Phosphoinositide 3-kinase Signaling Research Articles

Targeting Fibroblast Growth Factor Receptor (FGFR) and Phosphoinositide 3-kinase (PI3K) Signaling Pathways in Medulloblastoma Cell Lines.

Medulloblastoma (MB) accounts for ~20% of pediatric malignant central nervous system tumors. Treatment strategies, including surgery, radiation therapy and/or chemotherapy, are effective, but recurrence and metastasis frequently occur. Therefore, novel therapies are required. Herein, the effects of fibroblast growth factor receptor (FGFR) and phosphoinositide 3-kinase (PI3K) inhibitors on MB cells lines were evaluated. MB cell lines (UW228-3, DAOY, Med8a, D425, D283) were tested for sensitivity to FGFR (AZD4547) and PI3K (BEZ235 and BYL719) inhibitors by viability, cytotoxicity, apoptosis, and proliferation assays. Single treatments with FGFR and PI3K inhibitors decreased viability and proliferation in a dose-dependent pattern in most cell lines. Combinination of the two type of drugs, increased sensitivity, especially of the most resistant cell line UW228-3. Combination treatments with FGFR and PI3K inhibitors were superior to single treatments with FGFR and PI3K inhibitors, especially with BEZ235, for MB cell lines.

Activated PI3Kδ breaches multiple B cell tolerance checkpoints and causes autoantibody production.

Antibody-mediated autoimmune diseases are a major health burden. However, our understanding of how self-reactive B cells escape self-tolerance checkpoints to secrete pathogenic autoantibodies remains incomplete. Here, we demonstrate that patients with monogenic immune dysregulation caused by gain-of-function mutations in PIK3CD, encoding the p110δ catalytic subunit of phosphoinositide 3-kinase (PI3K), have highly penetrant secretion of autoreactive IgM antibodies. In mice with the corresponding heterozygous Pik3cd activating mutation, self-reactive B cells exhibit a cell-autonomous subversion of their response to self-antigen: instead of becoming tolerized and repressed from secreting autoantibody, Pik3cd gain-of-function B cells are activated by self-antigen to form plasmablasts that secrete high titers of germline-encoded IgM autoantibody and hypermutating germinal center B cells. However, within the germinal center, peripheral tolerance was still enforced, and there was selection against B cells with high affinity for self-antigen. These data show that the strength of PI3K signaling is a key regulator of pregerminal center B cell self-tolerance and thus represents a druggable pathway to treat antibody-mediated autoimmunity.

Combination of KRAS gene silencing and PI3K inhibition for ovarian cancer treatment

The phosphoinositide 3-kinase (PI3K) and RAS signaling pathways are frequently co-activated and altered during oncogenesis. Owing to their regulatory cross-talk, the early attempts of targeting only one pathway have mostly ended up promoting the development of drug resistance. Here, we propose using small interfering RNA (siRNA) therapeutics to directly target the undruggable KRAS (siKRAS) in combination with the pan-PI3K inhibitor GDC-0941 (GDC) to simultaneously block both PI3K and RAS signaling, thereby exerting synergistic anti-tumor effects on ovarian cancers with PTEN deficiency and KRASG12D mutation. For successful delivery of siKRAS, tGC/psi—nanoparticle formulation of polymerized siRNA and thiol-modified glycol chitosan nanoparticle—was used for KRAS specific inhibition in vitro and in vivo. GDC or siKRAS monotherapy each impede downstream signaling, leading to some delay in cell proliferation and migration. When combined, however, they engender much higher inhibition of PI3K signaling and stimulation of apoptosis in an ovarian allograft model compared to monotherapies. Our results show the feasibility of developing new combination strategies for the management of multiple oncogenic mutations activating PI3K and RAS signaling.

IGF-1-enhanced miR-513a-5p signaling desensitizes glioma cells totemozolomideby targeting the NEDD4L-inhibited Wnt/β-cateninpathway.

Temozolomide (TMZ) is a first-line alkylating agent for glioblastoma multiforme (GBM). Clarifying the mechanisms inducing TMZ insensitivity may be helpful in improving its therapeutic effectiveness against GBM. Insulin-like growth factor (IGF)-1 signaling and micro (mi)RNAs are relevant in mediating GBM progression. However, their roles in desensitizing GBM cells to TMZ are still unclear. We aimed to identify IGF-1-mediated miRNA regulatory networks that elicit TMZ insensitivity for GBM. IGF-1 treatment attenuated TMZ cytotoxicity via WNT/β-catenin signaling, but did not influence glioma cell growth. By miRNA array analyses, 93 upregulated and 148 downregulated miRNAs were identified in IGF-1-treated glioma cells. miR-513a-5p from the miR-513a-2 gene locus was upregulated by IGF-1-mediated phosphoinositide 3-kinase (PI3K) signaling. Its elevated levels were also observed in gliomas versus normal cells, in array data of The Cancer Genome Atlas (TCGA), and the GSE61710, GSE37366, and GSE41032 datasets. In addition, lower levels of neural precursor cell-expressed developmentally downregulated 4-like (NEDD4L), an E3 ubiquitin protein ligase that inhibits WNT signaling, were found in gliomas by analyzing cells, arrays, and RNA sequencing data of TCGA glioma patients. Furthermore, a negative correlation was identified between miR-513a-5p and NEDD4L in glioma. NEDD4L was also validated as a direct target gene of miR-513a-5p, and it was reduced by IGF-1 treatment. Overexpression of NEDD4L inhibited glioma cell viability and reversed IGF-1-repressed TMZ cytotoxicity. In contrast, miR-513a-5p significantly affected NEDD4L-inhibited WNT signaling and reduced TMZ cytotoxicity. These findings demonstrate a distinct role of IGF-1 signaling through miR-513a-5p-inhibited NEDD4L networks in influencing GBM's drug sensitivity to TMZ.

Phosphoinositide 3-Kinase Signaling Can Modulate MHC Class I and II Expression

Molecular events activating the PI3K pathway are frequently detected in human tumors and the activation of PI3K signaling alters numerous cellular processes including tumor cell proliferation, survival, and motility. More recent studies have highlighted the impact of PI3K signaling on the cellular response to interferons and other immunologic processes relevant to antitumor immunity. Given the ability of IFNγ to regulate antigen processing and presentation and the pivotal role of MHC class I (MHCI) and II (MHCII) expression in T-cell-mediated antitumor immunity, we sought to determine the impact of PI3K signaling on MHCI and MHCII induction by IFNγ. We found that the induction of cell surface MHCI and MHCII molecules by IFNγ is enhanced by the clinical grade PI3K inhibitors dactolisib and pictilisib. We also found that PI3K inhibition increases STAT1 protein levels following IFNγ treatment and increases accessibility at genomic STAT1-binding motifs. Conversely, we found that pharmacologic activation of PI3K signaling can repress the induction of MHCI and MHCII molecules by IFNγ, and likewise, the loss of PTEN attenuates the induction of MHCI, MHCII, and STAT1 by IFNγ. Consistent with these in vitro studies, we found that within human head and neck squamous cell carcinomas, intratumoral regions with high phospho-AKT IHC staining had reduced MHCI IHC staining. IMPLICATIONS: Collectively, these findings demonstrate that MHC expression can be modulated by PI3K signaling and suggest that activation of PI3K signaling may promote immune escape via effects on antigen presentation.

Entamoeba histolytica stimulates the alarmin molecule HMGB1 from macrophages to amplify innate host defenses.

Even though Entamoeba histolytica (Eh)-induced host pro-inflammatory responses play a critical role in disease, we know very little about the host factors that regulate this response. Direct contact between host cell and Eh signify the highest level of danger, and to eliminate this threat, the host immune system elicits an augmented immune response. To understand the mechanisms of this response, we investigated the induction and release of the endogenous alarmin molecule high-mobility group box 1 (HMGB1) that act as a pro-inflammatory cytokine and chemoattractant during Eh infection. Eh in contact with macrophage induced a dose- and time-dependent secretion of HMGB1 in the absence of cell death. Secretion of HMGB1 was facilitated by Eh surface Gal-lectin-activated phosphoinositide 3-kinase and nuclear factor-κB signaling and up-regulation of histone acetyltransferase activity to trigger acetylated HMGB1 translocation from the nucleus. Unlike lipopolysaccharide, Eh-induced HMGB1 release was independent of caspase-1-mediated inflammasome and gasdermin D pores. In vivo, Eh inoculation in specific pathogen-free but not germ-free mice was associated with high levels of pro-inflammatory cytokines such as tumor necrosis factor-α, interleukin-1β, and keratinocyte-derived chemokine, which was suppressed with HMGB1 neutralization. This study reveals that Eh-induced active secretion of the HMGB1 plays a key role in shaping the pro-inflammatory landscape critical in innate host defense against amebiasis.

Complement C3a Not C4a Activates Osteoclasts By Regulating the PI3K/PDK1/SGK3 Pathway in Patients with Multiple Myeloma

Objective: Myeloma bone disease (MBD) is the most common complication of multiple myeloma (MM). We found that the serum levels of C3/C4 in MM patients were significantly positive correlated with the severity of bone disease in our previously study. Thus, we conduct detailed studies to explore the effect and potential mechanism of C3a/C4a on osteoclasts in patients with MM. Methods: By adding C3a/C4a to culture system of osteoclasts induced from mononuclear cells in vitro, and the expression of related gene, number and function of osteoclasts were detected. RNA-Seq analysis was used to detect the differentially expressed genes on osteoclasts between the complement group and control group, and the possible signal pathways were analyzed. Quantitative real-time PCR (qRT-PCR), Western blot and pathway inhibitors were used for further validation. R esults: In vitro, the osteoclasts area per view induced by C3a 1μg/ml (52.794±13.027 %) and 10μg/ml (51.797±12.464 %) was significantly increased than control group (0μg/ml) (33.668±8.427 %) (P<0.001; P<0.001), the mRNA relative expression of osteoclasts related genes OSCAR/TRAP/RANKL/Cathepsin K induced by C3a 1μg/ml (median 5.041; 3.726; 1.638; 4.752) and 10μg/ml (median 5.140; 3.702; 2.250; 5.172) was significantly increased than control group (0μg/ml) (median 3.137; 2.004; 0.573; 2.257) (1μg/ml P=0.001; P=0.003; P<0.001; P=0.008; 1μg/ml P<0.001; P=0.019; P<0.001; P=0.002), and the absorption area of osteoclast resorption pit per view induced by C3a 1μg/ml (51.464±11.983 %) and 10μg/ml (50.219±12.067 %) was also significantly increased than control group (0μg/ml) (33.845±8.331 %) (P<0.001; P<0.001) in NDMM patients. There was no difference among the osteoclasts area, relative expression of osteoclasts related genes and absorption area of osteoclast resorption pit between C4a (1μg/ml and 10μg/ml) group and control group (0μg/ml). RNA-Seq was performed on total RNA of osteoclasts induced by C3a in 1μg/ml group and 0μg/ml group of 4 patients with NDMM. There were 184 differentially expressed genes that were detected by RNA-Seq analysis. KEGG Pathway enrichment bubble chart shows C3a may through Phosphoinositide 3-kinase (PI3K) signaling pathways (including PI3K-Akt pathway and AKT-independent signaling pathway) promotes the proliferation of osteoclast. Upregulated differentially expressed genes in this pathway among at least 3 patients with sequencing were validated by qRT-PCR and Western Blot. It was found that the relative expression level of Phosphoinositide dependent kinase-1 (PDK1) / Serum and glucocorticoid inducible protein kinases (SGK3) genes (median 2.078; 4.428) in C3a group (1μg/ml) was significantly higher than control group (0μg/ml) (median 1.336; 1.714) (P<0.001; P=0.001). The relative grayscale levels of PDK1/ P-SGK3 protein (1.785±0.323; 2.190±0.274) in C3a group (1μg/ml) was significantly stronger than control group (0μg/ml) (0.8653±0.588; 0.176±0.152) (P=0.034; P<0.001). Under the action of C3a in patients with NDMM, osteoclasts area per view in SGK inhibitor (EMD638683) 1μM group (39.244±9.089 %) and 10μM group (39.299±9.587 %) significantly reduced than control group (0μM) (54.884±12.837 %) (P<0.001; P<0.001), the relative expression of osteoclast related genes OSCAR/RANKL/TRAP/Cathepsin K in EMD638683 1μM group (median 0.869; 1.097; 0.902; 1.328) and 10μM group (median 0.703; 1.391; 0.843; 1.418) significantly decreased than control group (0μM) (median 2.270; 3.024; 2.208; 3.237) (1μM P=0.015; P=0.002; P=0.003; P=0.015; 10μM P=0.012; P=0.006; P<0.001; P=0.017), and the absorption area per view of osteoclast resorption pit in EMD638683 1μM (35.383±7.794 %) group and 10μM group (32.886±8.993 %) significantly reduced than control group (0μM) (49.358±11.856 %) (P < 0.001; P < 0.001). Conclusions:ComplementC3a activates osteoclasts by regulating the PI3K/PDK1/SGK3 pathway in patients with MM, thus leading to the occurrence of bone diseases. SGK inhibitor has a significant inhibitory effect on osteoclasts in patients with MM. This study provide important evidences for the search for new therapeutic targets and strategies for myeloma bone disease patients. Disclosures No relevant conflicts of interest to declare.

Tyrosine Kinase Inhibitors (TKIs) Targeting Syk and BTK Signaling Differentially Affect PI3K Signalosome Organization and Platelet Function

Small molecule tyrosine kinase inhibitors (TKIs) serve increasingly important roles in the treatment of hematologic malignancies and also have shown efficacy in a range of immunological and inflammatory conditions. However, many successful TKI therapies are associated with problematic effects - particularly on platelets - as bleeding complications have been reported for many TKIs, both on and off clinical trials. Bleeding risk is especially apparent for patients treated with ibrutinib and other irreversible inhibitors of Bruton's tyrosine kinase (BTK), several of which now effectively treat multiple B cell malignancies. Intriguingly, other therapeutic TKIs targeting mechanistic partners of BTK are not associated with platelet-related complications. For instance, inhibitors against the BTK-activating kinase Syk - both with selective (i.e., entospletinib) as well as promiscuous (i.e., fostamatinib) target profiles - are not associated with clinically increased bleeding, despite some reported antiplatelet effects. To gain insight into the multifaceted effects of Syk and BTK inhibitors on platelet function, we analyzed the effects of a panel of eight different clinically relevant Syk- and BTK-directed TKIs (i.e., fostamatinib/R406, entospletinib, ibrutinib, acalabrutinib, AVL-292 and others) on essential platelet responses. We first assessed the effects of TKI treatment on Syk and BTK-mediated signaling events downstream of the platelet immunoreceptor tyrosine-based activation motif (ITAM) receptor GPVI. All Syk and BTK TKIs tested inhibited the phosphorylation of phospholipase C (PLCγ2) Y1217, protein kinase Cδ (PKCδ) Y311 and Akt T308, as well as Akt substrate phosphorylation following platelet stimulation with the GPVI receptor agonist, crosslinked collagen-related peptide (CRP-XL). Independent of TKI target profile, Syk and BTK TKIs differentially inhibited the phosphorylation of DAPP1 Y132, phosphoinositide 3-kinase (PI3K) p85α Y458, Akt S473 and PKC substrates. Syk and BTK TKIs also inhibited platelet adhesion to immobilized CRP-XL in a manner matching the effects of each TKI on ITAM-mediated signaling events. However, platelet signaling and adhesion phenotypes did not match the effects of these same TKIs on GPVI-triggered dense granule secretion, which was inhibited by all TKIs tested with the exception of R406. In contrast, all Syk and BTK inhibitors tested inhibited platelet spreading on immobilized fibrinogen. Based on observations above, we hypothesized that TKIs that irreversibly bind to BTK may disrupt critical molecular interactions around BTK within the PI3K signalosome essential to the proper orchestration of platelet activation programs. To test the effects of Syk and BTK inhibitors on the organization of PI3K signaling in activating platelets, platelets were pretreated with TKIs prior to incubation on immobilized fibrinogen and processing for immunofluorescence microscopy. We found that under control conditions, PI3K p85α regulatory subunit localized to phospholipid PI(3,4)P2-rich regions in adherent platelets associated with active PKC signaling. While Syk and PI3K inhibitors abrogated platelet spreading on fibrinogen, PI3K p85α staining remained strong around undeveloped, nascent adhesions in platelets treated with Syk and PI3K inhibitors. In contrast, PI3K p85α staining was diffuse, diminished or absent in platelets adherent to fibrinogen in the presence of all irreversible BTK inhibitors tested. Our results show that clinically effective kinase inhibitors that target Syk-BTK-PI3K signaling systems have varying effects on platelet function that may offer insights to adverse effects of therapeutic TKIs in different contexts. Moreover, our findings suggest that in addition inhibiting protein kinase activities, the discrepant effects of some TKIs may be attributed to, in part, altered protein relations around BTK, PLCγ2 and other components of the PI3K signalosome in activating platelets. Ongoing studies aim to specify protein:protein interactions affected by reversible as well as irreversible TKIs; to examine patient samples for evidence of PI3K mislocalization - especially in cases of BTK inhibitor-associated bleeding; and, to determine if PI3K signalosome disorganization has roles in other physiological, therapeutic and toxic effects of TKIs. Disclosures Shatzel: Aronora, Inc.: Consultancy.

Double PIK3CA mutations in cis increase oncogenicity and sensitivity to PI3Kα inhibitors.

Activating mutations in PIK3CA are frequent in human breast cancer, and phosphoinositide 3-kinase alpha (PI3Kα) inhibitors have been approved for therapy. To characterize determinants of sensitivity to these agents, we analyzed PIK3CA-mutant cancer genomes and observed the presence of multiple PIK3CA mutations in 12 to 15% of breast cancers and other tumor types, most of which (95%) are double mutations. Double PIK3CA mutations are in cis on the same allele and result in increased PI3K activity, enhanced downstream signaling, increased cell proliferation, and tumor growth. The biochemical mechanisms of dual mutations include increased disruption of p110α binding to the inhibitory subunit p85α, which relieves its catalytic inhibition, and increased p110α membrane lipid binding. Double PIK3CA mutations predict increased sensitivity to PI3Kα inhibitors compared with single-hotspot mutations.

Seeing double can be a good thing

Cancer Many human breast cancers harbor activating mutations in PIK3CA , the gene coding for the catalytic subunit of phosphoinositide 3-kinase (PI3K). Clinical trials are underway to evaluate the efficacy of PI3K inhibitors in cancer patients. Vasan et al. found unexpectedly that a subset of breast cancers harbor not one—but two— PIK3CA mutations, and the mutations occur on the same allele (see the Perspective by Toker). In model systems, the double mutations hyperactivate PI3K signaling and enhance tumor growth. Preliminary analysis of clinical trial data suggests that breast cancers with double mutations are more responsive to PI3K inhibitors than those with a single mutation. PIK3CA mutational status could help identify the breast cancer patients most likely to benefit from these drugs. Science , this issue p. [714][1]; see also p. [685][2] [1]: /lookup/doi/10.1126/science.aaw9032 [2]: /lookup/doi/10.1126/science.aaz4016

EGR1 upregulation following Venezuelan equine encephalitis virus infection is regulated by ERK and PERK pathways contributing to cell death

Venezuelan equine encephalitis virus (VEEV) is a neurotropic virus that causes significant disease in both humans and equines. Here we characterized the impact of VEEV on signaling pathways regulating cell death in human primary astrocytes. VEEV productively infected primary astrocytes and caused an upregulation of early growth response 1 (EGR1) gene expression at 9 and 18 h post infection. EGR1 induction was dependent on extracellular signal-regulated kinase1/2 (ERK1/2) and protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK), but not on p38 mitogen activated protein kinase (MAPK) or phosphoinositide 3-kinase (PI3K) signaling. Knockdown of EGR1 significantly reduced VEEV-induced apoptosis and impacted viral replication. Knockdown of ERK1/2 or PERK significantly reduced EGR1 gene expression, dramatically reduced viral replication, and increased cell survival as well as rescued cells from VEEV-induced apoptosis. These data indicate that EGR1 activation and subsequent cell death are regulated through ERK and PERK pathways in VEEV infected primary astrocytes.

A PDGFRβ-PI3K signaling axis mediates periosteal cell activation during fracture healing.

Insufficient and delayed fracture healing remain significant public health problems with limited therapeutic options. Phosphoinositide 3-kinase (PI3K) signaling, a major pathway involved in regulation of fracture healing, promotes proliferation, migration, and differentiation of osteoprogenitors. We have recently reported that knock-in mice with a global increase in PI3K signaling (gCblYF) show enhanced femoral fracture healing characterized by an extraordinary periosteal response to injury. Interestingly, of all growth factor receptors involved in fracture healing, PI3K directly binds only to PDGFR. Given these findings, we hypothesized a PDGFR-PI3K interaction is necessary for mediating robust periosteal cell activation following fracture. In this study, we isolated primary periosteal cells from gCblYF mice to analyze cross-talk between the PDGFRβ and PI3K signaling pathways. We found PDGFRβ signaling contributes to robust Akt phosphorylation in periosteal cells in comparison with other growth factor signaling pathways. Additionally, we performed femoral fractures on gCblYF mice with a conditional removal of PDGFRβ in mesenchymal progenitors using inducible alpha smooth muscle actin (αSMA) CreERT2 mice. Our studies showed that depletion of PDGFRβ signaling within these progenitors in the early phase of fracture healing significantly abrogates PI3K-mediated periosteal activation and proliferation three days after fracture. Combined, these results suggest that PDGFRβ signaling through PI3K is necessary for robust periosteal activation in the earliest phases of fracture healing.

Endometrial Cancer General Perspectives, Epidemiology

This paper focuses on the epidemiologic factors that are effective on the pathology of the endometrial malignancy. Based on previous reviews and recent articles on endometrial cancer, we sought to define risk factors and related diseases to endometrial malignancies. Previous studies have shown that phosphoinositide 3-kinase (PI3K) activity is stimulated by diverse oncogenes and growth factor receptors, and elevated PI3K signaling is considered a hallmark of cancer. A major antagonist of PI3K activity is phosphatase and tensin homolog (PTEN), a tumor suppressor which is often mutated or lost in type I endometrial cancer cells. Endometrial cancer is still a problem in developed countries since adiposity and sedentary way of life. However, we have not found a feasible way to screen endometrial malignancies. In the future, with the advancing of genetic studies, screening could be applicable.

Class I phosphoinositide 3-kinase (PI3K) regulatory subunits and their roles in signaling and disease.

The Class I phosphoinositide 3-kinases (PI3Ks) are a group of heterodimeric lipid kinases that regulate crucial cellular processes including proliferation, survival, growth, and metabolism. The diversity in functions controlled by the various catalytic isoforms (p110α, p110β, p110δ, and p110γ) depends on their abilities to be activated by distinct stimuli such as receptor tyrosine kinases (RTKs), G-protein coupled receptors (GPCRs), and the Ras family of small G-proteins. A major factor determining the ability of each p110 enzyme to be activated is the presence of regulatory binding partners. Given the overwhelming evidence for the involvement of PI3Ks in diseases such as cancer, inflammation, immunodeficiency and diabetes, an understanding of how these regulatory proteins influence PI3K function is essential. This article highlights research deciphering the role of regulatory subunits in PI3K signaling and their involvement in human disease.

The Role of PTEN in Innate and Adaptive Immunity.

The lipid and protein phosphatase and tensin homolog (PTEN) controls the differentiation and activation of multiple immune cells. PTEN acts downstream from T- and B-cell receptors, costimulatory molecules, cytokine receptors, integrins, and also growth factor receptors. Loss of PTEN activity in human and mice is associated with cellular and humoral immune dysfunction, lymphoid hyperplasia, and autoimmunity. Although most patients with PTEN hamartoma tumor syndrome (PHTS) have no immunological symptoms, a subclinical immune dysfunction is present in many, and clinical immunodeficiency in few. Comparison of the immune phenotype caused by PTEN haploinsufficiency in PHTS, phosphoinositide 3-kinase (PI3K) gain-of-function in activated PI3K syndrome, and mice with conditional biallelic Pten deletion suggests a threshold model in which coordinated activity of several phosphatases control the PI3K signaling in a cell-type-specific manner. Emerging evidence highlights the role of PTEN in polygenic autoimmune disorders, infection, and the immunological response to cancer. Targeting the PI3K axis is an emerging therapeutic avenue.

Electroacupuncture attenuates chronic fibromyalgia pain through the phosphorylated phosphoinositide 3-kinase signaling pathway in the mouse brain.

Objective(s):Fibromyalgia (FM) is a central nervous system disorder characterized by widespread mechanical hyperalgesia due to unknown mechanisms. Several inflammatory mediators, such as interleukin-1 (IL-1), IL-6, IL-8, and tumor necrosis factor, are increased in the serum of FM patients. Although medications including pregabalin, duloxetine, and milnacipran are used to treat FM, the results are unsatisfying. In the present study we assessed whether electroacupuncture (EA) can reduce chronic FM pain and then proposed an underlying mechanism for this effect. Materials and Methods:Chronic FM pain was induced in mice by dual acid saline injection lasting up to 4 weeks. Results:Chronic FM pain was treated by EA manipulation, but not in the sham operated group. Phosphorylated phosphatidylinositol 3-kinase (pPI3K), protein kinase B, mechanistic target of rapamycin, and nuclear factor kappa-light-chain-enhancer of activated B cells were unaltered in the mouse dorsal root ganglion (DRG) and spinal cord (SC) after inducing FM and administering EA treatment. The pPI3K-associated nociceptive signaling pathway was increased in the thalamus of FM mice, but reversed by EA. Similar results were observed in the mouse somatosensory cortex. Conclusion:These data suggest that EA has a significant effect on a signaling pathway in brain areas of FM mice. These findings suggest the value of EA for clinical practice.

Effective Treatment of Metastatic Melanoma by Combining MAPK and PI3K Signaling Pathway Inhibitors.

Malignant melanoma is the most aggressive type of skin cancer and is closely associated with the development of brain metastases. Despite aggressive treatment, the prognosis has traditionally been poor, necessitating improved therapies. In melanoma, the mitogen activated protein kinase and the phosphoinositide 3-kinase signaling pathways are commonly altered, and therapeutically inhibiting one of the pathways often upregulates the other, leading to resistance. Thus, combined treatment targeting both pathways is a promising strategy to overcome this. Here, we studied the in vitro and in vivo effects of the PI3K inhibitor buparlisib and the MEK1/2 inhibitor trametinib, used either as targeted monotherapies or in combination, on patient-derived melanoma brain metastasis cell lines. Scratch wound and trans-well assays were carried out to assess the migratory capacity of the cells upon drug treatment, whereas flow cytometry, apoptosis array and Western blots were used to study apoptosis. Finally, an in vivo treatment experiment was carried out on NOD/SCID mice. We show that combined therapy was more effective than monotherapy. Combined treatment also more effectively increased apoptosis, and inhibited tumor growth in vivo. This suggests a clinical potential of combined treatment to overcome ceased treatment activity which is often seen after monotherapies, and strongly encourages the evaluation of the treatment strategy on melanoma patients with brain metastases.

PI3K Signaling in Chronic Obstructive Pulmonary Disease: Mechanisms, Targets, and Therapy.

Chronic Obstructive Pulmonary Disease (COPD) is a progressive respiratory disorder characterized by irreversible chronic inflammation and airflow obstruction. It affects more than 64 million patients worldwide and it is predicted to become the third cause of death in the industrialized world by 2030. Currently available therapies are not able to block disease progression and to reduce mortality, underlying the need for a better understanding of COPD pathophysiological mechanisms to identify new molecular therapeutic targets. Recent studies demonstrated that phosphoinositide 3-kinase (PI3K) signaling is prominently activated in COPD and correlates with an increased susceptibility of patients to lung infections. PI3Ks have thus emerged as promising alternative drug targets for COPD and a wide array of pan-isoform and isoform-selective inhibitors have been tested in preclinical models and are currently being evaluated in clinical studies. Here, we summarize the recent knowledge on the involvement of PI3K enzymes in the pathophysiology of COPD, and we discuss the most recent results arising from the preclinical as well as the clinical testing of PI3K inhibitors as novel therapeutics for COPD.

For Better or Worse: The Potential for Dose Limiting the On-Target Toxicity of PI 3-Kinase Inhibitors.

The hyper-activation of the phosphoinositide (PI) 3-kinase signaling pathway is a hallmark of many cancers and overgrowth syndromes, and as a result, there has been intense interest in the development of drugs that target the various isoforms of PI 3-kinase. Given the key role PI 3-kinases play in many normal cell functions, there is significant potential for the disruption of essential cellular functions by PI 3-kinase inhibitors in normal tissues; so-called on-target drug toxicity. It is, therefore, no surprise that progress within the clinical development of PI 3-kinase inhibitors as single-agent anti-cancer therapies has been slowed by the difficulty of identifying a therapeutic window. The aim of this review is to place the cellular, tissue and whole-body effects of PI 3-kinase inhibition in the context of understanding the potential for dose limiting on-target toxicities and to introduce possible strategies to overcome these.

PI3Kβ is selectively required for growth factor-stimulated macropinocytosis.

Macropinocytosis is an actin-dependent but clathrin-independent endocytic process by which cells nonselectively take up large aliquots of extracellular material. Macropinocytosis is used for immune surveillance by dendritic cells, as a route of infection by viruses and protozoa, and as a nutrient uptake pathway in tumor cells. In this study, we explore the role of class I phosphoinositide 3-kinases (PI3Ks) during ligand-stimulated macropinocytosis. We find that macropinocytosis in response to receptor tyrosine kinase activation is strikingly dependent on a single class I PI3K isoform, namely PI3Kβ (containing the p110β catalytic subunit encoded by PIK3CB). Loss of PI3Kβ expression or activity blocks macropinocytosis at early steps, before the formation of circular dorsal ruffles, but also plays a role in later steps, downstream from Rac1 activation. PI3Kβ is also required for the elevated levels of constitutive macropinocytosis found in tumor cells that are defective for the PTEN tumor suppressor. Our data shed new light on PI3K signaling during macropinocytosis, and suggest new therapeutic uses for pharmacological inhibitors of PI3Kβ.