Role of β-catenin in cisplatin resistance,relapse and prognosis of head and neck squamous cell carcinoma

Background

Head and neck squamous cell carcinoma (HNSCC) is one of the most common types of cancer in India with high incidence and rapid recurrence rates. Here, we aimed to investigate the role of β-catenin, a developmental pathway gene, in HNSCC therapy resistance, DNA damage response, recurrence and prognosis.

Methods

In total 80 HNSCC samples were included. Western blot, immunohistochemistry and qRT-PCR analyses were performed to assess β-catenin expression in the cut margin and tumor areas of each sample. Kaplan-Meier analyses were performed to correlate β-catenin expression with the survival and prognosis of HNSCC patients. In addition, chemo-resistance, DNA damage response and DNA repair capacities were evaluated in HNSCC-derived cell lines through LiCl-mediated up-regulation and siRNA-mediated silencing of β-catenin expression.

Results

We observed β-catenin up-regulation in cut margin areas of recurrent patients compared to their corresponding tumor regions, which subsequently could be associated with poor prognosis. In addition, we found that LiCl-mediated up-regulation of β-catenin in HNSCC-derived cells led to cisplatin resistance, evasion of apoptosis, enhanced DNA repair and enhanced migration. The effects of β-catenin silencing correlated with its putative role in chemo-resistance and DNA damage response.

Conclusion

From our results we conclude that β-catenin may contribute to HNSCC therapy resistance and disease relapse. As such, β-catenin may be explored as a therapeutic target along with conventional therapeutics.

     

IKK phosphorylation of NF-κB at serine 536 contributes to acquired cisplatin resistance in head and neck squamous cell cancer

Current treatment methods for advanced head and neck squamous cell carcinoma (HNSCC) include surgery, radiation therapy and chemotherapy. For recurrent and metastatic HNSCC, cisplatin is the most common treatment option, but most of patients will eventually develop cisplatin resistance. Therefore, it is imperative to define the mechanisms involved in cisplatin resistance and find novel therapeutic strategies to overcome this deadly disease. In order to determine the role of nuclear factor-kappa B (NF-κB) in contributing to acquired cisplatin resistance in HNSCC, the expression and activity of NF-κB and its upstream kinases, IKKα and IKKβ, were evaluated and compared in three pairs of cisplatin sensitive and resistant HNSCC cell lines, including a pair of patient derived HNSCC cell line. The experiments revealed that NF-κB p65 activity was elevated in cisplatin resistant HNSCC cells compared to that in their parent cells. Importantly, the phosphorylation of NF-κB p65 at serine 536 and the phosphorylation of IKKα and IKKβ at their activation loops were dramatically elevated in the resistant cell lines. Furthermore, knockdown of NF-κB or overexpression of p65-S536 alanine (p65-S536A) mutant sensitizes resistant cells to cisplatin. Additionally, the novel IKKβ inhibitor CmpdA has been shown to consistently block the phosphorylation of NF-κB at serine 536 while also dramatically improving the efficacy of cisplatin in inhibition of cell proliferation and induction of apoptosis in the cisplatin resistant cancer cells. These results indicated that IKK/NF-κB plays a pivotal role in controlling acquired cisplatin resistance and that targeting the IKK/NF-κB signaling pathway may provide a possible therapeutic method to overcome the acquired resistance to cisplatin in HNSCC.     

Association of α1 acidic glycoprotein and squamous cell carcinoma of the head and neck

Serum from patients with different malignancies contain an abnormal concentration of a a1-acidic-glycoprotein (AAG) and also, increased levels of AAG are associated with the presence of tumor mass. In the present report, serum levels of AAG were measured by radial immunodiffusion in squamous cell carcinoma of the head and neck (SCCHN) patients taking into account disease status parameters such as tumor localization, stage and extension of disease. Immunohistochemical methods, SDS-PAGE and Western-blotting were employed to study the expression of AAG and a carbohydrate related antigen (sialyl Lewis x) in tumor tissues and derived fractions. AAG showed abnormal levels in 7/15 oral cavity tumor patients sera, 2/5 oropharynx and 5/10 larynx tumors; increased AAG serum levels belonged to patients with disseminated disease. On the other hand, the presence of AAG and sialyl Lewis x were demonstrated in carcinoma cells and in derived fractions from tumor tissues belonging to patients with elevated AAG serum levels. In the present study, we have found elevated levels of AAG in serum samples from SCCHN patients; these neoplastic cells are capable to express AAG.     

Mutant epidermal growth factor receptor contributes to head and neck cancer growth and resistance to EGFR targeting

Epidermal growth factor receptor (EGFR) is overexpressed in head and neck squamous-cell carcinoma (HNSCC) and its expression levels correlate with decreased patient survival. Nonetheless, therapies aiming at blocking EGFR has shown limited efficacy in a proportion of patients with HNSCC in clinical trials. Sok et al. in a recent paper (Clin Cancer Res, 2006, 12:5064-5073 ) attempted to ascertain whether it is due to mutation of EGFR. As the most common form of mutation of EGFR seen in several other types of cancer is a truncation mutation, EGFR     

NF-κB participates in chemokine receptor 7-mediated cell survival in metastatic squamous cell carcinoma of the head and neck

Metastatic squamous cell carcinoma of the head and neck (SCCHN) has been shown to express chemokine receptor 7 (CCR7), which activates phosphoinositide-3 kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) signal pathway to promote the invasion and survival of SCCHN cells. Since nuclear factor-kappa B (NF-κB) is shown to be the downstream signal molecule of PI3K/Akt in many tumors, we investigated whether it also exists in the CCR7 pathway in SCCHN, and the relationship between NF-κB and PI3K/Akt/mTOR, and the role it plays in SCCHN. We assayed the phosphorylation of the inhibitor of NF-κB (IκBα), the NF-κB DNA-binding capacity and location. The results showed that the interaction between CCR7 and the ligand for CCR7, CCL19, induces phosphorylation of IκBα, causes NF-κB to translocate to the nucleus and raises the DNA-binding capacity of NF-κB. The phosphorylation and DNA-binding capacity were abolished by the inhibition of CCR7, PI3K, Akt and mTOR. Further research demonstrated that inhibitors of NF-κB and CCR7-PI3K attenuate the survival of CCR7-mediated cells, causing decreased viability, increased apoptosis and increased cell cycle arrest in SCCHN cells. In clinical samples from 78 patients, immunohistochemical assay also showed that CCR7 and NF-κB are not only highly expressed in SCCHN, but also correlated with each other, and related to lymph node metastasis and clinical stage. Together, our data indicate that NF-κB is activated by CCR7 via PI3K/Akt/mTOR, and this signal pathway plays an important role in regulating the cell survival and prognosis of SCCHN.     

Synergistic effects of imatinib and carboplatin on VEGF, PDGF and PDGF-Rα/ß expression in squamous cell carcinoma of the head and neck in vitro

Head and neck squamous cell carcinoma (HNSCC) is an aggressive epithelial malignancy. The development of new treatment modalities in order to improve long-term survival of patients with HNSCC is imperative. Numerous studies have demonstrated that carcinogenesis and tumor cell dissemination is influenced by the tumor microenvironment. The protein-kinase-receptors (PTKs) are essential elements of the intracellular signal transduction pathway and regulate cell growth, development and apoptosis. Cell proliferation, migration, induction of tumor vascularization and carcinogenesis, invasion is regulated by a variety of angiogenic factors, such as PDGF (platelet-derived growth factor), VEGF (vascular endothelial growth factor) and their respective tyrosine kinase receptors (PDGF-R and VEGF-R). They present promising targets for anti-cancer therapy through abrogation of impaired signaling pathways. Indeed, imatinib, a small molecule drug targeting these protein kinases, has antiproliferative effects in several cancer types. The purpose of this study was to investigate the potential synergism of imatinib and carboplatin on the expression of PDGF, PDGF-R α/? and VEGF in different HNSCC cell lines. Several tumor cell lines were subjected to increasing concentrations of carboplatin (3 and 7.5 μmol/l) and imatinib (18 and 30 μmol/l) and ELISA, immunohistochemical methods and RQ-PRC after 48, 72, 120 and 240 h were used to assess their expression levels. While PDGF-Rα/? expression was unimpaired at lower imatinib concentrations (18 μmol/l), PDGF-Rα/? expression was suppressed at 30 μmol/l, and suppression was enhanced by the presence of carboplatin. By RQ-PCR, a significant reduction of PDGF-Rα/? expression was detected (p<0.5). We observed explicit significant reduction in VEGF levels with increasing concentrations of imatinib and with the combination of the two chemotherapeutic drugs (p<0.5). We report for the first time evidence of synergism of imatinib and carboplatin in suppressing VEGF, PDGF and PDGF-Rα/? expression in HNSCC.     

Melittin enhances radiosensitivity of hypoxic head and neck squamous cell carcinoma by suppressing HIF-1α

Hypoxia is a widespread phenomenon present in many human solid tumors and is associated with a poor prognosis and therapy resistance. Here, we tested the feasibility of melittin, a major component of bee venom, on radiosensitization of hypoxic head and neck squamous cell carcinoma (HNSCC). CNE-2 and KB cells were treated with melittin and radiation response was determined. Cell viability, cytotoxicity and apoptosis induction were examined by CCK-8 assay, colony formation assay, and flow cytometry. Expression of hypoxia-inducible factor 1-alpha (HIF-1α) and vascular endothelial growth factor (VEGF) proteins were assessed using western blotting. Additionally, we also examined the effect of melittin on tumor growth and radiosensitivity in vivo using a xenograft model of HNSCC. Treatment with melittin resulted in cell growth inhibition, induction of cell apoptosis, and reduction of HIF-1α and VEGF expression, which has been linked to hypoxia cell radioresistance. In addition, intraperitoneal injection of melittin significantly reduced the growth of HNSCC tumors in CNE-2 tumor-bearing mice. These data suggest that melittin enhances radiosensitivity of HNSCC under hypoxia condition, and this is associated with the suppression of HIF-1α expression. Melittin appears to be a potential radiotherapy sensitization agent due to its significant antihypoxia activity.     

ACR appropriateness criteria® adjuvant therapy for resected squamous cell carcinoma of the head and neck

Locoregional recurrence following surgical resection alone for stage III/IV head and neck cancer is common. Adjuvant radiotherapy has been shown to improve post-operative locoregional control when compared to pre-operative radiotherapy for head and neck cancers. Following surgical resection, adverse pathological features determine the need for adjuvant therapy. High-risk pathologic features include extranodal tumor spread and involved surgical margins. Other adverse pathologic features include T 3-4 tumors, perineural invasion, lymphovascular space invasion, low neck adenopathy, and multiple tumor involved cervical lymph nodes. The standard adjuvant therapies are post-operative radiation therapy or post-operative chemoradiotherapy. Post-operative chemoradiotherapy yields superior locoregional control, progression-free survival, and in some studies, overall survival compared to post-operative radiotherapy for high-risk patients in multiple randomized studies. Pooled analyses of randomized data demonstrate that post-operative concurrent chemoradiotherapy is associated with overall survival benefits for patients with involved surgical margins as well as those with extranodal tumor spread. Post-operative radiotherapy concurrent with cisplatin at 100 mg/m(2) every 21 days is the current standard chemoradiotherapy platform adjuvant head and neck cancer treatment. Post-operative radiotherapy and post-operative chemoradiotherapy radiation treatment volumes are not standardized and should be designed based on the risk of recurrence and clinically occult involvement of head and neck subsites and nodal regions. Evidence supports a post-operative radiotherapy and chemoradiotherapy radiation dose of at least 63 Gy for high-risk patients and at least 57 Gy for low risk patients.     

Tumour-suppressive microRNA-29s inhibit cancer cell migration and invasion by targeting laminin–integrin signalling in head and neck squamous cell carcinoma

Background:

Our recent studies of microRNA (miRNA) expression signatures demonstrated that microRNA-29s (miR-29s; miR-29a/b/c) were significantly downregulated in head and neck squamous cell carcinoma (HNSCC) and were putative tumour-suppressive miRNAs in human cancers. Our aim in this study was to investigate the functional significance of miR-29s in cancer cells and to identify novel miR-29s-mediated cancer pathways and responsible genes in HNSCC oncogenesis and metastasis.

Methods:

Gain-of-function studies using mature miR-29s were performed to investigate cell proliferation, migration and invasion in two HNSCC cell lines (SAS and FaDu). To identify miR-29s-mediated molecular pathways and targets, we utilised gene expression analysis and in silico database analysis. Loss-of-function assays were performed to investigate the functional significance of miR-29s target genes.

Results:

Restoration of miR-29s in SAS and FaDu cell lines revealed significant inhibition of cancer cell migration and invasion. Gene expression data and in silico analysis demonstrated that miR-29s modulated the focal adhesion pathway. Moreover, laminin γ2 (LAMC2) and α6 integrin (ITGA6) genes were candidate targets of the regulation of miR-29s. Luciferase reporter assays showed that miR-29s directly regulated LAMC2 and ITGA6. Silencing of LAMC2 and ITGA6 genes significantly inhibited cell migration and invasion in cancer cells.

Conclusion:

Downregulation of miR-29s was a frequent event in HNSCC. The miR-29s acted as tumour suppressors and directly targeted laminin–integrin signalling. Recognition of tumour-suppressive miRNA-mediated cancer pathways provides new insights into the potential mechanisms of HNSCC oncogenesis and metastasis and suggests novel therapeutic strategies for the disease.