Reduced expression of focal adhesion kinase in intrahepatic cholangiocarcinoma is associated with poor tumor differentiation

FAK/IL-8 axis promotes the proliferation and migration of gastric cancer cells

Gastric cancer (GC) is one of the most common malignancies in China and is associated with high mortality. The occurrence and development of gastric cancer are related to genetic and environmental factors. Focal adhesion kinase (FAK) is a cytoplasmic nonreceptor protein tyrosine kinase that is activated by the extracellular matrix and growth factors. FAK is highly expressed in cancer and promotes its development by regulating cancer cell proliferation, migration, and angiogenesis. The expression of IL-8 is increased in many types of malignant tumor cells and is linked to their proliferation, migration, invasion, angiogenesis, and EMT. In this study, we found FAK to be essential for the proliferation, migration, and peritoneal metastasis of gastric cancer cells. To examine the molecular regulatory mechanisms of FAK in the peritoneal dissemination of gastric cancer, we performed RNA-seq analysis of MKN-45-FAK-/- and MKN45 cells and demonstrated that IL-8 was downregulated in FAK-deficient cells. Conversely, we confirmed that IL-8 activates FAK activity. We established that IL-8 promotes the proliferation, colony formation, and migration of gastric cancer cells that are partially mediated by FAK. Thus, we propose that an IL-8-FAK-IL-8 positive feedback loop effects the proliferation and migration of gastric cancer cells.

Cell adhesion tunes inflammatory TPL2 kinase signal transduction

Signaling through adhesion-related molecules is important for cancer growth and metastasis and cancer cells are resistant to anoikis, a form of cell death ensued by cell detachment from the extracellular matrix. Herein, we report that detached carcinoma cells and immortalized fibroblasts display defects in TNF and CD40 ligand (CD40L)-induced MEK-ERK signaling. Cell detachment results in reduced basal levels of the MEK kinase TPL2, compromises TPL2 activation and sensitizes carcinoma cells to death-inducing receptor ligands, mimicking the synthetic lethal interactions between TPL2 inactivation and TNF or CD40L stimulation. Focal Adhesion Kinase (FAK), which is activated in focal adhesions and mediates anchorage-dependent survival signaling, was found to sustain steady state TPL2 protein levels and to be required for TNF-induced TPL2 signal transduction. We show that when FAK levels are reduced, as seen in certain types of malignancy or malignant cell populations, the formation of cIAP2:RIPK1 complexes increases, leading to reduced TPL2 expression levels by a dual mechanism: first, by the reduction in the levels of NF-κΒ1 which is required for TPL2 stability; second, by the engagement of an RelA NF-κΒ pathway that elevates interleukin-6 production, leading to activation of STAT3 and its transcriptional target SKP2 which functions as a TPL2 E3 ubiquitin ligase. These data underscore a new mode of regulation of TNF family signal transduction on the TPL2-MEK-ERK branch by adhesion-related molecules that may have important ramifications for cancer therapy.

Targeted Modulation of FAK/PI3K/PDK1/AKT and FAK/p53 Pathways by Cucurbitacin B for the Antiproliferation Effect Against Human Cholangiocarcinoma Cells

Inadequate responses to traditional chemotherapeutic agents in cholangiocarcinoma (CCA) emphasize a requirement for new effective compounds for the treatment of this malignancy. This study aimed to investigate the antiproliferative property of cucurbitacin B on KKU-100 CCA cells. The determination of underlying molecular mechanisms was also carried out. The results revealed that cucurbitacin B suppressed growth and replicative ability to form colonies of CCA cells, suggesting the antiproliferative effect of this compound against the cells. Flow cytometry analysis demonstrated that the interfering effect of cucurbitacin B on the CCA cell cycle at the G2/M phase was accountable for its antiproliferation property. Accompanied with cell cycle disruption, cucurbitacin B altered the expression of proteins involved in the G2/M phase transition including downregulation of cyclin A, cyclin D1, and cdc25A, and upregulation of p21. Additional molecular studies demonstrated that cucurbitacin B suppressed the activation of focal adhesion kinase (FAK) which consequently resulted in inhibition of its kinase-dependent and kinase-independent downstream targets contributing to the regulation of cell proliferation including PI3K/PDK1/AKT and p53 proteins. In this study, the transient knockdown of FAK using siRNA was employed to ascertain the role of FAK in CCA cell proliferation. Finally, the effect of cucurbitacin B on upstream receptor tyrosine kinases regulating FAK activation was elucidated. The results showed that the inhibitory effect of cucurbitacin B on FAK activation in CCA cells is mediated via interference of EGFR and HER2 expression. Collectively, cucurbitacin B might be a promising drug for CCA treatment by targeting FAK protein.

Cucurbitacin B induces mitochondrial-mediated apoptosis pathway in cholangiocarcinoma cells via suppressing focal adhesion kinase signaling

Low efficacy and high resistance rate associated with existing chemotherapeutic drugs enforce a requirement for novel therapeutic strategies for extremely aggressive cholangiocarcinoma (CCA). In the present study, the apoptosis-inducing activity of cucurbitacin B, a compound derived from plants of Cucurbitaceae family, against KKU-100 CCA cells and the underlying mechanism mediating its effect were investigated. The results showed that cucurbitacin B significantly decreased CCA cells viability by induction of apoptosis. Increased apoptotic cell death following cucurbitacin B treatment was correlated with caspase-9 and caspase-3 activations, Bax upregulation, increased cytochrome c, apoptosis-inducing factor release, and decreased Bcl-2 and Bcl-XL levels, suggesting activation of the mitochondrial-mediated apoptosis pathway. Further molecular analyses revealed that cucurbitacin B inhibited focal adhesion kinase (FAK), which is an important regulator of the apoptosis process, and its downstream pathway, PI3K/Akt. Knockdown of FAK expression by small interfering RNA appeared to induce CCA cell apoptosis which was accompanied with elevated level of cytochrome c and cleaved caspase-9, and decreased level of Bcl-2, phospho-PI3K, and phospho-Akt. Taken together, cucurbitacin B induces an intrinsic mitochondrial apoptosis pathway in CCA cells partly through suppression of FAK-mediated oncogenic signaling. This compound should be considered as a candidate agent for CCA treatment.

Rhinacanthin-C Extracted from Rhinacanthus nasutus (L.) Inhibits Cholangiocarcinoma Cell Migration and Invasion by Decreasing MMP-2, uPA, FAK and MAPK Pathways

Cholangiocarcinoma is a malignant tumor with high metastatic and mortality rates. We investigated the effects of rhinacanthin-C on cell proliferation, migration, invasion and the expression of proteins regulating cancer cell invasion-regulated proteins in a cholangiocarcinoma (KKU-M156) cell line. Cytotoxicity of rhinacanthin-C was determined by the SRB assay. Using wound-migration, chamber-migration and chamber-invasion assays, we assessed the effects of rhinacanthin-C against KKU-M156 cells. The activities of matrix metalloproteinases 2 and 9 (MMP-2, MMP-9) and urokinase-type plasminogen activator (uPA) were determined using gelatinase and uPA zymography assays. The expression of invasion-regulated proteins was investigated using western-blot analysis. After treatment with rhinacanthin-C, KKU-M156 cells exhibited antiproliferative effects in a dose-dependent manner with greater efficacy than in Vero cells: IC50 values were 1.50 and 2.37 µM, respectively. Rhinacanthin-C significantly inhibited cell migration and invasion of KKU-M156 cells in a dose-dependent manner. Consistent with this observation, treatment with rhinacanthin-C was associated with a decrease in the expression levels of FAK, p-FAK, MMP-2, and a decrease in the levels of p38-, JNK1/2- and ERK1/2-MAPK pathways as well as inhibiting NF-κB/p65 expression and translocation of NF-κB/p65 to the nucleus. We have shown for the first time that the anti-metastatic effects of rhinacanthin-C on KKU-M156 cells are mediated via inhibition of the expression of invasion-regulated proteins. Rhinacanthin-C may deserve consideration as a potential agent for the treatment of cholangiocarcinoma.

Prognostic Value of Focal Adhesion Kinase (FAK) in Human Solid Carcinomas: A Meta-Analysis

Background

Recently, the number of reports on focal adhesion kinase (FAK) as a vital therapeutic target in solid carcinomas has increased; however, the prognostic role of FAK status remains poorly understood. This study aims to evaluate the prognostic effect of FAK by means of a meta-analysis.

Methods

We performed a systematic literature search in order to examine the correlation between expression of FAK and overall survival(OS). The hazard ratio (HR) of OS was used to measure survival. A random-effects model was used to pool study statistics. Sensitivity and publication bias analyses were also conducted.

Results

Thirty eligible studies involving 4702 patients were included. The median expression rate of FAK was 54%. Meta-analysis of the HRs demonstrated that high FAK expression was associated with worse OS (average HR = 2.073, 95%confidence interval[CI]:1.712–2.510, p = 0.000). Regarding cancer type, FAK was associated with worse OS in gastric cancer (HR = 2.646,95% CI:1.743–4.017, p = 0.000), hepatocellular carcinoma (HR = 1.788,95% CI:1.228–2.602, p = 0.002), ovarian cancer (HR = 1.815, 95% CI: 1.193–2.762, p = 0.005), endometrial cancer (HR = 4.149, 95% CI:2.832–6.079, p = 0.000), gliomas (HR = 2.650, 95% CI: 1.205–5.829, p = 0.015), and squamous cell carcinoma (HR = 1,696, 95% CI: 1.030–2.793, p = 0.038). No association was found between HR and disease staging according to our meta-regression analysis.

Conclusions

Our study shows that high expression of FAK is associated with a worse OS in patients with carcinomas, but the association between FAK and prognosis varies according to cancer type. The value of FAK status in clinical prognosis in cancer needs further research.

Focal adhesion kinase: predictor of tumour response and risk factor for recurrence after neoadjuvant chemoradiation in rectal cancer

Rectal cancer represents about 30% of colorectal cancers, being around 50% locally advanced at presentation. Chemoradiation (CRT) followed by total mesorectal excision is the standard of care for these locally advanced stages. However, it is not free of adverse effects and toxicity and the complete pathologic response rate is between 10% and 30%. This makes it extremely important to define factors that can predict response to this therapy. Focal adhesion kinase (FAK) expression has been correlated with worse prognosis in several tumours and its possible involvement in cancer radio- and chemosensitivity has been suggested; however, its role in rectal cancer has not been analysed yet. To analyse the association of FAK expression with tumour response to CRT in locally advanced rectal cancer. This study includes 73 patients with locally advanced rectal cancer receiving standard neoadjuvant CRT followed by total mesorectal excision. Focal adhesion kinase protein levels were immunohistochemically analysed in the pre-treatment biopsies of these patients and correlated with tumour response to CRT and patients survival. Low FAK expression was significantly correlated with local and distant recurrence (P = 0.013). Low FAK expression was found to be a predictive marker of tumour response to neoadjuvant therapy (P = 0.007) and patients whose tumours did not express FAK showed a strong association with lower disease-free survival (P = 0.01). Focal adhesion kinase expression predicts neoadjuvant CRT response in rectal cancer patients and it is a clinically relevant risk factor for local and distant recurrence.

Focal adhesion protein expression in human diffuse large B-cell lymphoma

AIMS

Focal adhesions have been associated with poor prognosis in multiple cancer types, but their prognostic value in diffuse large B-cell lymphoma (DLBCL) has not been evaluated. The aim of this study was to investigate the expression patterns and the prognostic value of the focal adhesion proteins FAK, Pyk2, p130Cas and HEF1 in DLBCL.

METHODS AND RESULTS

Focal adhesion protein expression was examined using immunohistochemistry in normal lymphoid tissues and in 60 DLBCL patient samples. Kaplan-Meier survival and Cox regression analysis were performed to evaluate the correlation of focal adhesion protein expression with patient prognosis. FAK, Pyk2, p130Cas and HEF1 expression was mostly found in the germinal centres of normal human lymphoid tissues. When assessed in DLBCL samples, FAK, Pyk2, p130Cas and HEF1 were highly expressed in 45%, 34%, 42% and 45% of the samples, respectively. Multivariate Cox analysis revealed that decreased FAK expression was a significant independent predictor of poorer disease outcome.

CONCLUSIONS

FAK expression is an independent prognostic factor in DLBCL. Our results suggest that the addition of FAK immunostaining to the current immunohistochemical algorithms may facilitate risk stratification of DLBCL patients.

FAK acts as a suppressor of RTK-MAP kinase signalling in Drosophila melanogaster epithelia and human cancer cells

Receptor Tyrosine Kinases (RTKs) and Focal Adhesion Kinase (FAK) regulate multiple signalling pathways, including mitogen-activated protein (MAP) kinase pathway. FAK interacts with several RTKs but little is known about how FAK regulates their downstream signalling. Here we investigated how FAK regulates signalling resulting from the overexpression of the RTKs RET and EGFR. FAK suppressed RTKs signalling in Drosophila melanogaster epithelia by impairing MAPK pathway. This regulation was also observed in MDA-MB-231 human breast cancer cells, suggesting it is a conserved phenomenon in humans. Mechanistically, FAK reduced receptor recycling into the plasma membrane, which resulted in lower MAPK activation. Conversely, increasing the membrane pool of the receptor increased MAPK pathway signalling. FAK is widely considered as a therapeutic target in cancer biology; however, it also has tumour suppressor properties in some contexts. Therefore, the FAK-mediated negative regulation of RTK/MAPK signalling described here may have potential implications in the designing of therapy strategies for RTK-driven tumours.

Caveolin 1 expression correlates with poor prognosis and focal adhesion kinase expression in gastric cancer

OBJECTIVE

Caveolin 1 gene is known as a tumor promoter or suppressor, depending on the tumor type and/or tumor stage. We aimed to investigate the clinical significance of caveolin 1 protein (Cav1) expression in gastric cancer (GC).

METHODS

Immunohistochemistry was performed on tissue array slides containing 405 GC specimens. The relationships between Cav1 expression and clinicopathological factors, prognosis, focal adhesion kinase expression, mucin phenotypes and p53 expression were analyzed.

RESULTS

In non-neoplastic gastric mucosa, Cav1 was not expressed in the epithelial compartment. In GC, positive staining of Cav1 was shown in 22 (5.4%) of 405 cases and was significantly higher in the advanced GC group than in the early GC group (p = 0.037). Also, it was significantly associated with advanced pTNM stage (p = 0.027) and lymph node metastasis (p = 0.018). Moreover, survival analysis showed that Cav1 expression was an independent prognostic factor of poor survival (p = 0.028). In addition, the expression of Cav1 was positively correlated with that of focal adhesion kinase (p = 0.034).

CONCLUSIONS

These results indicate that the expression of Cav1 is significantly correlated with cancer progression and poor prognosis in GC. Thus, Cav1 could supplement its protein expression for the diagnosis and treatment of GC.

Ras-induced and extracellular signal-regulated kinase 1 and 2 phosphorylation-dependent isomerization of protein tyrosine phosphatase (PTP)-PEST by PIN1 promotes FAK dephosphorylation by PTP-PEST

Protein tyrosine phosphatase (PTP)-PEST is a critical regulator of cell adhesion and migration. However, the mechanism by which PTP-PEST is regulated in response to oncogenic signaling to dephosphorylate its substrates remains unclear. Here, we demonstrate that activated Ras induces extracellular signal-regulated kinase 1 and 2-dependent phosphorylation of PTP-PEST at S571, which recruits PIN1 to bind to PTP-PEST. Isomerization of the phosphorylated PTP-PEST by PIN1 increases the interaction between PTP-PEST and FAK, which leads to the dephosphorylation of FAK Y397 and the promotion of migration, invasion, and metastasis of v-H-Ras-transformed cells. These findings uncover an important mechanism for the regulation of PTP-PEST in activated Ras-induced tumor progression.

Evaluation of FAK and Src expression in human benign and malignant thyroid lesions

Focal Adhesion Kinase (FAK) and Src have been reported to regulate tumor growth, invasion, metastasis and angiogenesis. The present study aimed to evaluate by immunohistochemistry the clinical significance of FAK and Src expression in 108 patients with benign and malignant thyroid lesions. Total FAK expression provided a distinct discrimination between malignant and benign (p = 0.00001), as well as between papillary carcinoma and hyperplastic nodules thyroid lesions (p = 0.00005), being also associated with follicular cells' proliferative capacity (p = 0.0003). In malignant thyroid lesions, total FAK expression was associated with tumor size (p = 0.0455), and presence of capsular (p = 0.0102) and lymphatic (p = 0.0173) invasion. Total Src expression was borderline increased in cases of papillary carcinoma compared to hyperplastic nodules (p = 0.0993), being also correlated with tumor size (p = 0.0169). FAK and Src expression was ascribed to a significant extent to the phosphorylated forms of the enzymes, which provided a better discrimination between malignant and benign thyroid lesions. The current data revealed that FAK and to a lesser extent Src expression could be considered of clinical utility in thyroid neoplasia with potential use as therapeutic targets.

Focal adhesion kinase (FAK) gene amplification and its clinical implications in gastric cancer

Focal adhesion kinase, a nonreceptor tyrosine kinase, is known to be associated with tumor progression in various tumors. Because the clinical implications of focal adhesion kinase overexpression in gastric cancer have been inconsistent, we extended previous studies and evaluated focal adhesion kinase gene amplification as well as its protein expression. Immunohistochemical tissue array analysis showed that focal adhesion kinase immunoreactivity was present in both the cytoplasm and membrane of gastric cancer cells. Diffuse immunoreactivity of focal adhesion kinase protein in cytoplasm or membrane was found in 240 (54%) or 263 (59%) of 444 surgical samples, respectively, and positively correlated with tumor size, depth of tumor infiltration, nodal metastasis, distant metastasis, lymphatic invasion, and venous invasion (P < .001). Regarding focal adhesion kinase gene amplification, fluorescence in situ hybridization analysis showed focal adhesion kinase gene amplification in 34 (8.9%) of 384 gastric cancer specimens, whereas there was no amplification in any case of atrophy, intestinal metaplasia, or adenoma/dysplasia. Focal adhesion kinase gene amplification was positively associated with age (P = .012), tumor size (P = .007), nodal metastasis (P = .021), distant metastasis (P = .029), lymphatic invasion (P = .006), venous invasion (P = .032), and perineural invasion (P = .023). Focal adhesion kinase protein expression and gene amplification were positively correlated with each other, and each of them was found to be an independent poor prognostic factor (P < .01). In conclusion, our results showed that either focal adhesion kinase protein expression or focal adhesion kinase gene amplification was significantly correlated with cancer progression and poor prognosis in gastric cancer. Thus, focal adhesion kinase gene amplification could supplement its protein expression for the diagnosis and treatment of gastric cancer.

Decreased expression of focal adhesion kinase is associated with a poor prognosis in extrahepatic bile duct carcinoma

Extrahepatic bile duct (EBD) carcinoma is a relatively rare neoplasm worldwide, and its prognostic outcome remains unfavorable. Therefore, it is necessary to investigate molecular biologic features of EBD carcinomas. Focal adhesion kinase (FAK) plays a pivotal role in cell adhesion, survival, migration, and signal transduction, but FAK expression in EBD carcinomas has not been evaluated. We measured FAK expression in 76 EBD carcinomas using immunohistochemistry and evaluated its correlation with tumor progression, clinicopathologic factors, and patient outcome. FAK was expressed specifically in the cytoplasm of all normal biliary epithelia (100%). Most dysplastic epithelia also showed positive FAK expression except for 2 cases (92%), whereas EBD carcinomas showed positive FAK expression in 53 (77%) of 76 cases (P < .001, versus normal epithelia). FAK expression tended to be gradually reduced along as dysplasia progressed to carcinoma. Although FAK expression had no association with clinicopathologic factors, the positive FAK expression group showed significantly better survival than the negative FAK expression group (P < .05). However, FAK expression was not an independent prognostic factor by multivariate analysis. In conclusion, FAK expression was significantly lower in EBD carcinomas than in normal biliary epithelia and decreased expression of FAK seemed to be indicative of a poor prognosis, suggesting that FAK might play an inhibitory role for tumor progression in EBD carcinomas. It is important to notice the role of FAK in tumor progression when treatments targeting FAK are performed.

FAK phosphorylation by ERK primes ras-induced tyrosine dephosphorylation of FAK mediated by PIN1 and PTP-PEST

Activated Ras has been found in many types of cancer. However, the mechanism underlying Ras-promoted tumor metastasis remains unclear. We demonstrate here that activated Ras induces tyrosine dephosphorylation and inhibition of FAK mediated by the Ras downstream Fgd1-Cdc42-PAK1-MEK-ERK signaling cascade. ERK phosphorylates FAK S910 and recruits PIN1 and PTP-PEST, which colocalize with FAK at the lamellipodia of migrating cells. PIN1 binding and prolyl isomerization of FAK cause PTP-PEST to interact with and dephosphorylate FAK Y397. Inhibition of FAK mediated by this signal relay promotes Ras-induced cell migration, invasion, and metastasis. These findings uncover the importance of sequential modification of FAK-by serine phosphorylation, isomerization, and tyrosine dephosphorylation--in the regulation of FAK activity and, thereby, in Ras-related tumor metastasis.

Expression and clinical significance of focal adhesion kinase in the two distinct histological types, intestinal and diffuse, of human gastric adenocarcinoma

Focal adhesion kinase (FAK), a non-receptor tyrosine kinase protein, acts as an early modulator of integrin signaling cascade, regulating basic cellular functions. In transformed cells, unopposed FAK signaling has been considered to promote tumor growth, progression and metastasis. The aim of this study was to assess the clinical significance of FAK expression in the two distinct histological types of human gastric neoplasia. FAK expression was assessed immunohistochemically in tumoral samples of 66 gastric adenocarcinoma cases, 30 intestinal and 36 diffuse type, and was statistically analyzed in relation to various clinicopathological characteristics, tumor proliferative capacity and patients' survival. In intestinal type carcinomas, enhanced FAK expression was significantly associated with increased tumor proliferative capacity (P = 0.012). In diffuse type carcinomas, FAK staining intensity was significantly correlated with tumor size (P = 0.026) and disease stage (P = 0.024), presenting also a borderline association with nodal status (P = 0.053). In diffuse type carcinomas, enhanced FAK expression was significantly associated with longer overall survival times (log-rank test, P = 0.014), being also identified as an independent prognostic factor in multivariate analysis (Cox regression, P = 0.016). In contrast, patients with intestinal type tumors and enhanced FAK expression were characterized by shorter overall survival times, without though reaching statistical significance (log-rank test, P = 0.092). The current data support evidence that FAK protein may be considered as a diagnostic and prognostic marker in gastric neoplasia. Further studies conducted on larger clinical samples and highlighting on the distinct impact of the two histological types are warranted to delineate the clinical significance of FAK protein in gastric neoplasia.

Resistance of tumor cells to cytolytic T lymphocytes involves Rho-GTPases and focal adhesion kinase activation

Tumor cells evade adaptive immunity by a variety of mechanisms, including selection of variants that are resistant to specific cytotoxic T lymphocyte (CTL) pressure. Recently, we have reported that the reorganization of the actin cytoskeleton can be used by tumor cells as a strategy to promote their resistance to CTL-mediated lysis. In this study, we further examined the functional features of a CTL-resistant tumor variant and investigated the relationship between cytoskeleton alteration, the acquisition of tumor resistance to CTL-induced cell death, Rho-GTPases, and focal adhesion kinase (FAK) pathways. Our data indicate that although the resistant cells do not display an increased migratory potential, an alteration of adhesion to the extracellular matrix was observed. When Rho-GTPases were activated in cells by the bacterial CNF1 (cytotoxic necrotizing factor 1), striking changes in the cell morphology, including actin cytoskeleton, focal adhesions, and membrane extensions, were observed. More importantly, such activation also resulted in a significant attenuation of resistance to CTL-induced cell death. Furthermore, we demonstrate that FAK signaling pathways were constitutively defective in the resistant cells. Silencing of FAK in the sensitive target cells resulted in the inhibition of immune synapse formation with specific CTLs and their subsequent lysis. Expression of the FAK mutant (Y397F) resulted in an inhibition of IGR-Heu cell adhesion and of their susceptibility to specific lysis. These results suggest that FAK activation plays a role in the control of tumor cell susceptibility to CTL-mediated lysis.