Correlation of osteopontin protein expression and pathological stage across a wide variety of tumor histologies

Serum level of osteopontin as a prognostic factor in patients who underwent surgical resection for non-small-cell lung cancer

BACKGROUND

OPN is a multifunctional glycophosphoprotein originally described as a secreted protein from malignant epithelial cells. This study focused on the clinical significance of preoperative serum level of OPN in NSCLC patients who underwent a complete resection.

PATIENTS AND METHODS

The serum OPN level was assayed in 244 patients who underwent a complete resection of NSCLC by commercially available sandwich enzyme-linked immunosorbent assay kits. The patients were considered as a higher group, when the serum OPN levels exceeded 81.3 ng/mL.

RESULTS

The patients included 166 male and 78 female subjects. The histologic types included 172 adenocarcinomas, 49 squamous cell carcinomas, and 23 other types of carcinoma. The serum level of OPN in male patients (92.6 ng/mL) was significantly higher than that of female patients (76.9 ng/mL). The OPN level of squamous cell carcinoma was significantly higher than that of adenocarcinoma. The OPN level was significantly elevated in patients with the pleural invasion or microvascular invasion than those without the invasion. The 5-year survival rate after surgery in the lower OPN group (82.0%) was a significant favorable prognosis than that in the higher OPN group (63.7%) (P < .0001). The 5-year survival rates in the lower OPN group at stage I NSCLC (88.1%) was significantly better than that in the higher OPN group (80.5%) (P = .0321).

CONCLUSION

The preoperative serum OPN level was a useful predictor of an unfavorable prognosis, and it was found to be an independent prognostic determinant of outcome in patients who underwent surgery for NSCLC.

Overexpression of osteopontin, αvβ3 and Pim-1 associated with prognostically important clinicopathologic variables in non-small cell lung cancer

In this study, we examined the expression of osteopontin (OPN), αvβ3 and Pim-1 in non-small cell lung cancer (NSCLC) and investigated the potential clinical implications of their expression patterns in NSCLC. Immunohistochemical assays were used to examine the protein expression of OPN, αvβ3 and Pim-1 in 208 NSCLC samples and their adjacent normal lung tissue specimens. Statistical analyses were performed to evaluate the relationships between OPN, αvβ3 and Pim-1 expression patterns, and their association with the clinical-pathological parameters of NSCLC patients. In NSCLC tissues, the positive rates of OPN, αvβ3 and Pim-1 expression were 67.8% (141/208), 76.0% (158/208) and 58.7% (122/208), respectively. However, in the adjacent normal lung tissues, the positive rates of OPN, αvβ3 and Pim-1 were 20.2% (42/208), 24.0% (50/208) and 14.9% (31/208), respectively. The differences in the positive expression rates of OPN, αvβ3 and Pim-1 between NSCLCs and the adjacent normal lung tissues were all significant (P<0.01). Additionally, the positive expression of OPN, αvβ3 and Pim-1 in NSCLCs was associated with an increase in pathological grade, lymph node metastasis and advanced clinical stage (all P<0.01). Furthermore, associations between the expression of OPN and αvβ3, OPN and Pim-1, and αvβ3 and Pim-1 were also observed in our NSCLC cohort (all P<0.01). The OPN, αvβ3 and Pim-1 proteins are frequently overexpressed in NSCLC and are associated with some clinicopathologic variables that are of known prognostic importance in NSCLC, suggesting that they may play an important role in the development and/or progression of NSCLC.

LIM and SH3 protein 1, a promoter of cell proliferation and migration, is a novel independent prognostic indicator in hepatocellular carcinoma

LIM and SH3 protein 1 (LASP-1) plays a significant role in the formation of several malignant tumours. However, the biological and clinical significances of LASP-1 in hepatocellular carcinoma (HCC) remain largely unknown. Using immunohistochemistry, we analysed LASP-1 expression in 144 clinicopathologically characterised HCC cases. Using gene and transfection and RNA interference, we investigated the effects of LASP-1 overexpression and depletion on tumour cellular behaviour in vitro. LASP-1 expression was detected in not only cytoplasm and but also nucleus of HCC and liver cells. The positive rates of both cytosolic and nuclear LASP-1 expression in HCC were higher than adjacent non-tumourous tissues. Statistical analysis showed that heterogeneous LASP-1 expression is associated with hepatitis B surface antigen (HBsAg) and serum alpha-fetoprotein (AFP) level of HCC patients. A significant trend was identified between cytosolic LASP-1 overexpression in HCC and worsening clinical prognosis. Multivariate survival analysis showed that cytosolic LASP-1 expression was recognised as an independent prognostic factor of patient's survival. In vitro study showed LASP-1 promoted cell proliferation and migration, and resulted in aggressive phenotypes of cancer cells. LASP-1 is a valuable marker of HCC progression. High cytosolic LASP-1 expression is associated with poor overall survival in HCC patients.

Microdensitometry of osteopontin as an immunohistochemical prognostic biomarker in colorectal carcinoma tissue microarrays: potential and limitations of the method in 'biomarker pathology'

AIMS

To explore the potential and limitations of 'biomarker pathology' with quantitative immunohistochemistry on tissue microarrays, taking osteopontin and colorectal carcinoma as a model system.

METHODS AND RESULTS

Microdensitometry for quantitative evaluation of osteopontin immunohistochemistry (clone OP3N) on digital microphotographs using the public domain software ImageJ was observed to be straightforward to perform and reliable. However, using colorectal carcinoma cell lines (n = 11) the correlation between densitometric evaluations of Western blots and microdensitometry of immunocytochemistry of slide cultures was only moderate. A virtual resampling method to simulate tissue microarrays showed that, due to heterogeneity of immunostaining, tumours were misclassified in nearly 20% of the arrays, even if four punches were used. With regard to prognosis, microdensitometric evaluation of a tissue microarray made of a clinicopathologically well-characterized series of colorectal carcinomas with long-term follow-up (222 cases evaluable in the tissue microarray, UICC Stages I-III/R0) showed a moderate survival advantage of patients with high osteopontin expression by microdensitometry.

CONCLUSIONS

These results challenge the basic assumption that microdensitometry is a precise technique for the quantification of proteins detected by immunohistochemistry and delineate drawbacks encountered when working with tissue microarrays in clinicopathological studies.

Hepatocellualar carcinoma serum markers

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in some areas of the world. In most cases, HCC is diagnosed at a late stage. Therefore, the prognosis of patients with HCC is generally poor. The recommended screening strategy for patients with cirrhosis includes the determination of serum α-fetoprotein (AFP) levels and an abdominal ultrasound every 6 months to detect HCC at an earlier stage. AFP, however, is a marker characterized by poor sensitivity and specificity, and abdominal ultrasound is highly dependent on the operator's experience. In addition to AFP, Lens culinaris agglutinin-reactive AFP (AFP-L3), des-γ-carboxy prothrombin (DCP), glypican-3 (GPC-3), osteopontin (OPN), and several other biomarkers (such as squamous cell carcinoma antigen-immunoglobulin M complexes [SCCA-IgM], alpha-1-fucosidase [AFU], chromogranin A [CgA], human hepatocyte growth factor, insulin-like growth factor) have been proposed as markers for the early detection of HCC. For these markers, we describe the mechanisms of production, and their diagnostic and prognosis roles. None of them is optimal; however, when used together, their sensitivity in detecting HCC is increased. Recent research has shown that some biomarkers have mitogenic and migratory activities in the angiogenesis of HCC and are a factor of tumor growth.

The value of plasma osteopontin levels as a predictive factor of disease stage and recurrence in patients with bladder urothelial carcinoma: a prospective study

This study was performed in order to determine the value of plasma osteopontin (OPN) levels as a predictive factor of disease stage and recurrence in patients with bladder urothelial carcinoma (UC). Data from 50 patients diagnosed to have bladder UC after transurethral resection of bladder tumor (TURBT) from 2009 to 2010 were evaluated prospectively. Blood tests were performed before and after TURBT, and plasma OPN levels were measured using enzyme-linked immunosorbent assay. Differences in OPN levels according to clinicopathologic variables were analyzed statistically. Significant differences in plasma OPN levels were observed between groups with and without muscle invasion (89.16 vs. 67.08 ng/mL, p=0.041). Comparison according to tumor grade found no significant difference between high and low grade groups (p=0.115). Mean plasma OPN levels decreased after TURBT without statistical significance (p=0.571). Between groups with recurrence and those without recurrence, OPN levels of the group with recurrence were higher without statistical significance (p=0.161). Comparison of plasma OPN levels according to performance of radical cystectomy (RC) showed significant differences; patients who underwent RC showed higher levels of plasma OPN (95.58 vs. 70.37 ng/mL, p=0.030). Comparison according to T stage after RC showed significant differences in OPN levels (T1: 67.45, T2: 86.60 and T3: 95.23 ng/mL, respectively, p=0.006). The group with lymph node invasion showed significantly higher levels of OPN, compared to the group without invasion (153.24 vs. 68.03 ng/mL, p=0.017). Preoperative plasma OPN levels correlated to muscle invasion of bladder UC and pathological stage after RC.

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.

EGFR expression is linked to osteopontin and Nf-κB signaling in clear cell renal cell carcinoma

AIM AND BACKGROUND

Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase involved in many important aspects of cell biology that are related to tumorigenesis. There are opposite evidences of the role of EGFR in renal cancer and the outcome of EGFR-targeted therapies, suggesting the complexity of EGFR signaling pathways. In vitro, osteopontin (OPN) and nuclear factor kappa B (NF-κB) are thought to be involved in specific ligand-independent EGFR activation that could have a role in resistance to EGFR mAb therapy. Aim of this study was to analyze the relationship between EGFR and OPN at the protein and mRNA level, as well as their relation to NF-κB in clear cell renal cell carcinoma (CCRCC).

MATERIALS AND METHODS

Expression of EGFR, OPN, and p65 NF-κB protein was analyzed using immunohistochemistry and compared mutually in 88 CCRCC samples. Expression of EGFR and OPN mRNAs was analyzed using quantitative Real-time PCR in 22 CCRCC samples and compared mutually and with NF-κB protein expression.

RESULTS

Epidermal growth factor receptor mRNA level was higher in CCRCC samples in comparison with normal renal tissue (p = 0.012) and was associated with high OPN mRNA level, and with NF-κB activation (p < 0.001 and p = 0.045, respectively). Immunohistochemical staining showed the inverse association; high EGFR protein expression was related with low OPN and NF-κB protein expression (p < 0.001 and p = 0.047, respectively).

CONCLUSION

Epidermal growth factor receptor gene is upregulated in CRCC and associated with OPN gene expression and NF-kB signaling. The inverse relation between OPN and EGFR at the protein level could probably reflect dynamic changes that EGFR undergoes following activation.

XELIRI-bevacizumab versus FOLFIRI-bevacizumab as first-line treatment in patients with metastatic colorectal cancer: a Hellenic Cooperative Oncology Group phase III trial with collateral biomarker analysis

Background

The aim was to compare two standard chemotherapy regimens combined with bevacizumab as first-line treatment in patients with metastatic colorectal cancer.

Methods

Patients previously untreated for metastatic disease were randomized in: group A (irinotecan, capecitabine, bevacizumab, every 3 weeks; XELIRI-bevacizumab) and group B (irinotecan, leucovorin, fluorouracil, bevacizumab, every 2 weeks; FOLFIRI-bevacizumab). Primary endpoint was progression-free survival (PFS). Plasma concentrations of nitric oxide, osteopontin, TGF-β1 and VEGF-A were measured at baseline and during treatment.

Results

Among 285 eligible patients, 143 were randomized to group A and 142 to group B. Fifty-five patients (38.5%) in group A and 57 (40.1%) in group B responded (p = 0.81). After a median follow-up of 42 months, median PFS was 10.2 and 10.8 months (p = 0.74), while median OS was 20.0 and 25.3 months (p = 0.099), for groups A and B, respectively. Most frequent grade 3–4 toxicities (group A vs group B) were neutropenia (13% vs 22%, p = 0.053) and diarrhea (19% vs 11%, p = 0.082). Baseline plasma osteopontin concentrations demonstrated prognostic significance for both PFS and OS.

Conclusions

This trial did not show significant differences in efficacy between the groups. However, the toxicity profile was different. Baseline plasma osteopontin concentrations demonstrated independent prognostic significance. (Registration number: ACTRN12610000270011)

Osteopontin's colocalization with the adhesion molecule CEACAM5 in cytoplasm of carcinoma of tongue and its correlation with the invasion of that diease

The purpose of this study was to investigate the expression of carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) and correlate it with OPN expression and function in squamous carcinoma of tongue.Paraffin were sections of 80 samples with squamous carcinoma of tongue and 40 samples with normal tissue of tongue for benign lesion having undergone surgery. Immunohistochemistry (IHC) was used to study the distribution of CEACAM5 and OPN, and double-labeling immunohistochemistry was used to observe the relationship between CEACAM5 and OPN expression.CEACAM5 and OPN are found in normal tissue of tongue, but with different expression pattern. CEACAM5 expression mainly with membranous staining is restricted on the superficial epithelium. However, OPN expression with mainly cytoplasmic staining is restricted on the deep epithelium. No colocalization of CEACAM5 and OPN have been observed in normal tissue of tongue. In squamous carcinoma of tongue, CEACAM5 expression with cytoplasmic staining is different from normal tongue tissue with membranous staining, and the transformation of CEACAM5 distribution from membrane to cytoplasm is an important incident for the invasion and differentiation of tumor. CEACAM5 and OPN are colocalized in cytoplasm, and a significant correlation was observed between the positive colocalization and the negative colocalization in the depth of invasion and the differentiation of the tumor.

FLJ10540 is associated with tumor progression in nasopharyngeal carcinomas and contributes to nasopharyngeal cell proliferation, and metastasis via osteopontin/CD44 pathway

Background

Nasopharyngeal carcinoma (NPC) is well-known for its highly metastatic characteristics, but little is known of its molecular mechanisms. New biomarkers that predict clinical outcome, in particular the ability of the primary tumor to develop metastatic tumors are urgently needed. The aim of this study is to investigate the role of FLJ10540 in human NPC development.

Methods

A bioinformatics approach was used to explore the potentially important regulatory genes involved in the growth/metastasis control of NPC. FLJ10540 was chosen for this study. Two co-expression strategies from NPC microarray were employed to identify the relationship between FLJ10540 and osteopontin. Quantitative-RT-PCR, immunoblotting, and immunohistochemistry analysis were used to investigate the mRNA and protein expression profiles of FLJ10540 and osteopontin in the normal and NPC tissues to confirm microarray results. TW01 and Hone1 NPC cells with overexpression FLJ10540 or siRNA to repress endogenous FLJ10540 were generated by stable transfection to further elucidate the molecular mechanisms of FLJ10540-elicited cell growth and metastasis under osteopontin stimulation.

Results

We found that osteopontin expression exhibited a positive correlation with FLJ10540 in NPC microarray. We also demonstrated comprehensively that FLJ10540 and osteopontin were not only overexpressed in NPC specimens, but also significantly correlated with advanced tumor and lymph node-metastasis stages, and had a poor 5-year survival rate, respectively. Stimulation of NPC parental cells with osteopontin results in an increase in FLJ10540 mRNA and protein expressions. Functionally, FLJ10540 transfectant alone, or stimulated with osteopontin, exhibited fast growth and increased metastasis as compared to vehicle control with or without osteopontin stimulation. Conversely, knockdown of FLJ10540 by siRNA results in the suppression of NPC cell growth and motility. Treatment with anti-CD44 antibodies in NPC parental cells not only resulted in a decrease of FLJ10540 protein, but also affected the abilities of FLJ10540-elicited cell growth and motility in osteopontin stimulated-NPC cells.

Conclusions

These findings suggest that FLJ10540 may be critical regulator of disease progression in NPC, and the underlying mechanism may involve in the osteopontin/CD44 pathway.

Osteopontin induces growth of metastatic tumors in a preclinical model of non-small lung cancer

Osteopontin (OPN), also known as SPP1 (secreted phosphoprotein), is an integrin binding glyco-phosphoprotein produced by a variety of tissues. In cancer patients expression of OPN has been associated with poor prognosis in several tumor types including breast, lung, and colorectal cancers. Despite wide expression in tumor cells and stroma, there is limited evidence supporting role of OPN in tumor progression and metastasis. Using phage display technology we identified a high affinity anti-OPN monoclonal antibody (hereafter AOM1). The binding site for AOM1 was identified as SVVYGLRSKS sequence which is immediately adjacent to the RGD motif and also spans the thrombin cleavage site of the human OPN. AOM1 efficiently inhibited OPNa binding to recombinant integrin αvβ3 with an IC50 of 65 nM. Due to its unique binding site, AOM1 is capable of inhibiting OPN cleavage by thrombin which has been shown to produce an OPN fragment that is biologically more active than the full length OPN. Screening of human cell lines identified tumor cells with increased expression of OPN receptors (αvβ3 and CD44v6) such as mesothelioma, hepatocellular carcinoma, breast, and non-small cell lung adenocarcinoma (NSCLC). CD44v6 and αvβ3 were also found to be highly enriched in the monocyte, but not lymphocyte, subset of human peripheral blood mononuclear cells (hPBMCs). In vitro, OPNa induced migration of both tumor and hPBMCs in a transwell migration assay. AOM1 significantly blocked cell migration further validating its specificity for the ligand. OPN was found to be enriched in mouse plasma in a number of pre-clinical tumor model of non-small cell lung cancers. To assess the role of OPN in tumor growth and metastasis and to evaluate a potential therapeutic indication for AOM1, we employed a Kras^G12D-LSLp53^fl/fl subcutaneously implanted in vivo model of NSCLC which possesses a high capacity to metastasize into the lung. Our data indicated that treatment of tumor bearing mice with AOM1 as a single agent or in combination with Carboplatin significantly inhibited growth of large metastatic tumors in the lung further supporting a role for OPN in tumor metastasis and progression.

Osteopontin is overexpressed in colorectal carcinoma and is correlated with P53 by immunohistochemistry

Osteopontin (OPN), a secreted phosphorylated glycoprotein, has been found to be involved in carcinogenesis, progression and metastasis of several types of cancers. The aim of the present study was to investigate the immunohistochemical expression of OPN in colorectal carcinoma (CRC) and its relationship with clinicopathological parameters and P53. Expression of OPN, Ki-67 and TP53 was detected in 77 cases of CRC by immunohistochemistry and the correlation of the expression of OPN with clinicopathological features, Ki-67 and P53 staining was investigated. Thirty-eight cases (49.4%) of CRC demonstrated OPN overexpression. Overexpression of OPN was associated with lymph node metastasis (P=0.025) and Dukes' stages (P=0.031), but not with gender, histological differentiation, depth of tumor invasion, TNM stages or Ki-67 index. The correlation between expression of OPN and TP53 was statistically significant (P=0.030). In conclusion, OPN is overexpressed in CRC, and plays a role in tumor progression and metastasis, which is possibly regulated by P53.

Combination of haptoglobin and osteopontin could predict colorectal cancer hepatic metastasis

PURPOSE

This study aimed to identify novel molecular markers for the early detection of colorectal cancer liver metastasis.

METHODS

Genes related to hepatic metastasis were screened from the Oncomine database. The candidate markers were tested by immunohistochemistry, and their predictive accuracy was assessed by the cross-validation method and an independent test set.

RESULTS

We got three datasets containing 2,973 genes that were highly expressed in primary colon cancer tissues compared with non-metastatic colon cancer tissues and identified 7 candidate molecules for immunohistochemical validation. A total of 213 colorectal cancer samples were randomly divided into a training set (113 cases) and a blind testing set (100 cases). In the training set, immunohistochemical analysis showed that HP, OPN, and PTGIS expression were significantly higher in the hepatic metastasis group than in the non-metastasis group. Logistic regression analysis showed that HP and OPN levels in primary tumors and lymph node metastasis status were the only significant (P<0.05) parameters for detecting liver metastasis. The predictive accuracy of markers was assessed by the cross-validation method and an independent test set. In leave-one-out cross-validation, the two markers combined with clinicopathologic features resulted in 91.2% sensitivity and 96.4% specificity for hepatic metastasis detection. In an independent test set, the combination achieved 94.5% sensitivity and 88.9% specificity for predicting the hepatic metastasis of colorectal cancer.

CONCLUSIONS

Our results suggest that combined HP and OPN expression levels are significantly related to liver metastasis and prognosis, and, if this is validated, they could be used as accurate predictors of liver metastasis in colorectal cancer.

Nuclear localization of 14-3-3epsilon inversely correlates with poor long-term survival of patients with colorectal cancer

BACKGROUND

14-3-3ε regulates diverse biological processes and plays a significant role in the formation of malignant tumors. However, the localization and clinical significance of 14-3-3ε in colorectal cancer (CRC) have not been elucidated.

METHODS

We investigated 14-3-3ε expression and its prognostic significance in CRC. CRC surgical samples were taken from 137 clinicopathologically characterized CRC cases. 14-3-3ε expression was tested by immunohistochemical assay. Separate Western blot of nuclear and cytosol preparations confirmed nuclear localization of 14-3-3ε protein.

RESULTS

Nuclear expression of 14-3-3ε was observed in 76.9% of normal colorectal tissue and 78.8% of all CRC samples. Statistical analysis showed that there was significant difference of nuclear 14-3-3ε expression in patients categorized according to lymph node metastasis. A trend was identified between decreasing nuclear 14-3-3ε expression in CRC and worsening clinical prognosis. Multivariate analysis showed that loss of nuclear 14-3-3ε expression was an independent prognostic indicator for patient's survival.

CONCLUSIONS

The current data provide evidence that 14-3-3ε is not exclusively a cytosolic protein, but is also detectable within the nucleus. Our results suggest that nuclear 14-3-3ε as a suppressor may serve as important biomarker of tumor metastasis. Loss of nuclear 14-3-3ε is closely associated with poor overall survival in CRC patients.

Host-derived osteopontin maintains an acute inflammatory response to suppress early progression of extrinsic cancer cells

The matricellular protein osteopontin (OPN), expressed in various cancer types and elevated in the blood of cancer patients, is thought to have different functions when derived from host versus cancer cells. To assess the effect of host-derived OPN on growth of cancers of epithelial origin, we established a line of cutaneous squamous cell carcinoma (SCC) cells, named ONSC, which lacks the OPN gene and develops SCC in syngeneic wild-type (WT) and OPN-null mice. At 8 and/or 10 week after subcutaneous injection of ONSC cells in mice, however, there was a lower tumor incidence in WT mice, suggesting that host-derived OPN is associated with suppression of early growth of extrinsic cancer cells. Histological, immunohistochemical, biochemical and hematological analyses were performed on the tumor microenvironment and blood from tumor-bearing mice during the first week after implantation. Host-derived OPN suppression of extrinsic ONSC cell progression is likely mediated through elicitation of an early innate inflammatory response, through its function as a chemoattractant and/or by enhancing survival of inflammatory cells. Further, consistent with a previous report, the serum levels of host-derived OPN, which are elevated during the early phase of tumor growth in mice implanted with ONSC, appear to reflect an anti-tumor progression effect.

Prognosis of ampullary cancer based on immunohistochemical type and expression of osteopontin

Background

Ampullary cancer (AC) was classified as pancreatobiliary, intestinal, or other subtype based on the expression of cytokeratin 7 (CK7) and cytokeratin 20 (CK20). We aimed to explore the association of AC subtype with patient prognosis.

Methods

The relationship of AC subtype and expression of Osteopontin (OPN) with the prognosis of 120 AC patients after pancreaticoduodenectomy was investigated.

Results

The patients had pancreatobiliary (CK7⁺/CK20^-, n = 24, 20%), intestinal (CK7^-/CK20⁺, n = 29, 24.2%) or other (CK7⁺/CK20⁺ or CK7^-/CK20^-, n = 67, 55.8%) subtypes of AC, and their median survival times were 23 ± 4.2, 38 ± 2.8 and 64 ± 16.8 months, respectively. The survival times of 64 OPN^- patients (53.3%) and 56 OPN⁺ patients (46.7%) were 69 ± 18.4 and 36 ± 1.3 months, respectively. There was no significant effect of AC subtype on survival of OPN^- patients. For OPN⁺ patients, those with pancreatobiliary AC had a shorter survival time (22 ± 6.6 months) than those with intestinal AC (37 ± 1.4 months, p = 0.041), and other AC subtype (36 ± 0.9 months, p = 0.010); intestinal and other AC subtypes had similar survival times.

Conclusions

The prognosis of AC patients can be estimated based on immunohistochemical classification and OPN status.

Osteopontin and endostatin concentrations in peripheral blood of patients with adrenal tumors undergoing unilateral adrenalectomy

Peripheral blood osteopontin (OPN) and endostatin (END) levels were studied in 35 patients with adrenal cortex tumors and 10 patients with pheochromocytoma before unilateral adrenalectomy, as well as in 10 healthy subjects (controls). Thirty days after surgery, OPN and END were evaluated again in 16 patients with adrenal cortex tumors and 4 female patients with pheochromocytoma. Before surgery, OPN blood concentrations increased in the group of patients with adrenal cortex carcinomas as compared to controls (p < 0.001) and the group with Conn syndrome (p < 0.05); they did not change after surgery. Before adrenalectomy, OPN blood levels in pheochromocytoma patients were also lower than in Conn syndrome subjects (p < 0.05). After adrenalectomy, the normal concentrations of END decreased only in the group of patients with hormonally inactive cortical adenomas (p < 0.05). We were unable to demonstrate any relationships between removed tumor volumes and OPN or END blood levels.

Prognostic significance of osteopontin in hepatocellular carcinoma: a meta-analysis

Osteopontin (OPN) has been implicated in tumor development and progression for several years. However, the prognostic value of OPN overexpression in patients with hepatocellular carcinoma (HCC) remains controversial. We performed a meta-analysis to assess the relationship between OPN overexpression and clinical outcome of HCC. A meta-analysis of seven studies (1,158 patients) was carried out to evaluate the association between OPN and overall survival (OS) and disease-free survival (DFS) in HCC patients. The correlation between OPN and tumor vascular invasion or other invasion-related parameters was also assessed. Data were synthesized with random effect model of DerSimonian and Laird, hazard ratio (HR) or odds ratio (OR) with its 95% confidence interval (CI) was used as the effect size estimate. Our analysis results indicated that high OPN expression predicted poor OS (HR: 1.37, 95% CI: 1.21-1.55) and DFS (HR: 1.62, 95% CI: 1.24-2.11) of HCC. OPN overexpression tended to be associated with the presence of tumor vascular invasion (OR: 1.93, 95% CI: 0.97-3.84) and advanced tumor grade (OR: 1.74, 95% CI: 0.95-3.18). By this study, we conclude that OPN overexpression indicates a poor prognosis for patients with HCC, it may also have predictive potential for HCC invasion and metastasis.

Wnt-β-catenin-Tcf-4 signalling-modulated invasiveness is dependent on osteopontin expression in breast cancer

Background:

We have previously demonstrated that Tcf-4 regulates osteopontin (OPN) in rat breast epithelial cells, Rama37. In this report, we have examined the importance of this regulation in human breast cancer.

Methods:

The regulatory roles of Tcf-4 on cell invasion and OPN expression were investigated. The mRNA expression of Tcf-4 and OPN, and survival of breast cancer patients were correlated.

Results:

Tcf-4 enhanced cell invasion in both MCF10AT and MDA MB 231 breast cancer cells by transcriptionally activating OPN expression. Osteopontin was activated by Wnt signalling in MDA MB 231 cells. Paradoxical results on Tcf-4-regulated OPN expression in MCF10AT (activation) and Rama37 (repression) cells were shown to be a result of differential Wnt signalling competency in MCF10AT and Rama37 cells. High levels of OPN and Tcf-4 mRNA expression were significantly associated with survival in breast cancer patients. Most importantly, Tcf-4-positive patients had a poorer prognosis when OPN was overexpressed, while OPN-negative patients had a better prognosis when Tcf-4 was overexpressed.

Conclusion:

Our results suggest that Tcf-4 can act as a repressor or activator of breast cancer progression by regulating OPN expression in a Wnt-dependent manner and that Tcf-4 and OPN together may be a novel prognostic indicator for breast cancer progression.

Elevated content of osteopontin in plasma and tumor tissues of patients with laryngeal and hypopharyngeal carcinoma associated with metastasis and prognosis

The aim of this study was to evaluate the usefulness of osteopontin (OPN) expression level in plasma and tumor tissues of patients with laryngeal and hypopharyngeal squamous-cell carcinoma for predicting metastasis and survival of this tumor. The OPN expression in tumor tissues was detected by immunohistochemical staining in a tissue microarray of laryngeal and hypopharyngeal carcinomas, and the OPN level in plasma was measured by ELISA. The expression levels of OPN in plasma and tumor tissues were associated with clinicopathological features and survival of laryngeal and hypopharyngeal carcinomas. Results showed that the OPN expression quantitation either in tissues or plasma was significantly correlated with differentiation and lymphatic metastasis of the laryngeal and hypopharyngeal carcinoma. Elevated OPN level of plasma and tissues was significantly associated with poor survival. In conclusion, elevated OPN level in plasma and tumor tissues was significantly associated with metastasis and survival of laryngeal and hypopharyngeal carcinomas. Elevated OPN level in plasma and tumor tissues may become a useful indicator of prognosis for laryngeal and hypopharyngeal cancers.

Correlation between osteopontin messenger RNA expression and microcalcification shown on sonography in papillary thyroid carcinoma

OBJECTIVES

The aims of this study were to investigate the correlation between osteopontin expression and microcalcification seen on sonograms of human papillary thyroid carcinoma and to explore the mechanism of microcalcification in these tumors.

METHODS

Real-time reverse transcription-polymerase chain reaction and immunohistochemistry were used to determine expression levels and locations of osteopontin in 56 pathologically verified papillary thyroid carcinoma nodules. Osteopontin expression correlated with microcalcification and other sonographic signs recorded preoperatively.

RESULTS

Osteopontin expression in the papillary thyroid carcinoma group was significantly enhanced compared with the control group for both messenger RNA and protein levels (P < .05). Osteopontin expression was significantly related to microcalcification and lymph node metastasis (P < .05), as shown on sonography.

CONCLUSIONS

Our results suggest a possible role for osteopontin in the formation of microcalcification in papillary thyroid carcinoma; the sonographic signs can reflect the pathologic and biological behavior of these tumors.

Pre- and post-translational regulation of osteopontin in cancer

Osteopontin (OPN) is a matricellular protein that binds to a number of cell surface receptors including integrins and CD44. It is expressed in many tissues and secreted into body fluids including blood, milk and urine. OPN plays important physiological roles in bone remodeling, immune response and inflammation. It is also a tumour-associated protein, and elevated OPN levels are associated with tumour formation, progression and metastasis. Research has revealed a promising role for OPN as a cancer biomarker. OPN is subject to alternative splicing, as well as post-translational modifications such as phosphorylation, glycosylation and proteolytic cleavage. Functional differences have been revealed for different isoforms and post-translational modifications. The pattern of isoform expression and post-translational modification is cell-type specific and may influence the potential role of OPN in malignancy and as a cancer biomarker.

Spotlight on differentially expressed genes in urinary bladder cancer

INTRODUCTION

We previously identified common differentially expressed (DE) genes in bladder cancer (BC). In the present study we analyzed in depth, the expression of several groups of these DE genes.

MATERIALS AND METHODS

Samples from 30 human BCs and their adjacent normal tissues were analyzed by whole genome cDNA microarrays, qRT-PCR and Western blotting. Our attention was focused on cell-cycle control and DNA damage repair genes, genes related to apoptosis, signal transduction, angiogenesis, as well as cellular proliferation, invasion and metastasis. Four publicly available GEO Datasets were further analyzed, and the expression data of the genes of interest (GOIs) were compared to those of the present study. The relationship among the GOI was also investigated. GO and KEGG molecular pathway analysis was performed to identify possible enrichment of genes with specific biological themes.

RESULTS

Unsupervised cluster analysis of DNA microarray data revealed a clear distinction in BC vs. control samples and low vs. high grade tumors. Genes with at least 2-fold differential expression in BC vs. controls, as well as in non-muscle invasive vs. muscle invasive tumors and in low vs. high grade tumors, were identified and ranked. Specific attention was paid to the changes in osteopontin (OPN, SPP1) expression, due to its multiple biological functions. Similarly, genes exhibiting equal or low expression in BC vs. the controls were scored. Significant pair-wise correlations in gene expression were scored. GO analysis revealed the multi-facet character of the GOIs, since they participate in a variety of mechanisms, including cell proliferation, cell death, metabolism, cell shape, and cytoskeletal re-organization. KEGG analysis revealed that the most significant pathway was that of Bladder Cancer (p = 1.5×10(-31)).

CONCLUSIONS

The present work adds to the current knowledge on molecular signature identification of BC. Such works should progress in order to gain more insight into disease molecular mechanisms.

Soluble markers for diagnosis of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a highly aggressive and invasive tumor, whose incidence is expected to peak, in many countries, at the end of the present decade, 20–40 years after the peak of asbestos use (asbestos being the most important etiological factor). MPM has a poor prognosis, in part, owing to a difficult and often late diagnosis hindered by a lack of available tests able to diagnose or predict this cancer in its early stages. Recently, there has been increased interest in noninvasive, economic and well-accepted diagnostic tests for screening of asbestos-exposed subjects, as well as for monitoring response of MPM patients to treatment. Several markers have been studied in biofluids, such as serum, plasma and pleural effusions, especially using ELISA, and some of them are still under investigation. However, only mesothelin and ostepontin have proven levels of sensitivity and specificity that are worth testing in the clinical setting.

Identification of early molecular markers for breast cancer

Background

The ductal carcinoma in situ (DCIS) of the mammary gland represents an early, pre-invasive stage in the development of invasive breast carcinoma. Since DCIS is a curable disease, it would be highly desirable to identify molecular markers that allow early detection. Mice transgenic for the WAP-SV40 early genome region were used as a model for DCIS development. Gene expression profiling was carried out on DCIS-bearing mice and control animals. Additionally, a set of human DCIS and invasive mammary tumors were analyzed in a similar fashion. Enhanced expression of these marker genes in human and murine samples was validated by quantitative RT-PCR. Besides, marker gene expression was also validated by immunohistochemistry of human samples. Furthermore in silico analyses using an online microarray database were performed.

Results

In DCIS-mice seven genes were identified that were significantly up-regulated in DCIS: DEPDC1, NUSAP1, EXO1, RRM2, FOXM1, MUC1 and SPP1. A similar up-regulation of homologues of the murine genes was observed in human DCIS samples. Enhanced expression of these genes in DCIS and IDC (invasive ductal carcinoma) was validated by quantitative RT-PCR and immunohistochemistry.

Conclusions

By comparing murine markers for the ductal carcinoma in situ (DCIS) of the mammary gland with genes up-regulated in human DCIS-samples we were able to identify a set of genes which might allow early detection of DCIS and invasive carcinomas in the future. The similarities between gene expression in DCIS and invasive carcinomas in our data suggest that the early detection and treatment of DCIS is of utmost relevance for the survival of patients who are at high risk of developing breast carcinomas.

Osteopontin-c splicing isoform contributes to ovarian cancer progression

Ovarian carcinoma is one of the most aggressive gynecological diseases and generally diagnosed at advanced stages. Osteopontin (OPN) is one of the proteins overexpressed in ovarian cancer and is involved in tumorigenesis and metastasis. Alternative splicing of OPN leads to 3 isoforms, OPNa, OPNb, and OPNc. However, the expression pattern and the roles of each of these isoforms have not been previously characterized in ovarian cancer. Herein, we have evaluated the expression profiling of OPN isoforms in ovarian tumor and nontumor samples and their putative roles in ovarian cancer biology using in vitro and in vivo functional assays. OPNa and OPNb were expressed both in tumor and nontumor ovarian samples, whereas OPNc was specifically expressed in ovarian tumor samples. The isoform OPNc significantly activated OvCar-3 cell proliferation, migration, invasion, anchorage-independent growth and tumor formation in vivo. Additionally, we have also shown that some of the OPNc-dependent protumorigenic roles are mediated by PI3K/Akt signaling pathway. OPNc stimulated immortalized ovarian epithelial IOSE cell proliferation, indicating a role for this isoform in ovarian cancer tumorigenesis. Functional assays using OPNc conditioned medium and an anti-OPNc antibody have shown that most cellular effects observed herein were promoted by the secreted OPNc. According to our data, OPNc-specific expression in ovarian tumor samples and its role on favoring different aspects of ovarian cancer progression suggest that secreted OPNc contributes to the physiopathology of ovarian cancer progression and tumorigenesis. Altogether, the data open possibilities of new therapeutic approaches for ovarian cancer that selectively down regulate OPNc, altering its properties favoring ovarian tumor progression.

Osteopontin promotes CCL5-mesenchymal stromal cell-mediated breast cancer metastasis

The interaction between cancer and its local microenvironment can determine properties of growth and metastasis. A critical component of the tumor microenvironment in this context is the cancer-associated fibroblast (CAF), which can promote tumor growth, angiogenesis and metastasis. It has been hypothesized that CAF may be derived from mesenchymal stromal cells (MSC), derived from local or distant sources. However, the signaling mechanisms by which tumors and MSCs interact to promote CAF-dependent cancer growth are largely unknown. In this study with in vitro and in vivo models using MDA-MB231 human breast cancer cells, we demonstrate that tumor-derived osteopontin (OPN) induces MSC production of CCL5; the mechanism involves OPN binding to integrin cell surface receptors and activator protein-1 c-jun homodimer transactivation. In a murine xenograft model, concomitant inoculation of MSC with MDA-MB231 cells induces: (i) significantly increased growth and metastasis of MB231 cells and (ii) increased MSC migration to metastatic sites in lung and liver; this mechanism is both OPN and CCL5 dependent. MSCs retrieved from sites of metastases exhibit OPN-dependent expression of the CAF markers, α-smooth muscle actin, tenascin-c, CXCL12 (or stromal cell-derived factor 1) and fibroblast-specific protein-1 and the matrix metalloproteinases (MMP)-2 and MMP-9. Based upon these results, we propose that tumor-derived OPN promotes tumor progression via the transformation of MSC into CAF.

Osteopontin as a potential biomarker of proliferation and invasiveness for lung cancer

PURPOSE

Lung cancer is one of the most malignant tumors and poses a significant threat to human health. Osteopontin (OPN) is a variably expressed, secreted glycophosphoprotein that mediates the growth and metastases of several carcinoma types. In this study, we aimed to understand the role of OPN in lung cancer cell proliferation and invasiveness.

METHODS

Expression of OPN was examined using an immunohistochemical method in paraffin-embedded sections collected from 49 patients with lung cancer. We silenced OPN expression by lentivirus-mediated OPN-specific small interfering RNA (siRNA) and examined the proliferation and invasiveness of OPN-silenced lung cancer cell (A549) through MTT, BrdU, flow cytometry, and Matrigel assay. In addition, we tested the role of individual OPN splice variants in A549 cell growth and invasion by constructing OPN overexpression lentiviruses.

RESULT

Downregulation of OPN inhibited A549 cell proliferation and in vivo tumor growth, abrogated augmentation of invasion, induced G1-phase cell cycle arrest, and induced cell late apoptosis and necrosis. Moreover, the proliferation and invasiveness was linked to different OPN splice variants, of which OPN-b affected the cell proliferation and OPN-c showed significant correlation with invasion behavior.

CONCLUSIONS

Our data suggested that OPN served as a potential biomarker for invasive lung cancer and provided new molecular-targeted therapy for lung cancer based on lentivirus-mediated RNA interference.

Transcription factor c-Myb promotes the invasion of hepatocellular carcinoma cells via increasing osteopontin expression

Background

Specific gene expression is tightly regulated by various transcription factors. Osteopontin (OPN) is a phosphoprotein that mediates hepatocellular carcinoma (HCC) progression and metastasis. However, the mechanism of OPN up-regulation in HCC metastasis remains to be clarified.

Methods

Oligonucleotide array-based transcription factor assays were applied to compare different activities of transcription factors in two human HCC cell lines with different OPN expression levels. The effects of one selected transcription factor on OPN expression were further evaluated.

Results

Eleven transcription factors were over-expressed in metastatic HCC cell line HCCLM6 cells whereas twelve transcription factors were down-regulated. Electrophoretic mobility shift assays (EMSA) and reporter gene assays showed that one of up-regulated transcription factors c-Myb could bind the OPN promoter and increase its transcription activity. In addition, small interfering RNA targeting c-Myb could inhibit OPN expression and significantly decrease migration and invasion of HCCLM6 cells in vitro.

Conclusion

Our data first demonstrate that c-Myb has a functionally important role in the regulation of OPN expression in HCC cells, suggesting that c-Myb might be a new target to control HCC metastasis.

Osteopontin expression correlates with nuclear factor-κB activation and apoptosis downregulation in clear cell renal cell carcinoma

Osteopontin (OPN) is a phosphoglycoprotein implicated in tumorigenesis and tumor cell metastasis. Apoptosis inhibition is one of the mechanisms that contribute to development and progression of cancer, and might be initiated by OPN interaction with tumor cells. The aim of this study was to analyze the relation between OPN and nuclear factor-kappa B (NF-κB) expression in clear cell renal cell carcinoma (CCRCC), as well as their relation to apoptotic activity of tumor cells. Expression of OPN protein and p65 NF-κB subunit was analyzed immunohistochemically in 87 CCRCC samples, and compared mutually and with apoptotic index. Expression of OPN mRNA was analyzed using quantitative real-time PCR and compared with OPN and NF-κB protein expression in 22 CCRCC samples. Statistical analysis showed an association of p65 NF-κB with OPN mRNA (p=0.015) and protein (p<0.001). Also, we found an inverse relationship of OPN with NF-κB protein expression and apoptotic activity of tumor cells (p=0.006 and p=0.022, respectively). Our results indicate that p65 NF-κB signaling pathway may be involved in OPN-mediated CCRCC progression, partly by protecting tumor cells from apoptosis. Therefore, both molecules can constitute potential targets for therapeutic intervention in CCRCC.

Osteopontin promotes hepatocellular carcinoma invasion by up-regulating MMP-2 and uPA expression

Osteopontin (OPN) is over-expressed in a variety of cancers, but its role in hepatocellular carcinoma (HCC) progression has not been clarified. In this study, weakly tumorigenic, non-metastastic human HCC cell line SMMC-7721 cells were forced to over-express OPN via stable transfection. A series of functional assays were performed to assess the effects of OPN on tumor cell behaviors and cDNA microarray was used to identify the genes regulated by OPN. The results showed that OPN significantly enhanced the migration and invasion of SMMC-7721 cells in vitro. In addition, CD44v6 antibody could significantly inhibit the invasion of OPN over-expressing SMMC-7721 cells. Moreover, MMP-2 and uPA expressions were significantly up-regulated in OPN over-expressing SMMC-7721 cells. Together, these findings indicate that OPN enhanced HCC cells invasion through interaction with its receptor CD44v6 and increased MMP-2 and uPA expressions, providing at least one mechanism for OPN-mediated HCC progression and metastasis.

Global downstream pathway analysis reveals a dependence of oncogenic NF-E2-related factor 2 mutation on the mTOR growth signaling pathway

In multicellular organisms, adaptive responses to oxidative stress are regulated by NF-E2-related factor 2 (NRF2), a master transcription factor of antioxidant genes and phase II detoxifying enzymes. Aberrant activation of NRF2 by either loss-of-function mutations in the Keap1 gene or gain-of-function mutations in the Nrf2 gene occurs in a wide range of human cancers, but details of the biological consequences of NRF2 activation in the cancer cells remain unclear. Here, we report that mutant NRF2 induces epithelial cell proliferation, anchorage-independent growth, and tumorigenicity and metastasis in vivo. Genome-wide gene expression profiling revealed that mutant NRF2 affects diverse molecular pathways including the mammalian target of rapamycin (mTOR) pathway. Mutant NRF2 upregulates RagD, a small G-protein activator of the mTOR pathway, which was also overexpressed in primary lung cancer. Consistently, Nrf2-mutated lung cancer cells were sensitive to mTOR pathway inhibitors (rapamycin and NVP-BEZ235) in both in vitro and an in vivo xenograft model. The gene expression signature associated with mutant NRF2 was a marker of poor prognosis in patients with carcinoma of the head and neck region and lung. These results show that oncogenic Nrf2 mutation induces dependence on the mTOR pathway during carcinogenesis. Our findings offer a rationale to target NRF2 as an anticancer strategy, and they suggest NRF2 activation as a novel biomarker for personalized molecular therapies or prognostic assessment.

Plasma decorin predicts the presence of esophageal squamous cell carcinoma

Using a microarray technique, we found decorin to be underexpressed, but osteopontin (OPN) to be overexpressed, in esophageal squamous cell carcinoma (ESCC). This study aims to examine whether plasma decorin and OPN plus personal substances use (tobacco, alcohol and areca) can serve as suitable clinical markers to predict the presence of ESCC. In total, 570 archived plasma specimens (275 patients and 295 controls) were collected from 2 medical centers in Taiwan between 2000 and 2008. Decorin and OPN protein levels were measured by ELISA. Means and standard deviation of plasma decorin were 5.6 + or - 3.6 ng/ml in case patients, which were significantly lower than those in controls (7.8 + or - 3.1, p < 0.0001). Plasma OPN levels in case patients were not significantly different from controls (p = 0.33). When compared to subjects with the lowest quartile of plasma decorin, those with the highest quartile one had a significantly lower risk to have ESCC (Adjusted OR = 0.03, p < 0.001). Receiver operator characteristic (ROC) analysis was performed for the combination of plasma decorin and 3 substances use (smoke, alcohol and areca) for the patients compared with the controls. The area under the curve was 88.6% and the optimal cut-point of ROC curve (any 3 factors) had 73.5% sensitivity and 90.2% specificity with approximately 82% of corrected classification. Plasma decorin, but not OPN, is a potential clinical marker for the detection of ESCC. When plasma decorin plus the use of the 3 substances are combined, this factor cluster could be used to detect the presence of ESCC.

Osteopontin is a new target molecule for ovarian clear cell carcinoma therapy

Recent studies have demonstrated overexpression of osteopontin (OPN) in ovarian clear cell carcinoma. Here, we revealed the role of OPN in invasiveness in ovarian clear cell carcinoma. We used immunofluorescence analysis to detect OPN in a total of 160 patient-derived specimens. Ovarian clear cell carcinoma cell lines, RMG-1 and TOV-21G, were used to monitor changes in OPN and integrin levels, and cell invasiveness following treatment with OPN, simvastatin, and transfection with siRNA. Immunofluorescence analysis revealed statistically significant differences among the histological groups, and ovarian clear cell carcinoma expressed a strong OPN signal. The OPN receptors, alpha v and 5, and beta 1 and 3 integrins, were increased after treatment with OPN. Invasion assays indicated that OPN enhanced in vitro extracellular matrix invasion dose-dependently in ovarian clear cell carcinoma. Simvastatin significantly reduced expression of OPN and the integrins, and decreased ECM invasion. RNA interference also suppressed ECM invasion. These results suggest that down- or up-regulation of OPN is involved in carcinoma cell invasion. We thus conclude that OPN regulation could have a crucial role in ovarian clear cell carcinoma therapy.

Osteopontin, a single marker for predicting the prognosis of patients with tumor-node-metastasis stage I hepatocellular carcinoma after surgical resection

BACKGROUND AND AIM

Osteopontin (OPN) has been linked to clinical outcomes in several solid tumors. However, it has not been fully evaluated whether OPN could be used as a single marker for the prognosis of patients with hepatocellular carcinoma (HCC), particularly in patients of the tumor-node-metastasis (TNM) stage I.

METHODS

A total of 151 patients with HCC who underwent surgical resection were enrolled, including 112 patients of the TNM stage I. OPN expression was evaluated using immunohistochemistry in the tissue microarrays derived from these patients. Immunoreactivity was classified according to the percentage and intensity of staining: negative (-), weak (+) and strong (++). The impact of OPN expression on survival of patients was analyzed.

RESULTS

In total, 65.6% (99 of 151) of HCC tissues expressed OPN. Overall survival in patients of OPN (-) group was significantly higher than those of OPN (+) or OPN (++) group (P = 0.049 and P = 0.001). Interestingly, in patients of the TNM stage I, OPN expression was correlated with the early recurrence after surgical resection (P = 0.001). Multivariate analysis showed that OPN expression was an independent prognostic factor for overall survival and disease-free survival in patients with the TNM stage I HCC (hazard ratio, 2.272, P = 0.014 and 1.982, P = 0.037).

CONCLUSIONS

These results suggest that OPN is commonly expressed in HCC and is a useful marker for predicting the prognosis of patients with the TNM stage I HCC, contributing to determining which individual patient needs adjuvant therapy to prevent the early recurrence after surgical resection.

Role of the metastasis-promoting protein osteopontin in the tumour microenvironment

Osteopontin (OPN) is a secreted protein present in bodily fluids and tissues. It is subject to multiple post-translational modifications, including phosphorylation, glycosylation, proteolytic cleavage and crosslinking by transglutamination. Binding of OPN to integrin and CD44 receptors regulates signalling cascades that affect processes such as adhesion, migration, invasion, chemotaxis and cell survival. A variety of cells and tissues express OPN, including bone, vasculature, kidney, inflammatory cells and numerous secretory epithelia. Normal physiological roles include regulation of immune functions, vascular remodelling, wound repair and developmental processes. OPN also is expressed in many cancers, and elevated levels in patients’ tumour tissue and blood are associated with poor prognosis. Tumour growth is regulated by interactions between tumour cells and their tissue microenvironment. Within a tumour mass, OPN can be expressed by both tumour cells and cellular components of the tumour microenvironment, and both tumour and normal cells may have receptors able to bind to OPN. OPN can also be found as a component of the extracellular matrix. The functional roles of OPN in a tumour are thus complex, with OPN secreted by both tumour cells and cells in the tumour microenvironment, both of which can in turn respond to OPN. Much remains to be learned about the cross-talk between normal and tumour cells within a tumour, and the role of multiple forms of OPN in these interactions. Understanding OPN-mediated interactions within a tumour will be important for the development of therapeutic strategies to target OPN.