Soft matrices downregulate FAK activity to promote growth of tumor-repopulating cells

G9a in Cancer: Mechanisms, Therapeutic Advancements, and Clinical Implications

G9a, also named EHMT2, is a histone 3 lysine 9 (H3K9) methyltransferase responsible for catalyzing H3K9 mono- and dimethylation (H3K9me1 and H3K9me2). G9a contributes to various aspects of embryonic development and tissue differentiation through epigenetic regulation. Furthermore, the aberrant expression of G9a is frequently observed in various tumors, particularly in prostate cancer, where it contributes to cancer pathogenesis and progression. This review highlights the critical role of G9a in multiple cancer-related processes, such as epigenetic dysregulation, tumor suppressor gene silencing, cancer lineage plasticity, hypoxia adaption, and cancer progression. Despite the increased research on G9a in prostate cancer, there are still significant gaps, particularly in understanding its interactions within the tumor microenvironment and its broader epigenetic effects. Furthermore, this review discusses the recent advancements in G9a inhibitors, including the development of dual-target inhibitors that target G9a along with other epigenetic factors such as EZH2 and HDAC. It aims to bring together the existing knowledge, identify gaps in the current research, and suggest future directions for research and treatment strategies.

YAP Inactivation by Soft Mechanotransduction Relieves MAFG for Tumor Cell Dedifferentiation

Solid tumor cells live in a highly dynamic mechanical microenvironment. How the extracellular-matrix-generated mechanotransduction regulates tumor cell development and differentiation remains an enigma. Here, we show that a low mechanical force generated from the soft matrix induces dedifferentiation of moderately stiff tumor cells to soft stem-cell-like cells. Mechanistically, integrin β8 was identified to transduce mechano-signaling to trigger tumor cell dedifferentiation by recruiting RhoGDI1 to inactivate RhoA and subsequently Yes-associated protein (YAP). YAP inactivation relieved the inhibition of v-maf avian musculoaponeurotic fibrosarcoma oncogene homolog G (MAFG), allowing MAFG to transactivate the stemness genes NANOG, SOX2, and NESTIN. Inactivation also restored β8 expression, thereby forming a closed mechanical loop. Importantly, MAFG expression is correlated with worse prognosis. Our findings provide mechanical insights into the regulation of tumor cell dedifferentiation, which has therapeutic implications for exploring innovative strategies to attack malignancies.

Cell response to mechanical microenvironment cues via Rho signaling: From mechanobiology to mechanomedicine

Mechanical cues in the cell microenvironment such as those from extracellular matrix properties, stretching, compression and shear stress, play a critical role in maintaining homeostasis. Upon sensing mechanical stimuli, cells can translate these external forces into intracellular biochemical signals to regulate their cellular behaviors, but the specific mechanisms of mechanotransduction at the molecular level remain elusive. As a subfamily of the Ras superfamily, Rho GTPases have been recognized as key intracellular mechanotransduction mediators that can regulate multiple cell activities such as proliferation, migration and differentiation as well as biological processes such as cytoskeletal dynamics, metabolism, and organ development. However, the upstream mechanosensors for Rho proteins and downstream effectors that respond to Rho signal activation have not been well illustrated. Moreover, Rho-mediated mechanical signals in previous studies are highly context-dependent. In this review, we systematically summarize the types of mechanical cues in the cell microenvironment and provide recent advances on the roles of the Rho-based mechanotransduction in various cell activities, physiological processes and diseases. Comprehensive insights into the mechanical roles of Rho GTPase partners would open a new paradigm of mechanomedicine for a variety of diseases. STATEMENT OF SIGNIFICANCE: In this review, we highlight the critical role of Rho GTPases as signal mediators to respond to physical cues in microenvironment. This article will add a distinct contribution to this set of knowledge by intensively addressing the relationship between Rho signaling and mechanobiology/mechanotransduction/mechanomedcine. This topic has not been discussed by the journal, nor has it yet been developed by the field. The comprehensive picture that will develop, from molecular mechanisms and engineering methods to disease treatment strategies, represents an important and distinct contribution to the field. We hope that this review would help researchers in various fields, especially clinicians, oncologists and bioengineers, who study Rho signal pathway and mechanobiology/mechanotransduction, understand the critical role of Rho GTPase in mechanotransduction.

Synthetic Retinoid Kills Drug-Resistant Cancer Stem Cells via Inducing RARγ-Translocation-Mediated Tension Reduction and Chromatin Decondensation

A recently developed synthetic retinoid abrogates proliferation and induces apoptosis of drug-resistant malignant-cancer-stem-cell-like cells. However, the underlying mechanisms of how the synthetic retinoid induces cancer-stem-cell-like cell tumor-repopulating cell (TRC) apoptosis are elusive. Here, it is shown that although the retinoid and conventional anticancer drugs cisplatin, all-trans retinoic acid, and tazarotene all inhibit cytoskeletal tension and decondense chromatin prior to inducing TRC apoptosis, half-maximal inhibitory concentration of the retinoid is 20-fold lower than those anticancer drugs. The synthetic retinoid induces retinoic acid receptor gamma (RARγ) translocation from the nucleus to the cytoplasm, leading to reduced RARγ binding to Cdc42 promoter and Cdc42 downregulation, which decreases filamentous-actin (F-actin) and inhibits cytoskeletal tension. Elevating F-actin or upregulating histone 3 lysine 9 trimethylation decreases retinoid-induced DNA damage and apoptosis of TRCs. The combinatorial treatment with a chromatin decondensation molecule and the retinoid inhibits tumor metastasis in mice more effectively than the synthetic retinoid alone. These findings suggest a strategy of lowering cell tension and decondensing chromatin to enhance DNA damage to abrogate metastasis of cancer-stem-cell-like cells with high efficacy.

Substrate rigidity dictates colorectal tumorigenic cell stemness and metastasis via CRAD-dependent mechanotransduction

Tumor physical microenvironment contributes greatly to the response of tumor cells. However, the mechanism of how extracellular substrate rigidity remodels colorectal cancer (CRC) cell fate and affects CRC progression remains elusive. Here, we show that F-actin regulator KIAA1211, also known as Capping protein inhibiting regulator of actin dynamics (CRAD), negatively correlates with CRC progression, stemness, and metastasis. Mechanistically, decreased CRAD in soft substrates induces Yes-associated protein (YAP) retention in the cytoplasm, restoring the repression effect on stemness markers NANOG and OCT4, thereby promoting CRC stemness and metastasis. Furthermore, CRAD deficiency promotes colorectal tumor cell softening and regulates epithelial-mesenchymal transition (EMT) states, contributing to its metastasis potential. Clinically, CRAD expression is correlated with malignant degrees and metastasis in CRC patients. Our work uncovers a role of CRAD in anticancer and mechanical signal transduction of the extracellular matrix in CRC.

EHMT1/EHMT2 in EMT, Cancer Stemness and Drug Resistance: Emerging Evidence and Mechanisms

Metastasis, therapy failure and tumor recurrence are major clinical challenges in cancer. The interplay between tumor initiating cells (TICs) and Epithelial-Mesenchymal transition (EMT) drives tumor progression and spread. Recent advances have highlighted the involvement of epigenetic deregulation in these processes. The Euchromatin Histone Lysine Methyltransferase 1 (EHMT1) and Euchromatin Histone Lysine Methyltransferase 2 (EHMT2) that primarily mediate histone 3 lysine 9 di-methylation (H3K9me2), as well as methylation of non-histone proteins, are now recognized to be aberrantly expressed in many cancers. Their deregulated expression is associated with EMT, cellular plasticity and therapy resistance. In this review, we summarize evidence of their myriad roles in cancer metastasis, stemness and drug resistance. We discuss cancer-type specific molecular targets, context-dependent mechanisms and future directions of research in targeting EHMT1/EHMT2 for the treatment of cancer.

Formulation and Evaluation of Isradipine Nanosuspension and Exploring its Role as a Potential Anticancer Drug by Computational Approach

BACKGROUND

T-type calcium channels are aberrantly expressed in different human cancers and regulate cell cycle progression, proliferation, migration, and survival. FAK-1 can promote tumor protein degradation (p53) through ubiquitination, leading to cancer cell growth and proliferation. Similar findings are obtained regarding protease inhibitors' effect on cytokine-induced neutrophil activation that suppresses Granulocyte-macrophage colony-stimulating-factor (GM-CSF) TNF-α-induced O2 release and adherence in human neutrophils without affecting phosphorylation of Extracellular signal-regulated kinase (ERK) and p38. Nanosuspensions are carrier-free, submicron colloidal dispersions which consist of pure drugs and stabilizers. Incorporating drug loaded in nanosuspensions possessed great advantages of passive drug targeting with improved solubility, stability, and bioavailability, as well as lower systemic toxicity.

OBJECTIVE

The present investigation objective was to establish a molecular association of Protease and Focal Adhesion Kinase 1 as cancer targets for isradipine a calcium channel blocker (CCB). Furthermore, the study also aimed to formulate its optimized nanosuspension and how the physical, morphological, and dissolution properties of isradipine impact nanosuspension stability.

MATERIAL AND METHOD

Five different molecular targets, namely Cysteine Proteases (Cathepsin B), Serine Proteases (Matriptase), Aspartate Proteases, Matrix Metalloproteases (MMP), and FAK-1 were obtained from RCSB-PDB, which has some leading associations with the inhibition in cancer pathogenesis. Molecular interactions of these targets with CCB isradipine were identified and established by the molecular simulation docking studies. Isradipine-loaded nanosuspension was prepared by precipitation technique by employing a 23 factorial design. PVP K-30, poloxamer 188, and sodium lauryl sulfate (SLS) were used as polymer, co-polymer, and surfactant. The nanosuspension particles are characterized for particle size, zeta potential, viscosity, polydispersity index (PDI), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), In-vitro drug release kinetics, and short-term stability study.

RESULT

It was found to show considerable interaction with Cysteine, Serine, Aspartate, Threonine, and Matrix metalloproteases with the binding energy of -3.91, -6.7, -3.48, -8.42, respectively. Furthermore, the interaction of isradipine with FAK-1 was compared with 7 native ligands and was found to show significant interaction with a binding energy of -8.62, -7.27, -7.69, -5.67, -5.41, -7.44, -8.21. The optimized nanosuspension was evaluated and exhibited the particle size of 754.9 nm, zeta potential of 32.5 mV, the viscosity of 1.287 cp, and PDI of 1.000. The in-vitro dissolution of the optimized formulation (F8) was higher (96.57%).

CONCLUSION

Isradipine could act as a potential inhibitor of different proteases and FAK-1 associated with tumor growth initiation, progression, and metastasis. Furthermore, isradipine-loaded nanosuspension with optimized release could be utilized to deliver the anticancer drug in a more targeted way as emerging cancer nanotechnology.

Manipulation of the Nanoscale Presentation of Integrin Ligand Produces Cancer Cells with Enhanced Stemness and Robust Tumorigenicity

Developing strategies for efficient expansion of cancer stem-like cells (CSCs) in vitro will help investigate the mechanism underlying tumorigenesis and cancer recurrence. Herein, we report a dynamic culture substrate tethered with integrin ligand-bearing magnetic nanoparticles via a flexible polymeric linker to enable magnetic manipulation of the nanoscale ligand tether mobility. The cancer cells cultured on the substrate with high ligand tether mobility develop into large semispherical colonies with CSCs features, which can be abrogated by magnetically restricting the ligand tether mobility. Mechanistically, the substrate with high ligand tether mobility suppresses integrin-mediated mechanotransduction and histone-related methylation, thereby enhancing cancer cell stemness. The culture-derived high-stemness cells can generate tumors both locally and at the distant lung and uterus much more efficiently than the low-stemness cells. We believe that this magnetic nanoplatform provides a promising strategy for investigating the dynamic interaction between CSCs and the microenvironment and establishing a cost-effective tumor spheroid model.

Modeling the Mechanobiology of Cancer Cell Migration Using 3D Biomimetic Hydrogels

Understanding how cancer cells migrate, and how this migration is affected by the mechanical and chemical composition of the extracellular matrix (ECM) is critical to investigate and possibly interfere with the metastatic process, which is responsible for most cancer-related deaths. In this article we review the state of the art about the use of hydrogel-based three-dimensional (3D) scaffolds as artificial platforms to model the mechanobiology of cancer cell migration. We start by briefly reviewing the concept and composition of the extracellular matrix (ECM) and the materials commonly used to recreate the cancerous ECM. Then we summarize the most relevant knowledge about the mechanobiology of cancer cell migration that has been obtained using 3D hydrogel scaffolds, and relate those discoveries to what has been observed in the clinical management of solid tumors. Finally, we review some recent methodological developments, specifically the use of novel bioprinting techniques and microfluidics to create realistic hydrogel-based models of the cancer ECM, and some of their applications in the context of the study of cancer cell migration.

The roles of nuclear focal adhesion kinase (FAK) on Cancer: a focused review

FAK is a tyrosine kinase overexpressed in cancer cells and plays an important role in the progression of tumors to a malignant phenotype. Except for its typical role as a cytoplasmic kinase downstream of integrin and growth factor receptor signaling, related studies have shown new aspects of the roles of FAK in the nucleus. FAK can promote p53 degradation through ubiquitination, leading to cancer cell growth and proliferation. FAK can also regulate GATA4 and IL-33 expression, resulting in reduced inflammatory responses and immune escape. These findings establish a new model of FAK from the cytoplasm to the nucleus. Activated FAK binds to transcription factors and regulates gene expression. Inactive FAK synergizes with different E3 ligases to promote the turnover of transcription factors by enhancing ubiquitination. In the tumor microenvironment, nuclear FAK can regulate the formation of new blood vessels, affecting the tumor blood supply. This article reviews the roles of nuclear FAK in regulating gene expression. In addition, the use of FAK inhibitors to target nuclear FAK functions will also be emphasized.

Cdc42-dependent modulation of rigidity sensing and cell spreading in tumor repopulating cells

Recently, a robust mechanical method has been established to isolate a small subpopulation of highly tumorigenic tumor repopulating cells (TRCs) from parental melanoma cells. In order to characterize the molecular and mechanical properties of TRCs, we utilized the tension gauge tether (TGT) single-molecule platform and investigated force requirements during early cell spreading events. TRCs required the peak single molecular tension of around 40 pN through integrins for initial adhesion like the parental control cells, but unlike the control cells, they did not spread and formed very few mature focal adhesions (FAs). Single molecule resolution RNA quantification of three Rho GTPases showed that downregulation of Cdc42, but not Rac1, is responsible for the unusual biophysical features of TRCs and that a threshold level of Cdc42 transcripts per unit cell area is required to initiate cell spreading. Cdc42 overexpression rescued TRC spreading through FA formation and restored the sensitivity to tension cues such that TRCs, like parental control cells, increase cell spreading with increasing single-molecular tension cues. Our single molecule studies identified an unusual biophysical feature of suppressed spreading of TRCs that may enable us to distinguish TRC population from a pool of heterogeneous tumor cell population.

Regulation of immune-related diseases by multiple factors of chromatin, exosomes, microparticles, vaccines, oxidative stress, dormancy, protein quality control, inflammation and microenvironment: a meeting report of 2017 International Workshop of the Chinese Academy of Medical Sciences (CAMS) Initiative for Innovative Medicine on Tumor Immunology

Immune cells play key roles in cancer and chronic inflammatory disease. A better understanding of the mechanisms and risks will help develop novel target therapies. At the 2017 International Workshop of the Chinese Academy of Medical Sciences (CAMS) Initiative for Innovative Medicine on Tumor Immunology held in Beijing, China, on May 12, 2017, a number of speakers reported new findings and ongoing studies on immune-related diseases such as cancer, fibrotic disease, diabetes, and others. A considerably insightful overview was provided on cancer immunity, tumor microenvironments, and new immunotherapy for cancer. In addition, chronic inflammatory diseases were discussed. These findings may offer new insights into targeted immunotherapy.