Phosphatidylinositol 3-kinase Pathway Research Articles

Abstract C045: Combinations of PI3K inhibitors with targeted oncology agents in multicellular spheroid models

Abstract Dysregulation of the phosphatidylinositol 3-kinase (PI3K) pathway plays a significant role in cancer, and inhibitors offer a promising strategy for targeted therapies. The selectivity of current inhibitors varies against different PI3K isoforms or subtypes. For example, alpelisib and inavolisib predominantly target the α-isoform, whereas duvelisib targets the δ- and γ-isoforms. By contrast, copanlisib is a pan-PI3K inhibitor, exhibiting activity against all isoforms. In combinations with other targeted agents, we investigated the activity of these four PI3K inhibitors against multicellular spheroids. The multicellular spheroids, grown from 60% malignant cells, 25% endothelial cells, and 15% mesenchymal stem cells, served as a model for human solid tumors that incorporates both malignant and stromal components. Thirty multicellular spheroid models were grown from various malignant cell types, including twenty-seven patient-derived cancer cell lines obtained from the NCI Patient-Derived Models Repository (https://pdmr.cancer.gov/) and three established cell lines from the NCI-60 human tumor cell line panel. After three days of spheroid growth, anticancer agents were introduced at concentrations up to their reported clinical Cmax value, if known. After seven days of drug exposure, cell viability was measured using the CellTiter-Glo 3D assay. Among the various drug combinations evaluated, simultaneous targeting of the PI3K and RAS pathways was highly effective, particularly against malignant cell lines with an activated RAS pathway. Notably, additive and/or synergistic activities were observed when either the α-isoform-specific PI3K inhibitors (alpelisib and inavolisib) or the pan-PI3K inhibitor (copanlisib) was combined with either the MEK inhibitor selumetinib, the ERK inhibitor ravoxertinib, or the type II pan-RAF kinase inhibitor DAY101. Additionally, combinations of the same three PI3K inhibitors with variant-specific inhibitors, such as vemurafenib (BRAF V600E), sotorasib (KRAS G12C), or MTRX-1133 (KRAS G12D) demonstrated selective activity against cell lines carrying the variant. Another effective combination with PI3K inhibitors was achieved with vertical inhibition of the PI3K pathway through the addition of the mTORC1/2 kinase inhibitor sapanisertib. Finally, combinations of a CDK4/6 inhibitor (abemaciclib or palbociclib) with a PI3K inhibitor demonstrated synergistic activities, although they were not as potent as other combinations. This project was funded in part with federal funds from the NCI, NIH, under contract no. HHSN261201500003I. Citation Format: Thomas S Dexheimer, Thomas Silvers, Nathan P Coussens, Rabih Said, Beverly A Teicher, James H Doroshow. Combinations of PI3K inhibitors with targeted oncology agents in multicellular spheroid models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C045.

MTORC1 Inhibitor Rapamycin Inhibits Growth of Cerebral Cavernous Malformation in Adult Mice.

Cerebral cavernous malformations (CCMs) are vascular malformations that frequently cause stroke. CCMs arise due to loss of function in one of the genes that encode the CCM complex, a negative regulator of MEKK3-KLF2/4 signaling in vascular endothelial cells. Gain-of-function mutations in PIK3CA (encoding the enzymatic subunit of the PI3K (phosphoinositide 3-kinase) pathway associated with cell growth) synergize with CCM gene loss-of-function to generate rapidly growing lesions. We recently developed a model of CCM formation that closely reproduces key events in human CCM formation through inducible CCM loss-of-function and PIK3CA gain-of-function in mature mice. In the present study, we use this model to test the ability of rapamycin, a clinically approved inhibitor of the PI3K effector mTORC1, to treat rapidly growing CCMs. We show that both intraperitoneal and oral administration of rapamycin arrests CCM growth, reduces perilesional iron deposition, and improves vascular perfusion within CCMs. Our findings further establish this adult CCM model as a valuable preclinical model and support clinical testing of rapamycin to treat rapidly growing human CCMs.

Ran-Binding Protein 3 Phosphorylation Links the Ras and PI3-Kinase Pathways to Nucleocytoplasmic Transport

Ran-Binding Protein 3 Phosphorylation Links the Ras and PI3-Kinase Pathways to Nucleocytoplasmic Transport

TAS0612, a Novel RSK, AKT, and S6K Inhibitor, Exhibits Antitumor Effects in Preclinical Tumor Models.

The MAPK and PI3K pathways are involved in cancer growth and survival; however, the clinical efficacy of single inhibitors of each pathway is limited or transient owing to resistance mechanisms, such as feedback signaling and/or reexpression of receptor-type tyrosine kinases (RTK). This study identified a potent and novel kinase inhibitor, TAS0612, and characterized its properties. We found that TAS0612 is a potent, orally available compound that can inhibit p90RSK (RSK), AKT, and p70S6K (S6K) as a single agent and showed a strong correlation with the growth inhibition of cancer cells with PTEN loss or mutations, regardless of the presence of KRAS and BRAF mutations. Additional RSK inhibitory activity may differentiate the sensitivity profile of TAS0612 from that of signaling inhibitors that target only the PI3K pathway. Moreover, TAS0612 demonstrated broad-spectrum activity against tumor models wherein inhibition of MAPK or PI3K pathways was insufficient to exert antitumor effects. TAS0612 exhibited a stronger growth-inhibitory activity against the cancer cell lines and tumor models with dysregulated signaling with the genetic abnormalities described above than treatment with inhibitors against AKT, PI3K, MEK, BRAF, and EGFR/HER2. In addition, TAS0612 demonstrated the persistence of blockade of downstream growth and antiapoptotic signals, despite activation of upstream effectors in the signaling pathway and FoxO-dependent reexpression of HER3. In conclusion, TAS0612 with RSK/AKT/S6K inhibitory activity may provide a novel therapeutic strategy for patients with cancer to improve clinical responses and overcome resistance mechanisms.

An Updated Review on KRAS Mutation in Lung Cancer (NSCLC) and Its Effects on Human Health.

The largest cause of cancer-related fatalities worldwide is lung cancer. In its early stages, lung cancer often exhibits no signs or symptoms. Its signs and symptoms often appear when the condition is advanced. The Kirsten rat sarcoma virus oncogene homolog is one of the most frequently mutated oncogenes found in non-small cell lung cancer. Patients who have these mutations may do worse than those who do not, in terms of survival. To understand the nuances in order to choose the best treatment options for each patient, including combination therapy and potential resistance mechanisms, given the quick development of pharmaceuticals, it is necessary to know the factors that might contribute to this disease. It has been observed that single nucleotide polymorphisms altering let-7 micro-RNA might impact cancer propensity. On the other hand, gefitinib fails to stop the oncogenic protein from directly interacting with phosphoinositide3-kinase, which may explain its resistance towards cancer cells. Additionally, Atorvastatin may be able to overpower gefitinib resistance in these cancer cells that have this mutation regardless of the presence of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha. De novo lipogenesis is also regulated by this virus. To overcome these effects, several targeted therapies have been proposed. One such therapy is to use inhibitors of focal adhesion kinases. When this is inhibited, viral oncogene mutant cancers are effectively stopped because it functions downstream of the virus. Mutant oncoproteins like epidermal growth factor receptor may depend on Heat Shock protein90 chaperones more frequently than they do on natural counterparts that make it more attractive therapeutic target for this virus. Inhibition of the phosphoinositide 3-kinase pathway is frequent in lung cancer, and fabrication of inhibitors against this pathway can also be an effective therapeutic strategy. Blocking programmed cell death ligand1 is another therapy that may help T cells to recognize and eliminate cancerous cells. This homolog is a challenging therapeutic target due to its complex structural makeup and myriad biological characteristics. Thanks to the unrelenting efforts of medical research, with the use of some inhibitors, immunotherapy, and other combination methods, this problem is currently expected to be overcome.

Duvelisib for Critically Ill Patients With Coronavirus Disease 2019: An Investigator-Initiated, Randomized, Placebo-Controlled, Double-Blind Pilot Trial.

Despite improvements in prevention and treatment, severe coronavirus disease 2019 (COVID-19) is associated with high mortality. Phosphoinositide 3-kinase (PI3K) pathways contribute to cytokine and cell-mediated lung inflammation. We conducted a randomized, placebo-controlled, double-blind pilot trial to determine the feasibility, safety, and preliminary activity of duvelisib, a PI3Kδγ inhibitor, for the treatment of COVID-19 critical illness. We enrolled adults aged ≥18 years with a primary diagnosis of COVID-19 with hypoxic respiratory failure, shock, and/or new cardiac disease, without improvement after at least 48 hours of corticosteroid. Participants received duvelisib (25 mg) or placebo for up to 10 days. Participants had daily semi-quantitative viral load measurements performed. Dose modifications were protocol driven due to adverse events (AEs) or logarithmic change in viral load. The primary endpoint was 28-day overall survival (OS). Secondary endpoints included hospital and intensive care unit length of stay, 60-day OS, and duration of critical care interventions. Safety endpoints included viral kinetics and AEs. Exploratory endpoints included serial cytokine measurements and cytometric analysis. Fifteen patients were treated in the duvelisib cohort, and 13 in the placebo cohort. OS at 28 days was 67% (95% confidence interval [CI], 38%-88%) compared to 62% (95% CI, 32%-86%) for placebo (P = .544). Sixty-day OS was 60% versus 46%, respectively (hazard ratio, 0.66 [95% CI, .22-1.96]; P = .454). Other secondary outcomes were comparable. Duvelisib was associated with lower inflammatory cytokines. In this pilot study, duvelisib did not significantly improve 28-day OS compared to placebo for severe COVID-19. Duvelisib appeared safe in this critically ill population and was associated with reduction in cytokines implicated in COVID-19 and acute respiratory distress syndrome, supporting further investigation. NCT04372602.

FDA approved fused-pyrimidines as potential PI3K inhibitors: a computational repurposing approach

Fused pyrimidine scaffold is present in several US FDA-approved drugs for various therapeutic indications. Drug repurposing (or drug repositioning) involves the analysis of existing clinically approved drugs for new therapeutic indications. Phosphoinositide-3-kinase (PI3K), via the regulatory PI3K pathway, is involved in cell growth, proliferation, differentiation, survival, and angiogenesis. It is also considered a target in anticancer drug development as it promotes the growth of cancerous cells and increases resistance to anticancer therapy. The present work employed computational techniques like molecular docking, MMGBSA analysis, and molecular dynamics simulations to explore the PI3K inhibition by FDA-approved drugs with fused pyrimidine scaffold. The work identifies Lapatinib as a pan-class I PI3K inhibitor and Dipyridamole as an γ isoform-specific PI3K inhibitor and is reported here. Communicated by Ramaswamy H. Sarma

Interleukin-6 Inhibits Expression of miR-204-5p, a Regulator of Oligodendrocyte Differentiation: Involvement of miR-204-5p in the Prevention of Chemical-Induced Oligodendrocyte Impairment.

Oligodendrocytes (OLs) form myelin sheaths around axons in the central nervous system (CNS) facilitate the propagation of action potentials. The studies have shown that the differentiation and maturation of OLs involve microRNA (miR) regulation. The recent findings have addressed that miR-204 regulates OL differentiation in culture. In this study, through in situ hybridization in combination with immunohistochemistry, we showed that microRNA-204-5p in the corpus callosum was mainly expressed in OLs immunoreactive with adenomatous polyposis coli (APC), an OL marker. We also found miR-204-5p expression in mature OLs was suppressed by the addition of interleukin-6 (IL-6). Moreover, IL-6-induced inhibition of miR-204-5p expression was blocked by the addition of the inhibitors specific for p38 mitogen-activated protein kinase (p38MAPK) or phosphatidylinositol 3-kinase (PI3K) pathway. We further utilized a rat model by feeding cuprizone (CPZ)-containing diet for 3 weeks to induce demyelination and gliosis in the corpus callosum, as well as the upregulation of IL-6 gene expression significantly. Despite that miR-204-5p expression in the corpus callosum was not altered after feeding by CPZ for 3 weeks, its expression was increased and IL-6 transcription was decreased in the corpus callosum of the recovery group that was fed by CPZ for the first 2 weeks and by the regular diet for one more week. Our data demonstrate that miR-204-5p expression in OLs declined under the influence of the inflamed microenvironment. The findings that an increase in miR-204-5p and declined IL-6 expression observed in the recovery group might be involved with OL repair in the corpus callosum, and also shed light on a potential role for miR-204-5p in OL homeostasis following the white matter injury.

A new and powerful electrochemical sensing platform based on MWCNTs@Fe3O4@CuAl2O4 for the determination of the anticancer agent Alpelisib in bulk and biological fluids

Alpelisib, an anti-cancer drug with great potential, targets the phosphoinositide 3-kinase (PI3K) pathway, which is commonly dysregulated in various cancer types. Accurate and sensitive quantification of Alpelisib is crucial for optimizing treatment strategies and monitoring therapeutic outcomes. In this study, we have developed the first electrochemical sensor utilizing a modified electrode to precisely determine Alpelisib concentrations. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and Electrochemical impedance spectroscopy (EIS) techniques were extensively employed to investigate the electrochemical behavior of Alpelisib. The modified electrode was constructed by immobilizing multi-walled carbon nanotubes (MWCNTs), iron oxide (Fe3O4), and copper aluminum spinel (CuAl2O4) onto a glassy carbon electrode (GCE). This modification scheme aimed to improve the electrocatalytic activity and selectivity of the electrode towards Alpelisib. Subsequently, the developed electrode was successfully applied for the detection of Alpelisib in pharmaceutical formulations and biological fluids, thus demonstrating its applicability in real-world scenarios. The limit of detection (LOD) was determined to be 0.036 μM, affirming the sensor’s high sensitivity in detecting low concentrations of Alpelisib.

THU380 A Case Of Alpelisib Induced Diabetic Ketoacidosis (Dka) In A Patient With Type 2 Diabetes Mellitus And Rechallenge With SGLT2 Inhibitor

Abstract Disclosure: V. Sekar: None. S. Shaik: None. Introduction: Alpelisib is a α-selective phosphatidylinositol 3-kinase (PI3K) inhibitor recently used in treatment of advanced breast cancer. Hyperglycemia is an expected adverse effect with the use of PI3K inhibitors. We report a case of Alpelisib induced worsening hyperglycemia in a patient with type 2 diabetes mellitus who developed DKA while on Empagliflozin and was rechallenged with Dapagliflozin to achieve better glycemic control. Case Description: 60-year-old female with known history of type 2 diabetes mellitus was referred to Endocrinology prior to the start of PI3K inhibitor, Alpelisib for metastatic breast cancer. On initial visit her Hemoglobin A1C was 7.4 % and she was on Empagliflozin 25 mg daily, Sitagliptin 100 mg daily, Metformin XR 500 mg daily and Insulin Glargine 30 units daily. Three weeks after initiation of Alpelisib, patient reported uncontrolled fasting and post-prandial hyperglycemia, therefore her basal insulin was up-titrated and added on prandial insulin. Sitagliptin was discontinued. Two weeks later patient was admitted with Euglycemic diabetic ketoacidosis (DKA) which was treated with IV insulin and IV fluids. Empagliflozin was stopped and discharged on basal bolus regimen. In the next 6 weeks basal bolus regimen was significantly up-titrated and added on correctional insulin along with increasing Metformin XR to 500 mg twice a day due to poor glycemic control. During this time patient was cautiously restarted on Dapagliflozin 5 mg daily after discussing the better outcomes for Alpelisib induced hyperglycemia versus risk of DKA with reuse of SGLT2 inhibitors. Since being on Dapagliflozin her blood sugars were better controlled and the insulin requirements plateaued. Patient was closely monitored, and she didn’t develop further episode of DKA. Discussion: The PI3K pathway controls the effect of insulin intracellularly and its activation promotes tumor development, spread and failure to anticancer treatment. PI3K inhibitor blocks the intracellular action of insulin which causes reversible insulin resistance and hyperglycemia which is the major side effect of this drug. Use of insulin to treat hyperglycemia was shown to partially reactivate the PI3K pathway in tumoral cells, leading to cellular proliferation. Therefore, insulin should be kept as the last line antihyperglycemic agent. Exploratory analysis of SOLAR-1* trial has shown better glycemic control with use of SGLT2 inhibitors in patient with Alpelisib induced hyperglycemia along with improved efficacy of Alpelisib against tumor growth. Both PI3K inhibitor and SGLT2 inhibitor has risk of causing DKA, but close monitoring and patient education helps to reduce the risk. Reference *Study Assessing the Efficacy and Safety of Alpelisib Plus Fulvestrant in Men and Postmenopausal Women with Advanced Breast Cancer Which Progressed on or After Aromatase Inhibitor Treatment Presentation: Thursday, June 15, 2023

Parkin regulates IGF2BP3 through ubiquitination in the tumourigenesis of cervical cancer.

Insulin-like growth Factor 2 mRNA-binding protein 3 (IGF2BP3) is a highly conserved RNA-binding protein and plays a critical role in regulating posttranscriptional modifications. Immunoprecipitation was used to examine the interaction of Parkin and IGF2BP3. Mass spectrometry was performed to identify the ubiquitination sites of IGF2BP3. RNA-immunoprecipitation was conducted to examine the target genes of IGF2BP3. Xenograft mouse model was constructed to determine the tumorigenesis of IGF2BP3. IGF2BP3 expression is negatively correlated with Parkin expression in human cervical cancer cells and tissues. Parkin directly interacts with IGF2BP3, and overexpression of Parkin causes the proteasomal degradation of IGF2BP3, while knockdown of PARK2 increases the protein levels of IGF2BP3. Mechanistically, in vivo and in vitro ubiquitination assays demonstrated that Parkin is able to ubiquitinate IGF2BP3. Moreover, the ubiquitination site of IGF2BP3 was identified at K213 in the first KH domain of IGF2BP3. IGF2BP3 mutation results in the loss of its oncogenic function as an m6A reader, resulting in the inactivation of the phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) signalling pathways. In addition, IGF2BP3 mutation results in the attenuation of Parkin-mediated mitophagy, indicating its inverse role in regulating Parkin. Consequently, the tumourigenesis of cervical cancer is also inhibited by IGF2BP3 mutation. IGF2BP3 is ubiquitinated and regulated by the E3 ubiquitin ligase Parkin in human cervical cancer and ubiquitination modification plays an important role in modulating IGF2BP3 function. Thus, understanding the role of IGF2BP3 in tumourigenesis could provide new insights into cervical cancer therapy.

Combination of sacubitril/valsartan and blockade of the PI3K pathway enhanced kidney protection in a mouse model of cardiorenal syndrome.

Angiotensin receptor-neprilysin inhibitor (ARNI) is an established treatment for heart failure. However, whether ARNI has renoprotective effects beyond renin-angiotensin system inhibitors alone in cardiorenal syndrome (CRS) has not been fully elucidated. Here, we examined the effects of ARNI on the heart and kidneys of CRS model mice with overt albuminuria and identified the mechanisms underlying ARNI-induced kidney protection. C57BL6 mice were subjected to chronic angiotensin II infusion, nephrectomy, and salt loading (ANS); they developed CRS phenotypes and were divided into the vehicle treatment (ANS-vehicle), sacubitril/valsartan treatment (ANS-ARNI), and two different doses of valsartan treatment (ANS-VAL M, ANS-VAL H) groups. Four weeks after treatment, the hearts and kidneys of each group were evaluated. The ANS-vehicle group showed cardiac fibrosis, cardiac dysfunction, overt albuminuria, and kidney fibrosis. The ANS-ARNI group showed a reduction in cardiac fibrosis and cardiac dysfunction compared with the valsartan treatment groups. However, regarding the renoprotective effects characterized by albuminuria and fibrosis, ARNI was less effective than valsartan. Kidney transcriptomic analysis showed that the ANS-ARNI group exhibited a significant enhancement in the phosphoinositide 3-kinase (PI3K)-AKT signalling pathway compared with the ANS-VAL M group. Adding PI3K inhibitor treatment to ARNI ameliorated kidney injury to levels comparable with those of ANS-VAL M while preserving the superior cardioprotective effect of ARNI. PI3K pathway activation has been identified as a key mechanism affecting remnant kidney injury under ARNI treatment in CRS pathology, and blockading the PI3K pathway with simultaneous ARNI treatment is a potential therapeutic strategy for treating CRS with overt albuminuria.

Anticancer Effects of Hesperidin on Gastric Cancer Cell Lines and Fibroblast Cell Lines by Reducing the Activation of PI3K Pathway

Background: Cancer is one of the leading causes of death worldwide. In recent years, the need to pay attention to medicinal plants has increased due to the side effects of drugs and drug treatment. Hesperidin has medicinal uses in traditional medicine and is used as an antidote for therapeutic diseases. This study was conducted to investigate the toxicity effect of Hesperidin on gastric cancer cell lines (AGS) and normal fibroblast cell lines (SKM). Methods: Hesperidin plant extract with different types (100, 50, 10, and 50 μg/mL) was released on AGS and SKM cell lines for 24 hours by MTT test. The amount of apoptosis induction was evaluated by flow cytometry with Annexin V/PI staining and changes in the expression of genes (BAX and BCL-2) by real-time polymerase chain reaction. The effect of the drug on phosphoinositide 3-kinases (PI3K) was determined by the Western blot technique. The data were analyzed by SPSS statistical software using a one-way variance test and Tukey’s test (P<005). Results: Hesperidin had a cytotoxic effect on SKM and AGS cell lines and induced apoptosis. In the treatment with Hesperidin (100 μg/mL) for 24 hours, gene expression decreased in AGS and SKM and increased in BCL2 and BAX, (P<005). The growth rate of PI3K was decreased by the effect of the drug. Conclusion: Hesperidin, with a specific effect on SKM and AGS cancer cells, has the ability to grow these cells at a dose of 100 micrograms per milliliter.

PI3Kδ Pathway Dysregulation and Unique Features of Its Inhibition by Leniolisib in Activated PI3Kδ Syndrome and Beyond

The phosphoinositide 3-kinase (PI3K) pathway regulates diverse cellular processes, with finely tuned PI3Kδ activity being crucial for immune cell development and function. Genetic hyperactivation of PI3Kδ causes the inborn error of immunity activated phosphoinositide 3-kinase δ syndrome (APDS). Several PI3Kδ inhibitors have been investigated as treatment options for APDS, but only leniolisib has shown both efficacy and tolerability. In contrast, severe immune-mediated adverse events such as colitis, neutropenia, and hepatotoxicity have been observed with other PI3Kδ inhibitors, particularly those indicated for hematological malignancies. We propose that leniolisib is distinguished from other PI3Kδ inhibitors due to its structure, specific inhibitory properties selectively targeting the δ isoform without overinhibition of the δ or γ isoforms, and the precise match between APDS mechanism of disease and drug mechanism of action.

Toxic manifestations of alpelisib in endocrinology. Description of the clinical case

Breast cancer (BC) is a serious disease and is considered an important health problem worldwide. The prevalence of the disease in women according to Rosstat was 64,951 cases in the Russian Federation in 2020 (21.7% among all types of cancer). Hormone-dependent estrogen receptor-positive (HR+), human epidermal growth factor receptor type 2 negative (HER2-) metastatic breast cancer (mBC) accounts for 70% of all cases. About 40% of patients with ER+/HER2- mBC have mutations in the PIK3CA gene, leading to hyperactivation of the alpha isoform (p110α) of phosphatidylinositol 3-kinase (PI3K). Hormonal therapy with or without cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor is considered the standard treatment for patients with ER+/HER2- mBC. However, acquired resistance to this therapy remains a problem. Innovative methods for the treatment of breast cancer are the use of targeted therapeutic agents aimed at direct inhibition of the PI3K pathway in combination with hormone therapy. Alpelisib is a PI3Kα-specific inhibitor. Hyperglycemia is the most common side effect of alpelisib treatment. Currently, there is a consensus on the prevention and correction of hyperglycemia in patients receiving therapy with alpelisib, which recommends that before starting therapy, in order to diagnose carbohydrate metabolism disorders and assess the risk of developing hyperglycemia, determine in all patients: the level of glycated hemoglobin (HbA1c), glucose fasting plasma (FPG), body mass index (BMI). And also to evaluate such risk factors as the presence of a family history of type 2 diabetes mellitus (DM 2), the presence of gestational diabetes in the patient's history, or the fact of the birth of children weighing more than 4 kilograms.Recently, new combinations of drugs have been actively used to treat disorders of carbohydrate metabolism, such as pioglitazone + metformin. This paper discusses the mechanism of action of PI3K inhibitors, new therapeutic combinations and their undesirable effects, and presents therapeutic experience.

Dendritogenic Potential of the Ethanol Extract from Lippia alba Leaves in Rat Cortical Neurons.

A reduced dendritic complexity, especially in regions such as the hippocampus and the prefrontal cortex, has been linked to the pathophysiology of some neuropsychiatric disorders, in which synaptic plasticity and functions such as emotional and cognitive processing are compromised. For this reason, the identification of new therapeutic strategies would be enriched by the search for metabolites that promote structural plasticity. The present study evaluated the dendritogenic potential of the ethanol extract of Lippia alba, an aromatic plant rich in flavonoids and terpenes, which has been widely used in traditional medicine for its presumed analgesic, anxiolytic, and antidepressant potential. An in vitro model of rat cortical neurons was used to determine the kinetics of the plant's effect at different time intervals. Changes in morphological parameters of the neurons were determined, as well as the dendritic complexity, by Sholl analysis. The extract promotes the outgrowth of dendritic branching in a rapid and sustained fashion, without being cytotoxic to the cells. We found that this effect could be mediated by the phosphatidylinositol 3-kinase pathway, which is involved in mechanisms of neuronal plasticity, differentiation, and survival. The evidence presented in this study provides a basis for further research that, through in vivo models, can delve into the plant's therapeutic potential.

Therapeutic Peptide RF16 Derived from CXCL8 Inhibits MDA-MB-231 Cell Invasion and Metastasis.

Interleukin (IL)-8 plays a vital role in regulating inflammation and breast cancer formation by activating CXCR1/2. We previously designed an antagonist peptide, (RF16), to inhibits the activation of downstream signaling pathways by competing with IL-8 in binding to CXCR1/2, thereby inhibiting IL-8-induced chemoattractant monocyte binding. To evaluate the effect of the RF16 peptide on breast cancer progression, triple-negative MDA-MB-231 and ER-positive MCF-7 breast cancer cells were used to investigate whether RF16 can inhibit the IL-8-induced breast cancer metastasis. Using growth, proliferation, and invasiveness assays, the results revealed that RF16 reduced cell proliferation, migration, and invasiveness in MDA-MB-231 cells. The RF16 peptide also regulated the protein and mRNA expressions of epithelial-mesenchymal transition (EMT) markers in IL-8-stimulated MDA-MB-231 cells. It also inhibited downstream IL-8 signaling and the IL-8-induced inflammatory response via the mitogen-activated protein kinase (MAPK) and Phosphoinositide 3-kinase (PI3K) pathways. In the xenograft tumor mouse model, RF16 synergistically reinforces the antitumor efficacy of docetaxel by improving mouse survival and retarding tumor growth. Our results indicate that RF16 significantly inhibited IL-8-stimulated cell growth, migration, and invasion in MDA-MB-231 breast cancer cells by blocking the activation of p38 and AKT cascades. It indicated that the RF16 peptide may serve as a new supplementary drug for breast cancer.

Sodium-glucose cotransporter-2 inhibitors for hypergycemia in phosphoinositide 3-kinase pathway inhibition.

Phosphoinositide 3-kinase (PI3K) inhibition is used for the treatment of certain cancers, but can cause profound hyperglycemia and insulin resistance, for which sodium-glucose cotransporter-2 (SGLT2) inhibitors have been proposed as a preferred therapy. The objective of this research is to assess the effectiveness and safety of SGLT2 inhibitors for hyperglycemia in PI3K inhibition. We conducted a single-center retrospective review of adults initiating the PI3K inhibitor alpelisib. Exposure to different antidiabetic drugs and adverse events including diabetic ketoacidosis (DKA) were assessed through chart review. Plasma and point-of-care blood glucoses were extracted from the electronic medical record. Change in serum glucose and the rate of DKA on SGLT2 inhibitor versus other antidiabetic drugs were examined as co-primary outcomes. We identified 103 patients meeting eligibility criteria with median follow-up of 92days after starting alpelisib. When SGLT2 inhibitors were used to treat hyperglycemia, they were associated with a decrease in mean random glucose by -46mg/dL (95% CI -77 to -15) in adjusted linear modeling. Five cases of DKA were identified, two occurring in patients on alpelisib plus SGLT2 inhibitor. Estimated incidence of DKA was: alpelisib plus SGLT2 inhibitor, 48 DKA cases per 100 patient-years (95% CI 6, 171); alpelisib with non-SGLT2 inhibitor antidiabetic drugs, 15 (95% CI 2, 53); alpelisib only, 4 (95% CI 0.1, 22). SGLT2 inhibitors are effective treatments for hyperglycemia in the setting of PI3K inhibition.

FBXO21 mediated degradation of p85α regulates proliferation and survival of acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease characterized by clonal expansion of myeloid blasts in the bone marrow (BM). Despite advances in therapy, the prognosis for AML patients remains poor, and there is a need to identify novel molecular pathways regulating tumor cell survival and proliferation. F-box ubiquitin E3 ligase, FBXO21, has low expression in AML, but expression correlates with survival in AML patients and patients with higher expression have poorer outcomes. Silencing FBXO21 in human-derived AML cell lines and primary patient samples leads to differentiation, inhibition of tumor progression, and sensitization to chemotherapy agents. Additionally, knockdown of FBXO21 leads to up-regulation of cytokine signaling pathways. Through a mass spectrometry-based proteomic analysis of FBXO21 in AML, we identified that FBXO21 ubiquitylates p85α, a regulatory subunit of the phosphoinositide 3-kinase (PI3K) pathway, for degradation resulting in decreased PI3K signaling, dimerization of free p85α and ERK activation. These findings reveal the ubiquitin E3 ligase, FBXO21, plays a critical role in regulating AML pathogenesis, specifically through alterations in PI3K via regulation of p85α protein stability.

P10.19.A COMBINED TREATMENT USING MAPK AND PI3K SIGNALING PATHWAYS INHIBITORS EFFECTIVELY REDUCES GROWTH OF MELANOMA BRAIN METASTASIS CELLS IN VITRO

Abstract BACKGROUND Brain metastasis is associated with poor prognosis, and median survival time from the time of diagnosis for cancer patients with brain metastases is only a few months. Brain metastases are estimated to occur in 20-40% of cancer patients. All solid tumors may spread to the brain, but the risk of developing brain metastases is higher in breast cancer, lung cancer and melanoma. Standard treatment of melanoma brain metastases (MBM) includes radiation therapy and surgery. In melanoma, the mitogen activated protein kinase (MAPK) and the phosphoinositide 3-kinase (PI3K) signaling pathways are often activated by genetic alterations. An activation mutation (BRAFV600E) in the MAPK pathway is commonly found in melanoma refractory to therapy. This mutation leads to increased proliferation and tumor cell survival. Previous studies show that BRAF-inhibitors block the increase in cell proliferation induced by the activated BRAF gene, however, many of the patients develop drug resistance within a few months. Objectives: In this project, we aimed to show that drugs targeting BRAF (vemurafenib) and PI3K pathways (buparlisib) used in combination effectively inhibit growth of treatment resistant MBM cells. MATERIAL AND METHODS Our research lab has previously developed human MBM cell lines, which have been made resistant towards vemurafenib treatment. To study the potential antitumoral effects of combined treatment we used these cells in several in vitro assays such as cell viability and proliferation, cell migration, colony forming assay, spheroid growth, apoptosis by IncuCyte and western blot to confirm effects on signaling pathways. RESULTS We found that combination treatment reduced the viability of resistant MBM cells, as well as their ability to proliferate. Further, the cells showed less ability to migrate after therapy. Altered cell morphology was also seen. Initial results show effects on colony formation and increased apoptosis after combined treatment. CONCLUSION A combination of MAPK and PI3K inhibitors effectively inhibits growth and viability of treatment resistant human MBM cells, compared to single drug treatment alone. The results support clinical use of combined therapy for melanoma patients with metastatic disease.