The role of the EGFR signaling pathway in stem cell differentiation during planarian regeneration and homeostasis

Secretion of WNT7A by UC-MSCs assist in promoting the endometrial epithelial regeneration

Stem cell therapy for intrauterine adhesions (IUAs) has been widely used in clinical treatment. However, intravenous injection lacks sufficient targeting capabilities, while in situ injection poses challenges in ensuring the effective survival of stem cells. Furthermore, the mechanism underlying the interaction between stem cells and endometrial cells in vivo remains poorly understood, and there is a lack of suitable in vitro models for studying these problems. Here, we designed an extracellular matrix (ECM)-adhesion mimic hydrogel for intrauterine administration, which was more effective than direct injection in treating IUAs. Additionally, we analyzed the epithelial-mesenchymal transition (EMT) and confirmed that the activation of endometrial epithelial stem cells is pivotal. Our findings demonstrated that umbilical cord mesenchymal stem cells (UC-MSCs) secrete WNT7A to activate endometrial epithelial stem cells, thereby accelerating regeneration of the endometrial epithelium. Concurrently, under transforming growth factor alpha (TGFA) stimulation secreted by the EMT epithelium, UC-MSCs upregulate E-cadherin while partially implanting into the endometrial epithelium.

Quinazolin-4-one/3-cyanopyridin-2-one Hybrids as Dual Inhibitors of EGFR and BRAFV600E: Design, Synthesis, and Antiproliferative Activity

A novel series of hybrid compounds comprising quinazolin-4-one and 3-cyanopyridin-2-one structures has been developed, with dual inhibitory actions on both EGFR and BRAFV600E. These hybrid compounds were tested in vitro against four different cancer cell lines. Compounds 8, 9, 18, and 19 inhibited cell proliferation significantly in the four cancer cells, with GI50 values ranging from 1.20 to 1.80 µM when compared to Doxorubicin (GI50 = 1.10 µM). Within this group of hybrids, compounds 18 and 19 exhibited substantial inhibition of EGFR and BRAFV600E. Molecular docking investigations provided confirmation that compounds 18 and 19 possess the capability to inhibit EGFR and BRAFV600E. Moreover, computational ADMET prediction indicated that most of the newly synthesized hybrids have low toxicity and minimal side effects.

Structure-Activity Relationship Studies Based on Quinazoline Derivatives as EGFR Kinase Inhibitors (2017-Present)

The epidermal growth factor receptor (EGFR) plays a critical role in the tumorigenesis of various forms of cancer. Targeting the mutant forms of EGFR has been identified as an attractive therapeutic approach and led to the approval of three generations of inhibitors. The quinazoline core has emerged as a favorable scaffold for the development of novel EGFR inhibitors due to increased affinity for the active site of EGFR kinase. Currently, there are five first-generation (gefitinib, erlotinib, lapatinib, vandetanib, and icotinib) and two second-generation (afatinib and dacomitinib) quinazoline-based EGFR inhibitors approved for the treatment of various types of cancers. The aim of this review is to outline the structural modulations favorable for the inhibitory activity toward both common mutant (del19 and L858R) and resistance-conferring mutant (T790M and C797S) EGFR forms, and provide an overview of the newly synthesized quinazoline derivatives as potentially competitive, covalent or allosteric inhibitors of EGFR.

Control of cell metabolism by the epidermal growth factor receptor

The epidermal growth factor receptor (EGFR) triggers the activation of many intracellular signals that control cell proliferation, growth, survival, migration, and differentiation. Given its wide expression, EGFR has many functions in development and tissue homeostasis. Some of the cellular outcomes of EGFR signaling involve alterations of specific aspects of cellular metabolism, and alterations of cell metabolism are emerging as driving influences in many physiological and pathophysiological contexts. Here we review the mechanisms by which EGFR regulates cell metabolism, including by modulation of gene expression and protein function leading to control of glucose uptake, glycolysis, biosynthetic pathways branching from glucose metabolism, amino acid metabolism, lipogenesis, and mitochondrial function. We further examine how this regulation of cell metabolism by EGFR may contribute to cell proliferation and differentiation and how EGFR-driven control of metabolism can impact certain diseases and therapy outcomes.

DjPtpn11 is an essential modulator of planarian (Dugesia japonica) regeneration

Freshwater planarian Dugesia japonica is an excellent model organism for investigating stem cell behavior during regeneration. Despite studies showing that numerous genetic factors are involved in regeneration, much more research is required to fully understand the molecular mechanisms that orchestrate regeneration. In this study, we identified an evolutionarily conserved gene DjPtpn11(DjShp2). DjPtpn11 transcripts are expressed in neoblasts and some differentiated cells, with a high expression at the newly formed blastema. Its silencing by RNA interference (RNAi) affected anterior regeneration and inhibited the regeneration of posterior regions, including cholinergic and serotonergic neuron regeneration. In adult planarians, DjPtpn11 knockdown did not affect neoblast survival and proliferation but might prevent the stem cell migration and differentiation through ERK signaling. DjPtpn11 was demonstrated to be necessary for the anterior blastema cell differentiation partially via regulating ERK-DjMkpA activity. DjPtpn11 also influenced posterior specification via DjIslet, suggesting that DjPtpn11 may be involved in regulating the Wnt signaling pathway during the development of posterior blastema. Together, these data identified that DjPtpn11 is an essential modulator for the regeneration of planarians, and it may influence the appropriate differentiation of blastema cells.

Decoding Stem Cells: An Overview on Planarian Stem Cell Heterogeneity and Lineage Progression

Planarians are flatworms capable of whole-body regeneration, able to regrow any missing body part after injury or amputation. The extraordinary regenerative capacity of planarians is based upon the presence in the adult of a large population of somatic pluripotent stem cells. These cells, called neoblasts, offer a unique system to study the process of stem cell specification and differentiation in vivo. In recent years, FACS-based isolation of neoblasts, RNAi functional analyses as well as high-throughput approaches such as single-cell sequencing have allowed a rapid progress in our understanding of many different aspects of neoblast biology. Here, we summarize our current knowledge on the molecular signatures that define planarian neoblasts heterogeneity, which includes a percentage of truly pluripotent stem cells, and guide the commitment of pluripotent neoblasts into lineage-specific progenitor cells, as well as their differentiation into specific planarian cell types.

Synergistic Effect of Curcuma longa Extract in Combination with Phyllanthus niruri Extract in Regulating Annexin A2, Epidermal Growth Factor Receptor, Matrix Metalloproteinases, and Pyruvate Kinase M1/2 Signaling Pathway on Breast Cancer Stem Cell

AIM: This study aimed to investigate the synergistic effects of the combination between Curcuma longa extract (CL) and Phyllanthus niruri extract (PN) in inhibiting optimally the MDA-MB-231 breast cancer stem cells (BCSCs) growth and metastatic by exploring the target and molecular mechanism using integrative bioinformatics approaches and in vitro. METHODS: CL and PN extracts were prepared by maceration method using ethanol 70%. The antiproliferative effect of CL and PN single and combination treatment was examined by 3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2H-tetrazolium bromide assay. The bioinformatic approach was performed to identify molecular targets, key proteins, and molecular mechanism of curcumin and phyllanthin as CL and PN secondary metabolite, respectively, targeted at stemness and migration pathway of BCSCs. RESULTS: The in vitro study showed that CL and PN possess cytotoxic activity in time- and dose-dependent manner. The combination of CL and PN has a synergistic effect by modulating the sensitivity of cells. Using a bioinformatics approach, the annexin A2 (ANXA2), epidermal growth factor receptor (EGFR), matrix metalloproteinases (MMPs), and pyruvate kinase M1/2 (PKM) as potential targets of curcumin and phyllanthin correlated with metastatic inhibition of BC. In addition, molecular docking showed that curcumin and phyllanthin performed similar or better interaction to stemness differentiation regulator pathway particularly histone deacetylase 1, EGFR, Heat Shock Protein 90 Alpha Family Class B Member 1, Hypoxia Inducible Factor 1 Subunit Alpha, and MMP9. CONCLUSION: Combination of CL and PN has potential for the treatment of metastatic BCSCs by targeting ANXA2, EGFR, MMPs, and PKM to resolve stemness and inhibit of BCSCs.

The Act of Controlling Adult Stem Cell Dynamics: Insights from Animal Models

Adult stem cells (ASCs) are the undifferentiated cells that possess self-renewal and differentiation abilities. They are present in all major organ systems of the body and are uniquely reserved there during development for tissue maintenance during homeostasis, injury, and infection. They do so by promptly modulating the dynamics of proliferation, differentiation, survival, and migration. Any imbalance in these processes may result in regeneration failure or developing cancer. Hence, the dynamics of these various behaviors of ASCs need to always be precisely controlled. Several genetic and epigenetic factors have been demonstrated to be involved in tightly regulating the proliferation, differentiation, and self-renewal of ASCs. Understanding these mechanisms is of great importance, given the role of stem cells in regenerative medicine. Investigations on various animal models have played a significant part in enriching our knowledge and giving In Vivo in-sight into such ASCs regulatory mechanisms. In this review, we have discussed the recent In Vivo studies demonstrating the role of various genetic factors in regulating dynamics of different ASCs viz. intestinal stem cells (ISCs), neural stem cells (NSCs), hematopoietic stem cells (HSCs), and epidermal stem cells (Ep-SCs).

Reactive oxygen species rescue regeneration after silencing the MAPK-ERK signaling pathway in Schmidtea mediterranea

Despite extensive research on molecular pathways controlling the process of regeneration in model organisms, little is known about the actual initiation signals necessary to induce regeneration. Recently, the activation of ERK signaling has been shown to be required to initiate regeneration in planarians. However, how ERK signaling is activated remains unknown. Reactive Oxygen Species (ROS) are well-known early signals necessary for regeneration in several models, including planarians. Still, the probable interplay between ROS and MAPK/ERK has not yet been described. Here, by interfering with major mediators (ROS, EGFR and MAPK/ERK), we were able to identify wound-induced ROS, and specifically H₂O₂, as upstream cues in the activation of regeneration. Our data demonstrate new relationships between regeneration-related ROS production and MAPK/ERK activation at the earliest regeneration stages, as well as the involvement of the EGFR-signaling pathway. Our results suggest that (1) ROS and/or H₂O₂ have the potential to rescue regeneration after MEK-inhibition, either by H₂O₂-treatment or light therapy, (2) ROS and/or H₂O₂ are required for the activation of MAPK/ERK signaling pathway, (3) the EGFR pathway can mediate ROS production and the activation of MAPK/ERK during planarian regeneration.

EGFR: An essential receptor tyrosine kinase-regulator of cancer stem cells

The Epidermal Growth Factor Receptor (EGFR) is frequently expressed at elevated levels in different forms of cancer and expression often correlates positively with cancer progression and poor prognosis. Different mutant forms of this protein also contribute to cancer heterogeneity. A constitutively active form of EGFR, EGFRvIII is one of the most important variants. EGFR is responsible for the maintenance and functions of cancer stem cells (CSCs), including stemness, metabolism, immunomodulatory-activity, dormancy and therapy-resistance. EGFR regulates these pathways through several signaling cascades, and often cooperates with other RTKs to exert further control. Inhibitors of EGFR have been extensively studied and display some anticancer efficacy. However, CSCs can also acquire resistance to EGFR inhibitors making effective therapy even more difficult. To ameliorate this limitation of EGFR inhibitors when used as single agents, it may be of value to simultaneously combine multiple EGFR inhibitors or use EGFR inhibitors with regulators of other important cancer phenotype regulating molecules, such as STAT3, or involved in important processes such as DNA repair. These combinatorial approaches require further experimental confirmation, but if successful would expand and improve therapeutic outcomes employing EGFR inhibitors as one arm of the therapy.

Targeting the differentiation of gastric cancer cells (KATO‑III) downregulates epithelial‑mesenchymal and cancer stem cell markers

The aim of the present study was to analyze the acquisition of the differentiated phenotype in the human gastric signet ring cell adenoma cancer KATO-III cell line in vitro. The morphology of KATO-III cells was explored by microcinematography. Different cytokines secreted by both adherent and non-adherent KATO-III cells into medium were observed. The cancer stem cell phenotypes were identified by reverse transcription-quantitative polymerase chain reaction using primers (E-Cad, Slug, Snail, vimentin, NANOG, NESTIN, OCT3/4 and C-X-C motif chemokine receptor 4) or antibodies [cluster of differentiation (CD)90 and CD117] by flow cytometry (FACS). The influence of the induction media for the differentiation of mesenchymal cells was studied through viability and proliferation assays, by evaluating gene expression and the expression of markers via FACS. Cell viability and cell cycle distribution were evaluated following the treatment of KATO-III with acetyl salicylic acid and using the induction media as an inhibitor of epithelial-mesenchymal transition (EMT) and heparanase. A total of 3 phenotypes of KATO-III were observed (adherent, non-adherent and cell cluster), which have internal potential for cell transition into one of the other phenotypes. KATO-III was differentiated into adipocyte-, chondrocyte-, osteocyte- and neurocyte-like cells by the induction media. Identification of the induced cells was conducted using cell dyes. Reduced mRNA expression of EMT-associated molecules, stem cell markers and heparanase was observed with acetyl salicylic acid and induction media. An inhibitory effect of acetyl salicylic acid and the induction media was also noted in regard to cell proliferation. In addition, acetyl salicylic acid induced G0/G1 phase cell cycle arrest in KATO-III cells. In conclusion, the induction of the differentiation of cancer stem cells into non-proliferating cells offers the possibility for novel drug design to overcome the issues associated with metastasis, drug resistance and systemic toxicity with improved therapeutic efficacy.

Copper (II) Ions Activate Ligand-Independent Receptor Tyrosine Kinase (RTK) Signaling Pathway

Receptor tyrosine kinase (RTK) is activated by its natural ligand, mediating multiple essential biological processes. Copper (II) ions are bioactive ions and are crucial in the regulation of cell signaling pathway. However, the crosstalk between copper (II) ions and RTK-mediated cellular signaling remains unclear. Herein, we reported the effect of copper (II) ions on the ligand-independent RTK cellular signaling pathway. Our results indicate that both EGFR and MET signaling were activated by copper (II) in the absence of the corresponding ligands, EGF and HGF, respectively. Consequently, copper (II) ions initiate two RTK-mediated downstream signal transductions, including AKT and ERK. Moreover, copper (II) significantly increased proliferation and cellular migration. Our study proposes a novel role of copper in RTK-mediated signaling for growth factor-independent cancer cell proliferation and migration, implying that targeting both the copper (II) and growth factor in tumor microenvironments may be necessary for cancer treatment.