Integrins linked kinase and focal adhesion kinase as the key signaling mediators of vascular mimicry in metastatic breast tumor cells.

OBJECTIVE: In highly aggressive malignant cancers including breast cancer, vasculogenic mimicry (VM) is the potential of tumor cells to generate a vascular channel network for delivering blood to tumor cells. Detection of genes involved in this process is critical to designing targeted therapy against breast cancer metastasis. In this study, we evaluated the roles of FAK and ILK in the progression of VM in metastatic breast tumor cells. RESULTS: Primary (4T1T), and highly metastatic (4T1B and 4T1L) breast tumor cells were isolated from cancerous mice. The potential of cancer cells to organize themselves into vascular-like structures (VM) has been evaluated with in vitro assessment. The expression of ILK and FAK were examined using real-time polymerase chain reaction. We confirmed the high ability of metastatic tumor cells in vascular-like structure formation. In molecular analysis, our data showed that ILK and FAK expression was significantly elevated in metastatic breast tumor cells. These results indicated that the higher potential of metastatic tumor cells in vascular-like structure formation may be related to higher expression of ILK and FAK. Analysis of molecular features of metastatic tumor cells could be utilized to create a targeted therapeutic strategy against metastasis in breast cancer.

Enzymatic activity of fibroblast activation protein-α is essential for TGF-ß1-induced fibroblastic differentiation of human periodontal ligament cells.

Human periodontal ligament cells (hPDLCs) contain multipotent postnatal stem cells that can differentiate into PDL fibroblasts, osteoblasts, and cementoblasts. Interaction between the extracellular environment and stem cells is an important factor for differentiation into other progenitor cells. To identify cell surface molecules that induce PDL fibroblastic differentiation, we developed a series of monoclonal antibodies against membrane/ECM molecules. One of these antibodies, an anti-PDL25 antibody, recognizes approximately a 100 kDa protein, and this antigenic molecule accumulates in the periodontal ligament region of tooth roots. By mass spectrometric analysis, we found that the antigenic molecule recognized by the anti-PDL25 antibody is fibroblast activation protein α (FAPα). The expression level of FAPα/PDL25 increased in TGF-ß1-induced PDL fibroblasts, and this protein was localized in the cell boundaries and elongated processes of the fibroblastic cells. Ectopic expression of FAPα induced fibroblastic differentiation. In contrast, expression of representative markers for PDL differentiation was decreased by knock down and antibody blocking of FAPα/PDL25. Inhibition of dipeptidyl peptidase activity by a potent FAPα inhibitor dramatically inhibited PDL fibroblastic marker expression but did not affect in cell proliferation and migration.

Extracellular Silica Nanomatrices Promote In Vitro Maturation of Anti-tumor Dendritic Cells via Activation of Focal Adhesion Kinase.

The efficacy of dendritic cell (DC)-based cancer vaccines is critically determined by the functionalities of in vitro maturated DCs. The maturation of DCs typically relies on chemicals that are cytotoxic or hinder the ability of DCs to efficiently activate the antigen-specific cytotoxic T-lymphocytes (CTLs) against tumors. Herein, the maturation chemicals are replaced with extracellular silica nanomatrices, fabricated by glancing angle deposition, to promote in vitro maturation of murine bone marrow-derived DCs (mBMDCs). The extracellular nanomatrices composed of silica nanozigzags (NZs) enable the generation of mature mBMDCs with upregulated levels of co-stimulatory molecules, C-C chemokine receptor type-7, X-C motif chemokine recetpor-1, DC-specific ICAM-3 grabbing nonintegrin, and enhanced endocytic capacity. The in vitro maturation is partially governed by focal adhesion kinase (FAK) that is mechanically activated in the curved cell adhesions formed at the DC-NZ interfaces. The NZ-maturated mBMDCs can prime the antigen-specific CTLs into programmed cell death protein-1 (PD-1)lowCD44high memory phenotypes in vitro and suppress the growth of tumors in vivo. Meanwhile, the NZ-mediated beneficial effects are also observed in human monocyte-derived DCs. This work demonstrates that the silica NZs promote the anti-tumor capacity of in vitro maturated DCs via the mechanoactivation of FAK, supporting the potential of silica NZs being a promising biomaterial for cancer immunotherapy.

Focal adhesion kinase-mediated interaction between tumor and immune cells in the tumor microenvironment: implications for cancer-associated therapies and tumor progression.

Focal adhesion kinase (FAK) expression has been linked to tumor growth, immunosuppression, metastasis, angiogenesis, and therapeutic resistance through kinase-dependent and kinase scaffolding functions in the nucleus and cytoplasm. Hence, targeting FAK alone or with other agents has gained attention as a potential therapeutic strategy. Moreover, mounting evidence shows that FAK activity can influence the tumor immune microenvironment crosstalk to support tumor progression. Recently, tumor immune microenvironment interaction orchestrators have shown to be promising therapeutic agents for cancer immunotherapies. Therefore, this review highlights how FAK regulates the tumor immune microenvironment interplay to promote tumor immune evasive mechanisms and their potential for combination therapies with standard cancer treatments.

Cytoarchitecture of Breast Cancer Cells under Diabetic Conditions: Role of Regulatory Kinases-Rho Kinase and Focal Adhesion Kinase.

Diabetes greatly reduces the survival rates in breast cancer patients due to chemoresistance and metastasis. Reorganization of the cytoskeleton is crucial to cell migration and metastasis. Regulatory cytoskeletal protein kinases such as the Rho kinase (ROCK) and focal adhesion kinase (FAK) play a key role in cell mobility and have been shown to be affected in cancer. It is hypothesized that diabetes/high-glucose conditions alter the cytoskeletal structure and, thus, the elasticity of breast cancer cells through the ROCK and FAK pathway, which can cause rapid metastasis of cancer. The aim of the study was to investigate the role of potential mediators that affect the morphology of cancer cells in diabetes, thus leading to aggressive cancer. Breast cancer cells (MDA-MB-231 and MCF-7) were treated with 5 mM glucose (low glucose) or 25 mM glucose (high glucose) in the presence of Rho kinase inhibitor (Y-27632, 10 mM) or FAK inhibitor (10 mM). Cell morphology and elasticity were monitored using atomic force microscopy (AFM), and actin staining was performed by fluorescence microscopy. For comparative study, normal mammary breast epithelial cells (MCF-10A) were used. It was observed that high-glucose treatments modified the cytoskeleton of the cells, as observed through AFM and fluorescence microscopy, and significantly reduced the elasticity of the cells. Blocking the ROCK or FAK pathway diminished the high-glucose effects. These changes were more evident in the breast cancer cells as compared to the normal cells. This study improves the knowledge on the cytoarchitecture properties of diabetic breast cancer cells and provides potential pathways that can be targeted to prevent such effects.

FOXF1 inhibits invasion and metastasis of lung adenocarcinoma cells and enhances anti-tumor immunity via MFAP4/FAK signal axis.

Based on the joint analysis of multi-omic data and the biological experiments, we demonstrate that FOXF1 inhibits invasion and metastasis of lung adenocarcinoma cells and enhances anti-tumor immunity via regulating MFAP4/FAK signal axis in this study. The levels of FOXF1 and MFAP4 are significantly down-regulated in LUAD, and the increased levels of two genes can improve the clinical prognosis of LUAD patients. Fluorescein reporter gene determination, chromatin immunoprecipitation and gene co-expression analysis indicate that MFAP4 level is positively regulated by transcription factor FOXF1. The function enrichment analysis shows that the levels of FOXF1 and MFAP4 are closely associated with an enrichment of tumor metastasis signatures. FOXF1 can inhibit the migration and invasion of LAUD cells by transcriptionally activating MFAP4 expression. And the overexpression of FOXF1/MFAP4 can reduce focal adhesion kinase (FAK) phosphorylation, while their knockdown result in the opposite effects. The increased levels of FOXF1/MFAP4 enhance the antitumor immunity by increasing the infiltration of dendritic cells and CD4+ T cells, and the interactions between LUAD cells and immune cells, and activating multiple anti-tumor immunity-related pathways. In conclusion, our study reveals the potential function of FOXF1/MFAP4/FAK signal axis in inhibiting metastasis of LUAD cells and modulating anti-tumor immunity of LUAD patients.

LncRNA FAISL Inhibits Calpain 2-Mediated Proteolysis of FAK to Promote Progression and Metastasis of Triple Negative Breast Cancer.

Triple negative breast cancer (TNBC) is the most aggressive subtype in breast tumors. When re-analyzing TCGA breast cancer dataset, we found cell adhesion molecules are highly enriched in differentially expressed genes in TNBC samples, among which Focal Adhesion Kinase (FAK) is most significantly associated with poor survival of TNBC patients. FAK is precisely modulated in the focal adhesion dynamics. To investigate whether lncRNAs regulate FAK signaling, we performed RNA immunoprecipitation sequencing and found FAISL (FAK Interacting and Stabilizing LncRNA) abundantly enriched in FAK-interacting lncRNAs and frequently overexpressed in TCGA TNBC tissues. FAISL promotes TNBC cell adhesion, cytoskeleton spreading, proliferation, and anchor-independent survival. FAISL doesn't affect FAK mRNA but positively regulates FAK protein level by blocking Calpain 2-mediated proteolysis. FAISL interacts with the C-terminus domain of FAK, whereby masks the binding site of Calpain 2 and prevents FAK cleavage. High level of FAISL correlates with FAK expression in tumor tissues and poor prognosis of TNBC patients. A siRNA delivery system targeting FAISL using reduction-responsive nanoparticles effectively inhibits tumor growth and metastasis in TNBC mouse models. Together, these findings uncover a lncRNA-mediated mechanism of regulating FAK proteolysis in the TNBC progression, and highlight the potential of targeting lncRNA FAISL for TNBC treatment.

Acidic preconditioning induced intracellular acid adaptation to protect renal injury via dynamic phosphorylation of focal adhesion kinase-dependent activation of sodium hydrogen exchanger 1.

BACKGROUND: Disruptions in intracellular pH (pHi) homeostasis, causing deviations from the physiological range, can damage renal epithelial cells. However, the existence of an adaptive mechanism to restore pHi to normalcy remains unclear. Early research identified H+ as a critical mediator of ischemic preconditioning (IPC), leading to the concept of acidic preconditioning (AP). This concept proposes that short-term, repetitive acidic stimulation can enhance a cell's capacity to withstand subsequent adverse stress. While AP has demonstrated protective effects in various ischemia-reperfusion (I/R) injury models, its application in kidney injury remains largely unexplored. METHODS: An AP model was established in human kidney (HK2) cells by treating them with an acidic medium for 12 h, followed by a recovery period with a normal medium for 6 h. To induce hypoxia/reoxygenation (H/R) injury, HK2 cells were subjected to hypoxia for 24 h and reoxygenation for 1 h. In vivo, a mouse model of IPC was established by clamping the bilateral renal pedicles for 15 min, followed by reperfusion for 4 days. Conversely, the I/R model involved clamping the bilateral renal pedicles for 35 min and reperfusion for 24 h. Western blotting was employed to evaluate the expression levels of cleaved caspase 3, cleaved caspase 9, NHE1, KIM1, FAK, and NOX4. A pH-sensitive fluorescent probe was used to measure pHi, while a Hemin/CNF microelectrode monitored kidney tissue pH. Immunofluorescence staining was performed to visualize the localization of NHE1, NOX4, and FAK, along with the actin cytoskeleton structure in HK2 cells. Cell adhesion and scratch assays were conducted to assess cell motility. RESULTS: Our findings demonstrated that AP could effectively mitigate H/R injury in HK2 cells. This protective effect and the maintenance of pHi homeostasis by AP involved the upregulation of Na+/H+ exchanger 1 (NHE1) expression and activity. The activity of NHE1 was regulated by dynamic changes in pHi-dependent phosphorylation of Focal Adhesion Kinase (FAK) at Y397. This process was associated with NOX4-mediated reactive oxygen species (ROS) production. Furthermore, AP induced the co-localization of FAK, NOX4, and NHE1 in focal adhesions, promoting cytoskeletal remodeling and enhancing cell adhesion and migration capabilities. CONCLUSIONS: This study provides compelling evidence that AP maintains pHi homeostasis and promotes cytoskeletal remodeling through FAK/NOX4/NHE1 signaling. This signaling pathway ultimately contributes to alleviated H/R injury in HK2 cells.

Immunohistochemistry identifies E-cadherin, N-cadherin and focal adhesion kinase (FAK) as predictors of stage I non-small cell lung carcinoma spread through the air spaces (STAS), and the combinations as prognostic factors.

Background: Spread through air spaces (STAS) is one of the multiple modes of lung cancer dissemination, yet its molecular and clinicopathological characterization remains poorly studied. This study aimed to investigate the effect of adhesion molecule expression levels on the incidence of STAS and postoperative recurrence in stage I lung cancer patients undergoing radical resection. Methods: E-cadherin, P-cadherin, N-cadherin, focal adhesion kinase (FAK), epithelial cell adhesion molecule (EpCAM), neural cell adhesion molecule 1 (NCAM1), vascular cell adhesion molecule 1 (VCAM1), intercellular cell adhesion molecule-1 (ICAM-1) were analyzed retrospectively using immunohistochemistry in patients undergoing radical resection for stage I non-small cell lung cancer (NSCLC). Patients were categorized into four groups based on adhesion molecule expression levels: "low/low", "high/low", "low/high", and "high/high", and the group with the lowest recurrence-free probability (RFP) was defined as high risk. Associations between those adhesion molecules' expression levels and STAS were determined by using the Chi-squared test and logistic regression model. RFP was analyzed by using the log-rank test and Cox proportional risk model. Results: As of January 1, 2024, 12 of 60 patients undergoing radical resection for stage I lung carcinoma had a disease recurrence. All 60 patients' tissue specimens were retrospectively analyzed, and there were no significant differences between patients with STAS-positive (n=30) and STAS-negative (n=30) in baseline clinicopathologic features, except for histological growth patterns. We found that low expression of E-cadherin, high expression of N-cadherin and FAK, and males were independent predictors of higher incidence of STAS. Multivariate Cox analysis showed that tumors with low E-cadherin/high N-cadherin, low E-cadherin/high FAK, and high N-cadherin/high FAK expression were important predictors of recurrence in patients with stage I lung carcinoma. In addition, females and high N-cadherin/high FAK were associated with a high risk of recurrence in patients with STAS. Conclusions: E-cadherin, N-cadherin, and FAK are predictors of STAS occurrence in stage I NSCLC, and their combinations are prognostic factors. The discovery of these molecular markers provides clinicians with a reliable means that may help in the early identification of individuals with a higher risk of recurrence in lung cancer patients, targeting personalized treatment plans such as aggressive adjuvant therapy or closer follow-up.

Specific sialylation of N-glycans and its novel regulatory mechanism.

Altered glycosylation is a common feature of cancer cells. Some subsets of glycans are found to be frequently enriched on the tumor cell surface and implicated in different tumor phenotypes. Among these, changes in sialylation have long been associated with metastatic cell behaviors such as invasion and enhanced cell survival. Sialylation typically exists in three prominent linkages: α2,3, α2,6, and α2,8, catalyzed by a group of sialyltransferases. The aberrant expression of all three linkages has been related to cancer progression. The increased α2,6 sialylation on N-glycans catalyzed by ß-galactoside α2,6 sialyltransferase 1 (ST6Gal1) is frequently observed in many cancers. In contrast, functions of α2,3 sialylation on N-glycans catalyzed by at least three ß-galactoside α2,3-sialyltransferases, ST3Gal3, ST3Gal4, and ST3Gal6 remain elusive due to a possibility of compensating for one another. In this minireview, we briefly describe functions of sialylation and recent findings that different α2,3 sialyltransferases specifically modify target proteins, as well as sialylation regulatory mechanisms vis a complex formation among integrin α3ß1, Golgi phosphoprotein 3 (GOLPH3), phosphatidylinositol 4-kinase IIα (PI4KIIα), focal adhesion kinase (FAK) and sialyltransferase, which suggests a new concept for the regulation of glycosylation in cell biology.

Targeting focal adhesion kinase (FAK) in cancer therapy: A recent update on inhibitors and PROTAC degraders.

Focal adhesion kinase (FAK) is considered as a pivotal intracellular non-receptor tyrosine kinase, and has garnered significant attention as a promising target for anticancer drug development. As of early 2024, a total of 12 drugs targeting FAK have been approved for clinical or preclinical studies worldwide, including three PROTAC degraders. In recent three years (2021-2023), significant progress has been made in designing targeted FAK anticancer agents, including the development of a novel benzenesulfofurazan type NO-releasing FAK inhibitor and the first-in-class dual-target inhibitors simultaneously targeting FAK and HDACs. Given the pivotal role of FAK in the discovery of anticancer drugs, as well as the notable advancements achieved in FAK inhibitors and PROTAC degraders in recent years, this review is underbaked to present a comprehensive overview of the function and structure of FAK. Additionally, the latest findings on the inhibitors and PROTAC degraders of FAK from the past three years, along with their optimization strategies and anticancer activities, were summarized, which might help to provide novel insights for the development of novel targeted FAK agents with promising anticancer potential and favorable pharmacological profiles.

Structural basis for TNIP1 binding to FIP200 during mitophagy.

TNIP1 has been increasingly recognized as a security check to finely adjust the rate of mitophagy by disrupting the recycling of the Unc-51-like kinase complex during autophagosome formation. Through tank-binding kinase 1-mediated phosphorylation of the TNIP1 FIP200 interacting region (FIR) motif, the binding affinity of TNIP1 for FIP200, a component of the Unc-51-like kinase complex, is enhanced, allowing TNIP1 to outcompete autophagy receptors. Consequently, FIP200 is released from the autophagosome, facilitating further autophagosome expansion. However, the molecular basis by which FIP200 utilizes its claw domain to distinguish the phosphorylation status of residues in the TNIP1 FIR motif for recognition is not well understood. Here, we elucidated multiple crystal structures of the complex formed by the FIP200 claw domain and various phosphorylated TNIP1 FIR peptides. Structural and isothermal titration calorimetry analyses identified the crucial residues in the FIP200 claw domain responsible for the specific recognition of phosphorylated TNIP1 FIR peptides. Additionally, utilizing structural comparison and molecular dynamics simulation data, we demonstrated that the C-terminal tail of TNIP1 peptide affected its binding to the FIP200 claw domain. Moreover, the phosphorylation of TNIP1 Ser123 enabled the peptide to effectively compete with the peptide p-CCPG1 (the FIR motif of the autophagy receptor CCPG1) for binding with the FIP200 claw domain. Overall, our work provides a comprehensive understanding of the specific recognition of phosphorylated TNIP1 by the FIP200 claw domain, marking an initial step toward fully understanding the molecular mechanism underlying the TNIP1-dependent inhibition of mitophagy.

Analysis of Expression of the ANG1, CaSR and FAK Proteins in Uterine Fibroids.

Understanding the molecular factors involved in the development of uterine myomas may result in the use of pharmacological drugs instead of aggressive surgical treatment. ANG1, CaSR, and FAK were examined in myoma and peripheral tissue samples taken from women after myoma surgery and in normal uterine muscle tissue samples taken from the control group. Tests were performed using tissue microarray immunohistochemistry. No statistically significant differences in ANG1 expression between the tissue of the myoma, the periphery, and the normal uterine muscle tissue of the control group were recorded. The CaSR value was reduced in the myoma and peripheral tissue and normal in the group of women without myomas. FAK expression was also lower in the myoma and periphery compared to the healthy uterine myometrium. Calcium supplementation could have an effect on stopping the growth of myomas.

Mechanistic insights into mesenchymal-amoeboid transition as an intelligent cellular adaptation in cancer metastasis and resistance.

Malignant cell plasticity is an important hallmark of tumor biology and crucial for metastasis and resistance. Cell plasticity lets cancer cells adapt to and escape the therapeutic strategies, which is the leading cause of cancer patient mortality. Epithelial cells acquire mobility via epithelial-mesenchymal transition (EMT), whereas mesenchymal cells enhance their migratory ability and clonogenic potential by acquiring amoeboid characteristics through mesenchymal-amoeboid transition (MAT). Tumor formation, progression, and metastasis depend on the tumor microenvironment (TME), a complex ecosystem within and around a tumor. Through increased migration and metastasis of cancer cells, the TME also contributes to malignancy. This review underscores the distinction between invasion pattern morphological manifestations and the diverse structures found within the TME. Furthermore, the mechanisms by which amoeboid-associated characteristics promote resistance and metastasis and how these mechanisms may represent therapeutic opportunities are discussed.

Focal adhesion kinase signaling - tumor vulnerabilities and clinical opportunities.

Focal adhesion kinase (FAK; encoded by PTK2) was discovered over 30 years ago as a cytoplasmic protein tyrosine kinase that is localized to cell adhesion sites, where it is activated by integrin receptor binding to extracellular matrix proteins. FAK is ubiquitously expressed and functions as a signaling scaffold for a variety of proteins at adhesions and in the cell cytoplasm, and with transcription factors in the nucleus. FAK expression and intrinsic activity are essential for mouse development, with molecular connections to cell motility, cell survival and gene expression. Notably, elevated FAK tyrosine phosphorylation is common in tumors, including pancreatic and ovarian cancers, where it is associated with decreased survival. Small molecule and orally available FAK inhibitors show on-target inhibition in tumor and stromal cells with effects on chemotherapy resistance, stromal fibrosis and tumor microenvironment immune function. Herein, we discuss recent insights regarding mechanisms of FAK activation and signaling, its roles as a cytoplasmic and nuclear scaffold, and the tumor-intrinsic and -extrinsic effects of FAK inhibitors. We also discuss results from ongoing and advanced clinical trials targeting FAK in low- and high-grade serous ovarian cancers, where FAK acts as a master regulator of drug resistance. Although FAK is not known to be mutationally activated, preventing FAK activity has revealed multiple tumor vulnerabilities that support expanding clinical combinatorial targeting possibilities.

SPP1 promotes tumor progression in esophageal carcinoma by activating focal adhesion pathway.

Background: Recurrence and metastasis are the major obstacles affecting the therapeutic efficacy and clinical outcomes for patients with esophageal carcinoma (ESCA). Secreted phosphoprotein 1 (SPP1) is considered as a hub gene in ESCA and is negatively associated with disease-free survival (DFS) in ESCA. However, the exact roles and underlying mechanisms remain elusive. This study aims to examine the roles of SPP1 on ESCA, and elucidate the potential mechanisms. Methods: Bioinformatics were used to analyze the expression of SPP1 in ESCA tissues, and its relations with clinicopathological characteristics and clinical prognosis in patients with ESCA based on The Cancer Genome Atlas (TCGA) dataset. Loss-of-function was conducted to examine the roles of SPP1 on malignant behaviors of ESCA cells by cell counting kit-8 (CCK8), plate clone, wound healing, and transwell assays. Gene set enrichment analysis (GSEA) was conducted to screen the pathways associated with SPP1 in ESCA. Then, the enriched pathway and the underlying mechanism were elucidated by western blotting, cell adhesion, and cell spreading assays. Lastly, Y15 [a specific inhibitor of focal adhesion kinase (FAK)] was used to examine its potential to inhibit tumor growth in ESCA cells. Results: SPP1 was upregulated in ESCA tissues compared to the adjacent nontumorous tissues, which was closely associated with clinical stage, lymph node metastasis, histological subtype, and p53 mutation. A high expression of SPP1 indicated a poor clinical prognosis in patients with ESCA. The knockdown of SPP1 inhibited cell proliferative, migratory, and invasive capacities in ESCA cells. GSEA indicated that the focal adhesion pathway was closely related with SPP1 in ESCA. Further studies confirmed that the knockdown of SPP1 suppressed cell adhesion ability and reduced the expression of p-FAK and p-Erk in ESCA cells. In addition, Y15 inhibited FAK autophosphorylation and dramatically inhibited cell proliferation, migration, and invasion in ESCA cells. Conclusions: SPP1 promotes tumor progression in ESCA by activating FAK/Erk pathway, and FAK is a potential therapeutic target to overcome tumor recurrence and metastasis of ESCA.

Focal adhesion kinase and its epigenetic interactors as diagnostic and therapeutic hints for pediatric hepatoblastoma.

Background: Hepatoblastoma (HB) is the most common pediatric hepatic malignancy. Despite the progress in HB treatment, investigating HB pathomechanisms to optimize stratification and therapies remains a focal point to improve the outcome for high-risk patients. Methods: Here, we pointed to explore the impact of these mechanisms in HB. An observational study was performed on liver samples from a cohort of 17 patients with a diagnosis of HB and two normal liver samples. The in vitro experiments were executed on the Huh6 human HB cell line treated with the FAK inhibitor TAE226. Results: Our results highlight a significant up-regulation of mRNA and protein expression of FAK in livers from HB with respect to normal livers. The increased protein expression of total and Tyr397 phosphorylated FAK (pTyr397FAK) was significantly correlated with the expression of some epigenetic regulators of histone H3 methylation and acetylation. Of note, the expression of pTyr397FAK, N-methyltransferase enzyme (EZH2) and tri-methylation of the H3K27 residue correlated with tumor size and alpha-fetoprotein (AFP) levels. Finally, TAE226 caused a significant reduction of pTyr397FAK, epigenetic regulators, AFP, EPCAM, OCT4, and SOX2, in association with anti-proliferative and pro-apoptotic effects on HB cells. Conclusion: Our results suggest a role of FAK in HB that requires further investigations mainly focused on the exploration of its effective diagnostic and therapeutic translatability.

Luteolin enhances drug chemosensitivity by downregulating the FAK/PI3K/AKT pathway in paclitaxel­resistant esophageal squamous cell carcinoma.

Drug resistance is a key factor underlying the failure of tumor chemotherapy. It enhances the stem­like cell properties of cancer cells, tumor metastasis and relapse. Luteolin is a natural flavonoid with strong anti­tumor effects. However, the mechanism(s) by which luteolin protects against paclitaxel (PTX)­resistant cancer cell remains to be elucidated. The inhibitory effect of luteolin on the proliferation of EC1/PTX and EC1 cells was detected by cell counting kit­8 assay. Colony formation and flow cytometry assays were used to assess clonogenic capacity, cell cycle and apoptosis. Wound healing and Transwell invasion tests were used to investigate the effects of luteolin on the migration and invasion of EC1/PTX cells. Western blotting was used to detect the protein levels of EMT­related proteins and stem cell markers after sphere formation. Parental cells and drug­resistant cells were screened by high­throughput sequencing to detect the differential expression of RNA and differential genes. ELISA and western blotting were used to verify the screened PI3K/Akt signaling pathway, key proteins of which were explored by molecular docking. Hematoxylin and eosin staining and TUNEL staining were used to observe tumor xenografts on morphology and apoptosis in nude mice. The present study found that luteolin inhibited tumor resistance (inhibited proliferation, induced cell cycle arrest and apoptosis and hindered migration invasion, EMT and stem cell spherification) in vitro in PTX­resistant esophageal squamous cell carcinoma (ESCC) cells. In addition, luteolin enhanced drug sensitivity and promoted the apoptosis of drug­resistant ESCC cells in combination with PTX. Mechanistically, luteolin may inhibit the PI3K/AKT signaling pathway by binding to the active sites of focal adhesion kinase (FAK), Src and AKT. Notably, luteolin lowered the tumorigenic potential of PTX­resistant ESCC cells but did not show significant toxicity in vivo. Luteolin enhanced drug chemosensitivity by downregulating the FAK/PI3K/AKT pathway in PTX­resistant ESCC and could be a promising agent for the treatment of PTX­resistant ESCC cancers.

FAK inhibitors in cancer, a patent review - an update on progress.

INTRODUCTION: Focal adhesion kinase (FAK) is a cytoplasmic non-receptor tyrosine kinase over-expressed in various malignancies which is related to various cellular functions such as adhesion, metastasis and proliferation. AREAS COVERED: There is growing evidence that FAK is a promising therapeutic target for designing inhibitors by regulating the downstream pathways of FAK. Some potential FAK inhibitors have entered clinical phase research. EXPERT OPINION: FAK could be an effective target in medicinal chemistry research and there were a variety of FAKIs have been patented recently. Here, we updated an overview of design, synthesis and structure-activity relationship of chemotherapeutic FAK inhibitors (FAKIs) from 2017 until now based on our previous work. We hope our efforts can broaden the understanding of FAKIs and provide new ideas and insights for future cancer treatment from medicinal chemistry point of view.

Defactinib inhibits FAK phosphorylation and regulates psoriasis via attenuating hyperproliferation of keratinocytes.

Excessive proliferation of keratinocytes is a crucial pathological risk feature of psoriasis. Focal adhesion kinase (FAK) is a non-receptor protein that primarily regulates cell proliferation and migration. However, the expression and regulatory mechanism of FAK in psoriasis remains unclear. This study aimed to investigate the regulation of FAK in psoriasis and examined the potential impact of FAK inhibitor on psoriasis. A small molecular selective FAK inhibitor, defactinib, was used to evaluate the effect of FAK on psoriasis in in vitro and in vivo functional assays. In our experiments, imiquimod (IMQ)-induced psoriasis mice and human keratinocytes cells were used to study the potential roles and mechanisms of FAK in psoriasis. FAK phosphorylation has been weakly detected in normal intact skin and is markedly elevated upon IMQ treatment. By reducing FAK phosphorylation (p-FAK), defactinib treatment could attenuate psoriasiform inflammation and epidermal hyperplasia in IMQ-treated mice compared with IMQ-induced mice treated with the vehicle. In in vitro studies, resiquimod (R848) increased (p-FAK) and promoted cell proliferation in human keratinocytes cells, while defactinib reversed this effect. Mechanistically, defactinib can alleviate the proliferation via JNK/YB1 pathway in vitro and in vivo. Defactinib significantly attenuates psoriasiform inflammation and epidermal hyperproliferation through the inhibition of the FAK-mediated axis. The downregulation of phosphorylated FAK then suppressed the activation of JNK/YB1 protein signaling pathway in psoriasis. Our work highlights targeting FAK as a potentially effective strategy for the treatment of psoriasis.