Elevation of plasma osteopontin level in patients with undifferentiated nasopharyngeal carcinoma

The value of plasma hypoxia markers for predicting imaging-based hypoxia in patients with head-and-neck cancers undergoing definitive chemoradiation

•

Higher osteopontin plasma levels correlate with more hypoxic tumors at baseline.

•

Increased baseline osteopontin levels are associated with residual tumor hypoxia.

•

Absent early hypoxia response is linked with higher VEGF and CTGF levels in week 5.

•

Plasma hypoxic markers may serve as biomarkers favoring radiotherapy personalization.

Background

Methods

Results

Conclusion

Osteopontin: A Key Regulator of Tumor Progression and Immunomodulation

Simple Summary

Anti-PD-1/PD-L1 and anti-CTLA-4-based immune checkpoint blockade (ICB) immunotherapy have recently emerged as a breakthrough in human cancer treatment. Durable efficacy has been achieved in many types of human cancers. However, not all human cancers respond to current ICB immunotherapy and only a fraction of the responsive cancers exhibit efficacy. Osteopontin (OPN) expression is highly elevated in human cancers and functions as a tumor promoter. Emerging data suggest that OPN may also regulate immune cell function in the tumor microenvironment. This review aims at OPN function in human cancer progression and new findings of OPN as a new immune checkpoint. We propose that OPN compensates PD-L1 function to promote tumor immune evasion, which may underlie human cancer non-response to current ICB immunotherapy.

Abstract

OPN is a multifunctional phosphoglycoprotein expressed in a wide range of cells, including osteoclasts, osteoblasts, neurons, epithelial cells, T, B, NK, NK T, myeloid, and innate lymphoid cells. OPN plays an important role in diverse biological processes and is implicated in multiple diseases such as cardiovascular, diabetes, kidney, proinflammatory, fibrosis, nephrolithiasis, wound healing, and cancer. In cancer patients, overexpressed OPN is often detected in the tumor microenvironment and elevated serum OPN level is correlated with poor prognosis. Initially identified in activated T cells and termed as early T cell activation gene, OPN links innate cells to adaptive cells in immune response to infection and cancer. Recent single cell RNA sequencing revealed that OPN is primarily expressed in tumor cells and tumor-infiltrating myeloid cells in human cancer patients. Emerging experimental data reveal a key role of OPN is tumor immune evasion through regulating macrophage polarization, recruitment, and inhibition of T cell activation in the tumor microenvironment. Therefore, in addition to its well-established direct tumor cell promotion function, OPN also acts as an immune checkpoint to negatively regulate T cell activation. The OPN protein level is highly elevated in peripheral blood of human cancer patients. OPN blockade immunotherapy with OPN neutralization monoclonal antibodies (mAbs) thus represents an attractive approach in human cancer immunotherapy.

Increasing incidence of Epstein-Barr virus-related nasopharyngeal carcinoma in the United States

BACKGROUND

The incidence of nasopharyngeal carcinoma (NPC) has been historically low in the United States. Although etiological factors differ by histological subtype, Epstein-Barr virus is accepted as the primary risk factor for nonkeratinizing NPC. In light of the changing epidemiology of viral-associated cancers, it is important to evaluate the temporal incidence of NPC in the United States.

METHODS

Incidence and survival data from 1973 through 2015 were obtained from the Surveillance, Epidemiology, and End Results program. Stratified analyses were conducted to assess temporal trends in NPC by histological subtype, sex, and race. The data were analyzed using SAS and Joinpoint Regression Software to determine age-adjusted incidence rates, determine trends in the annual percent change, and calculate 5-year relative survival estimates and Kaplan-Meier curves.

RESULTS

Although overall NPC incidence is decreasing in the United States, the nonkeratinizing differentiated subtype is starkly increasing, with an annual percent change of approximately 4% among white males (95% CI, 2.5%-5.2%), white females (95% CI, 1.9%-6.2%), and black males (95% CI, 2.0%, 5.7%); 2.7% among black females (95% CI, 0.8%, 4.6%); and 1.8% among women in the "other" race category (95% CI, 0.4%-3.3%). Racial disparities were noted, with 32% of nonkeratinizing NPC cases among blacks occurring before the age of 40 years. In addition, black males displayed consistently worse survival across all histological subtypes, whereas individuals in the "other" race category, particularly females, experienced the highest 5-year relative survival estimates.

CONCLUSIONS

The current results indicate that the Epstein-Barr virus-related, differentiated NPC subtype is increasing across all sexes and races in the United States, with distinct incidence and survival disparities among blacks.

The inhibitory effects of extracellular ATP on the growth of nasopharyngeal carcinoma cells via P2Y2 receptor and osteopontin

Background

Nasopharyngeal carcinoma (NPC) is a common malignant tumor observed in the populations of southern China and Southeast Asia. However, little is known about the effects of purinergic signal on the behavior of NPC cells. This study analyzed the effects of ATP on the growth and migration of NPC cells, and further investigated the potential mechanisms during the effects.

Methods

Cell viability was estimated by MTT assay. Transwell assay was utilized to assess the motility of NPC cells. Cell cycle and apoptosis were detected by flow cytometry analysis. Changes in OPN, P2Y2 and p65 expression were assessed by western blotting analysis or immunofluorescence. The effects of ATP and P2Y2 on promoter activity of OPN were analyzed by luciferase activity assay. The binding of p65 to the promoter region of OPN was examined by ChIP assay.

Results

An MTT assay indicated that ATP inhibited the proliferation of NPC cells in time- and dose-dependent manners, and a Transwell assay showed that extracellular ATP inhibited the motility of NPC cells. We further investigated the potential mechanisms involved in the inhibitory effect of extracellular ATP on the growth of NPC cells and found that extracellular ATP could reduce Bcl-2 and p-AKT levels while elevating Bax and cleaved caspase-3 levels in NPC cells. Decreased levels of p65 and osteopontin were also detected in the ATP-treated NPC cells. We demonstrated that extracellular ATP inhibited the growth of NPC cells via p65 and osteopontin and verified that P2Y2 overexpression elevated the inhibitory effect of extracellular ATP on the proliferation of NPC cells. Moreover, a dual luciferase reporter assay showed that the level of osteopontin transcription was inhibited by extracellular ATP and P2Y2. ATP decreased the binding of p65 to potential sites in the OPN promoter region in NPC cells.

Conclusion

This study indicated that extracellular ATP inhibited the growth of NPC cells via P2Y2, p65 and OPN. ATP could be a promising agent serving as an adjuvant in the treatment of NPC.

Correlation between OPN gene polymorphisms and the risk of nasopharyngeal carcinoma

Previous studies suggest that osteopontin (OPN) levels are associated with the incidence and development of multiple types of cancer. This study analyzes the correlation between OPN gene variants and nasopharyngeal carcinoma (NPC). A total of 150 NPC patients and 150 healthy adults were enrolled and divided into NPC and control groups. In both groups, four OPN polymorphisms including rs1126772, rs4754, rs11728697 and rs9138 were quantitatively genotyped by SNaPshot SNP genotyping assay. Allele frequencies of four OPN polymorphisms were compared between two groups. No statistical significance was noted regarding genotype frequency of four OPN polymorphisms between male NPC and healthy subjects (all P > 0.05). Female subjects between two groups significantly differed in terms of genotype frequency of rs1172869 (P = 0.002). No statistical significance was observed in allele frequencies in each of four OPN polymorphisms between two groups (all P > 0.05). For NPC patients, the polymorphisms information content (PIC) ranged from 0.2961 to 0.3584 and 0.3047 to 0.3655 for normal controls. Additionally, rs11728697 had the highest effective number of alleles (Ne), expected heterozygosity (HE) and PIC in two groups. Female subjects in two groups significantly differed in the genotype frequency of rs1172869 while no statistical significance was noted for male counterparts. All subjects in the NPC and control groups had similar allele frequency. All the four OPN polymorphisms were moderately polymorphic. The mean NA, Ne, Ho, He and PIC of each OPN polymorphism in the control group were higher than those in the NPC group without a significant difference.

Serum levels of osteopontin as a prognostic factor in patients with oral squamous cell carcinoma

Osteopontin (OPN) is a multifunctional glycophosphoprotein that was detected in many carcinomas, and it may have a prognostic role. The aim of this study was to determine osteopontin serum levels in patients with oral squamous cell carcinoma (OSCC) and investigated its correlation with clinicopathological features of tumor. Using an ELISA kit, we assessed and compared the circulating levels of OPN in blood serum of 45 oral squamous cell carcinoma patients with 45 healthy control samples. The serum osteopontin level in patients with OSCC was significantly higher (145.8 ± 14.6 ng/ml, n = 45) compared with the healthy controls (53.9 ± 9.6 ng/ml, n = 45, p < 0.001). Mean serum osteopontin level was significantly higher in patients with nodal metastasis (p = 0.03) and higher stage (p = 0.02). Findings of the present study suggest that OPN may have a potential role in pathogenesis of OSCC and it may be used as a tool for monitoring tumor progression.

Association of osteopontin polymorphisms with nasopharyngeal carcinoma risk

No previous study has reported the association of osteopontin polymorphisms with nasopharyngeal carcinoma (NPC) risk. We aimed to investigate the association in a Chinese population. Four variants of osteopontin, rs11730582, rs1126772, rs9138, and rs4754 polymorphisms, were assessed in a case-control study which consists of 108 NPC patients and 210 health controls, by using polymerase chain reaction--restriction fragment length polymorphism method. Serum osteopontin levels were measured by enzyme-linked immunosorbent assay. The serum osteopontin levels were significantly higher in NPC patients than those in controls (P<0.01). Carriers of CC and CT genotype of rs11730582 presented lower serum osteopontin levels than those of TT genotype carriers (P<0.05). Genotypes CT and CT+CC of rs11730582 were associated with the risk of NPC (CT:OR = 0.57, 95%CI = 0.34-0.94; CC+CT:OR = 0.54, 95%CI = 0.34-0.87). Haplotype analysis revealed that haplotype T-A-A-C of rs11730582, rs1126772, rs9138, and rs4754 was associated with NPC risk (OR = 0.49, 95%CI = 0.27-0.86). Stratification analysis showed that genotypes CT and CT+CC of rs11730582 were associated with tumor stage and lymph node metastasis (P<0.05). No associations were found between rs1126772, rs9138, and rs4754 polymorphisms and NPC risk (P>0.05). The variant rs11730582 of osteopontin is associated with NPC risk. It potentially serves as a genetic marker of NPC predisposition.

Elevated circulating levels of osteopontin are associated with metastasis in advanced non-small cell lung cancer

OBJECTIVE

To investigate the relationship between postoperative metastasis and circulating levels of osteopontin in non-small cell lung cancer (NSCLC).

METHODS

The expression of osteopontin mRNA were detected with RT-PCR technique. The circulating levels of osteopontin were measured through ELASA in 46 NSCLC cases that had not been received any anti-cancer treatment at the time of sampling. The tissues from fifteen patients with benign pulmonary diseases were studied as control group.

RESULTS

The overall median mRNA expression level of osteopontin was approximately 70-fold higher in tumor tissues than in matched normal lung tissues (P<0.001). Over-expression of osteopontin mRNA was significantly associated with clinical stage (P=0.009). Advanced disease states had higher circulating level of osteopontin (stage I+II versus stage III+VI). In multivariate analysis, stage was the only independent factor influencing circulating levels of osteopontin. All patients were followed up for 12 months, 2 of the 46 patients with both osteopontin mRNA expression and elevated plasma osteopontin levels had local recurrence and 10 had distant metastasis. There was a significant difference in the osteopontin levels between metastasis group and non-metastasis group.

CONCLUSION

Preoperative plasma levels of osteopontin are significantly associated with post-operative metastasis in advanced NSCLC.

Suramin inhibits the growth of nasopharyngeal carcinoma cells via the downregulation of osteopontin

Radiotherapy is the principal therapy for nasopharyngeal carcinoma (NPC) at early stages. A number of chemotherapeutic methods have been used to inhibit the progression of NPC at elevated stages. Suramin has been reported to inhibit the growth of certain tumor cells via various pathways. In the present study, we aimed to analyze the effects of suramin on the proliferation of NPC cells (CNE-2). Suramin was proved to demonstrate NPC cell growth-inhibiting effects both in a dose- and time-dependent manner. To determine the potential mechanisms of these effects, western blotting and flow cytometric analysis were performed. Suramin was found to have the potential to induce cell cycle arrest in S-phase CNE-2 cells. Additionally, we found that the OPN level may decrease in suramin-treated CNE-2 cells. The changes of certain apoptosis- and p-AKT-associated proteins possibly regulating the OPN expression were measured by western blotting. In conclusion, suramin may function as a potential agent for the adjunctive therapy of NPC.

Comprehensive study on the prognostic role of osteopontin expression in oral squamous cell carcinoma

Osteopontin is a tumor-associated protein that promotes tumor development and metastasis. The preoperative blood samples of 94 oral squamous cell carcinoma (OSCC) patients and 28 healthy individuals were analyzed for plasma osteopontin levels, and another 256 paraffin-embedded OSCC specimens were analyzed by osteopontin immunostaining. The patients with advanced tumor (T) stage (T3/T4 vs. T1/T2) and positive nodal (N) status had significantly higher plasma levels of osteopontin (both p<0.001). Positive osteopontin immunostaining also correlated significantly with advanced T stage (p<0.001), positive N status (p<0.001), advanced TNM stage (p<0.001) and male gender (p=0.016). Unfavorable cumulative 5-year overall survival rates correlated significantly with positive osteopontin immunostaining (p<0.001), advanced T stage (p<0.001), positive N status (p<0.001) and advanced TNM stage (p<0.001). However, Cox regression analysis revealed that T stage and N status were independent prognostic factors for survival (both p<0.001) and osteopontin immunostaining was marginally significant for survival (p=0.056). The present study demonstrated that high expression level of osteopontin in either the plasma or the tumor of the patients with OSCC was associated with tumor progression, suggesting that osteopontin expression is an important prognostic factor for OSCC.

Clinical significance of osteopontin expression in T1 and T2 tongue cancers

BACKGROUND

Osteopontin (OPN) is considered to be a tumor-related protein associated with tumor aggressiveness and metastasis.

METHODS

Immunohistochemistry was used to study the clinical significance of OPN expression in T1 and T2 tongue cancers.

RESULTS

Positive OPN expression significantly correlated with higher tumor classification (T) (p = .004), positive nodal classification (N) (p < .001), greater tumor thickness (p < .001), and presence of tumor necrosis (p = .016), respectively. The unfavorable cumulative 5-year disease-free survival rate significantly correlated with positive OPN expression (p < .001), T2 (p = .024), positive N (p < .001), greater tumor thickness (p = .023), and positive tumor necrosis (p = .003). However, taking CD105 into consideration, only CD105 expression was the independent prognostic factor for survival by Cox's regression analysis.

CONCLUSION

Overexpression of OPN in the tumors implicated a more aggressive tumor behavior and was an important factor for survival. In addition, there might be relationship between OPN and CD105 expressions in angiogenesis.

Elevated plasma osteopontin as marker for distant metastases and poor survival in patients with renal cell carcinoma

PURPOSE

To evaluate diagnostic and prognostic significance of plasma osteopontin (OPN) in patients with renal cell carcinoma (RCC).

METHODS

The retrospective study included 80 patients with RCC (pN0M0, n = 32; pN1M0, n = 11; M1, and n = 37), and 52 healthy controls (27 females and 25 males). OPN, the bone marker bone-specific alkaline phosphatase (bALP) and carboxyterminal telopetide of type-I collagen (ICTP), and the enzymes alanine aminotransferase (ALAT), and gamma-glutamyltransferase (GGT) were evaluated together with Memorial Sloan-Kettering Cancer Center (MSKCC) laboratory parameters. Data were analyzed by receiver-operating characteristics (ROC), survival analysis, and Cox proportional hazards regression model.

RESULTS

OPN and ICTP levels in RCC patients with distant metastases were significantly elevated (medians 115 and 4.7 microg/l, P < 0.001) compared to those without metastases (31.1 and 2.5 microg/l) and controls (28.9 and 2.1 microg/l) but did not differ between patients with bone or non-bone metastases. Both bALP and ALAT were not different between all study groups, while GGT was only increased in patients with non-bone metastases. In ROC analysis, OPN showed the best discrimination between patients with and without metastases (area under the curve: 0.888). High OPN values were associated with poor survival (Kaplan-Meier analysis, log-rank test, P = 0.002). Multivariate Cox regression with forward and backward stepwise elimination confirmed plasma OPN as independent predictive survival factor in RCC patients.

CONCLUSIONS

Our results show that high plasma OPN levels are associated with distant metastases and poor survival in RCC patients. The use of OPN as potential marker to monitor new treatment strategies in patients with advanced RCC should be evaluated in prospective studies.

Osteopontin: an emerging therapeutic target for anticancer therapy

Distant migration of malignant cells or metastasis is considered one of the hallmarks of tumour progression and makes cancer a most deadly disease. The elevated expression of osteopontin (OPN), a metastasis-associated small integrin-binding ligand N-linked glycoprotein family member has been observed in several cancers and, thus, this protein is considered as a potent prognostic marker during tumour progression. OPN regulates a series of signalling cascades and augments the expression of several oncogenic molecules. Therefore, understanding the molecular mechanism and the signalling pathways by which OPN promotes tumorigenesis may be helpful in designing a novel anticancer therapy. At present, the role of OPN in regulating cancer progression is the subject of intense investigation and targeting OPN might be an appropriate therapeutic strategy for the treatment of cancer. This review is focused on OPN-based anticancer therapy, which may provide a new dimension for the successful treatment of cancer.

Nasopharyngeal carcinoma: molecular biomarker discovery and progress

Nasopharyngeal carcinoma (NPC) is a rare malignancy in most part of the world and it is one of the most confusing, commonly misdiagnosed and poorly understood diseases. The cancer is an Epstein-Barr virus-associated malignancy with a remarkable racial and geographical distribution. It is highly prevalent in southern Asia where the disease occurs at a prevalence about a 100-fold higher compared with other populations not at risk. The etiology of NPC is thought to be associated with a complex interaction of genetic, viral, environmental and dietary factors. Thanks to the advancements in genomics, proteomics and bioinformatics in recent decades, more understanding of the disease etiology, carcinogenesis and progression has been gained. Research into these components may unravel the pathways in NPC development and potentially decipher the molecular characteristics of the malignancy. In the era of molecular medicine, specific treatment to the potential target using technologies such as immunotherapy and RNAi becomes formulating from bench to bedside application and thus makes molecular biomarker discovery more meaningful for NPC management. In this article, the latest molecular biomarker discovery and progress in NPC is reviewed with respect to the diagnosis, monitoring, treatment and prognostication of the disease.

Plasma osteopontin levels in patients with head and neck cancer and cervix cancer are critically dependent on the choice of ELISA system

BACKGROUND

The tumor-associated glycoprotein osteopontin (OPN) is discussed as a plasma surrogate marker of tumor hypoxia and as an indicator of the presence of pleural mesothelioma in asbestos-exposed individuals. The clinical introduction of plasma OPN measurements requires the availability of a reliable enzyme-linked immunosorbence assay (ELISA).

METHODS

We compared previously described and currently available ELISA systems on 88 archival plasma samples obtained from patients with head and neck or cervix cancer between 20 days before and 171 after the start of radiotherapy.

RESULTS

Median (range) plasma OPN levels were 667 (148.8-2095) ng/ml and 9.8 (3.5-189.5) ng/ml for a previously described and a newly marketed assay, respectively. Although results for different assays were significantly correlated (r = 0.38, p < 0.05, Spearman rank test), between-assay factors ranged from 2.0 to 217.9 (median 74.6) in individual patients. OPN levels in cervix cancer patients were comparable to those of head and neck cancer patients.

CONCLUSION

Commercially available OPN ELISA systems produce different absolute plasma OPN levels, compromising a comparison of individual patient data with published results. However, different assays appear to have a similar capacity to rank patients according to plasma OPN level. A review of literature data suggests that plasma OPN levels measured even with identical ELISA systems can only be compared with caution.