Interleukin-1β can mediate growth arrest and differentiation via the leukemia inhibitory factor/JAK/STAT pathway in medullary thyroid carcinoma cells

A Potential Nine-lncRNAs Signature Identification and Nomogram Diagnostic Model Establishment for Papillary Thyroid Cancer

The purpose of our current study was to establish a long non-coding RNA(lncRNA) signature and assess its prognostic and diagnostic power in papillary thyroid cancer (PTC). LncRNA expression profiles were obtained from the Cancer Genome Atlas (TCGA). The key module and hub lncRNAs related to PTC were determined by weighted gene co-expression network analysis (WGCNA) and LASSO Cox regression analyses, respectively. Functional enrichment analyses, including Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene set enrichment analysis were implemented to analyze the possible biological processes and signaling pathways of hub lncRNAs. Associations between key lncRNA expressions and tumor-infiltrating immune cells were identified using the TIMER website, and proportions of immune cells in high/low risk score groups were compared. Kaplan-Meier Plotter was used to evaluate the prognostic significance of hub genes in PTC. A diagnostic model was conducted with logistic regression analysis, and its diagnostic performance was assessed by calibration/receiver operating characteristic curves and principal component analysis. A nine-lncRNAs signature (SLC12A5-AS1, LINC02028, KIZ-AS1, LINC02019, LINC01877, LINC01444, LINC01176, LINC01290, and LINC00581) was established in PTC, which has significant diagnostic and prognostic power. Functional enrichment analyses elucidated the regulatory mechanism of the nine-lncRNAs signature in the development of PTC. This signature and expressions of nine hub lncRNAs were correlated with the distributions of tumor infiltrating immune cells. A diagnostic nomogram was also established for PTC. By comparing with the published models with less than or equal to nine lncRNAs, our signature showed a preferable performace for prognosis prediction. In conclusion, our present research established an innovative nine-lncRNAs signature and a six-lncRNAs nomogram that might act as a potential indicator for PTC prognosis and diagnosis, which could be conducive to the PTC treatment.

Molecular mechanisms of opioid tolerance: From opioid receptors to inflammatory mediators (Review)

Opioids are considered the most effective analgesics for the treatment of both acute and chronic pain. However, prolonged opioid use can induce a certain level of tolerance to its analgesic effects, leading to a reduction in its effectiveness, addiction and abuse. A better understanding of the mechanisms underlying opioid tolerance may provide insights into this phenomenon and aid in the development of novel methods to combat the side effects of opioid tolerance. The present review focused on two major contributors to tolerance, opioid receptors and inflammatory mediators. The molecular mechanisms involved in the desensitization of the opioid receptors were briefly described, including their phosphorylation, internalisation and recycling. Subsequently, the effects of Toll like receptor 4/NOD-like receptor family pyrin domain containing 3-mediated proinflammatory responses in opioid tolerance were discussed, aiming in supporting the identification of novel therapeutic targets.

STAT3 signaling statuses determine the fate of resveratrol-treated anaplastic thyroid cancer cells

BACKGROUNDS

Anaplastic thyroid cancer/ATC is highly lethal malignancy without reliable chemotherapeutic drug. Resveratrol possesses anti-ATC activities but encounters resistance in some cases due to certain unknown reason(s).

OBJECTIVE

Because signal transducer and activator of transcription/STAT3 signaling is critical for ATC cell survival and the main molecular target of resveratrol, its roles in determining the fates of resveratrol-treated ATC cells were investigated here.

METHODS

Human THJ-11T, THJ-16 and THJ-21T ATC cell lines were treated by 100 μM resveratrol and their growth, statuses of STAT3 signaling and STAT3-related gene expression were examined. The relevance of STAT3 activation with resveratrol resistance was elucidated using STAT selective inhibitor AG490. Leukemia inhibitory factor/LIF expression and phosphorylated-STAT3/p-STAT3 nuclear translocation in ATC tissues were immunohistochemically analyzed.

RESULTS

Resveratrol inhibited proliferation, p-STAT3 nuclear translocation as well as LIF and STAT3 expression of THJ-16T and THJ-21T but not THJ-21T cells which showed LIF upregulation and more frequent p-STAT3 nuclear translocation. AG490 significantly prevent p-STAT3 nuclear translocation, and reversed the resveratrol tolerance of THJ-11T cells. Immonohistochemical staining revealed 14.3% (4/28) of LIF and 3.6% (1/28) of p-STAT3 detection in noncancerous ATC-surrounding tissues, which increased to 89.5% (17/19) and 52.6% (10/19) respectively among ATC specimens. The correlative analysis indicated the relevance of LIF expression and STAT3 activation (r= 0.825; P< 0.01).

CONCLUSIONS

The status of STAT3 activation and LIF expression are closely correlated with the therapeutic effect of resveratrol on ATCs. Frequent LIF upregulation and STAT3 activation are the unfavorable factors of ATCs and the potential targets of anti-ATC therapy.

Circular RNA DOCK1 downregulates microRNA-124 to induce the growth of human thyroid cancer cell lines

BACKGROUND

Both circular RNA DOCK1 (circDOCK1) and microRNA-124 (miR-124) are implicated in carcinogenesis, but functional association between these two molecules remains uncharacterized. Here, we aimed to ascertain the role of circDOCK1-miR-124 node in thyroid cancer cells.

METHODS

circDOCK1 in thyroid cancer specimens from 25 patients was quantified by qRT-PCR. FTC-133 and TPC-1 cells were enforced to overproduce circDOCK1 and miR-124 which were confirmed by qRT-PCR. The alteration in viability, migration and invasion was monitored. Cellular lysis was subjected to Western blot for detecting cyclin D1, p53, matrix metallopeptidase 9 (MMP-9), and vimentin. The phosphorylation of JAK1, STAT3, and AMPK was determined by Western blot.

RESULTS

Results from qRT-PCR showed circDOCK1 was enriched in thyroid carcinoma tissues. circDOCK1 fortified the viability of FTC-133 and TPC-1 cells, as well as their activities to migrate and invade. circDOCK1 increased cyclin D1 and decreased p53, and meanwhile induced the accumulation of MMP-9 and vimentin. miR-124 conferred a reverse effect on the abovementioned alteration. Besides, miR-124 blockaded the phosphorylation of JAK1, STAT3, and AMPK which was induced by circDOCK1.

CONCLUSION

circDOCK1 contributed to thyroid carcinogenesis through inhibition of miR-124 in thyroid cancer cells with dampening signaling transduction of JAK/STAT/AMPK in virtue of miR-124 downregulation.

Cellular Senescence in Neurodegenerative Diseases

Cellular senescence is a homeostatic biological process characterized by a permanent state of cell cycle arrest that can contribute to the decline of the regenerative potential and function of tissues. The increased presence of senescent cells in different neurodegenerative diseases suggests the contribution of senescence in the pathophysiology of these disorders. Although several factors can induce senescence, DNA damage, oxidative stress, neuroinflammation, and altered proteostasis have been shown to play a role in its onset. Oxidative stress contributes to accelerated aging and cognitive dysfunction stages affecting neurogenesis, neuronal differentiation, connectivity, and survival. During later life stages, it is implicated in the progression of cognitive decline, synapse loss, and neuronal degeneration. Also, neuroinflammation exacerbates oxidative stress, synaptic dysfunction, and neuronal death through the harmful effects of pro-inflammatory cytokines on cell proliferation and maturation. Both oxidative stress and neuroinflammation can induce DNA damage and alterations in DNA repair that, in turn, can exacerbate them. Another important feature associated with senescence is altered proteostasis. Because of the disruption in the function and balance of the proteome, senescence can modify the proper synthesis, folding, quality control, and degradation rate of proteins producing, in some diseases, misfolded proteins or aggregation of abnormal proteins. There is an extensive body of literature that associates cellular senescence with several neurodegenerative disorders including Alzheimer’s disease (AD), Down syndrome (DS), and Parkinson’s disease (PD). This review summarizes the evidence of the shared neuropathological events in these neurodegenerative diseases and the implication of cellular senescence in their onset or aggravation. Understanding the role that cellular senescence plays in them could help to develop new therapeutic strategies.

Calcitriol Inhibits the Proliferation of Triple-Negative Breast Cancer Cells through a Mechanism Involving the Proinflammatory Cytokines IL-1β and TNF-α

Triple-negative breast cancer (TNBC) is one of the most aggressive tumors, with poor prognosis and high metastatic capacity. The aggressive behavior may involve inflammatory processes characterized by deregulation of molecules related to the immunological responses in which interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) are involved. It is known that calcitriol, the active vitamin D metabolite, modulates the synthesis of immunological mediators; however, its role in the regulation of IL-1β and TNF-α in TNBC has been scarcely studied. In the present study, we showed that TNBC cell lines SUM-229PE and HCC1806 expressed vitamin D, IL-1β, and TNF-α receptors. Moreover, calcitriol, its analogue EB1089, IL-1β, and TNF-α inhibited cell proliferation. In addition, we showed that synthesis of both IL-1β and TNF-α was stimulated by calcitriol and its analogue. Interestingly, the antiproliferative activity of calcitriol was significantly abrogated when the cells were treated with anti-IL-1β receptor 1 (IL-1R1) and anti-TNF-α receptor type 1 (TNFR1) antibodies. Furthermore, the combination of calcitriol with TNF-α resulted in a greater antiproliferative effect than either agent alone, in the two TNBC cell lines and an estrogen receptor-positive cell line. In summary, this study demonstrated that calcitriol exerted its antiproliferative effects in part by inducing the synthesis of IL-1β and TNF-α through IL-1R1 and TNFR1, respectively, in TNBC cells, highlighting immunomodulatory and antiproliferative functions of calcitriol in TNBC tumors.

Anti-IL17 treatment ameliorates Down syndrome phenotypes in mice

Down syndrome (DS) is characterized by structural and functional anomalies that are present prenatally and that lead to intellectual disabilities. Later in life, the cognitive abilities of DS individuals progressively deteriorate due to the development of Alzheimer's disease (AD)-associated neuropathology (i.e., β-amyloid (Aβ) plaques, neurofibrillary tangles (NFTs), neurodegeneration, synaptic pathology, neuroinflammation and increased oxidative stress). Increasing evidence has shown that among these pathological processes, neuroinflammation plays a predominant role in AD etiopathology. In AD mouse models, increased neuroinflammation appears earlier than Aβ plaques and NFTs, and in DS and AD models, neuroinflammation exacerbates the levels of soluble and insoluble Aβ species, favoring neurodegeneration. The Ts65Dn (TS) mouse, the most commonly used murine model of DS, recapitulates many alterations present in both DS and AD individuals, including enhanced neuroinflammation. In this study, we observed an altered neuroinflammatory milieu in the hippocampus of the TS mouse model. Pro-inflammatory mediators that were elevated in the hippocampus of this model included pro-inflammatory cytokine IL17A, which has a fundamental role in mediating brain damage in neuroinflammatory processes. Here, we analyzed the ability of an anti-IL17A antibody to reduce the neuropathological alterations that are present in TS mice during early neurodevelopmental stages (i.e., hippocampal neurogenesis and hypocellularity) or that are aggravated in later-life stages (i.e., cognitive abilities, cholinergic neuronal loss and increased cellular senescence, APP expression, Aβ peptide expression and neuroinflammation). Administration of anti-IL17 for 5 months, starting at the age of 7 months, partially improved the cognitive abilities of the TS mice, reduced the expression of several pro-inflammatory cytokines and the density of activated microglia and normalized the APP and Aβ_1-42 levels in the hippocampi of the TS mice. These results suggest that IL17-mediated neuroinflammation is involved in several AD phenotypes in TS mice and provide a new therapeutic target to reduce these pathological characteristics.

Vandetanib and cabozantinib potentiate mitochondria-targeted agents to suppress medullary thyroid carcinoma cells

Although the FDA-approved receptor tyrosine kinases inhibitors, vandetanib and cabozantinib, are used to treat surgically inoperable progressive medullary thyroid carcinoma (MTC), not all patients are responsive while the disease sometimes progresses after an initial response. To better understand MTC drug resistance at molecular and biochemical levels, we have generated drug-resistant subpopulations of the human MTC cell lines, TT and MZ-CRC-1, via prolonged exposure to vandetanib and cabozantinib. These drug-resistant progenies exhibited substantial cross-resistance to vandetanib and cabozantinib, suggesting that these inhibitors may invoke an overlapping resistance mechanism(s) in MTC cells. Of note, vandetanib and cabozantinib increased mitochondrial membrane potential (Δψ_m) in drug-naïve as well as drug-resistant cells but only drug-naïve cells exhibited substantially altered oxygen consumption and extracellular acidification rates. Therefore, these inhibitors appear to cause a bioenergetics stress to which drug-resistant MTC cells are more tolerant. Given the ability of vandetanib and cabozantinib to increase Δψ_m, we hypothesized that these inhibitors can augment growth inhibitory effects of mitochondria-targeted carboxy-proxyl and ubiquinone by increasing their Δψ_m-dependent uptake/retention in MTC cells. Indeed, our in vitro and mouse xenograft data strongly support this possibility.

Selective Mitochondrial Uptake of MKT-077 Can Suppress Medullary Thyroid Carcinoma Cell Survival In Vitro and In Vivo

BACKGROUND

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor mainly caused by mutations in the rearranged during transfection (RET) proto-oncogene. Not all patients with progressive MTC respond to current therapy inhibiting RET, demanding additional therapeutic strategies. We recently demonstrated that disrupting mitochondrial metabolism using a mitochondria-targeted agent or by depleting a mitochondrial chaperone effectively suppressed human MTC cells in culture and in mouse xenografts by inducing apoptosis and RET downregulation. These observations led us to hypothesize that mitochondria are potential therapeutic targets for MTC. This study further tests this hypothesis using1-ethyl-2-[[3-ethyl-5-(3-methylbenzothiazolin-2-yliden)]-4-oxothiazolidin-2-ylidenemethyl] pyridinium chloride (MKT-077), a water-soluble rhodocyanine dye analogue, which can selectively accumulate in mitochondria.

METHODS

The effects of MKT-077 on cell proliferation, survival, expression of RET and tumor protein 53 (TP53), and mitochondrial activity were determined in the human MTC lines in culture and in mouse xenografts.

RESULTS

MKT-077 induced cell cycle arrest in TT and MZ-CRC-1. Intriguingly, MKT-077 also induced RET downregulation and strong cell death responses in TT cells, but not in MZ-CRC-1 cells. This discrepancy was mainly due to the difference between the capacities of these cell lines to retain MKT-077 in mitochondria. The cytotoxicity of MKT-077 in TT cells was mainly attributed to oxidative stress while being independent of TP53. MKT-077 also effectively suppressed tumor growth of TT xenografts.

CONCLUSION

MKT-077 can suppress cell survival of certain MTC subtypes by accumulating in mitochondria and interfering with mitochondrial activity although it can also suppress cell proliferation via other mechanisms. These results consistently support the hypothesis that mitochondrial targeting has therapeutic potential for MTC.

Mortalin (GRP75/HSPA9) upregulation promotes survival and proliferation of medullary thyroid carcinoma cells

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor mainly caused by mutations in the rearranged during transfection (RET) proto-oncogene. For therapy of advanced MTC, the Food and Drug Administration recently approved vandetanib and cabozantinib, the tyrosine kinase inhibitors targeting RET, vascular endothelial growth factor receptor, epidermal growth factor receptor and/or c-MET. Nevertheless, not all patients respond to these drugs, demanding additional therapeutic strategies. We found that mortalin (HSPA9/GRP75), a member of HSP70 family, is upregulated in human MTC tissues and that its depletion robustly induces cell death and growth arrest in MTC cell lines in culture and in mouse xenografts. These effects were accompanied by substantial downregulation of RET, induction of the tumor-suppressor TP53 and altered expression of cell cycle regulatory machinery and apoptosis markers, including E2F-1, p21(CIP1), p27(KIP1) and Bcl-2 family proteins. Our investigation of the molecular mechanisms underlying these effects revealed that mortalin depletion induces transient MEK/ERK (extracellular signal-regulated kinase) activation and altered mitochondrial bioenergetics in MTC cells, as indicated by depolarized mitochondrial membrane, decreased oxygen consumption and extracellular acidification and increased oxidative stress. Intriguingly, mortalin depletion induced growth arrest partly via the MEK/ERK pathway, whereas it induced cell death by causing mitochondrial dysfunction in a Bcl-2-dependent manner. However, TP53 was not necessary for these effects except for p21(CIP1) induction. Moreover, mortalin depletion downregulated RET expression independently of MEK/ERK and TP53. These data demonstrate that mortalin is a key regulator of multiple signaling and metabolic pathways pivotal to MTC cell survival and proliferation, proposing mortalin as a novel therapeutic target for MTC.

Could signal transducer and activator of transcription 3 be a therapeutic target in obesity-related gastrointestinal malignancy?

INTRODUCTION

A large body of evidence has implicated the signal transducer and activator of transcription (STAT) family and particularly the ubiquitously expressed STAT3 protein in the pathogenesis of colorectal, hepatocellular, gastric and pancreatic carcinoma.

DISCUSSION

Concomitantly, an increasing body of epidemiological evidence has linked obesity and its associated pro-inflammatory state with the development of gastrointestinal cancers. Visceral adipose tissue is no longer considered inert and is known to secrete a number of adipocytokines such as leptin, interleukin (IL)-6, IL-8, IL-1β and tumour necrosis factor-alpha (TNF-α) into the surrounding environment. Interestingly, these adipocytokines are strongly linked with the Janus kinase (JAK)/STAT pathway of signal transduction and there is experimental evidence linking IL-1β, IL-8 and TNF-α to JAK/STAT signaling in other tissues. The result is an up-regulation of a wide range of anti-apoptotic, pro-metastatic and pro-angiogenic genes and processes. This is particularly relevant for gastrointestinal malignancy as these factors have the potential to signal adjacent endothelial cells in a paracrine manner.

CONCLUSION

This review examines the potential role of the STAT3 signaling pathway in the pathogenesis of obesity-related gastrointestinal malignancy and the potential therapeutic role of STAT3 blockade given its status as a signaling hub for a number of inflammatory adipocytokines.

Growth arrest signaling of the Raf/MEK/ERK pathway in cancer

The Raf/MEK/extracellular signal-regulated kinase (ERK) pathway has a pivotal role in facilitating cell proliferation, and its deregulated activation is a central signature of many epithelial cancers. However paradoxically, sustained activity of Raf/MEK/ERK can also result in growth arrest in many different cell types. This anti-proliferative Raf/MEK/ERK signaling also has physiological significance, as exemplified by its potential as a tumor suppressive mechanism. Therefore, significant questions include in which cell types and by what mechanisms this pathway can mediate such an opposing context of signaling. Particularly, our understating of the role of ERK1 and ERK2, the focal points of pathway signaling, in growth arrest signaling is still limited. This review discusses these aspects of Raf/MEK/ERK-mediated growth arrest signaling.

The Role of STAT3 in Thyroid Cancer

Thyroid cancer is the most common endocrine malignancy and its global incidence rates are rapidly increasing. Although the mortality of thyroid cancer is relatively low, its rate of recurrence or persistence is relatively high, contributing to incurability and morbidity of the disease. Thyroid cancer is mainly treated by surgery and radioiodine remnant ablation, which is effective only for non-metastasized primary tumors. Therefore, better understanding of the molecular targets available in this tumor is necessary. Similarly to many other tumor types, oncogenic molecular alterations in thyroid epithelium include aberrant signal transduction of the mitogen-activated protein kinase, phosphatidylinositol 3-kinase/AKT (also known as protein kinase B), NF-кB, and WNT/β-catenin pathways. However, the role of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT3) pathway, a well-known mediator of tumorigenesis in different tumor types, is relatively less understood in thyroid cancer. Intriguingly, recent studies have demonstrated that, in thyroid cancer, the JAK/STAT3 pathway may function in the context of tumor suppression rather than promoting tumorigenesis. In this review, we provide an update of STAT3 function in thyroid cancer and discuss some of the evidences that support this hypothesis.

Involvement of the NLRP3 inflammasome in the modulation of an LPS-induced inflammatory response during morphine tolerance

BACKGROUND

Morphine is widely used for its analgesic effects. In addition to its high potential for addiction and tolerance, morphine also induces immunosuppression. Inflammasomes, NLRP3 being the most characterized, is a platform for activation of pro-inflammatory cytokines, particularly IL-1β. We have explored the effects of lipopolysaccharide (LPS) during morphine tolerance on expression of the NLRP3 inflammasome and related inflammatory genes.

METHODS

Morphine-pellet administration was used to induce morphine tolerance in F344 rats. Control rats were given a placebo. On day 5, the animals received either saline or 250 μg/kg LPS. LPS-induced protein expression of TNF-α, IL-1β, and IL- 6 was examined in the spleen of rats with and without morphine tolerance. A PCR array was used to examine LPS-induced expression of 84 inflammasome-related genes with and without morphine tolerance.

RESULTS

LPS-induced IL-1β and TNF-α protein expression was significantly lower in the spleen of the morphine-tolerant animals than in the placebo-control animals. In response to LPS, expression of 27 genes, including NLRP3, TNF-α, IL-1β, and IL-6, was significantly increased, and expression of 3 genes was significantly decreased in both the morphine-tolerant and placebo-control groups compared to the saline-treated animals. However, there was only a 2.7-fold increase in NLRP3 expression in response to LPS in the morphine-tolerant rats compared to a 4.5-fold increase in the placebo-control animals.

CONCLUSION

Our data indicate that, in the morphine-tolerant state, LPS-induced expression of NLRP3 is suppressed and cytokine/chemokine expression is inhibited, which may be one of the mechanisms involved in morphine-induced immunosuppression.

Down's syndrome, neuroinflammation, and Alzheimer neuropathogenesis

Down syndrome (DS) is the result of triplication of chromosome 21 (trisomy 21) and is the prevailing cause of mental retardation. In addition to the mental deficiencies and physical anomalies noted at birth, triplication of chromosome 21 gene products results in the neuropathological and cognitive changes of Alzheimer's disease (AD). Mapping of the gene that encodes the precursor protein (APP) of the β-amyloid (Aβ) present in the Aβ plaques in both AD and DS to chromosome 21 was strong evidence that this chromosome 21 gene product was a principal neuropathogenic culprit in AD as well as DS. The discovery of neuroinflammatory changes, including dramatic proliferation of activated glia overexpressing a chromosome 2 gene product--the pluripotent immune cytokine interleukin-1 (IL-1)--and a chromosome 21 gene product--S100B--in the brains of fetuses, neonates, and children with DS opened the possibility that early events in Alzheimer pathogenesis were driven by cytokines. The specific chromosome 21 gene products and the complexity of the mechanisms they engender that give rise to the neuroinflammatory responses noted in fetal development of the DS brain and their potential as accelerators of Alzheimer neuropathogenesis in DS are topics of this review, particularly as they relate to development and propagation of neuroinflammation, the consequences of which are recognized clinically and neuropathologically as Alzheimer's disease.

Recombinant leukemia inhibitory factor suppresses human medullary thyroid carcinoma cell line xenografts in mice

Medullary thyroid carcinoma (MTC) is a neoplasm of the endocrine system, which originates from parafollicular C-cells of the thyroid gland. For MTC therapy, the Food and Drug Administration recently approved vandetanib and cabozantinib, multi-kinase inhibitors targeting RET and other tyrosine kinase receptors of vascular endothelial growth factor, epidermal growth factor, or hepatocyte growth factor. Nevertheless, not all patients with the progressive MTC respond to these drugs, requiring the development of additional therapeutic modalities that have distinct activity. Previously, we reported that expression of activated Ras or Raf in the human MTC cell lines, TT and MZ-CRC-1, can induce growth arrest and RET downregulation via a leukemia inhibitory factor (LIF)-mediated autocrine/paracrine loop. In this study, we aimed to evaluate bacterially-produced recombinant human LIF for its efficacy to suppress human MTC xenografts in mice. Here, we report that, consistent with its effects in vitro, locally or systemically administered recombinant LIF effectively suppressed growth of TT and MZ-CRC-1 xenografts in mice. Further, as predicted from its effects in TT and MZ-CRC-1 cell cultures in vitro, recombinant LIF activated the JAK/STAT pathway and downregulated RET and E2F1 expression in tumors in mice. These results suggest that LIF is a potent cytostatic agent for MTC cells, which regulates unique mechanisms that are not targeted by currently available therapeutic agents.

Mitochondria-targeted nitroxide, Mito-CP, suppresses medullary thyroid carcinoma cell survival in vitro and in vivo

CONTEXT

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor mainly caused by mutations in the RET proto-oncogene. For MTC therapy, the U.S. Food and Drug Administration recently approved vandetanib and cabozantinib, multikinase inhibitors targeting RET and other tyrosine kinase receptors of vascular endothelial growth factor, epidermal growth factor, or hepatocyte growth factor. Nevertheless, not all patients with the progressive MTC respond to these drugs, requiring the development of additional therapeutic modalities that have distinct activity.

OBJECTIVE

We aimed to evaluate mitochondria-targeted carboxy-proxyl (Mito-CP), a mitochondria-targeted redox-sensitive agent, for its tumor-suppressive efficacy against MTC.

DESIGN

In vitro cultures of 2 human MTC cell lines, TT and MZ-CRC-1, and TT xenografts in mice were treated with Mito-CP in comparison with vandetanib. The effects on cell survival/death, RET expression, mitochondrial integrity, and oxidative stress were determined.

RESULTS

Contrary to vandetanib, Mito-CP induced RET downregulation and strong cytotoxic effects in both cell lines in vitro, including caspase-dependent apoptosis. These effects were accompanied by mitochondrial membrane depolarization, decreased oxygen consumption, and increased oxidative stress in cells. Intriguingly, Mito-CP-induced cell death, but not RET downregulation, was partially inhibited by the reactive oxygen species scavenger, N-acetyl-cysteine, indicating that Mito-CP mediates tumor-suppressive effects via redox-dependent as well as redox-independent mechanisms. Orally administered Mito-CP effectively suppressed TT xenografts in mice, with an efficacy comparable to vandetanib and relatively low toxicity to animals.

CONCLUSION

Our results suggest that Mito-CP can effectively suppress MTC cell growth/survival via a mechanism distinct from vandetanib effects. Mitochondrial targeting may be a potential strategy for MTC therapy.

Leukemia inhibitory factor in rat fetal lung development: expression and functional studies

Background

Leukemia inhibitory factor (LIF) and interleukin-6 (IL-6) are members of the family of the glycoprotein 130 (gp130)-type cytokines. These cytokines share gp130 as a common signal transducer, which explains why they show some functional redundancy. Recently, it was demonstrated that IL-6 promotes fetal lung branching. Additionally, LIF has been implicated in developmental processes of some branching organs. Thus, in this study LIF expression pattern and its effects on fetal rat lung morphogenesis were assessed.

Methodology/Principal Findings

LIF and its subunit receptor LIFRα expression levels were evaluated by immunohistochemistry and western blot in fetal rat lungs of different gestational ages, ranging from 13.5 to 21.5 days post-conception. Throughout all gestational ages studied, LIF was constitutively expressed in pulmonary epithelium, whereas LIFRα was first mainly expressed in the mesenchyme, but after pseudoglandular stage it was also observed in epithelial cells. These results point to a LIF epithelium-mesenchyme cross-talk, which is known to be important for lung branching process. Regarding functional studies, fetal lung explants were cultured with increasing doses of LIF or LIF neutralizing antibodies during 4 days. MAPK, AKT, and STAT3 phosphorylation in the treated lung explants was analyzed. LIF supplementation significantly inhibited lung growth in spite of an increase in p44/42 phosphorylation. On the other hand, LIF inhibition significantly stimulated lung growth via p38 and Akt pathways.

Conclusions/Significance

The present study describes that LIF and its subunit receptor LIFRα are constitutively expressed during fetal lung development and that they have an inhibitory physiological role on fetal lung branching.

Suppressors of cytokine signaling inhibit tubular epithelial cell-myofibroblast transdifferentiation

BACKGROUND/AIMS

Tubular epithelial cell-myofibroblast transdifferentiation (TEMT) can be induced by diverse cytokines. The suppressors of cytokine signaling (SOCS) proteins negatively regulate cytokine signaling. This study is aimed at examining the role of SOCS-1 and SOCS-3 in TEMT induced by cytokines.

METHODS

The cell ultrastructure was observed using transmission electron microscopy. The protein and mRNA levels of cytokeratin 18 (CK18) and α-smooth muscle actin (α-SMA) were detected by immunocytochemistry, Western blot and real-time PCR. The levels of phosphorylated-signal transducer and activator of transcription (p-STAT) 1 and 3 were detected by Western blot. The protein and mRNA levels of SOCS-1 and SOCS-3 were detected by Western blot and real-time PCR. The levels of collagen type I and fibronectin (FN) were determined by ELISA.

RESULTS

Interleukin-1β (IL-1β) and oncostatin M (OSM) were able to downregulate CK18 expression and upregulate α-SMA, p-STAT1, p-STAT3, collagen type I and FN expression in cultured human renal proximal tubular epithelial cells (HKCs), whereas pretreatment with AG490 prevented these expression changes from occurring. All of the changes induced by IL-1β or OSM could be decreased by SOCS-1 and SOCS-3 overexpression, and were increased by SOCS-1 and SOCS-3 knockdown.

CONCLUSIONS

SOCS-1 and SOCS-3 can prevent tubulointerstitial fibrosis by inhibiting TEMT, which may be connected with the activation of STAT1 and STAT3.

Dual regulation of mu opioid receptors in SK-N-SH neuroblastoma cells by morphine and interleukin-1β: evidence for opioid-immune crosstalk

Treatment of SK-N-SH cells with morphine and interleukin-1beta (IL-1β) produced dual regulation of the mRNA for the human mu opioid receptor (MOR) protein. Morphine produced a decrease in the MOR mRNA while IL-1β increased it, as assessed by real-time quantitative PCR. These data were consistent with immunocytochemical studies of treated and untreated cells. Morphine-mediated down-regulation of MOR was blocked by naltrexone and IL-1β-induced up-regulation of MOR was blocked by interleukin-1 receptor type 1 antagonist. Immune-opioid crosstalk was examined by IL-1β and morphine co-treatment. These data are the first to show dual regulation of MOR in neuroblastoma cells.

Leukemia inhibitory factor can mediate Ras/Raf/MEK/ERK-induced growth inhibitory signaling in medullary thyroid cancer cells

Medullary thyroid carcinoma (MTC) is a multiple endocrine neoplasia type 2 syndrome caused by mutations in extracellular receptor or intracellular kinase domains of the RET proto-oncogene. Activation of the Ras/Raf/MEK/ERK pathway can lead to growth arrest by secreting leukemia inhibitory factor (LIF) in MTC cells harboring a RET receptor domain mutation. Here, we report that Ras/Raf/MEK/ERK can also mediate, via LIF, growth inhibition in MTC cells harboring a RET kinase domain mutation. Ras/Raf/MEK/ERK activation was sufficient to induce growth inhibition and LIF expression in the human MTC line MZ-CRC-1. Presence of LIF-mediated signaling was determined by blocking the activity of culture medium conditioned by Raf-activated cells using anti-LIF neutralizing antibody. In addition, recombinant LIF effectively suppressed cell proliferation via cell cycle arrest in G0/G1 phase. Expression of dominant negative STAT3 abrogated LIF effects, indicating that LIF mediates its signaling through the JAK/STAT3 pathway. These results suggest that growth inhibition and activation of the autocrine/paracrine signaling through LIF/JAK/STAT may be a common response to Ras/Raf activation in different MTC types, and justify further evaluation of LIF as a potential anticancer agent for MTC.

A rapid bioassay for recombinant interleukin-22

Interleukin-22 is a novel cytokine produced mainly in activated T cells. The elaborate biological functions of IL-22 in vivo are still widely unknown. In this report, we describe a rapid, simple, and reproducible in vitro cell-based bioassay for measuring the bioactivity of recombinant interleukin-22 (IL-22) to study the primary function of IL-22 in vivo. Human hepatocyte cell line (HepG2) was transfected with pSTAT3-Luc, a plasmid carrying the luciferase gene under the control of STAT3. After screening and selection, one stable clone was established which generates a strong response to recombinant human IL-22 (rhIL-22) stimulation in a dose-dependent manner. The cell showed ED50 of 17.0 +/- 1.4 ng/mL (n = 15) to recombinant human IL-22. Pre-incubation of anti-IL-22 mAb with IL-22 recombinant proteins completely blocked the bioactivities. The assay can be completed within one day. The current assay provides a rapid analytical method to measure the biological activity of IL-22 in vitro.

Noncatalytic function of ERK1/2 can promote Raf/MEK/ERK-mediated growth arrest signaling

Kinase activity is known as the key biochemical property of MAPKs. Here, we report that ERK1/2 also utilizes its noncatalytic function to mediate certain signal transductions. Sustained activation of the Raf/MEK/ERK pathway induces growth arrest, accompanied by changes in cell cycle regulators (decreased retinoblastoma phosphorylation, E2F1 down-regulation, and/or p21(CIP1) up-regulation) and cell type-specific changes in morphology and expression of c-Myc or RET in the human tumor lines LNCaP, U251, and TT. Ablation of ERK1/2 by RNA interference abrogated all these effects. However, active site-disabled ERK mutants (ERK1-K71R, ERK2-K52R, and ERK2-D147A), which competitively inhibit activation of endogenous ERK1/2, could not block Raf/MEK-induced growth arrest as well as changes in the cell cycle regulators, although they effectively blocked phosphorylation of the ERK1/2 catalytic activity readouts, p90(RSK) and ELK1, as well as the cell type-specific changes. Because this indicated a potential noncatalytic ERK1/2 function, we generated stable lines of the tumor cells in which both ERK1 and ERK2 were significantly knocked down, and we further investigated the possibility using rat-derived kinase-deficient ERK mutants (ERK2-K52R and ERK2-T183A/Y185F) that were not targeted by human small hairpin RNA. Indeed, ERK2-K52R selectively restored Raf-induced growth inhibitory signaling in ERK1/2-depleted cells, as manifested by regained cellular ability to undergo growth arrest and to control the cell cycle regulators without affecting c-Myc and morphology. However, ERK2-T183A/Y185F was less effective, indicating the requirement of TEY site phosphorylation. Our study suggests that functions of ERK1/2 other than its "canonical" kinase activity are also involved in the pathway-mediated growth arrest signaling.

Hepatocyte growth factor induces delayed STAT3 phosphorylation through interleukin-6 expression

Met receptor tyrosine kinase mediates pleiotropic cellular responses following its activation by hepatocyte growth factor or scatter factor (HGF/SF). STAT3 was reported to be one of direct downstream molecules in HGF/SF-Met signaling. In the present study, however, we observed that Tyr705 of STAT3 was phosphorylated from 2 h or 6 h in NIH3T3 and Chang liver cells, respectively, after HGF/SF treatment. Blocking of the phosphorylation by cycloheximide or actinomycin D and the rapid STAT3 phosphorylation with the conditioned medium from HGF/SF-treated NIH3T3 cells suggested that a newly synthesized secretory protein was responsible for the delayed STAT3 phosphorylation. Among the known mediators to induce STAT3 phosphorylation, interleukin-6 (IL-6) mRNA and protein were induced by HGF/SF, and the released IL-6 was accumulated in the conditioned medium after HGF/SF treatment. Furthermore, the neutralizing IL-6 antibody abolished the STAT3 phosphorylation. Treatment with LY294002, a PI3 kinase inhibitor, but not with other signal inhibitors, resulted in the loss of delayed STAT3 phosphorylation by HGF/SF, showing the involvement of PI3 kinase pathway. Collectively, these results demonstrate that HGF/SF-Met signal cascade stimulates IL-6 production via PI3 kinase pathway, leading to STAT3 phosphorylation as a secondary effect.

Persistent fetal infection with bovine viral diarrhea virus differentially affects maternal blood cell signal transduction pathways

The consequences of viral infection during pregnancy include impact on fetal and maternal immune responses and on fetal development. Transplacental infection in cattle with noncytopathic bovine viral diarrhea virus (ncpBVDV) during early gestation results in persistently infected (PI) fetuses with life-long viremia and susceptibility to infections. Infection of the fetus during the third trimester or after birth leads to a transient infection cleared by a competent immune system. We hypothesized that ncpBVDV infection and presence of an infected fetus would alter immune response and lead to downregulation of proinflammatory processes in pregnant dams. Naïve pregnant heifers were challenged with ncpBVDV2 on day 75 (PI fetus) and day 175 [transiently infected (TI) fetus] or kept uninfected (healthy control fetus). Maternal blood samples were collected up to day 190 of gestation. Genome-wide microarray analysis of gene expression in maternal peripheral white blood cells, performed on days 160 and 190 of gestation, revealed multiple signal transduction pathways affected by ncpBVDV infection. Acute infection and presence of a TI fetus caused upregulation of the type I interferon (IFN) pathway genes, including dsRNA sensors and IFN-stimulated genes. The presence of a PI fetus caused prolonged downregulation of chemokine receptor 4 (CXCR4) and T cell receptor (TCR) signaling in maternal blood cells. We conclude that: 1) infection with ncpBVDV induces a vigorous type I IFN response, and 2) presence of a PI fetus causes downregulation of important signaling pathways in the blood of the dam, which could have deleterious consequences on fetal development and the immune response.

LIF upregulates expression of NK-1R in NHBE cells

Leukemia inhibitory factor (LIF), a cytokine at the interface between neurobiology and immunology, is mainly mediated through JAK/STAT pathway and MAPK/ERK pathway. Evidence suggested LIF is related to the higher expression of neurokinin-1 receptor (NK-1R) in asthma. In this study, the immunohistochemistry stain showed the expressions of NK-1R, LIF, p-STAT3, and p-ERK1/2 in the lung tissues of allergic rats were increased compared with the controls, and the main positive cell type was airway epithelial cell. Normal human bronchial epithelial cells were treated with LIF in the presence or absence of AG490 (JAK2 inhibitor), PD98059 (MEK inhibitor), and the siRNA against STAT3. Western blot and RT-PCR indicated that LIF induced the expression of NK-1R, which was inhibited by the inhibitors mentioned above. No significant interaction was found between JAK/STAT pathway and MAPK/ERK pathway. In summary, bronchial epithelial cell changes in asthma are induced by LIF which promotes the expression of NK-1R, and JAK/STAT pathway and MAPK/ERK pathway may participate in this process.