Identification of osteopontin as the most consistently over-expressed gene in intrahepatic cholangiocarcinoma: Detection by oligonucleotide microarray and real-time PCR analysis

An Immunohistochemical Analysis of Osteopontin and S100 Calcium-binding Protein P is Useful for Subclassifying Large- and Small-duct Type Intrahepatic Cholangiocarcinomas

Intrahepatic cholangiocarcinoma (iCCA) has been newly subclassified into two different subtypes: large-duct (LD) type and small-duct (SD) type. However, many cases are difficult to subclassify, and there is no consensus regarding subclassification criteria. LD type expresses the highly sensitive diagnostic marker S100 calcium-binding protein P (S100P), while SD type lacks sensitive markers. We identified osteopontin (OPN) as a highly sensitive marker for SD type. This study aimed to develop new subclassification criteria for LD-type and SD-type iCCA. We retrospectively investigated 74 patients with iCCA and subclassified them based on whole-section immunostaining of S100P and OPN. Of the 74 cases, 41 were subclassified as LD type, 32 as SD type, and one was indeterminate. Notably, all S100P-negative cases had OPN positivity. Seventy-three of the 74 cases (98.6%) were clearly and easily subclassified as LD or SD type using only these 2 markers. We also determined the value of immunohistochemistry in cases that were difficult to diagnose based on hematoxylin-eosin and Alcian blue-periodic acid-Schiff staining. Furthermore, we analyzed the clinicopathological characteristics and prognoses of these 2 subtypes. LD type was a poor prognostic factor on univariate analysis; it had significantly worse overall survival ( P = 0.007) and recurrence-free survival ( P < 0.001) than the SD type. In conclusion, we propose new subclassification criteria for iCCA based on immunostaining of S100P and OPN. These criteria may help pathologists to diagnose subtypes of iCCA, supporting future clinical trials and the development of medications for these 2 subtypes as distinct cancers.

Osteopontin Takes Center Stage in Chronic Liver Disease

Osteopontin (OPN) was first identified in 1986. The prefix osteo- means bone; however, OPN is expressed in other tissues, including liver. The suffix -pontin means bridge and denotes the role of OPN as a link protein within the extracellular matrix. While OPN has well-established physiological roles, multiple "omics" analyses suggest that it is also involved in chronic liver disease. In this review, we provide a summary of the OPN gene and protein structure and regulation. We outline the current knowledge on how OPN is involved in hepatic steatosis in the context of alcoholic liver disease and non-alcoholic fatty liver disease. We describe the mechanisms whereby OPN participates in inflammation and liver fibrosis and discuss current research on its role in hepatocellular carcinoma and cholangiopathies. To conclude, we highlight important points to consider when doing research on OPN and provide direction for making progress on how OPN contributes to chronic liver disease.

Subclassification and Detection of New Markers for the Discrimination of Primary Liver Tumors by Gene Expression Analysis Using Oligonucleotide Arrays

Background/Aims

The failure to correctly differentiate between intrahepatic cholangiocarcinoma (CC) and hepatocellular carcinoma (HCC) is a significant clinical problem, particularly in terms of the different treatment goals for both cancers. In this study a specific gene expression profile to discriminate these two subgroups of liver cancer was established and potential diagnostic markers for clinical use were analyzed.

Methods

To evaluate the gene expression profiles of HCC and intrahepatic CC, Oligonucleotide arrays (AffymetrixU133A) were used. Overexpressed genes were checked for their potential use as new markers for discrimination and their expression values were validated by reverse transcription polymerase chain reaction and immunohistochemistry analyses.

Results

695 genes/expressed sequence tags (ESTs) in HCC (245 up-/450 down-regulated) and 552 genes/ESTs in CC (221 up-/331 down-regulated) were significantly dysregulated (p＜0.05, fold change >2, ≥70%). Using a supervised learning method, and one-way analysis of variance a specific 270-gene expression profile that enabled rapid, reproducible differentiation between both tumors and nonmalignant liver tissues was established. A panel of 12 genes (e.g., HSP90β, ERG1, GPC3, TKT, ACLY, and NME1 for HCC; SPT2, T4S3, CNX43, TTD1, HBD01 for CC) were detected and partly described for the first time as potential discrimination markers.

Conclusions

A specific gene expression profile for discrimination of primary liver cancer was identified and potential marker genes with feasible clinical impact were described.

Cholangiocarcinoma‑associated genes identified by integrative analysis of gene expression data

Cholangiocarcinoma (CCA) is characterized by delayed diagnosis and poor survival rate. Research efforts have focused on novel diagnostic technologies for this type of cancer. Transcriptomic microarray technology is a useful research strategy for investigating the molecular properties of CCA. The objective of the present study was to identify candidate biomarkers with high potential for clinical application in CCA using a meta‑analysis‑based approach. Gene expression profiles of CCA were downloaded from the Gene Expression Omnibus database for integrated analysis. All differentially expressed genes (DEGs) were analyzed by Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. Protein‑protein interaction (PPI) networks were further constructed, hub proteins were identified and functional modules were extracted. Following integrated analysis of the seven eligible datasets (428 cases and 46 controls), a set of 1,080 DEGs was identified, including 710 upregulated and 370 downregulated genes. Functional enrichment analysis demonstrated that 'chromosome organization' was a significantly enriched GO term in the biological process category. 'DNA replication', 'influenza A', and 'lysosome' were the top three significantly enriched KEGG pathways. Furthermore, PPI network analysis indicated that the significant hub proteins were histone deacetylase 1, cullin‑associated NEDD8‑dissociated protein 1, ubiquitin D, early growth response protein 1 and glycogen synthase kinase 3β. The majority of these proteins are involved in CCA. These results provided a set of targets that may help researchers to clarify further the underlying mechanisms of CCA tumorigenesis.

Osteopontin promotes metastasis of intrahepatic cholangiocarcinoma through recruiting MAPK1 and mediating Ser675 phosphorylation of β-Catenin

The incidence and mortality of intrahepatic cholangiocarcinoma (ICC) are increasing worldwide in recent decades. Osteopontin (OPN) plays an important role in cancer metastasis, but its functional mechanism in ICC is not clear yet. In this study, we found that OPN level was elevated both in plasma and tumor tissues of ICC patients, which was closely related to a shorter overall survival (OS) and high probability of tumor relapse after curative resection. The gain- and loss-of-function studies determined that OPN could promote ICC growth and metastasis. OPN selectively interacted with β-Catenin and knockdown of β-Catenin abrogated the effects induced by OPN. OPN recruited MAPK1 and activated MEK-MAPK1 pathway to mediate the S675 phosphorylation of β-Catenin and nucleus accumulation, which induced the activation of Wnt signaling. Moreover, a significant correlation between OPN and β-Catenin was found in ICC tissues. OPN, β-Catenin, and their combination were independent prognostic indicator for ICC patients. In conclusion, OPN promotes ICC progression through recruiting MAPK1 and activating the Wnt/β-Catenin pathway and can serve as a novel prognostic marker and therapeutic target for ICC.

Elevated levels of circulating osteopontin are associated with a poor survival after resection of cholangiocarcinoma

BACKGROUND & AIMS

Cholangiocarcinoma (CCA) represents a primary hepatic malignancy with incidence and mortality rising globally. Surgical treatment has remained the only potentially curative treatment option, but it is still unclear which patients benefit most from extended liver surgery, highlighting the need for new pre-operative stratification strategies. Osteopontin is a secreted extracellular glyco-phosphoprotein that has been associated with inflammation, metabolic disorders and cancer. Here, we examined the potential of circulating osteopontin serum levels as a diagnostic or prognostic biomarker in patients with CCA undergoing extended liver surgery.

METHODS

Osteopontin expression levels were analysed in human and murine CCA tumour samples, using semi-quantitative reverse transcriptase PCR and immunohistochemistry. Osteopontin serum concentrations were measured by enzyme-linked immunosorbent assay in 107 patients with CCA undergoing elective tumour resection as well as 55 healthy controls. Results were correlated with clinical data.

RESULTS

Correlating with an upregulation in CCA tumour cells and the tumour stroma, serum levels of osteopontin were elevated in patients with cholangiocarcinoma compared to healthy controls and patients with primary sclerosing cholangitis. Importantly, pre- and postoperative elevations of osteopontin showed a striking association with poor postoperative survival.

CONCLUSIONS

Serum osteopontin concentrations represent a promising prognostic biomarker in patients resectable CCA which could help to guide preoperative treatment decisions and to identify patients that will particularly benefit from extended liver surgery. Lay summary: Extended liver surgery is the only potentially curative treatment for patients with cholangiocarcinoma (CCA/biliary cancer), but it is currently unclear which patients benefit most from surgery. Detecting serum levels of osteopontin - a specific secreted glycoprotein involved in multiple human diseases - in CCA patients might help to identify those patients that particularly benefit from tumour resection.

Clinicopathological Significance of Osteopontin in Cholangiocarcinoma Cases

Cholangiocarcinoma (CCA) is generally a rare primary liver tumor of the bile duct with extremely poor clinical outcomes due to late diagnosis. Osteopontin (OPN) is the most abundant expressed gene in intrahepatic CCA and its involvement in tumor aggressiveness suggests it could be a useful prognostic biomarker. However, the prognostic significance of OPN expression in CCA is still controversial. We therefore immunohistochemically studied OPN expression in 354 resected CCAs and correlated the results with patient clinicopathological parameters. OPN expression was separately scored according to the percentage of cancer cells or degree of stromal tissue staining and classified as low (score 0-1) and high (score 2-3). OPN expression in CCA cells was found in 177 out of 354 patients (56.5%), whereas stroma was positive in 185 out of 354 patients (52.3%). Univariate analysis with several of the aforementioned parameters revealed that stromal but not cancer cell OPN expression was significantly associated with tumor size, tumor direct invasion into normal liver parenchyma, regional lymph node metastasis and higher staging. The combination of cancer cell and stromal OPN expression demonstrated a positive trend for linkage with lymph node metastasis. Multivariate analysis identified gender, the presence of lymphatic permeation and lymph node metastasis, but not OPN expression, as independent prognostic factors. This study confirms the presence of stromal OPN expression in tumor aggressiveness but not survival in CCA patients.

Suppression of trophoblast cell surface antigen 2 enhances proliferation and migration in liver fluke-associated cholangiocarcinoma

BACKGROUND AND AIM

Trophoblast cell surface antigen 2 (TROP2) or tumor-associated calcium signal transducer 2 (TACSTD2) is a 36-kDa type I transmembrane glycoprotein and exerts dual functions as an oncogene and tumor suppressor in cancer cells. In this study, we investigated the expression and functions of TROP2 in liver fluke-associated cholangiocarcinoma (CCA).

MATERIAL AND METHODS

TROP2 expression in 85 CCA tissues was detected by using immunohistochemistry. The methylation status of TROP2 promoter was studied in 15 matched pairs of normal and CCA formalin fixed paraffin embedded (FFPE) tissues using the bisulfite genomic sequencing (BGS) method. The functions of TROP2 on cancer cell behavior were investigated using siRNA in CCA cell lines. Proliferation, migration and invasion assays were performed. A PCR array was used to evaluate the impact of TROP2 knockdown on the gene expression profiles.

RESULTS

TROP2 was highly expressed in all normal bile duct epithelia, but significantly down-regulated in CCA cells. Sixty percent of CCA revealed promoter hypermethylation compared to the corresponding adjacent normal tissues. TROP2 knockdown significantly enhanced the proliferation and migration in CCA cell lines, and altered the expressions of MARCK, EMP1 and FILIP1L.

CONCLUSION

We provide new evidence that TROP2 is epigenetically down-regulated and operates as a negative regulator of cell proliferation and migration in liver fluke-associated CCA.

Identification of SPHK1 as a therapeutic target and marker of poor prognosis in cholangiocarcinoma

Cholangiocarcinoma (CCA) is characterized by a uniquely aggressive behavior and lack of effective targeted therapies. After analyzing the gene expression profiles of seven paired intrahepatic CCA microarrays, a novel sphingosine kinase 1 (SPHK1)/sphingosine-1-phosphate (S1P) pathway and a novel target gene, SPHK1, were identified. We hypothesized that therapeutic targeting of this pathway can be used to kill intrahepatic cholangiocarcinoma (CCA) cells. High levels of SPHK1 protein expression, which was evaluated by immunohistochemical staining of samples from 96 patients with intrahepatic CCA, correlated with poor overall survival. The SPHK1 inhibitor SK1-I demonstrated potent antiproliferative activity in vitro and in vivo. SK1-I modulated the balance of ceramide-sphinogosine-S1P and induced CCA apoptosis. Furthermore, SK1-I combined with JTE013, an antagonist of the predominant S1P receptor S1PR2, inhibited the AKT and ERK signaling pathways in CCA cells. Our preclinical data suggest SPHK1/S1P pathway targeting may be an effective treatment option for patients with CCA.

Meta-analysis of gene expression profiles identifies differential biomarkers for hepatocellular carcinoma and cholangiocarcinoma

Hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) are the members of hepatobiliary diseases. Both types of cancer often exert high levels of similarity in terms of phenotypic characteristics, thus leading to difficulties in HCC and CCA differential diagnoses. In this study, a transcriptome meta-analysis was performed on HCC and CCA microarray data to identify differential transcriptome networks and potential biomarkers for HCC and CCA. Raw data from nine gene expression profiling datasets, consisting of 1,185 samples in total, were methodologically compiled and analyzed. To evaluate differentially expressed (DE) genes in HCC and CCA, the levels of gene expression were compared between cancer and its normal counterparts (i.e., HCC versus normal liver and CCA versus normal bile duct) using t test (P < 0.05) and k-fold validation. A total of 226 DE genes were specific to HCC, 249 DE genes specific to CCA, and 41 DE genes in both HCC and CCA. Gene ontology and pathway enrichment analyses revealed different patterns between functional transcriptome networks of HCC and CCA. Cell cycle and glycolysis/gluconeogenesis pathways were exclusively dysregulated in HCC whereas complement and coagulation cascades as well as glycine, serine, and threonine metabolism were prodominantly differentially expressed in CCA. Our meta-analysis revealed distinct dysregulation in transcriptome networks between HCC and CCA. Certain genes in these networks were discussed in the context of HCC and CCA transition, unique characteristics of HCC and CCA, and their potentials as HCC and CCA differential biomarkers.

Screening of potential biomarkers for cholangiocarcinoma by integrated analysis of microarray data sets

Cholangiocarcinoma (CCA) continues to harbor a difficult prognosis and it is difficult to diagnose in its early stages. The molecular mechanisms of CCA oncogenesis and progression are poorly understood. This study aimed to identify candidate biomarkers for CCA. Integrated analysis of microarray data sets was performed to identify differentially expressed genes (DEGs) between CCA and normal tissues. Gene Ontology enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were then performed to identify the functions of DEGs. Furthermore, the protein-protein interaction (PPI) network of DEGs was constructed. The expressions of DEGs were validated in human CCA tissues by qRT-PCR. A set of 712 DEGs were identified in CCA compared with normal tissues, including 306 upregulated and 406 downregulated DEGs. It can be shown from the KEGG pathway analysis that some pathways may have important roles in pathology of CCA, including peroxisome proliferator-activated receptor signaling pathway, bile secretion, cell cycle, fat digestion and absorption. PPI network indicated that the significant hub proteins were PKM, SPP1 and TPM1. The abnormally overexpression PKM, SPP1 and TPM1 were closely related to oncogenesis and progression of CCA. PKM, SPP1, TPM1, COL1A1 and COL1A2 may serve as candidate biomarkers for diagnosis and prognosis of CCA.

An Omics Perspective on Molecular Biomarkers for Diagnosis, Prognosis, and Therapeutics of Cholangiocarcinoma

Cholangiocarcinoma (CCA) is an aggressive biliary tract malignancy arising from the epithelial bile duct. The lack of early diagnostic biomarkers as well as therapeutic measures results in severe outcomes and poor prognosis. Thus, effective early diagnostic, prognostic, and therapeutic biomarkers are required to improve the prognosis and prolong survival rates in CCA patients. Recent advancement in omics technologies combined with the integrative experimental and clinical validations has provided an insight into the underlying mechanism of CCA initiation and progression as well as clues towards novel biomarkers. This work highlights the discovery and validation of molecular markers in CCA identified through omics approaches. The possible roles of these molecules in various cellular pathways, which render CCA carcinogenesis and progression, will also be discussed. This paper can serve as a reference point for further investigations to yield deeper understanding in the complex feature of this disease, potentially leading to better approaches for diagnosis, prognosis, and therapeutics.

Role of osteopontin in the regulation of human bladder cancer proliferation and migration in T24 cells

Osteopontin (OPN), a secreted acid glycoprotein with a variety of functions, promotes tumor proliferation, differentiation, invasion and metastasis. The aim of the current study was to investigate whether OPN may serve as a potential therapeutic target for human bladder cancer. RNA interference (RNAi) was performed to downregulate the expression of the OPN gene in T24 human bladder cancer cells. The mRNA and protein expression levels of OPN following RNAi were determined using reverse transcription‑quantitative polymerase chain reaction and western blot analysis, respectively. In addition, the cell cycle progression, apoptosis and proliferation were investigated using by flow cytometric analysis and MTT assay. The cell invasion ability was measured using a Matrigel transwell assay. The mRNA and protein expression levels of OPN were found to be significantly downregulated following RNAi. The proliferation and invasion of T24 cells were significantly inhibited in vitro. In conclusion, RNAi‑targeting OPN may inhibit the proliferation, invasion and tumorigenicity of human bladder cancer cells. Therefore, OPN may serve as a potential therapeutic target for human bladder cancer.

Osteopontin promoter polymorphisms at locus -443 are associated with metastasis and poor prognosis of human intrahepatic cholangiocarcinoma in Chinese population

PURPOSE

Osteopontin (OPN) is known to be a secreted adhesive glycoprotein. Role of OPN in human intrahepatic cholangiocarcinoma (ICC) has not been well understood. This study explored whether genetic variations in the osteopontin gene are associated with ICC risk, progression and metastasis.

MATERIAL AND METHODS

260 patients with stages I to IV between 2008 and 2013 were recruited in this study and same number healthy persons were used as control. OPN-66 T/G, -156 G/GG and -443 C/T variants were genotyped using DNA from blood lymphocytes. Chi-square test and a Fisher's exact test were used to analyze the genotype distribution between healthy subjects and patients, and further its distribution among TNM stages and incidence metastasis in patients.

RESULTS

For the variant at nt- 443 (CC), there was a significant difference between the number of patients with stage IV and those with all other stages of ICC (P < 0.01). Patients with -443 (CC) variant had significant higher incidence of lymph and distant metastasis development compared to other genotypes. For the variant at nt- 443 (CT), there was a significant difference between the number of ICC patients with stage III + IV and those with stage I + II (P < 0.01). The survival rates for ICC patients with the C/C genotype were significantly lower than for patients with the other two genotypes (C/T, T/T).

CONCLUSION

OPN -443 C/T polymorphism is a potential predictive marker of metastasis and poor prognosis in ICC patients.

Osteopontin knockdown suppresses the growth and angiogenesis of colon cancer cells

AIM: To investigate the effects of osteopontin (OPN) gene expression knockdown on colon cancer Lovo cells in vitro.

METHODS: Four candidate small interfering RNA (siRNA) constructs targeting the OPN gene and a scrambled control sequence (NC-siRNA) were synthesized and inserted into a pGPU6/GFP/Neo expression vector. After confirmation by restriction enzyme digestion and DNA sequencing, the recombinant plasmids were subsequently transfected into a human colon cancer cell line (Lovo) using a liposome transfection method. Stably transfected cells were maintained with G418 selection and referred to as Lovo-OPN-1, -2, -3, -4, and Lovo-NC cells. Knockdown efficiency of each of the four siRNA constructs was determined by real-time reverse transcription polymerase chain reaction assays and western blotting, and the construct with the most effective silencing was used for subsequent experiments. Cell proliferation, adhesion, and Matrigel invasion assays were performed to analyze the effects of OPN knockdown in stably transfected Lovo cells. The levels of four angiogenic factors, namely vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP)-2, MMP-9 and urokinase plasminogen activator were detected by enzyme-linked immunosorbent assays (ELISA).

RESULTS: Recombinant vectors containing OPN-specific and scrambled siRNA sequences were successfully constructed and stably transfected into Lovo cells. Compared with the control Lovo and Lovo-NC cells, the levels of OPN mRNA and protein expression in Lovo-OPN-1, -2, -3, and -4 were significantly reduced (all P < 0.05), with the most efficient reduction observed in Lovo-OPN-4 cells (P < 0.05). Relative to untransfected Lovo cells, OPN mRNA expression levels in Lovo-NC and Lovo-OPN-4 cells were 1.008 ± 0.067 and 0.160 ± 0.023, respectively. The relative OPN protein expression levels in Lovo, Lovo-NC, and Lovo-OPN-4 cells were 3.024 ± 0.211, 2.974 ± 0.630, and 0.121 ± 0.008, respectively. Moreover, transfection with the scrambled sequence had no effect on the expression of OPN. After 24, 48, 72, and 96 h of cultivation, absorption values at 450 nm to assess proliferation of Lovo-OPN-4 cells were 0.210 ± 0.017, 0.247 ± 0.024, 0.314 ± 0.037, and 0.359 ± 0.043, respectively, which were significantly lower than those of Lovo (0.244 ± 0.031, 0.313 ± 0.024, 0.513 ± 0.048 and 0.783 ± 0.051) and Lovo-NC cells (0.241 ± 0.029, 0.309 ± 0.022, 0.563 ± 0.023, and 0.735 ± 0.067) (all P < 0.05). The absorption values at 595 nm, which were measured in a cell adhesion assay, showed that adhesion of Lovo-OPN-4 cells (0.215 ± 0.036) was significantly decreased compared to Lovo (0.490 ± 0.037) and Lovo-NC cells (0.462 ± 0.043) (P < 0.05). The number of invasive Lovo-OPN-4 cells (16.1 ± 1.9) was also significantly decreased compared to Lovo (49.9 ± 5.4) and Lovo-NC cells (48.8 ± 4.5) (P < 0.05). ELISA assays showed significant reductions in Lovo-OPN-4 cells compared to Lovo and Lovo-NC cells with regard to the expression of VEGF (1687.85 ± 167.84 ng/L vs 2348.54 ± 143.80 ng/L and 2284.39 ± 138.62 ng/L, respectively), MMP-2 (2966.07 ± 177.36 μg/L vs 4084.74 ± 349.54 μg/L and 4011.41 ± 424.48 μg/L, respectively), MMP-9 (3782.89 ± 300.64 μg/L vs 5062.90 ± 303.02 μg/L and 4986.38 ± 300.75 μg/L, respectively) and uPA (1152.69 ± 120.79 μg/L vs 1380.90 ± 147.25 μg/L and 1449.80 ± 189.92 μg/L, respectively) (all P < 0.05).

CONCLUSION: Knockdown of OPN gene expression suppresses colon cancer cell growth, adherence, invasion, and expression of angiogenic factors.

A novel predictive equation for potential diagnosis of cholangiocarcinoma

Cholangiocarcinoma (CCA) is the second most common-primary liver cancer. The difficulties in diagnosis limit successful treatment of CCA. At present, histological investigation is the standard diagnosis for CCA. However, there are some poor-defined tumor tissues which cannot be definitively diagnosed by general histopathology. As molecular signatures can define molecular phenotypes related to diagnosis, prognosis, or treatment outcome, and CCA is the second most common cancer found after hepatocellularcarcinoma (HCC), the aim of this study was to develop a predictive model which differentiates CCA from HCC and normal liver tissues. An in-house PCR array containing 176 putative CCA marker genes was tested with the training set tissues of 20 CCA and 10 HCC cases. The molecular signature of CCA revealed the prominent expression of genes involved in cell adhesion and cell movement, whereas HCC showed elevated expression of genes related to cell proliferation/differentiation and metabolisms. A total of 69 genes differentially expressed in CCA and HCC were optimized statistically to formulate a diagnostic equation which distinguished CCA cases from HCC cases. Finally, a four-gene diagnostic equation (CLDN4, HOXB7, TMSB4 and TTR) was formulated and then successfully validated using real-time PCR in an independent testing set of 68 CCA samples and 77 non-CCA controls. Discrimination analysis showed that a combination of these genes could be used as a diagnostic marker for CCA with better diagnostic parameters with high sensitivity and specificity than using a single gene marker or the usual serum markers (CA19-9 and CEA). This new combination marker may help physicians to identify CCA in liver tissues when the histopathology is uncertain.

Molecular profiling of stroma identifies osteopontin as an independent predictor of poor prognosis in intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is the second most common type of primary cancer in the liver. ICC is an aggressive cancer with poor prognosis and limited therapeutic strategies. The identification of new drug targets and prognostic biomarkers is an important clinical challenge for ICC. The presence of an abundant stroma is a histological hallmark of ICC. Given the well-established role of the stromal compartment in the progression of cancer diseases, we hypothesized that relevant biomarkers could be identified by analyzing the stroma of ICC. By combining laser capture microdissection and gene expression profiling, we demonstrate that ICC stromal cells exhibit dramatic genomic changes. We identified a signature of 1,073 nonredundant genes that significantly discriminate the tumor stroma from nontumor fibrous tissue. Functional analysis of differentially expressed genes demonstrated that up-regulated genes in the stroma of ICC were related to cell cycle, extracellular matrix, and transforming growth factor beta (TGFβ) pathways. Tissue microarray analysis using an independent cohort of 40 ICC patients validated at a protein level the increased expression of collagen 4A1/COL4A1, laminin gamma 2/LAMC2, osteopontin/SPP1, KIAA0101, and TGFβ2 genes in the stroma of ICC. Statistical analysis of clinical and pathological features demonstrated that the expression of osteopontin, TGFβ2, and laminin in the stroma of ICC was significantly correlated with overall patient survival. More important, multivariate analysis demonstrated that the stromal expression of osteopontin was an independent prognostic marker for overall and disease-free survival.

CONCLUSION

The study identifies clinically relevant genomic alterations in the stroma of ICC, including candidate biomarkers for prognosis, supporting the idea that tumor stroma is an important factor for ICC onset and progression.

Pyruvate kinase M2 is a novel diagnostic marker and predicts tumor progression in human biliary tract cancer

BACKGROUND

The early diagnosis of biliary tract cancer (BTC) remains challenging, and there are few effective therapies. This study investigated whether the M2 isotype of pyruvate kinase (M2-PK), which serves as the key regulator of cellular energy metabolism in proliferating cells, could play a role in the diagnosis and therapy of BTC.

METHODS

Plasma and bile M2-PK concentrations were measured by enzyme-linked immunosorbent assay in 88 patients with BTC, 79 with benign biliary diseases, and 17 healthy controls. M2-PK expression was assayed in a BTC tissue array by immunohistochemistry. The role of M2-PK in tumor growth, invasion, and angiogenesis was evaluated in BTC cell lines by retrovirus-mediated M2-PK transfection and short hairpin RNA silencing techniques.

RESULTS

Sensitivity (90.3%) and specificity (84.3%) of bile M2-PK for malignancy were significantly higher than those for plasma M2-PK and serum carbohydrate antigen 19-9. M2-PK expression was specific for cancer cells and correlated with microvessel density. M2-PK positivity was a significant independent prognostic factor by multivariable analysis. Transfection of M2-PK in a negatively expressed cell line (HuCCT-1 cells) increased cell invasion, whereas silencing in an M2-PK-positive cell line (TFK cells) decreased tumor nodule formation and cellular invasion. A significant increase in endothelial tube formation was noted when supernatants from M2-PK-transfected cells were added to an in vitro angiogenesis assay, whereas supernatants from silenced cells negated endothelial tube formation.

CONCLUSIONS

Bile M2-PK is a novel tumor marker for BTC and correlates with tumor aggressiveness and poor outcome. Short hairpin RNA-mediated inhibition of M2-PK indicates the potential of M2-PK as a therapeutic target.

Gene expression-based chemical genomics identifies heat-shock protein 90 inhibitors as potential therapeutic drugs in cholangiocarcinoma

BACKGROUND

Cholangiocarcinoma (CCA) is an aggressive tumor with a poor prognosis. There is no standard therapy for CCA, and novel drugs for treating refractory CCA need to be identified.

METHODS

The authors hypothesized that, if a drug could reverse the gene expression signature of CCA, then it may inhibit the carcinogenesis of CCA and, hence, would be a potential therapeutic agent. Thus, the gene expression signatures from patients with CCA were queried using the bioinformatic method Connectivity Map, resulting in the enrichment of heat-shock protein 90 (HSP90) inhibitors with therapeutic potentials.

RESULTS

Two HSP90 inhibitors, 17-AAG (tanespimycin) and the synthetic diarylisoxazole amide resorcinol NVP-AUY922, demonstrated potent antiproliferative activity in in vitro studies. In a thioacetamide-induced animal model, NVP-AUY922 also had antitumor activity and resulted in objective tumor regression. In addition, NVP-AUY922 reduced the expression of client oncoproteins involved in CCA oncogenesis and inhibited downstream proteins of both the phosphatidylinositol 3-kinase catalytic subunit α/v-akt murine thymoma viral oncogene homolog 1 protein kinase (PIK3/AKT) pathway and the v-Ki-ras2 Kirsten rat sarcoma viral oncogene/mitogen-activated protein kinase (KRAS/MAPK) pathway.

CONCLUSIONS

Preclinical data from the current study suggest that NVP-AUY922 may be an effective treatment option for patients with CCA.

Osteopontin: an important molecule in liver diseases

Osteopontin (OPN) is a multi-functional glycoprotein that has been implicated in a number of physiological and pathological events in vivo. Recent studies have shown that abnormal changes in OPN expression occur in many liver diseases and animal models of liver diseases and may play an important role in the pathogenesis of these diseases. Elucidation of mechanisms underlying the role of OPN in the pathogenesis of different liver diseases will help identify new therapeutic targets and develop new drugs for these diseases.

Genome-wide expression patterns associated with oncogenesis and sarcomatous transdifferentation of cholangiocarcinoma

Background

The molecular mechanisms of CC (cholangiocarcinoma) oncogenesis and progression are poorly understood. This study aimed to determine the genome-wide expression of genes related to CC oncogenesis and sarcomatous transdifferentiation.

Methods

Genes that were differentially expressed between CC cell lines or tissues and cultured normal biliary epithelial (NBE) cells were identified using DNA microarray technology. Expressions were validated in human CC tissues and cells.

Results

Using unsupervised hierarchical clustering analysis of the cell line and tissue samples, we identified a set of 342 commonly regulated (>2-fold change) genes. Of these, 53, including tumor-related genes, were upregulated, and 289, including tumor suppressor genes, were downregulated (<0.5 fold change). Expression of SPP1, EFNB2, E2F2, IRX3, PTTG1, PPARγ, KRT17, UCHL1, IGFBP7 and SPARC proteins was immunohistochemically verified in human and hamster CC tissues. Additional unsupervised hierarchical clustering analysis of sarcomatoid CC cells compared to three adenocarcinomatous CC cell lines revealed 292 differentially upregulated genes (>4-fold change), and 267 differentially downregulated genes (<0.25 fold change). The expression of 12 proteins was validated in the CC cell lines by immunoblot analysis and immunohistochemical staining. Of the proteins analyzed, we found upregulation of the expression of the epithelial-mesenchymal transition (EMT)-related proteins VIM and TWIST1, and restoration of the methylation-silenced proteins LDHB, BNIP3, UCHL1, and NPTX2 during sarcomatoid transdifferentiation of CC.

Conclusion

The deregulation of oncogenes, tumor suppressor genes, and methylation-related genes may be useful in identifying molecular targets for CC diagnosis and prognosis.

An Immunohistochemical Study of Osteopontin in Pigment Gallstone Formation

Mucin glycoproteins from the gallbladder epithelium are thought to contribute to the matrix or nucleus of gallstones and other biomineralization systems. The involved acidic glycoproteins have been reported in bile and gallstones. In addition, osteopontin (Opn) is a noncollagenous acidic bone matrix glycoprotein that possesses calcium-binding properties. To investigate the role of Opn in pigment gallstone formation, the involvement of Opn in pigment gallstone formation was studied immunohistochemically in the gallbladder wall and in the stones. Staining for Opn was strongly positive in the epithelium of stone-laden gallbladders and in their stones. The stone-laden gallbladders were infiltrated by macrophages, which intensely stained for Opn. Sections of the pigment stones, under low magnification, showed a lamellar pattern of Opn immunolabeling and showed a reticular pattern under high magnification. Our results indicate that Opn, an acidic glycoprotein from the gallbladder epithelium, seems to be involved in lithiasis. Opn from macrophages and/or the epithelium seems to help form the matrix protein.

IQGAP1 and vimentin are key regulator genes in naturally occurring hepatotumorigenesis induced by oxidative stress

To identify key genes involved in the complex multistep process of hepatotumorigenesis, we reduced multivariate clinicopathological variables by using the Long-Evans Cinnamon rat, a model with naturally occurring and oxidative stress-induced hepatotumorigenesis. Gene expression patterns were analyzed serially by profiling liver tissues from rats of a naive status (4 weeks old), through to those with chronic hepatitis (26 and 39 weeks old) to tumor development (67 weeks old). Of 31 099 probe sets used for microarray analysis, 87 were identified as being upregulated in a stepwise manner during disease progression and tumor development. Quantitative real-time reverse transcription-polymerase chain reaction and statistical analyses verified that IQGAP1 and vimentin mRNA expression levels increased significantly throughout hepatotumorigenesis. A hierarchical clustering algorithm showed both genes clustered together and in the same cluster group. Immunohistochemical and western blot analyses showed similar increases in protein levels of IAGAP1 and vimentin. Finally, pathway analyses using text-mining technology with more comprehensive and recent gene-gene interaction data identified IQGAP1 and vimentin as important nodes in underlying gene regulatory networks. These findings enhance our understanding of the multistep hepatotumorigenesis and identification of target molecules for novel treatments.

Molecular Markers in the Pathogenesis of Cholangiocarcinoma: Potential for Early Detection and Selection of Appropriate Treatment

Cholangiocarcinoma (CC) is a primary malignancy that arises from cholangiocytes, the epithelial cells lining the bile duct livers. The worldwide incidence of CC is increasing and despite of combined therapeutic strategies, its prognosis remains poor. Till now surgery remains the only curative treatment modality. Over the past years, several important studies have yielded new insights into the molecular mechanisms of cholangiocarcinoma. This review focused on critical molecular player during the development from inflammation and cellular and molecular pathogenesis of this disease. The novel prophylactic and therapeutic approach deals especially the molecules involved in inflammation of cholangiocite or those related to promotion and progression of CC. The elucidation of their specific effects and interaction of this complex mechanism will accelerate the development of new biomarker for early detection and predictor factors outcome in CC.

[Physiologic and pathologic experimental models for studying cholangiocytes]

Cholangiocytes (epithelial cells lining the intra- and extrahepatic bile ducts) and hepatocytes are two major components of liver epithelia. Although cholangiocytes are less numerous than hepatocytes, they are involved in both bile secretion and diverse cellular processes such as cell-cycle phenomena, cell signaling, and interactions with other cells, matrix components, foreign organisms, and xenobiotics. Cholangiocytes are also targets in several human diseases including cholangiocarcinoma, primary sclerosing cholangitis, autoimmune cholangitis, and vanishing bile-duct syndrome. The rapid advances in experimental biology technologies are greatly expanding interest in and knowledge of the physiology and pathophysiology of cholangiocytes. This review focuses on the progress of in vivo and in vitro experimental models in elucidating the physiologic functions of cholangiocytes and the pathophysiology of various cholangiopathies. The following aspects are reviewed: isolation of cholangiocytes from the liver and their heterogeneity, various culture systems, establishment of cholangiocyte cell lines, isolation and usage of intrahepatic bile-duct units, three-dimensional modeling of the bile duct, experimental models for inducing cholangiocyte proliferation, and various cholangiopathies such as cholangiocarcinoma, primary sclerosing cholangitis, and autoimmune cholangitis.