Cellular function of phosphoinositide 3-kinases: implications for development, homeostasis, and cancer

Inhibition of AKT signalling by benzoxazine derivative LTUR6 through the modulation of downstream kinases

Many compounds structurally similar to chromones have been developed to enhance the sensitizing effect of cancer cells to chemotherapeutic agents. Most of these compounds have been shown to promote this sensitization by targeting the repair pathways. One such compound is LTUR6, which enhances the sensitization of doxorubicin to colon cancer cells HT29, by inhibiting the phosphorylation of the double stranded break (DSB) repair enzyme AKT. The downstream regulatory targets of AKT that enhance doxorubicin mediated cytotoxicity in the presence of LTUR6 remains elusive. In this study, we performed comparative analyses of 43 kinase phosphorylation sites using the human phospho-kinase array proteome profiler. Results revealed altered expression levels of multiple proteins that regulated apoptotic signalling pathways. Increased activation of mTOR, RSK1/2/3, p38α and PRAS40 after combination treatment with LTUR6 and doxorubicin over doxorubicin alone was observed. This study provides a deeper insight into the key proteins involved and presents a novel molecular pathway.

Tau-TCHF Inhibits Spleenic Apoptosis via PI3K-Akt Signaling Pathway in Chickens

Taurine plays an important role in improving immunity, regulating cell proliferation and differentiation, apoptosis and so on. Traditional Chinese herb formula (TCHF) is a wealth of medicine materials for diseases control. There are many studies on Chinese herb formula in inducing cell apoptosis, differentiation and improving animal immunity. The factors in phosphatidylinositol 3-kinase/Protein Kinase (PI3K-Akt) signaling pathway are central regulators of normal cells, which integrates extra-cellular signals into cells and activates affects cell activities including cell proliferation, differentiation and apoptosis. We find the key factors (PIK3CA, PDPK1, AKT1, MDM2, ITGA2B, ITGB1, FAK and p53) in PI3K-Akt signaling pathway by RNA-Seq analysis in our previous research. The overall goal of this study to investigate the influence of taurine TCHF (Tau-TCHF) on cell proliferation, differentiation and apoptosis by estimating the factors above. The layers were fed with normal diet plus 1% of Tau-TCHF and the control group with normal diet to 42 days old. The spleen tissue samples from individual layers were used to analyze the influence of Tau-TCHF on the factors PIK3CA, PDPK1, AKT1, MDM2, ITGA2B, ITGB1, FAK and p53 in PI3K-Akt signaling pathway. The levels of transcription and protein expression of various factors were assessed by quantitative PCR (qPCR) and Western Blot. The results showed that the transcription levels of itgb1, fak, pik3ca, akt1 and mdm2 on 42-day-old chicken spleen tissues were increased significantly in Tau-TCHF group comparing with control group (P < 0.01); the transcription levels of itga2b, pdpk1 and p53 were no significant difference (P > 0.05). The protein levels of PDPK1 and AKT (Ser437) were increased significantly (P < 0.05), but ITGA2B, ITGB1, FAK, PIK3CA, AKT1, MDM2 and p53 had no significant difference (P > 0.05). The results suggest that Tau-TCHF may influence proliferation and differentiation of chickens spleen via regulating PI3K-Akt signaling pathway. And Tau-TCHF may be provided as feed additives in improving the immunity of animals. AKT (Ser473) and PDPK1 may be considered as further targets to study mechanism of Tau-TCHF on anti-apoptosis via PI3K-Akt signaling pathway.

The core planar cell polarity gene, Vangl2, maintains apical-basal organisation of the corneal epithelium

The role of the core planar cell polarity (PCP) pathway protein, Vangl2, was investigated in the corneal epithelium of the mammalian eye, a paradigm anatomical model of planar cell migration. The gene was conditionally knocked out in vivo and knocked down by siRNA, followed by immunohistochemical, behavioural and morphological analysis of corneal epithelial cells. The primary defects observed in vivo were of apical-basal organisation of the corneal epithelium, with abnormal stratification throughout life, mislocalisation of the cell membrane protein, Scribble, to the basal side of cells, and partial loss of the epithelial basement membrane. Planar defects in migration after wounding and in the presence of an applied electric field were noted. However, knockdown of Vangl2 also retarded cell migration in individual cells that had no contact with their neighbours, which precluded a classic PCP mechanism. It is concluded that some of the planar polarity phenotypes in PCP mutants may arise from disruption of apical-basal polarity.

XB130 Knockdown Inhibits the Proliferation, Invasiveness, and Metastasis of Hepatocellular Carcinoma Cells and Sensitizes them to TRAIL-Induced Apoptosis

Background

XB130 is a recently discovered adaptor protein that is highly expressed in many malignant tumors, but few studies have investigated its role in hepatocellular carcinoma (HCC). Therefore, this study explored the relationship between this protein and liver cancer and investigated its molecular mechanism of action.

Methods

The expression of XB130 between HCC tissues and adjacent nontumor tissues was compared by real-time polymerase chain reaction, immunochemistry, and Western blotting. XB130 silencing was performed using small hairpin RNA. The effect of silencing XB130 was examined using Cell Counting Kit-8, colony assay, wound healing assay, and cell cycle analysis.

Results

We found that XB130 was highly expressed in HCC tissues (cancer tissues vs. adjacent tissues: 0.23 ± 0.02 vs. 0.17 ± 0.02, P < 0.05) and liver cancer cell lines, particularly MHCC97H and HepG2 (MHCC97H and HepG2 vs. normal liver cell line LO-2: 2.35 ± 0.26 and 2.04 ± 0.04 vs. 1.00 ± 0.04, respectively, all P < 0.05). The Cell Counting Kit-8 assay, colony formation assay, and xenograft model in nude mice showed that silencing XB130 inhibited cell proliferative ability both in vivo and in vitro, with flow cytometry demonstrating that the cells were arrested in the G0/G1 phase in HepG2 (HepG2 XB130-silenced group [shA] vs. HepG2 scramble group [NA]: 74.32 ± 5.86% vs. 60.21 ± 3.07%, P < 0.05) and that the number of G2/M phase cells was decreased (HepG2 shA vs. HepG2 NA: 8.06 ± 2.41% vs. 18.36 ± 4.42%, P < 0.05). Furthermore, the cell invasion and migration abilities were impaired, and the levels of the epithelial-mesenchymal transition-related indicators vimentin and N-cadherin were decreased, although the level of E-cadherin was increased after silencing XB130. Western blotting showed that the levels of phosphorylated phosphoinositide 3-kinase (PI3K) and phospho-protein kinase B (p-Akt) also increased, although the level of phosphorylated phosphatase and tensin homolog increased, indicating that XB130 activated the PI3K/Akt pathway. Furthermore, we found that a reduction in XB130 increased liver cancer cell sensitivity to tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis.

Conclusions

Our findings suggest that XB130 might be used as a predictor of liver cancer as well as one of the targets for its treatment.

PI3K/Akt signaling transduction pathway, erythropoiesis and glycolysis in hypoxia (Review)

The purpose of this review is to summarize the research progress of PI3K/Akt signaling pathway in erythropoiesis and glycolysis. Phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) is activated by numerous genes and leads to protein kinase B (Akt) binding to the cell membrane, with the help of phosphoinositide-dependent kinase, in the PI3K/Akt signal transduction pathway. Threonine and serine phosphorylation contribute to Akt translocation from the cytoplasm to the nucleus and further mediates enzymatic biological effects, including those involved in cell proliferation, apoptosis inhibition, cell migration, vesicle transport and cell cancerous transformation. As a key downstream protein of the PI3K/Akt signaling pathway, hypoxia-inducible factor (HIF)-1 is closely associated with the concentration of oxygen in the environment. Maintaining stable levels of HIF-1 protein is critical under normoxic conditions; however, HIF-1 levels quickly increase under hypoxic conditions. HIF-1α is involved in the acute hypoxic response associated with erythropoietin, whereas HIF-2α is associated with the response to chronic hypoxia. Furthermore, PI3K/Akt can reduce the synthesis of glycogen and increase glycolysis. Inhibition of glycogen synthase kinase 3β activity by phosphorylation of its N-terminal serine increases accumulation of cyclin D1, which promotes the cell cycle and improves cell proliferation through the PI3K/Akt signaling pathway. The PI3K/Akt signaling pathway is closely associated with a variety of enzymatic biological effects and glucose metabolism.

Bmp4 inhibits goose granulosa cell apoptosis via PI3K/AKT/Caspase-9 signaling pathway

Bone morphogenetic protein 4 (BMP4) has an important role in regulating cellular proliferation, differentiation and apoptosis. It, however, is still unclear as to the mechanisms by which BMP4 regulates the apoptosis of granulosa cells (GCs) in geese. In the present study, there was cloning of the full-length coding sequence of goose BMP4 gene, which consisted of 1212 nucleotides encoding 403 amino acids. Its deduced amino acid sequence comprised one signal peptide, one TGFβ pro-peptide and one mature peptide domain. Results from conducting the quantitative real-time PCR (qPCR) indicated the relative abundances of BMP4 mRNA in geese GCs increased gradually from the relative abundances in pre-hierarchical follicles that were 4 to 6 mm in diameter to that in the fifth largest (F5) follicle and then relative abundances of BMP4 mRNA decreased with further development as the largest (F1) follicle. Results from use of the TUNEL assay indicated that overexpression of the goose BMP4 gene suppressed GC apoptosis and this was confirmed when relative abundances of the CAD, Caspase-9 and Caspase-3 proteins were determined using western blotting. In addition, overexpression of the BMP4 gene induced phosphorylation of AKT, which was inhibited with use of the PI3K inhibitor, LY294002. Co-transfection of BMP4 and LY294002 resulted in increased relative abundances of Caspase-9 and CAD proteins but had no effect on that of Caspase-3. Taken together, these results suggested that expression of the BMP4 gene resulted in a reduction in Caspase-9 protein leading to inhibition of GC apoptosis via the PI3K/AKT signaling pathway in geese.

Therapeutic Potency of PI3K Pharmacological Inhibitors of Gastrointestinal Cancer

Therapeutic targeting of phosphatidyl-inositol 3-kinase (PI3K) is considered as a possible strategy in several types of cancer, including gastrointestinal ones. In vitro and in vivo studies indicated the significance of proapoptotic and antiproliferative inhibition of PI3K. Although there are many phase 1 and 2 clinical trials on PI3K inhibitors in patients with gastrointestinal cancer, the molecular mechanism of PI3K targeting PI3K/ mTOR pathway is not clear. Panclass I, isoformselective, and dual PI3K/mTOR inhibitors are under investigation. This review aimed to indicate PI3K-dependent targeting mechanisms in gastrointestinal cancer and the evaluation of related clinical data.

High-throughput screening campaigns against a PI3Kα isoform bearing the H1047R mutation identified potential inhibitors with novel scaffolds

The phosphatidylinositol 3-kinase (PI3K) pathway is involved in many cellular functions including cell growth, metabolism, and transformation. Hyperactivation of this pathway contributes to tumorigenesis, therefore, PI3K is a major target for anticancer drug discovery. Since the PI3Kα isoform is implicated mostly in cancer, we conducted a high-throughput screening (HTS) campaign using a 3-step PI3K homogenous time-resolved fluorescence assay against this isoform bearing the H1047R mutation. A total of 288,000 synthetic and natural product-derived compounds were screened and of which, we identified 124 initial hits that were further selected by considering the predicted binding mode, relationship to known pan-assay interference compounds and previous descriptions as a lipid kinase inhibitor. A total of 24 compounds were then tested for concentration-dependent responses. These hit compounds provide novel scaffolds that can potentially be optimized to create novel PI3K inhibitors.

Targeting phosphoinositide-3-kinase pathway in biliary tract cancers: A remedial route?

Biliary tract cancers (BTC) are aggressive tumours with a low survival rate. At the advent of the genomic era, various genetic mutations in cell signalling pathways have been incriminated in carcinogenesis. Genomic analysis studies have connected main components of the phosphoinositide-3-kinase (PI3K) signalling pathway to BTC. PI3K pathway playing a central role in cell signalling and being deregulated in various tumours has been studied as a target for chemotherapy. Novel compounds have also been identified in preclinical trials that specifically target the PI3K pathway in BTCs, but these studies have not accelerated to clinical use. These novel compounds can be examined in upcoming studies to validate them as potential therapeutic agents, as further research is required to combat the growing need for adjuvant chemotherapy to successfully battle this tumour type. Furthermore, these molecules could also be used along with gemcitabine, cisplatin and 5-fluorouracil to improve sensitivity of the tumour tissue to chemotherapy. This review focuses on the basics of PI3K signalling, genetic alterations of this pathway in BTCs and current advancement in targeting this pathway in BTCs. It emphasizes the need for gene-based drug screening in BTC. It may reveal various novel targets and drugs for amelioration of survival in patients with BTC and serve as a stepping stone for further research.

Serum and glucocorticoid inducible protein kinases (SGKs): a potential target for cancer intervention

The serum and glucocorticoid inducible protein kinase (SGK) family members share similar structure, substrate specificity and function with AKT and signal downstream of the phosphatidylinositol 3-kinase (PI3K) signalling pathway. They regulate a range of fundamental cellular processes such as cell proliferation and survival, thereby playing an important role in cancer development. This perspective intends to give an overview on the involvement of SGKs (particularly SGK3) in cancer progression, and compares the actions of SGK3 and AKT in cell cycle regulation, oncogenic signalling, and the potential as a therapeutic target for cancer.

The next generation of PI3K-Akt-mTOR pathway inhibitors in breast cancer cohorts

The PI3K/Akt/mTOR pathway plays a role in various oncogenic processes in breast cancer and key pathway aberrations have been identified which drive the different molecular subtypes. Early drugs developed targeting this pathway produced some clinical success but were hampered by pharmacokinetics, tolerability and efficacy problems. This created a need for new PI3K pathway-inhibiting drugs, which would produce more robust results allowing incorporation into treatment regimens for breast cancer patients. In this review, the most promising candidates from the new generation of PI3K-pathway inhibitors is explored, presenting evidence from preclinical and early clinical research, as well as ongoing trials utilising these drugs in breast cancer cohorts. The problems hindering the development of drugs targeting the PI3K pathway are examined, which have created problems for their use as monotherapies. PI3K pathway inhibitor combinations therefore remains a dynamic research area, and their role in combination with immunotherapies and epigenetic therapies is also inspected.

Mutational Profile of Metastatic Breast Cancer Tissue in Patients Treated with Exemestane Plus Everolimus

Background

Everolimus has been shown to overcome endocrine resistance in hormone receptor positive advanced breast cancer patients. Predictive biomarkers of everolimus efficacy have been investigated in primary breast cancer tissue without finding univocal results. The goal of this study was to investigate the mutational burden in the metastatic site of endocrine-resistant tumors treated with everolimus plus exemestane.

Patients and Methods

Mass Array Sequenom platform was used to analyse genetic status of 18 cancer-related genes in 25 archival tumor specimens from metastatic lesions and available primary matched breast cancer tissue of patients treated with everolimus and exemestane for advanced disease. An exploratory analysis of everolimus efficacy in terms of progression free survival benefit and single gene mutation was carried out.

Results

The overall detection rate of mutation was 30% and 38% from metastatic and primary breast cancer samples, respectively. AKT1^E17K was the most frequent mutated gene. No primary breast cancer and matched relapse maintained the same mutation profile. Considering molecular pathways, the most of the genes belong to PI3K pathway (AKT1^E17K, PI3KCA^E545K, and KIT^G565R,S709F). In patients with detected mutations in breast and/or recurrence tissue the median PFS was 5,6 months while in the subgroup of patients with no mutations the median PFS was 7,5 months.

Conclusions

The mutational status of breast cancer recurrence allows the identification of some genes potentially correlating tumor response/resistance to everolimus. The most frequently mutated genes were involved in the PI3K/AKT/mTOR pathway highlighting that the deregulation of this pathway in the relapse plays a crucial role in the mechanisms of everolimus resistance/sensitivity. Owing to the small sample size and the retrospective nature of the study, these correlations need to be validated in a large prospective study.

Suppression of Notch1 and AKT mediated epithelial to mesenchymal transition by Verrucarin J in metastatic colon cancer

Epithelial to mesenchymal transition (EMT) in colorectal cancer (CRC) has been attributed to activation of AKT and Notch1 signaling pathways. As EMT corresponds to increased aggressiveness of CRC, approaches that prevent metastasis by targeting AKT/Notch1 pathways are at the forefront of current research paradigms. This study examined the anti-metastatic potential of Verrucarin J (VJ), a small molecule, in CRC cells overexpressing AKT and Notch1. VJ significantly inhibited AKT/HCT 116 cell growth by acting on the AKT/NFκB/Bcl-2 signaling axis and initiated apoptotic signaling as was evident from increased expression of pro-apoptotic markers such as cleaved PARP, cleaved caspase 3, and cleaved caspase 9. Also, VJ inhibited the cell growth in AKT/Notch1-overexpressing CRC cells and abrogated EMT. The down-regulation of AKT and Notch1 signaling was apparent in immunoblot analysis and corresponded with down-regulation of mesenchymal markers including Snail, and β-catenin. Intraperitoneal administration of VJ in control (pCMV/HCT 116) and AKT/HCT 116 mice significantly suppressed AKT-induced tumor growth in a xenograft model. In addition, down-regulation of prosurvival markers as well as AKT and Notch1 was observed in the immunohistochemical analysis of the xenografted tumors. In conclusion, our study substantiates the role of AKT and Notch1 in cell proliferation, angiogenesis, and EMT of CRC cells and demonstrates that VJ may be a viable therapeutic option to counter AKT-induced cell proliferation and tumor outgrowth in CRC.

Discovery of an Orally Bioavailable Dual PI3K/mTOR Inhibitor Based on Sulfonyl-Substituted Morpholinopyrimidines

The discovery and optimization of a series of 2-morpholino-pyrimidine derivatives containing various sulfonyl side chains at the C₄ position led to the identification of compound 26 as a potent dual PI3K/mTOR inhibitor. It exhibited high inhibitory activity against PI3Kα/β/γ/δ (IC₅₀ = 20/376/204/46 nM) and mTOR (IC₅₀ = 189 nM), potent functional suppression of AKT phosphorylation (IC₅₀ = 196 nM), and excellent antiproliferative effects on a panel of cancer cells. Enzymic data and modeling simulation indicate that a cyclopropyl ring on the C₄ sulfone chain and a fluorine on the C₆ aminopyridyl moiety are responsible for its maintained PI3K activity and enhanced mTOR potency, respectively. Furthermore, compound 26 exhibited higher efficiency in the HT-29 colorectal carcinoma xenograft model at the daily dose of 3.75 and 7.5 mg/kg relative to BKM120 at the dose of 15 and 30 mg/kg.

Understanding the biology of HER3 receptor as a therapeutic target in human cancer

HER3 belongs to the human epidermal growth factor receptor (HER) family which also includes HER1/EGFR/erbB1, HER2/erbB2, and HER4/erbB4. As a unique member of the HER family, HER3 lacks or has little intrinsic tyrosine kinase activity. It frequently co-expresses and forms heterodimers with other receptor tyrosine kinases (RTKs) in cancer cells to activate oncogenic signaling, especially the PI-3K/Akt pathway and Src kinase. Elevated expression of HER3 has been observed in a wide variety of human cancers and associates with a worse survival in cancer patients with solid tumors. Studies on the underlying mechanism implicate HER3 expression as a major cause of treatment failure in cancer therapy. Activation of HER3 signaling has also been shown to promote cancer metastasis. These data strongly support the notion that therapeutic inactivation of HER3 and/or its downstream signaling is required to overcome treatment resistance and improve the outcomes of cancer patients.

PI3K: A Crucial Piece in the RAS Signaling Puzzle

RAS proteins are key signaling switches essential for control of proliferation, differentiation, and survival of eukaryotic cells. RAS proteins are mutated in 30% of human cancers. In addition, mutations in upstream or downstream signaling components also contribute to oncogenic activation of the pathway. RAS proteins exert their functions through activation of several signaling pathways and dissecting the contributions of these effectors in normal cells and in cancer is an ongoing challenge. In this review, we summarize our current knowledge about how RAS regulates type I phosphatidylinositol 3-kinase (PI3K), one of the main RAS effectors. RAS signaling through PI3K is necessary for normal lymphatic vasculature development and for RAS-induced transformation in vitro and in vivo, especially in lung cancer, where it is essential for tumor initiation and necessary for tumor maintenance.

Aspirin acts in esophageal cancer: a brief review

Improved survival in esophageal cancer patients with regular aspirin use have been reported. However, with conflicting experimental results existed, an explicit definition on the role of aspirin as an adjuvant chemotherapy of esophageal cancer remains unestablished. We have summarized the current epidemiologic trials evidence over antitumor effect of aspirin in esophageal cancer in the past decades, and most of the clinical data supports that long-term regular aspirin use could reduce the mortality and improve the survival in patients with esophageal cancer. Although most of the clinical trials of aspirin on esophageal cancer are designed focusing on the prediagnosed chemo-preventive role, other than the post-diagnosed therapeutic role, it has been suggested by some studies that aspirin use as an adjuvant treatment after the standard surgery in esophageal cancer may benefit more. In the meanwhile, post diagnosed aspirin use may lead to lower risk of hemorrhage and other side effects of NSAIDs. Potential involved molecular pathways in the antitumor activities of aspirin are under studied worldwide for years and the possible mechanisms so far are reviewed in this article as cyclooxygenase (COX)-dependent pathways and COX-independent pathways, involving anti-inflammatory activity, apoptosis, platelet deactivation, PIK3CA mutation specificity and heparanase-related microenvironment changes of tumor cells. NOSH-aspirin has been developed as a succedaneum of aspirin with a wider application ranges by reducing the risk of hemorrhage in aspirin users. Further clinical and basic studies are suggested focusing on whether regular aspirin use as an adjuvant treatment prolongs survival and prevents recurrence in patients with esophageal cancer.

Phosphoinositides and their functions in apicomplexan parasites

Phosphoinositides are the phosphorylated derivatives of the structural membrane phospholipid phosphatidylinositol. Single or combined phosphorylation at the 3, 4 and 5 positions of the inositol ring gives rise to the seven different species of phosphoinositides. All are quantitatively minor components of cellular membranes but have been shown to have important functions in multiple cellular processes. Here we describe our current knowledge of phosphoinositide metabolism and functions in apicomplexan parasites, mainly focusing on Toxoplasma gondii and Plasmodium spp. Even though our understanding is still rudimentary, phosphoinositides have already shown their importance in parasite biology and revealed some very particular and parasite-specific functions. Not surprisingly, there is a strong potential for phosphoinositide synthesis to be exploited for future anti-parasitic drug development.

The prognostic value of PI3K mutational status in breast cancer: A meta-analysis

Breast cancer (BC) is the second most common cause of cancer-related deaths in women worldwide. The availability of reliable biomarkers of response/resistance to cancer treatments would benefit patients and clinicians allowing for a better selection of BC patients most likely to respond to a specific treatment. Phosphatidylinositol 3-kinase (PI3K) enzymes are involved in numerous cellular- functions and processes. The gene encoding for PI3K catalytic subunit p110α is mutated in 20-40% of BC. We performed a meta-analysis of the current literature on randomized clinical trials, investigating the role of PIK3CA mutational status as prognostic factor, and predictor of response to anti-cancer treatments. Overall 1929 cases were included. The pooled analysis confirmed that the presence of a PIK3CA mutation represents an independent negative prognostic factor (HR = 1.67, 95%CI: 1.15-2.43; P = 0.007) in BC, as previously reported. As PI3K signaling is also a result of other pathways' hyperactivation, further investigation of potential biomarkers able to predict likelihood of response to anti-PI3K/mTOR, anti-HER2, and other TKRs is warranted in future randomized clinical trials.

High throughput chemical library screening identifies a novel p110-δ inhibitor that potentiates the anti-myeloma effect of bortezomib

Multiple myeloma (MM) remains an incurable plasma cell malignancy and drug resistance persists as the major cause of treatment failure leading to fatal outcomes. The phosphatidyl-inositol-3-kinase (PI3K) pathway is constitutively hyperactivated in MM to promote disease progression and drug resistance. While inhibiting PI3K induces apoptosis in MM and is predicted to increase tumor susceptibility to anticancer therapy, early-generation pan-PI3K inhibitors display poor clinical efficacy as well as intolerable side effects. Here, we found that PI3K activity is significantly upregulated in MM cell lines and patient tumor cells resistant to bortezomib and that the majority of PI3K activity in MM cells is dependent upon the p110-δ isoform. Genetic or pharmacologic inhibition of p110-δ substantially reduced myeloma viability and enhanced cellular sensitivity to bortezomib. Chemical library screens then identified a novel compound, DT97, that potently inhibited p110-δ kinase activity and induced apoptosis in MM cells. DT97 was evaluated in the NCI-60 panel of human cancer cell types and anticancer activity was greatest against MM, leukemia and lymphoma cells. Co-treatment with DT97 and bortezomib synergistically induced apoptosis in MM patient cells and overcame bortezomib-resistance. Although bone marrow stromal cells (BMSCs) promote MM growth, the pro-survival effects of BMSCs were significantly reduced by DT97 treatment. Co-treatment with bortezomib and DT97 reduced the growth of myeloma xenotransplants in murine models and prolonged host survival. Taken together, the results provide the basis for further clinical evaluation of p110-δ inhibitors, as monotherapy or in synergistic combinations, for the benefit of MM patients.

Mitomycin C treatment induces resistance and enhanced migration via phosphorylated Akt in aggressive lung cancer cells

Since 1984, mitomycin C (MMC) has been applied in the treatment of non-small-cell lung cancer (NSCLC). MMC-based chemotherapeutic regimens are still under consideration owing to the efficacy and low cost as compared with other second-line regimens in patients with advanced NSCLC. Hence, it is important to investigate whether MMC induces potential negative effects in NSCLC. Here, we found that the malignant lung cancer cells, CL1-2 and CL1-5, were more resistant to MMC than were the parental CL1-0 cells and pre-malignant CL1-1 cells. CL1-2 and CL1-5 cells consistently showed lower sub-G1 fractions post MMC treatment. DNA repair-related proteins were not induced more in CL1-5 than in CL1-0 cells, but the levels of endogenous and MMC-induced phosphorylated Akt (p-Akt) were higher in CL1-5 cells. Administering a p-Akt inhibitor reduced the MMC resistance, demonstrating that p-Akt is important in the MMC resistance of CL1-5 cells. Furthermore, we revealed that cell migration was enhanced by MMC but lowered by a p-Akt inhibitor in CL1-5 cells. This study suggests that in CL1-5 cells, the activity of p-Akt, rather than DNA repair mechanisms, may underlie the resistance to MMC and enhance the cells' migration abilities after MMC treatment.

Targeting Cyclin D-CDK4/6 Sensitizes Immune-Refractory Cancer by Blocking the SCP3-NANOG Axis

Immunoediting caused by antitumor immunity drives tumor cells to acquire refractory phenotypes. We demonstrated previously that tumor antigen-specific T cells edit these cells such that they become resistant to CTL killing and enrich NANOG^high cancer stem cell-like cells. In this study, we show that synaptonemal complex protein 3 (SCP3), a member of the Cor1 family, is overexpressed in immunoedited cells and upregulates NANOG by hyperactivating the cyclin D1-CDK4/6 axis. The SCP3-cyclin D1-CDK4/6 axis was preserved across various types of human cancer and correlated negatively with progression-free survival of cervical cancer patients. Targeting CDK4/6 with the inhibitor palbociclib reversed multiaggressive phenotypes of SCP3^high immunoedited tumor cells and led to long-term control of the disease. Collectively, our findings establish a firm molecular link of multiaggressiveness among SCP3, NANOG, cyclin D1, and CDK4/6 and identify CDK4/6 inhibitors as actionable drugs for controlling SCP3^high immune-refractory cancer.Significance: These findings reveal cyclin D1-CDK4/6 inhibition as an effective strategy for controlling SCP3^high immune-refractroy cancer. Cancer Res; 78(10); 2638-53. ©2018 AACR.

Profile of buparlisib and its potential in the treatment of breast cancer: evidence to date

Alteration of the phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin signaling pathway is key for the growth and survival of several cancers, including breast cancer. In addition, dysregulation of PI3K signaling may contribute to resistance to several anticancer agents. PI3K inhibitors may, therefore, be effective as antineoplastic therapy. Buparlisib is a potent and highly specific oral inhibitor of the pan-class I PI3K family. Buparlisib specifically inhibits class I PIK3 in the PI3K/AKT kinase signaling pathway in an ATP-competitive manner, thus inhibiting the production of the secondary messenger phosphatidylinositol (3,4,5)-trisphosphate and activation of the PI3K signaling pathway. This may induce inhibition of tumor cell growth and survival in susceptible tumor cell populations. Buparlisib is currently under investigation in patients with a variety of solid tumors, including breast cancer. Buparlisib has been validated as a promising anticancer agent, and tremendous efforts have been taken to develop it. However, buparlisib monotherapy has resulted in humble benefit so far. Results from studies combining buparlisib with different anticancer agents - namely, endocrine therapy, anti-HER2 therapy, and chemotherapy - have showed variable efficacy with consistent substantial toxicity.

XB130 is overexpressed in prostate cancer and involved in cell growth and invasion

XB130 is a cytosolic adaptor protein involved in various physiological processes and oncogenesis of certain malignancies, but its role in the development of prostate cancer remains unclear. In current study, we examined XB130 expression in prostate cancer tissues and found that XB130 expression was remarkably increased in prostate cancer tissues and significantly correlated with increased prostate specific antigen (PSA), free PSA (f-PSA), prostatic acid phosphatase (PAP) and T classification. Patients with highly expressed XB130 had significantly decreased survival, which suggested XB130 as a possible prognostic indicator for prostate cancer. In vitro experiments showed that reduced XB130 expression restrained tumor growth both in vitro and in vivo. Furthermore, XB130 knockdown hindered transition of G1 to S phase in prostate cancer cell line DU145 and LNCap, which might contribute to the inhibition of cellular proliferation. Results from transwell assay demonstrated that downregulation of XB130 may attenuate invasion and metastasis of prostate cancer. Semiquantitative analysis of Western blot suggested that decreased XB130 expression was accompanied by diminished Akt signaling and EMT process. Thus, above observations suggest that XB130 may be a novel molecular marker and potent therapeutic target for prostate cancer.

Estrogen Receptor-Positive Breast Cancer: Exploiting Signaling Pathways Implicated in Endocrine Resistance

Advancements in molecular profiling and endocrine therapy (ET) have led to more focused clinical attention on precision medicine. These advances have expanded our understanding of breast cancer (BC) pathogenesis and hold promising implications for the future of therapy. The estrogen receptor-α is a predominant endocrine regulatory protein in the breast and in estrogen-induced BC. Successful targeting of proteins and genes within estrogen receptor (ER) nuclear and nonnuclear pathways remains a clinical goal. Several classes of antiestrogenic agents are available for patients with early, advanced, or metastatic BC, including selective ER modulators, aromatase inhibitors, and a selective ER degrader. Clinical development is focused upon characterizing the efficacy and tolerability of inhibitors that target the phosphatidylinositol 3 kinase (PI3K)/akt murine thymoma viral oncogene (AKT)/mammalian target of rapamycin inhibitor (mTOR) signaling pathway or the cyclin-dependent kinase 4/6 (CDK4/6) cell cycle pathway in women with hormone receptor-positive, human epidermal growth receptor 2-negative BC who have demonstrated disease recurrence or progression. De novo and acquired resistance remain a major challenge for women with BC receiving antiestrogenic therapy. Therefore, sequential combination of targeted ET is preferred in these patients, and the ever-increasing understanding of resistance mechanisms may better inform the selection of future therapy. This review describes the intricate roles of the PI3K/AKT/mTOR and CDK4/6 pathways in intracellular signaling and the use of endocrine and endocrine-based combination therapy in BC.

IMPLICATIONS FOR PRACTICE

The foundational strategy for treating hormone receptor-positive, human epidermal growth receptor 2-negative, advanced breast cancer includes the use of endocrine therapy either alone or in combination with targeted agents. The use of combination therapy aims to downregulate cell-signaling pathways with the intent of minimizing cellular "crosstalk," which can otherwise result in continued tumorigenesis or progression through redundant pathways. This review provides the clinician with the molecular rationale and clinical evidence for these treatments and refers to evidence-based guidelines to inform the decision-making process.

PI3K in cancer: its structure, activation modes and role in shaping tumor microenvironment

The role of PI3K in cancer has been well established, and mutations of PIK3CA, the gene coding for catalytic subunit p110α of PI3K, are found in approximately 30% human cancers. The hyperactivated PI3K pathway plays a central role in the tumor cell activities such as proliferation, differentiation, chemotaxis, survival, trafficking and metabolism. Besides, PI3K pathway is involved in the regulation of angiogenesis and the host immune response against cancer. Therefore, the inhibition of PI3K pathway can yield multifaceted tumor cell-extrinsic effects that may synergize with chemotherapy, and more importantly, with the newly revived immunotherapy. Here, we review the structures and activation modes of PI3Ks and its implications in angiogenesis, extracellular matrix remodeling and tumor immunity.

Efficacy of buparlisib in treating breast cancer

INTRODUCTION

Breast cancer is the most frequent cancer in women. Despite a decline in breast cancer mortality, prognosis of advanced breast cancer remains poor. In a desperate need to improve breast cancer outcomes, newer agents that target molecular pathways are being tested. Deregulation of the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) is frequently found in breast cancer. This can lead to resistance of endocrine therapy and anti-HER2 therapies. Targeting this pathway may restore sensitivity to these compounds. Buparlisib (BKM-120) is an orally active pan-PI3K inhibitor evaluated in different tumor types. Areas covered: Buparlisib is one of the most investigated PI3K inhibitors. Preclinical and clinical studies of buparlisib in breast cancer are analyzed and discussed. This article reviews the status of buparlisib, completed and ongoing trials, and its safety. Expert opinion: PI3K inhibitors show promising results in breast cancer. However, we raise a number of issues including the identification of biomarkers to predict treatment response and strategies to counteract resistance. Moreover, its toxicity profile could limit its extensive use.

A map of the subcellular distribution of phosphoinositides in the erythrocytic cycle of the malaria parasite Plasmodium falciparum

Despite representing a small percentage of the cellular lipids of eukaryotic cells, phosphoinositides (PIPs) are critical in various processes such as intracellular trafficking and signal transduction. Central to their various functions is the differential distribution of PIP species to specific membrane compartments through the actions of kinases, phosphatases and lipases. Despite their importance in the malaria parasite lifecycle, the subcellular distribution of most PIP species in this organism is still unknown. We here localise several species of PIPs throughout the erythrocytic cycle of Plasmodium falciparum. We show that PI3P is mostly found at the apicoplast and the membrane of the food vacuole, that PI4P associates with the Golgi apparatus and the plasma membrane and that PI(4,5)P2, in addition to being detected at the plasma membrane, labels some cavity-like spherical structures. Finally, we show that the elusive PI5P localises to the plasma membrane, the nucleus and potentially to the transitional endoplasmic reticulum (ER). Our map of the subcellular distribution of PIP species in P. falciparum will be a useful tool to shed light on the dynamics of these lipids in this deadly parasite.

P85 regulates neuronal migration through affecting neuronal morphology during mouse corticogenesis

In mammalian developing embryonic cortex, projection neurons migrate from the ventricular zone to the cortical plate, guided by radial glial cells with a transformation between bipolar and multipolar morphology. Previous studies have demonstrated that the PI3K-Akt-mTOR signal plays a critical role in brain development. However, the function of P85 in cortical development is still unclear. In the present study, we found that overexpression of P85 impaired cortical neuronal migration. Using in utero electroporation, we revealed that the length of the leading process in P85 overexpressed neurons became shorter than that in the control group but with more branches. Using markers for new-born neurons, we further found that overexpression of P85 did not affect the ultimate fate of these cortical neurons. These findings indicated that the P85 subunit plays an essential role in neuronal migration and neuronal morphology during mouse corticogenesis.

Mechanism of resistance to endocrine therapy in breast cancer: the important role of PI3K/Akt/mTOR in estrogen receptor-positive, HER2-negative breast cancer

Endocrine therapy is a crucial treatment for estrogen receptor-positive (ER+) breast cancer, with proven clinical benefits. However, adaptive mechanisms emerge in the tumor, causing resistance to endocrine therapy. A better understanding of resistance mechanisms is needed to overcome this problem and to develop new, precise treatment strategies. Accumulating genetic and cancer biological studies demonstrate the importance of understanding the PI3K/Akt/mTOR and CDK4/6/RB pathways in ER+ HER2- breast cancer. PIK3CA (which encodes phosphatidylinositol-4, 5-bisphosphate 3-kinase catalytic subunit α) is frequently mutated in breast cancer, and 30% of advanced ER+ HER2- breast cancers have an activating PIK3CA mutation. AKT1 mutations (E17K) have been found in 1.4-8% of breast cancer patients. ER+ breast cancer patients preferentially demonstrate gain of CCND1 (cyclin D1; 58% in luminal B vs. 29% in luminal A) and CDK4 (25% in luminal B vs. 14% in luminal A) and loss of CDKN2A (p16) and CDKN2C (p18), which are negatively regulated with the cell cycle and are correlated with the CDK4/6/RB pathway. Abnormalities in PI3K/Akt/mTOR and CDK4/6/RB pathways due to genetic alterations result in deregulated kinase activity and malignant transformation. This review focuses on the recent reports of the essential role of PI3K/Akt/mTOR and CDK4/6/RB pathways in ER+ HER2- breast cancer.

Dual or multi-targeting inhibitors: The next generation anticancer agents

Dual-targeting/Multi-targeting of oncoproteins by a single drug molecule represents an efficient, logical and alternative approach to drug combinations. An increasing interest in this approach is indicated by a steady upsurge in the number of articles on targeting dual/multi proteins published in the last 5 years. Combining different inhibitors that destiny specific single target is the standard treatment for cancer. A new generation of dual or multi-targeting drugs is emerging, where a single chemical entity can act on multiple molecular targets. Dual/Multi-targeting agents are beneficial for solving limited efficiencies, poor safety and resistant profiles of an individual target. Designing dual/multi-target inhibitors with predefined biological profiles present a challenge. The latest advances in bioinformatic tools and the availability of detailed structural information of target proteins have shown a way of discovering multi-targeting molecules. This neoteric artifice that amalgamates the molecular docking of small molecules with protein-based common pharmacophore to design multi-targeting inhibitors is gaining great importance in anticancer drug discovery. Current review focus on the discoveries of dual targeting agents in cancer therapy using rational, computational, proteomic, bioinformatics and polypharmacological approach that enables the discovery and rational design of effective and safe multi-target anticancer agents.

PI3K/mTOR Inhibitors in the Treatment of Luminal Breast Cancer. Why, When and to Whom?

Estrogen receptor (ER) signaling represents the main driver of tumor growth and survival in luminal breast cancer (BC). Despite the efficacy of endocrine agents, many patients with luminal BC do not respond to endocrine therapy and many others develop endocrine resistance over time, due to the activation of escape pathways such as the PI3K/AKT/mTOR signaling. Several clinical trials have demonstrated the efficacy of mTOR and PI3K inhibitors in overcoming endocrine resistance in hormone receptor-positive human epidermal growth factor receptor 2 (HER2)-negative metastatic BC (MBC) patients. Nevertheless, to date, everolimus is the only agent targeting the PI3K/mTOR pathway that has been approved for clinical use. Recently, the introduction of CDK 4/6 inhibitors into clinical practice has significantly changed the therapeutic scenarios in luminal MBC. In the absence of direct comparisons among the new treatment combinations and predictive biomarkers of response, the choice of optimal therapeutic algorithms is very challenging. Future trials should focus on identifying more effective and safe combination therapies and defining the best treatment sequences in luminal BC.

Pan-phosphatidylinositol 3-kinase inhibition with buparlisib in patients with relapsed or refractory non-Hodgkin lymphoma

Activation of the phosphatidylinositol 3-kinase/mechanistic target of rapamycin pathway plays a role in the pathogenesis of non-Hodgkin lymphoma. This multicenter, open-label phase 2 study evaluated buparlisib (BKM120), a pan-class I phosphatidylinositol 3-kinase inhibitor, in patients with relapsed or refractory non-Hodgkin lymphoma. Three separate cohorts of patients (with diffuse large B-cell lymphoma, mantle cell lymphoma, or follicular lymphoma) received buparlisib 100 mg once daily until progression, intolerance, or withdrawal of consent. The primary endpoint was overall response rate based on a 6-month best overall response by cohort; secondary endpoints included progression-free survival, duration of response, overall survival, safety, and tolerability. Overall, 72 patients (26 with diffuse large B-cell lymphoma, 22 with mantle cell lymphoma, and 24 with follicular lymphoma) were treated. The overall response rates were 11.5%, 22.7%, and 25.0% in patients with diffuse large B-cell lymphoma, mantle cell lymphoma, and follicular lymphoma, respectively; two patients (one each with diffuse large B-cell lymphoma and mantle cell lymphoma) achieved a complete response. The most frequently reported (>20%) adverse events of any grade in the population in which safety was studied were hyperglycemia, fatigue, and nausea (36.1% each), depression (29.2%), diarrhea (27.8%), and anxiety (25.0%). The most common grade 3/4 adverse events included hyperglycemia (11.1%) and neutropenia (5.6%). Buparlisib showed activity in relapsed or refractory non-Hodgkin lymphoma, with disease stabilization and sustained tumor burden reduction in some patients, and acceptable toxicity. Development of mechanism-based combination regimens with buparlisib is warranted. (This study was funded by Novartis Pharmaceuticals Corporation and registered with ClinicalTrials.gov number, NCT01693614).

Endometrial Carcinoma: Specific Targeted Pathways

Endometrial cancer (EC) is the most common gynecologic malignancy in the western world with more than 280,000 cases per year worldwide. Prognosis for EC at early stages, when primary surgical resection is the most common initial treatment, is excellent. Five-year survival rate is around 70 %.Several molecular alterations have been described in the different types of EC. They occur in genes involved in important signaling pathways. In this chapter, we will review the most relevant altered pathways in EC, including PI3K/AKT/mTOR, RAS-RAF-MEK-ERK, Tyrosine kinase, WNT/β-Catenin, cell cycle, and TGF-β signaling pathways. At the end of the chapter, the most significant clinical trials will be briefly discussed.This information is important to identify specific targets for therapy.

Trigonostemon reidioides modulates endothelial cell proliferation, migration and tube formation via downregulation of the Akt signaling pathway

Trigonostemon reidi`oides (TR) is used as a Thai traditional medicine for the treatment of drug addiction, asthma, food poisoning, constipation and snake bites. The present study investigated the effects and molecular mechanisms of the ethanolic extract of TR (ETR) on mitogen-induced human umbilical vein endothelial cells (HUVECs) responses, proliferation, adhesion, migration and tube formation. ETR treatment inhibited mitogen-induced HUVEC proliferation by downregulation of cell cycle-associated proteins, including cyclins and cyclin-dependent kinases, which induced retinoblastoma protein hypophosphorylation. The present study also demonstrated that ETR treatment suppressed mitogen-induced HUVEC adhesion, migration, invasion and tube formation, and that these anti-angiogenic activities were mediated by inactivation of mitogen-induced Akt and matrix metalloproteinase (MMP)-2, but not of extracellular signal-regulated kinase, p70 ribosomal S6 kinase or MMP-9. Collectively, the results of the present study suggested pharmacological functions and molecular mechanisms of ETR in regulating endothelial cell fates, and supported further evaluation and development of ETR as a potential therapeutic agent for the treatment and prevention of angiogenesis-associated diseases, including cancer.

Scutellaria barbata D. Don inhibits 5-fluorouracil resistance in colorectal cancer by regulating PI3K/AKT pathway

5-Fluorouracil (5-FU) resistance or multidrug resistance (MDR) has become a major obstacle in clinical treatment of cancers including colorectal cancer (CRC). Aberrant activation of phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT) pathway may lead to unlimited growth and chemoresistance in CRC cells, which thus could be a promising therapeutic target. As a long-term used traditional Chinese folk-medicine, Scutellaria barbata D. Don (SB) processes specific anticancer activity, but its activity against cancer chemoresistance is less known. Therefore, using a 5-FU-resistant CRC cell line HCT-8/5-FU, in this study we evaluated the therapeutic efficacy of the ethanol extracts of SB (EESB) against 5-FU resistance and explored the possible molecular mechanisms. We found that EESB significantly suppressed proliferation and promoted apoptosis in HCT-8/5-FU cells. Additionally, EESB displayed remarkable effect enhancing the retention of the ATP-binding cassette (ABC) transporter substrate, rhodamine‑123 (Rh‑123) in HCT-8/5-FU cells. Furthermore, EESB obviously downregulated the expression of cyclin D1, Bcl-2 and ABCG2, while upregulated p21 and Bax expression. Moreover, EESB showed a prominent suppressive effect on the activation of PI3K/AKT pathway. The findings suggested that Scutellaria barbata D. Don was able to inhibit chemoresistance in colorectal cancer by suppression of the PI3K/AKT pathway.

ErbB2-positive mammary tumors can escape PI3K-p110α loss through downregulation of the Pten tumor suppressor

Breast cancer is the most common cancer among women and 30% will be diagnosed with an ErbB2-positive cancer. Forty percent of ErbB2-positive breast tumors have an activating mutation in p110α, a catalytic subunit of phosphoinositide 3-kinase (PI3K). Clinical and experimental data show that breast tumors treated with a p110α-specific inhibitor often circumvent inhibition and resume growth. To understand this mechanism of resistance, we crossed a p110α conditional (p110αflx/flx) mouse model with mice that overexpresses the ErbB2/Neu-IRES-Cre transgene (NIC) specifically in the mammary epithelium. Although mammary-specific deletion of p110α dramatically delays tumor onset, tumors eventually arise and are dependent on p110β. Through biochemical analyses we find that a proportion of p110α-deficient tumors (23%) display downregulation of the Pten tumor suppressor. We further demonstrate that loss of one allele of PTEN is sufficient to shift isoform dependency from p110α to p110β in vivo. These results provide insight into the molecular mechanism by which ErbB2-positive breast cancer escapes p110α inhibition.

Protease-activated receptor-2 promotes kidney tubular epithelial inflammation by inhibiting autophagy via the PI3K/Akt/mTOR signalling pathway

Protease-activated receptor-2 (PAR2), which belongs to a specific class of the G-protein-coupled receptors, is central to several inflammation processes. However, the precise molecular mechanism involved remains undefined. Autophagy has been previously shown to affect inflammation. In the present study, we examine the effect of PAR2 on kidney tubular epithelial autophagy and on autophagy-related inflammation and reveal the underlying mechanism involved. Autophagic activity and levels of autophagic marker LC3 were examined in human kidney tubular epithelial cells with PAR2 knockdown or overexpression. We administered the mammalian target of rapamycin (mTOR) inhibitor (rapamycin) or activator (MHY1485) to investigate the function of the phosphoinositide 3-kinase (PI3K)/Akt/mTOR pathway. We also used transforming growth factor-β1 (TGF-β1)-induced HK-2 cell inflammation models to investigate the role of PAR2-associated autophagy in kidney tubular epithelial inflammation. PAR2 antagonist and rapamycin were administered to mice after unilateral ureteral obstruction to detect the correlations between PAR2, autophagy, and inflammation. Our results show that PAR2 overexpression in HK-2 cells led to a greater reduction in autophagy via the PI3K/Akt/mTOR pathway activation and induces autophagy-related inflammation. Meanwhile, a knockdown of PAR2 via PAR2 RNAi transfection greatly increased autophagy and alleviated autophagy-associated inflammation. In unilateral ureteral obstruction (UUO) kidneys, PAR2 antagonist treatment greatly attenuated renal inflammation and interstitial injury by enhancing autophagy. Moreover, inhibition of mTOR, rapa, markedly increased autophagy and inhibited the UUO-induced inflammation. We conclude that PAR2 induces kidney tubular epithelial inflammation by inhibiting autophagy via the PI3K/Akt/mTOR signalling pathway. Our results are suggestive that PAR2 inhibition may play a role in the treatment of diseases with increased inflammatory responses in renal systems.

High PHLPP1 expression levels predicts longer time of acquired resistance to EGFR tyrosine kinase inhibitors in patients with lung adenocarcinoma

Background

In spite of an initial good response to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) in lung adenocarcinoma patients, resistance to treatment eventually occurs. Epidermal growth factor receptor (EGFR) activation stimulates Ras/Raf/Erk/MAPK and influences PI3K/Akt pathways, respectively. PHLPP negatively regulates PI3K/Akt and the RAF/RAS/ERK signaling pathways. Our study aimed to investigate the association between PH domain leucine-rich-repeats protein phosphatase (PHLPP) expression levels and the acquired resistance to EGFR TKIs in lung adenocarcinoma.

Results

High expression levels of PHLPP1 and PHLPP2 were detected in 69.3% and 61.3%, respectively, of patients with lung adenocarcinoma. Patients with high expression levels of PHLPP1 showed significantly longer median progression-free survival and overall survival than those with low expression levels of PHLPP1 (29 months versus 11 months, and 36 months versus 19 months respectively) (p = 0.0050 and p = 0.0052). PHLPP1, but not PHLPP2, protein expression levels was negatively correlated with p-Akt (473) and p-Erk1/2. The PHLPP1 expression levels were correlated with Progression-free survival and overall survival (p = 0.001 and p = 0.000).

Materials and Methods

We recruited 75 patients with advanced lung adenocarcinoma receiving EGFR TKIs treatment. The expression levels of PHLPP1, PHLPP2, p-AKT(S473) and p-ERK1/2 were assessed using tissue immunostaining. The association of PHLPP expression levels with clinicopathological parameters and disease prognosis was analyzed.

Conclusions

This study suggests that high expression levels of PHLPP1 predict a better survival from target therapy and a longer time of acquired resistance to EGFR TKIs in patients with lung adenocarcinoma.

PI3K p85α Subunit-deficient Macrophages Protect Mice from Acute Colitis due to the Enhancement of IL-10 Production

We investigated the role of the PI3K p85α subunit in the development of acute colitis with a focus on intestinal macrophages. Experimental acute colitis was induced using 3% dextran sulfate sodium (DSS) in drinking water for 7 days. The severity of DSS-induced acute colitis was significantly attenuated in p85α hetero-deficient (p85α+/−) mice compared with WT mice. The expression of proinflammatory mediators in intestinal macrophages isolated from the inflamed colonic mucosa was significantly suppressed in p85α+/− colitis mice compared with WT colitis mice. Interestingly, we found that bone marrow-derived macrophages (BMDMs) from p85α+/− mice produced a significantly higher amount of IL-10 than BMDMs from WT mice. The adoptive transfer of p85α+/− BMDMs, but not WT BMDMs, significantly improved the severity in WT colitis mice, and this effect was reversed by anti-IL-10 antibody. Furthermore, the expression of IL-10 in the intestinal macrophages of p85α+/− normal colonic mucosa was significantly higher than that in the intestinal macrophages of WT normal colonic mucosa. The present results demonstrate that p85α+/− mice exhibit a reduced susceptibility to DSS-induced acute colitis. Our study suggests that a deficiency of PI3K p85α enhances the production of IL-10 in intestinal macrophages, thereby suppressing the development of DSS-induced acute colitis.

Clinical use of lenvatinib in combination with everolimus for the treatment of advanced renal cell carcinoma

INTRODUCTION

Renal cell carcinoma (RCC) represents 2%-3% of all cancers in adults, and its pathogenesis is mainly related to altered cellular response to hypoxia. Lenvatinib, a novel multitarget tyrosine kinase inhibitor (TKI), represents a therapeutic option, in combination with mammalian target of rapamycin (mTOR) inhibitor everolimus, for the treatment of metastatic RCC (mRCC).

AIM

The objective of this article is to review the evidence about the treatment of mRCC with combination of lenvatinib plus everolimus.

EVIDENCE REVIEW

Phase I studies supported clinical activity of lenvatinib in mRCC. A randomized, Phase II, open-label, multicenter trial demonstrated the clinical efficacy of combination treatment with lenvatinib plus everolimus in patients with progressive mRCC after prior therapy with TKI. Median progression-free survival was improved by 9 months with the combination therapy compared to the single-agent everolimus, with an overall response rate of 43% for the experimental regimen. Lenvatinib plus everolimus appeared to be slightly less toxic than single-agent lenvatinib and more toxic than single-agent everolimus; grade 3-4 adverse events occurred in 71% of patients. Currently, lenvatinib plus everolimus has US Food and Drug Administration approval for its use in mRCC after failure of previous treatment with TKI.

CONCLUSION

The combination therapy with lenvatinib plus everolimus might be a promising choice for second-line treatment of mRCC patients. Based on the results of the Phase II trial, it is possible to speculate that the combination therapy could be appropriate for patients with high disease burden or strongly symptomatic patients.

Combining properties of different classes of PI3Kα inhibitors to understand the molecular features that confer selectivity

Phosphoinositide 3-kinases (PI3Ks) are major regulators of many cellular functions, and hyperactivation of PI3K cell signalling pathways is a major target for anticancer drug discovery. PI3Kα is the isoform most implicated in cancer, and our aim is to selectively inhibit this isoform, which may be more beneficial than concurrent inhibition of all Class I PI3Ks. We have used structure-guided design to merge high-selectivity and high-affinity characteristics found in existing compounds. Molecular docking, including the prediction of water-mediated interactions, was used to model interactions between the ligands and the PI3Kα affinity pocket. Inhibition was tested using lipid kinase assays, and active compounds were tested for effects on PI3K cell signalling. The first-generation compounds synthesized had IC₅₀ (half maximal inhibitory concentration) values >4 μM for PI3Kα yet were selective for PI3Kα over the other Class I isoforms (β, δ and γ). The second-generation compounds explored were predicted to better engage the affinity pocket through direct and water-mediated interactions with the enzyme, and the IC₅₀ values decreased by ∼30-fold. Cell signalling analysis showed that some of the new PI3Kα inhibitors were more active in the H1047R mutant bearing cell lines SK-OV-3 and T47D, compared with the E545K mutant harbouring MCF-7 cell line. In conclusion, we have used a structure-based design approach to combine features from two different compound classes to create new PI3Kα-selective inhibitors. This provides new insights into the contribution of different chemical units and interactions with different parts of the active site to the selectivity and potency of PI3Kα inhibitors.