Preneoplastic conditions underlying bile duct cancer

Genetic alterations during the neoplastic cascade towards cholangiocarcinoma in primary sclerosing cholangitis

Carcinogenesis of primary sclerosing cholangitis (PSC)-associated cholangiocarcinoma (CCA) is largely unexplored. Improved understanding of the molecular events involved may guide development of novel avenues for rational clinical management. We aimed to assess the genetic alterations during progression of the neoplastic cascade from biliary dysplasia towards CCA in PSC. Forty-four resection specimens or biopsies of PSC patients with biliary dysplasia (n = 2) and/or CCA (n = 42) were included. DNA was extracted from sections of formalin-fixed paraffin-embedded tissue blocks with dysplasia (n = 23), CCA (n = 69), and nonneoplastic tissue (n = 28). A custom-made next-generation sequencing (NGS) panel of 28 genes was used for mutation and copy number variation (CNV) detection. In addition, CNVs of CDKN2A, EGFR, MCL1, and MYC were examined by fluorescence in situ hybridization. Alterations in 16 low-grade dysplasia samples included loss of FGFR1 (19%), CDKN2A (13%), and SMAD4 (6%), amplification of FGFR3 (6%), EGFR (6%), and ERBB2 (6%), and mutations in SMAD4 (13%). High-grade dysplasia (n = 7) is characterized by MYC amplification (43%), and mutations in ERBB2 (71%) and TP53 (86%). TP53 mutations are the most common aberrations in PSC-CCA (30%), whereas mutations in KRAS (16%), GNAS (14%), and PIK3CA (9%) are also common. In conclusion, PSC-CCA exhibits a variety of genetic alterations during progression of the neoplastic cascade, with mainly CNVs being present early, whereas mutations in ERBB2, TP53, and KRAS appear later in the development of CCA. These findings are promising for the development of NGS-guided diagnostic strategies in PSC-CCA. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Imaging Features of Premalignant Biliary Lesions and Predisposing Conditions with Pathologic Correlation

Biliary malignancies include those arising from the intrahepatic and extrahepatic bile ducts as well as the gallbladder and hepatopancreatic ampulla of Vater. The majority of intrahepatic and extrahepatic malignancies are cholangiocarcinomas (CCAs). They arise owing to a complex interplay between the patient-specific genetic background and multiple risk factors and may occur in the liver (intrahepatic CCA), hilum (perihilar CCA), or extrahepatic bile ducts (distal CCA). Biliary-type adenocarcinoma constitutes the most common histologic type of ampullary and gallbladder malignancies. Its prognosis is poor and surgical resection is considered curative, so early detection is key, with multimodality imaging playing a central role in making the diagnosis. There are several risk factors for biliary malignancy as well as predisposing conditions that increase the risk; this review highlights the pertinent imaging features of these entities with histopathologic correlation. The predisposing factors are broken down into three major categories: (a) congenital malformations such as choledochal cyst and pancreaticobiliary maljunction; (b) infectious or inflammatory conditions such as parasitic infections, hepatolithiasis, primary sclerosing cholangitis, and porcelain gallbladder; and (c) preinvasive epithelial neoplasms such as biliary intraepithelial neoplasm, intraductal papillary neoplasm of the bile duct, intra-ampullary papillary tubular neoplasm, and intracholecystic papillary neoplasm of the gallbladder. Recognizing the baseline features of these premalignant biliary entities and changes in their appearance over time that indicate the advent of malignancy in high-risk patients can lead to early diagnosis and potentially curative management. An invited commentary by Volpacchio is available online. Online supplemental material is available for this article. ^©RSNA, 2022.

Preneoplastic lesions in the liver: Molecular insights and relevance for clinical practice

Hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) are the most frequent primary liver cancers, accounting for approximately 80% and 15%, respectively. HCC carcinogenesis occurs mostly in cirrhosis and is a complex multi-step process, from precancerous lesions (low-grade and high-grade dysplastic nodules) to progressed HCC. During the different stages of liver carcinogenesis, there is an accumulation of pathological, genetic and epigenetic changes leading to initiation, malignant transformation and finally tumour progression. In contrast, a small subset of HCC occurs in normal liver from the transformation of hepatocellular adenoma (HCA), a benign hepatocellular tumour. The recent molecular classification enables to stratify HCAs according to their risk of complication, in particular malignant transformation, associated with mutations in exon 3 of the catenin beta 1 (CTNNB1) gene. Cholangiocarcinoma (CCA) derives from the multistep malignant transformation of preneoplastic lesions, like biliary intraepithelial neoplasia (BilIN) and intraductal papillary neoplasm of the bile duct (IPNB), for which a pre-operative diagnosis remains difficult. Different genetic alterations are involved in BilIN and IPNB progression, leading to the development of tubular or intestinal adenocarcinoma. The aims of this review are to describe the main clinical and molecular features of preneoplastic lesions leading to the development of HCC and CCA, their implications in clinical practice and the perspectives for future research.

Long-term Proton Pump Inhibitor Administration Caused Physiological and Microbiota Changes in Rats

Proton pump inhibitors (PPIs) are used for the long-term treatment of gastroesophageal disorders and the non-prescription medicines for acid reflux. However, there is growing concerns about PPI misuse, overuse and abuse. This study aimed to develop an animal model to examine the effects of long-term use of PPI in vivo. Twenty one Wistar rats were given omeprazole orally or intravenously for 30 days, and caerulein as a positive control. After euthanization, the serum and stool were collected to perform MS-based quantitative analysis of metabolites. We carried out 16S-based profiling of fecal microbiota, assessed the expression of bile acid metabolism regulators and examined the immunopathological characteristics of bile ducts. After long-term PPI exposure, the fecal microbial profile was altered and showed similarity to those observed in high-fat diet studies. The concentrations of several metabolites were also changed in various specimens. Surprisingly, morphological changes were observed in the bile duct, including ductal epithelial proliferation, micropapillary growth of biliary epithelium, focal bile duct stricture formation and bile duct obstruction. These are characteristics of precancerous lesions of bile duct. FXR and RXRα expressions were significantly reduced, which were similar to that observed in cholangiocarcinoma in TCGA and Oncomine databases. We established a novel animal model to examine the effects of long-term use of omeprazole. The gut microbes and metabolic change are consequences of long-term PPI exposure. And the results showed the environment in vivo tends to a high-fat diet. More importantly, we observed biliary epithelial hyperplasia, which is an indicator of a high-fat diet.

DNA Methylation Markers Improve the Sensitivity of Endoscopic Retrograde Cholangiopancreatography-Based Brushing Cytology in Extrahepatic Cholangiocarcinoma

Endoscopic retrograde cholangiopancreatography with brushed cytology is still the standard method for the diagnosis of extrahepatic cholangiocarcinoma in obstructive jaundice; however, the diagnostic yield is limited. To improve the diagnostic sensitivity, DNA methylation analysis is an attractive candidate, since this may constitute a stable marker in brushed specimens. Therefore, this study aims to evaluate the importance of such epigenetic markers in brushed biliary cells from patients with obstructive jaundice for the diagnosis of extrahepatic cholangiocarcinoma. The cells examined were those that were left over from brushed cytology done during routine endoscopic retrograde cholangiopancreatography of patients with extrahepatic cholangiocarcinoma. The methylation states of HOXA1, RASSF1A, P16, and NEUROG1 genes in extrahepatic cholangiocarcinoma were measured by quantitative methylation-specific polymerase chain reaction and compared between brushed biliary cells and normal gall bladder epithelial cells. The results showed that the sensitivity of the methylation index measurements of HOXA1 and NEUROG1 genes from brushed samples was markedly superior to that of standard cytology. In conclusion, measurement of the DNA methylation status of HOXA1 and NEUROG1 genes in leftover brushed biliary cells might serve as a useful supplement in the detection of malignant biliary obstruction by increasing the sensitivity of diagnosis by routine cytology.

Imaging Monitoring of Kupffer Cell Function and Hepatic Oxygen Saturation in Preneoplastic Changes During Cholangiocarcinogenesis

We investigated serial changes of the Kupffer cell (KC) function and hepatic oxygen saturation (sO₂) using contrast-enhanced ultrasound imaging (CEUS) and photoacoustic imaging (PAI) in preneoplastic changes during cholangiocarcinogenesis induced by obstructive cholangitis and N-nitrosodimethylamine in a mouse model. The CEUS and PAI were performed to assess Sonazoid contrast agent uptake by KC and changes in the sO₂ of liver parenchyma. An extensive bile ductular reaction, cystic dilatation, and epithelial hyperplasia with dysplastic changes were noted in the experimental group. During the preneoplastic changes, the parenchymal echogenicity on the Kupffer-phase of CEUS was continuously decreased in the experimental group, and which means that the Sonazoid phagocytosis by KC was decreased. The number of KCs was increased in the CD68 analysis, indicating functionally impaired KCs. There was a simultaneous serial decrease in sO₂ on PAI measurement of the experimental group during the preneoplastic changes. The experimental group also showed significantly higher expression of hypoxia-inducible factor-1α and vascular endothelial growth factor protein. Our study demonstrated that KC dysfunction and hypoxic environmental changes were the factors influencing preneoplastic change during cholangiocarcinogenesis, and we could non-invasively monitor these changes using CEUS and PAI.

FoxP3 demethylation is increased in human colorectal cancer and rat cholangiocarcinoma tissue

OBJECTIVES

FoxP3 expression is a marker for Tregs which are known to be involved in tumor immunity. We aimed to evaluate FoxP3 promoter demethylation in human colorectal cancer (CRC) and rat intrahepatic cholangiocarcinoma (ICC).

DESIGN AND METHODS

Bisulfite-treated genomic DNA templates of shock frozen paired samples were studied from 13 anonymous CRC patients and from 10 male rats (n=6 ICC induced by thioacetamide and n=4 age-matched controls). Real-time PCR was carried out using a LightCycler 480 system. Human FoxP3 and CD3 promoter demethylations were estimated using previously described assays; and rat FoxP3 promoter demethylation using a newly developed assay.

RESULTS

A significant 3.5-fold increase of the demethylation in FoxP3 promoter region was found in human CRC and rat ICC (P<0.05). The average frequency of cells with FoxP3 demethylation in patients suffering from CRC was 0.26% in normal tissue and 0.92% in tumor tissue (n=11 paired samples). Although, no significant difference was found between the mean frequency of CD3 demethylation in normal tissue (4.80%, n=6) and in tumor tissue (4.14%, n=6) from CRC patients, the ratio of demethylated CD3/FoxP3 promoter areas was significantly lower in tumor specimens (P<0.05). Using our novel assay, we found a significant increase in mean frequencies of cells with FoxP3 demethylation in rats with ICC (7.42%, n=6) in comparison to controls (2.14%, n=4).

CONCLUSION

FoxP3 seems to be an interesting biomarker for immune response to epithelial tumors. Functional consequences from the increase of Tregs remain to be demonstrated. Further studies with outcome data are necessary.