Antiapoptotic signalling by the insulin-like growth factor I receptor, phosphatidylinositol 3-kinase, and Akt

Cancer Resistance Is Mediated by the Upregulation of Several Anti-Apoptotic Gene Products via the Inducible Nitric Oxide Synthase/Nitric Oxide Pathway: Therapeutic Implications

Significance: Several therapeutic strategies for cancer treatments have been developed with time, and significant milestones have been achieved recently. However, with these novel therapies, not all cancer types respond and in the responding cancer types only a subset is affected. The failure to respond is principally the result that these cancers develop several mechanisms of resistance. Thus, a focus of current research investigations is to unravel the various mechanisms that regulate resistance and identify suitable targets for new therapeutics. Recent Advances: Hence, many human cancer types have been reported to overexpress the inducible nitric oxide synthase (iNOS) and it has been suggested that iNOS/nitric oxide (NO) plays a pivotal role in the regulation of resistance. We have postulated that iNOS overexpression or NO regulates the overexpression of pivotal anti-apoptotic gene products such as B-cell lymphoma 2 (Bcl-2), B-cell lymphoma extra large (Bcl-xL), myeloid cell leukemia-1 (Mcl-1), and survivin. In this report, we describe the various mechanisms, transcriptional, post-transcriptional, and post-translational, by which iNOS/NO regulates the expression of the above anti-apoptotic gene products. Critical Issues: The iNOS/NO-mediated regulation of the four gene products is not the same with both specific and overlapping pathways. Our findings are, in large part, validated by bioinformatic analyses demonstrating, in several cancers, several direct correlations between the expression of iNOS and each of the four examined anti-apoptotic gene products. Future Directions: We have proposed that targeting iNOS may be highly efficient since it will result in the underexpression of multiple anti-apoptotic proteins and shifting the balance toward the proapoptotic gene products and reversal of resistance. Antioxid. Redox Signal. 39, 853-889.

Changes in the Acetylcholinesterase Enzymatic Activity in Tumor Development and Progression

Acetylcholinesterase is a well-known protein because of the relevance of its enzymatic activity in the hydrolysis of acetylcholine in nerve transmission. In addition to the catalytic action, it exerts non-catalytic functions; one is associated with apoptosis, in which acetylcholinesterase could significantly impact the survival and aggressiveness observed in cancer. The participation of AChE as part of the apoptosome could explain the role in tumors, since a lower AChE content would increase cell survival due to poor apoptosome assembly. Likewise, the high Ach content caused by the reduction in enzymatic activity could induce cell survival mediated by the overactivation of acetylcholine receptors (AChR) that activate anti-apoptotic pathways. On the other hand, in tumors in which high enzymatic activity has been observed, AChE could be playing a different role in the aggressiveness of cancer; in this review, we propose that AChE could have a pro-inflammatory role, since the high enzyme content would cause a decrease in ACh, which has also been shown to have anti-inflammatory properties, as discussed in this review. In this review, we analyze the changes that the enzyme could display in different tumors and consider the different levels of regulation that the acetylcholinesterase undergoes in the control of epigenetic changes in the mRNA expression and changes in the enzymatic activity and its molecular forms. We focused on explaining the relationship between acetylcholinesterase expression and its activity in the biology of various tumors. We present up-to-date knowledge regarding this fascinating enzyme that is positioned as a remarkable target for cancer treatment.

GH and Childhood-onset Craniopharyngioma: When to Initiate GH Replacement Therapy?

CONTEXT

Craniopharyngioma is a benign brain tumor with frequent local recurrence or progression after treatment. GH replacement therapy (GHRT) is prescribed in children with GH deficiency resulting from childhood-onset craniopharyngioma.

OBJECTIVE

To evaluate whether a shorter delay of GHRT initiation after childhood-onset craniopharyngioma completion therapy increased the risk of a new event (progression or recurrence).

METHODS

Retrospective, observational, monocenter study. We compared a cohort of 71 childhood-onset patients with craniopharyngiomas treated with recombinant human GH (rhGH). Twenty-seven patients were treated with rhGH at least 12 months after craniopharyngioma treatment (>12-month group) and 44 patients before 12 months (<12-month group), among which 29 patients were treated between 6 and 12 months (6-12 month group). The main outcome was the risk of tumor new event (progression of residual tumor or tumor recurrence after complete resection) after primary treatment in the >12-month group and in the <12 month or in the 6- to 12-month group patients.

RESULTS

In the >12-month group, the 2- and 5-year event-free survivals were respectively 81.5% (95% CI, 61.1-91.9) and 69.4% (95% CI, 47.9-83.4) compared with 72.2% (95% CI, 56.3-83.1) and 69.8% (95% CI, 53.8-81.2) in the <12-month group. The 2- and 5-year event-free survivals were the same in the 6- to 12-month group (72.4%; 95% CI, 52.4-85.1). By log-rank test, the event-free survival was not different between groups (P = .98 and P = .91).The median time for event was not statistically different.In univariate and multivariate analysis, the risk of craniopharyngioma new event was not associated with the GHRT time delay after craniopharyngioma treatment.

CONCLUSIONS

No association was found between GHRT time delay after childhood-onset craniopharyngioma treatment and an increased risk of recurrence or tumor progression, suggesting GH replacement therapy can be initiated 6 months after last treatment for craniopharyngiomas.

A critical review on anti-fibrotic phytochemicals targeting activated hepatic stellate cells

Liver fibrosis is a major health concern occurring worldwide. It arises due to prolonged wound healing response of various insults like viral, autoimmune, cholestatic, drug-induced, and metabolic diseases. Currently, there is no clinically approved drug for liver fibrosis treatment. Hepatic stellate cells are the principal liver cells that are activated during liver fibrosis, and targeting these activated cells is an ideal therapeutic strategy. Numerous phytochemicals have been demonstrated in vitro and in vivo treating experimental liver fibrosis; however, none of them have been clinically approved for therapeutic use. This review mainly focuses on such hepatoprotective phytochemicals reported inhibiting major signaling pathways that are dysregulated in activated hepatic stellate cells. PRACTICAL APPLICATIONS: Liver fibrosis is a global health concern and there is no FDA approved drug to treat liver fibrosis. Although notable pharmacological agents like pentoxifylline, gliotoxin, imatinibmesylate, Gleevec, and so on are reported to exhibit anti-fibrotic effect, the major concern is their side effect. Hence, phytochemicals are promising candidates that could be employed against liver fibrosis. In this review, the anti-fibrotic potential of phytochemicals targeting activated HSCs are summarized. Understanding these phytochemicals will further help in the development of agents that are more effective against liver fibrosis.

The CX3CL1 intracellular domain exhibits neuroprotection via insulin receptor/ insulin like growth factor receptor signaling

CX3CL1, also known as fractalkine, is best known for its signaling activity through interactions with its cognate receptor CX3CR1. However, its intrinsic function that is independent of interaction with CX3CR1 remains to be fully understood. We demonstrate that the intracellular domain of CX3CL1 (CX3CL1-ICD), generated upon sequential cleavages by α-/β-secretase and γ-secretase, initiates a back signaling activity, which mediates direct signal transmission to gene expression in the nucleus. To study this, we fused a synthetic peptide derived from CX3CL1-ICD, named Tet34, with a 13-amino acid tetanus sequence at the N-terminus to facilitate translocation into neuronal cells. We show that treatment of mouse neuroblastoma Neuro-2A cells with Tet34, but not its scrambled control (Tet34s), induced cell proliferation, as manifested by changes in protein levels of transcription factors and pro-growth molecules Foxo-1, -3, cyclin D1, PCNA, Sox5, and cdk2. Further biochemical assays reveal elevation of phosphorylated insulin receptor β subunit, insulin-like growth factor-1 (IGF-1) receptor β subunit and insulin receptor substrates as well as activation of proliferation-linked kinase AKT. In addition, transgenic mice overexpressing membrane-anchored C-terminal CX3CL1 (CX3CL1- ct) also exhibited activation of insulin/IGF-1 receptor signaling. Remarkably, we found this Tet34 peptide, but not Tet34s, protected against endoplasmic reticulum stress and cellular apoptosis when Neuro-2A cells were challenged with toxic oligomers of β-amyloid peptide or hydrogen peroxide. Taken together, our results suggest CX3CL1-ICD may have translational potential for neuroprotection in Alzheimer's disease and for disorders resulting from insulin resistance.

Fluconazole Is Neuroprotective via Interactions with the IGF-1 Receptor

There is a continuing unmet medical need to develop neuroprotective strategies to treat neurodegenerative disorders. To address this need, we screened over 2000 compounds for potential neuroprotective activity in a model of oxidative stress and found that numerous antifungal agents were neuroprotective. Of the identified compounds, fluconazole was further characterized. Fluconazole was able to prevent neurite retraction and cell death in in vitro and in vivo models of toxicity. Fluconazole protected neurons in a concentration-dependent manner and exhibited efficacy against several toxic agents, including 3-nitropropionic acid, N-methyl D-aspartate, 6-hydroxydopamine, and the HIV proteins Tat and gp120. In vivo studies indicated that systemically administered fluconazole was neuroprotective in animals treated with 3-nitropropionic acid and prevented gp120-mediated neuronal loss. In addition to neuroprotection, fluconazole also induced proliferation of neural progenitor cells in vitro and in vivo. Fluconazole mediates these effects through upregulation and signaling via the insulin growth factor-1 receptor which results in decreased cAMP production and increased phosphorylation of Akt. Blockade of the insulin growth factor-1 receptor signaling with the selective inhibitor AG1024 abrogated the effects of fluconazole. Our studies suggest that fluconazole may be an attractive candidate for treatment of neurodegenerative diseases due to its protective properties against several categories of neuronal insults and its ability to spur neural progenitor cell proliferation.

Shared Molecular Mechanisms among Alzheimer’s Disease, Neurovascular Unit Dysfunction and Vascular Risk Factors: A Narrative Review

Alzheimer’s disease (AD) is the most common type of dementia, affecting 24 million individuals. Clinical and epidemiological studies have found several links between vascular risk factors (VRF), neurovascular unit dysfunction (NVUd), blood-brain barrier breakdown (BBBb) and AD onset and progression in adulthood, suggesting a pathogenetic continuum between AD and vascular dementia. Shared pathways between AD, VRF, and NVUd/BBB have also been found at the molecular level, underlining the strength of this association. The present paper reviewed the literature describing commonly shared molecular pathways between adult-onset AD, VRF, and NVUd/BBBb. Current evidence suggests that VRF and NVUd/BBBb are involved in AD neurovascular and neurodegenerative pathology and share several molecular pathways. This is strongly supportive of the hypothesis that the presence of VRF can at least facilitate AD onset and progression through several mechanisms, including NVUd/BBBb. Moreover, vascular disease and several comorbidities may have a cumulative effect on VRF and worsen the clinical manifestations of AD. Early detection and correction of VRF and vascular disease by improving NVUd/BBBd could be a potential target to reduce the overall incidence and delay cognitive impairment in AD.

BCR-ABL1 Tyrosine Kinase Complex Signaling Transduction: Challenges to Overcome Resistance in Chronic Myeloid Leukemia

The constitutively active BCR-ABL1 tyrosine kinase, found in t(9;22)(q34;q11) chromosomal translocation-derived leukemia, initiates an extremely complex signaling transduction cascade that induces a strong state of resistance to chemotherapy. Targeted therapies based on tyrosine kinase inhibitors (TKIs), such as imatinib, dasatinib, nilotinib, bosutinib, and ponatinib, have revolutionized the treatment of BCR-ABL1-driven leukemia, particularly chronic myeloid leukemia (CML). However, TKIs do not cure CML patients, as some develop TKI resistance and the majority relapse upon withdrawal from treatment. Importantly, although BCR-ABL1 tyrosine kinase is necessary to initiate and establish the malignant phenotype of Ph-related leukemia, in the later advanced phase of the disease, BCR-ABL1-independent mechanisms are also in place. Here, we present an overview of the signaling pathways initiated by BCR-ABL1 and discuss the major challenges regarding immunologic/pharmacologic combined therapies.

Tenofovir disoproxil fumarate directly ameliorates liver fibrosis by inducing hepatic stellate cell apoptosis via downregulation of PI3K/Akt/mTOR signaling pathway

Background

Antifibrotic agent for the treatment of liver fibrosis has not been developed so far. Long term treatment of chronic hepatitis B patients with antiviral drugs tenofovir disoproxil fumarate (TDF) and entecavir (ETV) results in the regression of liver fibrosis, but the underlying mechanism has not been clarified. Therefore, we aimed to investigate the direct impact of TDF and ETV on liver fibrosis.

Methods

Activated hepatic stellate cell (HSC) cell lines were used to evaluate the effects of TDF and ETV. After treatment with each antiviral agent, cell viability, morphology, apoptotic features, autophagy and antifibrosis signalling pathways were examined. Then, collagen deposition, fibrosis markers and activated HSCs were measured in liver tissues of the liver fibrosis model mice.

Results

After TDF treatment, the viabilities of LX2 and HSC-T6 cells were decreased, and the cells exhibited apoptotic features, but ETV did not induce these effects. Cleavage of PARP and Caspase-3 and the inhibition of the antiapoptotic gene Bcl-xl indicated activated HSC apoptosis following TDF treatment. TDF simultaneously increased autophagy, which also regulated apoptosis through crosstalk. TDF inactivated the PI3K/Akt/mTOR signalling pathway, which was associated with the activation of both apoptosis and autophagy. In the liver fibrosis mouse model, the fibrotic area and activated HSC markers were decreased by TDF but not ETV treatment. Additionally, apoptotic cells were concentrated in the periportal fibrotic area after TDF treatment, which indicated the specific antifibrotic effect of TDF.

Conclusions

TDF directly ameliorates liver fibrosis by downregulating the PI3K/Akt/mTOR signalling pathway, which results in the apoptosis of activated HSCs. The antifibrotic effects of TDF indicate that it may be a therapeutic agent for the treatment of liver fibrosis.

Molecular Studies on the Nephroprotective Potential of Celastrus paniculatus against Lead-Acetate-Induced Nephrotoxicity in Experimental Rats: Role of the PI3K/AKT Signaling Pathway

Chemicals can induce nephrotoxicity, with damage to different segments of the nephron and deterioration of renal function. Nephrotoxicity due to exposure to a toxin such as carbon tetrachloride, sodium oxalate, or heavy metals is the most common cause of kidney injury. The current study aimed to evaluate the protective effects of Celastrus paniculatus seed extract against lead-acetate-induced nephrotoxicity by evaluating the histopathology, immunohistochemistry, ultrastructure, and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway. Twenty-four rats were divided into four groups (n = 6 per group): group 1 contained normal animals and served as the control; group 2 received lead acetate (30 mg/kg body weight (b.w.)/day, oral); group 3 received lead acetate and the standard drug N-acetylcysteine (NAC, 200 mg/kg b.w./day, oral); and group 4 received lead acetate and the ethanolic extract of C. paniculatus seed (EECP; 800 mg/kg b.w./day, oral). Treatment was given for 28 consecutive days. The data were analyzed using one-way analysis of variance with SIGMA PLOT 13 using SYSTAT software followed by Newman–Keul’s test for comparison between the groups. EECP ameliorated the adverse changes caused by lead acetate. PI3K and AKT messenger RNA (mRNA) levels were diminished in lead-acetate-treated rats. Treatment with EECP inhibited the occurrence of shrunken cells, the atrophy of glomeruli, and degenerative changes in renal tubules caused by lead acetate. Interestingly, the PI3K and AKT mRNA levels were significantly increased in EECP-treated animals. Our results clearly evidence for the first time that C. paniculatus seed extract inhibits lead-acetate-induced detrimental changes in kidneys by regulating PI3K/AKT signaling pathways.

The Role of Insulin-like Growth Factor-1 (IGF-1) in the Control of Neuroendocrine Regulation of Growth

In mammals, the neuroendocrine system, which includes the communication between the hypothalamus and the pituitary, plays a major role in controlling body growth and cellular metabolism. GH produced from the pituitary somatotroph is considered the master regulator of somatic development and involved, directly and indirectly, in carbohydrate and lipid metabolism via complex, yet well-defined, signaling pathways. GH production from the pituitary gland is primarily regulated by the counter-regulatory effects of the hypothalamic GHRH and SST hormones. The role of IGF-1 feedback regulation in GH production has been demonstrated by pharmacologic interventions and in genetically modified mouse models. In the present review, we discuss the role of IGF-1 in the regulation of the GH-axis as it controls somatic growth and metabolic homeostasis. We present genetically modified mouse models that maintain the integrity of the GH/GHRH-axis with the single exception of IGF-1 receptor (IGF-1R) deficiency in the hypothalamic GHRH neurons and somatotroph that reveals a novel mechanism controlling adipose tissues physiology and energy expenditure.

Cancer and diabetes: the interlinking metabolic pathways and repurposing actions of antidiabetic drugs

Cancers are regarded as one of the main causes of death and result in high health burden worldwide. The management of cancer include chemotherapy, surgery and radiotherapy. The chemotherapy, which involves the use of chemical agents with cytotoxic actions is utilised as a single treatment or combined treatment. However, these managements of cancer such as chemotherapy poses some setbacks such as cytotoxicity on normal cells and the problem of anticancer drug resistance. Therefore, the use of other therapeutic agents such as antidiabetic drugs is one of the alternative interventions used in addressing some of the limitations in the use of anticancer agents. Antidiabetic drugs such as sulfonylureas, biguanides and thiazolidinediones showed beneficial and repurposing actions in the management of cancer, thus, the activities of these drugs against cancer is attributed to some of the metabolic links between the two disorders and these includes hyperglycaemia, hyperinsulinemia, inflammation, and oxidative stress as well as obesity. Furthermore, some studies showed that the use of antidiabetic drugs could serve as risk factors for the development of cancerous cells particularly pancreatic cancer. However, the beneficial role of these chemical agents overweighs their detrimental actions in cancer management. Hence, the present review indicates the metabolic links between cancer and diabetes and the mechanistic actions of antidiabetic drugs in the management of cancers.

Glucocorticoid receptor triggers a reversible drug-tolerant dormancy state with acquired therapeutic vulnerabilities in lung cancer

The glucocorticoid receptor (GR) regulates gene expression, governing aspects of homeostasis, but is also involved in cancer. Pharmacological GR activation is frequently used to alleviate therapy-related side-effects. While prior studies have shown GR activation might also have anti-proliferative action on tumours, the underpinnings of glucocorticoid action and its direct effectors in non-lymphoid solid cancers remain elusive. Here, we study the mechanisms of glucocorticoid response, focusing on lung cancer. We show that GR activation induces reversible cancer cell dormancy characterised by anticancer drug tolerance, and activation of growth factor survival signalling accompanied by vulnerability to inhibitors. GR-induced dormancy is dependent on a single GR-target gene, CDKN1C, regulated through chromatin looping of a GR-occupied upstream distal enhancer in a SWI/SNF-dependent fashion. These insights illustrate the importance of GR signalling in non-lymphoid solid cancer biology, particularly in lung cancer, and warrant caution for use of glucocorticoids in treatment of anticancer therapy related side-effects.

Evaluation of chemo-preventive efficacy of Ficus religiosa latex extract by flow cytometry analysis and gene expression studies performed by RT-PCR in various cell lines

Background

An extract of Ficus religiosa latex has been previously found to possess potent pharmacological activity with high antioxidant content phytochemical. The present research was conducted to investigate the chemo-preventive efficacy of latex extract on human breast adenocarcinoma MDA MB 231, human neroblastoma IMR 32, and human colorectal HCT 116 cell lines.

Results

The results showed that the latex crude extract induced cytotoxicity in all the selected cell lines with IC50 value 4.8 ± 1.13 μg/ml against the IMR 32 cell line. The cell cycle analysis results indicated the arrest and accumulation of cells at G1 phase in case of MDA MB 231 cells and HCT 116 cells whereas in the case of IMR 32 cells the arrest was in G2/M phase. The clear bands of fragments observed in DNA ladder experiments showed that apoptosis is induced by extracts in the cell lines. This could be correlated with the gene level expression studies on selected pro-apoptotic (p53 and caspase-3) and anti-apoptotic (Bcl-2, AKT) genes, which got upregulated and downregulated, respectively.

Conclusion

Based on the experimental evidence, Ficus religiosa contains phytochemicals with potent antitumor activities.

TrkC Is Essential for Nephron Function and Trans-Activates Igf1R Signaling

BACKGROUND

Injury to kidney podocytes often results in chronic glomerular disease and consecutive nephron malfunction. For most glomerular diseases, targeted therapies are lacking. Thus, it is important to identify novel signaling pathways contributing to glomerular disease. Neurotrophic tyrosine kinase receptor 3 (TrkC) is expressed in podocytes and the protein transmits signals to the podocyte actin cytoskeleton.

METHODS

Nephron-specific TrkC knockout (TrkC-KO) and nephron-specific TrkC-overexpressing (TrkC-OE) mice were generated to dissect the role of TrkC in nephron development and maintenance.

RESULTS

Both TrkC-KO and TrkC-OE mice exhibited enlarged glomeruli, mesangial proliferation, basement membrane thickening, albuminuria, podocyte loss, and aspects of FSGS during aging. Igf1 receptor (Igf1R)-associated gene expression was dysregulated in TrkC-KO mouse glomeruli. Phosphoproteins associated with insulin, erb-b2 receptor tyrosine kinase (Erbb), and Toll-like receptor signaling were enriched in lysates of podocytes treated with the TrkC ligand neurotrophin-3 (Nt-3). Activation of TrkC by Nt-3 resulted in phosphorylation of the Igf1R on activating tyrosine residues in podocytes. Igf1R phosphorylation was increased in TrkC-OE mouse kidneys while it was decreased in TrkC-KO kidneys. Furthermore, TrkC expression was elevated in glomerular tissue of patients with diabetic kidney disease compared with control glomerular tissue.

CONCLUSIONS

Our results show that TrkC is essential for maintaining glomerular integrity. Furthermore, TrkC modulates Igf-related signaling in podocytes.

PI3K Catalytic Subunits α and β Modulate Cell Death and IL-6 Secretion Induced by Talc Particles in Human Lung Carcinoma Cells

Hydrated magnesium silicate (or "talc" particles) is a sclerosis agent commonly used in the management of malignant pleural effusions, a common symptom of metastatic diseases, including lung cancers. However, the direct effects of talc particles to lung carcinoma cells, which can be found in the malignant pleural effusion fluids from patients with lung cancer, are not fully understood. Here, we report a study of the signaling pathways that can modulate the cell death and IL-6 secretion induced by talc particles in human lung carcinoma cells. We found that talc-sensitive cells have higher mRNA and protein expression of PI3K catalytic subunits α and β. Further experiments confirmed that modulation (inhibition or activation) of the PI3K pathway reduces or enhances cellular sensitivity to talc particles, respectively, independent of the inflammasome. By knocking down specific PI3K isoforms, we also confirmed that both PI3Kα and -β mediate the observed talc effects. Our results suggest a novel role of the PI3K pathway in talc-induced cell death and IL-6 secretion in lung carcinoma cells. These cellular events are known to drive fibrosis, and thus further studies of the PI3K pathway may provide a better understanding of the mechanisms of talc sclerosis in the malignant pleural space.

PI3Kinase-p110δ Overexpression Impairs Dendritic Morphogenesis and Increases Dendritic Spine Density

Activity and expression of the phosphoinositide 3-kinase (PI3K) catalytic isoform, PIK3CD/p110δ, is increased in schizophrenia, autism, and intellectual delay and pro-cognitive preclinical efficacy of p110δ-inhibition has been demonstrated in pharmacological, genetic, and developmental rodent models of psychiatric disorders. Although PI3K signaling has been implicated in the development and function of neurons and glia; isoform-specific roles of the individual PI3Ks are less clear and the biological effects of increased p110δ on neuronal development are unknown. Since the pathobiological direction of p110δ changes in neurodevelopmental disorders are increased expression and activity, we hypothesized that overexpression of p110δ would impact measures of neuronal development and maturation relevant to connectivity and synaptic transmission. p110δ overexpression in primary rat hippocampal cultures significantly reduced dendritic morphogenesis and arborization and increased immature and mature dendritic spine densities, without impacting cell viability, soma size, or axon length. Together, our novel findings demonstrate the importance of homeostatic regulation of the p110δ isoform for normative neuronal development and highlight a potential pathophysiological mechanism of association to disorders of neurodevelopment.

Cracking the context-specific PI3K signaling code

Specificity in signal transduction is determined by the ability of cells to "encode" and subsequently "decode" different environmental signals. Akin to computer software, this "signaling code" governs context-dependent execution of cellular programs through modulation of signaling dynamics and can be corrupted by disease-causing mutations. Class IA phosphoinositide 3-kinase (PI3K) signaling is critical for normal growth and development and is dysregulated in human disorders such as benign overgrowth syndromes, cancer, primary immune deficiency, and metabolic syndrome. Despite decades of PI3K research, understanding of context-dependent regulation of the PI3K pathway and of the underlying signaling code remains rudimentary. Here, we review current knowledge on context-specific PI3K signaling and how technological advances now make it possible to move from a qualitative to quantitative understanding of this pathway. Insight into how cellular PI3K signaling is encoded or decoded may open new avenues for rational pharmacological targeting of PI3K-associated diseases. The principles of PI3K context-dependent signal encoding and decoding described here are likely applicable to most, if not all, major cell signaling pathways.

Combination therapy of gefitinib and miR-30a-5p may overcome acquired drug resistance through regulating the PI3K/AKT pathway in non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) patients with an epidermal growth factor receptor (EGFR) mutation often initially respond to EGFR tyrosine kinase inhibitor (EGFR-TKI) treatment but may acquire drug resistance due to multiple factors. MicroRNAs are a class of small noncoding and endogenous RNA molecules that may play a role in overcoming the resistance.

MATERIALS AND METHODS

In this study, we explored and validated, through in vitro experiments and in vivo models, the ability of a combination treatment of EGFR-TKI, namely gefitinib, and a microRNA mimic, miR-30a-5p, to overcome drug resistance through regulation of the insulin-like growth factor receptor-1 (IGF1R) and hepatocyte growth factor receptor signaling pathways, which all converge on phosphatidylinositol 3 kinase (PI3K), in NSCLC. First, we examined the hypothesized mechanisms of drug resistance in H1650, H1650-acquired gefitinib-resistance (H1650GR), H1975, and H460 cell lines. Next, we investigated a potential combination treatment approach to overcome acquired drug resistance in the H1650GR cell line and an H1650GR cell implanted mouse model.

RESULTS

Dual inhibitors of EGFR and IGF1R significantly lowered the expression levels of phosphorylated protein kinase B (p-AKT) and phosphorylated mitogen-activated protein kinase (p-ERK) compared with the control group in all cell lines. With the ability to repress PI3K expression, miR-30a-5p mimics induced cell apoptosis, and inhibited cell invasion and migration in the treated H1650GR cell line.

CONCLUSION

Gefitinib, combined with miR-30a-5p mimics, effectively suppressed the growth of H1650GR-induced tumor in xenografts. Hence, a combination therapy of gefitinib and miR-30a-5p may play a critical role in overcoming acquired resistance to EGFR-TKIs. The reviews of this paper are available via the supplemental material section.

Insulin-Like Growth Factor Binding Protein-5 in Physiology and Disease

Insulin-like growth factor (IGF) signaling is regulated by a conserved family of IGF binding proteins (IGFBPs) in vertebrates. Among the six distinct types of IGFBPs, IGFBP-5 is the most highly conserved across species and has the broadest range of biological activities. IGFBP-5 is expressed in diverse cell types, and its expression level is regulated by a variety of signaling pathways in different contexts. IGFBP-5 can exert a range of biological actions including prolonging the half-life of IGFs in the circulation, inhibition of IGF signaling by competing with the IGF-1 receptor for ligand binding, concentrating IGFs in certain cells and tissues, and potentiation of IGF signaling by delivery of IGFs to the IGF-1 receptor. IGFBP-5 also has IGF-independent activities and is even detected in the nucleus. Its broad biological activities make IGFBP-5 an excellent representative for understanding IGFBP functions. Despite its evolutionary conservation and numerous biological activities, knockout of IGFBP-5 in mice produced only a negligible phenotype. Recent research has begun to explain this paradox by demonstrating cell type-specific and physiological/pathological context-dependent roles for IGFBP-5. In this review, we survey and discuss what is currently known about IGFBP-5 in normal physiology and human disease. Based on recent in vivo genetic evidence, we suggest that IGFBP-5 is a multifunctional protein with the ability to act as a molecular switch to conditionally regulate IGF signaling.

PYP1-4 peptide from Pyropia yezoensis protects against acetaminophen-induced hepatotoxicity in HepG2 cells

Acetaminophen (APAP) is a widely used analgesic and antipyretic. It is safe at normal treatment doses; however, APAP overdose is a major cause of acute liver and kidney failure. A variety of methods to reduce the damage caused by APAP overdose have previously been evaluated. The protein-rich seaweed Pyropia yezoensis has antioxidant, antitumor and anti-inflammatory activities, and protects against cytotoxicity. However, little is known regarding the protective effects of P. yezoensis peptide against APAP-induced hepatotoxicity. The present study investigated the ability of P. yezoensis peptide (PYP1-4) to ameliorate the damage caused by APAP-induced hepatotoxicity using HepG2 as the model cell line in addition to the signaling pathways involved. Briefly, cell viability, nitric oxide, reactive oxygen species and apoptosis assays were performed in conjunction with western blot analysis and reverse transcription-quantitative PCR. First, the present study revealed the minimum toxic concentration of APAP (15 mM) and the resting concentration of PYP1-4 (0–500 ng/ml). Administration of PYP1-4 to APAP-induced cells decreased the nitric oxide and reactive oxygen species levels, and restored the levels of antioxidant-associated proteins (catalase, heme oxygenase 1, superoxide dismutase 2 and quinone oxidoreductase 1). PYP1-4 increased the translocation of nuclear factor, erythroid 2 like 2 to the nucleus and the activities of glycogen synthase kinase-3β, Akt and AMP-activated protein kinase. In addition, APAP induced apoptosis; however, PYP1-4 inhibited apoptosis by modulating the levels of pro-apoptotic markers (Bad), anti-apoptotic markers (Bcl-2 and BH3 interacting domain death agonist), caspases and poly (ADP-ribose) polymerase 1. Subsequently, the insulin-like growth factor 1 receptor signaling pathway was investigated to determine whether PYP1-4 treatment restored the levels of cell growth-associated factors during APAP-induced hepatotoxicity. PYP1-4 treatment impacted the levels of components of the insulin receptor substrate 1/PI3K/Akt and Ras/Raf/ERK signaling pathways, and promoted cell survival. Therefore, the P. yezoensis peptide PYP1-4 may be useful for preventing APAP-induced hepatotoxicity.

Unravelling the insulin-like growth factor I-mediated photoprotection of the skin

Chronic exposure of human skin to solar ultraviolet radiation (UVR) induces a range of biological reactions which may directly or indirectly lead to the development of skin cancer. In order to overcome these damaging effects of UVR and to reduce photodamage, the skin's endogenous defence system functions in concert with the various exogenous photoprotectors. Growth factors, particularly insulin-like growth factor-I (IGF-I), produced within the body as a result of cellular interaction in response to UVR demonstrates photoprotective properties in human skin. This review summarises the impact of UVR-induced photolesions on human skin, discusses various endogenous as well as exogenous approaches of photoprotection described to date and explains how IGF-I mediates UVR photoprotective responses at the cellular and mitochondrial level. Further, we describe the current interventions using growth factors and propose how the knowledge of the IGF-I photoprotection signalling cascades may direct the development of improved UVR protection and remedial strategies.

Nimodipine-Dependent Protection of Schwann Cells, Astrocytes and Neuronal Cells from Osmotic, Oxidative and Heat Stress Is Associated with the Activation of AKT and CREB

Clinical and experimental data assumed a neuroprotective effect of the calcium channel blocker nimodipine. However, it has not been proven which neuronal or glial cell types are affected by nimodipine and which mechanisms underlie these neuroprotective effects. Therefore, the aim of this study was to investigate the influence of nimodipine treatment on the in vitro neurotoxicity of different cell types in various stress models and to identify the associated molecular mechanisms. Therefore, cell lines from Schwann cells, neuronal cells and astrocytes were pretreated for 24 h with nimodipine and incubated under stress conditions such as osmotic, oxidative and heat stress. The cytotoxicity was measured via the lactate dehydrogenase (LDH) activity of cell culture supernatant. As a result, the nimodipine treatment led to a statistically significantly reduced cytotoxicity in Schwann cells and neurons during osmotic (p ≤ 0.01), oxidative (p ≤ 0.001) and heat stress (p ≤ 0.05), when compared to the vehicle. The cytotoxicity of astrocytes was nimodipine-dependently reduced during osmotic (p ≤ 0.01), oxidative (p ≤ 0.001) and heat stress (not significant). Moreover, a decreased caspase activity as well as an increased proteinkinase B (AKT) and cyclic adenosine monophosphate response element-binding protein (CREB) phosphorylation could be observed after the nimodipine treatment under different stress conditions. These results demonstrate a cell type-independent neuroprotective effect of the prophylactic nimodipine treatment, which is associated with the prevention of stress-dependent apoptosis through the activation of CREB and AKT signaling pathways and the reduction of caspase 3 activity.

Chaperone-mediated autophagy degradation of IGF-1Rβ induced by NVP-AUY922 in pancreatic cancer

Enhancement of insulin-like growth factor 1 receptor (IGF-IR) degradation by heat shock protein 90 (HSP90) inhibitor is a potential antitumor therapeutic strategy. However, very little is known about how IGF-IR protein levels are degraded by HSP90 inhibitors in pancreatic cancer (PC). We found that the HSP90α inhibitor NVP-AUY922 (922) effectively downregulated and destabilized the IGF-1Rβ protein, substantially reduced the levels of downstream signaling molecules (p-AKT, AKT and p-ERK1/2), and resulted in growth inhibition and apoptosis in IGF-1Rβ-overexpressing PC cells. Preincubation with a proteasome or lysosome inhibitor (MG132, 3 MA or CQ) mainly led to IGF-1Rβ degradation via the lysosome degradation pathway, rather than the proteasome-dependent pathway, after PC cells were treated with 922 for 24 h. These results might be associated with the inhibition of pancreatic cellular chymotrypsin-peptidase activity by 922 for 24 h. Interestingly, 922 induced autophagic flux by increasing LC3II expression and puncta formation. However, knockdown of the crucial autophagy component AGT5 and the chemical inhibitor 3 MA-blocked 922-induced autophagy did not abrogate 922-triggered IGF-1Rβ degradation. Furthermore, 922 could enhance chaperone-mediated autophagy (CMA) activity and promote the association between HSP/HSC70 and IGF-1Rβ or LAMP2A in coimmunoprecipitation and immunofluorescence analyses. Silencing of LAMP2A to inhibit CMA activity reversed 922-induced IGF-1Rβ degradation, suggesting that IGF-1Rβ degradation by 922 was partially dependent on the CMA pathway rather than macroautophagy. This finding is mirrored by the identification of the KFERQ-like motif in IGF-1Rβ. These observations support the potential application of 922 for IGF-1Rβ-overexpressing PC therapy and first identify the role of the CMA pathway in IGF-1Rβ degradation by an HSP90 inhibitor.

Antitumor effect of insulin-like growth factor-1 receptor inhibition in head and neck squamous cell carcinoma

OBJECTIVES

The insulin-like growth factor-1 receptor (IGF1R) has been implicated in therapeutic resistance in head and neck squamous cell carcinoma (HNSCC), and small molecule tyrosine kinase inhibitors (TKIs) of IGF1R activity may have anticancer activity. Therefore, the relationship between survival and IGF1R expression was assessed for oral cavity (OC) cancer, and the antitumor effects of two IGF1R-TKIs, OSI-906 and BMS-754807, were evaluated in HNSCC cell lines in vitro.

METHODS

Clinical outcome data and tissue microarray immunohistochemistry were used to generate IGF1R expression-specific survival curves. Immunoblot, alamarBlue proliferation assay, trypan blue exclusion viability test, clonogenic assay, flow cytometry, and reverse phase protein array (RPPA) were used to evaluate in vitro responses to IGF1R-TKIs.

RESULTS

For patients with stage III/IV OCSCC, higher IGF1R expression was associated with poorer overall 5-year survival (P = 0.029). Both BMS-754807 and OSI-906 caused dose-dependent inhibition of IGF1R and Akt phosphorylation and inhibited proliferation; BMS-754807 was more potent than OSI-906. Both drugs reduced HNSCC cell viability; only OSI-906 was able to eliminate all viable cells at 10 μM. The two drugs similarly inhibited clonogenic cell survival. At 1 μM, only BMS-754807 caused a fourfold increase in the basal apoptotic rate. RPPA demonstrated broad effects of both drugs on canonical IGF1R signaling pathways and also inhibition of human epidermal growth factor receptor-3 (HER3), Src, paxillin, and ezrin phosphorylation.

CONCLUSION

OSI-906 and BMS-754807 inhibit IGF1R activity in HNSCC cell lines with reduction in prosurvival and proliferative signaling and with concomitant antiproliferative and proapoptotic effects. Such antagonists may have utility as adjuvants to existing therapies for HNSCC.

LEVEL OF EVIDENCE

NA Laryngoscope, 130:1470-1478, 2020.

pik3r3b, a novel immune-related gene in Nile tilapia (Oreochromis niloticus): Identification, expression and analysis of antibacterial activity

A full-length cDNA encoding phosphatidylinositol 3-kinase regulatory subunit gamma b gene in Nile tilapia (Oreochromis niloticus), termed as On-pik3r3b, was identified and characterized in this study. The sequence analysis demonstrated that the full-length cDNA of On-pik3r3b was 2018 bp, containing a 5' untranslated region (UTR) of 171 bp, an open reading frame (ORF) of 1422 bp and a 3' UTR of 425 bp. Its protein sequence displayed a high degree of identity with other fish. Using qPCR, the expression patterns of On-pik3r3b were investigated. In healthy Nile tilapia, the transcripts of On-pik3r3b were detected in all examined tissues, except the skin. Upon the stimulation with Streptococcus agalactiae, the On-pik3r3b expression level in liver, spleen, kidney and gill were significantly increased at 12 h after infection. The recombinant On-pik3r3b showed in vitro antibacterial activity, against S. agalactiae and E. coli. Our observation strongly indicates that On-pik3r3b is involved in the innate immune response in Nile tilapia.

Sequential testicular atrophy involves changes in cellular proliferation and apoptosis associated with variations in aromatase P450 expression levels in Irs-2-deficient mice

Insulin receptor substrate 2 (Irs-2) is an intracellular protein susceptible to phosphorylation after activation of the insulin receptor. Its suppression affects testis development and its absence induces peripheral resistance to insulin. The aim of this study was to identify changes induced by the deletion of Irs-2 in the testicular structure and by the altered expression of cytochrome P450 aromatase, a protein necessary for the development and maturation of germ cells. Adult knockout (KO) mice (Irs-2^-/- , 6 and 12 weeks old) and age-matched wild-type (WT) mice were used in this study. Immunohistochemistry and Western blot analyses were performed to study proliferation (PCNA), apoptosis (active caspase-3) and P450 aromatase expression in testicular histological sections. Deletion of Irs-2 decreased the number of epithelial cells in the seminiferous tubule and rete testis. Aberrant cells were frequently detected in the epithelia of Irs-2^-/- mice, accompanied by variations in spermatogonia, which were shown to exhibit small hyperchromatic nuclei as well as polynuclear and anuclear structures. The amount of cell proliferation was significantly lower in Irs-2^-/- mice than in WT mice, whereas apoptotic processes were more common in Irs-2^-/- mice. Aromatase P450 reactivity was higher in 6-week-old KO mice than in WT mice of the same age and was even higher at 12 weeks. Our results suggest that Irs-2 is a key element in spermatogenesis because silencing Irs-2 induces the sequential development of testicular atrophy. The effects are observed mainly in germ cells present in the seminiferous tubule, which may be due to changes in cytochrome P450 aromatase expression.

Dibenzoxanthenes induce apoptosis and autophagy in HeLa cells by modeling the PI3K/Akt pathway

A new series of dibenzoxanthene derivatives 4a-4d (4a: 1-oxo-5-bromo-11-cyano-13c-methoxy-1,13c-dihydroxyl-dibenzo[a,kl]xanthene, 4b: 1-oxo-5-bromo-11-cyano-13c-ethoxy-1,13c-dihydroxyl-dibenzo[a,kl]xanthene, 4c: 1-oxo-5-bromo-11-cyano-13c-propoxy-1,13c-dihydroxyl-dibenzo[a,kl]xanthene and 4d: 1-oxo-5-bromo-11-cyano-13c-butoxy-1,13c-dihydroxyl-dibenzo[a,kl]xanthene) were synthesized and the molecular mechanisms of anti-cancer activities were investigated. These compounds showed excellent anti-tumor activity against A549, Eca-109, HeLa, HepG2 and SGC-7901 cell lines. Compounds 4a-4d could effectively inhibit the migration and invasion of HeLa cells in wound healing and transwell assays. Compounds induced the DNA damage and arrested in cell cycle distribution at G0/G1 phase. Apoptosis induced by compounds was detected using morphological observation of nuclear changes and FITC-Annexin V/PI staining. Additionally, compounds also induced the autophagy of HeLa cells through observing AO staining and upregulated the expression of LC3II and Beclin-1 proteins. Furthermore, treatment with autophagy inhibitor 3-methyladenine induced an obvious decrease in apoptotic rate in HeLa cells. This indicated that autophagy further promoted the HeLa cells apoptosis. Compounds 4a-4d enhanced the intracellular Ca²⁺ and ROS. Then the mitochondrial membrane potential of HeLa cells was depolarized and the cytochrome C was released from mitochondria into cytoplasm. Activities of the apoptotic factors Bcl-2, Bax, caspase-3 were measured using western blotting. After HeLa cells were exposed to compounds, the expressions of PI3K and Akt protein were decreased. Compounds exhibit anti-cancer activity via apoptosis and autophagy through inhibition of PI3K/Akt signaling pathway in HeLa cells.

Altered muscarinic receptor expression in the cerebral cortex of epileptic rats: restorative role of Withania somnifera

Temporal lobe epilepsy involves a sequence of events that can lead to neurotransmitter signalling alterations. There are many herbal extracts considered to be alternative therapeutic methods to manage epilepsy. In this study, we investigated the effect of Withania somnifera (WS) root extract and withanolide A (WA) in the management of temporal lobe epilepsy. Confocal imaging of TOPRO-3-stained cortical sections showed severe damage in the epileptic brain. We also observed a reduced antioxidant potential and increased peroxide levels in the epileptic test group of rats. Oxidative stress resulted in the down-regulation of CREB, NF-κB, and TNF-α, and with up-regulation of the apoptotic factors caspases 8 and 3 and Bax in the epileptic group. Epileptic condition also resulted in increased muscarinic receptor binding and mRNA expression in the cerebral cortex. Withania somnifera and withanolide A significantly reversed the altered muscarinic receptor expression and reversed the oxidative stress and resultant derailment in cell signalling. Thus our studies suggest that Withania somnifera and withanolide A play important roles in central muscarinic receptor functional balance and activation of the antioxidant system in the cerebral cortex in temporal lobe epilepsy. These findings can be of immense therapeutic significance for managing epilepsy.

Role of PI3K/Akt/NF-κB and GSK-3β pathways in the rat model of cardiopulmonary bypass-related lung injury

BACKGROUND

Apoptosis is a cellular mechanism contributing to cardiac surgery using cardiopulmonary bypass (CPB)-induced lung injury. The ubiquitous PI3K/Akt pathway regulates proliferation, apoptosis and differentiation by controlling a broad range of target proteins including NF-κB and GSK-3β. The roles of the PI3K/Akt/NF-κB and PI3K/Akt/GSK-3β pathways in CPB-related lung injury are unclear.

METHODS

Seventy-two male Sprague-Dawley rats were assigned into sham, CPB, Wortmannin (Wtn) and insulin-like growth factor-I (IGF-I) groups (n = 18, each). Six subjects per group were evaluated at each of three time points: Prior to CPB (T1); opening of the left hilus pulmonis (T2); and 90 min after CPB (T3). Arterial blood specimens were obtained at each time point to test respiratory and oxygenation indices. Left lung tissues were processed for H&E and TUNEL staining. Western blot was employed to evaluate protein levels and activities of Akt, phospho-Akt (p-Akt), GSK-3β, phospho-GSK-3β (p-GSK-3β) and nuclear NF-κB.

RESULTS

Lung ischemia/reperfusion and CPB caused notable lung injury, as evidenced by lung functional decline and pathological deterioration, accompanied by increases in apoptosis and expression levels of p-Akt, p-GSK-3β and nuclear NF-κB in lungs (all P < 0.05 vs. Sham). At T3, Wtn-treated CPB subjects showed worsened lung function and pathological lung structures, as well as apoptosis in lungs (all P < 0.05 vs. CPB); additionally, Wtn inhibited Akt phosphorylation and slightly, but significantly increased expression of nuclear NF-κB (both P < 0.001 vs. CPB). Conversely, treatment of subjects with IGF-I increased Akt phosphorylation (P < 0.001 vs. CPB), inhibited expression of nuclear NF-κB (P = 0.008 vs. CPB), improved lung function and tissue morphology (both P < 0.05 vs. CPB), and reduced apoptosis in lungs (P < 0.001 vs. CPB). Neither Wtn nor IGF-I did alter GSK-3β phosphorylation levels (P =  0.836 and P =  0.669 vs. CPB, respectively).

CONCLUSION

The PI3K/Akt/NF-κB pathway played a role in CPB-related lung injury, possibly through mediating apoptosis in lungs. GSK-3β, a signaling effector that also participated in CPB-induced apoptosis in lungs, but was not regulated by the PI3K/Akt pathway in this context.

Insulin-Like Growth Factor-1 Signaling in Lung Development and Inflammatory Lung Diseases

Insulin-like growth factor-1 (IGF-1) was firstly identified as a hormone that mediates the biological effects of growth hormone. Accumulating data have indicated the role of IGF-1 signaling pathway in lung development and diseases such as congenital disorders, cancers, inflammation, and fibrosis. IGF-1 signaling modulates the development and differentiation of many types of lung cells, including airway basal cells, club cells, alveolar epithelial cells, and fibroblasts. IGF-1 signaling deficiency results in alveolar hyperplasia in humans and disrupted lung architecture in animal models. The components of IGF-1 signaling pathways are potentiated as biomarkers as they are dysregulated locally or systemically in lung diseases, whereas data may be inconsistent or even paradoxical among different studies. The usage of IGF-1-based therapeutic agents urges for more researches in developmental disorders and inflammatory lung diseases, as the majority of current data are collected from limited number of animal experiments and are generally less exuberant than those in lung cancer. Elucidation of these questions by further bench-to-bedside researches may provide us with rational clinical diagnostic approaches and agents concerning IGF-1 signaling in lung diseases.

Obesity and Cancer: Existing and New Hypotheses for a Causal Connection

Existing explanations of obesity-associated cancer emphasise direct mutagenic effects of dietary components or hormonal imbalance. Some of these hypotheses are reviewed briefly, but recent evidence suggests a major role for chronic inflammation in cancer risk, possibly involving dietary content. These ideas include the inflammation-induced activation of the kynurenine pathway and its role in feeding and metabolism by activation of the aryl hydrocarbon receptor (AHR) and by modulating synaptic transmission in the brain. Evidence for a role of the kynurenine pathway in carcinogenesis then provides a potentially major link between obesity and cancer. A second new hypothesis is based on evidence that serine proteases can deplete cells of the tumour suppressors Deleted in Colorectal Cancer (DCC) and neogenin. These enzymes include mammalian chymotryptic proteases released by pro-inflammatory neutrophils and macrophages. Blood levels of chymotrypsin itself increase in parallel with food intake. The mechanistically similar bacterial enzyme subtilisin is widespread in the environment, animal probiotics, meat processing and cleaning products. Simple public health schemes in these areas, with selective serine protease inhibitors and AHR antagonists and could prevent a range of intestinal and other cancers.

Effects of chondroitin sulfate proteoglycan 4 (NG2/CSPG4) on soft-tissue sarcoma growth depend on tumor developmental stage

Sarcomas, and the mesenchymal precursor cells from which they arise, express chondroitin sulfate proteoglycan 4 (NG2/CSPG4). However, NG2/CSPG4's function and its capacity to serve as a therapeutic target in this tumor type are unknown. Here, we used cells from human tumors and a genetically engineered autochthonous mouse model of soft-tissue sarcomas (STSs) to determine NG2/CSPG4's role in STS initiation and growth. Inhibiting NG2/CSPG4 expression in established murine and human STSs decreased tumor volume by almost two-thirds and cell proliferation rate by 50%. NG2/CSPG4 antibody immunotherapy in human sarcomas established as xenografts in mice similarly decreased tumor volume, and expression of a lentivirus blocking NG2/CSPG4 expression inhibited tumor cell proliferation and increased the latency of engraftment. Gene profiling showed that Ng2/Cspg4 deletion altered the expression of genes regulating cell proliferation and apoptosis. Surprisingly, Ng2/Cspg4 deletion at the time of tumor initiation resulted in larger tumors. Gene expression profiling indicated substantial down-regulation of insulin-like growth factor binding protein (Igfbp) genes when Ng2/Cspg4 is depleted at tumor initiation, but not when Ng2/Cspg4 is depleted after tumor initiation. Such differences may have clinical significance, as therapeutic targeting of a signaling pathway such as NG2/CSPG4 may have different effects on cell behavior with tumor progression. NG2/CSPG4 depletion has divergent effects, depending on the developmental stage of sarcoma. In established tumors, IGF signaling is active, and NG2 inhibition targets cell proliferation and apoptosis.

Physiologic Growth Hormone-Replacement Therapy and Craniopharyngioma Recurrence in Pediatric Patients: A Meta-Analysis

OBJECTIVE

A systematic review and meta-analysis were conducted to examine the effect of growth hormone-replacement therapy (GHRT) on the recurrence of craniopharyngioma in children.

METHODS

PubMed, Embase, and Cochrane databases were searched through April 2017 for studies that evaluated the effect of GHRT on the recurrence of pediatric craniopharyngioma. Pooled effect estimates were calculated with fixed- and random-effects models.

RESULTS

Ten studies (n = 3487 patients) met all inclusion criteria, including 2 retrospective cohorts and 8 case series. Overall, 3436 pediatric patients were treated with GHRT after surgery and 51 were not. Using the fixed effect model, we found that the overall craniopharyngioma recurrence rate was lower among children who were treated by GHRT (10.9%; 95% confidence interval 9.80%-12.1%; I² = 89.1%; P for heterogeneity <0.01; n = 10 groups) compared with those who were not (35.2%; 95% confidence interval 23.1%-49.6%; I² = 61.7%; P for heterogeneity = 0.11; n = 3); the P value comparing the 2 groups was <0.01. Among patients who were treated with GHRT, subgroup analysis revealed that there was a greater prevalence of craniopharyngioma recurrence among studies conducted outside the United States (P < 0.01), single-center studies (P < 0.01), lower impact factor studies (P = 0.03), or studies with a lower quality rating (P = 0.01). Using the random-effects model, we found that the results were not materially different except for when stratifying by GHRT, impact factor, or study quality; this led to nonsignificant differences. Both Begg's rank correlation test (P = 0.7) and Egger's linear regression test (P = 0.06) indicated no publication bias.

CONCLUSIONS

This meta-analysis demonstrated a lower recurrence rate of craniopharyngioma among children treated with GHRT than those who were not.

Gefitinib (ZD1839) in Previously Treated Advanced Non-Small-Cell Lung Cancer: Experience from a Single Institution

BACKGROUND

We conducted an analysis of gefitinib in patients with advanced non-small-cell lung cancer (NSCLC) to assess the antitumor efficacy of this epidermal growth factor receptor tyrosine kinase inhibitor.

METHODS

Our single-center, prospective landmark analysis included 183 patients with advanced NSCLC who received 250 mg of gefitinib orally once daily in an expanded-use program at our institution. Thirty-three of the 183 patients were previously untreated. The patients included in this analysis had all received at least 12 weeks of gefitinib.

RESULTS

The objective tumor response rate was 3.8%, but an additional 53.5% of patients experienced clinically meaningful disease stabilization. Median progression-free survival time was 3.6 months, and median overall survival time was 8.8 months. The 1-year survival rate for the entire cohort was 35%. Predictors of longer survival included female gender, adenocarcinoma or bronchoalveolar carcinoma histology, and an Eastern Cooperative Oncology Group performance status of 0 or 1. Adverse events were generally mild (grade 1 or 2) and consisted mainly of skin reactions and diarrhea.

CONCLUSIONS

In this single-center experience, gefitinib demonstrated clinically significant antitumor activity and provided good palliation in a predominantly pretreated group of patients. Our results, which are likely to be reproducible in a community setting, demonstrated a 1-year survival rate of 35% in a cohort of patients who were able to take the drug for at least 12 weeks.

Drug delivery approaches for breast cancer

Breast cancer is one of the most common cancers affecting women worldwide. The controlled release of drugs to the precise site of the disease using a nanocarrier vehicle increases the therapeutic efficiency of the drugs. Nanotechnology-based approaches used to endorse clinical improvement from a disease also help to understand the interaction of malignant cells with their microenvironment. Receptor-based targeting is another approach for drug delivery which is undergoing clinical trials. Nanoparticles (NPs) delivery has been proven to promise high loading capacity, less toxicity, and stability of the drugs or biomolecules compared to traditional chemotherapeutic drugs. The goal of this review is to present the current problems of breast cancer therapy and discuss the NP-based targeting to overcome the hurdles of conventional drug therapy approach.

Impaired caudal fin-fold regeneration in zebrafish deficient for the tumor suppressor Pten

Zebrafish are able to completely regrow their caudal fin-folds after amputation. Following injury, wound healing occurs, followed by the formation of a blastema, which produces cells to replace the lost tissue in the final phase of regenerative outgrowth. Here we show that, surprisingly, the phosphatase and tumor suppressor Pten, an antagonist of phosphoinositide-3-kinase (PI3K) signaling, is required for zebrafish caudal fin-fold regeneration. We found that homozygous knock-out mutant (ptena-/-ptenb-/- ) zebrafish embryos, lacking functional Pten, did not regenerate their caudal fin-folds. AKT phosphorylation was enhanced, which is consistent with the function of Pten. Reexpression of Pten, but not catalytically inactive mutant Pten-C124S, rescued regeneration, as did pharmacological inhibition of PI3K. Blastema formation, determined by in situ hybridization for the blastema marker junbb, appeared normal upon caudal fin-fold amputation of ptena-/-ptenb-/- zebrafish embryos. Whole-mount immunohistochemistry using specific markers indicated that proliferation was arrested in embryos lacking functional Pten, and that apoptosis was enhanced. Together, these results suggest a critical role for Pten by limiting PI3K signaling during the regenerative outgrowth phase of zebrafish caudal fin-fold regeneration.

Src Acts as an Effector for Ku70-dependent Suppression of Apoptosis through Phosphorylation of Ku70 at Tyr-530

Src-family tyrosine kinases are widely expressed in many cell types and participate in a variety of signal transduction pathways. Despite the significance of Src in suppression of apoptosis, its mechanism remains poorly understood. Here we show that Src acts as an effector for Ku70-dependent suppression of apoptosis. Inhibition of endogenous Src activity promotes UV-induced apoptosis, which is impaired by Ku70 knockdown. Src phosphorylates Ku70 at Tyr-530, being close to the possible acetylation sites involved in promotion of apoptosis. Src-mediated phosphorylation of Ku70 at Tyr-530 decreases acetylation of Ku70, whereas Src inhibition augments acetylation of Ku70. Importantly, knockdown-rescue experiments with stable Ku70 knockdown cells show that the nonphosphorylatable Y530F mutant of Ku70 reduces the ability of Ku70 to suppress apoptosis accompanied by augmentation of Ku70 acetylation. Our results reveal that Src plays a protective role against hyperactive apoptotic cell death by reducing apoptotic susceptibility through phosphorylation of Ku70 at Tyr-530.

LPIN1 promotes epithelial cell transformation and mammary tumourigenesis via enhancing insulin receptor substrate 1 stability

LPIN1 is a protein that exhibits dual functions as a phosphatidic acid phosphatase enzyme in regulation of triglyceride and glycerophospholipid metabolism and a transcriptional coregulator. Through unknown tumour-promoting mechanism, LPIN1 frequently observed in various human cancer cell lines controls main cellular processes involved in cancer progression. Here, we demonstrate that LPIN1 enhances the tumour-promoting function of insulin receptor substrate 1 (IRS1) by controlling IRS1 stability. LPIN1 interacts with IRS1 in an insulin growth factor-1-dependent signalling pathway and inhibits its serine phosphorylation, and thereby eliminating ubiquitin-dependent degradation of IRS1 via proteasomal and lysosomal pathways. Consequently, LPIN1 overexpression increases IRS1 abundance and enhances IRS1's ability to induce epithelial cell proliferation and mammary tumourigenesis. By contrast, depletion or inhibition of LPIN1 in breast cancer cells leads to a decreased IRS1 level, which subsequently inhibits the RAF1-mediated signalling pathway and AP-1 activity. In the syngeneic 4T1 breast cancer model, LPIN1 overexpression increased tumour development, whereas inhibition of LPIN1 and IRS1 suppressed it. Consistent with these observations, LPIN1 levels were positively correlated with IRS1 expression in human breast cancer. Thus, our results indicate a mechanism by which IRS1 expression is increased in breast cancer, and LPIN1 may be a promising drug target for anticancer therapy.

Neuronal NCX1 overexpression induces stroke resistance while knockout induces vulnerability via Akt

Three different Na⁺/Ca²⁺ exchanger (NCX) isoforms, NCX1, NCX2, and NCX3, are expressed in brain where they play a relevant role in maintaining Na⁺ and Ca²⁺ homeostasis. Although the neuroprotective roles of NCX2 and NCX3 in stroke have been elucidated, the relevance of NCX1 is still unknown because of embryonic lethality of its knocking-out, heart dysfunctions when it is overexpressed, and the lack of selectivity in currently available drugs. To overcome these limitations we generated two conditional genetically modified mice that upon tamoxifen administration showed a selective decrease or increase of NCX1 in cortical and hippocampal neurons. Interestingly, in cortex and hippocampus NCX1 overexpression increased, where NCX1 knock-out reduced, both exchanger activity and Akt1 phosphorylation, a neuronal survival signaling. More important, mice overexpressing NCX1 showed a reduced ischemic volume and an amelioration of focal and general deficits when subjected to transient middle cerebral artery occlusion. Conversely, NCX1-knock-out mice displayed a worsening of brain damage, focal and neurological deficits with a decrease in Akt phosphorylation. These results support the idea that NCX1 overexpression/activation may represent a feasible therapeutic opportunity in stroke intervention.

DJ-1 Expression in Cervical Carcinoma and its Effects on Cell Viability and Apoptosis

Background

This study aimed to investigate the expression of DJ-1 in cervical carcinoma and its effects on cell viability and apoptosis.

Material/Methods

Cervical carcinoma cell line Hela and 85 tissue samples, including 45 primary tumor biopsies, 30 para-carcinoma tissues, and 10 normal cervical tissues samples were used in this study. The expressions of DJ-1 in cervical carcinoma tissue, para-carcinoma tissue, and normal tissue samples were investigated by immunohistochemistry. DJ-1 expression in Hela cells was also investigated by quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. DJ-1 was interfered and transfected with siRNA, then cell viability and apoptosis were assayed by MTT and flow cytometry, respectively. Additionally, the expressions of phosphatase and tensin homolog (PTEN), AKT, and phospho-AKT (P-AKT) were detected.

Results

Immunohistochemistry results showed that DJ-1 was highly expressed in cervical carcinoma tissues. In Hela cells, the expression of DJ-1 was significantly higher than that in normal controls (P<0.05). When cells were treated with DJ-1 siRNA, the cell viability decreased significantly (P<0.05), and the percentage of apoptosis cells increased significantly (P<0.05). In addition, the expressions of PTEN and AKT were significantly higher in the DJ-1 siRNA treatment group than those in the control group (P<0.05). The expression of p-AKT was significantly lower in the DJ-1 siRNA treatment group than in the control group and the DJ-1 over-expression group (P<0.05).

Conclusions

The aberrant up-regulation of DJ-1 expression might be an important step in the pathogenesis of cervical carcinoma.

AKT-induced PKM2 phosphorylation signals for IGF-1-stimulated cancer cell growth

Pyruvate kinase muscle type 2 (PKM2) exhibits post-translational modifications in response to various signals from the tumor microenvironment. Insulin-like growth factor 1 (IGF-1) is a crucial signal in the tumor microenvironment that promotes cell growth and survival in many human cancers. Herein, we report that AKT directly interacts with PKM2 and phosphorylates it at Ser-202, which is essential for the nuclear translocation of PKM2 protein under stimulation of IGF-1. In the nucleus, PKM2 binds to STAT5A and induces IGF-1-stimulated cyclin D1 expression, suggesting that PKM2 acts as an important factor inducing STAT5A activation under IGF-1 signaling. Concordantly, overexpression of STAT5A in cells deficient in PKM2 expression failed to restore IGF-induced growth, whereas reconstitution of PKM2 in PKM2 knockdown cells restored the IGF-induced growth capacity. Our findings suggest a novel role of PKM2 in promoting the growth of cancers with dysregulated IGF/phosphoinositide 3-kinase/AKT signaling.

Irisin ameliorates hepatic glucose/lipid metabolism and enhances cell survival in insulin-resistant human HepG2 cells through adenosine monophosphate-activated protein kinase signaling

Irisin is a newly identified myokine that promotes the browning of white adipose tissue, enhances glucose uptake in skeletal muscle and modulates hepatic metabolism. However, the signaling pathways involved in the effects on hepatic glucose and lipid metabolism have not been resolved. This study aimed to examine the role of irisin in the regulation of hepatic glucose/lipid metabolism and cell survival, and whether adenosine monophosphate-activated protein kinase (AMPK), a master metabolic regulator in the liver, is involved in irisin's actions. Human liver-derived HepG2 cells were cultured in normal glucose-normal insulin (NGNI) or high glucose-high insulin (HGHI/insulin-resistant) condition. Hepatic glucose and lipid metabolism was evaluated by glucose output and glycogen content or triglyceride accumulation assays, respectively. Our results showed that irisin stimulated phosphorylation of AMPK and acetyl-CoA-carboxylase (ACC) via liver kinase B1 (LKB1) rather than Ca(2+)/calmodulin-dependent protein kinase kinase β (CaMKKβ) in HepG2 cells. Irisin ameliorated hepatic insulin resistance induced by HGHI condition. Irisin reduced hepatic triglyceride content and glucose output, but increased glycogen content, with those effects reversed by dorsomorphin, an AMPK inhibitor. Furthermore, irisin also stimulated extracellular signal-regulated kinase (ERK) 1/2 phosphorylation and promoted cell survival in an AMPK-dependent manner. In conclusion, our data indicate that irisin ameliorates dysregulation of hepatic glucose/lipid metabolism and cell death in insulin-resistant states via AMPK activation. These findings reveal a novel irisin-mediated protective mechanism in hepatic metabolism which provides a scientific basis for irisin as a potential therapeutic target for the treatment of insulin resistance and type 2 diabetes mellitus.

Gene Expression and Localization of Insulin-like Growth Factors and Their Receptors throughout Amelogenesis in Rat Incisors

Insulin-like growth factors (IGFs) are expressed in many tissues and control cell differentiation, proliferation, and apoptosis. In teeth, the temporo-spatial pattern of expression IGFs and their receptors has not been fully characterized. The purpose of this study was to obtain a comprehensive profile of their expression throughout the life cycle of ameloblasts, using the continuously erupting rat incisor model. Upper incisors of young male rats were fixed by perfusion, decalcified, and embedded in paraffin. Sections were processed for in situ hybridization and immunohistochemistry. mRNA and protein expression profiles IGF-I, IGF-II, IGF-IR, and IGF-IIR mRNA were essentially identical. At the apical loop of the incisor, very strong signals were seen in the outer enamel epithelium while the inner enamel epithelium showed a moderate reaction. In the region of ameloblasts facing pulp, inner enamel epithelium cells were still moderately reactive while signals over the outer enamel epithelium were slightly reduced. In the region of ameloblasts facing dentin and the initial portion of the secretory zone, signals in ameloblasts were weak while those over the outer enamel epithelium were strong. In the region of postsecretory transition, signals in both ameloblasts and papillary layer cells gradually increased. In maturation proper, signals in ameloblasts appeared as alternating bands of strong and weak reactivities, which corresponded to the regions of ruffle-ended and smooth-ended ameloblasts, respectively. Papillary layer cells also showed alternations in signal intensity that matched those in ameloblasts. These results suggest that the IGF family may act as an autocrine/paracrine system that influences not only cell differentiation but also the physiological activity of ameloblasts.