Novel therapeutic target for head and neck squamous cell carcinoma: HGF-MET signaling pathway

Imaging c-Met expression using 18F-labeled binding peptide in human cancer xenografts

Objectives

c-Met is a receptor tyrosine kinase shown inappropriate expression and actively involved in progression and metastasis in most types of human cancer. Development of c-Met-targeted imaging and therapeutic agents would be extremely useful. Previous studies reported that c-Met-binding peptide (Met-pep1, YLFSVHWPPLKA) specifically targets c-Met receptor. Here, we evaluated ¹⁸F-labeled Met-pep1 for PET imaging of c-Met positive tumor in human head and neck squamous cell carcinoma (HNSCC) xenografted mice.

Methods

c-Met-binding peptide, Met-pep1, was synthesized and labeled with 4-nitrophenyl [¹⁸F]-2-fluoropropionate ([¹⁸F]-NPFP) ([¹⁸F]FP-Met-pep1). The cell uptake, internalization and efflux of [¹⁸F]FP-Met-pep1 were assessed in UM-SCC-22B cells. In vivo pharmacokinetics, blocking and biodistribution of the radiotracers were investigated in tumor-bearing nude mice by microPET imaging.

Results

The radiolabeling yield for [¹⁸F]FP-Met-pep1 was over 55% with 97% purity. [¹⁸F]FP-Met-pep1 showed high tumor uptake in UM-SCC-22B tumor-bearing mice with clear visualization. The specificity of the imaging tracer was confirmed by significantly decreased tumor uptake after co-administration of unlabeled Met-pep1 peptides. Prominent uptake and rapid excretion of [¹⁸F]FP-Met-pep1 was also observed in the kidney, suggesting this tracer is mainly excreted through the renal-urinary routes. Ex vivo biodistribution showed similar results that were consistent with microPET imaging data.

Conclusions

These results suggest that ¹⁸F-labeled c-Met peptide may potentially be used for imaging c-Met positive HNSCC cancer in vivo and for c-Met-targeted cancer therapy.

Invasion-Related Factors as Potential Diagnostic and Therapeutic Targets in Oral Squamous Cell Carcinoma-A Review

It is well recognized that the presence of cervical lymph node metastasis is the most important prognostic factor in oral squamous cell carcinoma (OSCC). In solid epithelial cancer, the first step during the process of metastasis is the invasion of cancer cells into the underlying stroma, breaching the basement membrane (BM)—the natural barrier between epithelium and the underlying extracellular matrix (ECM). The ability to invade and metastasize is a key hallmark of cancer progression, and the most complicated and least understood. These topics continue to be very active fields of cancer research. A number of processes, factors, and signaling pathways are involved in regulating invasion and metastasis. However, appropriate clinical trials for anti-cancer drugs targeting the invasion of OSCC are incomplete. In this review, we summarize the recent progress on invasion-related factors and emerging molecular determinants which can be used as potential for diagnostic and therapeutic targets in OSCC.

High expression of c-Met and EGFR is associated with poor survival of patients with glottic laryngeal squamous cell carcinoma

The present study was undertaken to explore the association between the expression of hepatocyte growth factor receptor (c-Met) and epidermal growth factor receptor (EGFR) with clinicopathological factors and survival status, to obtain prognostic biomarkers in patients with glottis laryngeal squamous cell carcinoma (GLSCC). The expression status of c-Met and EGFR protein was analyzed in 71 archival laryngeal cancer samples by immunohistochemistry. Statistical methods, including univariate and multivariate Cox regression analysis, were used to determine risk factors of progression. In addition, survival analysis was performed by the Kaplan-Meier method. The present study detected positive expression of c-Met and EGFR in 69.0 and 91.5% of GLSCC samples, respectively. The median disease-free survival (DFS) and overall survival (OS) times of all patients were 42.4 and 81.8 months, respectively, and the 2-year DFS and OS rates were 60.1 and 84.91%, respectively. Univariate Cox regression analysis revealed that patients with high expression of EGFR or c-Met had a predisposition for tumor recurrence. The expression of c-Met expression was significantly associated with that of EGFR (P=0.001). High expression of c-Met or EGFR was associated with shorter DFS and OS times. Findings of the multivariate Cox regression analysis indicated that c-Met-expression may be used as an independent predictor of DFS and OS (P=0.002 and P=0.008, respectively). However, EGFR expression was not an independent predictor for DFS and OS (P=0.352 and P=0.24, respectively). The high expression of c-Met and EGFR was associated with poor survival and are important predictors for prognosis of patients with GLSCC.

Hepatocyte Growth Factor/c-Met Signaling in Head and Neck Cancer and Implications for Treatment

Aberrant signaling of the hepatocyte growth factor (HGF)/c-Met pathway has been identified as a promoter of tumorigenesis in several tumor types including head and neck squamous cell carcinoma (HNSCC). Despite a relatively low c-Met mutation frequency, overexpression of HGF and its receptor c-Met has been observed in more than 80% of HNSCC tumors, with preclinical and clinical studies linking overexpression with cellular proliferation, invasion, migration, and poor prognosis. c-Met is activated by HGF through a paracrine mechanism to promote cellular morphogenesis enabling cells to acquire mesenchymal phenotypes in part through the epithelial-mesenchymal transition, contributing to metastasis. The HGF/c-Met pathway may also act as a resistance mechanism against epidermal growth factor receptor (EGFR) inhibition in advanced HNSCC. Furthermore, with the identification of a biologically distinct subset of HNSCC tumors acquired from human papillomavirus (HPV) infection that generally portends a good prognosis, high expression of HGF or c-Met in HPV-negative tumors has been associated with worse prognosis. Dysregulated HGF/c-Met signaling results in an aggressive HNSCC phenotype which has led to clinical investigations for targeted inhibition of this pathway. In this review, HGF/c-Met signaling, pathway alterations, associations with clinical outcomes, and preclinical and clinical therapeutic strategies for targeting HGF/c-Met signaling in HNSCC are discussed.

Vascular endothelial growth factor-targeted paclitaxel-loaded liposome microbubbles and inhibition of human epidermoid-2 cell proliferation

BACKGROUND

Vascular endothelial growth factor (VEGF) plays an important role in the formation of capillary blood vessels. The purpose of this study was to evaluate the inhibitory effect of VEGF-targeted paclitaxel (PTX)-loaded liposome microbubbles (VTPLLMs) on the proliferation of human epidermoid (Hep-2) laryngeal squamous cell carcinoma (SCC).

METHODS

Six groups were randomly divided. The inhibitory effects on Hep-2 proliferation were assessed by a methylthiazol tetrazolium (MTT) method. The cell cycle distributions were investigated by flow cytometry. The expression variations of VEGF and caspase-3 were compared by Western blotting.

RESULTS

Proliferation of Hep-2 in the VTPLLM+ultrasound group was significantly inhibited, and flow cytometry showed that the Hep-2 cells were significantly blocked at stage G2/M compared with other groups. Moreover, Western blotting showed VEGF expression was downregulated and caspase-3 expression was upregulated.

CONCLUSION

VTPLLMs can efficiently inhibit tumor cell proliferation and outperform nontargeted microbubbles or PTX. © 2017 Wiley Periodicals, Inc. Head Neck 39: 656-661, 2017.

Targeting pathways mediating resistance to anti-EGFR therapy in squamous cell carcinoma of the head and neck

INTRODUCTION

As epidermal growth factor receptor (EGFR) is overexpressed in approximately 90% of squamous cell carcinomas of the head and neck (SCCHN), several therapeutic agents that target EGFR have been evaluated for the treatment of SCCHN. Although patients with SCCHN derive clinical benefit from anti-EGFR agents, most notably the EGFR monoclonal antibody cetuximab, these patients eventually become resistant to EGFR-based therapies; preclinical studies have shown activation of secondary signaling pathways that lead to resistance to EGFR inhibition and, as such, serve as potential therapeutic targets to overcome resistance to EGFR inhibitors.

AREAS COVERED

This review summarizes the results of recently completed trials of anti-EGFR agents in SCCHN, highlights the various mechanisms that drive resistance to EGFR inhibitors in SCCHN, and focuses on several novel targeted agents that could potentially help overcome resistance to EGFR-based therapies in SCCHN. Expert commentary: Due to the development of resistance to EGFR-targeted therapies, novel treatment approaches to overcome resistance are a key unmet need for SCCHN.

The association between thyroid volume, L-thyroxine therapy and hepatocyte growth factor levels among patients with euthyroid and hypothyroid goitrous and non-goitrous Hashimoto's thyroiditis versus healthy subjects

OBJECTIVE

Hashimoto's thyroiditis (HT) is the most common etiology of hypothyroidism in regions where iodine deficiency is not a concern. To date, many clinical investigations have been conducted to elucidate its pathogenesis. Several growth factors have been shown to have a role in its development. Hepatocyte growth factor (HGF) is one of the aforementioned molecules. We aimed to demonstrate whether HGF is responsible for HT and goiter development. Also, we aimed to test the hypothesis that levo-thyroxine sodium therapy will suppress HGF levels.

MATERIALS AND METHODS

Sixty-one premenopausal women who were admitted to our outpatient clinic between November 2010 and September 2011 were enrolled. Three groups were determined according to their thyroid function tests (TFTs) as euthyroid Hashimoto's, control and subclinical hypothyroid Hashimoto's groups. Basal TFTs, anti-thyroid peroxidase (anti-TPO), anti-thyroglobulin (anti-tg), thyroid ultrasonography (USG) and HGF were studied and recorded. Subclinical hypothyroid HT patients received levo-thyroxine sodium replacement therapy, and were re-assessed for the same laboratory and radiologic features after a median 3.5 month follow-up.

RESULTS

Basal HGF levels were not different between groups. In the subclinical hypothyroidism group, HGF levels (752.75 ± 144.91 pg/ml vs. 719.37 ± 128.05 pg/ml; p = 0.496) and thyroid volumes (12.51 ± 3.67 cc vs. 12.18 ± 4.26 cc; p = 0.7) before and after treatment did not change significantly. No correlations were found between HGF and other parameters. HGF levels were similar between subjects with nodular goiter and normal thyroid structure.

CONCLUSIONS

HGF was not shown to be associated with HT and goiter development. In addition, levo-thyroxine sodium replacement therapy did not alter serum HGF levels significantly.

Oncogenes and tumor suppressor genes in squamous cell carcinoma of the tongue in young patients

Objectives

The occurrence of squamous cell carcinoma of the tongue (SCCT) of young patients increased. There are still controversies about patient prognosis. The underlying molecular mechanisms remain unclear.

Methods

276 patients (66 ≤45, 210 >45 years) with SCCT were included. Clinical parameters and survival data were assessed. Oncogenes and tumor suppressors were analyzed via immunohistochemistry (p53, CXCR4, p16, EGFR) and qPCR (CDK4, CDKN2A, TP53, MDM2, AKT1, PIK3CA, NRAS, HRAS, KRAS, HGF, MET, EGF, ATM, BRCA1, E2F1, FHIT, RUNX3, STK11, BCL2, CTNNB1).

Results

The median overall survival was 142 (≤45 years) and 34 months (>45 years) (p < 0.0001; HR [95%CI]: 0.37 [0.30–0.58]). Disease specific survival in patients ≤45 years was with 181 months significantly higher than in patients >45 years (p < 0.0001; HR [95%CI]: 0.33 [0.26–0.57]). Immunhistochemistry visualized a comparable expression of analyzed proteins. QPCR demonstrated in patients ≤45 years a higher expression of genes that are associated with carcinogenesis (CTNNB1, STK11, CDKN2A, HGF, MET) as well as tumor suppressors that constitute an enhanced radio-sensitivity (ATM, BRCA1E2F1, FHIT).

Conclusion

Derogation of the WNT-CTNNB1-STK11 and CDKN2A-HGF-MET pathway can constitute the carcinogenesis, while the higher expression of radio-sensitizers ATM, BRCA1E2F1 and FHIT can explain the better OS/DSS in young patients.

c-MET immunostaining in colorectal carcinoma is associated with local disease recurrence

Background

Increased mesenchymal–epithelial transition factor gene (c-MET) expression in several human malignancies is related to increased tumour progression. The aim of the present study is to explore the relationship between immunohistochemical expression of c-MET in colorectal carcinoma (CRC) and the clinicopathological characteristics and follow up data, to compare the expression of c-MET in primary CRC and its metastasis in lymph nodes and to test its validity as independent prognostic factor.

Methods

Hundred and thirty-five archival CRC and nodal metastases samples were collected from King Abdulaziz University Hospital, Saudi Arabia. Tissue microarrays were constructed and immunohistochemistry was done to detected c-MET protein expression. Appropriate statistical analysis was performed.

Results

High c-MET immunostaining was significantly associated with tumour size larger than 5 cm (p < 0.003) and in left colon subsite (p < 0.05). There was no significant correlation between c-MET protein expression and age, sex, degree of differentiation, tumour invasion, presence of nodal metastasis, lymphovascular invasion, status of surgical resection margin, or presence of distant metastasis. Furthermore, no association between c-MET protein expression and disease free survival. High protein expression of c-MET is associated with the incidence of local disease recurrence (p < 0.012).

Conclusion

c-MET is a new promising target that may help in understanding the pathogenesis of CRC, and to be used as independent prognostic biomarker to predict local disease recurrence in CRC. Further molecular in vitro and in vivo studies are required to pursue c-MET as potential molecular marker of metastases and test the possibility of its incorporation as a new targeted therapeutic target.

Immunoprofile of c-MET/PI3K signaling in human salivary gland tumors

OBJECTIVE

The aim of this study was to analyze the expression pattern of proteins in the HGF/c-MET/PI3K signaling pathway in salivary gland tumors (SGTs) and to correlate the findings with the proliferative index and clinical parameters.

STUDY DESIGN

We assembled tissue microarrays (TMAs) of 108 cases of SGTs, including 69 cases of pleomorphic adenoma (PA), 24 cases of adenoid cystic carcinoma (AdCC), and 15 cases of mucoepidermoid carcinoma (MEC). An immunohistochemical analysis of hepatocyte growth factor (HGF), MET phosphorylation (p-MET), protein kinase B (AKT) phosphorylation (p-AKT), and Ki-67 proteins was performed.

RESULTS

Benign and malignant SGTs presented similar scores of HGF-positive cells (P = .36), whereas, malignant SGTs exhibited higher levels of p-MET (P = .001) and p-AKT (P = .001) than benign SGTs. No correlation of HGF, p-MET, or p-AKT expression was observed with clinical parameters. PA had a lower proliferative index than either AdCC (P = .001) or MEC (P = .001).

CONCLUSIONS

The salivary gland carcinomas exhibited increased activation of the HGF pathway, as evidenced by the phosphorylation of the MET receptor, and increased activation of the PI3K pathway, as indicated by p-AKT. These data suggest that the HGF/c-MET/PI3K signaling pathway is active in SGTs, especially in malignant neoplasms.

Role of met axis in head and neck cancer

Head and neck cancer is the sixth most common type of cancer worldwide. Despite advances in aggressive multidisciplinary treatments, the 5-year survival rate for this dreadful disease is only 50%, mostly due to high rate of recurrence and early involvement of regional lymph nodes and subsequent metastasis. Understanding the molecular mechanisms responsible for invasion and metastasis is one of the most pressing goals in the field of head and neck cancer. Met, also known as hepatocyte growth factor receptor (HGFR), is a member of the receptor protein tyrosine kinase (RPTK) family. There is compelling evidence that Met axis is dysregulated and plays important roles in tumorigenesis, progression, metastasis, angiogenesis, and drug resistance in head and neck cancer. We describe in this review current understanding of Met axis in head and neck cancer biology and development of therapeutic inhibitors targeting Met axis.

Silencing Met receptor tyrosine kinase signaling decreased oral tumor growth and increased survival of nude mice

OBJECTIVES

The hepatocyte growth factor receptor (Met) is frequently overexpressed in Head and Neck Squamous Cell Carcinoma (HNSCC), correlating positively with high-grade tumors and shortened patient survival. As such, Met may represent an important therapeutic target. The purpose of this study was to explore the role of Met signaling for HNSCC growth and locoregional dissemination.

MATERIALS AND METHODS

Using a lentiviral system for RNA interference, we knocked down Met in established HNSCC cell lines that express high levels of the endogenous receptor. The effect of Met silencing on in vitro proliferation, cell survival and migration was examined using western analysis, immunohistochemistry and live cell imaging. In vivo tumor growth, dissemination and mouse survival was assessed using an orthotopic tongue mouse model for HNSCC.

RESULTS

We show that Met knockdown (1) impaired activation of downstream MAPK signaling; (2) reduced cell viability and anchorage independent growth; (3) abrogated HGF-induced cell motility on laminin; (4) reduced in vivo tumor growth by increased cell apoptosis; (5) caused reduced incidence of tumor dissemination to regional lymph nodes and (6) increased the survival of nude mice with orthotopic xenografts.

CONCLUSION

Met signaling is important for HNSCC growth and locoregional dissemination in vivo and that targeting Met may be an important strategy for therapy.

Expression of c-Met Is Different along the Location and Associated with Lymph Node Metastasis of Head and Neck Carcinoma

Background

Activation of the c-Met pathway is involved in cancer progression and the prognosis. We aimed to identify any association of c-Met protein expression with a number of clinicopathologic variables including infection of human papillomavirus and Epstein-Barr virus (EBV) in head and neck carcinomas (HNCa).

Methods

Eighty-two cases were enrolled in this study. Expression of c-Met and p16 was investigated immunohistochemically. EBV was detected by in situ hybridization and amplification of the c-Met gene by fluorescence in situ hybridization.

Results

The c-Met protein was expressed in 41.5% (34/82), and gene amplification was found in 1.4% (1/71). High expression of c-Met was associated with the primary location of the tumor; the hypopharynx showed the highest expression, followed by the oral cavity, larynx, and nasal cavity. Squamous cell carcinoma expressed c-Met more frequently than undifferentiated carcinoma. Also, p16 immunoreactivity or EBV infection was associated with the tumor location and well-differentiated histologic type, but were not linked to c-Met expression. The patients with positive c-Met expression showed frequent lymph node metastasis.

Conclusions

Activation of the c-Met pathway might be involved in a subset of HNCa. Cases showing positive c-Met expression should be carefully monitored because of the high probability of lymph node metastasis.

Targeting MET by tyrosine kinase inhibitor suppresses growth and invasion of nasopharyngeal carcinoma cell lines

Nasopharyngeal carcinoma (NPC) represents a common cancer in endemic areas with high invasive and metastatic potential. It is now known that the HGF-MET signaling pathway plays an important role in mediating the invasive growth of many different types of cancer, including head and neck squamous cell carcinoma. HGF has been shown to stimulate NPC cell growth and invasion in cell line model. The current study aims at demonstrating the effect of MET inhibition by small molecule tyrosine kinase inhibitor PHA665752 on the growth and invasive potential of NPC cell lines. NPC cell lines were used for immunohistochemistry for the MET protein, as well as western blot analysis on MET together with its downstream cascade signaling proteins after treatment with PHA665752. The effect on cell growth, migration and invasion after PHA665752 treatment was also studied. MET inhibition by PHA665752 resulted in highly significant inhibition on NPC cell growth, migration and invasion in vitro. Down-regulation of phospho-MET, phospho-Akt, phospho-MAPK, phospho-STAT3, cyclin D1, β-catenin and PCNA was detected in NPC cells after PHA665752 treatment. MET inhibition with tyrosine kinase inhibitor resulted in suppression of NPC cell growth and invasive potential via down-regulation of a variety of signaling onco-proteins. MET is an important therapeutic target for NPC that warrants further studies and clinical trials.