Epidermal growth factor receptor inhibitors enhance susceptibility to Fas-mediated apoptosis in oral squamous cell carcinoma cells

Overexpression of FADD and Bcl-XS proteins as novel prognostic biomarkers for surgically resected non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) is one of the most widespread cancer with increasing morbidity and mortality. FAS-associated protein with death domain (FADD) is considered as an essential instrument in cell death, whereas Bcl-XS promotes apoptosis through inhibiting the activity of Bcl-2 and Bcl-XL.

OBJECTIVE AND METHODS

We detected the expression of FADD and Bcl-XS in resected NSCLC tissues by immunohistochemistry, and investigated their association with clinicopathological characteristics and prognostic significance of NSCLC patients.

RESULTS

Bcl-XS expression was significantly increased in well and moderate differentiated lung SCC (P= 0.004). Lung ADC patients with overexpression of FADD and lung SCC patients with low expression of Bcl-XS had importantly lower overall survival rates by Kaplan-Meier analysis (P= 0.033, P= 0.02, respectively). Multivariate analysis confirmed that elevated expression of FADD was an independent poor prognostic factor for patients with surgically resected lung ADC (P= 0.027) and increased expression of Bcl-XS was an independent good prognostic factor for patients with surgically resected lung SCC (P= 0.016)CONCLUSION: Elevated expression of FADD was identified as independent poor prognostic factor for patients with surgically resected lung ADC, however, increased expression of Bcl-XS was an independent good prognostic biomarker for patients with surgically resected lung SCC.

In silico analysis of the prognostic value of FAS mRNA in malignancies

Background: FAS is a classical death receptor involved in the FAS/FAS ligand (FASL) apoptosis pathway and plays a role in anti-tumor activity. Some studies have recently reported that FAS can serve as an oncogene that promotes tumor proliferation and maintains the stemness of tumor cells. Hence, its prognostic value in malignancies remains controversial.

Methods: we assessed the prognostic value of FAS mRNA in several types of tumors by online platforms including Kaplan-Meier Plotter and SurvExpress.

Results: FAS mRNA was associated with better overall survival (OS) in breast cancer (Hazard ratio (HR): 0.59 [0.47, 0.73]; p=1.5e-06), gastric cancer (HR: 0.65 [0.54, 0.77]; p=8e-07) and non-small-cell lung cancer (NSCLC) (HR: 0.78 [0.69, 0.89]; p=0.00016), especially in lung adenocarcinoma (HR: 0.64 [0.51, 0.81], p=1.7e-04), female lung cancer (HR:0.72 [0.57, 0.9], p=0.0049) and patients who have never smoked (HR: 0.39 [0.21, 0.7], p=0.0012). However, a high level of FAS mRNA expression indicated poorer OS in pancreatic cancer (HR: 1.33 [1.06, 1.66]; p=0.01) and acute myeloid leukemia (AML) (HR: 1.57 [1.02, 2.41], p=0.04). Additionally, FAS showed no prognostic value in renal carcinoma, head and neck carcinoma, hepatic cancer, ovarian cancer, colorectal cancer or glioblastoma. The results from the Cell Miner tool revealed that FAS expression was associated with the sensitivity of tumor cells to cabozantinib and erlotinib.

Conclusions: In summary, the dominant function of FAS may vary in different malignancies. FAS mRNA expression was correlated with better OS in breast cancer, gastric cancer and lung cancer, but worse OS in pancreatic cancer and AML. We also suggested that FAS mRNA expression could be a potential biomarker for cabozantinib and erlotinib.

Combined oridonin with cetuximab treatment shows synergistic anticancer effects on laryngeal squamous cell carcinoma: involvement of inhibition of EGFR and activation of reactive oxygen species-mediated JNK pathway

Epidermal growth factor receptor (EGFR), a transmembrane glycoprotein, is expressed at high levels in a large proportion of laryngeal squamous cell carcinoma (LSCC). Cetuximab (Cet), an anti-EGFR monoclonal antibody, has limited clinical outcome for patients with head and neck squamous cell carcinoma. Our previous studies showed that oridonin (ORI), a natural and safe kaurene diterpenoid isolated from Rabdosia rubescens, inhibited cell growth in HEp-2 cells through inhibition of EGFR phosphorylation. The aim of the present study was to determine whether ORI could improve the anticancer efficacy of Cet on LSCC. We observed that the combination with Cet and ORI synergistically inhibited cell growth associated with Fas-mediated apoptosis and G2/M phase arrest in two LSCC cell lines (HEp-2 and Tu212 cells). Moreover, combination treatment caused cell death associated with suppression of p-EGFR and activation of reactive oxygen species (ROS)-mediated JNK pathway. In nude mice bearing HEp-2 xenografts, ORI plus Cet caused a significant tumor regression through induction of apoptosis and inhibition of proliferation with no side-effect. Together, our findings suggest that the combination of ORI and Cet has the potential to enhance tumor responses and may significantly improve therapeutic outcomes in LSCC.

Targeting the Anti-Apoptotic Protein c-FLIP for Cancer Therapy

Cellular FLICE (FADD-like IL-1beta-converting enzyme)-inhibitory protein (c-FLIP) is a major resistance factor and critical anti-apoptotic regulator that inhibits tumor necrosis factor-alpha (TNF-alpha), Fas-L, and TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis as well as chemotherapy-triggered apoptosis in malignant cells. c-FLIP is expressed as long (c-FLIP(L)), short (c-FLIP(S)), and c-FLIP(R) splice variants in human cells. c-FLIP binds to FADD and/or caspase-8 or -10 in a ligand-dependent and-independent fashion, which in turn prevents death-inducing signaling complex (DISC) formation and subsequent activation of the caspase cascade. Moreover, c-FLIP(L) and c-FLIP(S) are known to have multifunctional roles in various signaling pathways, as well as activating and/or upregulating several cytoprotective signaling molecules. Upregulation of c-FLIP has been found in various tumor types, and its downregulation has been shown to restore apoptosis triggered by cytokines and various chemotherapeutic agents. Hence, c-FLIP is an important target for cancer therapy. For example, small interfering RNAs (siRNAs) that specifically knockdown the expression of c-FLIP(L) in diverse human cancer cell lines augmented TRAIL-induced DISC recruitment and increased the efficacy of chemotherapeutic agents, thereby enhancing effector caspase stimulation and apoptosis. Moreover, small molecules causing degradation of c-FLIP as well as decreasing mRNA and protein levels of c-FLIP(L) and c-FLIP(S) splice variants have been found, and efforts are underway to develop other c-FLIP-targeted cancer therapies. This review focuses on (1) the functional role of c-FLIP splice variants in preventing apoptosis and inducing cytokine and drug resistance; (2) the molecular mechanisms that regulate c-FLIP expression; and (3) strategies to inhibit c-FLIP expression and function.

Role of molecular markers in the management of head and neck cancers

PURPOSE OF REVIEW

Head and neck squamous cell carcinoma (HNSCC) is the fifth most common cancer worldwide. Despite advances in treatment, the prognosis remains poor. HNSCC comprise a wide spectrum of neoplasms with different tumor biologies, prognosis and response to therapies. Current tumor classification is based on morphology and anatomic distribution, which leads to a homogeneous treatment for different diseases. Moreover, traditional diagnostic methods such as clinical assessment, histopathological examination, and imaging techniques are limited in their capacity to provide information on prognosis and decision making.

RECENT FINDINGS

Molecular markers have increased the understanding of the pathogenesis of head and neck cancer because they give increasing insight into tumor biology, prognosis, and response to therapy. The practical application of these discoveries is beginning to assist greatly in the evaluation and treatment of HNSCC to achieve a more personalized and effective approach.

SUMMARY

This article focuses on the molecular markers that have already been extensively studied such as epidermal growth factor receptor and human papillomavirus as well as those that offer potential for personalized therapy such as HIF-1 and ERCC-1. The ideal biomarker should be assayed accurately and easily, highly specific, and cost effective. Thus, a validation is required before their implementation into clinical guidelines.

Caspase-8 as a therapeutic target in cancer

Caspase-8 is an apical caspase which initiates programmed cell death following death receptor ligation. This central role in apoptosis has prompted significant clinical interest in regulating caspase-8 expression and proteolytic activity. However, caspase-8 has also been found to play a number of non-apoptotic roles in cells, such as promoting activation NF-κB signaling, regulating autophagy and altering endosomal trafficking, and enhancing cellular adhesion and migration. Therefore, depending upon the specific cellular context, caspase-8 may either potentiate or suppress tumor malignancy. Accordingly, a marked heterogeneity exists in the expression patterns of caspase-8 among different tumor types. Therapeutics have been developed which can increase caspase-8 expression, yet it remains unclear whether this approach will be beneficial in all cases. Care is warranted, and the role of caspase-8 should be addressed on a case by case basis.

Emerging drugs to treat squamous cell carcinomas of the head and neck

IMPORTANCE OF THE FIELD

Head and neck squamous cell carcinoma (HNSCC) is the eighth leading cause of cancer death worldwide. Despite advances in surgery and chemoradiation therapy, there has been little improvement in survival rates over the past 4 decades. Additionally, surgery and chemoradiotherapy have serious side effects. The development of agents with greater efficacy and tolerability is needed.

AREAS COVERED IN THIS REVIEW

EGFR is the only proven molecular target for HNSCC therapy. Cetuximab, the sole FDA-approved molecular targeted HNSCC therapy, and other potential targeted therapies are being evaluated in preclinical, clinical and post-marketing studies. Here, we review the emerging targets for biological agents in HNSCC and the rationale for their selection.

WHAT THE READER WILL GAIN

Key information in the development of new drug targets and the emergence of new biomarkers are discussed. Readers will gain insight regarding the limitations of current therapies, the impact of recently approved targeted therapies and the influence that predictive biomarkers will have on drug development.

TAKE HOME MESSAGE

The head and neck cancer drug market is rapidly evolving. Coordination between drug and biomarker development efforts may soon yield targeted therapies that can achieve the promise of personalized cancer medicine.

Molecular targeted therapies in head and neck cancer--an update of recent developments-

Targeted therapies have made their way into clinical practice during the past decade. They have caused a major impact on the survival of cancer patients in many areas of clinical oncology and hematology. Indeed, in some hematologic malignancies, such as chronic myelogenous leukemia or non-Hodgkin's lymphomas, biologicals and antibodies specifically designed to target tumour-specific proteins have revolutionized treatment standards. In solid tumours, new drugs targeting EGF- or VEGF- receptors are now approved and are entering clinical practise for treatment of colon, lung, kidney and other cancers, either alone or in combination with conventional treatment approaches. Recent data have now shown that molecular targeted therapy might display efficacy in patients with head and neck squamous cell carcinoma (HNSCC) as well. The evaluated biologicals are generally well tolerated from HNSCC patients, who usually have the burden of multiple co-morbidities that interfere with conventional systemic treatment options. Therefore, molecular targeted therapies offer new treatment options even for heavily pretreated and seriously ill patients usually unable to tolerate chemotherapy or radiation therapy. The two most promising and advanced strategies are the blockage of growth-factor based cellular signalling and interference with angiogenesis-related pathways. But inhibitors of alternative targets, such as Scr and proteasomes, have already been evaluated in early clinical trials with HNSCC patients.

Inhibition of EGFR signaling augments oridonin-induced apoptosis in human laryngeal cancer cells via enhancing oxidative stress coincident with activation of both the intrinsic and extrinsic apoptotic pathways

Oridonin, a bioactive diterpenoid isolated from Rabdosia rubescens, has been reported to have anti-tumor effects, while the epidermal growth factor receptor (EGFR) signal pathway has been reported to play a vital role in the biological progression of several tumors and to be a target for therapeutic intervention. In this work, we show that inhibition of EGFR with tyrphostin AG1478 enhances oridonin-induced cell death in human laryngeal cancer cells HEp-2, a cell line characterized by EGFR gene amplification. The enhanced apoptotic effect correlates with high expression and activation of Bax, FADD, caspase-8 as well as caspase-3 and decreased protein levels of Bcl(2) and SIRT1, suggesting that both the extrinsic and intrinsic apoptosis pathways are involved in the apoptotic processes. However, treatment with oridonin and AG1478 greatly enhances nuclear translocation of apoptosis inducing factor (AIF) without caspase-9 activation, indicating that the apoptosis occurs via a caspase-9-independent mitochondrial pathway. Here, it is the active form of caspase-8 but not caspase-9 that activates downstream effector caspase-3, resulting in the cleavage of critical cellular proteins and apoptosis. Furthermore, the combined use of AG1478 and oridonin augments the production of reactive oxygen species (ROS). Incubation of cells with N-Acetylcysteine (NAC) attenuates the apoptosis and the mitochondrial membrane potential (Deltapsim) disruption induced by the combination of oridonin and AG1478, which indicates that ROS plays a pivotal role in cell death. In conclusion, targeting EGFR combined with other conventional pro-apoptotic drugs should be a potentially very effective anti-neoplastic therapy for laryngeal cancer.

Epidermal growth factor receptor as a target for anti-proliferative treatment of proliferative cholangitis in hepatolithiasis

BACKGROUND

In recent years, with a deeper understanding of pathologic changes in hepatolithiasis, more and more attention has been paid to the relationship of postoperative remnant proliferative cholangitis (PC) with stone recurrence and biliary restenosis, but effective management strategies have not yet been developed. Thus, the aim of this study was to determine whether epidermal growth factor receptor inhibitor (AG-1478) could inhibit hyperplasia and lithogenic potentiality of PC.

METHODS

The PC animal model was established via retrograde insertion of a 5-0 nylon thread into the common bile duct through Vater's papilla. The common bile duct in the therapeutic group received a single intraluminal administration of AG-1478, followed by weekly intraperitoneal injections of AG-1478. Subsequently, influence of EGFR inhibitor on hyperplasia, apoptosis, and lithogenic potential of PC were evaluated via histology, expression changes of EGFR, BrdU, Ki-67, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), Fas, mucin 5 AC, and collagen I.

RESULTS

EGFR inhibitor AG-1478 was effective not only in inhibiting the mRNA and protein expression of EGFR, BrdU, and Ki-67, but also in increasing Fas mRNA expression and TUNEL-positive cells, as a result leading to the inhibition of hyperplasia of the biliary epithelium, submucosal gland, and collagen fibers in the diseased bile duct. Additionally, collagen I expression and fibrous thickness of the bile duct wall was significantly reduced, thereby reducing the incidence of biliary tract stricture secondary to PC. Also of note, treatment with AG-1478 could efficiently decrease the lithogenic potential of PC via inhibition of mucin 5AC expression and mucoglycoprotein secretion, hereby facilitating prevention of stone recurrence.

CONCLUSION

EGFR antagonist AG-1478 had a potent anti-proliferative and anti-fibrotic effectiveness on PC and, therefore, holds promise as a candidate of PC treatment.

Targeting EGFR with photodynamic therapy in combination with Erbitux enhances in vivo bladder tumor response

BACKGROUND

Photodynamic therapy (PDT) is a promising cancer treatment modality that involves the interaction of the photosensitizer, molecular oxygen and light of specific wavelength to destroy tumor cells. Treatment induced hypoxia is one of the main side effects of PDT and efforts are underway to optimize PDT protocols for improved efficacy. The aim of this study was to investigate the anti-tumor effects of PDT plus Erbitux, an angiogenesis inhibitor that targets epidermal growth factor receptor (EGFR), on human bladder cancer model. Tumor-bearing nude mice were assigned to four groups that included control, PDT, Erbitux and PDT plus Erbitux and tumor volume was charted over 90-day period.

RESULTS

Our results demonstrate that combination of Erbitux with PDT strongly inhibits tumor growth in the bladder tumor xenograft model when compared to the other groups. Downregulation of EGFR was detected using immunohistochemistry, immunofluorescence and western blotting. Increased apoptosis was associated with tumor inhibition in the combination therapy group. In addition, we identified the dephosphorylation of ErbB4 at tyrosine 1284 site to play a major role in tumor inhibition. Also, at the RNA level downregulation of EGFR target genes cyclin D1 and c-myc was observed in tumors treated with PDT plus Erbitux.

CONCLUSION

The combination therapy of PDT and Erbitux effectively inhibits tumor growth and is a promising therapeutic approach in the treatment of bladder tumors.