Tumor hypoxia and role of hypoxia-inducible factor in oral cancer

BACKGROUND

Head and neck cancer (HNC) is one of the most frequent malignancies in Asian males with a poor prognosis. Apart from well-known prognostic indicators, markers of tumor hypoxia can help us predict response to treatment and survival.

METHODS

A review of the literature on the present evidence and potential clinical importance of tumor hypoxia in head and neck cancer was carried out. The data obtained from the literature search is presented as a narrative review.

RESULTS

The literature shows possible associations between prognosis and low tumor oxygenation. Intermediate hypoxia biomarkers like HIF-1, GLUT-1, miRNA, and lactate, can help in predicting the response to therapy and survival as their altered expression is related to prognosis.

CONCLUSIONS

Hypoxia is common in HNC and can be detected by use of biomarkers. The tumors that show expression of hypoxia biomarkers have poor prognosis except for patients with human papilloma virus-associated or VHL-associated cancers. Therapeutic targeting of hypoxia is emerging; however, it is still in its nascent stage, with increasing clinical trials hypoxia is set to emerge as an attractive therapeutic target in HNC.

Concentration of hypoxia-inducible factor-1, glucose transporter 1 and vascular endothelial growth factor in tissue samples and serum in patients with primary laryngeal carcinoma

BACKGROUND

Markers of tumorigenesis are essential factors which may play a major role in the early detection of head and neck carcinoma.

AIMS/OBJECTIVES

To assess concentration of HIF-1, GLUT1 and VEGF in tissue samples and blood serum and its correlation to the tumour size, nodal disease, pathologic differentiation and patients' data.

MATERIAL AND METHODS

Fifty-two patients diagnosed with laryngeal carcinoma stage I-IV in which concentration of HIF-1, GLUT1 and VEGF was assessed in tissue samples and blood serum using immunoassay method.

RESULTS

HIF-1α, GLUT1, VEGF concentration was significantly higher in cancer tissue samples than in normal tissue (p < .001) and benign laryngeal lesions. Serum levels of the factors were significantly lower in the control group. Statistically significant difference regarding tumour size was found between T2 and T4 stages in HIF-1α concentration in cancer samples and serum.

CONCLUSIONS

The results show that high concentration of HIF-1α, GLUT1 and VEGF might be suggestive of carcinogenic process when diagnosing patients with laryngeal lesions and could promote early detection of malignancy.

SIGNIFICANCE

The results of this study show importance of biochemical assessment in malignant tumours which may affect clinical decisions.

Differential HIF2α Protein Expression in Human Carotid Body and Adrenal Medulla under Physiologic and Tumorigenic Conditions

Hypoxia-inducible factors (HIF) 2α and 1α are the major oxygen-sensing molecules in eukaryotic cells. HIF2α has been pathogenically linked to paraganglioma and pheochromocytoma (PPGL) arising in sympathetic paraganglia or the adrenal medulla (AM), respectively. However, its involvement in the pathogenesis of paraganglioma arising in the carotid body (CB) or other parasympathetic ganglia in the head and neck (HNPGL) remains to be defined. Here, we retrospectively analyzed HIF2α by immunohistochemistry in 62 PPGL/HNPGL and human CB and AM, and comprehensively evaluated the HIF-related transcriptome of 202 published PPGL/HNPGL. We report that HIF2α is barely detected in the AM, but accumulates at high levels in PPGL, mostly (but not exclusively) in those with loss-of-function mutations in VHL and genes encoding components of the succinate dehydrogenase (SDH) complex. This is associated with upregulation of EPAS1 and the HIF2α-regulated genes COX4I2 and ADORA2A. In contrast, HIF2α and HIF2α-regulated genes are highly expressed in CB and HNPGL, irrespective of VHL and SDH dysfunctions. We also found that HIF2α and HIF1α protein expressions are not correlated in PPGL nor HNPGL. In addition, HIF1α-target genes are almost exclusively overexpressed in VHL-mutated HNPGL/PPGL. Collectively, the data suggest that involvement of HIF2α in the physiology and tumor pathology of human paraganglia is organ-of-origin-dependent and HIF1α-independent.

Clinical implications of hypoxia biomarker expression in head and neck squamous cell carcinoma: a systematic review

Awareness increases that the tumor biology influences treatment outcome and prognosis in cancer. Tumor hypoxia is thought to decrease sensitivity to radiotherapy and some forms of chemotherapy. Presence of hypoxia may be assessed by investigating expression of endogenous markers of hypoxia (EMH) using immunohistochemistry (IHC). In this systematic review we investigated the effect of EMH expression on local control and survival according to treatment modality in head and neck cancer (head and neck squamous cell carcinoma [HNSCC]). A search was performed in MEDLINE and EMBASE. Studies were eligible for inclusion that described EMH expression in relation to outcome in HNSCC patients. Quality was assessed using the Quality in Prognosis Studies (QUIPS) tool. Hazard ratios for locoregional control and survival were extracted. Forty studies of adequate quality were included. HIF-1a, HIF-2a, CA-IX, GLUT-1, and OPN were identified as the best described EMHs. With exception of HIF-2a, all EMHs were significantly related to adverse outcome in multiple studies, especially in studies where patients underwent single-modality treatment. Positive expression was often correlated with adverse clinical characteristics, including disease stage and differentiation grade. In summary, EMH expression was common in HNSCC patients and negatively influenced their prognosis. Future studies should investigate the effect of hypoxia-modified treatment schedules in patients with high In summary, EMH expression. These may include ARCON, treatment with nimorazole, or novel targeted therapies directed at hypoxic tissue. Also, the feasibility of surgical removal of the hypoxic tumor volume prior to radiotherapy should be investigated.

Relative quantitative expression of hypoxia-inducible factor-1α, -2α and -3α, and vascular endothelial growth factor A in laryngeal carcinoma

The aim of the present study was to determine the relative quantitative expression of hypoxia-inducible factor (HIF)-1α, -2α and -3α, and VEGF-A in laryngeal carcinoma. A total of 63 patients with carcinoma of the larynx were enrolled in the study. Total RNA was isolated from fresh, frozen normal and tumor tissues of each patient, and quantitative polymerase chain reaction was performed. HIF-1α was upregulated in the majority of patients (44 patients; 69.84%). By contrast, only 7 (11.11%) patients from the whole group displayed HIF-2α overexpression, while the HIF-3α isoform was silenced in the majority of patients (48 patients, 76.19%). A small group of 5 (7.94%) patients exhibited significant overexpression of the HIF-3α isoform. VEGF-A expression was significantly higher (P<0.05) in patients with upregulated HIF-1α (2.72±1.41 RQ) compared with patients without upregulated HIF-1α (1.86±1.46 RQ). There was a moderate positive correlation between mRNA expression levels of HIF-1α and VEGF-A (r_s=0.392; P<0.005). To the best of our knowledge, this study is first to report quantitative data with regard to the expression of all three HIF isoforms in malignant neoplasms. The findings suggest the existence of specific phenotypes of HIF expression in laryngeal carcinoma, where the HIF switch is absent.

Gene and protein expression of glucose transporter 1 and glucose transporter 3 in human laryngeal cancer-the relationship with regulatory hypoxia-inducible factor-1α expression, tumor invasiveness, and patient prognosis

Increased glucose uptake mediated by glucose transporters and reliance on glycolysis are common features of malignant cells. Hypoxia-inducible factor-1α supports the adaptation of hypoxic cells by inducing genes related to glucose metabolism. The contribution of glucose transporter (GLUT) and hypoxia-inducible factor-1α (HIF-1α) activity to tumor behavior and their prognostic value in head and neck cancers remains unclear. The aim of this study was to examine the predictive value of GLUT1, GLUT3, and HIF-1α messenger RNA (mRNA)/protein expression as markers of tumor aggressiveness and prognosis in laryngeal cancer. The level of hypoxia/metabolic marker genes was determined in 106 squamous cell laryngeal cancer (SCC) and 73 noncancerous matched mucosa (NCM) controls using quantitative real-time PCR. The related protein levels were analyzed by Western blot. Positive expression of SLC2A1, SLC2A3, and HIF-1α genes was noted in 83.9, 82.1, and 71.7 % of SCC specimens and in 34.4, 59.4, and 62.5 % of laryngeal cancer samples. Higher levels of mRNA/protein for GLUT1 and HIF-1α were noted in SCC compared to NCM (p < 0.05). SLC2A1 was found to have a positive relationship with grade, tumor front grading (TFG) score, and depth and mode of invasion (p < 0.05). SLC2A3 was related to grade and invasion type (p < 0.05). There were also relationships of HIF-1α with pTNM, TFG scale, invasion depth and mode, tumor recurrences, and overall survival (p < 0.05). In addition, more advanced tumors were found to be more likely to demonstrate positive expression of these proteins. In conclusion, the hypoxia/metabolic markers studied could be used as molecular markers of tumor invasiveness in laryngeal cancer.

[Analysis of HIF-1α and COX-2 expression in tumor stroma and correlation with the degree of neoplasm invasiveness in laryngeal cancer--preliminary study]

INTRODUCTION

Despite extensive research in the field of molecular biology, immunology and histopathology, prognostically unambiguous morphological indicators of the invasiveness of tumor which allow the prediction of disease course in laryngeal cancer have not yet been identified. The aim of this study was to analyze gene and protein expression of HIF-1a and COX-2 in the tumor stroma and to find relationships between clinical and morphological features (pT, G, depth of tumor invasion, plasmalymphocytic infiltration) and certain markers in squamous cell laryngeal carcinoma.

MATERIAL AND METHODS

We analyzed a group of 59 patients with verified squamous cell carcinoma of the larynx. The pathological evaluation was included pTNM classification criteria, depth of invasion according to tumor front grading and degree of morphological differentiation. Quantitative analysis of the amplified product in real time (real-time RT2-PCR) for estimation of mRNA HIF-1a and COX-2 expression in tumor cells were used. The level of HIF-1a and COX-2 protein expression by Western blot analysis was determined.

RESULTS

In studied group of laryngeal cancers significant differences in expression of certain molecules analyzed in tumor tissue and noncancerous epithelium of the larynx have been shown. Increased expression of HIF-1a and COX-2 at both mRNA and protein level was indicator of greater aggressiveness of the tumor, evaluated on the basis of clinical and morphological features in laryngeal squamous cell carcinomas. Tumors with the most invasive growth (pT4 stage, low-differentiated tumors G3, neoplastic infiltration with invasion of cartilage of the larynx) had the highest expression of HIF-1a and COX-2 at the mRNA and protein level.

CONCLUSIONS

The study pointed out the direction for further research to find unambiguous indicators for estimation of tumor invasiveness and the possibility of practical use of HIF-1a and COX-2 mRNA and protein level assessment as important methods for determining the advancement of clinical and morphological changes in laryngeal cancer, thereby selecting an appropriate model of treatment.

Oncofetal protein IMP3: a new diagnostic biomarker for laryngeal carcinoma

An accurate diagnosis of laryngeal squamous cell carcinoma (LSCC) is essential for patient management. The diagnosis of LSCC, especially in superficial biopsies, can present a diagnostic challenge for pathologists. The ability to diagnose LSCC would be greatly improved by the detection of a tumor-associated antigen. IMP3 is an oncofetal protein associated with aggressive and advanced tumors and is specifically expressed in malignant tumors but not found in benign tissues. The aim of this study was to determine the expression and diagnostic value of IMP3 in LSCC to determine whether it can serve as a diagnostic biomarker. A total of 238 cases (laryngectomy, n = 121; biopsy, n = 117) consisting of 11 laryngeal carcinoma in situ/severe dysplasia and 227 invasive LSCC were examined by immunohistochemistry for IMP3 expression. IMP3 showed strong cytoplasmic staining in 217 (92%) of 238 LSCCs regardless of histologic grade. In addition, 58 (89%) of 65 small biopsies (≤5 mm in greatest dimension) containing a minute amount of carcinoma were positive for IMP3. In contrast to malignant tumors, IMP3 expression was not found in any of the adjacent benign squamous epithelium (0/118 cases; 0%), mild or moderate dysplasia (0/139 cases; 0%), or pseudoepitheliomatous hyperplasia (0/99 cases; 0%). In summary, we are the first to describe that IMP3 is a highly sensitive and specific biomarker for LSCC. The expression of IMP3 in LSCC can be used as a positive biomarker to increase the level of confidence in establishing a definitive diagnosis of a malignancy in laryngeal biopsy.

Expression and significance of hypoxia-inducible factor-1α and MDR1/P-glycoprotein in laryngeal carcinoma tissue and hypoxic Hep-2 cells

The present study aimed to evaluate the expression of hypoxia-inducible factor-1α (HIF-1α) and MDR1/P-glycoprotein (P-gp) in human laryngeal squamous cell carcinoma (LSCC) tissues, and also to investigate the regulation of MDR1 gene expression by HIF-1α in Hep-2 cells under hypoxic conditions. The expression of HIF-1α and MDR1/P-gp in human LSCC tissues was examined using immunohistochemistry. The HIF-1α and MDR1 gene expression in the Hep-2 cells was detected using real-time quantitative reverse transcription (QRT)-PCR and western blot analysis under normoxic and hypoxic conditions. In hypoxia, HIF-1α expression was inhibited by RNA interference. HIF-1α and MDR1/P-gp expression was high in the LSCC tissues and was associated with the clinical stage and lymph node metastasis (P<0.05). HIF-1α expression was positively correlated with MDR1/P-gp expression (P<0.01). In the Hep-2 cells, HIF-1α and MDR1/P-gp expression significantly increased in response to hypoxia. The inhibition of HIF-1α expression synergistically downregulated the expression of the MDR1 gene in hypoxic Hep-2 cells. HIF-1α expression is positively correlated with MDR1/P-gp expression in LSCC, and the two proteins may be able to serve as potential biomarkers for predicting the malignant progression and metastasis of LSCC. HIF-1α may be critical for the upregulation of MDR1 gene expression induced by hypoxia in Hep-2 cells.

Prognostic value of hypoxia-inducible factors (angiogenin and endoglin) in open partial laryngectomies: uni- and multivariate analyses

PURPOSE

Advances in transoral laser microsurgery, radiotherapy, and chemotherapy (and their combinations) have reduced the indications for open partial laryngectomies, although they have replaced total laryngectomies in selected advanced or recurrent laryngeal squamous cell carcinomas (LSCCs). Tissue hypoxia in malignancies appears to be strongly associated with tumor cell invasiveness and metastases. Whether hypoxia-inducible factors can contribute to a rational recommendation of open partial laryngectomy should be investigated.

MATERIALS AND METHODS

Fifty consecutive patients who had undergone primary open partial laryngectomy (supraglottic and supracricoid laryngectomies) were investigated, measuring the immunohistochemical expression of the hypoxia-inducible proteins angiogenin and endoglin in their primary LSCCs also with image analysis.

RESULTS

Univariate analysis showed a significantly higher recurrence rate (P = .007) and shorter disease-free survival (P = .0047) in patients with LSCC with endoglin expression more than 9.0%. Multivariate analysis found endoglin expression independently prognostic in terms of disease-free survival (P = .012). Angiogenin expression (in carcinoma or endothelial cells) was not associated with prognosis.

CONCLUSIONS

Endoglin should be further studied as a biomarker of patients with LSCC at higher risk for recurrence after open partial laryngectomy who may benefit from more aggressive treatments. Endoglin expression in positive laryngeal biopsies may prove useful as a parameter for choosing between different surgical and multimodality approaches to controversial LSCC cases.

Expression and significance of hypoxia-inducible factor-1α and survivin in laryngeal carcinoma tissue and cells

OBJECTIVE

The aim was to evaluate hypoxia-inducible factor-1α (HIF-1α) and survivin expression in laryngeal squamous cell carcinoma (LSCC) tissues and cell lines and to investigate whether HIF-1α has an effect on the regulation of survivin gene expression in LSCC cells under hypoxia.

STUDY DESIGN

Prospective, observational.

SETTING

Shanghai Jiaotong University Affiliated First People's Hospital.

SUBJECTS AND METHODS

The expression of HIF-1α and survivin protein in human LSCC tissues was analyzed by immunohistochemistry. HIF-1α and survivin gene expression levels in Hep-2 cells were detected by real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) and Western blot under normoxic or hypoxic conditions. In hypoxic cells, HIF-1α expression was inhibited by RNA interference.

RESULTS

HIF-1α and survivin were both highly expressed in LSCC tissues and significantly related to the clinical stage and lymph node metastasis (P < .05). Meanwhile, a positive correlation existed between HIF-1α and survivin expression (r = 0.456, P < .01). In LSCC cells, HIF-1α and survivin expression were obviously upregulated in response to hypoxia (P < .05). The downregulation of HIF-1α expression dramatically decreased survivin gene expression in hypoxic cells (P < .05).

CONCLUSION

HIF-1α could be considered as an important regulator for the upregulation of survivin gene expression induced by hypoxia in LSCC cells, and both proteins could be regarded as 2 key predictors of malignant progression and metastasis of LSCC.

Hypoxia in head and neck squamous cell carcinoma

Hypoxia is a common feature in most of the solid tumors including head and neck squamous cell carcinoma (HNSCC). Hypoxia reflects the imbalance between oxygen consumption by the rapidly proliferating cancer cells and the insufficient oxygen delivery due to poor vascularization and blood supply. The hypoxic microenvironment in the HNSCC contributes to the development of aggressive carcinoma phenotype with high metastatic rate, resistance to therapeutic agents, and higher tumor recurrence rates, leading to low therapeutic efficiency and poor outcome. To overcome the therapeutic resistance due to hypoxia and improving the prognosis of the HNSCC patients, many approaches have been examined in laboratory studies and clinical trials. In this short paper, we discuss the mechanisms involved in the resistance of radiotherapy and chemotherapy in hypoxic condition. We also exploit the molecular mechanisms employed by the HNSCC cells to adapt the hypoxic condition and their tumorigenic role in head and neck, as well as the strategies to overcome hypoxia-induced therapeutic resistance.

Expression and significance of hypoxia-inducible factor-1α and glucose transporter-1 in laryngeal carcinoma

Malignant cells show increased glucose uptake in vitro and in vivo. This process is considered to be mediated by glucose transporters (GLUTs). Hypoxia-inducible factor-1α (HIF-1α) may upregulate GLUT-1 expression. Little is known about the correlation between HIF-1α and GLUT-1 expression in laryngeal carcinoma. The current study investigated this correlation immunohistochemically, according to various clinical and pathological features, in 49 paraffin-embedded archival tissue blocks from patients with laryngeal squamous cell carcinoma. HIF-1α and GLUT-1 expression was detected in 63.3 (31/49) and 55.1% (27/49) of the tumour samples, respectively. HIF-1α expression was significantly correlated with lymph node classification (P=0.018), recurrence (P=0.02) and metastasis (P=0.031). GLUT-1A expression was significantly associated with recurrence (P=0.02) and metastasis (P=0.01). Univariate analyses revealed that HIF-1α (χ(2)=8.2; P=0.004) and GLUT-1 expression (χ(2)=9.0; P=0.003) were significantly associated with a poorer survival rate. In a multivariate analysis, GLUT-1 expression (P=0.006) was a significant predictor of poor survival rate, as well as the primary tumour site, lymph node invasion and distant metastasis. Based on Spearman's analysis, GLUT-1 expression and phosphatidylinositol 3-kinase (PI3K) expression were significantly correlated (r=0.504; P=0.000). This is the first study to demonstrate a significant correlation between GLUT-1 and HIF-1α expression in laryngeal carcinoma and to show increased GLUT-1 expression as an independent survival rate predictor. These results suggest that GLUT-1 is a potential new therapeutic target for laryngeal carcinoma.

Potential prognostic and therapeutic role for angiogenesis markers in laryngeal carcinoma

Angiogenesis is a hallmark of cancer, fundamental to its growth. The 'angiogenic switch' occurs when pro-angiogenic factors are not balanced by anti-angiogenic factors. A correlation between angiogenic properties and oncological prognosis (for laryngeal squamous cell carcinoma (LSCC) too) was first hypothesized in the 1990s. An exhaustive literature review was performed to investigate available data on angiogenesis markers and their biological role and therapeutic potential in LSCC. The prognostic significance of microvascular density in LSCC was investigated with endothelial targets, e.g. CD105, CD34, and CD31. Epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), VEGF receptor 2, angiogenin, hypoxia-inducible factor 1, and other biological markers were also studied. Only anti-EGFR therapy has been approved by the USFood and Drug Administration (FDA) for head and neck carcinoma in recent years, while several agents interfering with VEGF and its receptors are being studied. Experimental findings indicate that anti-CD105 monoclonal antibodies efficiently inhibit tumor angiogenesis. There are two main ways to approach the vascular profile of solid malignancies: by inhibiting new vessel formation (anti-angiogenic therapy) or selectively damaging neoplastic vessels (vascular targeting therapy). In advanced LSCC, both these strategies seem promising and warrant further preclinical and clinical investigation.

Expression of hypoxia inducible factor-1α and its significance in laryngeal carcinoma

This study examined levels of hypoxia inducible factor-1α (HIF-1α) protein in 40 laryngeal squamous cell carcinoma specimens using immunohistochemistry. Correlations between HIF-1α immunoreactivity and patient age, tumour lymph node metastasis stage, histological grade (extent of differentiation), and alcohol and smoking history were evaluated. Of the tumour tissues obtained, 35 (87.5%) were located in the glottic area and five (12.5%) in the supraglottic area. All patients were male and aged between 35 and 71 years; 12 (30.0%) presented with lymph node metastases, 24 (60.0%) had cancer classified as T(1) or T(2), and 16 (40.0%) as high clinical stage (T(3) or T(4)). The pattern of HIF-1α protein localization in tumour tissues, when present, was mixed nuclear/cytoplasmic, with positive HIF-1α expression in 27 patients (67.5%). Differences in HIF-1α levels in samples from different tumour stages and in those with lymph node-positive versus lymph node-negative cancers were statistically significant.

Increase in gene dosage is a mechanism of HIF-1alpha constitutive expression in head and neck squamous cell carcinomas

The HIF-1alpha protein plays a key role in the cellular response to hypoxia via transcriptional regulation of genes involved in erythropoiesis, angiogenesis, and metabolism. Overexpression of HIF-1alpha is commonly found in solid tumors in significant association with increased patient mortality and resistance to therapy. The predominant mode of HIF-1alpha regulation by hypoxia occurs at the level of protein stability. In addition to hypoxia, HIF-1alpha protein stability and synthesis is regulated by nonhypoxic signals such as inactivation of tumor suppressors and activation of oncogenes. Here, we show that an increase in gene dosage may contribute to HIF-1alpha mRNA and protein overexpression in a nonhypoxic environment in head and neck squamous cell carcinomas (HNSCC). Increased HIF-1alpha gene dosage was found in one out of five HNSCC-derived cell lines and three out of 27 HNSCC primary tumors. Significantly, increased gene dosage in those samples was associated with high HIF-1alpha mRNA and protein levels. Normoxic overexpression of HIF-1alpha protein in HNSCC-derived cell lines was also paralleled by higher expression levels of HIF-1alpha target genes. Array CGH analysis confirmed the copy number increase of HIF-1alpha gene and revealed that the gene is contained within a region of amplification at 14q23-q24.2 both in the cell line and primary tumors. In addition, FISH analysis revealed the presence of 11-13 copies on a tetraploid background in SCC2 cells. These data suggest that increased HIF-1alpha gene dosage is a mechanism of HIF-1alpha protein overexpression in HNSCC that possibly prepares the cells for a higher activity in an intratumoral hypoxic environment.