FAK association with multiple signal proteins mediates pressure-induced colon cancer cell adhesion via a Src-dependent PI3K/Akt pathway

A novel FAK-degrading PROTAC molecule exhibited both anti-tumor activities and efficient MDR reversal effects

FAK (focal adhesion kinase) is widely involved in cancer growth and drug resistance development. Thus, FAK inhibition has emerged as an effective strategy for tumor treatment both as a monotherapy or in combination with other treatments. But the current FAK inhibitors mainly concentrate on its kinase activity, overlooking the potential significance of FAK scaffold proteins. In this study we employed the PROTAC technology, and designed a novel PROTAC molecule F2 targeting FAK based on the FAK inhibitor IN10018. F2 exhibited potent inhibitory activities against 4T1, MDA-MB-231, MDA-MB-468 and MDA-MB-435 cells with IC50 values of 0.73, 1.09, 5.84 and 3.05 μM, respectively. On the other hand, F2 also remarkably reversed the multidrug resistance (MDR) in HCT8/T, A549/T and MCF-7/ADR cells. Both the effects of F2 were stronger than the FAK inhibitor IN10018. To our knowledge, F2 was the first reported FAK-targeted PROTAC molecule exhibiting reversing effects on chemotherapeutic drug resistance, and its highest reversal fold could reach 158 times. The anti-tumor and MDR-reversing effects of F2 might be based on its inhibition on AKT (protein kinase B, PKB) and ERK (extracellular signal-regulated kinase) signaling pathways, as well as its impact on EMT (epithelial-mesenchymal transition). Furthermore, we found that F2 could reduce the protein level of P-gp in HCT8/T cells, thereby contributing to reverse drug resistance from another perspective. Our results will boost confidence in future research focusing on targeting FAK and encourage further investigation of PROTAC with potent in vivo effects.

TRIM72 inhibits cell migration and epithelial-mesenchymal transition by attenuating FAK/akt signaling in colorectal cancer

TRIM72 (MG53), a membrane repair protein with E3-ligase activity, plays a crucial role in colorectal cancer (CRC). This study examined TRIM72 expression in primary CRC tumors and paired liver metastases using RT-PCR. Findings revealed significantly lower TRIM72 levels in liver metastases compared to primary tumors (p < 0.001). Aberrant TRIM72 expression correlated with lymph node metastasis and advanced clinical stages. Overexpression of TRIM72 inhibited CRC cell migration, intravasation, and EMT in vitro and in vivo, while TRIM72 knockout increased migration and invasion. TRIM72 interacted with Focal Adhesion Kinase (FAK), implicating the FAK/Akt signaling axis in colon cancer spread. Lower TRIM72 levels were associated with reduced survival rates, highlighting its potential as a prognostic marker and therapeutic target in CRC.

Development of novel focal adhesion kinase (FAK) inhibitors for targeting cancer: Structural insights and therapeutic potential

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase frequently overexpressed in various cancer cells, facilitating tumor growth through the regulation of cell adhesion, migration, and proliferation. Consequently, targeting FAK is considered a promising anti-tumor strategy, particularly for invasive cancers. Numerous potent small-molecule inhibitors have progressed to clinical trials. Among these, Defactinib is under evaluation for regulatory approval as a treatment for ovarian serous tumors. Furthermore, novel FAK inhibitors, including PROTACs, have emerged as key research focuses, anticipated to overcome the limitations of traditional inhibitors. In this Perspective, we highlight the protein structure, biological functions, relevant signaling pathways, and associations of FAK with cancer development. We also analyze the clinical status of FAK inhibitors, paying special attention to the various classes of FAK inhibitors, with detailed analyses of their chemical structures, structure-activity relationships (SARs), bioactivity profiles, selectivity profiles, and therapeutic potentials.

Targeting focal adhesion kinase (FAK) for cancer therapy: FAK inhibitors, FAK-based dual-target inhibitors and PROTAC degraders

Focal adhesion kinase (FAK), a non-receptor tyrosine kinase, plays an essential role in regulating cell proliferation, migration and invasion through both kinase-dependent enzymatic function and kinase-independent scaffolding function. The overexpression and activation of FAK is commonly observed in various cancers and some drug-resistant settings. Therefore, targeted disruption of FAK has been identified as an attractive strategy for cancer treatment. To date, numerous structurally diverse inhibitors targeting distinct domains of FAK have been developed, encompassing kinase domain inhibitors, FERM domain inhibitors, and FAT domain inhibitors, with several FAK inhibitors advanced to clinical trials. Moreover, given the critical role of FAK scaffolding function in signal transduction, FAK-targeted PROTACs have also been developed. Although no current FAK-targeted therapeutics have been approved for the market, the combination of FAK inhibitors with other anticancer drugs has shown considerable promise in the clinic. This review provides an overview of current drug discovery strategies targeting FAK, including the development of FAK inhibitors, FAK-based dual-target inhibitors and proteolysis-targeting chimeras (PROTACs) in both literature and patent applications. Accordingly, their design and optimization process, mechanisms of action and biological activities are discussed to offer insights into future directions of FAK-targeting drug discovery in cancer therapy.

Role of c-Src in Carcinogenesis and Drug Resistance

The aberrant transformation of normal cells into cancer cells, known as carcinogenesis, is a complex process involving numerous genetic and molecular alterations in response to innate and environmental stimuli. The Src family kinases (SFK) are key components of signaling pathways implicated in carcinogenesis, with c-Src and its oncogenic counterpart v-Src often playing a significant role. The discovery of c-Src represents a compelling narrative highlighting groundbreaking discoveries and valuable insights into the molecular mechanisms underlying carcinogenesis. Upon oncogenic activation, c-Src activates multiple downstream signaling pathways, including the PI3K-AKT pathway, the Ras-MAPK pathway, the JAK-STAT3 pathway, and the FAK/Paxillin pathway, which are important for cell proliferation, survival, migration, invasion, metastasis, and drug resistance. In this review, we delve into the discovery of c-Src and v-Src, the structure of c-Src, and the molecular mechanisms that activate c-Src. We also focus on the various signaling pathways that c-Src employs to promote oncogenesis and resistance to chemotherapy drugs as well as molecularly targeted agents.

SKAP2-A Molecule at the Crossroads for Integrin Signalling and Immune Cell Migration and Function

Src-kinase associated protein 2 (SKAP2) is an intracellular scaffolding protein that is broadly expressed in immune cells and is involved in various downstream signalling pathways, including, but not limited to, integrin signalling. SKAP2 has a wide range of binding partners and fine-tunes the rearrangement of the cytoskeleton, thereby regulating cell migration and immune cell function. Mutations in SKAP2 have been associated with several inflammatory disorders such as Type 1 Diabetes and Crohn's disease. Rodent studies showed that SKAP2 deficient immune cells have diminished pathogen clearance due to impaired ROS production and/or phagocytosis. However, there is currently no in-depth understanding of the functioning of SKAP2. Nevertheless, this review summarises the existing knowledge with a focus of its role in signalling cascades involved in cell migration, tissue infiltration and immune cell function.

A novel drug-like water-soluble small molecule Focal Adhesion Kinase (FAK) activator promotes intestinal mucosal healing

Non-steroidal anti-inflammatory drugs (NSAIDs) injure the proximal and distal gut by different mechanisms. While many drugs reduce gastrointestinal injury, no drug directly stimulates mucosal wound healing. Focal adhesion kinase (FAK), a non-receptor tyrosine kinase, induces epithelial sheet migration. We synthesized and evaluated a water-soluble FAK-activating small molecule, M64HCl, with drug-like properties. Monolayer wound closure and Western blots measured migration and FAK phosphorylation in Caco-2 ​cells, in vitro kinase assays established FAK activation, and pharmacologic tests assessed drug-like properties. 30 ​mg/kg/day M64HCl was administered in two murine small intestine injury models for 4 days. M64HCl (0.1-1000 ​nM) dose-dependently increased Caco-2 FAK-Tyr 397 phosphorylation, without activating Pyk2 and accelerated Caco-2 monolayer wound closure. M64HCl dose-responsively activates the FAK kinase domain vs. the non-salt M64, increasing the Vmax of ATP-binding. Pharmacologic tests suggested M64HCl has drug-like properties and is enterally absorbed. M64HCl 25 ​mg/kg/day continuous infusion promoted healing of ischemic jejunal ulcers and indomethacin-induced small intestinal injury in C57Bl/6 mice. M64HCl-treated mice exhibited smaller ulcers 4 days after ischemic ulcer induction or indomethacin injury. Renal histology and plasma creatinine were normal. Mild hepatic inflammatory changes and ALT elevation were similar among M64HCl-treated mice and controls. M64HCl was concentrated in kidney and gastrointestinal mucosa and functional nephrectomy studies suggested predominantly urinary excretion. Little toxicity was observed in vitro or in single-dose mouse toxicity studies until >1000x higher than effective concentrations. M64HCl, a water-soluble FAK activator, promotes epithelial restitution and intestinal mucosal healing and may be useful to treat gut mucosal injury.

ATP Promotes Oral Squamous Cell Carcinoma Cell Invasion and Migration by Activating the PI3K/AKT Pathway via the P2Y2-Src-EGFR Axis

Oral cancer is one of the most common malignancies of the head and neck, and approximately 90% of oral cancers are oral squamous cell carcinomas (OSCCs). The purinergic P2Y2 receptor is upregulated in breast cancer, pancreatic cancer, colorectal cancer, and liver cancer, but its role in OSCC is still unclear. Here, we examined the effects of P2Y2 on the invasion and migration of oral cancer cells (SCC15 and CAL27). The BALB/c mouse model was used to observe the involvement of P2Y2 with tumors in vivo. P2Y2, Src, and EGFR are highly expressed in OSCC tissues and cell lines. Stimulation with ATP significantly enhanced cell invasion and migration in oral cancer cells, and enhanced the activity of Src and EGFR protein kinases, which is mediated by the PI3K/AKT signaling pathway. P2Y2 knockdown attenuated the above ATP-driven events in vitro and in vivo. The PI3K/AKT signaling pathway was blocked by Src or EGFR inhibitor. Extracellular ATP activates the PI3K/AKT pathway through the P2Y2-Src-EGFR axis to promote OSCC invasion and migration, and thus, P2Y2 may be a potential novel target for antimetastasis therapy.

PLEKHH2 binds β-arrestin1 through its FERM domain, activates FAK/PI3K/AKT phosphorylation, and promotes the malignant phenotype of non-small cell lung cancer

PLEKHH2 is an important FERM domain containing-protein. However, the role of PLEKHH2 in human solid tumors has not been reported yet. We report that PLEKHH2 showed enhanced cytoplasmic expression in non-small cell lung cancer (NSCLC). Its overexpression was positively correlated with high TNM stage, low differentiation, lymphatic node metastasis, and poor prognosis. In A549 and H1299 cells, high expression of PLEKHH2 significantly promoted cell proliferation, migration, invasion, and increased the expression of proliferation- and invasion-related proteins. It also enhanced the phosphorylation of FAK and promoted the activity of the PI3K/AKT pathway. Immunofluorescence and co-immunoprecipitation analyses were performed to elucidate the molecular mechanism underlying PLEKHH2-mediated regulation of proliferation and invasion in lung cancer cells. Upon transfection of full length PLEKHH2 or its FERM domain, we observed enhanced binding of PLEKHH2 to β-arrestin1, whereas FAK- β-arrestin1 binding was diminished and this led to an increase in FAK phosphorylation. PLEKHH2-mutant plasmids without the FERM domain could not effectively promote its binding to β-arrestin1, activation of FAK phosphorylation, PI3K/AKT activation, or the malignant phenotype. Our findings suggested that PLEKHH2 is an important oncogene in NSCLC. PLEKHH2 binding to β-arrestin1 through the FERM domain competitively inhibits β-arrestin1 binding to FAK, which causes the dissociation of FAK from the FAK-β-arrestin1 complex. Furthermore, the dissociation of FAK promotes its autophosphorylation, activates the PI3K/AKT signaling pathway, and subsequently promotes lung cancer cell proliferation, migration, and invasion. These results provide evidence for the potential use of PLEKHH2 inhibition as an anticancer therapy.

Calcium fructoborate regulate colon cancer (Caco-2) cytotoxicity through modulation of apoptosis

Sugar-borate esters have recently been reported to have anti-cancer potential. Among the sugar-borate esters, calcium fructoborate (CaFB) possesses beneficial effects on human health. Despite the beneficial effects of CaFB, there is a lack of knowledge about their mode of action in cancer. The potential cytotoxic effects of CaFB were investigated on colon cancer cells (Caco-2). The mode of action was determined through the evaluation of Fyn and Hck expression levels together with Bcl-2, Bax, and PI3K/Akt pathway proteins. CaFB treatment was found to be most effective on Caco-2 cells at 10 mM concentration for 24 h. Decreased Bcl-2 levels and increased Bax levels at 10 mM were evaluated as an indicator of apoptotic effects of CaFB. Akt, p70S6K, and 4EBP1 levels, in general, tend to decrease following CaFB, while PTEN and TSC2 levels have been found to increase. Furthermore, CaFB upregulated Hck expression and downregulated Fyn expression. In conclusion, our results indicated that CaFB treatment at 10 mM concentration, the IC50 dose found in our study, might prevent colon cancer cell proliferation both by inducing apoptosis and presumably by activating autophagy.

Repurposing Tranexamic Acid as an Anticancer Agent

Tranexamic Acid (TA) is a clinically used antifibrinolytic agent that acts as a Lys mimetic to block binding of Plasminogen with Plasminogen activators, preventing conversion of Plasminogen to its proteolytically activated form, Plasmin. Previous studies suggested that TA may exhibit anticancer activity by blockade of extracellular Plasmin formation. Plasmin-mediated cleavage of the CDCP1 protein may increase its oncogenic functions through several downstream pathways. Results presented herein demonstrate that TA blocks Plasmin-mediated excision of the extracellular domain of the oncoprotein CDCP1. In vitro studies indicate that TA reduces the viability of a broad array of human and murine cancer cell lines, and breast tumor growth studies demonstrate that TA reduces cancer growth in vivo. Based on the ability of TA to mimic Lys and Arg, we hypothesized that TA may perturb multiple processes that involve Lys/Arg-rich protein sequences, and that TA may alter intracellular signaling pathways in addition to blocking extracellular Plasmin production. Indeed, TA-mediated suppression of tumor cell viability is associated with multiple biochemical actions, including inhibition of protein synthesis, reduced activating phosphorylation of STAT3 and S6K1, decreased expression of the MYC oncoprotein, and suppression of Lys acetylation. Further, TA inhibited uptake of Lys and Arg by cancer cells. These findings suggest that TA or TA analogs may serve as lead compounds and inspire the production of new classes of anticancer agents that function by mimicking Lys and Arg.

Overexpression of pressure-responsive miRNA-5703 inhibits pressure-induced growth and metastasis of liver cancer

A vast majority of liver cancers coexist with cirrhosis and/or portal hypertension. A high-pressure tumour microenvironment may lead to malignant progression of liver cancer. Through quantitative reverse transcription-polymerase chain reaction, we found that miRNA-5703 was expressed at low levels in HepG2 and Huh-7 cells and pressure-treated MHCC97H implanted mouse cancer tissues, while its potential target gene, sarcoma gene (SRC), was highly expressed. The expression of miRNA-5703 was higher in liver cancer tissues from Barcelona Clinic Liver Cancer (BCLC) stage A1 patients than those from BCLC stage A2-D patients, whereas SRC showed the opposite expression pattern. Bioinformatics analysis, luciferase reporter assay, and western blotting were performed to verify the relationship between miRNA-5703 and its potential target SRC. Using intravital imaging and immunohistochemistry, we demonstrated that pressure promotes tumour growth in subcutaneous tumourigenesis nude mice, and overexpression of miRNA-5703 significantly downregulated Ki67 and upregulated NM23 in tumour tissues of mice, implying the blockage of tumour growth and metastasis. The activation of proliferation, migration, and invasion of HepG2 and Huh-7 cells by pressure, and inhibition by overexpressing miRNA-5703 were observed by cell counting kit-8 assay, flow cycle assay, transwell assay, and wound healing assay. After the intervention of pressure, inhibitor, and lentivirus to hepatoma cells, SRC, focal adhesion kinase (FAK), phosphatidylinositol 3-kinase (PI3K), serum/glucocorticoid regulated kinase-3 (SGK3), phosphoinositide dependent protein kinase 1 (PDK1), and paxillin were upregulated, and forkhead box O1 (FOXO1) and cyclin dependent kinase inhibitor 1B (P27^Kip1) were downregulated in pressure-loaded hepatoma cells, which could be reversed by overexpression of miRNA-5703 or SRC knockdown. In conclusion, upregulation of miRNA-5703 inhibited pressure-induced growth and metastasis by suppressing the SRC-FAK-FOXO1 axis and SRC-paxillin axis. This novel perspective may be conducive to the mechano-inspired anticancer drugs of liver cancer.

The 'Yin and Yang' of Cancer Cell Growth and Mechanosensing

In cancer, two unique and seemingly contradictory behaviors are evident: on the one hand, tumors are typically stiffer than the tissues in which they grow, and this high stiffness promotes their malignant progression; on the other hand, cancer cells are anchorage-independent-namely, they can survive and grow in soft environments that do not support cell attachment. How can these two features be consolidated? Recent findings on the mechanisms by which cells test the mechanical properties of their environment provide insight into the role of aberrant mechanosensing in cancer progression. In this review article, we focus on the role of high stiffness on cancer progression, with particular emphasis on tumor growth; we discuss the mechanisms of mechanosensing and mechanotransduction, and their dysregulation in cancerous cells; and we propose that a 'yin and yang' type phenomenon exists in the mechanobiology of cancer, whereby a switch in the type of interaction with the extracellular matrix dictates the outcome of the cancer cells.

Focal adhesion kinase inhibitor BI 853520 inhibits cell proliferation, migration and EMT process through PI3K/AKT/mTOR signaling pathway in ovarian cancer

Focal adhesion kinase (FAK) activation has been reported to be associated with cell progression and metastasis in a wide variety of cancer cells. Target treatment by inhibiting FAK has achieved remarkable effects in several cancers, but the effect in ovarian cancer has not been reported. In this study, we determined the role and the underlying molecular mechanism of BI853520, a novel small chemical FAK inhibitor against ovarian cancer. Results show that phosphorylated FAK tyrosine 397 (p-FAK Y397) is highly expressed in ovarian cancer tumor tissues and cell lines (SKOV3 and OVCAR3). BI853520 treatment greatly suppresses cell proliferation, viability, migration, invasion, decreases anchorage-independent growth and motility in vitro. Besides, treatment with BI853520 increases biologic effects following combination with chemotherapy in ovarian cancer cell lines. In addition, BI853520 suppresses EMT in ovarian cancer cell lines. Mechanically, BI853520 treatment downregulates the activation of PI3K/AKT/mTOR signal pathway. Finally, mice model experiments confirm BI853520 treatment dramatically reduces tumor growth in vivo and suppresses the activation of PI3K/AKT/mTOR signal pathway. Taken together, our findings demonstrate that focal adhesion kinase inhibitor BI853520 inhibits cell proliferation, migration, invasion and EMT process through PI3K/AKT/mTOR signaling pathway in ovarian cancer, and BI853520 can offer a preclinical rationale for targeting repression of FAK in ovarian cancer.

Biophysical interactions between components of the tumor microenvironment promote metastasis

During metastasis, tumor cells need to adapt to their dynamic microenvironment and modify their mechanical properties in response to both chemical and mechanical stimulation. Physical interactions occur between cancer cells and the surrounding matrix including cell movements and cell shape alterations through the process of mechanotransduction. The latter describes the translation of external mechanical cues into intracellular biochemical signaling. Reorganization of both the cytoskeleton and the extracellular matrix (ECM) plays a critical role in these spreading steps. Migrating tumor cells show increased motility in order to cross the tumor microenvironment, migrate through ECM and reach the bloodstream to the metastatic site. There are specific factors affecting these processes, as well as the survival of circulating tumor cells (CTC) in the blood flow until they finally invade the secondary tissue to form metastasis. This review aims to study the mechanisms of metastasis from a biomechanical perspective and investigate cell migration, with a focus on the alterations in the cytoskeleton through this journey and the effect of biologic fluids on metastasis. Understanding of the biophysical mechanisms that promote tumor metastasis may contribute successful therapeutic approaches in the fight against cancer.

Design, synthesis, and biological evaluation of 2,4-diamino pyrimidine derivatives as potent FAK inhibitors with anti-cancer and anti-angiogenesis activities

A series of 2,4-diamino pyrimidine (DAPY) derivatives were designed, synthesized, and evaluated as inhibitors of focal adhesion kinase (FAK) with antitumor and anti-angiogenesis activities. Most compounds effectively suppressed the enzymatic activities of FAK, and the IC₅₀s of 11b and 12f were 2.75 and 1.87 nM, respectively. 11b and 12f exhibited strong antiproliferative effects against seven human cancer cells, with IC₅₀ values against two FAK-overexpressing pancreatic cancer cells (PANC-1 and BxPC-3) of 0.98 μM, 0.55 μM, and 0.11 μM, 0.15 μM, respectively. Moreover, 11b and 12f obviously suppressed the colony formation, migration, and invasion of PANC-1 cells in a dose-dependent manner. Meanwhile, these two compounds could induce the apoptosis of PANC-1 cells and arrest the cell cycle in G2/M phase according to the flow cytometry assay. Western blot revealed that 11b and 12f effectively inhibited the FAK/PI3K/Akt signal pathway and significantly decreased the expression of cyclin D1 and Bcl-2. In addition, compounds 11b and 12f potently inhibited the antiproliferative of HUVECs and obviously altered the cell morphology. 11b and 12f also significantly inhibited the migration, tube formation of HUVECs and severely impaired the angiogenesis in the zebrafish model. Overall, these results revealed the potential of compounds 11b and 12f as promising candidates for further preclinical studies.

Progress in the Development of Small Molecular Inhibitors of Focal Adhesion Kinase (FAK)

Focal adhesion kinase (FAK) is a nonreceptor intracellular tyrosine kinase that plays an essential role in cancer cell adhesion, survival, proliferation, and migration through both its enzymatic activities and scaffolding functions. Overexpression of FAK has been found in many human cancer cells from different origins, which promotes tumor progression and influences clinical outcomes in different classes of human tumors. Therefore, FAK has been considered as a promising target for small molecule anticancer drug development. Many FAK inhibitors targeting different domains of FAK with various mechanisms of functions have been reported, including kinase domain inhibitors, FERM domain inhibitors, and FAT domain inhibitors. In addition, FAK-targeting PROTACs, which can induce the degradation of FAK, have also been developed. In this Perspective, we summarized the progress in the development of small molecular FAK inhibitors and proposed the perspectives for the future development of agents targeting FAK.

Molecular dynamics simulation, free energy landscape and binding free energy computations in exploration the anti-invasive activity of amygdalin against metastasis

BACKGROUND AND OBJECTIVE

Historically, amygdalin has been used as alternative medicine or in vitro and in vivo studies, but no single study exists which discusses the structural mechanism of amygdalin at a molecular level. This paper inquiries into the inhibitory actions of amygdalin on the selected targets: AKT1, FAK, and ILK, which are regulators for various mediated signaling pathways, and are associated with cell adhesion, migration, and differentiation. In order to get details at the molecular level of amygdalin's inhibitory activities against chosen proteins, molecular modeling and simulation techniques including double docking, molecular dynamics simulation, free energy landscape analysis, and binding free energy calculation were exerted.

METHODS

To get molecular level details of amygdalin inhibitory effects against the relevant proteins; here the utilized tools are the following: the double docking, molecular dynamics simulation, free energy landscape analysis, g_mmpbsa, and interaction entropy were used to evaluate the inhibitory activity against targeted proteins.

RESULTS

The computational calculations revealed that amygdalin inhibits the selected targets via block the ATP-binding pocket of AKT1, FAK, and ILK by forming stable hydrogen bonds. Moreover, free energy landscape, FEL exposed that amygdalin stabilized the global conformations of both FAK and ILK proteins to the minimum global energy besides it reduced the essential dynamics of FAK and ILK proteins. MMPBSA computations provided further evidence for amygdalin's stability inside the ATP-binding pocket of AKT1, FAK, and ILK with a binding free energy of 45.067, -13.033, 13.109 kJ/mol, respectively. The binding free energies are lastly consistent with the hydrogen bonding and pairs within 0.35 nm results. The decomposition of binding energy shows the pivotal amino acid residues responsible for the stability of amygdalin's interactions inside the ATP-binding sites by forming hydrogen bonds.

CONCLUSIONS

Before this work, it was enigmatic to make predictions about how amygdalin inhibits metastasis of cancer. But the computational results contribute in several ways to our understanding of amygdalin activity and provide a basic insight into the activity of amygdalin as a multi-target drug in the metastasis and invasion of cancer.

Regulation of Src Family Kinases during Colorectal Cancer Development and Its Clinical Implications

Src family kinases (SFKs) are non-receptor kinases that play a critical role in the pathogenesis of colorectal cancer (CRC). The expression and activity of SFKs are upregulated in patients with CRC. Activation of SFKs promotes CRC cell proliferation, metastases to other organs and chemoresistance, as well as the formation of cancer stem cells (CSCs). The enhanced expression level of Src is associated with decreased survival in patients with CRC. Src-mediated regulation of CRC progression involves various membrane receptors, modulators, and suppressors, which regulate Src activation and its downstream targets through various mechanisms. This review provides an overview of the current understanding of the correlations between Src and CRC progression, with a special focus on cancer cell proliferation, invasion, metastasis and chemoresistance, and formation of CSCs. Additionally, this review discusses preclinical and clinical strategies to improve the therapeutic efficacy of drugs targeting Src for treating patients with CRC.

Involvement of intracellular caveolin-1 distribution in the suppression of antigen-induced mast cell activation by cationic liposomes

Cationic liposomes are commonly used as vectors to effectively introduce foreign genes into target cells. In another function, we recently showed that cationic liposomes bound to the mast cell surface suppress the degranulation induced by the cross-linking of high-affinity immunoglobulin E receptor in a time- and dose-dependent manner. This suppression is mediated by the impairment of the sustained level of intracellular Ca²⁺ concentration ([Ca²⁺ ]_i ) via the inhibition of store-operated Ca²⁺ entry. Further, we revealed that the mechanism underlying an impaired [Ca²⁺ ]_i increase is the inhibition of the activation of the phosphatidylinositol 3-kinase (PI3K)-Akt pathway. Yet, how cationic liposomes inhibit the PI3K-Akt pathway is still unclear. Here, we focused on caveolin-1, a major component of caveolae, which is reported to be involved in the activation of the PI3K-Akt pathway in various cell lines. In this study, we showed that caveolin-1 translocated from the cytoplasm to the plasma membrane after the activation of mast cells and colocalized with the p85 subunit of PI3K, which seemed to be essential for PI3K activity. Meanwhile, cationic liposomes suppressed the translocation of caveolin-1 to the plasma membrane and the colocalization of caveolin-1 with PI3K p85 also at the plasma membrane. This finding provides new information for the development of therapies using cationic liposomes against allergies.

The Extracellular, Cellular, and Nuclear Stiffness, a Trinity in the Cancer Resistome-A Review

Alterations in mechano-physiological properties of a tissue instigate cancer burdens in parallel to common genetic and epigenetic alterations. The chronological and mechanistic interrelation between the various extra- and intracellular aspects remains largely elusive. Mechano-physiologically, integrins and other cell adhesion molecules present the main mediators for transferring and distributing forces between cells and the extracellular matrix (ECM). These cues are channeled via focal adhesion proteins, termed the focal adhesomes, to cytoskeleton and nucleus and vice versa thereby affecting the pathophysiology of multicellular cancer tissues. In combination with simultaneous activation of diverse downstream signaling pathways, the phenotypes of cancer cells are created and driven characterized by deregulated transcriptional and biochemical cues that elicit the hallmarks of cancer. It, however, remains unclear how elastostatic modifications, i.e., stiffness, in the extracellular, intracellular, and nuclear compartment contribute and control the resistance of cancer cells to therapy. In this review, we discuss how stiffness of unique tumor components dictates therapy response and what is known about the underlying molecular mechanisms.

Biophysics of Cell-Substrate Interactions Under Shear

Cells adhere to substrates through mechanosensitive focal adhesion complexes. Measurements that probe how cells detach from substrates when they experience an applied force connect molecular-scale aspects of cell adhesion with the biophysical properties of adherent cells. Such forces can be applied through shear devices that flow fluid in a controlled manner across cells. The signaling pathways associated with focal adhesions, in particular those that involve integrins and receptor tyrosine kinases, are complex, receiving mechano-chemical feedback from the sensing of substrate stiffness as well as of external forces. This article reviews the signaling processes involved in mechanosensing and mechanotransduction during cell-substrate interactions, describing the role such signaling plays in cancer metastasis. We examine some recent progress in quantifying the strength of these interactions, describing a novel fluid shear device that allows for the visualization of the cell and its sub-cellular structures under a shear flow. We also summarize related results from a biophysical model for cellular de-adhesion induced by applied forces. Quantifying cell-substrate adhesions under shear should aid in the development of mechano-diagnostic techniques for diseases in which cell-adhesion is mis-regulated, such as cancers.

TAE226, a dual inhibitor of focal adhesion kinase and insulin-like growth factor-I receptor, is effective for Ewing sarcoma

The outcomes for relapsed and metastatic Ewing sarcoma (EWS) is extremely poor. Therefore, it is important to identify the tumor‐specific targets in these intractable diseases. High focal adhesion kinase (FAK) transcript expression levels in EWS cell lines are known. TAE226 is a dual inhibitor of FAK and insulin‐like growth factor‐I receptor (IGF‐IR), while PF‐562,271 is a dual inhibitor of FAK and proline‐rich tyrosine kinase 2. We compared the cytotoxicity of TAE226 and PF‐562,271 toward three EWS cell lines. TAE226 strongly inhibited proliferation of three cell lines when compared with PF‐562,271. Furthermore, we investigated the efficacy of TAE226 as well as its mechanism of action against EWS. A stable EWS cell line with FAK and IGF‐IR knocked down was established, and microarray analysis revealed dysregulated expression in various pathways. TAE226 treatment of EWS cell lines induced cell cycle arrest, apoptosis, AKT dephosphorylation, and inhibition of invasion. We demonstrated that TAE226 drastically inhibits the local growth of primary tumors and metastasis in EWS using mouse models. Furthermore, the combination of TAE226 and conventional chemotherapy proved to exert synergistic effects. TAE226 may be a candidate single agent or combined therapy drug to be developed for patients who have relapse and metastatic EWS tumors in future.

Identification and integrative analysis of microRNAs and mRNAs involved in proliferation and invasion of pressure‑treated human liver cancer cell lines

Mechanical pressure may contribute to the development of cancer; however, there is currently no evidence regarding the effect of mechanical pressure on liver cancer. In the present study, 2- and 3-dimensional pressure-loading systems were used to exert pressure on HepG2 and Huh-7 cell lines. Cell proliferation and flow cytometry analyses were undertaken to observe the proliferative ability of pressure-loaded cells. In addition, Transwell, wound-healing and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) assays were applied to evaluate the migratory and invasive ability of pressurized cells. Analyses of microRNA (miRNA) and mRNA expression profiles were performed to screen for differentially expressed miRNAs and mRNAs, which were validated by RT-qPCR. Bioinformatics analyses were subsequently performed to investigate the putative target genes and associated pathways. The proliferation and invasion of HepG2 and Huh-7 cell lines were significantly increased under a pressure of 15 mmHg for 24 h. Under this condition, five differentially expressed miRNAs (fold change ≥1.2, P≤0.05) and 10,150 differentially expressed mRNAs (fold change ≥2, P≤0.05) were identified. A total of 1,309 genes were identified from the integrative analysis of miRNAs and mRNAs. In addition, the bioinformatics analyses revealed that the majority of these miRNAs and mRNAs were associated with several pathways associated with cell proliferation and invasion, including ‘PI3K/Akt signaling pathway’, ‘focal adhesion’, ‘integrin-mediated signaling pathway’, ‘FOXO signaling pathway’ and ‘Hippo signaling pathway’. The present study described the pressure-dependent proliferation and invasion of liver cancer cells, and revealed the potential molecular mechanisms underlying them. The identification of miRNAs and their putative targets may also result in novel treatment strategies for liver cancer.

ZINC4085554 inhibits cancer cell adhesion by interfering with the interaction of Akt1 and FAK

Perioperative or circulatory forces enhance disseminated cancer cell adhesiveness by modulating focal adhesion kinase (FAK)-Akt1 interaction. Selectively blocking FAK-Akt1 interaction by a peptide derived from the FAK-Four-point-one, ezrin, radixin, moesin (FERM) domain reduces colon cancer cell adhesion in vitro and in mice. A preliminary in silico screening identified two small molecules resembling a peptide that may inhibit pressure-stimulated SW620 cancer cell adhesion to collagen I. The present study selected ZINC4085554 for further study to validate its proposed mechanism of action, using human SW620 colon cancer cells as a model system. At 25 and 50 µM, ZINC4085554 inhibited the pressure-stimulated adhesion of SW620 colon cancer cells to collagen I. This molecule prevented pressure-stimulated FAK-Tyr-397 phosphorylation; however, it did not affect Akt1-Ser-473 phosphorylation, indicating that ZINC4085554 acts downstream of Akt1, while Akt-Thr-308 remains unchanged in the presence of pressure and or ZINC4085554. Indeed, ZINC4085554 inhibited FAK-Akt1 interaction in response to increased extracellular pressure, consistent with the proposed mechanism. ZINC4085554 did not inhibit FAK-Tyr-397 phosphorylation in response to cell adhesion to collagen I, indicating the specificity of the inhibitory effects towards force-stimulated pathways. Finally, the present study confirmed that ZINC4085554 at 50 µM prevented pressure-activation of adhesion to surgical wounds in vivo in parallel to its ablation of intracellular signaling. In summary, ZINC4085554 is a small molecule mimicking part of the structure of FAK that reduces cancer cell adhesion by impairing pressure-stimulated FAK-Akt1 interaction and its downstream consequences. ZINC4085554 does not inhibit conventional outside-in FAK signaling and may be less toxic than global FAK inhibitors, and ZINC4085554 may be an important step towards the inhibition of metastasis.

Focal adhesion kinase (FAK) activation by estrogens involves GPER in triple-negative breast cancer cells

BACKGROUND

Focal adhesion kinase (FAK) is a cytoplasmatic protein tyrosine kinase that associates with both integrins and growth factor receptors toward the adhesion, migration and invasion of cancer cells. The G-protein coupled estrogen receptor (GPER) has been involved in the stimulatory action of estrogens in breast tumor. In this study, we have investigated the engagement of FAK by GPER signaling in triple negative breast cancer (TNBC) cells.

METHODS

Publicly available large-scale database and patient data sets derived from "The Cancer Genome Atlas" (TCGA; www.cbioportal.org ) were used to assess FAK expression in TNBC, non-TNBC tumors and normal breast tissues. MDA-MB 231 and SUM159 TNBC cells were used as model system. The levels of phosphorylated FAK, other transduction mediators and target genes were detected by western blotting analysis. Focal adhesion assay was carried out in order to determine the focal adhesion points and the formation of focal adhesions (FAs). Luciferase assays were performed to evaluate the promoters activity of c-FOS, EGR1 and CTGF upon GPER activation. The mRNA expression of the aforementioned genes was measured by real time-PCR. Boyden chamber and wound healing assays were used in order to evaluate cell migration. The statistical analysis was performed by ANOVA.

RESULTS

We first determined by bioinformatic analysis that the mRNA expression levels of the gene encoding FAK, namely PTK2, is higher in TNBC respect to non-TNBC and normal breast tissues. Next, we found that estrogenic GPER signaling triggers Y397 FAK phosphorylation as well as the increase of focal adhesion points (FAs) in TNBC cells. Besides, we ascertained that GPER and FAK activation are involved in the STAT3 nuclear accumulation and gene expression changes. As biological counterpart, we show that FAK inhibition prevents the migration of TNBC cells upon GPER activation.

CONCLUSIONS

The present data provide novel insights regarding the action of FAK in TNBC. Moreover, on the basis of our findings estrogenic GPER signaling may be considered among the transduction mechanisms engaging FAK toward breast cancer progression.

Increased extracellular matrix density disrupts E-cadherin/β-catenin complex in gastric cancer cells

During gastric cancer (GC) progression, increased extracellular matrix (ECM) deposition, notably collagen type I, correlates with an overall increase in expression of the mesenchymal phenotype. In GC tissue, the intestinal epithelium exhibits impaired cell-cell adhesion and enhanced cell-ECM adhesion. The alteration of intercellular integrity is one of tumorigenesis feature including tumor invasion and metastasis. Using a density-varying ECM, we studied the effect of ECM density on both intercellular- and ECM-interactions according to alterations of ECM-mediated signaling. A dense collagen matrix increases integrin-mediated cell-ECM interactions with phosphorylated FAK and ERK signaling in human gastric adenocarcinoma cells (AGS, MKN74), which regulates GC proliferation and the chemotherapeutic response. In addition, GC cells exhibited a disrupted membranous E-cadherin/β-catenin complex and, remarkably, showed cytoplasmic or nucleic localization of β-catenin in response to collagen density. Furthermore, we found that membranous E-cadherin/β-catenin complex could be recovered by inhibiting the phosphorylation of FAK, which in turn influences the chemotherapeutic effect. These results provide insight into how matrix density differentially regulates cancer cell phenotype and may have significant implications for the design of biomaterials with appropriate physical properties for in vitro tumor models.

Long non-coding RNA CUDR promotes malignant phenotypes in pancreatic ductal adenocarcinoma via activating AKT and ERK signaling pathways

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies, with a marked potential for invasion and metastasis. Emerging evidence has suggested that dysregulation of long non-coding RNAs (lncRNAs) is associated with the development of multiple types of cancer. However, the function of lncRNAs in PDAC is poorly known. In the present study, a microarray assay was used to screen for differently expressed lncRNAs in PDAC and it was identified that cancer upregulated drug resistance (CUDR) was upregulated in PDAC. CUDR increased PDAC cell proliferation, migration and invasion, inhibited apoptosis, and promoted drug resistance; it also regulated the PDAC cell epithelial-mesenchymal transition. The CUDR-induced PDAC malignant phenotypes is via the protein kinase B and extracellular-signal-regulated kinase signaling pathways. Downregulation of CUDR may be a novel therapeutic strategy to prevent PDAC development and drug resistance in the future.

Alternagin-C binding to α2β1 integrin controls matrix metalloprotease-9 and matrix metalloprotease-2 in breast tumor cells and endothelial cells

Background

Matrix metalloproteinases (MMPs) are key players in tumor progression, helping tumor cells to modify their microenvironment, which allows cell migration to secondary sites. The role of integrins, adhesion receptors that connect cells to the extracellular matrix, in MMP expression and activity has been previously suggested. However, the mechanisms by which integrins control MMP expression are not completely understood. Particularly, the role of α2β1 integrin, one of the major collagen I receptors, in MMP activity and expression has not been studied. Alternagin-C (ALT-C), a glutamate-cysteine-aspartate-disintegrin from Bothrops alternatus venom, has high affinity for an α2β1 integrin. Herein, we used ALT-C as a α2β1 integrin ligand to study the effect of ALT-C on MMP-9 and MMP-2 expression as well as on tumor cells, fibroblats and endothelial cell migration.

Methods

ALT-C was purified by two steps of gel filtration followed by anion exchange chromatography. The α₂β₁ integrin binding properties of ALT-C, its dissociation constant (K_d) relative to this integrin and to collagen I (Col I) were determined by surface plasmon resonance. The effects of ALT-C (10, 40, 100 and 1000 nM) in migration assays were studied using three human cell lines: human fibroblasts, breast tumor cell line MDA-MB-231, and microvascular endothelial cells HMEC-1, considering cells found in the tumor microenvironment. ALT-C effects on MMP-9 and MMP-2 expression and activity were analyzed by quantitative PCR and gelatin zymography, respectively. Focal adhesion kinase activation was determined by western blotting.

Results

Our data demonstrate that ALT-C, after binding to α₂β₁ integrin, acts by two distinct mechanisms against tumor progression, depending on the cell type: in tumor cells, ALT-C decreases MMP-9 and MMP-2 contents and activity, but increases focal adhesion kinase phosphorylation and transmigration; and in endothelial cells, ALT-C inhibits MMP-2, which is necessary for tumor angiogenesis. ALT-C also upregulates c-Myc mRNA level, which is related to tumor suppression.

Conclusion

These results demonstrate that α₂β₁ integrin controls MMP expression and reveal this integrin as a target for the development of antiangiogenic and antimetastatic therapies.

Electronic supplementary material

The online version of this article (10.1186/s40409-018-0150-2) contains supplementary material, which is available to authorized users.

Inhibition of cell migration by focal adhesion kinase: Time-dependent difference in integrin-induced signaling between endothelial and hepatoblastoma cells

Angiogenesis plays an important role in the development and progression of tumors, and it involves a series of signaling pathways contributing to the migration of endothelial cells for vascularization and to the invasion of cancer cells for secondary tumor formation. Among these pathways, the focal adhesion kinase (FAK) signaling cascade has been implicated in a variety of human cancers in connection with cell adhesion and migration events leading to tumor angiogenesis, metastasis and invasion. Therefore, the inhibition of FAK in endothelial and/or cancer cells is a potential target for anti-angiogenic therapy. In the present study, a small-molecule FAK inhibitor, 1,2,4,5-benzenetetramine tetrahydrochloride (Y15), was used to study the effects of FAK inhibition on the adhesion and migration behaviors of vascular endothelial cells (VECs) and human hepatoblastoma cells. Furthermore, the time-dependent differences in proteins associated with the integrin-mediated FAK/Rho GTPases signaling pathway within 2 h were examined. The results indicated that the inhibition of FAK significantly decreased the migration ability of VECs and human hepatoblastoma cells in a dose-dependent manner. Inhibition of FAK promoted cell detachment by decreasing the expression of focal adhesion components, and blocked cell motility by reducing the level of Rho GTPases. However, the expression of crucial proteins involved in integrin-induced signaling in two cell lines exhibited a time-dependent difference with increased duration of FAK inhibitor treatment, suggesting different mechanisms of FAK-mediated cell migration behavior. These results suggest that the mechanism underlying FAK-mediated adhesion and migration behavior differs among various cells, which is expected to provide evidence for future FAK therapy targeted against tumor angiogenesis.

Microenvironment Influences Cancer Cell Mechanics from Tumor Growth to Metastasis

The microenvironment in a solid tumor includes a multitude of cell types, matrix proteins, and growth factors that profoundly influence cancer cell mechanics by providing both physical and chemical stimulation. This tumor microenvironment, which is both dynamic and heterogeneous in nature, plays a critical role in cancer progression from the growth of the primary tumor to the development of metastatic and drug-resistant tumors. This chapter provides an overview of the biophysical tools used to study cancer cell mechanics and mechanical changes in the tumor microenvironment at different stages of cancer progression, including growth of the primary tumor, local invasion, and metastasis. Quantitative single cell biophysical analysis of intracellular mechanics, cell traction forces, and cell motility can easily be combined with analysis of critical cell fate processes, including adhesion, proliferation, and drug resistance, to determine how changes in mechanics contribute to cancer progression. This biophysical approach can be used to systematically investigate the parameters in the tumor that control cancer cell interactions with the stroma and to identify specific conditions that induce tumor-promoting behavior, along with strategies for inhibiting these conditions to treat cancer. Increased understanding of the underlying biophysical mechanisms that drive cancer progression may provide insight into novel therapeutic approaches in the fight against cancer.

Sustained activation of the AKT/mTOR and MAP kinase pathways mediate resistance to the Src inhibitor, dasatinib, in thyroid cancer

New targeted therapies are needed for advanced thyroid cancer. Our lab has shown that Src is a key mediator of tumorigenic processes in thyroid cancer. However, single-agent Src inhibitors have had limited efficacy in solid tumors. In order to more effectively target Src in the clinic, our lab has previously generated four thyroid cancer cell lines that are resistant to dasatinib through gradual dose escalation. We further tested two additional Src inhibitors and shown the dasatinib-resistant (DasRes) cells exhibit cross-resistance to saracatinib, but are sensitive to bosutinib, suggesting that unique off-targets of bosutinib play an important role in mediating sensitivity to bosutinib. To identify the kinases targeted by dasatinib and bosutinib, we utilized an unbiased compound centric chemical proteomics screen. We identified 33 kinases that were enriched in the bosutinib pull down. Using the STRING database to map protein-protein interactions of the unique bosutinib targets, we identified a signaling axis which included mTOR, FAK, and MEK. Inhibition of the mTOR, MEK, and Src/FAK nodes simultaneously was the most effective at reducing cell growth and survival. Overall, these studies have identified key mediators of Src inhibitor resistance, and show that targeting these signaling nodes are necessary for anti-tumor efficacy.

Insufficient Radiofrequency Ablation Treated Hepatocellular Carcinoma Cells Promote Metastasis by Up-Regulation ITGB3

Radiofrequency ablation (RFA) is one of the standards of care for early stage hepatocellular carcinoma (HCC). However, rapid progression of residual tumor after RFA has been confirmed. The aim of this study was to investigate the underlying mechanism of this phenomenon. Human HCC cell lines HCCLM3 and HepG2 were employed to establish insufficient RFA models in vivo and in vitro, respectively. The effects of insufficient RFA on metastatic potential of residual tumors were evaluated. The molecular changes after insufficient RFA were evaluated by PCR array, western blot, immunofluorescence, and immunohistochemistry. Results showed that insufficient RFA significantly promoted lung and intrahepatic residual tumor cells in vivo, and heat intervention promoted migration and invasion of hepatoma cells in vitro. PCR array revealed that the expression of integrin β3 (ITGB3) and MMP2 were up-regulated in the residual tumors of HCCLM3 xenograft model. The up-regulation of ITGB3 was confirmed by qRT-PCR, Western blot and immunohistochemistry. Knockdown ITGB3 expression in HCCLM3 cells by shRNA significantly lowered the pro-metastatic effects of insufficient RFA. Mechanism studies indicated that ITGB3 mediated the expression of MMP2 by activing FAK/PI3K/AKT signaling pathway. The up-regulation of ITGB3 contributed to enhanced metastatic potential of residual cancer in HCCLM3 model after insufficient RFA. Targeting ITGB3 expression may further improve the clinical effects of RFA.

Activation of Focal Adhesion Kinase and Src Mediates Acquired Sorafenib Resistance in A549 Human Lung Adenocarcinoma Xenografts

Despite encouraging clinical results with sorafenib monotherapy in patients with KRAS-mutant non-small-cell lung cancer (NSCLC), the overall survival benefit of this drug is limited by the inevitable development of acquired resistance. The exact mechanism underlying acquired sorafenib resistance in KRAS-mutant NSCLC is unclear. In this study, the mechanism of acquired sorafenib resistance was explored using a biologically relevant xenograft model, which was established by using the A549 human lung adenocarcinoma cell line and an in vivo-derived, sorafenib-resistant A549 subline (A549/SRFres). Results from the initial study demonstrated that sorafenib treatment significantly decreased E-cadherin (P < 0.05) levels but significantly increased matrix metallopeptidase 9 (MMP9) levels (P < 0.01) in A549/SRFres tumors, whereas expression levels of phospho-protein kinase B (AKT), phospho-focal adhesion kinase (FAK), and phospho-Src were elevated in sorafenib-treated A549 and A549/SRFres tumors. We next examined whether concomitant dasatinib treatment could overcome acquired sorafenib resistance by blocking the FAK/Src escape route that mediates resistance. Despite the observed in vitro synergy between sorafenib and dasatinib, the in vivo antitumor effect of half-dose sorafenib-dasatinib combination therapy was inferior to that of the full-dose sorafenib treatment. Although the sorafenib-dasatinib combination effectively inhibited Src and AKT phosphorylation, it did not block the Y576/577-FAK phosphorylation, nor did it decrease vimentin protein expression; unexpectedly, it increased Y397-FAK phosphorylation and MMP9 protein expression in tumors. These results suggest that acquired sorafenib resistance in KRAS-mutant A549 xenografts involves the compensatory activation of FAK and Src, and Src inhibition alone is insufficient to diminish sorafenib-promoted epithelial-mesenchymal transition process and invasive potentials in tumors.

Effect of integrin‑linked kinase gene silencing on microRNA expression in ovarian cancer

Integrin‑linked kinase (ILK) is overexpressed in ovarian cancer (OC), and ILK gene silencing results in apoptosis in OC cells. In the present study, the mechanism by which ILK induces apoptosis was explored from the perspective of microRNA (miRNA) expression. Alterations in the global miRNA expression profile were detected using a miRNA microarray after OC cells were transduced with an ILK small hairpin RNA lentivirus. ILK silencing led to a significant upregulation of 14 miRNAs by at least 1.5‑fold. These findings were validated by reverse transcription‑quantitative polymerase chain reaction. A pathway analysis of experimentally validated target genes revealed the inhibition of multiple cancer‑associated signaling pathways and the wnt signaling pathway. Compared with cells transfected with scrambled RNA, the ILK‑silenced cells had remarkably lower expression of wnt ligands (wnt3a, wnt4 and wnt5a) and downstream β‑catenin. ILK silencing led to apoptosis of OC cells and impaired the migratory ability. Taken together, the present results suggested that miRNA‑mediated wnt pathway alterations are involved in the anti‑apoptotic role of ILK in OC. It was also indicated that ILK silencing reduced the ability of OC cells to adhere to fibronectin, which may lead to unstable focal contact. Consistently, the phosphorylation levels of focal adhesion kinase and RAC‑α serine/threonine protein kinase were downregulated. The present work demonstrated the first global miRNA expression profile of OC cells when ILK was inhibited, and this expression profile may provide a basis for the development of biomarkers and therapeutic targets for OC.

Inhibition of pressure-activated cancer cell adhesion by FAK-derived peptides

Forces within the surgical milieu or circulation activate cancer cell adhesion and potentiate metastasis through signaling requiring FAK-Akt1 interaction. Impeding FAK-Akt1 interaction might inhibit perioperative tumor dissemination, facilitating curative cancer surgery without global FAK or AKT inhibitor toxicity. Serial truncation and structurally designed mutants of FAK identified a seven amino acid, short helical structure within FAK that effectively competes with Akt1-FAK interaction. Adenoviral overexpression of this FAK-derived peptide inhibited pressure-induced FAK phosphorylation and AKT-FAK coimmunoprecipitation in human SW620 colon cancer cells briefly exposed to 15mmHg increased pressure, consistent with laparoscopic or post-surgical pressures. Adenoviral FAK-derived peptide expression prevented pressure-activation of SW620 adhesion not only to collagen-I-coated plates but also to murine surgical wounds. A scrambled peptide did not. Finally, we modeled operative shedding of tumor cells before irrigation and closure by transient cancer cell adhesion to murine surgical wounds before irrigation and closure. Thirty minute preincubation of SW620 cells at 15mmHg increased pressure impaired subsequent tumor free survival in mice exposed to cells expressing the scrambled peptide. The FAK-derived sequence prevented this. These results suggest that blocking FAK-Akt1 interaction may prevent perioperative tumor dissemination and that analogs or mimics of this 7 amino acid FAK-derived peptide could impair metastasis.

The cancer cell adhesion resistome: mechanisms, targeting and translational approaches

Cell adhesion-mediated resistance limits the success of cancer therapies and is a great obstacle to overcome in the clinic. Since the 1990s, where it became clear that adhesion of tumor cells to the extracellular matrix is an important mediator of therapy resistance, a lot of work has been conducted to understand the fundamental underlying mechanisms and two paradigms were deduced: cell adhesion-mediated radioresistance (CAM-RR) and cell adhesion-mediated drug resistance (CAM-DR). Preclinical work has evidently demonstrated that targeting of integrins, adapter proteins and associated kinases comprising the cell adhesion resistome is a promising strategy to sensitize cancer cells to both radiotherapy and chemotherapy. Moreover, the cell adhesion resistome fundamentally contributes to adaptation mechanisms induced by radiochemotherapy as well as molecular drugs to secure a balanced homeostasis of cancer cells for survival and growth. Intriguingly, this phenomenon provides a basis for synthetic lethal targeted therapies simultaneously administered to standard radiochemotherapy. In this review, we summarize current knowledge about the cell adhesion resistome and highlight targeting strategies to override CAM-RR and CAM-DR.

Allicin inhibits the invasion of lung adenocarcinoma cells by altering tissue inhibitor of metalloproteinase/matrix metalloproteinase balance via reducing the activity of phosphoinositide 3-kinase/AKT signaling

Allicin, the main active principle associated with Allium sativum chemistry, has various antitumor activities. However, to the best of our knowledge, there is no available information to address the anti-invasive effect and associated mechanism in lung adenocarcinoma. In the present study, cell viability assay, cell adhesion assay, western blot analysis, Transwell migration and invasion assays and reverse transcription-quantitative polymerase chain reaction were performed. Allicin was identified to inhibit the adhesion, invasion and migration of lung adenocarcinoma cells in a dose-dependent manner, accompanied by decreasing mRNA and protein levels of matrix metalloproteinase (MMP)-2 and MMP-9. Conversely, the mRNA and protein levels of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 were increased in a dose-dependent manner. Furthermore, it was revealed that allicin treatment significantly suppressed the phosphorylation of AKT (P<0.05), but not the total protein expression of AKT. Combined treatment with LY294002, an inhibitor of phosphoinositide 3-kinase (PI3K)/AKT signaling, and allicin led to the synergistic reduction of MMP-2 and MMP-9 expression, followed by an increase in TIMP-1 and TIMP-2 expression. The invasive capabilities of lung adenocarcinoma cells were also suppressed. However, insulin-like growth factor-1 (an activator of PI3K/AKT signaling) reversed the effects of allicin on cell invasion and expression of MMP-2, MMP-9, TIMP-1 and TIMP-2. The present study concluded that allicin may inhibit invasion of lung adenocarcinoma cells by altering TIMP/MMP balance, via reducing the activity of the PI3K/AKT signaling pathway. This indicated that allicin may be recognized as an anti-invasive agent for lung adenocarcinoma treatment.

Focal adhesion kinases crucially regulate TGFβ-induced migration and invasion of bladder cancer cells via Src kinase and E-cadherin

Focal adhesion kinase (FAK) is a non-receptor protein-tyrosine kinase that is triggered off by special extracellular signals such as some growth factors and integrins. FAK is found in cell-matrix attachment sites and implicated in cell migration, invasion, movement, gene expression, survival and apoptosis. In this study, we aimed to investigate whether FAK plays a role in invasion and migration of bladder cancer cells. Using an FAK-specific small interfering RNA (siRNA) and an FAK inhibitor PF-228, we found that inhibition of FAK tyrosine phosphorylation or knockdown of FAK suppressed invasion and migration of bladder cancer cells. Src is an important mediator of FAK-regulated migratory and invasive activity. Tyrosine phosphorylation of Src and FAK is mutually dependent and plays a key role in transforming growth factor beta (TGFβ)-induced invasion and migration. E-cadherin acts downstream of FAK and is a critical negative regulator in FAK-regulated invasion and migration of bladder cancer cells. These findings imply that FAK is involved in oncogenic signaling of invasion and migration, which can be a novel therapeutic target to treat patients with bladder cancer.

Arachidonic acid triggers [Ca2+]i increases in rat round spermatids by a likely GPR activation, ERK signalling and ER/acidic compartments Ca2+ release

Arachidonic acid (AA), a compound secreted by Sertoli cells (SC) in a FSH-dependent manner, is able to induce the release of Ca²⁺ from internal stores in round spermatids and pachytene spermatocytes. In this study, the possible site(s) of action of AA in round spermatids, the signalling pathways associated and the intracellular Ca²⁺ stores targeted by AA-induced signalling were pharmacologically characterized by measuring intracellular Ca²⁺ using fluorescent Ca²⁺ probes. Our results suggest that AA acts by interacting with a fatty acid G protein coupled receptor, initiating a G protein signalling cascade that may involve PLA2 and ERK activation, which in turn opens intracellular ryanodine-sensitive channels as well as NAADP-sensitive channels in acidic intracellular Ca²⁺ stores. The results presented here also suggest that AMPK and PKA modulate this AA-induced Ca²⁺ release from intracellular Ca²⁺ stores in round spermatids. We propose that unsaturated free fatty acid lipid signalling in the seminiferous tubule is a novel regulatory component of rat spermatogenesis.

Cordycepin inhibits chondrocyte hypertrophy of mesenchymal stem cells through PI3K/Bapx1 and Notch signaling pathway

Mesenchymal stem cells (MSCs) are widely used in cartilage tissue engineering to repair articular cartilage defects. However, hypertrophy of chondrocytes derived from MSCs might hinder the stabilization of hyaline cartilage. Thus, it is very important to find a suitable way to maintain the chondrogenic phenotype of chondrocytes. It has been reported that cordycepin has anti-inflammatory and anti-tumor functions. However, the role of cordycepin in chondrocyte hypertrophy remains unclear. Therefore, the objective of this study was to determine the effect of cordycepin on chondrogenesis and chondrocyte hypertrophy in MSCs and ATDC5 cells. Cordycepin upregulated chondrogenic markers including Sox9 and collagen type II while down-regulated hypertrophic markers including Runx2 and collagen type X. Further exploration showed that cordycepin promoted chondrogenesis through inhibiting Nrf2 while activating BMP signaling. Besides, cordycepin suppressed chondrocyte hypertrophy through PI3K/Bapx1 pathway and Notch signaling. Our results indicated cordycepin had the potential to maintain chondrocyte phenotype and reconstruct engineered cartilage. [BMB Reports 2016; 49(10): 548-553]

Thyroid Hormone Controls Breast Cancer Cell Movement via Integrin αV/β3/SRC/FAK/PI3-Kinases

Thyroid hormones (TH) play a fundamental role in diverse processes, including cellular movement. Cell migration requires the integration of events that induce changes in cell structure towards the direction of migration. These actions are driven by actin remodeling and stabilized by the development of adhesion sites to extracellular matrix via transmembrane receptors linked to the actin cytoskeleton. Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that promotes cell migration and invasion through the control of focal adhesion turnover. In this work, we demonstrate that the thyroid hormone triiodothyronine (T3) regulates actin remodeling and cell movement in breast cancer T-47D cells through the recruitment of FAK. T3 controls FAK phosphorylation and translocation at sites where focal adhesion complexes are assembled. This process is triggered via rapid signaling to integrin αV/β3, Src, phosphatidylinositol 3-OH kinase (PI3K), and FAK. In addition, we established a cellular model with different concentration of T3 levels: normal, absence, and excess in T-47D breast cancer cells. We found that the expression of Src, FAK, and PI3K remained at normal levels in the excess of T3 model, while it was significantly reduced in the absence model. In conclusion, these results suggest a novel role for T3 as an important modulator of cell migration, providing a starting point for the development of new therapeutic strategies for breast cancer treatment.

LH and FSH promote migration and invasion properties of a breast cancer cell line through regulatory actions on the actin cytoskeleton

Reproductive hormones influence breast cancer development and progression. While the actions of sex steroids in this setting are established, tentative evidence suggests that follicle-stimulating hormone (FSH) and luteinizing hormone (LH) may also play a role, yet this remains elusive. We here identify that T-47D breast cancer cells express functional receptors for FSH and LH, and that these hormones regulate breast cancer cell motility and invasion through the control of the actin cytoskeleton and the formation of cortical actin aggregates and focal adhesion complexes. Such actions are mediated by the cytoskeletal controllers Moesin and focal adhesion kinase (FAK). Moesin is recruited rapidly by FSH and LH through a signaling cascade requiring the G protein Gα₁₃ and the Rho-associated kinase, ROCK-2. FSH and LH activate FAK via a Gα_i/β and c-Src-dependent signaling cascade. Both cascades involve signaling to phosphatidylinositol-3 kinase and Akt. FSH and LH receptors and the related signaling intermediates are necessary for the actions of gonadotrophins on breast cancer cell cytoskeletal rearrangement, migration and invasion. These findings provide original information on the actions of gonadotrophins on breast cancer cells and may have clinical implications for the use of drugs that modulate gonadotrophins in breast cancer patients.

Novel Small Molecule JP-153 Targets the Src-FAK-Paxillin Signaling Complex to Inhibit VEGF-Induced Retinal Angiogenesis

Targeting vascular endothelial growth factor (VEGF) is a common treatment strategy for neovascular eye disease, a major cause of vision loss in diabetic retinopathy and age-related macular degeneration. However, the decline in clinical efficacy over time in many patients suggests that monotherapy of anti-VEGF protein therapeutics may benefit from adjunctive treatments. Our previous work has shown that through decreased activation of the cytoskeletal protein paxillin, growth factor-induced ischemic retinopathy in the murine oxygen-induced retinopathy model could be inhibited. In this study, we demonstrated that VEGF-dependent activation of the Src/FAK/paxillin signalsome is required for human retinal endothelial cell migration and proliferation. Specifically, the disruption of focal adhesion kinase (FAK) and paxillin interactions using the small molecule JP-153 inhibited Src-dependent phosphorylation of paxillin (Y118) and downstream activation of Akt (S473), resulting in reduced migration and proliferation of retinal endothelial cells stimulated with VEGF. However, this effect did not prevent the initial activation of either Src or FAK. Furthermore, topical application of a JP-153-loaded microemulsion affected the hallmark features of pathologic retinal angiogenesis, reducing neovascular tuft formation and increased avascular area, in a dose-dependent manner. In conclusion, our results suggest that using small molecules to modulate the focal adhesion protein paxillin is an effective strategy for treating pathologic retinal neovascularization. To our knowledge, this is the first paradigm validating modulation of paxillin to inhibit angiogenesis. As such, we have identified and developed a novel class of small molecules aimed at targeting focal adhesion protein interactions that are essential for pathologic neovascularization in the eye.

Antitumor activity of 7RH, a discoidin domain receptor 1 inhibitor, alone or in combination with dasatinib exhibits antitumor effects in nasopharyngeal carcinoma cells

Dysregulation of the discoidin domain receptors (DDRs) has been implicated in the development of numerous types of tumors, including head and neck cancer, and nasopharyngeal, breast, ovarian and esophageal carcinomas. Furthermore, agents that inhibit DDR1 activity are hypothesized to be useful for the treatment of nasopharyngeal carcinoma (NPC). The aim of the present study was to evaluate the effect of the DDR1 inhibitory (3-(2-(pyrazolo(1,5-a)pyrimidin-6-yl)-ethynyl)benzamide compound, 7RH, in NPC cells both in vitro and in vivo, and its effect when used in combination with dasatinib, a SRC family kinase (SFK) inhibitor. The effects of 7RH alone or in combination with dasatinib on cell viability were assessed using MTT assays and apoptosis was detected by flow cytometry. In addition, western blotting was performed to analyze the relative protein expression levels of cell cycle-associated genes in human NPC cell lines (CNE1, CNE2, HONE1 and SUNE1). Cell migration was also assessed using cell adhesion assays. Furthermore, tumor xenografts of CNE2 NPC cells were established in nude mice and the growth inhibitory effects of 7RH treatment alone or in combination with dasatinib were evaluated. Finally, knockdown of DDR1 protein expression was achieved by transfection of CNE2 cells with DDR1-specific small interfering RNA. Treatment with 7RH effectively suppressed the proliferation and induced the apoptosis of NPC cells. In addition, the Janus kinase 1 (JAK1)/signal transducer and activator of transcription (STAT3) signaling pathway was downregulated by 7RH, whereas the activities of the Ras/Raf/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) and phosphoinositide 3-kinase (PI3K)/AKT signaling pathways were upregulated in response to 7RH treatment. Furthermore, the expression levels of phosphorylated SRC were increased in NPC cells treated with 7RH; thus indicating that SRC exhibits a vital function in the resistance of NPC cells to 7RH via activation of the PI3K/AKT signaling pathway. The results of the present study indicate that DDR1 and SFK inhibition may present a potential therapeutic strategy for patients with NPC.

Focal Adhesion Kinase Directly Interacts with TSC2 Through Its FAT Domain and Regulates Cell Proliferation in Cashmere Goat Fetal Fibroblasts

Focal adhesion kinase (FAK) is a cytoplasmic nonreceptor tyrosine kinase that senses a variety of extracellular signals, such as growth factors and integrins, to control the process of cell proliferation and metabolism. We cloned three goat FAK transcript variants (KM655805, KM658268, and KM658269) that encode 1052, 1006, and 962 amino-acid residue proteins. Bioinformatics analysis indicated that the putative FAK protein contains an FERM domain, a PTK domain, two Proline-rich regions, and a focal adhesion-targeting (FAT) domain. All the three transcript variants of FAK were detected in seven different goat tissues, and variant 1 had the most accumulation whereas variant 2 and variant 3 had lower accumulation. Treatment of goat fetal fibroblasts (GFbs) with a specific FAK inhibitor, TAE226, inhibited cell proliferation (p < 0.05) and induced damage to the cell morphology in a dose- and time-dependent manner. Further research demonstrated that FAK directly interacted with TSC2 (Tuberous sclerosis 2) tuberin domain through its C-terminus, which contains the complete FAT domain. In conclusion, our results indicated that FAK may be widely expressed in Cashmere goat tissues and its products participate in the mammalian target of rapamycin signaling pathway and cell proliferation through a direct interaction with TSC2 in GFBs.

Activation of focal adhesion kinase through an interaction with β4 integrin contributes to tumorigenicity of colon cancer

High expression of either β4 integrin or focal adhesion kinase (FAK) has been reported in human colon cancer. However, it remains unclear how β4 integrin together with FAK contributes to the tumorigenicity of colon cancer. Here, we demonstrate that the co-overexpression of β4 integrin and FAK positively correlates with advanced stages of human colon cancer. Activated β4 integrin interacts with FAK and subsequently induces FAK phosphorylation at Tyr397. Furthermore, ablation of the β4 integrin/FAK complex and/or FAK activation impair colon cancer cell proliferation, anchorage-independent growth, and tumorigenicity. Our data indicate that the β4 integrin/FAK complex and subsequent FAK activation are essential regulators during the tumorigenicity of colon cancer, and we suggest an alternative strategy for colon cancer therapy.

NDRG4, a novel candidate tumor suppressor, is a predictor of overall survival of colorectal cancer patients

The role of NDRG4 in human malignancies is largely unknown. We investigated the role of NDRG4 protein in colorectal cancer and its prognostic value in a hospital-based retrospective training cohort of 272 patients and a prospective validation cohort of 708 patients were. Cell line was transfected with an NDRG4 expression construct to confirm the suppression of PI3K-AKT activity by NDRG4. Appropriate statistical methods were utilized for analysis. Results showed that NDRG4 protein expression was significantly decreased from normal mucosa, chronic colitis, ulcerative colitis, atypical hyperplasia to colorectal cancer. Significant negative correlations were found between NDRG4 staining and p-AKT. Patients with positive NDRG4 staining had favorable survival in both study cohorts. In multivariate analysis, NDRG4 staining proved to be an independent predictor of overall survival. Moreover, the prognostic role of NDRG4 was stratified by p-AKT. Overexpression of NDRG4 in colorectal cancer cell can significantly suppress PI3K-AKT activity, even after EGF stimulation. These results indicated NDRG4 protein expression was decreased in colorectal cancer. It may play its tumor suppressive role in carcinogenesis and progression through attenuation of PI3K-AKT activity. Therefore, high risk colorectal cancer patients could be better identified based on the combination of NDRG4 and PI3K-AKT activity.

Mechanosensitive caveolin-1 activation-induced PI3K/Akt/mTOR signaling pathway promotes breast cancer motility, invadopodia formation and metastasis in vivo

Cancer cells are subjected to fluid shear stress during passage through the venous and lymphatic system. Caveolin-1 (Cav-1), a principal structural component of caveolar membrane domains, contributes to cancer development but its mechanobiological roles under low shear stress (LSS) conditions remain largely unknown. Here, we identified Cav-1 is mechanosensitive to LSS exposure, and its activation-induced PI3K/Akt/mTOR signaling promotes motility, invadopodia formation and metastasis of breast carcinoma MDA-MB-231 cells. Application of LSS (1.8 and 4.0 dynes/cm2) to MDA-MB-231 cells significantly increased the cell motility, invadopodia formation, MT1-MMP expression, ECM degradation, and also induced a sustained activation of Cav-1 and PI3K/Akt/mTOR signaling cascades. Methyl-β-cyclodextrin-caused caveolae destruction markedly decreased LSS-induced activation of both Cav-1 and PI3K/Akt/mTOR, leading to suppress MT1-MMP expression, inhibit invadopodia formation and ECM degradation, suggesting that caveolae integrity also involved in metastasis. Immunocytochemical assay showed that LSS induces the Cav-1 clustering in lipid rafts and co-localization of Cav-1 and MT1-MMP on invadopodia. Immunofluorescence confocal analysis demonstrated that Cav-1 activation were required for the acquisition of a polarized phenotype in MDA-MB-231 cells. Finally, Cav-1 knockdown significantly suppressed tumor colonization in the lungs and distant metastases in animal models. Our findings highlight the importance of Cav-1 in hematogenous metastasis, and provide new insights into the underlying mechanisms of mechanotransduction induced by LSS.