Progress in researches about focal adhesion kinase in gastrointestinal tract

Design, synthesis, and biological evaluation of diaminopyrimidine derivatives as novel focal adhesion kinase inhibitors

Focal adhesion kinase (FAK) is a cytoplasmic non-receptor protein tyrosine kinase that belongs to the family of focal adhesion complexes and is responsible for the development of various tumors. Herein, 24 diaminopyrimidine derivatives were designed and synthesized based on TAE-226. Several compounds with good activity were further evaluated regarding their antiproliferative activities against two cancer cells with high FAK expression. Compound A12 showed potent anticancer activity against A549 and MDA-MB-231 cell lines with IC50 values of 130 nM and 94 nM, respectively. In vitro metabolic stability and cytochrome P450 (CYP) inhibition assays showed that A12 exhibited favorable stability and weak inhibitory activity on CYP isoforms. Preliminary evaluation of kinase selectivity showed that A12 was a multi-kinase inhibitor. The acute toxicity in vivo indicated that A12 possessed acceptable safety. Compound A12 was also selected for molecular docking studies and the prediction of molecular properties and drug-like properties. These results indicated that compound A12 could be used as a potential lead compound targeting FAK for further development.

Drug Discovery Targeting Focal Adhesion Kinase (FAK) as a Promising Cancer Therapy

FAK is a nonreceptor intracellular tyrosine kinase which plays an important biological function. Many studies have found that FAK is overexpressed in many human cancer cell lines, which promotes tumor cell growth by controlling cell adhesion, migration, proliferation, and survival. Therefore, targeting FAK is considered to be a promising cancer therapy with small molecules. Many FAK inhibitors have been reported as anticancer agents with various mechanisms. Currently, six FAK inhibitors, including GSK-2256098 (Phase I), VS-6063 (Phase II), CEP-37440 (Phase I), VS-6062 (Phase I), VS-4718 (Phase I), and BI-853520 (Phase I) are undergoing clinical trials in different phases. Up to now, there have been many novel FAK inhibitors with anticancer activity reported by different research groups. In addition, FAK degraders have been successfully developed through “proteolysis targeting chimera” (PROTAC) technology, opening up a new way for FAK-targeted therapy. In this paper, the structure and biological function of FAK are reviewed, and we summarize the design, chemical types, and activity of FAK inhibitors according to the development of FAK drugs, which provided the reference for the discovery of new anticancer agents.

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.

Semisynthetic oleanane triterpenoids inhibit migration and invasion of human breast cancer cells through downregulated expression of the ITGB1/PTK2/PXN pathway

This paper reports a study on the role of two synthetic derivatives of oleanolic acid (OA), HIMOXOL and Br-HIMOLID, in the regulation of cell migration and invasion and the underlying molecular mechanisms of breast cancer cells. The effect of the compounds on four breast cancer cell lines (MCF7, MDA-MB-231, MDA-MB-468, and T-47D) and also on noncancerous breast cells, MCF-12A, was reported. The compounds had no effect on the migration of MCF-12A cells. However, both the derivatives revealed a higher cytotoxicity than the maternal compound OA, and in sub-cytotoxic concentrations, they decreased the migration of MCF7, MDA-MB-231, and MDA-MB-468 breast cancer cells and also the invasion of MCF7 and MDA-MB-231 cells; although, the derivatives had no effect on the migration and invasion of T-47D cells. Both the derivatives of OA inhibited the cell migratory and invasive abilities of breast cancer cells by downregulating the expressions of ITGB1, PTK2, and PXN genes and by decreasing the phosphorylation status and the level of its respective proteins (integrin β1, FAK, and paxillin, respectively). This study is the first to report the antimigratory and anti-invasive activities of HIMOXOL and Br-HIMOLID in breast cancer cells.

A novel role of sphingosine kinase-1 in the invasion and angiogenesis of VHL mutant clear cell renal cell carcinoma

Sphingosine kinase 1 (SK1), the enzyme responsible for sphingosine 1-phosphate (S1P) production, is overexpressed in many human solid tumors. However, its role in clear cell renal cell carcinoma (ccRCC) has not been described previously. ccRCC cases are usually associated with mutations in von Hippel-Lindau (VHL) and subsequent normoxic stabilization of hypoxia-inducible factor (HIF). We previously showed that HIF-2α up-regulates SK1 expression during hypoxia in glioma cells. Therefore, we hypothesized that the stabilized HIF in ccRCC cells will be associated with increased SK1 expression. Here, we demonstrate that SK1 is overexpressed in 786-0 renal carcinoma cells lacking functional VHL, with concomitant high S1P levels that appear to be HIF-2α mediated. Moreover, examining the TCGA RNA seq database shows that SK1 expression was ∼2.7-fold higher in solid tumor tissue from ccRCC patients, and this was associated with less survival. Knockdown of SK1 in 786-0 ccRCC cells had no effect on cell proliferation. On the other hand, this knockdown resulted in an ∼3.5-fold decrease in invasion, less phosphorylation of focal adhesion kinase (FAK), and an ∼2-fold decrease in angiogenesis. Moreover, S1P treatment of SK1 knockdown cells resulted in phosphorylation of FAK and invasion, and this was mediated by S1P receptor 2. These results suggest that higher SK1 and S1P levels in VHL-defective ccRCC could induce invasion in an autocrine manner and angiogenesis in a paracrine manner. Accordingly, targeting SK1 could reduce both the invasion and angiogenesis of ccRCC and therefore improve the survival rate of patients.

Research of shRNAmir inhibitory effects towards focal adhesion kinase expression in the treatment of gastric cancer

Gastric cancer is the fourth most common type of malignant tumor, with a poor prognosis. Focal adhesion kinase (FAK) mediates the crosslink of intracellular signaling networks, playing a key role in cell migration and invasion. The aim of the present study was to investigate the effects of FAK interference on the proliferation ability, invasion and metastasis of gastric cancer cells. The FAK-RNAi lentiviral vector was infected into SGC7901 gastric cancer cells in order to observe the in vivo situations of tumor growth and metastasis before and after the FAK interference. The growth of SGC7901 gastric cancer cells in the interference group was significantly inhibited compared with that of the negative control (P<0.05) and the blank control groups (P<0.05), and the FAK expression significantly decreased (P<0.05). The in vitro invasion and metastasis experiments showed that the cell invasion and metastasis abilities of the interference group significantly decreased when compared with those of the negative control (P<0.05) and blank control groups (P<0.05). In the nude mouse subcutaneous tumor transplantation model, the mean ± standard deviation tumor weight of the interference group (1.474±0.9840 g) was lower than that of the negative control (3.134±0.3299 g) and blank control (2.68±0.12 g) groups (P<0.05). In the nude mice, the liver and peritoneal metastasis rates of the interference group were significantly lower than those of the negative control (P<0.05) and the blank control groups (P<0.05), and the FAK mRNA of the interference group significantly reduced (P<0.05). In conclusion, FAK interference could effectively suppress the proliferation, invasion and metastasis of transfected SGC7901 gastric cancer cells, and could inhibit the growth and distant metastasis of gastric cancer in nude mice.

FRAS1 knockdown reduces A549 cells migration and invasion through downregulation of FAK signaling

Distal metastasis is the major cause of death for the vast majority of lung cancer patients. Many extracellular matrix (ECM)-related molecules are proposed to be associated with the migration and invasion of cancer cells. FRAS1 encodes an ECM protein, however, little is known about its function on tumorigenesis and metastasis of lung cancer. In this work, FRAS1 was silenced by shRNA in non-small cell lung cancer (NSCLC) A549 cell line. The capacities of A549 cells to migrate and invade were decreased markedly after FRAS1 knockdown. The shRNA knockdown of FRAS1 was found to be specific and had no effect on A549 cells proliferation. Western blot experiments demonstrated that FRAS1 knockdown inhibited FAK signaling but not Src signaling. Overall, we found that FRAS1 knockdown reduces A549 cells migration and invasion ability through downregulation of FAK signaling.

Sulindac modulates secreted protein expression from LIM1215 colon carcinoma cells prior to apoptosis

Colorectal cancer (CRC) is a major cause of mortality in Western populations. Growing evidence from human and rodent studies indicate that nonsteroidal anti-inflammatory drugs (NSAIDs) cause regression of existing colon tumors and act as effective chemopreventive agents in sporadic colon tumor formation. Although much is known about the action of the NSAID sulindac, especially its role in inducing apoptosis, mechanisms underlying these effects is poorly understood. In previous secretome-based proteomic studies using 2D-DIGE/MS and cytokine arrays we identified over 150 proteins released from the CRC cell line LIM1215 whose expression levels were dysregulated by treatment with 1mM sulindac over 16h; many of these proteins are implicated in molecular and cellular functions such as cell proliferation, differentiation, adhesion, angiogenesis and apoptosis (Ji et al., Proteomics Clin. Appl. 2009, 3, 433-451). We have extended these studies and describe here an improved protein/peptide separation strategy that facilitated the identification of 987 proteins and peptides released from LIM1215 cells following 1mM sulindac treatment for 8h preceding the onset of apoptosis. This peptidome separation strategy involved fractional centrifugal ultrafiltration of concentrated cell culture media (CM) using nominal molecular weight membrane filters (NMWL 30K, 3K and 1K). Proteins isolated in the >30K and 3-30K fractions were electrophoretically separated by SDS-PAGE and endogenous peptides in the 1-3K membrane filter were fractioned by RP-HPLC; isolated proteins and peptides were identified by nanoLC-MS-MS. Collectively, our data show that LIM1215 cells treated with 1mM sulindac for 8h secrete decreased levels of proteins associated with extracellular matrix remodeling (e.g., collagens, perlecan, syndecans, filamins, dyneins, metalloproteinases and endopeptidases), cell adhesion (e.g., cadherins, integrins, laminins) and mucosal maintenance (e.g., glycoprotein 340 and mucins 5AC, 6, and 13). A salient finding of this study was the increased proteolysis of cell surface proteins following treatment with sulindac for 8h (40% higher than from untreated LIM1215 cells); several of these endogenous peptides contained C-terminal amino acids from transmembrane domains indicative of regulated intramembrane proteolysis (RIP). Taken together these results indicate that during the early-stage onset of sulindac-induced apoptosis (evidenced by increased annexin V binding, dephosphorylation of focal adhesion kinase (FAK), and cleavage of caspase-3), 1mM sulindac treatment of LIM1215 cells results in decreased expression of secreted proteins implicated in ECM remodeling, mucosal maintenance and cell-cell-adhesion. This article is part of a Special Issue entitled: An Updated Secretome.

Nivalenol and deoxynivalenol affect rat intestinal epithelial cells: a concentration related study

The integrity of the gastrointestinal tract represents a crucial first level defence against ingested toxins. Among them, Nivalenol is a trichotecenes mycotoxin frequently found on cereals and processed grains; when it contaminates human food and animal feed it is often associated with another widespread contaminant, Deoxynivalenol. Following their ingestion, intestinal epithelial cells are exposed to concentrations of these trichothecenes high enough to cause mycotoxicosis. In this study we have investigated the effects of Nivalenol and Deoxynivalenol on intestinal cells in an in vitro model system utilizing the non-tumorigenic rat intestinal epithelial cell line IEC-6. Both Nivalenol and Deoxynivalenol (5-80 µM) significantly affected IEC-6 viability through a pro-apoptotic process which mainly involved the following steps: (i) Bax induction; (ii) Bcl-2 inhibition, and (iii) caspase-3 activation. Moreover, treatment with Nivalenol produced a significant cell cycle arrest of IEC-6 cells, primarily at the G(0)/G(1) interphase and in the S phase, with a concomitant reduction in the fraction of cells in G(2). Interestingly, when administered at lower concentrations (0.1-2.5 µM), both Nivalenol and Deoxynivalenol affected epithelial cell migration (restitution), representing the initial step in gastrointestinal wound healing in the gut. This reduced motility was associated with significant remodelling of the actin cytoskeleton, and changes in expression of connexin-43 and focal adhesion kinase. The concentration range of Nivalenol or Deoxynivalenol we have tested is comparable with the mean estimated daily intake of consumers eating contaminated food. Thus, our results further highlight the risks associated with intake of even low levels of these toxins.

Sphingosine kinase 1 promotes tumor progression and confers malignancy phenotypes of colon cancer by regulating the focal adhesion kinase pathway and adhesion molecules

Studies suggest a tumor-promoting function of sphingosine kinase 1 (SphK1) in some types of human tumors, however, its effect on colon cancer is still unclear. The aims of this study were to investigate the roles of SphK1 in the progression and tumor cell phenotypic changes in colon cancer. Moreover, the focal adhesion kinase (FAK) pathway and the expression of intercellular adhesion molecule‑1 (ICAM‑1) and vascular cell adhesion molecule‑1 (VCAM‑1) were detected to explore the mechanisms of SphK1 action. In this study, the expression of SphK1, FAK and phospho-FAK (p-FAK) was analyzed in 66 surgical specimens of primary colon cancer and matched adjacent normal tissues by immunohistochemistry and western blotting. In addition, N,N-dimethylsphingosine (DMS), SphK1 DNA and shRNA transfection were used to regulate the expression and activity of SphK1 in the LOVO colon cancer cell line. Tumor cell phenotypic changes were analyzed by cell viability, invasion and apoptosis assays. Results showed that the expression of SphK1, FAK and p-FAK in colon cancer tissues were significantly stronger compared to those in matched normal tissues. There was a close correlation between the expression of SphK1 and FAK or p-FAK and the co-expression of SphK1, FAK and p-FAK significantly associated with histological grade, Dukes' stage, lymph node metastasis and distant metastasis. Overexpression of SphK1 after DNA transfection enhanced tumor cell viability and invasiveness, but suppressed cell apoptosis. In contrast, suppression of SphK1 by DMS and shRNA reduced tumor cell viability and invasiveness, but promoted cell apoptosis. The expression of FAK, p-FAK, ICAM-1 and VCAM-1 in LOVO cells were increased with the overexpression of SphK1 but decreased with the suppression of SphK1. These findings indicate that SphK1 regulates tumor cell proliferation, apoptosis and invasion, which ultimately contributes to tumor progression and malignancy phenotype in colon cancer. FAK pathway, ICAM-1 and VCAM-1 may play critical roles in this SphK1‑mediated effect.

FAK regulates intestinal epithelial cell survival and proliferation during mucosal wound healing

Background

Following damage to the intestinal epithelium, restoration of epithelial barrier integrity is triggered by a robust proliferative response. In other tissues, focal adhesion kinase (FAK) regulates many of the cellular processes that are critical for epithelial homeostasis and restitution, including cell migration, proliferation and survival. However, few studies to date have determined how FAK contributes to mucosal wound healing in vivo.

Methodology and Principal Findings

To examine the role of FAK in intestinal epithelial homeostasis and during injury, we generated intestinal epithelium (IE)-specific conditional FAK knockout mice. Colitis was induced with dextran-sulfate-sodium (DSS) and intestinal tissues were analyzed by immunohistochemistry and immunoblotting. While intestinal development occurred normally in mice lacking FAK, FAK-deficient animals were profoundly susceptible to colitis. The loss of epithelial FAK resulted in elevated p53 expression and an increased sensitivity to apoptosis, coincident with a failure to upregulate epithelial cell proliferation. FAK has been reported to function as a mechanosensor, inducing cyclin D1 expression and promoting cell cycle progression under conditions in which tissue/matrix stiffness is increased. Collagen deposition, a hallmark of inflammatory injury resulting in increased tissue rigidity, was observed in control and FAK knockout mice during colitis. Despite this fibrotic response, the colonic epithelium in FAK-deficient mice exhibited significantly reduced cyclin D1 expression, suggesting that proliferation is uncoupled from fibrosis in the absence of FAK. In support of this hypothesis, proliferation of Caco-2 cells increased proportionally with matrix stiffness in vitro only under conditions of normal FAK expression; FAK depleted cells exhibited reduced proliferation concomitant with attenuated cyclin D1 expression.

Conclusions

In the colon, FAK functions as a regulator of epithelial cell survival and proliferation under conditions of mucosal injury and a mechanosensor of tissue compliance, inducing repair-driven proliferation in the colonic epithelium through upregulation of cyclin D1.

The bovine milk proteome: cherishing, nourishing and fostering molecular complexity. An interactomics and functional overview

Bovine milk represents an essential source of nutrients for lactating calves and a key raw material for human food preparations. A wealth of data are present in the literature dealing with massive proteomic analyses of milk fractions and independent targeted studies on specific groups of proteins, such as caseins, globulins, hormones and cytokines. In this study, we merged data from previous investigations to compile an exhaustive list of 573 non-redundant annotated protein entries. This inventory was exploited for integrated in silico studies, including functional GO term enrichment (FatiGO/Babelomics), multiple pathway and network analyses. As expected, most of the milk proteins were grouped under pathways/networks/ontologies referring to nutrient transport, lipid metabolism and objectification of the immune system response. Notably enough, another functional family was observed as the most statistically significant one, which included proteins involved in the induction of cellular proliferation processes as well as in anatomical and haematological system development. Although the latter function for bovine milk proteins has long been postulated, studies reported so far mainly focused on a handful of molecules and missed the whole overview resulting from an integrated holistic analysis. A preliminary map of the bovine milk proteins interactome was also built up, which will be refined in future as result of the widespread use of quantitative methods in protein interaction studies and consequent reduction of false-positives within associated databases.