A p53-phosphoinositide signalosome regulates nuclear AKT activation

Da-Chai-Hu-Tang Formula inhibits the progression and metastasis in HepG2 cells through modulation of the PI3K/AKT/STAT3-induced cell cycle arrest and apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Da-Chai-Hu-Tang (DCHT), a Chinese traditional herbal compound, has been utilized for the treatment of Hepatic diseases in China for over 1800 years. The DCHT formula contains eight herbals: Bupleurum chinense DC. (chaihu), Scutellaria baicalensis Georgi (huangqin), Paeonia lactiflora Pall. (baishao), Pinellia ternata (Thunb.) Makino (banxia), Rheum officinale Baill. (dahuang), Citrus × aurantium L. (zhishi), Zingiber officinale Roscoe (shengjiang), Ziziphus jujuba Mill. (dazao). Clinical studies have demonstrated the effectiveness of DCHT in hepatocellular carcinoma (HCC) and its ability to enhance the immunity of patients with hepatocellular carcinoma. A total of 20 Chinese articles have been published on the use of DCHT in treating HCC.

AIM OF THE STUDY

The study aimed to validate the effect of DCHT in HCC cells and to identify related targets (TP53, AKT1, BCL2, STAT3) in treating HCC by DCHT in vitro experiments.

MATERIALS AND METHODS

Cell proliferation and migration were investigated in vitro. Flow cytometry analysis was used to evaluate the cell cycle and apoptosis. Apoptotic bodies in HepG2 cells were observed using a confocal microscope. Biochemical detection was employed to analyze LDH release, MDA levels, and SOD levels. Bioinformatics analysis was used to predict core targets between DCHT and HCC, as well as potential signaling pathways. The protein levels of metastasis-associated, apoptosis, and PI3K, AKT, p-AKT, and STAT3 were further determined through Western blotting.

RESULTS

Following treatment with DCHT, the inhibition of viability, migration, and G2/M arrest was observed in HepG2 cells. Flow cytometry analysis and Morphological apoptosis studies provided evidence that DCHT could induce apoptosis in HepG2 cells. Biochemical detection revealed that DCHT could increase LDH release and the level of MDA, and inhibit the viability of the SOD. Bioinformatics analysis identified key targets such as TP53, AKT1, BCL2, STAT3. The PI3K/AKT/STAT3 signaling pathway emerged as a critical pathway in the KEGG enrichment analysis. Western blotting results indicated that DCHT could enhance the expression of E-cadherin, p53, and Bax, while reducing the content of N-cadherin, Bcl-2, PI3K, p-AKT, AKT1, and STAT3.

CONCLUSIONS

The results proved that DCHT could inhibit the progression and metastasis of HCC by regulating the expression of E-cadherin, N-cadherin, p53, Bax, Bcl-2, PI3K, p-AKT, AKT, and STAT3 through the PI3K/AKT/STAT3 signaling pathway.

HMGA2 promotes resistance against paclitaxel by targeting the p53 signaling pathway in colorectal cancer cells

Colorectal cancer is one of the most common malignancies and ranks second in terms of cancer-related mortality worldwide due to its metastasis, drug resistance, and reoccurrence. High-mobility gene group A2 (HMGA2) is overexpressed in colorectal cancer, contributing to the aggressiveness of tumor malignance, and promotes drug resistance in many types of cancer. However, the underlying molecular mechanism of HMGA2 is yet to be elucidated. In this study, we showed that HMGA2 is overexpressed in colorectal cancer tissue, and knockdown of HMGA2 significantly inhibited colorectal cancer cell growth and migratory capability. HMGA2 regulates the cancer cell response to a widely used anti-cancer drug, paclitaxel (PTX). HMGA2 knockdown increased cell death, whereas HMGA2 overexpression decreased cell death after PTX treatment. Furthermore, lower reactive oxygen species (ROS) levels and mitochondrial potential were detected in HMGA2 overexpression cells after PTX treatment. However, HMGA2 knockdown produced the opposite effect. RNA sequencing showed a p53 signaling pathway-dependent regulation in HMGA2 knockdown cells. Combined with p53 inhibitors and HMGA2 knockdown, a synergetic effect of more cell death was observed in colorectal cancer cells after PTX treatment. Thus, we showed that HMGA2 can activate p53 signaling to regulate colorectal cancer cell death after PTX treatment. Altogether, our results reveal novel insights into the molecular mechanisms underlying HMGA2-mediated cancer cell resistance against PTX and highlight the potential of targeting HMGA2 and p53 signaling for the therapeutic investigation of colorectal cancer.

TRAF6-mediated ubiquitination of AKT1 in the nucleus occurs in a β-arrestin2-dependent manner upon insulin stimulation

AKT, also known as protein kinase B (PKB), serves as a crucial regulator of numerous biological functions, including cell growth, metabolism, and tumorigenesis. Increasing evidence suggests that the kinase activity of AKT is regulated via ubiquitination by various E3 ligase enzymes in response to different stimuli. However, the molecular mechanisms underlying insulin-induced AKT ubiquitination are not yet fully understood. Here, we show that activation of the insulin receptor (IR) leads to enhanced ubiquitination of AKT1 at K8 and K14 residues, facilitated by the cytosolic E3 ubiquitin ligase enzyme, TRAF6. Further investigation using AKT1 mutants with modified nucleocytoplasmic shuttling properties reveals that TRAF6-mediated AKT1 ubiquitination occurs within the nucleus in a β-Arr2-dependent manner. The nuclear entry of TRAF6 depends on importin β1, while β-Arr2 regulates this process by facilitating the interaction between TRAF6 and importin β1. Additionally, the ubiquitination of AKT1 is essential for its translocation to the activated IR on the plasma membrane, where it plays a functional role in recruiting Glut4 and facilitating glucose uptake. This study uncovers the cellular components and processes involved in insulin-induced ubiquitination and activation of AKT1, providing insights and detailed strategies for manipulating AKT1.

A p85 isoform switch enhances PI3K activation on endosomes by a MAP4- and PI3P-dependent mechanism

Phosphatidylinositol 3-kinase α (PI3Kα) is a heterodimer of p110α catalytic and p85 adaptor subunits that is activated by agonist-stimulated receptor tyrosine kinases. Although p85α recruits p110α to activated receptors on membranes, p85α loss, which occurs commonly in cancer, paradoxically promotes agonist-stimulated PI3K/Akt signaling. p110α localizes to microtubules via microtubule-associated protein 4 (MAP4), facilitating its interaction with activated receptor kinases on endosomes to initiate PI3K/Akt signaling. Here, we demonstrate that in response to agonist stimulation and p85α knockdown, the residual p110α, coupled predominantly to p85β, exhibits enhanced recruitment with receptor tyrosine kinases to endosomes. Moreover, the p110α C2 domain binds PI3-phosphate, and this interaction is also required to recruit p110α to endosomes and for PI3K/Akt signaling. Stable knockdown of p85α, which mimics the reduced p85α levels observed in cancer, enhances cell growth and tumorsphere formation, and these effects are abrogated by MAP4 or p85β knockdown, underscoring their role in the tumor-promoting activity of p85α loss.

Nuclear patterns of phosphatidylinositol 4,5- and 3,4-bisphosphate revealed by super-resolution microscopy differ between the consecutive stages of RNA polymerase II transcription

Phosphatidylinositol phosphates are powerful signaling molecules that orchestrate signaling and direct membrane trafficking in the cytosol. Interestingly, phosphatidylinositol phosphates also localize within the membrane-less compartments of the cell nucleus, where they participate in the regulation of gene expression. Nevertheless, current models of gene expression, which include condensates of proteins and nucleic acids, do not include nuclear phosphatidylinositol phosphates. This gap is partly a result of the missing detailed analysis of the subnuclear distribution of phosphatidylinositol phosphates and their relationships with gene expression. Here, we used quantitative dual-color direct stochastic optical reconstruction microscopy to analyze the nanoscale co-patterning between RNA polymerase II transcription initiation and elongation markers with respect to phosphatidylinositol 4,5- or 3,4-bisphosphate in the nucleoplasm and nuclear speckles and compared it with randomized data and cells with inhibited transcription. We found specific co-patterning of the transcription initiation marker P-S5 with phosphatidylinositol 4,5-bisphosphate in the nucleoplasm and with phosphatidylinositol 3,4-bisphosphate at the periphery of nuclear speckles. We showed the specific accumulation of the transcription elongation marker PS-2 and of nascent RNA in the proximity of phosphatidylinositol 3,4-bisphosphate associated with nuclear speckles. Taken together, this shows that the distinct spatial associations between the consecutive stages of RNA polymerase II transcription and nuclear phosphatidylinositol phosphates exhibit specificity within the gene expression compartments. Thus, in analogy to the cellular membranes, where phospholipid composition orchestrates signaling pathways and directs membrane trafficking, we propose a model in which the phospholipid identity of gene expression compartments orchestrates RNA polymerase II transcription.

Nuclear phosphoinositide signaling promotes YAP/TAZ-TEAD transcriptional activity in breast cancer

The Hippo pathway effectors Yes-associated protein 1 (YAP) and its homolog TAZ are transcriptional coactivators that control gene expression by binding to TEA domain (TEAD) family transcription factors. The YAP/TAZ-TEAD complex is a key regulator of cancer-specific transcriptional programs, which promote tumor progression in diverse types of cancer, including breast cancer. Despite intensive efforts, the YAP/TAZ-TEAD complex in cancer has remained largely undruggable due to an incomplete mechanistic understanding. Here, we report that nuclear phosphoinositides function as cofactors that mediate the binding of YAP/TAZ to TEADs. The enzymatic products of phosphoinositide kinases PIPKIα and IPMK, including phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) and phosphatidylinositol 3,4,5-trisphosphate (P(I3,4,5)P3), bridge the binding of YAP/TAZ to TEAD. Inhibiting these kinases or the association of YAP/TAZ with PI(4,5)P2 and PI(3,4,5)P3 attenuates YAP/TAZ interaction with the TEADs, the expression of YAP/TAZ target genes, and breast cancer cell motility. Although we could not conclusively exclude the possibility that other enzymatic products of IPMK such as inositol phosphates play a role in the mechanism, our results point to a previously unrecognized role of nuclear phosphoinositide signaling in control of YAP/TAZ activity and implicate this pathway as a potential therapeutic target in YAP/TAZ-driven breast cancer.

PTEN: an emerging target in rheumatoid arthritis?

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a critical tumor suppressor protein that regulates various biological processes such as cell proliferation, apoptosis, and inflammatory responses by controlling the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PI3K/AKT) signaling pathway. PTEN plays a crucial role in the pathogenesis of rheumatoid arthritis (RA). Loss of PTEN may contribute to survival, proliferation, and pro-inflammatory cytokine release of fibroblast-like synoviocytes (FLS). Also, persistent PI3K signaling increases myeloid cells' osteoclastic potential, enhancing localized bone destruction. Recent studies have shown that the expression of PTEN protein in the synovial lining of RA patients with aggressive FLS is minimal. Experimental upregulation of PTEN protein expression could reduce the damage caused by RA. Nonetheless, a complete comprehension of aberrant PTEN drives RA progression and its interactions with other crucial molecules remains elusive. This review is dedicated to promoting a thorough understanding of the signaling mechanisms of aberrant PTEN in RA and aims to furnish pertinent theoretical support for forthcoming endeavors in both basic and clinical research within this domain.

Lipid transfer proteins and a PI 4-kinase initiate nuclear phosphoinositide signaling

Phosphoinositide (PIP n ) messengers are present in non-membranous regions of nuclei, where they are assembled into a phosphatidylinositol (PI) 3-kinase (PI3K)/Akt pathway that is distinct from the cytosolic membrane-localized pathway. In the nuclear pathway, PI kinases/phosphatases bind the p53 tumor suppressor protein (wild-type and mutant) to generate p53-PIP n complexes that regulate Akt activation. However, this pathway is dependent on poorly characterized nuclear PIP n pools. Here we report that PI transfer proteins (PITPs), which transport PI between membranes to enable membrane-localized PIP n synthesis, accumulate in the nucleoplasm in response to stress and supply nuclear PIP n pools. PITPα/β and the PI 4-kinase PI4KIIα bind p53 and are required to generate p53-PI4P, which is further phosphorylated to synthesize p53-PIP n complexes that regulate nuclear Akt activation and stress-resistance. Remarkably, PITPα/β and PI4KIIα initiate PIP n -linkage to multiple proteins that are detectable by immunoblotting and [ 3 H] myo -inositol metabolic labeling and are resistant to denaturation, suggesting a posttranslational modification.

In brief

Phosphatidylinositol transfer proteins initiate the nuclear PIP n -linked protein network in membrane-free regions.

Nuclear Phospholipids and Signaling: An Update of the Story

In the last three decades, the presence of phospholipids in the nucleus has been shown and thoroughly investigated. A considerable amount of interest has been raised about nuclear inositol lipids, mainly because of their role in signaling acting. Here, we review the main issues of nuclear phospholipid localization and the role of nuclear inositol lipids and their related enzymes in cellular signaling, both in physiological and pathological conditions.

The human adenovirus PI3K-Akt activator E4orf1 is targeted by the tumor suppressor p53

Human adenoviruses (HAdV) are classified as DNA tumor viruses due to their potential to mediate oncogenic transformation in non-permissive mammalian cells and certain human stem cells. To achieve transformation, the viral early proteins of the E1 and E4 regions must block apoptosis and activate proliferation: the former predominantly through modulating the cellular tumor suppressor p53 and the latter by activating cellular pro-survival and pro-metabolism protein cascades, such as the phosphoinositide 3-kinase (PI3K-Akt) pathway, which is activated by HAdV E4orf1. Focusing on HAdV-C5, we show that E4orf1 is necessary and sufficient to stimulate Akt activation through phosphorylation in H1299 cells, which is not only hindered but repressed during HAdV-C5 infection with a loss of E4orf1 function in p53-positive A549 cells. Contrary to other research, E4orf1 localized not only in the common, cytoplasmic PI3K-Akt-containing compartment, but also in distinct nuclear aggregates. We identified a novel inhibitory mechanism, where p53 selectively targeted E4orf1 to destabilize it, also stalling E4orf1-dependent Akt phosphorylation. Co-IP and immunofluorescence studies showed that p53 and E4orf1 interact, and since p53 is bound by the HAdV-C5 E3 ubiquitin ligase complex, we also identified E4orf1 as a novel factor interacting with E1B-55K and E4orf6 during infection; overexpression of E4orf1 led to less-efficient E3 ubiquitin ligase-mediated proteasomal degradation of p53. We hypothesize that p53 specifically subverts the pro-survival function of E4orf1-mediated PI3K-Akt activation to protect the cell from metabolic hyper-activation or even transformation.IMPORTANCEHuman adenoviruses (HAdV) are nearly ubiquitous pathogens comprising numerous subtypes that infect various tissues and organs. Among many encoded proteins that facilitate viral replication and subversion of host cellular processes, the viral E4orf1 protein has emerged as an intriguing yet under-investigated player in the complex interplay between the virus and its host. Nonetheless, E4orf1 has gained attention as a metabolism activator and oncogenic agent, while recent research is showing that E4orf1 may play a more important role in modulating the cellular pathways such as phosphoinositide 3-kinase-Akt-mTOR. Our study reveals a novel and general impact of E4orf1 on host mechanisms, providing a novel basis for innovative antiviral strategies in future therapeutic settings. Ongoing investigations of the cellular pathways modulated by HAdV are of great interest, particularly since adenovirus-based vectors actually serve as vaccine or gene vectors. HAdV constitute an ideal model system to analyze the underlying molecular principles of virus-induced tumorigenesis.

Nanoparticles targeting mutant p53 overcome chemoresistance and tumor recurrence in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) shows high drug resistance and leads to low survival due to the high level of mutated Tumor Protein p53 (TP53). Cisplatin is a first-line treatment option for NSCLC, and the p53 mutation is a major factor in chemoresistance. We demonstrate that cisplatin chemotherapy increases the risk of TP53 mutations, further contributing to cisplatin resistance. Encouragingly, we find that the combination of cisplatin and fluvastatin can alleviate this problem. Therefore, we synthesize Fluplatin, a prodrug consisting of cisplatin and fluvastatin. Then, Fluplatin self-assembles and is further encapsulated with poly-(ethylene glycol)-phosphoethanolamine (PEG-PE), we obtain Fluplatin@PEG-PE nanoparticles (FP NPs). FP NPs can degrade mutant p53 (mutp53) and efficiently trigger endoplasmic reticulum stress (ERS). In this study, we show that FP NPs relieve the inhibition of cisplatin chemotherapy caused by mutp53, exhibiting highly effective tumor suppression and improving the poor NSCLC prognosis.

Environmental pollutants and phosphoinositide signaling in autoimmunity

Environmental pollution stands as one of the most critical challenges affecting human health, with an estimated mortality rate linked to pollution-induced non-communicable diseases projected to range from 20% to 25%. These pollutants not only disrupt immune responses but can also trigger immunotoxicity. Phosphoinositide signaling, a pivotal regulator of immune responses, plays a central role in the development of autoimmune diseases and exhibits high sensitivity to environmental stressors. Among these stressors, environmental pollutants have become increasingly prevalent in our society, contributing to the initiation and exacerbation of autoimmune conditions. In this review, we summarize the intricate interplay between phosphoinositide signaling and autoimmune diseases within the context of environmental pollutants and contaminants. We provide an up-to-date overview of stress-induced phosphoinositide signaling, discuss 14 selected examples categorized into three groups of environmental pollutants and their connections to immune diseases, and shed light on the associated phosphoinositide signaling pathways. Through these discussions, this review advances our understanding of how phosphoinositide signaling influences the coordinated immune response to environmental stressors at a biological level. Furthermore, it offers valuable insights into potential research directions and therapeutic targets aimed at mitigating the impact of environmental pollutants on the pathogenesis of autoimmune diseases. SYNOPSIS: Phosphoinositide signaling at the intersection of environmental pollutants and autoimmunity provides novel insights for managing autoimmune diseases aggravated by pollutants.

The expanding roles of PI4P and PI(4,5)P2 at the plasma membrane: Role of phosphatidylinositol transfer proteins

Phosphoinositides are phosphorylated derivatives of phosphatidylinositol, a phospholipid that is synthesised at the endoplasmic reticulum. The plasma membrane contains the enzymes to phosphorylate phosphatidylinositol and is therefore rich in the phosphorylated derivatives, PI4P and PI(4,5)P2. PI(4,5)P2 is a substrate for phospholipase C and during cell signaling, PI(4,5)P2 levels are reduced. Here I discuss a family of proteins, phosphatidylinositol transfer proteins (PITPs) that can restore PI(4,5)P2 levels.

Elucidation of the mechanism of action of ailanthone in the treatment of colorectal cancer: integration of network pharmacology, bioinformatics analysis and experimental validation

Background: Ailanthone, a small compound derived from the bark of Ailanthus altissima (Mill.) Swingle, has several anti-tumour properties. However, the activity and mechanism of ailanthone in colorectal cancer (CRC) remain to be investigated. This study aims to comprehensively investigate the mechanism of ailanthone in the treatment of CRC by employing a combination of network pharmacology, bioinformatics analysis, and molecular biological technique. Methods: The druggability of ailanthone was examined, and its targets were identified using relevant databases. The RNA sequencing data of individuals with CRC obtained from the Cancer Genome Atlas (TCGA) database were analyzed. Utilizing the R programming language, an in-depth investigation of differentially expressed genes was carried out, and the potential target of ailanthone for anti-CRC was found. Through the integration of protein-protein interaction (PPI) network analysis, GO and KEGG enrichment studies to search for the key pathway of the action of Ailanthone. Then, by employing molecular docking verification, flow cytometry, Transwell assays, and Immunofluorescence to corroborate these discoveries. Results: Data regarding pharmacokinetic parameters and 137 target genes for ailanthone were obtained. Leveraging The Cancer Genome Atlas database, information regarding 2,551 differentially expressed genes was extracted. Subsequent analyses, encompassing protein-protein interaction network analysis, survival analysis, functional enrichment analysis, and molecular docking verification, revealed the PI3K/AKT signaling pathway as pivotal mediators of ailanthone against CRC. Additionally, the in vitro experiments indicated that ailanthone substantially affects the cell cycle, induces apoptosis in CRC cells (HCT116 and SW620 cells), and impedes the migration and invasion capabilities of these cells. Immunofluorescence staining showed that ailanthone significantly inhibited the phosphorylation of AKT protein and suppressed the activation of the PI3K/AKT signaling pathway, thereby inhibiting the proliferation and metastasis of CRC cells. Conclusion: Therefore, our findings indicate that Ailanthone exerts anti-CRC effects primarily by inhibiting the activation of the PI3K/AKT pathway. Additionally, we propose that Ailanthone holds potential as a therapeutic agent for the treatment of human CRC.

The mTORC2 signaling network: targets and cross-talks

The mechanistic target of rapamycin, mTOR, controls cell metabolism in response to growth signals and stress stimuli. The cellular functions of mTOR are mediated by two distinct protein complexes, mTOR complex 1 (mTORC1) and mTORC2. Rapamycin and its analogs are currently used in the clinic to treat a variety of diseases and have been instrumental in delineating the functions of its direct target, mTORC1. Despite the lack of a specific mTORC2 inhibitor, genetic studies that disrupt mTORC2 expression unravel the functions of this more elusive mTOR complex. Like mTORC1 which responds to growth signals, mTORC2 is also activated by anabolic signals but is additionally triggered by stress. mTORC2 mediates signals from growth factor receptors and G-protein coupled receptors. How stress conditions such as nutrient limitation modulate mTORC2 activation to allow metabolic reprogramming and ensure cell survival remains poorly understood. A variety of downstream effectors of mTORC2 have been identified but the most well-characterized mTORC2 substrates include Akt, PKC, and SGK, which are members of the AGC protein kinase family. Here, we review how mTORC2 is regulated by cellular stimuli including how compartmentalization and modulation of complex components affect mTORC2 signaling. We elaborate on how phosphorylation of its substrates, particularly the AGC kinases, mediates its diverse functions in growth, proliferation, survival, and differentiation. We discuss other signaling and metabolic components that cross-talk with mTORC2 and the cellular output of these signals. Lastly, we consider how to more effectively target the mTORC2 pathway to treat diseases that have deregulated mTOR signaling.

DHCR24 in Tumor Diagnosis and Treatment: A Comprehensive Review

As an important nutrient in the human body, cholesterol can not only provide structural components for the body's cells, but also can be transformed into a variety of active substances to regulate cell signaling pathways. As an important cholesterol synthase, DHCR24 participates in important regulatory processes in the body. The application of DHCR24 in tumor clinical diagnosis and treatment also attracts much attention. This article reviews the structure and regulatory characteristics of DHCR24, and the research of DHCR24 on tumor progression. We summarize the possible mechanisms of DHCR24 promoting tumor progression through reactive oxygen species (ROS), p53, Ras and PI3K-AKT pathways. Through our review, we hope to provide more research ideas and reference value for the application of DHCR24 in tumor prevention and treatment.

Aspirin boosts the synergistic effect of EGFR/p53 inhibitors on lung cancer cells by regulating AKT/mTOR and p53 pathways

The regimen of afatinib and vinorelbine has been used to treat breast or lung cancer cells with some limitations. Aspirin alone or in combination with other agents has shown unique efficacy in the treatment of cancer. We designed a preclinical study to investigate whether the triple therapy of aspirin, afatinib, and vinorelbine could synergistically inhibit the growth of p53 wild-type nonsmall cell lung cancer (NSCLC) cells. Three NSCLC cells A549, H460, and H1975 were selected to study the effect of triple therapy on cell proliferation and apoptosis. Compared to single agents, triple therapy synergistically inhibited the proliferation of lung cancer cells with combination index <1. Meanwhile, the therapeutic index of triple therapy was superior to that of single agents, indicating a balance between efficacy and safety in the combination of three agents. Mechanistic studies showed that triple therapy significantly induced apoptosis by decreasing mitochondrial membrane potential, increasing reactive oxygen species, and regulating mitochondria-related proteins. Moreover, epidermal growth factor receptor (EGFR) downstream signaling proteins including JNK, AKT, and mTOR were dramatically suppressed and p53 was substantially increased after NSCLC cells were exposed to the triple therapy. We provided evidence that the triple therapy of aspirin, afatinib and vinorelbine synergistically inhibited lung cancer cell growth through inactivation of the EGFR/AKT/mTOR pathway and accumulation of p53, providing a new treatment strategy for patients with p53 wild-type NSCLC.

Blue light impairs cornea and corneal wound healing by downregulating VCAM1 partly

This study aimed to investigate the effects of long-term pollution from different wavelengths of light on the corneal epithelium (CE) and identify potential biomarkers. Rabbits were exposed to red, green, blue, white, and environmental light for 6 weeks. The CE was assessed using various techniques such as fluorescein sodium staining, transcriptome sequencing, electron microscopy, and molecular assays. In human corneal epithelial cells (hCECs), the downregulation of vascular cell adhesion molecule 1 (VCAM1) in response to blue light (BL) pollution was observed. This downregulation of VCAM1 inhibited migration, increased reactive oxygen species (ROS) levels, and apoptosis, and inhibited the AKT/p70 S6 kinase cascade in hCECs. Animal experiments confirmed that BL pollution caused similar effects on the rabbit cornea, including increased ROS production, apoptosis, delayed wound healing, and decreased VCAM1 expression. Overall, BL-induced VCAM1 downregulation may impair CE and wound healing and promote ROS and apoptosis in vitro and in vivo.

Mutant p53 gain-of-function stimulates canonical Wnt signaling via PI3K/AKT pathway in colon cancer

Aberrant canonical Wnt signaling is a hallmark of colon cancer. The TP53 tumor suppressor gene is altered in many solid tumors, including colorectal cancer, resulting in mutant versions of p53 (mut-p53) that lose their tumor suppressor capacities and acquire new-oncogenic functions (GOFs) critical for disease progression. Although the mechanisms related to mut-p53 GOF have been explored extensively, the relevance of mut-p53 in the canonical Wnt pathway is not well defined. This work investigated the influence of mut-p53 compared to wt-p53 in β-catenin-dependent Wnt signaling. Using the TCGA public data from Pan-Cancer and the GEPIA2 platform, an in silico analysis of wt-p53 versus mut-p53 genotyped colorectal cancer patients showed that TP53 (p53) and CTNNB1 (β-catenin) are significantly overexpressed in colorectal cancer, compared with normal tissue. Using p53 overexpression or p53 knockdown assays of wt-p53 or mut-p53, we found that while wt-p53 antagonizes canonical Wnt signaling, mut-p53 induces the opposite effect, improving the β-catenin-dependent transcriptional activity and colony formation ability of colon cancer cells, which were both decreased by mut-p53 knockdown expression. The mechanism involved in mut-p53-induced activation of canonical Wnt appears to be via AKT-mediated phosphorylation of Ser 552 of β-catenin, which is known to stabilize and enhance its transcriptional activity. We also found that while wt-p53 expression contributes to 5-FU sensitivity in colon cancer cells, the RITA p53 reactivating molecule counteracted the resistance against 5-FU in cells expressing mut-p53. Our results indicate that mut-p53 GOF acts as a positive regulator of canonical Wnt signaling and participates in the induction of resistance to 5-FU in colon cancer cells.

Regulation of NRF2 by Phosphoinositides and Small Heat Shock Proteins

Reactive oxygen species (ROS) are generated by aerobic metabolism, and their deleterious effects are buffered by the cellular antioxidant response, which prevents oxidative stress. The nuclear factor erythroid 2-related factor 2 (NRF2) is a master transcriptional regulator of the antioxidant response. Basal levels of NRF2 are kept low by ubiquitin-dependent degradation of NRF2 by E3 ligases, including the Kelch-like ECH-associated protein 1 (KEAP1). Here, we show that the stability and function of NRF2 is regulated by the type I phosphatidylinositol phosphate kinase g (PIPKIg), which binds NRF2 and transfers its product phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P 2 ) to NRF2. PtdIns(4,5)P 2 binding recruits the small heat shock protein HSP27 to the complex. Silencing PIPKIg or HSP27 destabilizes NRF2, reduces expression of its target gene HO-1, and sensitizes cells to oxidative stress. These data demonstrate an unexpected role of phosphoinositides and HSP27 in regulating NRF2 and point to PIPKIg and HSP27 as drug targets to destabilize NRF2 in cancer.

In brief

Phosphoinositides are coupled to NRF2 by PIPKIγ, and HSP27 is recruited and stabilizes NRF2, promoting stress-resistance.

Tumor suppressor p53 mediates interleukin-6 expression to enable cancer cell evasion of genotoxic stress

The tumor suppressor p53 primarily functions as a mediator of DNA damage-induced cell death, thereby contributing to the efficacy of genotoxic anticancer therapeutics. Here, we show, on the contrary, that cancer cells can employ genotoxic stress-induced p53 to acquire treatment resistance through the production of the pleiotropic cytokine interleukin (IL)-6. Mechanistically, DNA damage, either repairable or irreparable, activates p53 and stimulates Caspase-2-mediated cleavage of its negative regulator mouse double minute 2 (MDM2) creating a positive feedback loop that leads to elevated p53 protein accumulation. p53 transcriptionally controls the major adenosine triphosphate (ATP) release channel pannexin 1 (Panx1), which directs IL-6 induction via a mechanism dependent on the extracellular ATP-activated purinergic P2 receptors as well as their downstream intracellular calcium (iCa2+)/PI3K/Akt/NF-ĸB signaling pathway. Thus, p53 silencing impairs Panx1 and IL-6 expression and renders cancer cells sensitive to genotoxic stress. Moreover, we confirm that IL-6 hampers the effectiveness of genotoxic anticancer agents by mitigating DNA damage, driving the expression of anti-apoptotic Bcl-2 family genes, and maintaining the migratory and invasive properties of cancer cells. Analysis of patient survival and relevant factors in lung cancer and pan-cancer cohorts supports the prognostic and clinical values of Panx1 and IL-6. Notably, IL-6 secreted by cancer cells during genotoxic treatments promotes the polarization of monocytic THP-1-derived macrophages into an alternative (M2-like) phenotype that exhibits impaired anti-survival activities but enhanced pro-metastatic effects on cancer cells as compared to nonpolarized macrophages. Our study reveals the precise mechanism for genotoxic-induced IL-6 and suggests that targeting p53-mediated IL-6 may improve the responsiveness of cancer cells to genotoxic anticancer therapy.

Regulation of Phosphoinositide Signaling by Scaffolds at Cytoplasmic Membranes

Cytoplasmic phosphoinositides (PI) are critical regulators of the membrane-cytosol interface that control a myriad of cellular functions despite their low abundance among phospholipids. The metabolic cycle that generates different PI species is crucial to their regulatory role, controlling membrane dynamics, vesicular trafficking, signal transduction, and other key cellular events. The synthesis of phosphatidylinositol (3,4,5)-triphosphate (PI3,4,5P3) in the cytoplamic PI3K/Akt pathway is central to the life and death of a cell. This review will focus on the emerging evidence that scaffold proteins regulate the PI3K/Akt pathway in distinct membrane structures in response to diverse stimuli, challenging the belief that the plasma membrane is the predominant site for PI3k/Akt signaling. In addition, we will discuss how PIs regulate the recruitment of specific scaffolding complexes to membrane structures to coordinate vesicle formation, fusion, and reformation during autophagy as well as a novel lysosome repair pathway.

CEP55 as a promising biomarker and therapeutic target on gallbladder cancer

Introduction

Gallbladder cancer (GBC) is a highly malignant biliary tumor with a poor prognosis. As existing therapies for advanced metastatic GBC are rarely effective, there is an urgent need to identify more effective targets for treatment.

Methods

Hub genes of GBC were identified by bioinformatics analysis and their expression in GBC was analyzed by tissue validation. The biological role of CEP55 in GBC cell and the underlying mechanism of the anticancer effect of CEP55 knockdown were evaluated via CCK8, colony formation assay, EDU staining, flow cytometry, western blot, immunofluorescence, and an alkaline comet assay.

Results

We screened out five hub genes of GBC, namely PLK1, CEP55, FANCI, NEK2 and PTTG1. CEP55 is not only overexpressed in the GBC but also correlated with advanced TNM stage, differentiation grade and poorer survival. After CEP55 knockdown, the proliferation of GBC cells was inhibited with cell cycle arrest in G2/M phase and DNA damage. There was a marked increase in the apoptosis of GBC cells in the siCEP55 group. Besides, in vivo, CEP55 inhibition attenuated the growth and promoted apoptosis of GBC cells. Mechanically, the tumor suppressor effect of CEP55 knockdown is associated with dysregulation of the AKT and ERK signaling networks.

Discussion

These data not only demonstrate that CEP55 is identified as a potential independent predictor crucial to the diagnosis and prognosis of gallbladder cancer but also reveal the possibility for CEP55 to be used as a promising target in the treatment of GBC.

Phosphorylation of AKT by lysyl oxidase-like 2 activates the PI3K/AKT signaling pathway to promote proliferation, invasion and metastasis in esophageal squamous carcinoma

OBJECTIVE

Esophageal squamous cell carcinoma (ESCC) is a common and aggressive malignancy of the gastrointestinal tract for which therapeutic options are scarce. This study screens for LOXL2, a key gene in ESCC, and explains the molecular mechanism by which it promotes the progression of ESCC.

METHODS

Immunohistochemical staining was performed to detect the expression level of LOXL2 in ESCC tissues and paraneoplastic tissues. CCK-8 and Transwell assays were performed to assess the effects of LOXL2 knockdown and overexpression on the proliferation, apoptosis, migration and invasion ability of ESCC cells. High-throughput sequencing analysis screens for molecular mechanisms of action by which LOXL2 promotes ESCC progression. Western blotting and qRT-PCR were used to determine the expression levels of relevant markers.

RESULTS

LOXL2 is positively expressed in ESCC and highly correlated with poor prognosis. Silencing LOXL2 significantly inhibited the proliferation, migration and invasive ability of ESCC cells, whereas overexpression showed the opposite phenotype. High-throughput sequencing suggested that LOXL2-associated differentially expressed genes were highly enriched in the PI3K/AKT signaling pathway. In vitro cellular assays confirmed that silencing LOXL2 significantly reduced PI3K, p-AKT^Thr308 and p-AKT^Ser473 gene and protein expression levels, while overexpression increased all three gene and protein levels, while AKT gene and protein expression levels were not significantly different.

CONCLUSION

This study found that LOXL2 may regulate the PI3K/AKT signaling pathway and exert protumor effects on ESCC cells through phosphorylation of AKT. LOXL2 may be a key clinical warning biomarker or therapeutic target for ESCC.

Nuclear PTEN's Functions in Suppressing Tumorigenesis: Implications for Rare Cancers

Phosphatase and tensin homolog (PTEN) encodes a tumor-suppressive phosphatase with both lipid and protein phosphatase activity. The tumor-suppressive functions of PTEN are lost through a variety of mechanisms across a wide spectrum of human malignancies, including several rare cancers that affect pediatric and adult populations. Originally discovered and characterized as a negative regulator of the cytoplasmic, pro-oncogenic phosphoinositide-3-kinase (PI3K) pathway, PTEN is also localized to the nucleus where it can exert tumor-suppressive functions in a PI3K pathway-independent manner. Cancers can usurp the tumor-suppressive functions of PTEN to promote oncogenesis by disrupting homeostatic subcellular PTEN localization. The objective of this review is to describe the changes seen in PTEN subcellular localization during tumorigenesis, how PTEN enters the nucleus, and the spectrum of impacts and consequences arising from disrupted PTEN nuclear localization on tumor promotion. This review will highlight the immediate need in understanding not only the cytoplasmic but also the nuclear functions of PTEN to gain more complete insights into how important PTEN is in preventing human cancers.

Transcription-independent functions of p53 in DNA repair pathway selection

Recently discovered transcription-independent features of p53 involve the choice of DNA damage repair pathway after PARylation, and p53's complex formation with phosphoinositide lipids, PI(4,5)P₂ . PARylation-mediated rapid accumulation of p53 at DNA damage sites is linked to the recruitment of downstream repair factors and tumor suppression. This links p53's capability to sense damaged DNA in vitro and its relevant functions in cells. Further, PI(4,5)P₂ rapidly accumulates at damage sites like p53 and complexes with p53, while it is required for ATR recruitment. These findings help explain how p53 and PI(4,5)P₂ maintain genome stability by directing DNA repair pathway choice. Additionally, there is a strong correlation between p53 sequence homology, genome mutation rates as well as lifespans across various mammalian species. Further investigation is required to better understand the connections between genome stability, tumor suppression, longevity and the transcriptional-independent function of p53.

Selenium-ruthenium complex blocks H1N1 influenza virus-induced cell damage by activating GPx1/TrxR1

Background: Influenza A (H1N1) virus is an acute respiratory infectious disease that causes massive morbidity and mortality worldwide. As an essential trace element, selenium is widely applied in the treatment of various diseases because of its functions of enhancing immune response, antioxidant and antiviral mutation. In this study, we constructed the selenium-containing metal complex drug delivery system Ru(biim)(PhenSe)₂ (RuSe), and investigated the anti-influenza virus efficacy and the potential antiviral mechanism for RuSe. Methods: The inhibitory effect of RuSe on influenza-mediated apoptosis was examined by cell count assay, cell cycle assay, Annenxin-V assay, TUNEL-DAPI assay and reactive oxygen species level determination. Virulence assay, PCR and neuraminidase inhibition assay revealed the inhibition of RuSe on influenza virus. At the level of animal experiments, two animal models were used to clarify the role of RuSe through HE staining, immunohistochemical staining, cytokine determination, selenium metabolism determination and selenium protein expression level determination. Results: The results of this study confirm that RuSe enhances the expression levels of selenium proteins GPx1 and TrxR1 by regulating selenium metabolism, thereby inhibiting viral replication and assembly and regulating virus-mediated mitochondria-related apoptosis. On the other hand, animal experiments show that RuSe can reduce lung tissue inflammation and inhibit lung tissue cell apoptosis in mice, and improve the survival state of mice. In addition, RuSe significantly improves the low immune response of Se-deficient mice by regulating selenium metabolism, and effectively alleviated lung fibrosis and lung tissue apoptosis in Se-deficient mice. Conclusions: This study suggests that RuSe provides a promising new approach for the clinical treatment of influenza virus.

AKTs do not translocate to the nucleus upon stimulation but AKT3 can constitutively signal from the nuclear envelope

AKT is a central signaling protein kinase that plays a role in the regulation of cellular survival metabolism and cell growth, as well as in pathologies such as diabetes and cancer. Human AKT consists of three isoforms (AKT1-3) that may fulfill different functions. Here, we report that distinct subcellular localization of the isoforms directly influences their activity and function. AKT1 is localized primarily in the cytoplasm, AKT2 in the nucleus, and AKT3 in the nucleus or nuclear envelope. None of the isoforms actively translocates into the nucleus upon stimulation. Interestingly, AKT3 at the nuclear envelope is constitutively phosphorylated, enabling a constant phosphorylation of TSC2 at this location. Knockdown of AKT3 induces moderate attenuation of cell proliferation of breast cancer cells. We suggest that in addition to the stimulation-induced activation of the lysosomal/cytoplasmic AKT1-TSC2 pathway, a subpopulation of TSC2 is constitutively inactivated by AKT3 at the nuclear envelope of transformed cells.

Immune Pathway and Gene Database (IMPAGT) Revealed the Immune Dysregulation Dynamics and Overactivation of the PI3K/Akt Pathway in Tumor Buddings of Cervical Cancer

Tumor budding (TB) is a small cluster of malignant cells at the invasive front of a tumor. Despite being an adverse prognosis marker, little research has been conducted on the tumor immune microenvironment of tumor buddings, especially in cervical cancer. Therefore, RNA sequencing was performed using 21 formalin-fixed, paraffin-embedded slides of cervical tissues, and differentially expressed genes (DEGs) were analyzed. Immune Pathway and Gene Database (IMPAGT) was generated for immune profiling. "Pathway in Cancer" was identified as the most enriched pathway for both up- and downregulated DEGs. Kyoto Encyclopedia of Genes and Genomes Mapper and Gene Ontology further revealed the activation of the PI3K/Akt signaling pathway. An IMPAGT analysis revealed immune dysregulation even at the tumor budding stage, especially in the PI3K/Akt/mTOR axis, with a high efficiency and integrity. These findings emphasized the clinical significance of tumor buddings and the necessity of blocking the overactivation of the PI3K/Akt/mTOR pathway to improve targeted therapy in cervical cancer.

Identification of copper metabolism and cuproptosis-related subtypes for predicting prognosis tumor microenvironment and drug candidates in hepatocellular carcinoma

Copper (Cu) is an essential element of organisms, which can affect the survival of cells. However, the role of copper metabolism and cuproptosis on hepatic carcinoma is still unclear. In this study, the TCGA database was used as the test set, and the ICGC database and self-built database were used as the validation set. We screened out a class of copper metabolism and cuproptosis-related genes (CMCRGs) that could influence hepatic carcinoma prognosis by survival analysis and differential comparison. Based on CMCRGs, patients were divided into two subtypes by cluster analysis. The C2 subtype was defined as the high copper related subtype, while the C1 subtype was defied as the low copper related subtype. At the clinical level, compared with the C1 subtype, the C2 subtype had higher grade pathological features, risk scores, and worse survival. In addition, the immune response and metabolic status also differed between C1 and C2. Specifically, C2 subtype had a higher proportion of immune cell composition and highly expressed immune checkpoint genes. C2 subtype had a higher TIDE score with a higher proportion of tumor immune dysfunction and exclusion. At the molecular level, the C2 subtype had a higher frequency of driver gene mutations (TP53 and OBSCN). Mechanistically, the single nucleotide polymorphisms of C2 subtype had a very strong transcriptional strand bias for C>A mutations. Copy number variations in the C2 subtype were characterized by LOXL3 CNV gain, which also showed high association with PDCD1/CTLA4. Finally, drug sensitivity responsiveness was assessed in both subtypes. C2 subtype had lower IC50 values for targeted and chemotherapeutic agents (sorafenib, imatinib and methotrexate, etc.). Thus, CMCRGs related subtypes showed poor response to immunotherapy and better responsiveness to targeted agents, and the results might provide a reference for precision treatment of hepatic carcinoma.