Alterations In Signal Transduction Pathways Research Articles

Abstract B106: Antibody-drug conjugates targeted at human aspartyl (asparaginyl) β-hydroxylase

Abstract Antibody-drug conjugates (ADCs) consist of an antibody that is specific for a disease antigen linked to one or more drug molecules. The goal is to utilize the antibody as a means of specific delivery of the drug to diseased cells. Theoretically this should decrease systemic exposure to the drug and allow for use of a lower dose. In cancer, the approach employs an antibody targeted at a tumor-associated antigen and a cytotoxic or cytostatic drug. To date there have been three ADCs approved by the US FDA for cancer treatment, and many more are now in the development stage. The efficacy of any ADC is dependent on three factors: the antibody, the attached drug, and the linker used to connect them. While each of these factors is of import, with the growth of interest in ADCs for cancer therapy, the use of specific drugs and linkers has become more routine. Thus, the specificities of the antibody and target antigen are now perhaps the primary obstacles towards the development of novel ADCs. Human aspartyl (asparaginyl) β-hydroxylase (HAAH) is an embryonic/developmental protein, which is downregulated in normal cells after birth but overexpressed on the surface of many malignant cells. It has been demonstrated to be sufficient to induce cancer cell proliferation, motility, and invasiveness. The enzyme hydroxylates important residues in the NOTCH protein altering signal transduction pathways that lead to increased growth and metastatic potential. Increased levels of HAAH have been detected by immunohistochemistry in a diverse array of solid and hematologic cancers (n > 20), including liver, bile duct, brain, breast, colon, prostate, ovary, pancreas, and lung cancers as well as various leukemias. HAAH is not found in measurable quantities in normal tissue (n > 500), including normal adjacent tissue within cancer biopsy specimens or in benign proliferative disorders. We have developed a fully human antibody against HAAH, PAN-622,that displays exquisite specificity for cancer. Here we explore PAN-622 drug conjugates for ultimate use in treating both hematologic and solid tumors. PAN-622 was conjugated to three different drugs: a maytansinoid (DM1), monomethyl auristatin E (MMAE), and duocarmycin (DUO). DM1 was conjugated via a noncleavable thio-ether linker while MMAE and DUO were conjugated using valine-citruline containing linkers that are cleavable by cathepsin B in the endosomal compartment. Conjugation of drugs to the PAN-622 antibody had little effect on the affinity of the antibody for HAAH. Binding affinities were determined by immunoassay on fixed cancer cells (H460, human lung cancer line) and were ~0.1, 0.2, and 0.5nM for PAN-622-DM1, PAN-622-MMAE, and PAN-622-DUO, respectively. The affinity of PAN-622 for HAAH as expressed on live cells has previously been shown to be ~1nM. Efficacies of the three ADCs for killing of H460 cells were determined using an MTS assay. The PAN-622-DM1 had an EC50 of ~15nM. The EC50 for PAN-622-MMAE was ~60nM, and that for PAN-622-DUO was ~300nM. Importantly, both unconjugated PAN-622 and a nonrelevant antibody conjugated to MMAE did not display any killing of the H460 cell line. Efficacy was also measured on a representative hematologic cancer line, MOLM-14 (acute myelogenous leukemia) where EC50s were in the 20-50nM range for all three ADCs. This work serves as a proof of concept, laying the groundwork for further development of HAAH-targeted ADCs. Citation Format: Kanam Malhotra, Susan Walker, Chen Fang, Karamveer Birthare, Michael S. Lebowitz, Steven Fuller, Muctarr Sesay, Hossein A. Ghanbari. Antibody-drug conjugates targeted at human aspartyl (asparaginyl) β-hydroxylase [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B106.

Nutrition composition differences among steamed and freeze-dried mature silkworm larval powders made from 3 Bombyx mori varieties weaving different colored cocoons

The mulberry silkworm, Bombyx mori has been one of the most important domestic animals which have provided with silk fibers for weaving fabrics and a food for a protein and lipid source. In addition, various health improvement effects of diverse silkworm larval powders were reported. Recently we found that steamed and freeze-dried mature silkworm larval powder (SMSP) generated using white-jade (also known as Backokjam) silkworm variety extended healthspan and increased resistance to Parkinson`s disease in animal models. Because the colors of cocoons in silkworm varieties were caused by altered signal transduction pathways transporting phytochemicals from intestinal lumens to silk glands, we performed the proximate, amino acid, mineral, carbohydrates, fatty acid, and cholesterol composition analyses of SMSPs of 3 silkworm varieties which were weaving light yellow, golden, and red cocoons. Although most of nutrient compositions among 3 SMSPs were similar, there were significant differences in certain amino acids, minerals, and fatty acid compositions. Red silk silkworm (RS)-SMSP had higher contents of crude proteins and total amino acids than other SMSPs. In addition, the ratio of n-3/ n-6 unsaturated fatty acids were higher than the other SMSPs. In contrast Golden silk silkworm (GS)-SMSP had higher ratio of potassium/sodium than the other SMSPs. These nutrient analysis results suggested that 3 SMSPs might have common and unique health improvement effects. Thus, further studies in the functionalities of the 3 SMSPs will reveal unknown their health improvements effects.

The Role of Gammaherpesviruses in Cancer Pathogenesis.

Worldwide, one fifth of cancers in the population are associated with viral infections. Among them, gammaherpesvirus, specifically HHV4 (EBV) and HHV8 (KSHV), are two oncogenic viral agents associated with a large number of human malignancies. In this review, we summarize the current understanding of the molecular mechanisms related to EBV and KSHV infection and their ability to induce cellular transformation. We describe their strategies for manipulating major cellular systems through the utilization of cell cycle, apoptosis, immune modulation, epigenetic modification, and altered signal transduction pathways, including NF-kB, Notch, Wnt, MAPK, TLR, etc. We also discuss the important EBV latent antigens, namely EBNA1, EBNA2, EBNA3’s and LMP’s, which are important for targeting these major cellular pathways. KSHV infection progresses through the engagement of the activities of the major latent proteins LANA, v-FLIP and v-Cyclin, and the lytic replication and transcription activator (RTA). This review is a current, comprehensive approach that describes an in-depth understanding of gammaherpes viral encoded gene manipulation of the host system through targeting important biological processes in viral-associated cancers.

Latent class analysis of bladder urothelial carcinoma to reveal sub-classes defined by alterations to chromatin and signal transduction networks.

469 Background: 70,000 new cases of bladder urothelial carcinoma are diagnosed in the United States each year. Previous studies of this disease suggest two divergent pathways of carcinogenesis, with ~70% of cases being driven by alterations in signal transduction pathways (FGFR3, HRAS) and the remainder featuring alterations in cell cycle genes (TP53, RB1). Other studies focus on the high prevalence of alterations in chromatin remodeling genes (ARID1A, CREBBP, EP300) in this tumor type. The relationship between chromatin modifier alterations and the two bladder TCC sub-classes is not yet understood. Methods: Comprehensive genomic profiling (CGP) on 638 clinically confirmed cases of advanced bladder urothelial carcinoma was performed using the FoundationOne platform. The coding exons of 287 cancer-related and 47 introns of 19 genes frequently rearranged in cancer were sequenced and analyzed for base substitutions, insertions, deletions, copy number alterations and select gene fusions. The resultant alteration profiles were analyzed for their information content with an entropy-based approach and the profiles were subjected to hierarchical latent class analysis (LCA). Results: CGP of 488 male and 150 female UCs of median age 66 (min: 29, max: 87) resulted in 3241 detected alterations across 302 unique genes, for a mean of ~5.1 known or likely somatic alterations per sample. The most commonly altered genes were TP53, CDKN2A/B, ARID1A, KDM6A, and MLL2. Information was concentrated in the 33 most frequently altered genes. Multiple high level clusters were defined by combinatorial patterns of alterations in TP53, CDKN2A/B, RB1, and FGFR3. Sub-classes were defined by mutually exclusive alterations in the chromatin modifiers KDM6A, MLL2, and ARID1A. Conclusions: We present a global picture of UC sub-classes that encompasses previously identified local relationships including the mutual exclusivities between FGFR3 and TP53, RB1 and CDKN2A/B, and KDM6A and MLL2. In the context of clinically relevant genomic alterations that auger response to targeted therapies, identification of sub-classes of UC may further delineate response to therapy.

Anti-Oxidant, Pro-Oxidant and Anti-Inflammatory Effects of Unpolished Rice Relevant to Colorectal Cancer

Colorectal cancer (CRC) is a major worldwide health problem owing to its high prevalence and mortality rates. Carcinogenesis in the colon is a multistage and multifactorial process. An imbalance between free radical exposure and anti-oxidant defense systems may leads to oxidative stress and attack of macromolecules which can alter signal transduction pathways and gene expression. Consequently, oxidative damage can lead to cellular dysfunction and contribute to pathophysiological processes in a variety of diseases including CRC. One factor tightly associated with CRC is chronic inflammation, which can be present from the earliest stage of tumor onset. Unpolished rice is an attractive chemoprevention in CRC due to their anti-oxidant and anti-inflammatory activities. The aim of this paper is to review evidence linking oxidative stress and inflammation to CRC and to provide essential background information for understanding future research on oxidative stress and inflammation on CRC. Mechanisms of action of unpolished rice in CRC carcinogenesis are also discussed.

Deletion of WISP1 leads to higher sensitivity to carbon tetrachloride-induced liver damage

WISP1 (Wnt-induced secreted protein-1) is a member of the CCN family of matricellular proteins. These highly conserved and secreted proteins can interact with integrins and modulate many biological processes like migration, proliferation, differentiation and apoptosis. CCN proteins have been show to play divergent roles in liver pathophysiology, in spite of having very similar structural domains. Importantly, little is known about WISP1 in this context. Gene array analysis of mouse liver after acute injury by intraperitoneal injection of CCl4 in C56BL/6N mice showed WISP1 mRNA upregulated during early injury phase, between 2h and 24h after CCl4 injection. These results were confirmed by real time PCR, showing a maximal induction of 40 fold over healthy liver at 24h. To establish the role of WISP1 in acute liver damage we used a knockout mouse model, in which WISP1 expression is disrupted by replacing Exon 2 with a resistance cassette and a stop codon. Heterozygous mice were bred to establish homozygous knockout and wild type lines which were validated by genotyping. Real time PCR analysis confirmed the absence of WISP1 mRNA expression in KO mice challenged with CCl4. Remarkably, deletion of WISP1 led to a significant increase of necrotic area at 24h. This was show by hematoxylin & eosin staining reaching 49% in KO vs. 27% in WT mice (p < 0.0001; n = 13 wild type, n = 11 KO) and serum transaminase activity (GPT: 8230 U/l in WT, 12300 U/l in KO). Importantly, immunofluorescence and real time PCR showed that WT and WISP1 KO mice have no significant differences in CYP2E1 expression, suggesting that the difference in tissue injury does not depend on alterations of CCl4 metabolism in KO mice. To further characterize this different phenotype, we performed a time course after CCl4 intoxication (460 mg/kg, i.p.) by collecting liver tissue at 30 min, 2h, 8h, 18h, and 24h. Interestingly, already at 18h KO mice showed a clear necrotic area around the central veins whereas WT mice showed ballooned hepatocytes with cytoplasmic translocation of high-mobility group protein B1 (HGMB1), indicating that WISP1 KO mice had a more advanced stage of liver injury at this time point than the WT counterparts. This phenotype was also observed upon intoxication with lower doses of CCl4 (132.4 mg/kg and 76 mg/kg). Analysis of cytokine expression by real time PCR showed a stronger induction of TNFα in WISP1 KO mice (7-fold v/s 10-fold at 18h, and 3-fold vs. 6-fold at 24h in WT vs. WISP1 KO respectively), and IL6 (5-fold vs. 10-fold at 18h, and no induction vs. 3-fold at 24h in WT v/s WISP1 KO respectively). Furthermore, western blot analysis showed marked alterations in signal transduction pathways in liver tissue of WISP1 KO mice, with stronger activations of p-JNK at 2h and p-STAT3 at 18h and 24h. Currently we are investigating the mechanism through which WISP1 exerts a protective role upon CCl4 stimulation in liver damage and in the subsequent regeneration process. In conclusion we have strong evidence that WISP1 plays an important role in acute liver damage.

Mechanisms of Photoaging and Cutaneous Photocarcinogenesis, and Photoprotective Strategies with Phytochemicals.

Photoaging and photocarcinogenesis are primarily due to solar ultraviolet (UV) radiation, which alters DNA, cellular antioxidant balance, signal transduction pathways, immunology, and the extracellular matrix (ECM). The DNA alterations include UV radiation induced thymine-thymine dimers and loss of tumor suppressor gene p53. UV radiation reduces cellular antioxidant status by generating reactive oxygen species (ROS), and the resultant oxidative stress alters signal transduction pathways such as the mitogen-activated protein kinase (MAPK), the nuclear factor-kappa beta (NF-κB)/p65, the janus kinase (JAK), signal transduction and activation of transcription (STAT) and the nuclear factor erythroid 2-related factor 2 (Nrf2). UV radiation induces pro-inflammatory genes and causes immunosuppression by depleting the number and activity of the epidermal Langerhans cells. Further, UV radiation remodels the ECM by increasing matrixmetalloproteinases (MMP) and reducing structural collagen and elastin. The photoprotective strategies to prevent/treat photoaging and photocarcinogenesis include oral or topical agents that act as sunscreens or counteract the effects of UV radiation on DNA, cellular antioxidant balance, signal transduction pathways, immunology and the ECM. Many of these agents are phytochemical derivatives and include polyphenols and non-polyphenols. The flavonoids are polyphenols and include catechins, isoflavones, proanthocyanidins, and anthocyanins, whereas the non-flavonoids comprise mono phenolic acids and stilbenes. The natural sources of polyphenols include tea, cocoa, grape/wine, soy, pomegranate, and Polypodium leucotomos. The non-phenolic phytochemicals include carotenoids, caffeine and sulphoraphance (SFN). In addition, there are other phytochemical derivatives or whole extracts such as baicalin, flavangenol, raspberry extract, and Photomorphe umbellata with photoprotective activity against UVB radiation, and thereby carcinogenesis.

Accumulation of N-Acylphosphatidylserines and N-Acylserines in the Frontal Cortex in Schizophrenia.

While schizophrenia is generally considered a neurodevelopment disorder, our basic understanding of the biochemical processes involved in disease etiology and/or progression is limited. One class of biochemical mediators that has been suggested to play a role in the development of schizophrenia is N-acyl ethanolamine metabolites of N-acylphosphatidylethanolamines. However, no investigations of N-acylphosphatidylserines or their N-acylserine metabolites have been published. We undertook a targeted postmortem lipidomics analysis of N-acylphosphatidylserines (NAPS) and N-acylserines (NAS) in gray matter of the frontal cortex of schizophrenia subjects. Our data are the first to demonstrate that NAPS and NAS are present in human brain. Furthermore, NAPS and their bioactive metabolites, N-acylserines (NAS), were found to be significantly elevated in the frontal cortex of schizophrenia subjects. Elevated levels of NAPS lipid pools in schizophrenia may result in complex alterations in the structural function of neuronal membranes while increases in NAS may alter signal transduction pathways.

Significant cytostatic effect of everolimus on a gefitinib-resistant anaplastic thyroid cancer cell line harboring PI3KCA gene mutation.

We previously demonstrated the efficacy of gefitinib, a tyrosine kinase inhibitor of the epidermal growth factor receptor (EGFR), on an anaplastic thyroid cancer (ATC) cell line. We also observed that gefitinib was not effective in regulating cell growth in a different ATC cell line that exhibited an altered EGFR-initiated signal transduction pathway. In the present study, we attempted to regulate the downstream effector of EGFR-Akt-mammalian target of rapamycin (mTOR) pathway by an mTOR inhibitor, everolimus. A total of 8 ATC cell lines were employed, 7 of which were established in our institute. OCUT-2 was known to carry a mutation in the phosphoinositide-3-kinase, catalytic, α polypeptide gene (PI3KCA) and to be gefitinib-resistant, whereas ACT-1 exhibited a remarkable growth arrest by gefitinib. All the cell lines were tested for the cytotoxic effect of everolimus. The mechanisms of cellular toxicity were investigated by EGFR stimulation, cell cycle and concurrent exposure to paclitaxel. In OCUT-2, but not in any of the other cell lines, everolimus achieved a significant growth inhibition (inhibition of 30 and 50% was achieved by concentrations of 0.8 and 5 nM, respectively). The growth in OCUT-2 was inhibited by everolimus, even with concordant EGFR stimulation. This effect was demonstrated by a G2M cell cycle arrest. An additive effect of everolimus onto the cytotoxic effect of paclitaxel was demonstrated at a dose of 1-2 nM. A significant growth inhibitory effect of everolimus on the gefitinib-resistant ATC cell line was demonstrated, suggesting a possible correlation between the efficacy of everolimus and PI3KCA gene mutation and the significance of molecular-targeted therapy in the management of ATC.

Decreased Expression Levels of Tumor Suppressor MicroRNAs in Hairy Cell Leukemia

Hairy cell leukemia is a chronic, clonal disease of the hemopoetic stem cell. Although our knowledge on its pathogenesis has increased a lot during the previous years, further details are needed to provide a more personalized, and therefore more successful treatment for patients. New advancements in the growing field of epigenetics may contribute to the finding of novel therapeutic target molecules. Similarly to acute leukemia, hairy cell leukemia also possesses a unique microRNA expression pattern. Decreased levels of tumor suppressor microRNAs lead to the elevation of the expression levels of their oncogenic targets. During our investigations on the level of let-7b and miR-124 in the bone marrow sample of a patient suffering from hairy cell leukemia, decreased expression levels have been found in the case of both microRNAs. These alterations also influence the activity of the MAPK signaling pathway, resulting from the regulation of its members by microRNAs including those mentioned above. Our results support new details about the connection between altered microRNA expression levels and signal transduction pathways in hairy cell leukemia.

Multifaceted effects of oligodendroglial exosomes on neurons: impact on neuronal firing rate, signal transduction and gene regulation.

Exosomes are small membranous vesicles of endocytic origin that are released by almost every cell type. They exert versatile functions in intercellular communication important for many physiological and pathological processes. Recently, exosomes attracted interest with regard to their role in cell-cell communication in the nervous system. We have shown that exosomes released from oligodendrocytes upon stimulation with the neurotransmitter glutamate are internalized by neurons and enhance the neuronal stress tolerance. Here, we demonstrate that oligodendroglial exosomes also promote neuronal survival during oxygen-glucose deprivation, a model of cerebral ischaemia. We show the transfer from oligodendrocytes to neurons of superoxide dismutase and catalase, enzymes which are known to help cells to resist oxidative stress. Additionally, we identify various effects of oligodendroglial exosomes on neuronal physiology. Electrophysiological analysis using in vitro multi-electrode arrays revealed an increased firing rate of neurons exposed to oligodendroglial exosomes. Moreover, gene expression analysis and phosphorylation arrays uncovered differentially expressed genes and altered signal transduction pathways in neurons after exosome treatment. Our study thus provides new insight into the broad spectrum of action of oligodendroglial exosomes and their effects on neuronal physiology. The exchange of extracellular vesicles between neural cells may exhibit remarkable potential to impact brain performance.

Wnt meets Warburg: another piece in the puzzle?

One of the most common abnormalities of cancer cells is their predilection to engage in a high rate of glycolysis despite the continued availability of oxygen. First described by Otto Warburg, this phenomenon of aerobic glycolysis (or the Warburg effect) has recently been proposed to result from cancer‐associated alterations in signal transduction pathways. In this issue of The EMBO Journal, Pate et al provide further support for this hypothesis by demonstrating that Wnt signaling plays an important role in establishing aerobic glycolysis as a mechanism to support in vivo cancer cell proliferation.

Neuron-Specific Alterations in Signal Transduction Pathways associated with Alzheimer's Disease

The hallmarks of sporadic Alzheimer's disease (AD) are extracellular amyloid deposits, intracellular neurofibrillary tangles (NFTs), and neuronal death. Hyperphosphorylation of tau is a key factor in the generation of NFTs. Mitogen activated protein kinase 1 (MAPK1) and protein kinase C beta (PRKCB) are thought to play a role in hyperphosphorylation, and PRCKB is thought to be involved in hypoxic stress and vascular dysfunction, and to trigger MAPK phosphorylation pathways. We performed single-cell analyses of neurons with different vulnerabilities to AD-related changes. Using quantitative PCR (qPCR), we measured the levels of MAPK1 and PRKCB transcript in CA1 (high vulnerability), CA2 pyramidal cells from the hippocampus, granule cells from the cerebellum (low vulnerability), and neurons from the brain stem (nucleus tractus spinalis nervi trigemini, characterized by early neurophysiological deficits) at progressive Braak stages compared to age-matched controls. The highly vulnerable CA1 pyramidal neurons were characterized by age- and disease-unrelated increases in PRCKB levels and by age- and disease-related increases in MAPK1 levels. In contrast, low PRKCB levels were found in CA2 pyramidal neurons, and MAPK1 levels were elevated in controls and intermediate AD stages. Both PRKCB and MAPK1 were increased in the late AD stages. MAPK1 and PRKCB levels were low in the brainstem and cerebellum. We propose that alterations in the expression of these two genes occur early in the pathogenesis of AD in a region-specific manner. In addition, multiple signal transduction pathways need to be affected to result in AD instead of physiological aging.

Protective effects elicited by levosimendan against liver ischemia/reperfusion injury in anesthetized rats

As in other organs, oxidative stress-induced injury and cell death may result from free oxygen radical-dependent mechanisms and alterations in signal transduction pathways leading to apoptosis. Among the new suggested therapies for injuries caused by oxidative stress, the use of levosimendan has been reported to be quite promising. In the present study, we aimed to examine the protective effects of levosimendan against liver oxidative stress in anesthetized rats and to analyze the involvement of mitochondrial adenosine triphosphate-dependent potassium (mitoK(ATP)) channels and nitric oxide (NO). In 50 anesthetized rats, liver ischemia/reperfusion (I/R) was performed via nontraumatic portal occlusion. In some animals, levosimendan was infused into the portal vein at the onset of reperfusion, whereas other rats received the vehicle only. Moreover, in some rats, levosimendan was given after the intraportal administration of L-Nω-nitro-arginine methyl ester (L-NAME) or 5-hydroxydecanoate (5HD). The portal vein blood flow was measured, and blood samples were taken for the determination of transaminases, thiobarbituric acid reactive substances (TBARS), and reduced glutathione (GSH); liver biopsy samples were used for B cell lymphoma 2-associated X protein, caspase-9, Akt, and endothelial nitric oxide synthase (eNOS) activation through western blotting. Also, caspase-3 activity was measured. In rats, I/R caused an increase in apoptotic markers, transaminases, and TBARS and a decrease in GSH and Akt activation. Levosimendan administration was able to counteract oxidative damage and apoptosis in a dose-dependent way and to increase GSH, Akt, and eNOS activation. All effects of levosimendan were abolished by pretreatment with L-NAME and 5HD. In conclusion, the results of the present study show that levosimendan can exert protection against ischemic liver damage through mechanisms related to NO production and mitoKATP channel function. These data provide interesting perspectives into the use of levosimendan in hepatic surgery and transplantation.

Hedgehog-Dependent Regulation of Angiogenesis and Myogenesis Is Impaired in Aged Mice

The purpose of this study is to further document alteration of signal transduction pathways, more particularly of hedgehog (Hh) signaling, causing impaired ischemic muscle repair in old mice. We used 12-week-old (young mice) and 20- to 24-month-old C57BL/6 mice (old mice) to investigate the activity of Hh signaling in the setting of hindlimb ischemia-induced angiogenesis and skeletal muscle repair. In this model, delayed ischemic muscle repair observed in old mice was associated with an impaired upregulation of Gli1. Sonic Hh expression was not different in old mice compared with young mice, whereas desert Hh (Dhh) expression was downregulated in the skeletal muscle of old mice both in healthy and ischemic conditions. The rescue of Dhh expression by gene therapy in old mice promoted ischemia-induced angiogenesis and increased nerve density; nevertheless, it failed to promote myogenesis or to increase Gli1 mRNA expression. After further investigation, we found that, in addition to Dhh, smoothened expression was significantly downregulated in old mice. We used smoothened haploinsufficient mice to demonstrate that smoothened knockdown by 50% is sufficient to impair activation of Hh signaling and ischemia-induced muscle repair. The present study demonstrates that Hh signaling is impaired in aged mice because of Dhh and smoothened downregulation. Moreover, it shows that hegdehog-dependent regulation of angiogenesis and myogenesis involves distinct mechanisms.

Caffeic acid regulates LPS-induced NF-κB activation through NIK/IKK and c-Src/ERK signaling pathways in endothelial cells

The redox sensitive, proinflammatory nuclear transcription factor NF-κB plays a key role in inflammation. In a redox state disrupted by oxidative stress, pro-inflammatory genes are upregulated by the activation of NF-κB via diverse kinases. Thus, the search and characterization of new substances that modulate NF-κB are topics of considerable research interest. Caffeic acid is a component of garlic, some fruits, and coffee, and is widely used as a phenolic agent in beverages. In the present study, caffeic acid was examined with respect to the modulation of inflammatory NF-κB activation via the redox-related c-Src/ERK and NIK/IKK pathways via the reduction of oxidative stress. YPEN-1 cells (an endothelial cell line) were used to explore the molecular mechanism underlying the anti-inflammatory effect of caffeic acid by examining its modulation of NF-κB signaling pathway by LPS. Our results show that LPS-induced oxidative stress-related NF-κB activation upregulated pro-inflammatory COX-2, NF-κB targeting gene which were all inhibited effectively by caffeic acid. Our study shows that caffeic acid inhibits the activation of NF-κB via the c-Src/ERK and NIK/IKK signal transduction pathways. Our results indicate that antioxidative effect of caffeic acid and its restoration of redox balance are responsible for its anti-inflammatory action. Thus, the study provides new information regarding the anti-inflammatory properties of caffeic acid and the roles in the regulation of LPS-induced oxidative stress induces alterations in signal transduction pathways.

Inorganic Phosphate as a Signaling Molecule: A Potential Strategy in Osteosarcoma Treatment

Inorganic phosphate (Pi) is an essential nutrient to living organisms. It plays a key role in diverse biological processes, including osteoblast differentiation and skeletal mineralization. Maintenance of proper Pi homeostasis is a critical event, as any deviation from that state can lead to several acute and chronic disease states and influence the ageing process and lifespan. Serum Pi level is maintained within a narrow range through a complex interplay between intestinal absorption, exchange with intracellular and bone storage pools, renal tubular reabsorption and depends mainly on the activity of Na/Pi cotransporters. Pi is abundant in the diet and intestinal absorption of Pi is efficient and minimally regulated. The kidney is a major regulator of Pi homeostasis and can increase or decrease its Pi reabsorptive capacity to accommodate Pi need. Relevantly, Pi is emerging as an important signalling molecule capable of modulating multiple cellular functions by altering signal transduction pathways, gene expression and protein abundance in many cell types. However, little is known about the initial events involving the detection of changes in serum or local Pi concentrations and the subsequent downstream regulation cascade. Previously, we provided evidence that Pi inhibits proliferation and aggressiveness of human osteosarcoma U2OS cells identifying adenylate cyclase, beta3 integrin, Rap1, ERK1/2 as proteins whose expression and function are relevantly affected in response to Pi. More recently, we demonstrated that Pi is capable also of inducing sensitization of osteosarcoma cells to doxorubicin in a p53-dependent manner and through a mechanism involving ERK1/2 down-regulation. This review summarizes the current knowledge regarding inorganic phosphate as a novel specific signaling molecule in bone and other cell types in mammals and discuss how targeting Pi levels at local sites might represent a potential strategy for improving osteosarcoma therapy.

Bioactive Peptides in Cancer: Therapeutic Use and Delivery Strategies

Bioactive Peptides in Cancer: Therapeutic Use and Delivery Strategies

Synergistic cytotoxic effects of inorganic phosphate and chemotherapeutic drugs on human osteosarcoma cells

Novel therapeutic approaches are required for the treatment of osteosarcoma. Combination chemotherapy is receiving increased attention in order to identify compounds that may increase the therapeutic index of clinical anticancer drugs. In this regard, naturally occurring molecules with antitumor activity and with limited toxicity to normal tissues have been suggested as possible candidates for investigation of their synergistic efficacy in combination with antineoplastic drugs. Inorganic phosphate (Pi) is an essential nutrient for living organisms. Relevantly, Pi has emerged as an important signaling molecule capable of modulating multiple cellular functions by altering signal transduction pathways, gene expression and protein abundance in many cell types. Previously, we showed that Pi inhibits proliferation and aggressiveness of U2OS human osteosarcoma cells and that Pi is capable of inducing sensitization of osteosarcoma cells to doxorubicin in a p53-dependent manner. In this study, we extended the role of Pi in the chemosensitivity of osteosarcoma cells to other anticancer drugs. Specifically, we report and compare the antiproliferative effects of a combination between Pi and doxorubicin, Taxol® and 5-fluorouracil (5-FU) treatments. We found that Pi increases the antiproliferative response to both Taxol and doxorubicin to a similar extent. On the other hand, Pi did not potentiate the anticancer effects induced by 5-FU. These effects were paralleled by apoptosis induction and were cell cycle-dependent. The clinical significance of our data and their potential therapeutic applications for improving osteosarcoma treatment are discussed.

Inorganic Phosphate as a Novel Signaling Molecule with Antiproliferative Action in MDA-MB-231 Breast Cancer Cells

Inorganic phosphate (Pi) is an essential nutrient for living organisms. It plays a key role in diverse physiological functions, including osteoblast differentiation and skeletal mineralization. Relevantly, Pi is emerging as an important signaling molecule capable of modulating multiple cellular functions by altering signal transduction pathways, gene expression, and protein abundance in many cell types. To our knowledge, the consequences of elevated Pi on behavior of breast cancer cells have been poorly addressed. In this study we investigate the effects of Pi on proliferation of MDA-MB-231 breast cancer cells. We report that Pi inhibits proliferation of MDA-MB-231 cells by slowing cell cycle progression, without apoptosis occurrence. We found that Pi causes cells to accumulate in G1 phase in a time-dependent manner. Accordingly, G1 accumulation was associated with a decrease of cyclin A and cyclin E and an increase of cell cycle inhibitors p21 and p27 protein levels, respectively. Moreover, the Pi-induced antiproliferative effect was dynamically accompanied by profound changes in ERK1/2 and STAT3 protein and phosphorylation levels in response to Pi. Altogether, our data represent the first evidence of Pi acting as a novel signaling molecule in MDA-MB-231 breast cancer cells, capable of eliciting a strong antiproliferative action and suggest that targeting Pi levels at local sites might represent the rationale for developing novel strategies for therapeutic intervention in triple-negative breast cancer.