Focal Adhesion Kinase Expression Research Articles

Abstract 965: The role of LOX-mediated FAK phosphorylation in osteosarcoma metastasis

Abstract Despite the use of chemotherapy and surgery, the development of metastasis remains to be the leading cause of death in patients with osteosarcoma. LOX encodes for lysyl oxidase, which is an enigmatic molecule in cancer by acting as a tumor suppressor in certain tumors, but a metastatic promoter in other tumors. To investigate the function of LOX, we generated LOX overexpression mutants in two osteosarcoma cell lines and showed that higher LOX expression promoted tumor cell proliferation and invasiveness. Using an orthotopic xenograft mouse model, we further showed that osteosarcoma cells with higher LOX expression produced a higher number of mice with pulmonary metastases than the parental cell line (n=9). To characterize the mechanism of LOX-mediated metastasis, we examined the protein expression of a panel of potential downstream targets. The results demonstrated that phospho-FAK (focal adhesion kinase) expression was increased in the LOX-overexpression mutant relative to the parental cell line. Using a small molecule inhibitor of FAK, we showed that it significantly reduced the LOX-mediated metastasis in the orthotopic xenograft model. To demonstrate the clinical significance of our findings, we analyzed the expression profiling and RNAseq datasets recently generated from the TARGET osteosarcoma study. A Kaplan-Meier analysis showed that a higher level of LOX expression significantly correlated with a poor outcome (p < 0.05) and a multivariate analysis indicated LOX remained to be significant after controlling for initial metastatic status. In addition, we have previously shown that p27 is frequently mislocalized in the cytoplasm of osteosarcoma cells and drives the development of metastasis through interacting with the PAK1-mediated actin cytoskeleton network. Our results showed that the expression of LOX was upregulated in p27-mislocalized osteosarcoma cell lines with high metastatic potential. A tissue microarray analysis showed that cytoplasmic p27 expression significantly correlated with LOX expression (p = 0.003). Together, our findings suggest that a novel link between p27 mislocalization and LOX expression. LOX plays a pivotal role in osteosarcoma metastasis by upregulating FAK phosphorylation. FAK inhibition is a potential therapeutic strategy to reduce the development of metastasis in osteosarcoma with LOX overexpression. Citation Format: Xiang Chen, John M. Hicks, Poonam Sarkar, Waleed M. Gaber, Tsz-Kwong MAN. The role of LOX-mediated FAK phosphorylation in osteosarcoma metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 965.

Combinatorial Inhibition of Focal Adhesion Kinase and BCL-2 in AML

Focal adhesion kinase (FAK), activated by integrins and cytokines, promotes cell growth, migration and metastasis. We previously reported that a selective FAK inhibitor, VS-4718, inhibited cell growth and induced cell death in leukemia cell lines in vitro, effectively reduced leukemia burden in peripheral blood and tissues including bone marrow, spleen, liver and lung, and significantly prolonged survival time in a human xenograft murine model (Carter BZ et al., MCT, 2017), 16(6):1133).Although BCL-2 inhibition by the BCL-2 inhibitor ABT-199 (Venetoclax) has demonstrated antileukemia activities, an acquired drug resistance frequently ensues. When combined with ABT-199, VS-4718 significantly potentiated ABT-199-induced apoptosis in AML cell lines and primary AML cells. VS-4718 treatment of Molm14 AML cells decreased levels of p-STAT5, MCL-1, and BCL-XL (Wang et al., ASH 2016) that play important roles in the acquired resistance to ABT-199.To further examine the effect of VS-4718 as a single agent and in combination with ABT-199 on primary AML cells in vivo, we generated patient-derived xenografts (PDX) from AML patient bone marrow cells expanded in NSGS (NOD-SCID IL2Rgnull-3/GM/SF, NSG-SGM3) mice. The xenograft used AML cells from a patient who had failed multiple chemotherapies and had NPM1, FLT3-ITD, TET2, DNMT3A, and WT1 gene mutations and a complex karyotype. The combination of VS-4718 and ABT-199 synergistically killed the PDX cells in vitro even under MSC co-culture conditions. Once PDX cells were engrafted into NSGS mice, animals were randomized into 4 groups (N=10/group) and treated with vehicle, VS-4718 (75 mg/kg, twice daily), ABT-199 (100 mg/kg, once per day), or the combination via oral gavage for 29 days. We observed that ABT-199 had a stronger anti-leukemic effect on peripheral blood than on tissue-resident cells, while VS-4718 was more effective in tissues. At the end of the treatments, VS-4718 significantly reduced circulating human CD45+ cells (P=0.0003), and ABT-199 alone (P=5.90E-07) and the ABT-199/VS-4718 combination (P=5.38E-07) were ever more effective. VS-4718 alone or in combination with ABT-199 reduced leukemia burden in spleen and liver and effectively reduced splenomegaly, while ABT-199 alone did not. VS-4718-treated mice survived significantly longer than the untreated controls (median survival 72 vs. 36 days, P=0.0002), while ABT-199 did not prolong survival (median survival 35 days). Also, the combination of VS-4718 with ABT-199 significantly prolonged survival (median survival 65.5 days, P=0.011 vs. control and P=0.0072 vs. ABT-199). No statistical difference in survival was found between VS-4718 and the combination treatment groups (P=0.33) (Fig. 1). All the mice had large spleen at death except the combination group: the 1st dead mouse had small and the 2nd to 4th ones had slightly enlarged spleen and only the last two had large spleen as others suggesting that additional reasons such as toxicity at the dose used may have contributed to the death of the 1st 4 mice in the combination group, hence shortened the median survival in this group.We determined expression of FAK and BCL-2 family proteins in cells from mouse spleens at the end of treatment and found that the combination of VS-4718 and ABT-199 decreased protein levels of FAK. Consistent with our in vitro results, the increased level of MCL-1 by ABT-199 was antagonized by the combination with VS-4718 in vivo suggesting the combination potentially be more effective.Conclusions: These results suggest a potential clinical benefit of combining a FAK inhibitor with Venetoclax for patients with AML. [Display omitted] DisclosuresPachter:Verastem, Inc.: Employment. Weaver:Verastem, Inc.: Employment. Carter:Daiichi Sankyo: Research Funding; novartis: Research Funding.

Pro-fibrotic phenotype of bone marrow stromal cells in Modic type 1 changes.

Modic type 1 changes (MC1) are painful vertebral bone marrow lesions frequently found in patients suffering from chronic low-back pain. Marrow fibrosis is a hallmark of MC1. Bone marrow stromal cells (BMSCs) are key players in other fibrotic bone marrow pathologies, yet their role in MC1 is unknown. The present study aimed to characterise MC1 BMSCs and hypothesised a pro-fibrotic role of BMSCs in MC1. BMSCs were isolated from patients undergoing lumbar spinal fusion from MC1 and adjacent control vertebrae. Frequency of colony-forming unit fibroblast (CFU-F), expression of stem cell surface markers, differentiation capacity, transcriptome, matrix adhesion, cell contractility as well as expression of pro-collagen type I alpha 1, α-smooth muscle actin, integrins and focal adhesion kinase (FAK) were compared. More CFU-F and increased expression of C-X-C-motif-chemokine 12 were found in MC1 BMSCs, possibly indicating overrepresentation of a perisinusoidal BMSC population. RNA sequencing analysis showed enrichment in extracellular matrix proteins and fibrosis-related signalling genes. Increases in pro-collagen type I alpha 1 expression, cell adhesion, cell contractility and phosphorylation of FAK provided further evidence for their pro-fibrotic phenotype. Moreover, a leptin receptor high expressing (LEPRhigh) BMSC population was identified that differentiated under transforming growth factor beta 1 stimulation into myofibroblasts in MC1 but not in control BMSCs. In conclusion, pro-fibrotic changes in MC1 BMSCs and a LEPRhigh MC1 BMSC subpopulation susceptible to myofibroblast differentiation were found. Fibrosis is a hallmark of MC1 and a potential therapeutic target. A causal link between the pro-fibrotic phenotype and clinical characteristics needs to be demonstrated.

Development of a Rapid-Onset, Acid-Labile Linkage Polyplex-Mixed Micellar System for Anticancer Therapy.

In the treatment of cancers, small interfering ribonucleic acids (siRNAs) are delivered into cells to inhibit the oncogenic protein’s expression; however, polyanions, hydrophilicity, and rapid degradations in blood, endosomal or secondary lysosomal degradation hamper clinal applications. In this study, we first synthesized and characterized two copolymers: methoxy poly(ethylene glycol)-b-poly(2-hydroxy methacrylate-ketal-pyridoxal) and methoxy poly(ethylene glycol)-b-poly(methacrylic acid-co-histidine). Afterwards, we assembled two polymers with the focal adhesion kinase (FAK) siRNA, forming polyplex-mixed micelles for the treatment of the human colon cancer cell line HCT116. In terms of the physiological condition, the cationic pyridoxal molecules that were conjugated on the copolymer with ketal bonds could electrostatically attract the siRNA. Additionally, the pyridoxal could form a hydrophobic core together with the hydrophobic deprotonated histidine molecules in the other copolymer and the hydrophilic polyethylene glycol (PEG) shell to protect the siRNA. In an acidic condition, the pyridoxal would be cleaved from the polymers due to the breakage of the ketal bonds and the histidine molecules can simultaneously be protonated, resulting in the endosome/lysosome escape effect. On the basis of our results, the two copolymers were successfully prepared and the pyridoxal derivatives were identified to be able to carry the siRNA and be cleavable by the copolymers in an acidic solution. Polyplex-mixed micelles were prepared, and the micellar structures were identified. The endosome escape behavior was observed using a confocal laser scanning microscopy (CLSM). The FAK expression was therefore reduced, and the cytotoxicity of siRNA toward human colon cancer cells was exhibited, rapidly in 24 h. This exceptional anticancer efficiency suggests the potential of the pH-sensitive polyplex-mixed micellar system in siRNA delivery.

FAK inhibition alone or in combination with adjuvant therapies reduces cancer stem cell activity

Cancer stem-like cells (CSC) contribute to therapy resistance and recurrence. Focal adhesion kinase (FAK) has a role in CSC regulation. We determined the effect of FAK inhibition on breast CSC activity alone and in combination with adjuvant therapies. FAK inhibition reduced CSC activity and self-renewal across all molecular subtypes in primary human breast cancer samples. Combined FAK and paclitaxel reduced self-renewal in triple negative cell lines. An invasive breast cancer cohort confirmed high FAK expression correlated with increased risk of recurrence and reduced survival. Co-expression of FAK and CSC markers was associated with the poorest prognosis, identifying a high-risk patient population. Combined FAK and paclitaxel treatment reduced tumour size, Ki67, ex-vivo mammospheres and ALDH+ expression in two triple negative patient derived Xenograft (PDX) models. Combined treatment reduced tumour initiation in a limiting dilution re-implantation PDX model. Combined FAK inhibition with adjuvant therapy has the potential to improve breast cancer survival.

Induction of cyclophilin A by influenza A virus infection facilitates group A Streptococcus coinfection.

During influenza A epidemics, bacterial coinfection is a major cause of increased morbidity and mortality. However, the roles of host factors in regulating influenza A virus (IAV)-triggered bacterial coinfection remain elusive. Cyclophilin A (CypA) is an important regulator of infection and immunity. Here, we show that IAV-induced CypA expression facilitates group A Streptococcus (GAS) coinfection both invitro and invivo. Upon IAV infection, CypA interacts with focal adhesion kinase (FAK) and inhibited E3 ligase cCbl-mediated, K48-linked ubiquitination of FAK, which positively regulates integrin α5 expression and actin rearrangement via the FAK/Akt signaling pathway to facilitate GAS colonization and invasion. Notably, CypA deficiency or inhibition by cyclosporine A significantly inhibits IAV-triggered GAS coinfection in mice. Collectively, thesefindings reveal that CypA is critical for GAS infection, and induction of CypA expression is another way for IAV to promote bacterial coinfection, suggesting that CypA is a promising therapeutic target for the secondary bacterial infection.

Exogenous Cell Surface Modification with Cell Penetrating Peptide-Conjugated Lipids Causes Spontaneous Cell Adhesion.

The technique of cell patterning on a substrate is of great importance for platforms in cell-based assays. Chemical treatment of the substrate is commonly performed for cell patterning using cationic polymers, extracellular matrices, and antibodies. However, cell patterning could be easier if there is an approach to immobilize cells without treating the substrate surface. We previously reported that cell adhesion could be induced by the modification of the cellular surface with a cell-penetrating peptide (CPP)-conjugated poly(ethylene glycol)-phospholipid (CPP-PEG-lipid). This approach does not require chemical modification of the substrate surface, such as polystyrene or glass, and can be used for the cell patterning of floating cells. Here, we aimed to study the mechanism of induced cell adhesion using a representative CPP, Tat peptide (Tat-PEG-lipid). We found that cell adhesion was induced via electrostatic interactions between the Tat peptide and the substrate surface, which could be induced more efficiently by increasing the molecular weight of PEG together with CPPs but not with cationic peptides. The excluded volume effect between neighboring PEG chains could stretch the cell shape better than PEG with lower molecular weight, allowing the cell to spread firmly. In addition, Tat-PEG-lipid did not activate actin filament formation and did not influence the expression of focal adhesion kinase. Thus, the induced cell adhesion by CPP-PEG-lipid did not affect internal cell signaling.

Impact of Implant Surface Material and Microscale Roughness on the Initial Attachment and Proliferation of Primary Human Gingival Fibroblasts.

Simple SummaryIn recent years, zirconia dental implant systems, also known as “ceramic implants”, became an alternative to the commonly used titanium implants. The clinical success of dental implants depends on several factors, particularly on the soft tissue formation around the implant abutment, but the implant surfaces, which at most support this process, are still to be found. In the present study, we cultured human gingival cells on surfaces that were made from either titanium or zirconia. These surfaces were differently treated and, subsequently, had different roughness: some surfaces were machined and smooth, whereas other surfaces were sand-blasted and rough. The cells ability to attach and grow was slightly decreased by rougher surfaces, whereas no effect of implant material was observed. Furthermore, the expression of some proteins mediating cell attachment to the surface was strongly affected by the roughness and only marginally by the implant material. We concluded that the behavior of gingival cells is primarily influenced by surface roughness, whereas no apparent advantage of either material could be observed. This suggests the importance of surface makeup in relation to how soft tissue healing around the implant is promoted and might provide new approaches for future research.Due to the rising demand for zirconia (Zr) based implant systems, it is important to understand the impact of Zr and titanium (Ti) implants and particularly their topography on soft tissue healing. As human gingival fibroblasts (hGFs) are the predominant cells in peri-implant soft tissue, we focused on examining the effect of implant material and surface roughness on hGFs’ initial attachment, growth and the expression of proteins involved in the focal adhesion. hGFs isolated from eight healthy donors were cultured on the following surfaces: smooth titanium machined surface (TiM), smooth zirconia machined surface (ZrM), moderately rough titanium surface (SLA), or moderately rough zirconia surface (ZLA) for up to 14 days. The initial attachment of hGFs was evaluated by scanning electron microscopy. Cell proliferation/viability was assessed by cell counting kit 8. Focal adhesion and cytoskeleton were visualized by a focal adhesion staining kit. The gene expression of focal adhesion kinase (FAK), α-smooth muscle actin (α-SMA), and integrin subunits ITG-β1, ITG-β4, ITG-α4, ITG-α5, ITG-α6, was evaluated by qPCR. Cell proliferation/viability was slightly decreased by moderately rough surfaces, whereas no effect of surface material was observed. Cell morphology was strikingly different between differently treated surfaces: on machined surfaces, cells had elongated morphology and were attached along the grooves, whereas on moderately rough surfaces, cells were randomly attached. Surface roughness had a more pronounced effect on the gene expression compared to the surface material. The expression of FAK, α-SMA, ITG-β4, ITG-α5, and ITG-α6 was enhanced by moderately rough surfaces compared to smooth surfaces. Within the limitations of this in vitro study, it can be concluded that the behavior of primary hGFs is primarily affected by surface structure, whereas no apparent advantage of Zr over Ti could be observed.

Abnormal expression of FAK and paxillin correlates with oral cancer invasion and metastasis.

Globally, the tenth most common cancer is the oral squamous cell carcinoma (OSCC) and the treatment strategy for improving of OSCC patients survival rate still remains a challenging one. Aberrant regulation of cell to extracellular matrix protein interactions leads to progression of human cancers. The focal adhesion kinase (FAK) and its downstream target paxillin have been implicated in cancer growth, migration, invasion and metastasis of different cancers. However, the clinical significance of FAK and paxillin in OSCC is not well characterized so far. In the present work, we showed that relative mRNA and protein expressions of FAK and paxillin are significantly higher in side population (SP) cells of OSCC cell line SCC-55. Concomitantly, the matrix metalloproteinase-11 (MMP-11) level is also significantly elevated in SP cells. The enhanced expression of paxillin is strongly correlated with increased chemoresistance, proliferation rate, migration and invasion potential of SP cells. In addition, inhibition of paxillin expression by RNAi makes SP cells more sensitive to chemotherapy drugs. Therefore, our results suggest that paxillin over expression might play a significant role in cancer progression, invasion and chemoresistance of OSCC.

Programming Colloidal Self-Assembled Patterns (cSAPs) into Thermo-Responsible Hybrid Surfaces for Controlling Human Stem Cells and Macrophages.

Hybrid surfaces with tunable topography, chemistry, and stiffness have potential to rebuild native extracellular matrix (ECM) and manipulate cell behavior in vitro. However, the fabrication of controllable hybrid surfaces is still challenging. In this study, colloidal self-assembly technology was used to program particles into highly ordered structures with hybrid chemistry and stiffness at biointerfaces. These colloidal self-assembled patterns (cSAPs), including unary, binary, and ternary cSAPs, composed of silicon (Si), polystyrene (PS), and/or poly(N-isopropylacrylamide) (pNIPAM) nanogels (PNGs), were fabricated using either coassembly or layer-by-layer (LBL) methods. The selected binary cSAPs (i.e., PS/PNG and PNG/PS) have a tunable surface topography and wettability between 25 and 37 °C; thus, they can be used as dynamic cell culture substrates. Human adipose-derived mesenchymal stem cells (hASCs), bone marrow-derived mesenchymal stem cells (hBMSCs), and macrophages (THP-1) were investigated on these hybrid cSAPs under a static or dynamic system. The results showed that hybrid cSAPs significantly influenced the focal adhesions, cell morphology, cell migration, and gene expressions of stem cells. In general, stem cells had more vinculin puncta, smaller spreading size, and faster migration speed than the TCPS control. Hybrid cSAPs up-regulated gene expressions of focal adhesion kinase (FAK) and chondrocytes (AGG and SOX9) under static culture, while they also up-regulated osteocytes (COL1 and RUNX2) under dynamic culture. THP-1 macrophages were at M0 state on all cSAPs under static culture. However, cells became sensitive under dynamic culture. For example, some M1 genes (i.e., IL6, CD68, and TNFα) and M2 genes (i.e., IL10 and CD206) were down-regulated, while other M1 genes (i.e., IL1β) and M2 genes (i.e., TGF-β and IL1ra) were up-regulated, depending on the particle combinations. In conclusion, new hybrid cSAPs with thermoresponsive surface properties are versatile materials for stem cells and macrophages manipulation.

Maintenance of HDACs and H3K9me3 Prevents Arterial Flow-Induced Venous Endothelial Damage.

The transition of flow microenvironments from veins to arteries in vein graft surgery induces “peel-off” of venous endothelial cells (vECs) and results in restenosis. Recently, arterial laminar shear stress (ALS) and oscillatory shear stress (OS) have been shown to affect the cell cycle and inflammation through epigenetic controls such as histone deacetylation by histone deacetylases (HDACs) and trimethylation on lysine 9 of histone 3 (H3K9me3) in arterial ECs. However, the roles of H3K9me3 and HDAC in vEC damage under ALS are not known. We hypothesized that the different responses of HDACs and H3K9me3 might cause vEC damage under the transition of venous flow to arterial flow. We found that arterial ECs showed high expression of H3K9me3 protein and were retained in the G0 phase of the cell cycle after being subjected to ALS. vECs became round under ALS with a decrease in the expression of H3K9me3, HDAC3, and HDAC5, and an increase in the expression of vascular cell adhesion molecule 1 (VCAM-1). Inhibition of HDACs activity by a specific inhibitor, phenylbutyrate, in arterial ECs caused similar ALS-induced inflammation and cell loss as observed in vECs. Activation of HDACs and H3K9me3 by ITSA-1, an HDAC activator, could prevent ALS-induced peel-off and reduced VCAM-1 expression in vECs. Moreover, shear stress modulates EC morphology by the regulation of focal adhesion kinase (FAK) expression. ITSA-1 or EGF could increase phosphorylated (p)-FAK expression in vECs under ALS. We found that perturbation of the activity of p-FAK and increase in p-FAK expression restored ALS-induced H3K9me3 expression in vECs. Hence, the abnormal mechanoresponses of H3K9me3 and HDAC in vECs after being subjected to ALS could be reversed by ITSA-1 or EGF treatment: this offers a strategy to prevent vein graft failure.

Absence of progesterone receptor membrane component 1 reduces migration and metastasis of breast cancer

BackgroundProgesterone receptor membrane component 1 (Pgrmc1) is a non-classical progesterone receptor associated with the development of the mammary gland and xenograft-induced breast cancer. Importantly, Pgrmc1 is associated with the expression of estrogen receptor alpha and can be used for predicting the prognosis of breast cancer. Whether the genetic deletion of Pgrmc1 affects the progression of breast cancer is still unclear.MethodsWe used MMTV-PyMT transgenic mice that spontaneously develop breast tumors. In backcrossed FVB Pgrmc1 knockout (KO) mice, we monitored the development of the primary tumor and lung metastasis. In MCF-7 and MDA-MB-231 tumor cell lines, the migratory activity was evaluated after Pgrmc1 knockdown.ResultsThere was no significant difference in the development of breast cancer in terms of tumor size at 13 weeks of age between WT and Pgrmc1 KO mice. However, Pgrmc1 KO mice had a significantly longer survival duration compared with WT mice. Furthermore, Pgrmc1 KO mice exhibited a significantly lower degree of lung metastasis. Compared with those of WT mice, the tumors of Pgrmc1 KO mice had a low expression of focal adhesion kinase and epithelial–mesenchymal transition markers. PGRMC1 knockdown resulted in a significantly reduced migration rate in breast cancer cell lines.ConclusionsPgrmc1 KO mice with breast cancer had a prolonged survival, which was accompanied by a low degree of lung metastasis. PGRMC1 showed a significant role in the migration of breast cancer cells, and may serve as a potential therapeutic target in breast cancer.AYstNrTAYcCJz1LVvudn4eVideo

G9a Promotes Invasion and Metastasis of Non-Small Cell Lung Cancer through Enhancing Focal Adhesion Kinase Activation via NF-κB Signaling Pathway.

Potential roles of euchromatic histone methyltransferase 2 (EHMT2 or G9a) in invasion and metastasis are not well understood in non-small cell lung cancer (NSCLC). Here, we investigated the effect and underlying mechanisms of G9a and therapeutic implications of targeting G9a in the invasion and metastasis of NSCLC. Overexpression of G9a significantly enhanced in vitro proliferation and invasion, while knockdown of G9a drastically suppressed in vivo growth and metastasis of A549 and H1299 NSCLC cells. Knockdown or inhibition of G9a significantly decreased the expression of focal adhesion kinase (FAK) protein and activation of FAK pathway. In addition, defactinib, a potent FAK inhibitor, partially abolished the G9a-enhanced invasion in these NSCLC cells. Furthermore, targeting G9a was found to suppress NF-κB transcriptional activity in NSCLC cells through stabilizing NF-κB inhibitor alpha (IκBα), while an NF-κB inhibitor Parthenilide partially abolished the G9a-enhanced FAK activation, which suggests that G9a-enhanced invasion and activation of FAK is mediated by elevated NF-κB activity. Notably, a strong positive correlation between the IHC staining of G9a and phosphorylated FAK proteins was identified in H1299 xenografts and 159 cases of NSCLC tissues (R = 0.408). IMPLICATIONS: The findings of this study strongly demonstrate that G9a may promote invasion and metastasis of NSCLC cells by enhancing FAK signaling pathway via elevating NF-κB transcriptional activity, indicating potential significance and therapeutic implications of these pathways in the invasion and metastasis of NSCLCs that overexpress G9a protein.

Role of PTEN in FAK and α-SMA protein levels changes in human embryonic lung fibroblasts induced by silica

To investigate the roles of phosphatase and tensin homolog deleted on chromosome 10(PTEN) in focal adhesion kinase(FAK) and α-smooth muscle actin(α-SMA) protein levels changes in human embryonic lung fibroblasts(HELFs) induced by silica. The HELF cells were cultured in low serum medium containing 0, 25, 50, 100 and 200 μg/cm~2 silica for 24 hours, and the cell counting kit-8(CCK8) experiment was used to determine the appropriate dose of silica for stimulation. Meanwhile, the effect of different doses of silica on the morphology of HELFs was observed under inverted microscope. 50 μg/cm~2 silica solution was used to culture HELFs for 0, 1, 2, 4, 8, 12 and 24 hours(h), and the control group were used as the control group. In addition, Western blot was used to detect HELFs PTEN, p-PTEN, FAK, p-FAK and α-SMA protein levels at each culture time. Besides, HELFs were cultured with 2×10~(-3) mol/L PTEN inhibitor(VO-Ohpic) and/or silica for 24 h, including HELFs group, HELFs plus silica group, and HELFs plus silica plus VO-Ohpic group, and the FAK, p-FAK and α-SMA in each group were also detected by Western blot. With the increase of silica dose, HELFs viability firstly increased and then decreased, and the cell viability of 50 μg/cm~2 group(144. 91±5. 10) was significantly higher than that of 0 μg/cm~2 group(101. 23±6. 57)(P<0. 05). Compared with the control group of silica treated HELFs, the expression levels of PTEN and p-PTEN at 12 h and 24 h were significantly decreased(PTEN: 0. 44±0. 08 at 12 h, 0. 25±0. 02 at 24 h; p-PTEN: 0. 09±0. 01 at 12 h, 0. 01±0. 00 at 24 h; all P values<0. 05); whereas, FAK at 12 h(0. 92±0. 05) and 24 h(0. 89±0. 01), and p-FAK(0. 77±0. 02) and α-SMA at 24 h(1. 32±0. 01) were significantly increased(all P values<0. 05). The expression levels of FAK(0. 25±0. 03), p-FAK(0. 40±0. 02) and α-SMA(0. 36±0. 01) of HELFs plus silica plus VO-Ohpic group were significantly higher than those of HELFs plus silica group(P<0. 05). While silica induces HELFs FAK, p-FAK, and α-SMA increase, PTEN may downregulate FAK, p-FAK and α-SMA expression levels.

Focal Adhesion Kinase Fine Tunes Multifaced Signals toward Breast Cancer Progression.

Simple SummaryBreast cancer is the most common diagnosed malignancy and the main leading cause of tumor-related death among women worldwide. Thus, several studies have been carried out in order to identify valuable molecular biomarkers for the prognosis and prediction of therapeutic responses in breast tumor patients. Focal adhesion kinase (FAK) is a cytoplasmic non-receptor protein tyrosine kinase overexpressed in diverse tumors, including breast cancer. Here, we review previous evidence dealing with the role of FAK in the growth and metastatic features of breast tumors, its action as a driver of cancer stem cell phenotype and function as a mechanotransducer, and FAK activity within the breast tumor microenvironment and critical prognostic value of FAK expression in breast malignancy. In addition, we recapitulated the usefulness of FAK inhibitors in breast cancer treatment.Breast cancer represents the most common diagnosed malignancy and the main leading cause of tumor-related death among women worldwide. Therefore, several efforts have been made in order to identify valuable molecular biomarkers for the prognosis and prediction of therapeutic responses in breast tumor patients. In this context, emerging discoveries have indicated that focal adhesion kinase (FAK), a non-receptor tyrosine kinase, might represent a promising target involved in breast tumorigenesis. Of note, high FAK expression and activity have been tightly correlated with a poor clinical outcome and metastatic features in several tumors, including breast cancer. Recently, a role for the integrin-FAK signaling in mechanotransduction has been suggested and the function of FAK within the breast tumor microenvironment has been ascertained toward tumor angiogenesis and vascular permeability. FAK has been also involved in cancer stem cells (CSCs)-mediated initiation, maintenance and therapeutic responses of breast tumors. In addition, the potential of FAK to elicit breast tumor-promoting effects has been even associated with the capability to modulate immune responses. On the basis of these findings, several agents targeting FAK have been exploited in diverse preclinical tumor models. Here, we recapitulate the multifaceted action exerted by FAK and its prognostic significance in breast cancer. Moreover, we highlight the recent clinical evidence regarding the usefulness of FAK inhibitors in the treatment of breast tumors.

Carbon Ion Irradiation Enhances the Anti-tumor Efficiency in Tongue Squamous Cell Carcinoma via Modulating the FAK Signaling.

Oral cancer is a very aggressive disease with high rates of recurrence and metastasis. This study aimed at addressing how efficiently tongue cancer is suppressed after carbon ion irradiation. Here, the close relationship between upregulated expression of focal adhesion kinase (FAK) and high metastatic status in tongue squamous cell carcinoma patients was validated using bioinformatics and immunohistochemical analyses. Our data indicated that FAK suppression significantly enhanced the killing effect induced by irradiation in the tongue cancer cell line CAL27, as evidenced by increased apoptotic induction and reduced colony formation. More importantly, in FAK-deficient cells, carbon ion irradiation was shown to remarkably inhibit migration and invasion by delaying wound healing and slowing down motility. Further studies revealed that irradiation exposure caused disorganization of the actin cytoskeleton and reduced cell adhesive energy in FAK-deficient cells. Moreover, carbon ion treatment, in combination with FAK silencing, markedly blocked the phosphorylation levels of FAK, and paxillin, which partly contributed to the reduced motility of tongue squamous cell carcinoma CAL27 cells. Collectively, these results suggest that the prominent obstructing role of carbon ion irradiation in the growth inhibition and metastatic behavior of tumors, including attenuation of cell adhesiveness, motility, and invasiveness, could be distinctly modulated by FAK-mediated downstream pathways.

Actinobacillus pleuropneumoniae exotoxin ApxI induces cell death via attenuation of FAK through LFA-1

ApxI exotoxin is an important virulence factor derived from Actinobacillus pleuropneumoniae that causes pleuropneumonia in swine. Here, we investigate the role of lymphocyte function-associated antigen 1 (LFA-1, CD11a/CD18), a member of the β2 integrin family, and the involvement of the integrin signaling molecules focal adhesion kinase (FAK) and Akt in ApxI cytotoxicity. Using Western blot analysis, we found that ApxI downregulated the activity of FAK and Akt in porcine alveolar macrophages (AMs). Preincubation of porcine AMs with an antibody specific for porcine CD18 reduced ApxI-induced cytotoxicity as measured by a lactate dehydrogenase release assay and decreased ApxI-induced FAK and Akt attenuation, as shown by Western blot analysis. Pretreatment with the chemical compounds PMA and SC79, which activate FAK and Akt, respectively, failed to overcome the ApxI-induced attenuation of FAK and Akt and death of porcine AMs. Notably, the transfection experiments revealed that ectopic expression of porcine LFA-1 (pLFA-1) conferred susceptibility to ApxI in ApxI-insensitive cell lines, including human embryonic kidney 293T cells and FAK-deficient mouse embryonic fibroblasts (MEFs). Furthermore, ectopic expression of FAK significantly reduced ApxI cytotoxicity in pLFA-1-cotransfected FAK-deficient MEFs. These findings show for the first time that pLFA-1 renders cells susceptible to ApxI and ApxI-mediated attenuation of FAK activity via CD18, thereby contributing to subsequent cell death.

Effects of fluid shear stress on expression of focal adhesion kinase in MG-63 human osteoblast-like cells on different surface modification of titanium

ABSTRACT This study aimed to investigate the effect of fluid shear stress (FSS) on cell proliferation and expression of focal adhesion kinase (FAK) in MG-63 cells on different modified titanium surfaces. MG63 cells were cultured on three different surfaces: glass slide, polished treatment (PT) titanium surface and sandblasted/acid-etched surfaces (SLA) titanium surface. The surface topography and roughness were evaluated by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. The cells were subjected to FSS, and the cell appearance before and after the stress was evaluated. MTT assay was applied to estimate cell proliferation. The mRNA and protein levels of FAK were determined by qRT-PCR and western blotting. Titanium plates demonstrated different surface microtopography. Parameter Ra values of SLA group were around 3.4 µm, which was higher than PT group. Exposure to the FSS of 12 dynes/cm2 significantly induced positive upregulation of cellular proliferation and the expression of FAK, which were directly correlated with the duration of exposure and surface. Cells in SLA group were able to endurance the longtime of FSS, especially under the FSS of 16 dynes/cm2. SLA surface had a positive influence on the expression of FAK. Different surface modifications created different microtopography of titanium plates. Cell proliferation and the mRNA and protein expression of FAK were stimulated by FSS and regulated by a marked synergistic effect of surface topography and the level and duration of FSS.

Mechanism of lncRNA-SRLR induced invasion and metastasis in U2OS osteosarcoma cells

Objective: To explore the potential mechanism of sorafenib resistance associated long non-coding RNA (lncRNA-SRLR) promoted invasion and metastasis in U2OS osteosarcoma cells. Methods: We transfected U2OS cells with negative control lentivirus (LV-NC) or lncRNA-SRLR overexpressed lentivirus (LV-over/SRLR) particles. LV-NC and LV-over/SRLR stable transfected cells (U20S/NC and U20S/SRLR) were selected by primary cell culture medium containing puromycin. The mRNA expressions of lncRNA-SRLR and procollagen-lysine, procollagen-lysine 2-oxoglutarate 5-dioxygenase 2 (PLOD2) were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The effect of lncRNA-SRLR on the invasion of U2OS cells were determined by wound-healing assay and Transwell migration assay. The effect of SRLR on the interleukin-6 (IL-6) secretion of U2OS cells was evaluated by enzyme-linked immunosorbent assay (ELISA) analysis. The subcellular distribution of SRLR in U2OS cells was detected by fluorescence in situ hybridization (FISH) analysis.The expression of PLOD2 in cells was detected by immunofluorescence (IF). The expressions of PLOD2 and focal adhesion kinase (FAK)/signal transducer and activator of transcription 3 (STAT3) signal pathway related proteins in U2OS/NC and U2OS/SRLR cells were detected by western blotting. Results: qRT-PCR assay showed that mRNA expressions of lncRNA-SRLR and PLOD2 in U2OS/SRLR cells were (3 964.97±0.05) and (2.77±0.11), respectively, significantly higher than those in U2OS/NC cells (P<0.001 or P<0.01). The results of wound-healing and Transwell migration assay showed that over-expression of SRLR markedly promoted the invasion ability of U2OS cells (P<0.05). The result of ELISA analysis showed that the IL-6 secretions in U2OS/NC or U2OS/SRLR cells were (125.38±11.22) pg/ml or (119.97±13.43) pg/ml, without statistical significance (P>0.05). The subcellular distribution assay revealed that lncRNA-SRLR is predominately located in the nucleus. The result of IF showed that compared with U2OS/NC cells, the expression of PLOD2 was up-regulated in U2OS/SRLR cells. The result of western blotting showed that over-expression of SRLR significantly increased the expression levels of PLOD2, phosphorylation (p)-FAK and p-STAT3 in U2OS cells (P<0.01). Conclusion: lncRNA-SRLR promotes invasion and metastasis of osteosarcoma by activating PLOD2-FAK/STAT3 signal axis.

LncRNA EZR‑AS1 knockdown represses proliferation, migration and invasion of cSCC via the PI3K/AKT signaling pathway.

Although long non-coding RNAs (lncRNAs) have been implicated in various human cancer types, the role of lncRNA ezrin antisense RNA 1 (EZR-AS1) in cutaneous squamous cell carcinoma (cSCC) remains unclear. The present study aimed to investigate the effect of lncRNAEZR-AS1 on cSCC and identify the underlying molecular mechanisms. EZR-AS1 expression was measured in cSCC tissue and cells detected using reverse transcription-quantitative PCR. Gain-of-function assays were performed in A431 cells, which have a relatively low expression of EZR-AS1, while loss-of-function assays were performed in SCC13 and SCL-1 colon cancer cells, which have a relatively high expression of EZR-AS1. Cell viability, proliferation, migration, invasion and apoptosis were assessed using MTT, plate cloning, wound healing, Transwell and flow cytometry assays, respectively. EZR-AS1 mRNA expression levels were significantly upregulated in cSCC tissues and cells compared with adjacent healthy tissues and HaCaT cells, respectively. Compared with the small interfering RNA (si)-negative control (NC) group, si-EZR-AS1 significantly inhibited SCC13 and SCL-1 cell proliferation, migration and invasion, but promoted cell apoptosis. By contrast, compared with the pc-NC group, EZR-AS1 overexpression significantly enhanced A431 cell proliferation, migration and invasion, but inhibited cell apoptosis. Moreover, focal adhesion kinase (FAK) was identified as a target of EZR-AS1, and EZR-AS1 knockdown significantly decreased FAK expression compared with the si-NC group. Moreover, EZR-AS1 knockdown significantly downregulated the protein expression levels of phosphorylated (p)-PI3K/PI3K and p-AKT/AKT in cSCC cells compared with the si-NC group. The PI3K agonist 740Y-P significantly reversed si-EZR-AS1-mediated effects on SCC13 and SCL-1 cell proliferation, migration, invasion and apoptosis. In conclusion, the present study demonstrated that si-EZR-AS1 inhibited cSCC cell proliferation, migration and invasion, and promoted cell apoptosis, potentially via regulating the PI3K/AKT signaling pathway. Therefore, the present study provided novel insights into the diagnosis and treatment of cSCC.