Diagnosis, Staging, and Treatment of Cholangiocarcinoma

A prospective proteomic-based study for identifying potential biomarkers for the diagnosis of cholangiocarcinoma

BACKGROUND

Cholangiocarcinoma (CCA) is becoming a common fatal hepatic tumor. Early detection of CCA is hampered by the absence of a sufficiently accurate and noninvasive diagnostic test. Proteomic analysis would be a powerful tool to identify potential biomarkers of this cancer.

AIMS

This study aims to identify new protein markers that are specific for CCA using proteomic approaches and to evaluate the performance of S100 calcium-binding protein A9 (S100A9) and chaperonin-containing TCR1, subunit 3 (CCTγ) as diagnostic markers for screening test of CCA.

METHODS

Two-dimensional differential gel electrophoresis (2-D DIGE) coupled with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry were used to analyze and screen biomarker candidates in the proteomes of five human CCA samples and five healthy control samples. Subsequently, two potential biomarkers, S100A9 and CCTγ, were chosen for validation and analysis by immunohistochemical methods using CCA tissue microarrays.

RESULTS

Twenty protein spots were significantly elevated and five protein spots were downregulated in all patients (p < 0.05). The positive rate was significantly higher in patients with CCA (48 ± 35%) compared with the normal liver control group (5 ± 10%, p < 0.001), the hepatocellular carcinoma group (15 ± 20%, p < 0.001), and the cirrhosis group (12 ± 16%, p < 0.001). A greater proportion of patients with CCA were positive for CCTγ (72 ± 18%) compared with the normal liver control group (43 ± 22%, p < 0.001), the hepatocellular carcinoma group (45 ± 20%, p < 0.001), and the cirrhosis group (39 ± 25%, p < 0.001).

CONCLUSIONS

Combined comparative proteomic analysis using 2-D DIGE and MALDI-TOF is an effective method for identifying differentially expressed proteins in CCA tissues. The expression of S100A9 and CCTγ showed promise as novel diagnostic markers for CCA.

Management of hilar biliary strictures

Biliary strictures at the liver hilum are caused by a heterogeneous group of benign and malignant conditions. In the absence of a clear-cut benign etiology, i.e. bile duct damage during surgery, hilar biliary strictures remain a diagnostic and therapeutic challenge for which a multidisciplinary approach is often necessary. A definitive diagnosis can be achieved in only 40-60% of the patients, while in all the other cases strictures are treated as though they are malignant until surgical pathology determines otherwise. Surgical resection is the only treatment that prolongs survival in patients with malignant strictures. Because these tumors frequently extend longitudinally via the hepatic ducts into the liver parenchyma, partial hepatic resection has been gradually added to biliary resection to ensure tumor-free surgical margins. For unresectable cases, endoscopic stenting of biliary obstruction is considered the preferred palliation modality to relieve pruritus, cholangitis, pain and jaundice, while the percutaneous approach has been reserved for cases of failure. Other modalities of treatment such as radiotherapy, chemotherapy, and photodynamic therapy currently remain investigational. For benign post surgical hilar strictures, surgical repair can be difficult and requires specific skills and experience. As an alternative, a multi-stent technique with endoscopic placement of an increasing number of stents over time until complete resolution of the stricture has been proposed.

[F-18]fluorodeoxyglucose positron emission tomography and positron emission tomography: computed tomography in recurrent and metastatic cholangiocarcinoma

OBJECTIVES

We retrospectively assessed the diagnostic utility of dedicated positron emission tomography (PET) and hybrid PET-computed tomography (CT) scans with [F-18]fluorodeoxyglucose (FDG) in the imaging evaluation of patients with known or suspected recurrent and metastatic cholangiocarcinoma.

METHODS

The study group included 24 patients (13 males and 11 females; age range, 34-75 years) with known or suspected recurrent and metastatic cholangiocarcinoma. We performed 8 dedicated PET scans (Siemens 953/A, Knoxville, Tenn) in 8 patients and 24 hybrid PET-CT scans (Siemens Biograph, Knoxville, Tenn) in 16 patients. Four patients underwent both pretreatment and posttreatment scans. Nonenhanced CT transmission scans were obtained for attenuation correction after administration of oral contrast material. PET images were obtained 60 minutes after the intravenous administration of 15 mCi (555 MBq) FDG. Prior treatments included surgery alone in 12 patients, surgery and chemotherapy in 6 patients, and surgery and combined chemoradiation therapy in 6 patients. Diagnostic validation was conducted through clinical and radiologic follow-up (2 months to 8 years).

RESULTS

PET and CT were concordant in 18 patients. PET-CT correctly localized a hypermetabolic metastatic lesion in the anterior subdiaphragmatic fat instead of within the liver and was falsely negative in intrahepatic infiltrating type cholangiocarcinoma. PET was discordant with CT in 6 patients. PET was negative in an enlarged right cardiophrenic lymph node on CT, which remained stable for 1 year. In 1 patient, PET-CT scan showed hypermetabolic peritoneal disease in the right paracolic gutter without definite corresponding structural abnormalities, which was subsequently confirmed on a follow-up PET-CT scan performed 6 months after the initial study, at which time peritoneal nodular thickening was evident on concurrent CT. PET-CT documented the progression of locally recurrent and metastatic disease in another patient based on interval appearance of several new hypermetabolic lesions and significant increase in the standardized uptake values of the known lesions despite little interval change in the size and morphologic character of lesions on concurrent CT. It was also helpful in excluding metabolically active disease in patients with contrast enhancement at either surgical margin of hepatic resection site or focally within hepatic parenchyma and in an osseous lesion. Overall, based on the clinically relevant patient basis for detection of recurrent and metastatic cholangiocarcinoma, the sensitivity and specificity of PET (alone and combined with CT) were 94% and 100% and, for CT alone, were 82% and 43%, respectively.

CONCLUSIONS

FDG PET and PET-CT are useful in the imaging evaluation of patients with cholangiocarcinoma (except for infiltrating type) for detection of recurrent and metastatic disease and for assessment of treatment response. In particular, the combined structural and metabolic information of PET-CT enhances the diagnostic confidence in lesion characterization.

Expression of WW domain-containing oxidoreductase gene in patients with extrahepatic cholangiocarcinoma

AIM: To determine the expression of WW domain-containing oxidoreductase (WWOX) messenger RNA (mRNA) and protein, and evaluate its clinicopathological significance in human extrahepatic cholangiocacinoma (ECC).

METHODS: Real-time reverse transcription-polymerase chain reaction and immunohistochemistry (UIP method) were used to detect the expression of WWOX mRNA and protein respectively in 21 ECC patients and 5 cases of normal bile duct tissues. The results were comparatively analyzed with the clinicopathological characteristics.

RESULTS: The expression of WWOX mRNA was significantly lower in ECC than that in normal bile duct tissues (8.936 × 10^-7 ± 3.253 × 10^-7vs 1.079 × 10^-6 ± 1.735 × 10^-7, P < 0.001), and the loss of mRNA was observed in 47% of the cases (t = 10.145, P < 0.001). Loss of WWOX protein expression was found in 57% of ECC specimens. Both mRNA and protein expression had a significant correlation with the histological grading, and the correlation coefficients were -0.583 and -0.840, respectively. However, WWOX expression had no correlations with other clinicopathological factors such as age, sex, clinical staging or the status of preoperative hepatic function (P > 0.05). Poorly differentiated ECC had markedly lower expression of WWOX than moderately or well differentiated one (P < 0.05).

CONCLUSION: Alterations of WWOX expression may be involved in the tumorigenesis of cholangiocarcinoma, which may serve as an indicator for predicting the invasion of ECC.

Lysophosphatidylcholine suppresses apoptotic cell death by inducing cyclooxygenase-2 expression via a Raf-1 dependent mechanism in human cholangiocytes

PURPOSE

The high incidence of biliary tract carcinoma in patients with anomalous pancreaticobiliary ductal junction (APBDJ) implicates that a compositional alteration in bile may contribute to the genesis of this cancer. Lysophosphatidylcholine (LPC) is generated in the bile of these patients. Given the role of cyclooxygenase-2 (COX-2) in biliary tract carcinogenesis, we postulated that LPC induces COX-2 in cholangiocytes.

METHODS

The effect of LPC on COX-2 expression in cholangiocytes was evaluated by immunoblot analysis, real-time PCR and reporter gene assay. Apoptosis was induced by TRAIL treatment, and quantified using DAPI staining.

RESULTS

Lysophosphatidylcholine increased COX-2 protein expression in cholangiocytes in a concentration- and time-dependent manner. LPC-induced Raf-1 activation was responsible for this COX-2 induction. Accordingly, LPC increased COX-2 mRNA levels in a Raf-1 dependent manner by stabilizing COX-2 mRNA. Finally, LPC attenuated TRAIL-mediated apoptosis through a COX-2/PgE2 dependent mechanism.

CONCLUSIONS

Collectively, these results implicate that LPC inhibits cholangiocyte apoptosis by inducing COX-2 expression via a Raf-1 dependent mechanism. This anti-apoptotic signaling may participate in biliary tract carcinogenesis in APBDJ patients, and therefore, its interruption may be a viable chemopreventative strategy.

Detection of response-predicting mutations in the kinase domain of the epidermal growth factor receptor gene in cholangiocarcinomas

PURPOSE

Epidermal growth factor receptor (EGFR) signalings have recently been implicated in the genesis and progression of cholangiocarcinomas. Thus, the EGFR kinase inhibitor appears to be promising in the treatment of this cancer. The response-predicting mutations in the tyrosine kinase domain of EGFR gene have recently been detected in non-small cell lung cancers. This study was, therefore, to investigate if these mutations are also found in cholangiocarcinomas.

METHODS

Twenty-two consecutive cholangiocarcinoma patients who underwent surgical resection were enrolled. Their resected paraffin-embedded cholangiocarcinoma specimens were used for mutation analysis, which was performed by DNA sequencing of exons 18, 19 and 21 in the EGFR gene. Clinical characteristics were compared between each group according to the presence or absence of mutations.

RESULTS

Three patients (13.6%) harbored EGFR mutations. All the mutations found were deletions in exon 19. Mutations were more common in intra-hepatic or poorly differentiated tumors. Differences in age, sex, stage at diagnosis and survival were not observed between mutation-positive and -negative patients.

CONCLUSIONS

This study, for the first time, demonstrates that a subset of cholangiocarcinoma patients has response-predicting EGFR mutations. Therefore, a highly selected application of the EGFR kinase inhibitor would be therapeutically effective in these patients.

Enhanced epidermal growth factor receptor activation in human cholangiocarcinoma cells

BACKGROUND/AIMS

Epidermal growth factor receptor (EGFR) signaling has been implicated in the genesis and progression of cholangiocarcinoma. However, the characteristics of EGFR signaling in cholangiocarcinoma cells have not been characterized. Thus, we attempted to more fully characterize EGF/EGFR signaling in human cholangiocarcinoma cells.

METHODS

EGFR phosphorylation and ubiquitination were evaluated using immunoblot techniques. EGFR internalization was analyzed by immunofluorescent staining of EGFR or by immunoblot analysis for biotinylated EGFR. Cell growth was assessed using the MTS assay.

RESULTS

EGFR activation was sustained following EGF stimulation in cholangiocarcinoma cells as compared to hepatoma cells. This prolonged EGFR activation resulted in extended p42/44 MAPK activation in cholangiocarcinoma cells. Despite ubiquitination, EGFR activation-dependent internalization was defective in cholangiocarcinoma cells. Cell growth was increased in cholangiocarcinoma cells following EGF stimulation as compared to hepatoma cells, and this was significantly attenuated by EGFR kinase inhibitors. The EGFR kinase inhibitors also significantly decreased COX-2 expression in cholangiocarcinoma cells, while this was not evident in hepatoma cells.

CONCLUSIONS

The results demonstrate that cholangiocarcinoma cells exhibit sustained EGFR activation due to defective receptor internalization. As EGFR kinase inhibitors effectively attenuated cellular growth, these agents may be therapeutically efficacious in human cholangiocarcinoma.

Mac-2-binding protein is a diagnostic marker for biliary tract carcinoma

BACKGROUND

Biliary tract carcinoma is a deadly disease, accounting for nearly 4500 malignancy-related deaths each year in the United States. Early detection has the potential to improve survival for patients with biliary tract malignancies, enabling curative surgical resection. Early detection approaches would benefit from an accurate, minimally invasive diagnostic test. To identify novel diagnostic markers, the authors recently completed a comprehensive proteomic study of bile samples from patients with biliary carcinoma. One of the proteins identified by tandem mass spectrometry was Mac-2-binding protein (Mac-2BP). The authors evaluated the performance of Mac-2BP and its ligand, galectin-3, as diagnostic markers for patients with biliary carcinoma.

METHODS

Levels of Mac-2BP, galectin-3, and CA19-9 were measured using an enzyme-linked immunosorbent assay (ELISA) in bile samples from patients with biliary tract carcinoma (n = 26), benign biliary conditions (n = 32), and primary sclerosing cholangitis (n = 20). Serum levels of Mac-2BP and galectin-3 also were determined using ELISA. Mac-2BP tissue expression was investigated by immunohistochemical methods using a biliary carcinoma tissue microarray.

RESULTS

Biliary Mac-2BP levels were elevated by a factor of approximately 3 in the biliary carcinoma group compared with the group of patients who had PSC or another type of nonneoplastic biliary disease. In contrast, Mac-2BP levels were not elevated in serum samples from patients with biliary carcinoma. According to the immunohistochemical analysis, Mac-2BP was expressed in 34 of 36 patients (94.4%) with biliary tract carcinoma. As a diagnostic marker for biliary carcinoma, Mac-2BP levels were as accurate as biliary CA19-9 levels, with an area under the curve (AUC) of 0.70 on receiver operator characteristic analysis. The use of both of these bile markers in combination, however, led to significantly better diagnostic accuracy compared with the accuracy achieved using CA19-9 alone (AUC, 0.75; P < 0.001). Serum and biliary galectin-3 levels did not differ in the biliary carcinoma group relative to the control groups.

CONCLUSIONS

Biliary Mac-2BP levels, especially when used in conjunction with biliary CA19-9 levels, showed promise as a novel diagnostic marker for biliary tract carcinoma.

Inducible nitric oxide synthase upregulates cyclooxygenase-2 in mouse cholangiocytes promoting cell growth

Both inducible nitric oxide (NO) synthase (iNOS) and cyclooxygenase-2 (COX-2) have been implicated in the biliary tract carcinogenesis. However, it is not known whether these inflammatory mediators are induced by interdependent or parallel pathways. Because iNOS activity has been associated with diverse gene expression, the aim of this study was to determine whether iNOS induces COX-2. To address this objective, immortalized, but nonmalignant, murine cholangiocytes, 603B cells were employed for these studies. Both iNOS and COX-2 protein and mRNA were expressed in these cells. However, iNOS inhibition with either N-[3-(aminomethyl) benzyl]acetamidine or stable transfection with an iNOS antisense construct inhibited COX-2 mRNA and protein expression, an effect that was reversed by NO donors. COX-2 mRNA expression in 603B cells was reduced by pharmacological inhibitors of the p38 MAPK and JNK1/2 pathways. In contrast, neither inhibitors of the soluble guanylyl cyclase inhibitor/protein kinase G nor p42/44 MAPK pathways attenuated COX-2 mRNA expression. Finally, 603B cells grew at a rate threefold greater than 603B-iNOS antisense cells. The low growth rate of 603B-iNOS antisense cells could be restored to near that of the parent cell line with exogenous PGE(2.) In conclusion, iNOS induces COX-2 expression in cholangiocytes, which promotes cell growth. COX-2 induction may contribute to iNOS-associated carcinogenesis.

Hilar cholangiocarcinoma: surgical and endoscopic approaches

HCCa remains an uncommon malignancy, though increasing use of more radical surgery has led to prolonged survival in those patients who undergo curative resection. The extent of these resections suggest that the best results are likely to be obtained in centers with the resources and experience to conduct these operations in a safe fashion. Until major advances in the systemic therapy of HCCa are made, however, the management should focus on optimal preoperative imaging and palliation of jaundice with improvement in quality of life.

Oxysterols induce cyclooxygenase-2 expression in cholangiocytes: implications for biliary tract carcinogenesis

Cyclooxygenase-2 (COX-2), which is expressed by cholangiocytes in biliary tract disorders, has recently been implicated in biliary tract carcinogenesis. The mechanisms responsible for this COX-2 expression remain unclear. In human diseases, bile contains oxygenated derivatives of cholesterol (oxysterols) which possess diverse biological properties. Therefore, we determined if oxysterols modulate COX-2 expression. The effect of an oxysterol (22(R)-hydroxycholesterol, 22-HC) on COX-2 expression in KMBC cells, a human cholangiocarcinoma cell line, was examined. 22-HC enhanced COX-2 protein expression. This oxysterol activated p42/44 and p38 MAPK, but not JNK 1/2. A p42/44 MAPK inhibitor did not block COX-2 induction, while p38 MAPK inhibitor effectively attenuated COX-2 induction. Although COX-2 mRNA levels were increased by 22-HC, this increase was not transcriptionally regulated, as 22-OH did not increase activity in a COX-2 promoter gene assay. In contrast, COX-2 mRNA stability was augmented by 22-HC treatment, and this effect was reversed by a p38 MAPK inhibitor. In conclusion, the results demonstrate that the oxysterol 22-HC stabilizes COX-2 mRNA via a p38 MAPK-dependent mechanism. This enhanced COX-2 protein expression by oxysterols may participate in the genesis and progression of cholangiocarcinoma.