IRS4 promotes the progression of non-small cell lung cancer and confers resistance to EGFR-TKI through the activation of PI3K/Akt and Ras-MAPK pathways

The effect of IGFBP3 gene knockout by the CRISPR/Cas9 system on the IGF-1 pathway in murine cells

BACKGROUND

The IGF-1 signaling pathway has been deeply involved in the aging mechanism. The insulin-like growth factor binding protein 3 (IGFBP-3) is a protein that binds to IGF-1 that regulates growth, survival, and aging.

OBJECTIVE

The purpose of this study was to investigate the impact of the IGFBP3 gene knockout (KO) on the expressions of aging-related proteins and genes using the CRISPR/Cas9 system.

METHODS

The IGFBP3 gene knockout (KO) was performed by the CRISPR/Cas9 system. Sanger DNA sequencing and Indel analyses were used to verify the induction of mutation.

RESULTS

First, Sanger DNA sequencing was used to analyze the IGFBP3 gene knockout in murine cells (B16F1). The isolation of three colonies with the mutated DNA sequences in the IGFBP3 gene was validated. In addition, the expression levels of the IGFBP3 gene and protein in the edited B16F1 cells were lower than in those of normal B16F1 cells in western blot analysis as well as RT-PCR and qPCR. Moreover, IGFBP3 gene KO cells enhanced the level of SA-ß-gal staining and short telomere length compared to normal B16F1 cells. In particular, it was found that the expression levels of senescence-related proteins such as PI3K, AKT1, PDK1, and p53 were higher in IGFBP3 gene KO cells than in normal cells in both the absence and presence of IGF-1.

CONCLUSIONS

Therefore, the above findings could provide a clue that IGFBP3 could play a key role in the aging mechanism.

OH2 oncolytic virus: A novel approach to glioblastoma intervention through direct targeting of tumor cells and augmentation of anti-tumor immune responses

Glioblastoma (GBM), the deadliest central nervous system cancer, presents a poor prognosis and scant therapeutic options. Our research spotlights OH2, an oncolytic viral therapy derived from herpes simplex virus 2 (HSV-2), which demonstrates substantial antitumor activity and favorable tolerance in GBM. The extraordinary efficacy of OH2 emanates from its unique mechanisms: it selectively targets tumor cells replication, powerfully induces cytotoxic DNA damage stress, and kindles anti-tumor immune responses. Through single-cell RNA sequencing analysis, we discovered that OH2 not only curtails the proliferation of cancer cells and tumor-associated macrophages (TAM)-M2 but also bolsters the infiltration of macrophages, CD4+ and CD8+ T cells. Further investigation into molecular characteristics affecting OH2 sensitivity revealed potential influencers such as TTN, HMCN2 or IRS4 mutations, CDKN2A/B deletion and IDO1 amplification. This study marks the first demonstration of an HSV-2 derived OV's effectiveness against GBM. Significantly, these discoveries have driven the initiation of a phase I/II clinical trial (ClinicalTrials.gov: NCT05235074). This trial is designed to explore the potential of OH2 as a therapeutic option for patients with recurrent central nervous system tumors following surgical intervention.

Altered N6-Methyladenosine Modification Patterns and Transcript Profiles Contributes to Cognitive Dysfunction in High-Fat Induced Diabetic Mice

N6-methyladenosine (m6A) constitutes the paramount post-transcriptional modification within eukaryotic mRNA. This modification is subjected to stimulus-dependent regulation within the central nervous system of mammals, being influenced by sensory experiences, learning processes, and injuries. The patterns of m6A methylation within the hippocampal region of diabetes cognitive impairment (DCI) has not been investigated. A DCI model was established by feeding a high-fat diet to C57BL/6J mice. m6A and RNA sequencing was conducted to profile the m6A-tagged transcripts in the hippocampus. Methylated RNA immunoprecipitation with next-generation sequencing and RNA sequencing analyses yielded differentially m6A-modified and expressed genes in the hippocampus of DCI mice, which were enriched in pathways involving synaptic transmission and axonal guidance. Mechanistic analyses revealed a remarkable change in m6A modification levels through alteration of the mRNA expression of m6A methyltransferases (METTL3 and METTL14) and demethylase (FTO) in the hippocampus of DCI mice. We identified a co-mediated specific RNA regulatory strategy that broadens the epigenetic regulatory mechanism of RNA-induced neurodegenerative disorders associated with metabolic and endocrine diseases.

The strategic involvement of IRS in cancer progression

Insulin Receptor Substrate (IRS), an intracellular molecule devoid of an intrinsic kinase activity, is activated upon binding to IR which thereby works as a scaffold, organizing all signaling complexes and initiating the signaling process downstream. The level of IRS proteins and their stability in the cell is mostly maintained through the phosphorylation status of their tyrosine and serine residues. IRS is positively regulated by phosphorylation of its Tyr residues whereas a Ser residue phosphorylation attenuates it, although there exist some exceptions as well. Other post-translational modifications like O-linked glycosylation, N-linked glycosylation and acetylation also play a prominent role in IRS regulation. Since the discovery of the Warburg effect, people have been curious to find out all possible signaling networks and molecules that could lead to cancer and no doubt, the insulin signaling pathway is identified as one such pathway, which is highly deregulated in cancers. Eminent studies reveal that IRS is a pertinent regulator of cancer and is highly overexpressed in the five most commonly occurring cancers namely- Prostate, Ovarian, Breast, Colon and Lung cancers. IRS1 and IRS2 family members are actively involved in the progression, invasion and metastasis of these cancers. Recently, less studied IRS4 has also emerged as a contributor in ovarian, breast, colorectal and lung cancer, but no such studies related to IRS4 are found in Prostate cancer. The involvement of other IRS family members in cancer is still undiscovered and so paves the way for further exploration. This review is a time-lapse study of IRSs in the context of cancer done over the past two decades and it highlights all the major discoveries made till date, in these cancers from the perspective of IRS.

Is Insulin Receptor Substrate4 (IRS4) a Platform Involved in the Activation of Several Oncogenes?

The IRS (insulin receptor substrate) family of scaffold proteins includes insulin receptor substrate-4 (IRS4), which is expressed only in a few cell lines, including human kidney, brain, liver, and thymus and some cell lines. Its N-terminus carries a phosphotyrosine-binding (PTB) domain and a pleckstrin homology domain (PH), which distinguishes it as a member of this family. In this paper, we collected data about the molecular mechanisms that explain the relevance of IRS4 in the development of cancer and identify IRS4 differences that distinguish it from IRS1 and IRS2. Search engines and different databases, such as PubMed, UniProt, ENSEMBL and SCANSITE 4.0, were used. We used the name of the protein that it encodes "(IRS-4 or IRS4)", or the combination of these terms with the word "(cancer)" or "(human)", for searches. Terms related to specific tumor pathologies ("breast", "ovary", "colon", "lung", "lymphoma", etc.) were also used. Despite the lack of knowledge on IRS4, it has been reported that some cancers and benign tumors are characterized by high levels of IRS-4 expression. Specifically, the role of IRS-4 in different types of digestive tract neoplasms, gynecological tumors, lung cancers, melanomas, hematological tumors, and other less common types of cancers has been shown. IRS4 differs from IRS1 and IRS2 in that can activate several oncogenes that regulate the PI3K/Akt cascade, such as BRK and FER, which are characterized by tyrosine kinase-like activity without regulation via extracellular ligands. In addition, IRS4 can activate the CRKL oncogene, which is an adapter protein that regulates the MAP kinase cascade. Knowledge of the role played by IRS4 in cancers at the molecular level, specifically as a platform for oncogenes, may enable the identification and validation of new therapeutic targets.

Competition for cysteine acylation by C16:0 and C18:0 derived lipids is a global phenomenon in the proteome

S-acylation is a reversible posttranslational protein modification consisting of attachment of a fatty acid to a cysteine via a thioester bond. Research over the last few years has shown that a variety of different fatty acids, such as palmitic acid (C16:0), stearate (C18:0), or oleate (C18:1), are used in cells to S-acylate proteins. We recently showed that GNAI proteins can be acylated on a single residue, Cys3, with either C16:0 or C18:1, and that the relative proportion of acylation with these fatty acids depends on the level of the respective fatty acid in the cell's environment. This has functional consequences for GNAI proteins, with the identity of the acylating fatty acid affecting the subcellular localization of GNAIs. Unclear is whether this competitive acylation is specific to GNAI proteins or a more general phenomenon in the proteome. We perform here a proteome screen to identify proteins acylated with different fatty acids. We identify 218 proteins acylated with C16:0 and 308 proteins acylated with C18-lipids, thereby uncovering novel targets of acylation. We find that most proteins that can be acylated by C16:0 can also be acylated with C18-fatty acids. For proteins with more than one acylation site, we find that this competitive acylation occurs on each individual cysteine residue. This raises the possibility that the function of many different proteins can be regulated by the lipid environment via differential S-acylation.

Trends in insulin resistance: insights into mechanisms and therapeutic strategy

The centenary of insulin discovery represents an important opportunity to transform diabetes from a fatal diagnosis into a medically manageable chronic condition. Insulin is a key peptide hormone and mediates the systemic glucose metabolism in different tissues. Insulin resistance (IR) is a disordered biological response for insulin stimulation through the disruption of different molecular pathways in target tissues. Acquired conditions and genetic factors have been implicated in IR. Recent genetic and biochemical studies suggest that the dysregulated metabolic mediators released by adipose tissue including adipokines, cytokines, chemokines, excess lipids and toxic lipid metabolites promote IR in other tissues. IR is associated with several groups of abnormal syndromes that include obesity, diabetes, metabolic dysfunction-associated fatty liver disease (MAFLD), cardiovascular disease, polycystic ovary syndrome (PCOS), and other abnormalities. Although no medication is specifically approved to treat IR, we summarized the lifestyle changes and pharmacological medications that have been used as efficient intervention to improve insulin sensitivity. Ultimately, the systematic discussion of complex mechanism will help to identify potential new targets and treat the closely associated metabolic syndrome of IR.

Sensitization of Non-Small Cell Lung Cancer Cells to Gefitinib and Reversal of Epithelial-Mesenchymal Transition by Aloe-Emodin Via PI3K/Akt/TWIS1 Signal Blockage

Objective

To explore the impacts of AE (aloe-emodin) in gefitinib-resistant NSCLC (non-small cell lung cancer) cells and the corresponding mechanism.

Methods

PC9 and PC9-GR cells were cultured and treated by gefitinib, AE, or the combination of the two drugs. Then, viability, apoptosis, migration and invasion of cells were investigated using CCK-8, TUNEL, wound healing assay, and transwell assay, respectively. Female BALB/c nude mice were employed for the establishment of xenograft tumor models to examine the role of AE in tumor growth.

Results

PC9-GR cells showed reduced apoptosis and enhanced cell viability, migration and invasion upon treatment by gefitinib, compared with PC9 cells. E-cahherin in PC9-GR cells was down-regulated, while Vimentin, Snail2 (or Slug) and Twist1 in PC9-GR cells were up-regulated, compared with PC9 cells. Meanwhile, treatment by a combination of gefitinib and AE significantly strengthened apoptosis of PC9-GR cells, while attenuated their migration and invasion, compared with the control group or treatment by gefitinib or AE alone. WB results showed that AE could reverse EMT and activation of PI3K/AKT signalling pathway in PC9-GR cells. In vivo experiments showed that tumor growth and EMT of PC9-GR cells were dramatically repressed after treatment by a combination of AE and gefitinib. Additionally, the use of SC97 (a PI3K/Akt pathway activator) could counteract the effects of AE in gefitinib-resistant PC9 cells.

Conclusions

AE could enhance the gefitinib sensitivity of PC9-GR cells and reverse EMT by blocking PI3K/Akt/TWIS1 signal pathway.

Patients with Invasive Lobular Carcinoma Show a Significant Increase in IRS-4 Expression Compared to Infiltrative Ductal Carcinoma—A Histopathological Study

Background and Objectives: Breast cancer (BC) is the first diagnosed type of cancer and the second leading cause of cancer-related mortality in women. In addition, despite the improvement in treatment and survival in these patients, the global prevalence and incidence of this cancer are rising, and its mortality may be different according to the histological subtype. Invasive lobular carcinoma (ILC) is less common but entails a poorer prognosis than infiltrative ductal carcinoma (IDC), exhibiting a different clinical and histopathological profile. Deepening study on the molecular profile of both types of cancer may be of great aid to understand the carcinogenesis and progression of BC. In this sense, the aim of the present study was to explore the histological expression of Insulin receptor substrate 4 (IRS-4), cyclooxygenase 2 (COX-2), Cyclin D1 and retinoblastoma protein 1 (Rb1) in patients with ILC and IDC. Patients and Methods: Thus, breast tissue samples from 45 patients with ILC and from 45 subjects with IDC were analyzed in our study. Results: Interestingly, we observed that IRS-4, COX-2, Rb1 and Cyclin D1 were overexpressed in patients with ILC in comparison to IDC. Conclusions: These results may indicate a differential molecular profile between both types of tumors, which may explain the clinical differences among ILC and IDC. Further studies are warranted in order to shed light onto the molecular and translational implications of these components, also aiding to develop a possible targeted therapy to improve the clinical management of these patients.

Actinomycin D Arrests Cell Cycle of Hepatocellular Carcinoma Cell Lines and Induces p53-Dependent Cell Death: A Study of the Molecular Mechanism Involved in the Protective Effect of IRS-4

Actinomycin D (ActD) is an FDA-approved NCI oncology drug that specifically targets and downregulates stem cell transcription factors, which leads to a depletion of stem cells within the tumor bulk. Recently, our research group demonstrated the importance of IRS-4 in the development of liver cancer. In this study, we evaluated the protective effects of IRS-4 against ActD. For this study, three hepatocellular carcinoma cell lines (HepG2, Huh7, and Chang cells) were used to study the mechanism of actinomycin D. Most assays were carried out in the Hep G2 cell line, due to the high expression of stem cell biomarkers. We found that ActD caused HepG2 cell necroptosis characterized by DNA fragmentation, decreased mitochondrial membrane potential, cytochrome c depletion, and decreased the levels of reduced glutathione. However, we did not observe a clear increase in apoptosis markers such as annexin V presence, caspase 3 activation, or PARP fragmentation. ActD produced an activation of MAP kinases (ERK, p38, and JNK) and AKT. ActD-induced activation of AKT and MAP kinases produced an activation of the Rb-E2F cascade together with a blockage of cell cycle transitions, due to c-jun depletion. ActD led to the inhibition of pCdK1 and pH3 along with DNA fragmentation resulting in cell cycle arrest and the subsequent activation of p53-dependent cell death in the HepG2 cell line. Only JNK and AKT inhibitors were protective against the effects of ActD. N-Acetyl-L-cysteine also had a protective effect as it restored GSH levels. A likely mechanism for this is IRS-4 stimulating GCL-GSH and inhibiting the Brk-CHK1-p53 pathway. The assessment of the IRS-4 in cancer biopsies could be of interest to carry out a personalized treatment with ActD.

Possible Role of IRS-4 in the Origin of Multifocal Hepatocellular Carcinoma

Simple Summary

Hepatocellular carcinoma (HCC) is a potentially deadly liver cancer with a high prevalence worldwide. Despite the very efforts placed on this cancer, most cases are associated with poor prognosis and the understanding of the molecular mechanisms implicated in the development of HCC are arising as a potential therapeutic approach of this cancer. In this sense, we aimed to evaluate the established role of insulin receptor substrate 4 (IRS-4) in the tumorigenesis and progression of HCC. Thus, we leaded a histopathological study of this component, along with additional cancer biomarkers such as PCNA, Ki67, and pH3. In addition, in vitro models of different cell lines were used to describe the effects of IRS-4 overexpression/silencing. Finally, immunoblot analysis and transfection experiments were also conducted. Our research demonstrates that IRS-4 is involved in multiple tumoral effects such as proliferation, cell migration, and cell-collagen adhesion as well as the appearance of multifocal HCC.

Abstract

New evidence suggests that insulin receptor substrate 4 (IRS-4) may play an important role in the promotion of tumoral growth. In this investigation, we have evaluated the role of IRS-4 in a pilot study performed on patients with liver cancer. We used immunohistochemistry to examine IRS-4 expression in biopsies of tumoral tissue from a cohort of 31 patient suffering of hepatocellular carcinoma (HCC). We simultaneously analyzed the expression of the cancer biomarkers PCNA, Ki-67, and pH3 in the same tissue samples. The in vitro analysis was conducted by studying the behavior of HepG2 cells following IRS-4 overexpression/silencing. IRS-4 was expressed mainly in the nuclei of tumoral cells from HCC patients. In contrast, in healthy cells involved in portal triads, canaliculi, and parenchymal tissue, IRS-4 was observed in the cytosol and the membrane. Nuclear IRS-4 in the tumoral region was found in 69.9 ± 3.2%, whereas in the surrounding healthy hepatocytes, nuclear IRS-4 was rarely observed. The percentage of tumoral cells that exhibited nuclear PCNA and Ki-67 were 52.1 ± 7%, 6.1 ± 1.1% and 1.3 ± 0.2%, respectively. Furthermore, we observed a significant positive linear correlation between nuclear IRS-4 and PCNA (r = 0.989; p < 0.001). However, when we correlated the nuclear expression of IRS-4 and Ki-67, we observed a significant positive curvilinear correlation (r = 0.758; p < 0.010). This allowed us to define two populations, (IRS-4 + Ki-67 ≤ 69%) and (IRS-4 + Ki-67 > 70%). The population with lower levels of IRS-4 and Ki-67 had a higher risk of suffering from multifocal liver cancer (OR = 16.66; CI = 1.68–164.8 (95%); p < 0.05). Immunoblot analyses showed that IRS-4 in normal human liver biopsies was lower than in HepG2, Huh7, and Chang cells. Treatment of HepG2 with IGF-1 and EGF induced IRS-4 translocation to the nucleus. Regulation of IRS-4 levels via HepG2 transfection experiments revealed the protein’s role in proliferation, cell migration, and cell-collagen adhesion. Nuclear IRS-4 is increased in the tumoral region of HCC. IRS-4 and Ki-67 levels are significantly correlated with the presence of multifocal HCC. Moreover, upregulation of IRS-4 in HepG2 cells induced proliferation by a β-catenin/Rb/cyclin D mechanism, whereas downregulation of IRS-4 caused a loss in cellular polarity and in its adherence to collagen as well as a gain in migratory and invasive capacities, probably via an integrin α2 and focal adhesion cascade (FAK) mechanism.