Alpha Isoforms Research Articles

Inavolisib-Based Therapy in PIK3CA-Mutated Advanced Breast Cancer

BackgroundInavolisib is a highly potent and selective inhibitor of the alpha isoform of the p110 catalytic subunit of the phosphatidylinositol 3-kinase complex (encoded by PIK3CA) that also promotes the degradation of mutated p110α. Inavolisib plus palbociclib–fulvestrant has shown synergistic activity in preclinical models and promising antitumor activity in early-phase trials.MethodsIn a phase 3, double-blind, randomized trial, we compared first-line inavolisib (at an oral dose of 9 mg once daily) plus palbociclib–fulvestrant (inavolisib group) with placebo plus palbociclib–fulvestrant (placebo group) in patients with PIK3CA-mutated, hormone receptor–positive, human epidermal growth factor receptor 2 (HER2)–negative locally advanced or metastatic breast cancer who had had relapse during or within 12 months after the completion of adjuvant endocrine therapy. The primary end point was progression-free survival as assessed by the investigator.ResultsA total of 161 patients were assigned to the inavolisib group and 164 to the placebo group; the median follow-up was 21.3 months and 21.5 months, respectively. The median progression-free survival was 15.0 months (95% confidence interval [CI], 11.3 to 20.5) in the inavolisib group and 7.3 months (95% CI, 5.6 to 9.3) in the placebo group (hazard ratio for disease progression or death, 0.43; 95% CI, 0.32 to 0.59; P<0.001). An objective response occurred in 58.4% of the patients in the inavolisib group and in 25.0% of those in the placebo group. The incidence of grade 3 or 4 neutropenia was 80.2% in the inavolisib group and 78.4% in the placebo group; grade 3 or 4 hyperglycemia, 5.6% and 0%, respectively; grade 3 or 4 stomatitis or mucosal inflammation, 5.6% and 0%; and grade 3 or 4 diarrhea, 3.7% and 0%. No grade 3 or 4 rash was observed. Discontinuation of any trial agent because of adverse events occurred in 6.8% of the patients in the inavolisib group and in 0.6% of those in the placebo group.ConclusionsIn patients with PIK3CA-mutated, hormone receptor–positive, HER2-negative locally advanced or metastatic breast cancer, inavolisib plus palbociclib–fulvestrant led to significantly longer progression-free survival than placebo plus palbociclib–fulvestrant, with a greater incidence of toxic effects. The percentage of patients who discontinued any trial agent because of adverse events was low. (Funded by F. Hoffmann–La Roche; INAVO120 ClinicalTrials.gov number, NCT04191499.)

8795 Impact of Retinoic Acid Receptor Alpha Conditional Knockout on Ovarian Follicle Development in the Mouse

Abstract Disclosure: Z. Bogin: None. A. Keisker: None. A. Urbanowski: None. C. White: None. J.L. Kipp: None. The ovaries are the primary endocrine and reproductive organs in females. The ovarian follicle is the basic structural and functional unit of the ovary. When there is abnormal development in ovarian follicles, infertility and reproductive diseases such as polycystic ovarian syndrome (PCOS), premature ovarian failure (POF), and ovarian cancers may occur. Retinoic acid (RA), a biologically active derivative of vitamin A, is a signaling molecule that plays a vital role in various physiological processes, including embryonic development, tissue differentiation, and reproduction. We have shown that RA stimulates granulosa cell proliferation through a cell signaling cascade involving Retinoic Acid Receptors (RARs), which have three isoforms alpha, beta, and gamma. In this study, we characterized a new retinoic acid receptor alpha conditional knockout (RARA cKO) mouse model with RARA deleted in granulosa cells during embryonic development. The body weight and uterus weight of the RARA cKO mice were decreased at week 7 but returned to normal at week 15 and 12 months. The animals were either sub-fertile or infertile with phenotypic evidence of POF. In addition, a variety of ovarian pathologies were observed, including the presence of hemosiderin, increased cyst formation, and abnormal follicle counts. Overall, this study provides evidence of the involvement of retinoic acid signaling, mediated by RARA, in ovarian development and fertility. This study will help to better understand the prevention and treatment of ovarian diseases. Presentation: 6/2/2024

8795 Impact of Retinoic Acid Receptor Alpha Conditional Knockout on Ovarian Follicle Development in the Mouse

Abstract Disclosure: Z. Bogin: None. A. Keisker: None. A. Urbanowski: None. C. White: None. J.L. Kipp: None. The ovaries are the primary endocrine and reproductive organs in females. The ovarian follicle is the basic structural and functional unit of the ovary. When there is abnormal development in ovarian follicles, infertility and reproductive diseases such as polycystic ovarian syndrome (PCOS), premature ovarian failure (POF), and ovarian cancers may occur. Retinoic acid (RA), a biologically active derivative of vitamin A, is a signaling molecule that plays a vital role in various physiological processes, including embryonic development, tissue differentiation, and reproduction. We have shown that RA stimulates granulosa cell proliferation through a cell signaling cascade involving Retinoic Acid Receptors (RARs), which have three isoforms alpha, beta, and gamma. In this study, we characterized a new retinoic acid receptor alpha conditional knockout (RARA cKO) mouse model with RARA deleted in granulosa cells during embryonic development. The body weight and uterus weight of the RARA cKO mice were decreased at week 7 but returned to normal at week 15 and 12 months. The animals were either sub-fertile or infertile with phenotypic evidence of POF. In addition, a variety of ovarian pathologies were observed, including the presence of hemosiderin, increased cyst formation, and abnormal follicle counts. Overall, this study provides evidence of the involvement of retinoic acid signaling, mediated by RARA, in ovarian development and fertility. This study will help to better understand the prevention and treatment of ovarian diseases. Presentation: 6/2/2024

Suppressed ORAI1-STIM1-dependent Ca2+ entry by protein kinase C isoforms regulating platelet procoagulant activity

Agonist-induced rises in cytosolic Ca2+ control most platelet responses in thrombosis and hemostasis. In human platelets we earlier demonstrated that the ORAI1-STIM1 pathway is a major component of extracellular Ca2+ entry, in particular when induced via the ITAM-linked collagen receptor, glycoprotein VI (GPVI). In the present paper, using functionally defective platelets from patients with a loss-of-function mutation in ORAI1 or STIM1, we show that Ca2+ entry induced by the endoplasmic reticulum ATPase inhibitor, thapsigargin, fully relies on this pathway. We demonstrate that both the GPVI-induced and thapsigargin-induced Ca2+ entry is strongly suppressed by protein kinase C (PKC) activation, while leaving intracellular Ca2+ mobilization unchanged. Comparing effects of a PKC inhibitory panel pointed to redundant roles of beta and theta PKC isoforms in Ca2+-entry suppression. In contrast, tyrosine kinases positively regulated GPVI-induced Ca2+ entry and mobilization. Label-free and stable isotope phosphoproteome analysis of GPVI-stimulated platelets suggested a regulatory role of bridging integrator-2 (BIN2), known as important mediator of the ORAI1-STIM1 pathway in mouse platelets. Identified were 25-45 regulated phospho- sites in BIN2 and 16-18 in STIM1. Five of these were characterized as direct substrates of the expressed PKC isoforms alpha, beta delta and theta. Functional platelet testing indicated that the downregulation of Ca2+ entry by PKC resulted in suppressed phosphatidylserine exposure and plasmatic thrombin generation. Conclusively, our results indicate that in platelets multiple PKC isoforms constrain the store-regulated Ca2+ entry via ORAI1-BIN2-STIM1, and hence downregulate platelet-dependent coagulation.

PP2A catalytic subunit alpha is critically required for CD8+ T-cell homeostasis and antibacterial responses.

Although the functions of tyrosine phosphatases in T-cell biology have been extensively studied, our knowledge on the contribution of serine/threonine phosphatases in T cells remains poor. Protein phosphatase 2A (PP2A) is one of the most abundantly expressed serine/threonine phosphatases. It is important in thymocyte development and CD4+ T-cell differentiation. Utilizing a genetic model in which its catalytic subunit alpha isoform (PP2A Cα) is deleted in T cells, we investigated its contribution to CD8+ T-cell homeostasis and effector functions. Our results demonstrate that T-cell intrinsic PP2A Cαis critically required for CD8+ T-cell homeostasis in secondary lymphoid organs and intestinal mucosal site. Importantly, PP2A Cα-deficient CD8+ T cells exhibit reduced proliferation and survival. CD8+ T-cell antibacterial response is strictly dependent on PP2A Cα.Expression of Bcl2 transgene rescues CD8+ T-cell homeostasis in spleens, but not in intestinal mucosal site, nor does it restore defective antibacterial responses. Finally, proteomics and phosphoproteomics analyses reveal potential targets dependent on PP2A Cα,including mTORC1 and AKT.Thus, PP2A Cα is a key modulator of CD8+ T-cell homeostasis and effector functions.

Generic semi-automated radiofluorination strategy for single domain antibodies: [18F]FB-labelled single domain antibodies for PET imaging of fibroblast activation protein-α or folate receptor-α overexpression in cancer

BackgroundRadiofluorination of single domain antibodies (sdAbs) via N-succinimidyl-4-[18F]fluorobenzoate ([18F]SFB) has shown to be a promising strategy in the development of sdAb-based PET tracers. While automation of the prosthetic group (PG) [18F]SFB production, has been successfully reported, no practical method for large scale sdAb labelling has been reported. Therefore, we optimized and automated the PG production, enabling a subsequently efficient manual conjugation reaction to an anti-fibroblast activation protein (FAP)-α sdAb (4AH29) and an anti-folate receptor (FR)-α sdAb (2BD42). Both the alpha isoform of FAP and the FR are established tumour markers. FAP-α is known to be overexpressed mainly by cancer-associated fibroblasts in breast, ovarian, and other cancers, while its expression in normal tissues is low or undetectable. FR-α has an elevated expression in epithelial cancers, such as ovarian, brain and lung cancers. Non-invasive imaging techniques, such as PET-imaging, using tracers targeting specific tumour markers can provide molecular information over both the tumour and its environment, which aides in the diagnosis, therapy selection and assessment of the cancer treatment.Results[18F]SFB was synthesized using a fully automated three-step, one-pot reaction. The total procedure time was 54 min and results in [18F]SFB with a RCP > 90% and a RCY d.c. of 44 ± 4% (n = 13). The manual conjugation reaction after purification produced [18F]FB-sdAbs with a RCP > 95%, an end of synthesis activity > 600 MBq and an apparent molar activity > 10 GBq/µmol. Overall RCY d.c., corrected to the trapping of [18F]F− on the QMA, were 9% (n = 1) and 5 ± 2% (n = 3) for [18F]FB-2BD42 and [18F]FB-4AH29, respectively.Conclusion[18F]SFB synthesis was successfully automated and upscaled on a Trasis AllInOne module. The anti-hFAP-α and anti-hFR-α sdAbs were radiofluorinated, yielding similar RCYs d.c. and RCPs, showing the potential of this method as a generic radiofluorination strategy for sdAbs. The radiofluorinated sdAbs showed a favourable biodistribution pattern and are attractive for further characterization as new PET tracers for FAP-α and FR-α imaging.

Canonical and Noncanonical Contribution of Thyroid Hormone Receptor Isoforms Alpha and Beta to Cardiac Hypertrophy and Heart Rate in Male Mice.

Background: Stimulation of ventricular hypertrophy and heart rate are two major cardiac effects of thyroid hormone (TH). The aim of this study was to determine invivo which TH receptor (TR)-α or β-and which mode of TR action-canonical gene expression or DNA-binding independent noncanonical action-mediate these effects. Methods: We compared global TRα and TRβ knockout mice (TRαKO; TRβKO) with wild-type (WT) mice to determine the TR isoform responsible for T3 effects. The relevance of TR DNA binding was studied in mice with a mutation in the DNA-binding domain that selectively abrogates DNA binding and canonical TR action (TRαGS; TRβGS). Hearts were studied with echocardiography at baseline and after 7 weeks of T3 treatment. Gene expression was measured with real-time polymerase chain reaction. Heart rate was recorded with radiotelemetry transmitters for 7 weeks in untreated, hypothyroid, and T3-treated mice. Results: T3 induced ventricular hypertrophy in WT and TRβKO mice, but not in TRαKO mice. Hypertrophy was also induced in TRαGS mice. Thus, hypertrophy is mostly mediated by noncanonical TRα action. Similarly, repression of Mhy7 occurred in WT and TRαGS mice. Basal heart rate was largely dependent on canonical TRα action. But responsiveness to hypothyroidism and T3 treatment as well as expression of pacemaker gene Hcn2 were still preserved in TRαKO mice, demonstrating that TRβ could compensate for absence of TRα. Conclusions: T3-induced cardiac hypertrophy could be attributed to noncanonical TRα action, whereas heart rate regulation was mediated by canonical TRα action. TRβ could substitute for canonical but not noncanonical TRα action.

Comprehensive analysis of resorcinyl-imidazole Hsp90 inhibitor design

Human Hsp90 chaperones are implicated in various aspects of cancer. Due to this, Hsp90 has been explored as potential target in cancer treatment. Initial attempts to use Hsp90 inhibitors in drug trials failed due to toxicity and inefficacy. The next generation of drugs were less toxic but still insufficiently effective in a clinical setting. Recently, a lot of effort is being put into understanding the consequences of Hsp90 isoform selective inhibition, expecting that this might hold the key in targeting Hsp90 for disease treatment. Here we investigate a series of compounds containing the aryl-resorcinol scaffold with a 5-membered ring as a promising class of new human Hsp90 inhibitors, reaching nanomolar affinity. We compare how the replacement of 5-membered ring, from thiadiazole to imidazole, as well as a variety of their substituents, influences the potency of these inhibitors for Hsp90 alpha and beta isoforms. To further elucidate the dissimilarity in ligand selectivity between the isoforms, a mutant protein was constructed and tested against the ligand library. In addition, we performed a series of molecular dynamics (MD) and docking simulations to further explain our experimental findings as well as evaluated key compounds in cell assays. Our results deepen the understanding of Hsp90 isoform ligand selectivity and serve as an informative base for further Hsp90 inhibitor optimization.

Tumor growth-arrest effect of tetrahydroquinazoline-derivative human topoisomerase II-alpha inhibitor in HPV-negative head and neck squamous cell carcinoma

Oral malignancies continue to have severe morbidity with less than 50% long-term survival despite the advancement in the available therapies. There is a persisting demand for new approaches to establish more efficient strategies for their treatment. In this regard, the human topoisomerase II (topoII) enzyme is a validated chemotherapeutics target, as topoII regulates vital cellular processes such as DNA replication, transcription, recombination, and chromosome segregation in cells. TopoII inhibitors are currently used to treat some neoplasms such as breast and small cells lung carcinomas. Additionally, topoII inhibitors are under investigation for the treatment of other cancer types, including oral cancer. Here, we report the therapeutic effect of a tetrahydroquinazoline derivative (named ARN21934) that preferentially inhibits the alpha isoform of human topoII. The treatment efficacy of ARN21934 has been evaluated in 2D cell cultures, 3D in vitro systems, and in chick chorioallantoic membrane cancer models. Overall, this work paves the way for further preclinical developments of ARN21934 and possibly other topoII alpha inhibitors of this promising chemical class as a new chemotherapeutic approach for the treatment of oral neoplasms.

Targeting Lewy body dementia with neflamapimod-rasagiline hybrids.

Lewy body dementia (LBD) represents the second most common neurodegenerative dementia but is a quite underexplored therapeutic area. Nepflamapimod (1) is a brain-penetrant selective inhibitor of the alpha isoform of the mitogen-activated serine/threonine protein kinase (MAPK) p38α, recently repurposed for LBD due to its remarkable antineuroinflammatory properties. Neuroprotective propargylamines are another class of molecules with a therapeutical potential against LBD. Herein, we sought to combine the antineuroinflammatory core of 1 and the neuroprotective propargylamine moiety into a single molecule. Particularly, we inserted a propargylamine moiety in position 4 of the 2,6-dichlorophenyl ring of 1, generating neflamapimod-propargylamine hybrids 3 and 4. These hybrids were evaluated using several cell models, aiming to recapitulate the complexity of LBD pathology through different molecular mechanisms. The N-methyl-N-propargyl derivative 4 showed a nanomolar p38α-MAPK inhibitory activity (IC50 = 98.7 nM), which is only 2.6-fold lower compared to that of the parent compound 1, while displaying no hepato- and neurotoxicity up to 25 μM concentration. It also retained a similar immunomodulatory profile against the N9 microglial cell line. Gratifyingly, at 5 μM concentration, 4 demonstrated a neuroprotective effect against dexamethasone-induced reactive oxygen species production in neuronal cells that was higher than that of 1.

Abstract A071: Identification and characterization of functionally distinct isoforms of estrogen receptor alpha in breast cancer

Abstract We used long- and short-read RNA sequencing of breast tumor tissue, breast cancer cell lines, and healthy tissues to create a comprehensive annotation of alternative mRNA isoforms of estrogen receptor alpha (ER, gene symbol ESR1) and combined this with functional studies of alternative protein isoforms. The ER is frequently overexpressed in breast cancer and is used in the clinic as a prognostic and treatment-predictive factor. It is also a drug target. The ER is a transcription factor and regulates gene expression in response to estrogen, a hormone that can stimulate breast cell proliferation and contribute to tumor growth. The gene has multiple promoters, and alternative mRNA isoforms have been linked to more aggressive breast tumors, suggesting that the splicing pattern of ER transcripts may influence breast cancer biology and clinical outcome. We cloned and characterized six alternative protein isoforms of ER. They were selected based on expression level in sequencing data, splice junction support, and only contained one alternative splicing event each compared to the full-length ER. Experimental characterization was done in cell lines and included transcription factor activity, alone and upon co-expression with full-length ER, response to the ER-targeting drugs tamoxifen and fulvestrant, as well as subcellular localization. Two alternative isoforms exhibited transcription factor activity, although at lower levels than the full-length ER, while isoforms with larger deletions in the DNA-binding domain or lacking parts of the ligand-binding domain were inactive. One isoform had a dominant negative effect on the activity of the full-length protein. Furthermore, full-length ER and three alternative isoforms were found in both cytoplasm and nucleus, while the remaining isoforms were only present in the cytoplasm. Isoforms capable of entering the nucleus showed increased nuclear localization upon estradiol treatment, with one isoform accumulating significantly higher and one lower than the full-length ER. Co-transfection of full-length ER and isoforms lacking transcription factor activity did not alter their distribution, suggesting a possible role of heterodimerization with full-length ER for the dominant negative isoform in the nucleus. In ongoing experiments, we are studying the regulation, expression, and function of alternative isoforms of ER in cell line models of drug resistance. These findings highlight the complexity and diversity of ER isoforms in breast cancer and suggest that specific isoforms may have distinct functional roles in tumor progression and response to therapy. Our work provides insights into the role of alternative mRNA splicing in breast cancer development and progression. Citation Format: Juliane Albrecht, Carlos Enrique Balcazar, Helena Persson, Völundur Hafstað, Cornelia Börjesson Freitag, Johan Vallon-Christersson, Jari Häkkinen. Identification and characterization of functionally distinct isoforms of estrogen receptor alpha in breast cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr A071.

Topical application of berberine ameliorates imiquimod-induced psoriasis-like dermatitis in BALB/c mice via suppressing JAK1/STAT1 signaling pathway

Psoriasis is a common chronic inflammatory skin disease, which has seriously affected human health. Berberine is a plant alkaloid with significant anti-inflammatory effect. In this study, we aimed to determine whether topical application of berberine could ameliorate skin inflammation in psoriasis and explore the potential molecular mechanism. Imiquimod (IMQ)-induced psoriasis-like dermatitis in mice was firstly used to reveal the potential pathogenic mechanism. The transcriptome analysis showed that Janus kinase (JAK)-Signal transducer and activator of transcription (STAT) signaling pathway was significantly enriched in IMQ-induced dermatitis, which included the key genes such as Janus kinase 1 (JAK1), Interleukin-2 (IL2), Phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha isoform (PIK3CA), Phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit beta isoform (PIK3CB) and Signal transducer and activator of transcription 1 (STAT1). Network pharmacology and molecular docking then predicted that topical berberine may treat psoriasis by JAK-STAT signaling pathway, especially act on JAK1, IL2, PIK3CA and PIK3CB. Experimental studies in vivo further demonstrated that topical application of berberine could ameliorate IMQ-induced psoriasis-like skin inflammation by suppressing JAK-STAT signaling pathway. In addition, experimental studies in vitro showed that berberine could directly act on and enter into human immortalized keratinocytes (HaCaT cells). Meanwhile, berberine may inhibit the hyperproliferation and proinflammatory functions of HaCaT cells induced by Interferon-gamma (IFN-γ) via suppressing JAK1/STAT1 signaling pathway. In conclusion, this study suggested that berberine may be a promising topical agent to ameliorate skin inflammation in psoriasis.

Abstract A029: Treatment-Specific Immune Phenotypes Identified by nELISA High-Throughput Proteomics Reveal Actionable Insights for Drug Discovery

Abstract Understanding tumor immunology requires high content tools that can capture the complex microenvironment, as well as high-throughput cell-based assays to rapidly screen compounds, antibodies, or cell therapies. Unfortunately, proteomics tools to investigate interactions between cancer and immune cells compromise either content or cost, limiting access to phenotypic data. To overcome this issue, we developed the nELISA: a high-throughput miniaturized ELISA quantifying 191 cytokines, chemokines, proteases and growth factors, at 10x-reduced cost compared to previous tools, and applied it to cell based models to demonstrate its ability to characterize immune phenotypes in co-culture systems. We ran the largest PBMC secretome screen to date, in which ~10,000 PBMC samples were treated with various inflammatory stimuli, and were further perturbed with a selected library of 80 recombinant protein “perturbagens”. 191 secreted proteins were profiled in all samples, resulting in ~2M datapoints. The nELISA profiles were able to capture phenotypes associated with specific stimulation conditions, individual donors, and potent cytokine perturbagens. By compensating for stimulation and donor differences, we clustered perturbagens according to their effects on PBMC secretomes. As expected, perturbagens such as IFN gamma and IL-4 led to well-established Th1 or Th2 responses, respectively, and clustered with perturbagens involved in these phenotypes. Novel phenotypic effects were also identified, such as distinct responses to the near identical CXCL12 alpha and beta isoforms. Interestingly, we observed important similarities between PBMC responses to the cytokine drugs IFN beta and IL-1 Receptor antagonist, supporting the use of the latter as a replacement for the former in certain indications. These findings highlight the ability of the nELISA to capture actionable insights from high-throughput screens, and demonstrate its applicability to SAR studies and drug repurposing screens. Thus, the nELISA is a powerful tool for immunotherapy drug discovery, and we will expand upon its use for target identification, in vitro pharmacology, predicting patient response to therapy, as well as characterizing the potential of iPSC- or donor-derived material for cell therapy. Citation Format: Nathaniel Robichaud, Grant Ongo, Ivan Teahulos, Woojong Rho, Milad Dagher. Treatment-Specific Immune Phenotypes Identified by nELISA High-Throughput Proteomics Reveal Actionable Insights for Drug Discovery [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A029.

Deciphering the chemical profile and pharmacological mechanism of Jinlingzi powder against bile reflux gastritis using ultra-high performance liquid chromatography coupled with Q exactive focus mass spectrometry, network pharmacology, and molecular docking.

To elucidate the chemical profile and the pharmacological mechanism by which Jinlingzi powder (, JLZP) treats bile reflux gastritis (BRG). A BRG model was established in rats by oral administration of the model solution. JLZP was orally administered for 35 d. Residual gastric rate and tumor necrosis factor (TNF)-α, interleukin (IL)-6, and gastrin levels in the serum were measured, and stomach tissues were collected for histopathological analysis. We used ultra-high performance liquid chromatography coupled with Q Exactive Focus mass spectrometry to identify the chemical ingredients in JLZP. Then, protein-protein interaction and herb-compound-target networks were constructed to screen potential bioactive compounds and targets. Kyoto Encyclopedia of Genes and Genomes pathway analysis was then performed to elucidate the pathway involved in the JLZP-mediated treatment of BRG. After constructing the core compound-target-pathway interaction network, molecular docking was performed to study the binding free energy of core bioactive compounds and two candidate targets [RAC-alpha serine/threonine-protein kinase (AKT1) and phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha isoform (PIK3CA)]. JLZP extracts significantly promoted gastric emptying, regulating the release of cytokines (TNF-α and IL-6) and improving gastrin secretion and mucosal repair. Fifty-six compounds were tentatively characterized in JLZP. Moreover, the network pharmacology and molecular docking results showed that alkaloids and flavonoids might be the bioactive compounds in JLZP that treat BRG. JLZP might improve mucosal repair during BRG progression by modulating the phosphatidylinositol-4,5-bisphosphate 3-kinase-protein kinase B, hypoxia inducible factor-1, mitogen-activated protein kinase, forkhead box O, TNF, and IL-17 signaling pathways. We elucidated the chemical constituents and the pharmacological mechanism of JLZP in treating BRG and provided a basis for clinical application.

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.

Alternative promoters and splicing create multiple functionally distinct isoforms of oestrogen receptor alpha in breast cancer and healthy tissues.

Oestrogen receptor alpha (ER) is involved in cell growth and proliferation and functions as a transcription factor, a transcriptional coregulator, and in cytoplasmic signalling. It affects, for example, bone, endometrium, ovaries and mammary epithelium. It is a key biomarker in clinical management of breast cancer, where it is used as a prognostic and treatment-predictive factor, and a therapeutical target. Several ER isoforms have been described, but transcript annotation in public databases is incomplete and inconsistent, and functional differences are not well understood. We have analysed short- and long-read RNA sequencing data from breast tumours, breast cancer cell lines, and normal tissues to create a comprehensive annotation of ER transcripts and combined it with experimental studies of full-length protein and six alternative isoforms. The isoforms have varying transcription factor activity, subcellular localisation, and response to the ER-targeting drugs tamoxifen and fulvestrant. Antibodies differ in ability to detect alternative isoforms, which raises concerns for the interpretation of ER-status in routine pathology. Future work should investigate the effects of alternative isoforms on patient survival and therapy response. An accurate annotation of ER isoforms will aid in interpretation of clinical data and inform functional studies to improve our understanding of the ER in health and disease.

Redox Modification of PKA-Cα Differentially Affects Its Substrate Selection.

The cyclic AMP-dependent protein kinase (PKA) plays an essential role in the regulation of many important cellular processes and is dysregulated in several pervasive diseases, including diabetes, cardiovascular disease, and various neurodegenerative disorders. Previous studies suggest that the alpha isoform of the catalytic subunit of PKA (PKA-Cα) is oxidized on C199, both in vitro and in situ. However, the molecular consequences of these modifications on PKA-Cα's substrate selection remain largely unexplored. C199 is located on the P + 1 loop within PKA-Cα's active site, suggesting that redox modification may affect its kinase activity. Given the proximity of C199 to the substrate binding pocket, we hypothesized that oxidation could differentially alter PKA-Cα's activity toward its substrates. To this end, we examined the effects of diamide- and H2O2-dependent oxidation on PKA-Cα's activity toward select peptide and protein substrates using a combination of biochemical (i.e., trans-phosphorylation assays and steady-state kinetics analysis) and biophysical (i.e., surface plasmon resonance and fluorescence polarization assays) strategies. These studies suggest that redox modification of PKA-Cα differentially affects its activity toward different substrates. For instance, we found that diamide-mediated oxidation caused a marked decrease in PKA-Cα's activity toward some substrates (e.g., Kemptide and CREBtide) while having little effect on others (e.g., Crosstide). In contrast, H2O2-dependent oxidation of PKA-Cα led to an increase in its activity toward each of the substrates at relatively low H2O2 concentrations, with differential effects at higher peroxide concentrations. Together, these studies offer novel insights into crosstalk between redox- and phosphorylation-dependent signaling pathways mediated by PKA. Likewise, since C199 is highly conserved among AGC kinase family members, they also lay the foundation for future studies designed to elucidate the role of redox-dependent modification of kinase substrate selection in physiological and pathological states.

RNA guanine-quadruplexes as novel regulators of translation and alternative splicing of tr alpha isoforms

RNA guanine-quadruplexes as novel regulators of translation and alternative splicing of tr alpha isoforms

CaMKII autophosphorylation can occur between holoenzymes without subunit exchange.

The dodecameric protein kinase CaMKII is expressed throughout the body. The alpha isoform is responsible for synaptic plasticity and participates in memory through its phosphorylation of synaptic proteins. Its elaborate subunit organization and propensity for autophosphorylation allow it to preserve neuronal plasticity across space and time. The prevailing hypothesis for the spread of CaMKII activity, involving shuffling of subunits between activated and naive holoenzymes, is broadly termed subunit exchange. In contrast to the expectations of previous work, we found little evidence for subunit exchange upon activation, and no effect of restraining subunits to their parent holoenzymes. Rather, mass photometry, crosslinking mass spectrometry, single molecule TIRF microscopy and biochemical assays identify inter-holoenzyme phosphorylation (IHP) as the mechanism for spreading phosphorylation. The transient, activity-dependent formation of groups of holoenzymes is well suited to the speed of neuronal activity. Our results place fundamental limits on the activation mechanism of this kinase.

Neflamapimod inhibits endothelial cell activation, adhesion molecule expression, leukocyte attachment and vascular inflammation by inhibiting p38 MAPKα and NF-κB signaling

Neflamapimod, a selective inhibitor of the alpha isoform of p38 mitogen-activated protein kinase (MAPKα), was investigated for its potential to inhibit lipopolysaccharide (LPS)-induced activation of endothelial cells (ECs), adhesion molecule induction, and subsequent leukocyte attachment to EC monolayers. These events are known to contribute to vascular inflammation and cardiovascular dysfunction. Our results demonstrate that LPS treatment of cultured ECs and rats leads to significant upregulation of adhesion molecules, both in vitro and in vivo, which can be effectively inhibited by neflamapimod treatment. Western blotting data further reveals that neflamapimod inhibits LPS-induced phosphorylation of p38 MAPKα and the activation of NF-κB signaling in ECs. Additionally, leukocyte adhesion assays demonstrate a substantial reduction in leukocyte attachment to cultured ECs and the aorta lumen of rats treated with neflamapimod. Consistent with vascular inflammation, LPS-treated rat arteries exhibit significantly diminished vasodilation response to acetylcholine, however, arteries from rats treated with neflamapimod maintain their vasodilation capacity, demonstrating its ability to limit LPS-induced vascular inflammation. Overall, our data demonstrate that neflamapimod effectively inhibits endothelium activation, adhesion molecule expression, and leukocyte attachment, thereby reducing vascular inflammation.