduced fenretinide-induced apoptosis and cleaved caspase 3 in Huh-7 cells. Therefore, our findings demonstrate that fenretinide-induced apoptosis of HCC cells is Nur77 dependent and that the intracellular localization of Nur77 dictates the sensitivity of the HCC cells to fenretinide-induced apoptosis.

Possible roles of a tumor suppressor gene PIG11 in hepatocarcinogenesis and As2O3-induced apoptosis in liver cancer cells

BACKGROUND

Our previous studies demonstrated that p53-induced gene 11 (PIG11) was involved in arsenic trioxide (As(2)O(3))-induced apoptosis in human gastric cancer MGC-803 cells. Here, we studied further PIG11 expression in human hepatocellular carcinoma (HCC) tissues and cell lines and compared the sensitivity to As(2)O(3)-induced cell apoptosis in HepG2 and L-02 cells.

METHODS

PIG11 expression in human normal liver tissues, HCC tissues, and cell lines was determined by immunohistochemistry and immunocytochemistry methods, using an anti-human PIG11 antibody. Cell viability was estimated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diplenyltetrazolium bromide (MTT) assay. Cell apoptosis was determined by flow cytometry. Reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blotting were performed to analyze PIG11 mRNA and protein expression in cells. Protein intensity was calculated by comparison with the intensity of beta-actin, using densitometry. PIG11 was knocked down using small interfering RNA (siRNA).

RESULTS

We found that PIG11 expression was significantly downregulated in HCC tissue and the cell lines (Bel-7402, SMMC-7721, HepG2 cells). Further, HepG2 cells were more sensitive to As(2)O(3)-induced apoptosis than L-02 cells. The expression of PIG11 mRNA and protein was upregulated to a greater extent in HepG2 than in L-02 cells. In the presence of actinomycin D or cycloheximide, the amount of PIG11 protein expression did not increase. Likewise, the inhibition of PIG11 by siRNA decreased As(2)O(3)-induced PIG11 protein expression by more than 85% and partially prevented As(2)O(3)-induced apoptosis in both HepG2 and L-02 cells.

CONCLUSION

The above results demonstrated that the PIG11 gene may be involved in As(2)O(3)-induced apoptosis in HepG2 cells and suggested that the adaptive response of PIG11 expression is one of the important factors in enhancing cell sensitivity to As(2)O(3)-induced apoptosis.

Benzyl isothiocyanate-mediated generation of reactive oxygen species causes cell cycle arrest and induces apoptosis via activation of MAPK in human pancreatic cancer cells

In our previous studies, we have shown that benzyl isothiocyanate (BITC) inhibits the growth of human pancreatic cancer cells by inducing apoptosis. In the present study, we demonstrate the activation of all the three (MAPK) family members [extracellular signal-regulated protein kinase (ERK), c-jun N-terminal kinase (JNK) and P38] in response to BITC treatment. Exposure of Capan-2 cells with varying concentrations of BITC for 24 h resulted in the phosphorylation (activation) of ERK at Thr202/Tyr204, JNK at Thr183/Tyr185 and P38 at Thr180/Tyr182, leading to the induction of apoptosis. Similar MAPK activation was also observed in MiaPaCa-2 cells in response to BITC treatment. However, normal human pancreatic ductal epithelial cells did not show the activation of MAPK's and remained unaffected by BITC treatment. To confirm the role of ERK, JNK and P38 in BITC-induced G(2)/M arrest and apoptosis, Capan-2 cells were pre-treated with MAPK-specific inhibitors or MAPK8-short hairpin RNA (shRNA) prior to BITC treatment. Significant protection from BITC-induced G(2)/M arrest was observed in the cells pre-treated with MAPK kinase (MEK-1) but not JNK or P38 inhibitors. On the other hand, BITC-induced apoptosis was almost completely abrogated in the cells pre-treated with MEK-1, JNK or P38 inhibitors. Similarly, MAPK8-shRNA also offered almost complete protection against BITC-induced G(2)/M arrest and apoptosis. Furthermore, we observed that BITC treatment leads to the generation of reactive oxygen species (ROS) in Capan-2 and MiaPaCa-2 cells, which in part was orchestrated by depletion of reduced glutathione (GSH) level. Blocking ROS generation with N-acetyl-L-cysteine (NAC) significantly prevented GSH depletion and activation of ERK and JNK but not P38. Further, NAC or tiron prevented G(2)/M arrest by blocking G(2)/M regulatory proteins and completely protected the cells from BITC-induced apoptosis. Taken together, our results suggest that BITC-mediated G(2)/M arrest is mediated through ERK activation, whereas apoptosis is via ERK, JNK and P38.

Fenretinide inhibits myeloma cell growth, osteoclastogenesis and osteoclast viability

Fenretinide (4HPR), a nontoxic analog of ATRA, has been investigated in various malignancies but not in multiple myeloma (MM), a plasma cell malignancy associated with induction of osteolytic bone disease. Here we show that 4HPR induces apoptosis through increased level of ROS and activation of caspase-8, 9 and 3, and inhibits growth of several MM cell lines in a dose-dependent manner. Serum or co-culture with the supportive osteoclasts partially protects MM cells from 4HPR-induced growth inhibition. Sphingosine-1 phosphate (S1P) significantly protects MM cells from 4HPR-induced apoptosis suggesting that as in other malignancies, this drug up-regulates ceramide in MM cells. 4HPR has no toxic effects on non-malignant cells such as blood mononucleated cells, mesenchymal stem cells and osteoblasts, but markedly reduces viability of endothelial cells and mature osteoclasts and inhibits differentiation of osteoclasts and MM-induced tube formation. 4HPR is a potential anti-MM agent, affecting MM cells and MM-induced bone disease and angiogenesis.

PLAB induction in fenretinide-induced apoptosis of ovarian cancer cells occurs via a ROS-dependent mechanism involving ER stress and JNK activation

Fenretinide [N-(4-hydroxyphenyl)-retinamide (4HPR)] is a synthetic retinoid with antitumor activity that induces apoptosis in various types of cancer cell. We showed previously that 4HPR upregulates the proapoptotic gene placental bone morphogenetic protein (PLAB), which is a mediator of 4HPR-induced apoptosis in ovarian cancer cells. Here, we investigated the signaling cascade involving PLAB that mediates the apoptotic effect. In 4HPR-sensitive ovarian cancer cells, 4HPR-induced reactive oxygen species (ROS) are involved in PLAB upregulation and apoptosis, both events abrogated by the antioxidants vitamin C and butylated hydroxyanisole. We analyzed the expression and activation of endoplasmic reticulum (ER) stress-associated molecules and show that 4HPR-induced ER stress is a consequence of ROS generation. Salubrinal, an ER stress inhibitor, abrogated 4HPR-induced PLAB upregulation and protected the cells from apoptosis. Downstream of ROS generation and ER stress, 4HPR activated c-Jun N-terminal kinase (JNK), which was inhibited by vitamin C and salubrinal. The JNK inhibitor SP600125 reduced 4HPR-induced PLAB upregulation, by decreasing PLAB mRNA half-life, and protected the cells from apoptosis. These data indicate that 4HPR-induced PLAB upregulation occurs downstream of a signaling cascade involving ROS generation, ER stress induction and JNK activation and that these steps are mediators of 4HPR-induced apoptosis.