Phosphatidylinositol 3-kinase Signaling Research Articles

BYL719 reverses gefitinib-resistance induced by PI3K/AKT activation in non-small cell lung cancer cells

Non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation often obtain de novo resistance or develop secondary resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs), which restricts the clinical benefit for the patients. The activation of phosphatidylinositol 3-kinase (PI3K)/AKT signal pathway is one of the most important mechanisms for the EGFR-TKIs resistance beyond T790M mutation. There are currently no drugs simultaneously targeting EGFR and PI3K signal pathways, and combination of these two pathway inhibitors may be a possible strategy to reverse theses resistances. To test whether this combinational strategy works, we investigated the therapeutic effects and mechanisms of combining BYL719, a PI3Kα inhibitor, with gefitinib, an EGFR-TKI inhibitor in EGFR-TKIs resistance NSCLC models induced by PI3K/AKT activation. Our results demonstrated that PIK3CA mutated cells showed increased growth rate and less sensitive or even resistant to gefitinib, associated with increased PI3K/AKT expression. The combination of BYL719 and gefitinib resulted in synergistic effect compared with the single agents alone in EGFR-mutated NSCLC cells with PI3K/AKT activation. The inhibition of AKT phosphorylation by BYL719 increased the antitumor efficacy of gefitinib in these cell lines. Moreover, the combined effect and mechanism of gefitinib and BYL719 were also confirmed in the NSCLC cells and patient-derived organoids under 3D culture condition, as well as in vivo. Taken together, the data indicate that PIK3CA mutation induces more aggressive growth and gefitinib resistance in NSCLC cells, and the combination treatment with gefitinib and BYL719 is a promising therapeutic approach to overcoming EGFR-TKIs resistance induced by PI3K/AKT activation.

Unraveling the molecular landscape: a comparative analysis of PI3K and MAPK signaling pathways in plasmablastic lymphoma and diffuse large B-cell lymphoma with therapeutic implications

Plasmablastic lymphoma (PBL) is a rare and aggressive subtype of non-Hodgkin lymphoma that shares features with diffuse large B-cell lymphoma (DLBCL). While significant progress has been made in treating DLBCL, the prognosis for PBL remains poor, highlighting the need to identify new therapeutic targets. Using RNA expression analysis, we compared the expression of genes involved in the phosphatidylinositol-3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) signaling pathways between PBL and DLBCL. We used critical PI3K (n=201) and MAPK (n=57) signaling probe sets to achieve this objective. Our results demonstrate unique molecular mechanisms underlying PBL pathogenesis compared to DLBCL, particularly within the PI3K and MAPK signaling pathways. We found that elevated STAT3 expression in PBL correlates with hyperactive MAPK and PI3K pathways, unlike DLBCL. Additionally, the hyperactivation of the PI3K signaling axis in PBL is unrelated to B-cell receptoror phosphatase and tensin homologactivity, indicating a distinct mechanism compared to DLBCL. Furthermore, we observed unique activation patterns in MAPK pathways between PBL and DLBCL, with PBL exhibiting high expression of the neurotrophic tyrosine kinase receptor (NTKR) family, specifically NTRK1 and NTRK2 genes, which have therapeutic potential. We also found that neither human immunodeficiency virus nor Epstein-Barr virus infection influences gene expression profiles linked to PI3K and MAPK signaling in PBL. These findings could lead to adapting targeted therapies developed for DLBCL to address the specific needs of PBL patients better and contribute to developing novel, targeted therapeutic strategies to improve patient outcomes.

Angiogenic Activity and Mechanism for Bisphenols on Endothelial Cell and Mouse: Evidence of a Structural-Selective Effect.

Increased epidemiological evidence indicates the association of bisphenol exposure with human vascular disorders, while the underlying mechanism has not been clarified. Here, we sought to unveil the potential angiogenic effect and the underlying mechanism of bisphenols with different structural features using endothelial cells treated with an environmentally relevant concentration of bisphenols (range: 1 nM to 10 μM) and a C57BL/6 mouse model fed with doses of 0.002, 0.02, 2, and 20 mg/kg BW/day for 5 weeks. Bisphenol A (BPA) and bisphenol S (BPS) at a 1 nM level significantly increased tube formation by 45.1 and 30.2% and induced the microvessel sprouting, while tube length and microvessel sprouting were significantly inhibited by 37.2 and 55.7% after exposure to tetrabromobisphenol S (TBBPS) at 1 μM, respectively. Mechanistically, TBBPA and TBBPS significantly inhibited the interaction between phosphatidylinositol 3-kinase (PI3K) and thyroid receptor (TR), while BPA and BPS favored the interaction between PI3K and estrogen receptor (ER), resulting in abnormal PI3K signaling with consequent distinct angiogenic activity. BPA- and BPS-induced pro-angiogenic effects and TBBPS showed anti-angiogenic effects due to their distinct disruption on the TR/ER-PI3K pathway. Our work provided new evidence and mechanistic insight on the angiogenic activity of bisphenols and expanded the scope of endocrine disruptors with interference in vascular homeostasis.

1780-P: Assessment of Toll-Like Receptor Expression and Signaling in Islets under Metabolic and Inflammatory Conditions

Pancreatic beta cells undergoing metabolic and inflammatory stress express islet-derived cytokines or “isletokines” which can induce immune cell infiltration and cellular damage leading to loss of islet cell function. We and others have shown that toll-like receptor (TLR) 4 in islets can mediate metabolic and inflammatory response to DAMPs under diabetic conditions and in islet cell transplantation. Here we show that metabolic and inflammatory conditions result in induction and suppression of expression of multiple members of the TLR family in both MIN6 beta-cell line and mouse islets. Among upregulated TLRs, the endosomal nucleic acid-sensing TLR3 was most highly induced (up to 5 fold) in response to cytokine cocktail IL-1beta, TNF-alpha, and IFN-gamma in the presence of high glucose. Induction of TLR3 expression was blocked by PI3 kinase inhibitor wortmannin and unaffected by mTOR inhibitor rampamycin, calcineurin inhibitor FK506, and NF-κB inhibitor BMS345541. Immunoblot analyses confirmed that TLR3 but not TLR4 protein expression was wortmannin sensitive. These data indicate that TLR3 is upregulated by PI3 kinase signaling in islet beta cells in response to inflammatory conditions. As the endosomal TLR3 signaling is known to sense nucleic acids as well as influence glucose homeostasis, we propose that beta cells may sense DNA damage to induce isletokines to mediate local inflammatory responses during metabolic and inflammatory stress. Further investigations are warranted to decipher signaling pathways and molecular targets of TLR3 signaling to alleviate islet inflammation and improve beta-cell function. Disclosure J.D.Mattke: None. B.Naziruddin: None. M.C.Lawrence: None.

Inhibition of the NLRP3 Inflammasome Activation/Assembly through the Activation of the PI3K Pathway by Naloxone Protects Neural Stem Cells from Ischemic Condition.

Naloxone is a well-known opioid antagonist and has been suggested to have neuroprotective effects in cerebral ischemia. We investigated whether naloxone exhibits anti-inflammatory and neuroprotective effects in neural stem cells (NSCs) injured by oxygen-glucose deprivation (OGD), whether it affects the NOD-like receptor protein 3 (NLRP3) inflammasome activation/assembly, and whether the role of the phosphatidylinositol 3-kinase (PI3K) pathway is important in the control of NLRP3 inflammasome activation/assembly by naloxone. Primary cultured NSCs were subjected to OGD and treated with different concentrations of naloxone. Cell viability, proliferation, and the intracellular signaling proteins associated with the PI3K pathway and NLRP3 inflammasome activation/assembly were evaluated in OGD-injured NSCs. OGD significantly reduced survival, proliferation, and migration and increased apoptosis of NSCs. However, treatment with naloxone significantly restored survival, proliferation, and migration and decreased apoptosis of NSCs. Moreover, OGD markedly increased NLRP3 inflammasome activation/assembly and cleaved caspase-1 and interleukin-1β levels in NSCs, but naloxone significantly attenuated these effects. These neuroprotective and anti-inflammatory effects of naloxone were eliminated when cells were treated with PI3K inhibitors. Our results suggest that NLRP3 inflammasome is a potential therapeutic target and that naloxone reduces ischemic injury in NSCs by inhibiting NLRP3 inflammasome activation/assembly mediated by the activation of the PI3K signaling pathway.

LTK and ALK promote neuronal polarity and cortical migration by inhibiting IGF1R activity

The establishment of axon‐dendrite polarity is fundamental for radial migration of neurons, cortical patterning, and formation of neuronal circuits. Here, we show that the receptor tyrosine kinases, Ltk and Alk, are required for proper neuronal polarization. In isolated primary mouse embryonic neurons, the loss of Ltk and/or Alk causes a multiple axon phenotype. In mouse embryos and newborn pups, the absence of Ltk and Alk delays neuronal migration and subsequent cortical patterning. In adult cortices, neurons with aberrant neuronal projections are evident and axon tracts in the corpus callosum are disrupted. Mechanistically, we show that the loss of Alk and Ltk increases the cell‐surface expression and activity of the insulin‐like growth factor 1 receptor (Igf‐1r), which activates downstream PI3 kinase signaling to drive the excess axon phenotype. Our data reveal Ltk and Alk as new regulators of neuronal polarity and migration whose disruption results in behavioral abnormalities.

PTEN Deficiency: a phenocopy phenomenon

BackgroundActivated PI3K delta syndrome 1 (APDS1) is caused by mutations in PI3KCD. The phosphatidylinositol 3-kinase (PI3K) signaling pathway is essential to cell survival, proliferation, and metabolism. PI3K plays a crucial role in the regulation of function and differentiation of immune cells. Phosphatase and tensin homolog (PTEN) serves to antagonize the PI3K pathway. Overlapping immune features of PTEN deficiency and APDS include high IgM, low IgG, increased transitional B cells, specific antibody deficiencies, autoimmunity, and lymphoproliferation. Because PTEN antagonizes PI3K activity, patients with PTEN loss-of-function mutations exhibit a similar phenotype to those with gain-of-function mutations of PI3K and can respond to mTOR inhibition like APDS patients. Overactivation of PI3K due to PTEN deficiency can lead to generalized immune dysregulation. Here we describe a patient with PTEN deficiency who presents as a phenocopy of APDS1 patients. MethodsRetrospective chart review was performed to obtain data on clinical labs of the PTEN deficient patient and APDS1 patients who presented with a similar clinical phenotype. An Epstein-barr virus (EBV) transformed B cell line (BLCL) was created from the patient PBMCs for functional studies to evaluate the PBK/AIKT/mTOR pathway. Patients were consented on an IRB approved protocol. ResultsThe patient was referred to immunology clinic for autoimmune cytopenias (Evan’s syndrome) and hypogammaglobulinemia. WES revealed De novo heterozygous c.406T>C (p.C136R) pathogenic variant in PTEN. Immune profiling showed elevated transitional B cells, increased naïve B cells and a decreased amount of class-switched memory B cells along with hyper IgM and low IgG. An abdominal ultrasound revealed significant splenomegaly with peri-splenic lymphadenopathy and hyper-echoic lesions in the spleen. Functional studies on BLCLs were reserved for confirmation of dysregulated PI3k/AKT/pS6 signaling. The patient was treated with sirolimus and IgG replacement therapy. After sirolimus therapy, lymphoproliferation and splenic findings resolved. DiscussionPTEN deficiency is a clinical and mechanistic phenocopy of APDS1 due to loss of negative regulation by PTEN to control over-activation of PI3 K. While Evan’s syndrome is reported in APDS1 more readily, it is not as prominent in PTEN. Treatment strategies employed for APDS1 and 2 are viable options for controlling the disease manifestations seen in PTEN deficiency.

Acupuncture improves learning and memory ability of posttraumatic stress disorder model rats through epigenetic regulation of microglial phosphatidylinositol 3-kinase pathway.

Microglia express phosphatidylinositol 3-kinase (PI3K) has been implicated in the induction and maintenance of long-term potentiation (LTP) and in hippocampal synaptic plasticity. However, there are few studies on the interference of PI3K signal pathway in microglia. The study goal is to gain a better understanding of the mechanism by which EA affects synapses provides insights into how electroacupuncture (EA) modulates synaptic plasticity in learning and memory. Rat models of posttraumatic stress disorder (PTSD) were used to explore the effects of EA on microglial PI3K pathway, brain-derived neurotrophic factor (BDNF) and LTP, and the target and mechanism underlying the effects of EA on PI3K from the perspective of protein ubiquitination. EA induced microglial BDNF expression by activating the PI3K-AKT pathway, thereby facilitating LTP and synaptic plasticity. EA inhibited lincRNA 02023 to rescue the binding of WWP2 to PTEN, thereby promoting PTEN ubiquitination and degradation. The mechanism of EA improving the learning and memory ability of PTSD rats may be that it can promote the competitive combination of WWP2 and PTEN by inhibiting Linc RNA02023, and then lead to microglial PI3K and its pathway activation, BDNF up-regulation, and finally induce LTP and repair damaged synaptic plasticity.

A potent bioactive fraction against colon cancer from Plectranthus vettiveroides.

This study was designed to investigate the anticancer efficacy of the organic leaf extracts of the plant, Plectranthus vettiveroides (P. vettiveroides), and to analyze the molecular mechanism of the anticancer activity. The leaf extracts were prepared by polarity-graded serial extraction of the dried leaf powder. The cytotoxic effect of the extracts was analyzed by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. The most active ethyl acetate extract was subjected to bioactivity-guided fractionation by column chromatography, which yielded a cytotoxic fraction designated as the P. vettiveroides fraction (PVF). The anticancer property of PVF was confirmed further by clonogenic assay. The mechanism of PVF-induced cell death was analyzed by flow cytometry and fluorescence microscopy. Additionally, the effects of PVF on apoptotic and cell survival pathways were analyzed using western immunoblot analysis. A bioactive fraction PVF, was isolated from the ethyl acetate leaf extract. PVF showed significant anticancer activity against colon cancer cells, whilst normal cells were comparatively less affected. PVF induced strong apoptotic stimuli in colorectal carcinoma cell line HCT116, involving both extrinsic and intrinsic pathways. Investigation into the molecular mechanism of anticancer activity of PVF in HCT116 cells revealed that the fraction activates the pro-apoptotic pathway via tumor suppressor protein 53 (p53) and inhibits the anti-apoptotic pathway by regulating phosphatidylinositol 3-kinase (PI3K) signaling. The findings of this study demonstrate, with mechanism-based evidence, the chemotherapeutic potential of a bioactive fraction PVF, derived from the leaves of the medicinal plant P. vettiveroides against colon cancer.

Integration of non-additive genome-wide association study with a multi-tissue transcriptome analysis of growth and carcass traits in Duroc pigs

Growth and carcass traits are of economic importance in the pig production, which affect pork quality and profitability of finishing pig production. This study used whole-genome and transcriptome sequencing technologies to identify potential candidate genes affecting growth and carcass traits in Duroc pigs. The medium (50–60 k) single nucleotide polymorphism (SNP) arrays of 4 154 Duroc pigs from three populations were imputed to whole-genome sequence data, yielding 10 463 227 markers on 18 autosomes. The dominance heritabilities estimated for growth and carcass traits ranged from 0.000 ± 0.041 to 0.161 ± 0.054. Using non-additive genome-wide association study (GWAS), we identified 80 dominance quantitative trait loci for growth and carcass traits at genome-wide significance (false discovery rate < 5%), 15 of which were also detected in our additive GWAS. After fine mapping, 31 candidate genes for dominance GWAS were annotated, and 8 of them were highlighted that have been previously reported to be associated with growth and development (e.g. SNX14, RELN and ENPP2), autosomal recessive diseases (e.g. AMPH, SNX14, RELN and CACNB4) and immune response (e.g. UNC93B1 and PPM1D). By integrating the lead SNPs with RNA-seq data of 34 pig tissues from the Pig Genotype-Tissue Expression project (https://piggtex.farmgtex.org/), we found that the rs691128548, rs333063869, and rs1110730611 have significantly dominant effects for the expression of SNX14, AMPH and UNC93B1 genes in tissues related to growth and development for pig, respectively. Finally, the identified candidate genes were significantly enriched for biological processes involved in the cell and organ development, lipids catabolic process and phosphatidylinositol 3-kinase signalling (P < 0.05). These results provide new molecular markers for meat production and quality selection of pig as well as basis for deciphering the genetic mechanisms of growth and carcass traits.

Design, Synthesis and Biological Evaluation of 6-(Imidazo[1,2-a]pyridin-6-yl)quinazoline Derivatives as Anticancer Agents via PI3Kα Inhibition

Aberrant expression of the phosphatidylinositol 3-kinase (PI3K) signalling pathway is often associated with tumourigenesis, progression and poor prognosis. Hence, PI3K inhibitors have attracted significant interest for the treatment of cancer. In this study, a series of new 6-(imidazo[1,2-a]pyridin-6-yl)quinazoline derivatives were designed, synthesized and characterized by 1H NMR, 13C NMR and HRMS spectra analyses. In the in vitro anticancer assay, most of the synthetic compounds showed submicromolar inhibitory activity against various tumour cell lines, among which 13k is the most potent compound with IC50 values ranging from 0.09 μΜ to 0.43 μΜ against all the tested cell lines. Moreover, 13k induced cell cycle arrest at G2/M phase and cell apoptosis of HCC827 cells by inhibition of PI3Kα with an IC50 value of 1.94 nM. These results suggested that compound 13k might serve as a lead compound for the development of PI3Kα inhibitor.

Abstract 6301: Post-translational modifications regulate sensitivity to Polatuzumab Vedotin in DLBCL

Abstract Diffuse Large B-Cell Lymphoma (DLBCL) is an aggressive malignancy of which one-third of diagnosed patients ultimately relapse and die. New treatment paradigms for relapsed-refractory patients are needed. Most DLBCL tumors are reliant on signaling through their cell surface B-cell receptor (BCR) mediated by ITAMs on CD79A and CD79B to drive anti-apoptotic NF-kB and PI3 kinase signaling. In order to understand how surface BCR is regulated, we performed whole genome CRISPR screens in 9 DLBCL cell lines in which we sorted for high and low surface CD79B or added the CD79B targeted antibody-drug conjugate Polatuzumab-Vedotin (POLA-V). Strikingly, independent of genetic or cell of origin subtype, sgRNAs encoding the entire N-linked glycosylation pathway and specific sugar modification by addition of galactose and sialic acid were found to be enriched in high CD79B fractions and depleted in POLA-V treated samples compared to control. Further testing showed that removing sialic acid by treating with a small molecule inhibitor of sialic acid, genetic perturbation of golgi sugar transporters SLC35A1 and SLC35A2, or the a2,6 sialyltransferase ST6GAL1 resulted in more surface CD79B antibody binding with no significant change in CD79B protein abundance. The specificity of the effect of sialic acid loss on POLA antibody binding was confirmed by removing cell surface sialic acid with exogenous sialidase and observing increased binding of POLA, but not other therapeutic antibodies like Rituximab or CD19 FMC-63. Loss of SLC35A1, SLC35A2, and ST6GAL1 synergized with POLA-V but not the drug conjugate MMAE alone, showing a BCR dependent mechanism of sialic acid loss on POLA-V sensitization. In a further cell of origin subtype analysis of the germinal center B-cell (GCB) DLBCL cell lines, loss of the E3 ligase KLHL6 was found to synergize with POLA-V. Importantly, KLHL6 is heavily mutated across all germinal center derived malignancies, is more highly expressed in germinal center B-cells than other members of the B-cell lineage, and plays an unknown role in the development of autoimmune diseases. Further work will give evidence for the target of KLHL6 mediated ubiquitination and will show how this gene can drive lymphoma and autoimmune disease development in the germinal center. Citation Format: Sean R. Corcoran, Louis M. Staudt, Daniel Hodson. Post-translational modifications regulate sensitivity to Polatuzumab Vedotin in DLBCL [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6301.

Phosphatidylinositol 3-kinase signaling pathway and inflammatory bowel disease: Current status and future prospects.

Inflammatory bowel disease (IBD) is a chronic life-limiting disease of gastrointestinal tract characterized by widespread enteric inflammation. IBD is a multifactorial disease, and different environmental, microbial, and immune-related factors give rise to the development of disease. Among several factors, the preponderance of pro-inflammatory T helper 17 cells over the anti-inflammatory regulatory T cells augments inflammation in the intestinal mucosa. Prevailing evidence accentuates that PI3K signaling pathway plays a central role in the pathophysiology of the condition by regulating the inflammatory process in the gut mucosa. By recognizing the implications of PI3K in the pathogenesis of IBD, agents that could modulate this pathway have recently been at the focus of research, yielding encouraging results mainly in the experimental IBD models. In this review, we have summarized the recent advances, which may hold the keys to identify novel therapeutic strategies for IBD.

Undernutrition Disrupts Cecal Microbiota and Epithelium Interactions, Epithelial Metabolism, and Immune Responses in a Pregnant Sheep Model.

Undernutrition may change cecal microbiota-epithelium interactions to influence cecal feed fermentation, nutrient absorption and metabolism, and immune function. Sixteen late-gestation Hu-sheep were randomly divided into control (normal feeding) and treatment (feed restriction) groups to establish an undernourished sheep model. Cecal digesta and epithelium were collected to analyze microbiota-host interactions based on 16S rRNA gene and transcriptome sequencing. Results showed that cecal weight and pH were decreased, volatile fatty acids and microbial proteins concentrations were increased, and epithelial morphology was changed upon undernutrition. Undernutrition reduced the diversity, richness, and evenness of cecal microbiota. The relative abundances of cecal genera involved in acetate production (Rikenellaceae dgA-11 gut group, Rikenellaceae RC9 gut group, and Ruminococcus) and negatively correlated with butyrate proportion (Clostridia vadinBB60 group_norank) were decreased, while genera related to butyrate (Oscillospiraceae_uncultured and Peptococcaceae_uncultured) and valerate (Peptococcaceae_uncultured) production were increased in undernourished ewes. These findings were consistent with the decreased molar proportion of acetate and the increased molar proportions of butyrate and valerate. Undernutrition changed the overall transcriptional profile and substance transport and metabolism in cecal epithelium. Undernutrition suppressed extracellular matrix-receptor interaction and intracellular phosphatidyl inositol 3-kinase (PI3K) signaling pathway then disrupted biological processes in cecal epithelium. Moreover, undernutrition repressed phagosome antigen processing and presentation, cytokine-cytokine receptor interaction, and intestinal immune network. In conclusion, undernutrition affected cecal microbial diversity and composition and fermentation parameters, inhibited extracellular matrix-receptor interaction and the PI3K signaling pathway, and then disrupted epithelial proliferation and renewal and intestinal immune functions. Our findings exposed cecal microbiota-host interactions upon undernutrition and contribute to their further exploration. IMPORTANCE Undernutrition is commonly encountered in ruminant production, especially during pregnancy and lactation in females. Undernutrition not only induces metabolic diseases and threatens pregnant mothers' health, but also inhibits fetal growth and development, leading to weakness or even death of fetuses. Cecum works importantly in hindgut fermentation, providing volatile fatty acids and microbial proteins to the organism. Intestinal epithelial tissue plays a role in nutrient absorption and transport, barrier function, and immune function. However, little is known about cecal microbiota and epithelium interactions upon undernutrition. Our findings showed that undernutrition affected bacterial structures and functions, which changed fermentation parameters and energy regimens, and therefore affected the substance transport and metabolism in cecal epithelium. Extracellular matrix-receptor interactions were inhibited, which repressed cecal epithelial morphology and cecal weight via the PI3K signaling pathway and lowered immune response function upon undernutrition. These findings will help in further exploring microbe-host interactions.

PI3k Inhibitors in NHL and CLL: An Unfulfilled Promise.

Phosphatidylinositol 3-kinases (PI3Ks) are a family of intracellular signal transducer enzymes that can attach a phosphate group to the 3'-hydroxyl of the inositol moiety of membrane-embedded phosphatidylinositol (PI). PI3Ks have been shown to play important roles in cell proliferation, growth, survival, motility, and metabolism. Nonetheless, the PI3K pathway has also shown to be overactivated in several tumors, particularly B-cell malignancies. In recent years, the PI3K signaling pathway has become the major focus of substantial drug discovery and development efforts. Selective (PI3K) inhibitors have been approved for the treatment of chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL), and indolent non-Hodgkin lymphomas (iNHL), such as follicular lymphoma and marginal-zone lymphoma. Four selective PI3K inhibitors have received accelerated FDA approvals for the treatment of patients with relapsed/refractory (R/R) CLL and/or iNHL based mainly on single-arm Phase II studies: Idelalisib (PI3K-δ inhibitor), copanlisib (dual PI3K-α and PI3K-δ inhibitor), duvelisib (dual PI3K-γ and PI3K-δ inhibitor), and umbralisib (dual PI3Kδ and CK1ε inhibitor). Conversely, recent interim results of randomized control trials (RCTs) involving some of these agents, showed a worrisome trend of decrease in overall survival (OS), and an increase in fatal and severe adverse effects, in comparison with patients in the control arms. Consequently, the class of PI3K inhibitors came under scrutiny, with an FDA expert panel voting on April 21, 2022, recommending that future FDA approvals of PI3K inhibitors be supported by randomized data, rather than single-arm data only, and further discontinuing the use of almost all the PI3K inhibitors in hematologic malignancies. As we believe further research is needed to help potentialize PI3K inhibitors by improving their safety profiles, this mini-review aims at revisiting the clinical successes, the failures, and the promising aspect of this class of drugs, while presenting possible ways that could benefit its successful development.

Repeated exposure to 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP) accelerates ligand-independent activation of estrogen receptors in long-term estradiol-deprived MCF-7 cells

It was previously identified that there may be an active metabolite of bisphenol A (BPA), 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP). An in vitro system was developed to detect MBP toxicity to the Michigan Cancer Foundation-7 (MCF-7) cells that had been repeatedly exposed to a low dose of the metabolite. MBP profoundly activated estrogen receptor (ER)-dependent transcription as a ligand, with an EC50 of 2.8 nM. Women are continuously exposed to numerous estrogenic environmental chemicals; but their susceptibility to these chemicals may be significantly altered after menopause. Long-term estrogen-deprived (LTED) cells, which display ligand-independent ER activation, are a postmenopausal breast cancer model derived from MCF-7 cells. In this study, we investigated the estrogenic effects of MBP on LTED cells in a repeated exposure in vitro model. The results suggest that i) nanomolar levels of MBP reciprocally disrupt the balanced expression of ERα and ERβ proteins, leading to the dominant expression of ERβ, ii) MBP stimulates ERs-mediated transcription without acting as an ERβ ligand, and iii) MBP utilizes mitogen-activated protein kinase and phosphatidylinositol-3 kinase signaling to evoke its estrogenic action. Moreover, the repeated exposure strategy was effective for detecting low-dose estrogenic-like effects caused by MBP in LTED cells.

GPR41 Regulates the Proliferation of BRECs via the PIK3-AKT-mTOR Pathway

Short-chain fatty acids (SCFAs) play a pivotal role in regulating the proliferation and development of bovine rumen epithelial cells (BRECs). G protein-coupled receptor 41 (GPR41) is involved in the signal transduction in BRECs as a receptor for SCFAs. Nevertheless, the impact of GPR41 on the proliferation of BRECs has not been reported. The results of this research showed that the knockdown of GPR41 (GRP41KD) decreased BRECs proliferation compared with the wild-type BRECs (WT) (p < 0.001). The RNA sequencing (RNA-seq) analysis showed that the gene expression profiles differed between WT and GPR41KD BRECs, with the major differential genes enriched in phosphatidylinositol 3-kinase (PIK3) signaling, cell cycle, and amino acid transport pathways (p < 0.05). The transcriptome data were further validated by Western blot and qRT-PCR. It was evident that the GPR41KD BRECs downregulated the level of the PIK3-Protein kinase B (AKT)-mammalian target of the rapamycin (mTOR) signaling pathway core genes, such as PIK3, AKT, eukaryotic translation initiation factor 4E binding protein 1 (4EBP1) and mTOR contrasted with the WT cells (p < 0.01). Furthermore, the GPR41KD BRECs downregulated the level of Cyclin D2 p < 0.001) and Cyclin E2 (p < 0.05) compared with the WT cells. Therefore, it was proposed that GPR41 may affect the proliferation of BRECs by mediating the PIK3-AKT-mTOR signaling pathway.

Tumor-Derived Oxidative Stress Triggers Ovarian Follicle Loss in Breast Cancer

Breast cancer is a common indication for ovarian cryopreservation. However, whether the grafting ovarian tissue meets functional requirements, as well as the need for additional interventions, remains unclear. The current study demonstrates abnormal serum hormones in breast cancer in humans and breast cancer cell line-derived tumor-bearing mice, and for the first time shows tumor-induced loss of primordial and growing follicles, and the number of follicles being lost to either growth or atresia. A gene signature of tumor-bearing mice demonstrates the disturbed regulatory network of steroidogenesis, which links to mitochondria dysfunction in oocytes and granulosa cells via the phosphatidylinositol 3-kinase signaling pathway. Notably, increased reactive oxygen species were identified in serum and ovarian tissues in tumor-bearing mice. Furthermore, supplementation withvitamin C promoted follicular quiescence, repairing tumor-induced follicle loss via inactivation of the phosphatidylinositol 3-kinase-Akt-mammalian target of rapamycin pathway, indicating the potential ofantioxidants as a fertility therapy to achieve higher numbers of healthy follicles ready for ovarian cryopreservation.

Binding and selectivity studies of phosphatidylinositol 3-kinase (PI3K) inhibitors

Overexpression of the Phosphatidylinositol 3-kinase (PI3K) proteins have been observed in cancer cells. Targeting the phosphatidylinositol 3-kinase (PI3K) signaling transduction pathway by inhibition of the PI3K substrate recognition sites has been proved to be an effective approach to block cancer progression. Many PI3K inhibitors have been developed. Seven drugs have been approved by the US FDA with a mechanism of targeting the phosphatidylinositol 3-kinase/protein kinase-B/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway. In this study, we used docking tools to investigate selective binding of ligands toward four different subtypes of PI3Ks (PI3Kα, PI3Kβ, PI3Kγ and PI3Kδ). The affinity predicted from both the Glide dock and the Movable-Type (MT)-based free energy calculations agreed well with the experimental data. The validation of our predicted methods with a large dataset of 147 ligands showed very small mean errors. We identified residues that may dictate the subtype-specific binding. Particularly, residues Asp964, Ser806, Lys890 and Thr886 of PI3Kγ might be utilized for PI3Kγ-selective inhibitor design. Residues Val828, Trp760, Glu826 and Tyr813 may be important for PI3Kδ-selective inhibitor binding.

Scrambled eggs-Negative impacts of heat stress and chemical exposures on ovarian function in swine.

Exposure to environmental toxicants and hyperthermia can hamper reproduction in female mammals including swine. Phenotypic manifestations include poor quality oocytes, endocrine disruption, infertility, lengthened time to conceive, pregnancy loss, and embryonic defects. The ovary has the capacity for toxicant biotransformation, regulated in part by the phosphatidylinositol-3 kinase signaling pathway. The impacts of exposure to mycotoxins and pesticides on swine reproduction and the potential for an emerging chemical class of concern, the per- and polyfluoroalkylated substances, to hamper porcine reproduction are reviewed. The negative impairments of heat stress (HS) on swine reproductive outcomes are also described and the cumulative effect of environmental exposures, such as HS, when present in conjunction with a toxicant is considered.