Ki-ras point mutations and proliferation activity in biliary tract carcinomas

Promising Molecular Targets for the Targeted Therapy of Biliary Tract Cancers: An Overview

Biliary tract cancer (BTC) is a leading cause of cancer-related death, due to the limited benefits of current systematic therapies and the heterogeneity of the tumor itself. High heterogeneity means that the clinical and molecular features vary between different subtypes of BTC, while the underlying molecular mechanisms remain unclear. Targeted therapy, where inhibitors are developed to selectively combine with targeted molecules in order to block abnormal signaling pathways in BTC, has shown promise as an emerging form of treatment for various types of cancer. In this article, a comprehensive review is conducted to examine potential molecular targets for BTC targeted therapy and their mechanisms. Furthermore, preliminary data published from clinical trials is utilized to analyze the main drugs used to combat BTC. The collective information presented in this article has provided useful insights into the current understanding of BTC.

Anti-EGFR Monoclonal Antibodies in Advanced Biliary Tract Cancer: A Systematic Review and Meta-analysis

BACKGROUND

Despite several clinical trials and advances in understanding the genetic basis of biliary tract cancer (BTC), the addition of epidermal growth factor receptor (EGFR) targeted therapy does not seem to enhance the activity of first-line chemotherapy (CHT).

MATERIALS AND METHODS

We carried out a meta-analysis of available randomized clinical trials to assess the efficacy and safety of gemcitabine-based first-line CHT plus monoclonal antibodies against EGFR (EGFR-mAbs) in advanced or metastatic BTC.

RESULTS

In the overall population, the pooled hazard ratio for overall (OS) and progression-free (PFS) survival were 0.82 (95% confidence interval=0.64-1.06) and 0.88 (95% confidence intervaI=0.73-1.08), respectively. No differences were detected in objective response rate between the two groups. Patients treated with gemcitabine-based CHT plus EGFR-mAbs showed a statistically significant increased risk of grade 3-4 neutropenia, grade 3-4 thrombocytopenia and especially grade 3-4 skin rash.

CONCLUSION

The addition of EGFR-mAbs to gemcitabine-based first-line CHT does not significantly improve overall and progression-free survival, nor the objective response rate in patients with advanced BTC and increases the risk of hematological and cutaneous adverse drug events.

Biliary tract cancers: current knowledge, clinical candidates and future challenges

Biliary tract cancers (BTCs) are rare with poor prognosis. Due to the advent of genomic sequencing, new data have emerged regarding the molecular makeup of this disease. To add to the complexity, various subtypes also harbor a varied genetic composition. The commonly mutated genes associated with this cancer are KRAS, EGFR, IDH, FGFR and BAP1. Various clinical studies are looking at targeting these genetic mutations. Another therapeutic area of note is the potential for the use of immunotherapy in patients with BTC. Although BTC may be a result of chronic inflammation, this does not necessarily translate into increased immunogenicity. This literature review discusses the diverse molecular and immune-related pathways in patients with BTC and their potential therapeutic implications.

Intra-pancreatic Distal Bile Duct Carcinoma is Morphologically, Genetically, and Clinically Distinct from Pancreatic Ductal Adenocarcinoma

PURPOSE

Differentiating intra-pancreatic distal bile duct carcinoma invading the pancreas from pancreatic ductal adenocarcinomas (PDAC) surrounding the distal common bile duct (CBD) can be challenging. Our aim is to identify clinical, morphological, and genetic features characteristic of intra-pancreatic distal bile duct carcinoma.

METHODS

Clinicopathologic data of 550 patients undergoing a pancreaticoduodenectomy between September 1990 and May 2008 were reviewed. KRAS status was assessed with mass-spectrometric genotyping.

RESULTS

Ninety-seven patients with intra-pancreatic adenocarcinomas surrounding the CBD were identified; slides were available for 80. Two relationships with the CBD were recognized as follows: type I (n = 42): cancer grew concentrically around the CBD and type II (n = 38): cancer grew asymmetrically around the CBD. Type I adenocarcinomas were associated with high-grade biliary dysplasia (45 vs. 13 %; p = 0.003); type II were associated with high-grade pancreatic intra-epithelial neoplasia (PanIN-2 or -3) (39 vs. 9 %; p = 0.003). Type I tumors had a better median survival (46 months) compared to type II (23 months) or other PDAC (20 months) (p < 0.001). Mutated KRAS was identified in 3/26 (11 %) type I and 20/21 (95 %) type II cancers (p < 0.001). There may be poorer survival in the presence of a KRAS mutation than wild-type KRAS (22.9 vs. 41.6 months; p = 0.3).

CONCLUSIONS

Distal periductal adenocarcinomas fall into two distinct groups with biologic, morphologic and genetic differences. Those growing symmetrically around the CBD are more likely to be intra-pancreatic distal bile duct carcinomas and are associated with improved survival whereas cancers with asymmetric growth are more likely to have KRAS mutations and to be PDACs. These findings facilitate a more accurate histopathological diagnosis, which could improve patient selection for therapeutic trials.

Cholangiocarcinoma with intraductal tubular growth pattern versus intraductal papillary growth pattern

Intraductal neoplasms of the bile duct are macroscopically characterized by exophytic or polypoid growth patterns and have a favorable prognosis. Although some tumors with a predominantly tubular microscopic pattern have been reported, they have not been well characterized clinicopathologically. The purpose of the present study was to compare the newly recognized cholangiocarcinoma with an intraductal tubular growth pattern and cholangiocarcinoma with an intraductal papillary growth pattern and to investigate the pathological and prognostic significance of the former. This study analyzed 161 patients with tumors with exophytic or polypoid growth patterns from a large series of 733 cholangiocarcinoma cases surgically resected from January 1998 to May 2013. The study patients were divided into two groups: those whose tumors showed a predominantly tubular growth pattern (n=52) and those whose tumors exhibited a predominantly papillary growth pattern (n=109). Tubular growth pattern was associated with combined vascular resection and the absence of macroscopic mucin. Several histological indexes were significantly higher for the tubular growth pattern than the papillary one, including tubular adenocarcinoma, depth of invasion, microscopic lymphatic invasion, venous invasion, perineural invasion, and necrosis. Although the survival curves overlapped (P=0.693), the rate of liver metastasis was significantly higher for the tubular growth pattern than for the papillary one (P=0.012). Genomic DNA analysis focusing on somatic mutations in codons 12 and 13 of KRAS and codon 600 of BRAF revealed only one (4%) KRAS and no BRAF mutation among the 25 tubular cases examined. In conclusion, the tubular growth pattern exhibited differences in some histologic indexes, in addition to a higher hepatic metastasis rate and a lower KRAS mutation frequency, compared with the papillary growth pattern, but no difference in prognosis was observed. The distinctiveness of this tubular neoplasm should be further examined in the future.

Perioperative Management of Hilar Cholangiocarcinoma

BACKGROUND

Cholangiocarcinoma is the most common primary tumor of the biliary tract although it accounts for only 2 % of all human malignancies. We herein review hilar cholangiocarcinoma including its risk factors, the main classification systems for tumors, current surgical management of the disease, and the role chemotherapy and liver transplantation may play in selected patients.

METHODS

We performed a comprehensive literature search using PubMed, Medline, and the Cochrane library for the period 1980-2015 using the following MeSH terms: "hilar cholangiocarcinoma", "biliary cancer", and "cholangiocarcinoma". Only recent studies that were published in English and in peer reviewed journals were included.

FINDINGS

Hilar cholangiocarcinoma is a disease of advanced age with an unclear etiology, most frequently found in Southeast Asia and relatively rare in Western countries. The best chance of long-term survival and potential cure is surgical resection with negative surgical margins, but many patients are unresectable due to locally advanced or metastatic disease at diagnosis. As a result of recent efforts, new methods of management have been identified for these patients, including preoperative portal vein embolism and biliary drainage, neoadjuvant chemotherapy with subsequent transplantation, and chemoradiation therapy.

CONCLUSION

Current management of hilar cholangiocarcinoma depends on extent of the tumor at presentation and includes surgical resection, liver transplantation, portal vein embolization, and chemoradiation therapy. Our understanding of hilar cholangiocarcinoma has improved in recent years and further research offers hope to improve the outcome in patients with these rare tumors.

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.

Patterns of chromosomal copy-number alterations in intrahepatic cholangiocarcinoma

Background

Intrahepatic cholangiocarcinomas (ICC) are relatively rare malignant tumors associated with a poor prognosis. Recent studies using genome-wide sequencing technologies have mainly focused on identifying new driver mutations. There is nevertheless a need to investigate the spectrum of copy number aberrations in order to identify potential target genes in the altered chromosomal regions. The aim of this study was to characterize the patterns of chromosomal copy-number alterations (CNAs) in ICC.

Methods

53 patients having ICC with frozen material were selected. In 47 cases, DNA hybridization has been performed on a genomewide SNP array. A procedure with a segmentation step and a calling step classified genomic regions into copy-number aberration states. We identified the exclusively amplified and deleted recurrent genomic areas. These areas are those showing the highest estimated propensity level for copy loss (resp. copy gain) together with the lowest level for copy gain (resp. copy loss). We investigated ICC clustering. We analyzed the relationships between CNAs and clinico-pathological characteristics.

Results

The overall genomic profile of ICC showed many alterations with higher rates for the deletions. Exclusively deleted genomic areas were 1p, 3p and 14q. The main exclusively amplified genomic areas were 1q, 7p, 7q and 8q. Based on the exclusively deleted/amplified genomic areas, a clustering analysis identified three tumors groups: the first group characterized by copy loss of 1p and copy gain of 7p, the second group characterized by 1p and 3p copy losses without 7p copy gain, the last group characterized mainly by very few CNAs. From univariate analyses, the number of tumors, the size of the largest tumor and the stage were significantly associated with shorter time recurrence. We found no relationship between the number of altered cytobands or tumor groups and time to recurrence.

Conclusion

This study describes the spectrum of chromosomal aberrations across the whole genome. Some of the recurrent exclusive CNAs harbor candidate target genes. Despite the absence of correlation between CNAs and clinico-pathological characteristics, the co-occurence of 7p gain and 1p loss in a subgroup of patients may suggest a differential activation of EGFR and its downstream pathways, which may have a potential effect on targeted therapies.

The significance of genetics for cholangiocarcinoma development

Cholangiocarcinoma (CCA) is a rare malignancy of the liver, arising from bile ducts. The incidence is increasing worldwide, but the prognosis has remained dismal and virtually unchanged in the past 30 years. Although several risk factors have been associated with the development of this cancer, none of them are normally identified in most patients. Diagnosis in advanced stages of the disease and limited therapeutic options contribute to poor survival rates. The recent analysis of genetic and epigenetic alterations occurring in CCA has shed new light in the understanding of the molecular mechanisms leading to the malignant transformation of biliary cells. Further studies in this direction may foster new diagnostic, prognostic and therapeutic approaches. This review provides a global overview of recent advances in CCA and describes the most important genetic mutations and epigenetic alterations so far reported in CCA.

Hilar cholangiocarcinoma: diagnosis, treatment options, and management

Hilar cholangiocarcinoma (HC) is a rare disease with a poor prognosis which typically presents in the 6(th) decade of life. Of the 3,000 cases seen annually in the United States, less than one half of these tumors are resectable. A variety of risk factors have been associated with HC, most notably primary sclerosing cholangitis (PSC), biliary stone disease and parasitic liver disease. Patients typically present with abdominal pain, pruritis, weight loss, and jaundice. Computed topography (CT), magnetic resonance imaging (MRI), and ultrasound (US) are used to characterize biliary lesions. Endoscopic retrograde cholangiopancreatography (ERCP) and percutaneous transhepatic cholangiography (PTC) assess local ductal extent of the tumor while allowing for therapeutic biliary drainage. MRCP has demonstrated similar efficacies to PTC and ERCP in identifying anatomic extension of tumors with less complications. Treatment consists of surgery, radiation, chemotherapy and photodynamic therapy. Biliary drainage of the future liver remnant should be performed to decrease bilirubin levels thereby facilitating future liver hypertrophy. Standard therapy consists of surgical margin-negative (R0) resection with extrahepatic bile duct resection, hepatectomy and en bloc lymphadenectomy. Local resection should not be undertaken. Lymph node invasion, tumor grade and negative margins are important prognostic indicators. In instances where curative resection is not possible, liver transplantation has demonstrated acceptable outcomes in highly selected patients. Despite the limited data, chemotherapy is indicated for patients with unresectable tumors and adequate functional status. Five-year survival after surgical resection of HC ranges from 10% to 40% however, recurrence can be as high as 50-70% even after R0 resection. Due to the complexity of this disease, a multi-disciplinary approach with multimodal treatment is recommended for this complex disease.

Current status of immunotherapy for the treatment of biliary tract cancer

Biliary tract cancer (BTC) is one of the most aggressive malignancies. Although various promising regimens of chemotherapeutic and/or molecular targeted agents have been developed, further treatment modalities, including immunotherapies, still remain to be established for refractory patients who are unresponsive to or relapse after currently available therapeutic options for BTC. Recently, several clinical trials of immunotherapies, including peptide-based vaccines and dendritic cell (DC)-based vaccines, have been reported with promising results. Here we summarize the data from phase I or phase II clinical trials of immunotherapies for BTC. In particular, we introduce our novel immunotherapeutic approach called personalized peptide vaccine (PPV), in which HLA-matched peptides were selected and administered based on the pre-existing host immunity before vaccination, for the treatment of advanced BTC. Further clinical trials would be recommended to prove clinical benefits of these novel immunotherapeutic approaches. Recently concomitant treatments, such as chemotherapies and immune checkpoint blockade, have been reported to enhance the therapeutic effects of cancer immunotherapies through multiple coordinated immune mechanisms. Additional therapies in combination with immunotherapies could produce synergistic effects in the treatment of advanced BTC.

Characterization of a novel rat cholangiocarcinoma cell culture model-CGCCA

AIM: To characterize a culture model of rat CCA cells, which were derived from a transplantable TTA-induced CCA and designated as Chang Gung CCA (CGCCA).

METHODS: The CGCCA cells were cultured at in vitro passage 12 times on a culture dish in DMEM medium. To measure the doubling time, 10³ cells were plated in a 96-well plate containing the growth medium. The cells were harvested 4 to 10 d after seeding, and a standard MTT assay was used to measure the growth. The phenotype of CACCA cell and xenograft was determined by immunohistochemical study. We also determine the chromosomal alterations of CGCCA, G-banding and spectral karyotyping studies were performed. The CGCCA cell line was transplanted into the nude mice for examining its tumorigenicity. 2-Deoxy-2-(¹⁸F)fluoro-D-glucose (FDG) autoradiography was also performed to evaluate the FDG uptake of the tumor xenograft.

RESULTS: The doubling time for the CGCCA cell line was 32 h. After transplantation into nude mice, FDG autoradiography showed that the tumors formed at the cell transplantation site had a latency period of 4-6 wk with high FDG uptake excluding necrosis tissue. Moreover, immunohistochemical staining revealed prominent cytoplasmic expression of c-erb-B2, CK19, c-Met, COX-II, EGFR, MUC4, and a negative expression of K-ras. All data confirmed the phenotypic features of the CGCCA cell line coincide with the xenograft mice tumors, indicating cells containing the tumorigenicity of CCA originated from CCA. In addition, karyotypic banding analysis showed that the diploid (2n) cell status combines with ring and giant rod marker chromosomes in these clones; either both types simultaneously appeared or only one type of marker chromosome in a pair appeared in a cell. The major materials contained in the marker chromosome were primarily identified from chromosome 4.

CONCLUSION: The current CGCCA cell line may be used as a non-K-ras effect CCA model and to obtain information and reveal novel pathways for CCA. Further applications regarding tumor markers or therapeutic targeting of CCA should be addressed accordingly.

Knock-in of Oncogenic Kras Does Not Transform Mouse Somatic Cells But Triggers a Transcriptional Response that Classifies Human Cancers

KRAS mutations are present at a high frequency in human cancers. The development of therapies targeting mutated KRAS requires cellular and animal preclinical models. We exploited adeno-associated virus-mediated homologous recombination to insert the Kras G12D allele in the genome of mouse somatic cells. Heterozygous mutant cells displayed a constitutively active Kras protein, marked morphologic changes, increased proliferation and motility but were not transformed. On the contrary, mouse cells in which we overexpressed the corresponding Kras cDNA were readily transformed. The levels of Kras activation in knock-in cells were comparable with those present in human cancer cells carrying the corresponding mutation. Kras-mutated cells were compared with their wild-type counterparts by gene expression profiling, leading to the definition of a "mutated Kras-KI signature" of 345 genes. This signature was capable of classifying mouse and human cancers according to their KRAS mutational status, with an accuracy similar to or better than published Ras signatures. The isogenic cells that we have developed recapitulate the oncogenic activation of KRAS occurring in cancer and represent new models for studying Kras-mediated transformation. Our results have implications for the identification of human tumors in which the oncogenic KRAS transcriptional response is activated and suggest new strategies to build mouse models of tumor progression.

Biliary tract cancers: molecular profiling as a tool for treatment decisions. A literature review

Biliary tract cancer is a quite rare disease; despite recent significant advances in imaging modalities, most of the patients have advanced disease at presentation thus making radical surgery not feasible. Many different chemotherapeutic regimens have been investigated in small uncontrolled studies, with generally disappointing results. We extensively reviewed the literature on this topic trying to give an explanation to chemoresistance in this setting of patients and considering the molecular profiling as a tool for treatment decision. This review is divided in two parts, in the first one we illustrated chemotherapy results and possible mechanisms of resistance. In the second part we analysed the new molecular targets developing an hypothesis about the future therapeutics perspectives.

Cholangiocarcinoma: molecular targeting strategies for chemoprevention and therapy

Cholangiocarcinomas are devastating cancers that are increasing in both their worldwide incidence and mortality rates. The challenges posed by these often lethal biliary tract cancers are daunting, with conventional treatment options being limited and the only hope for long-term survival being that of complete surgical resection of the tumor. Unfortunately, the vast majority of patients with cholangiocarcinoma typically seek treatment with advanced disease, and often these patients are deemed poor candidates for curative surgery. Moreover, conventional chemotherapy and radiation therapy have not been shown to be effective in prolonging long-term survival, and although photodynamic therapy combined with stenting has been reported to be effective as a palliative treatment, it is not curative. Thus, there is a real need to develop novel chemopreventive and adjuvant therapeutic strategies for cholangiocarcinoma based on exploiting select molecular targets that would impact in a significant way on clinical outcome. This review focuses on potential preventive targets in cholangiocarcinogenesis, such as inducible nitric oxide synthase, cyclooxygenase-2, and altered bile acid signaling pathways. In addition, molecular alterations related to dysregulation of cholangiocarcinoma cell growth and survival, aberrant gene expression, invasion and metastasis, and tumor microenvironment are described in the context of various clinical and pathological presentations. Moreover, an emphasis is placed on the importance of critical signaling pathways and postulated interactions, including those of ErbB-2, hepatocyte growth factor/Met, interleukin-6/glycoprotein130, cyclooxygenase-2, vascular endothelial growth factor, transforming growth factor-beta, MUC1 and MUC4, beta-catenin, telomerase, and Fas pathways as potential molecular therapeutic targets in cholangiocarcinoma.

Infrequent microsatellite instability in liver fluke infection-associated intrahepatic cholangiocarcinomas from Thailand

The liver fluke infection-associated intrahepatic cholangiocarcinoma (ICC) is a major liver cancer in Northeast Thailand. The molecular basis of this ICC is poorly understood. To address possible roles of the DNA mismatch repair (MMR) system in ICC carcinogenesis, a fluorescence-labeling PCR/laser scanning technique with high sensitivity was employed to analyze genomic instability in the nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) in 24 fresh and 13 formalin-fixed, paraffin-embedded tissues of ICC and their corresponding normal parts. Microsatellite instability (MSI) was assessed in nDNA, using 12 highly polymorphic loci including 5 Bethesda markers. These loci were mainly related to major MMR genes, hMSH2 and hMLH1. Also 3 (C)n and/or (C)n(A)n repeat instability at 1 noncoding region in the displacement-loop (D-loop) and 2 coding sequences in NADH dehydrogenase subunit 1 and subunit 5 gene in mtDNA were analyzed. MSI was only detected in 1 (2.7%), 6 (16.7%), 1 (2.9%), 1 (2.9%) or 2 (6.3%) out of 37, 36, 35, 35 or 32 cases at BAT-25, D2S123, D3S1611, D11S904 or D17S250, respectively. LOH was found at D3S1298, D3S1561, D5S346 and TP53 in 4 (18.2%) out of 22, 2 (18.2%) out of 11, 6 (33.3%) out of 18 and 3 (12.5%) out of 24 informative cases, respectively. In mtDNA, none except a single case out of the 37 (2.7%) exhibited repeat sequence instability in the D-loop. We conclude that the liver fluke infection-associated ICC in Thailand is classified as low frequency MSI or microsatellite stable type and that DNA MMR system, through hMSH2 and hMLH1 gene mutations, does not play a major role in its carcinogenesis.

Pancreaticobiliary maljunction: pathophysiological and clinical aspects and the impact on biliary carcinogenesis

BACKGROUND

Pancreaticobiliary maljunction (PBM) is frequently associated with congenital choledochal cyst (CCBD), but differs in embryonic cause and clinical features. It is thought to develop as a misarrangement of the embryonic connections in the pancreaticobiliary ductal system, with the terminal bile duct joined to one of the ducts of the ventral pancreas. Clinical aspects are intermittent abdominal pain, relapsing acute pancreatitis, jaundice, cholangitis, and gallbladder cancer. In patients with PBM and CCBD, primary bile duct stones, acute cholangitis, and bile duct cancer are considered to result from cholestasis, regurgitation of pancreatic juice, and reciprocal reflux of bile and pancreatic juice. The mixture of bile and pancreatic juice due to recipocal reflex very likely plays an important role in biliary carcinogenesis.

PATIENTS AND METHODS

We reviewed the pathophysiological and clinical aspects and biliary carcinogenesis in 250 PBM patients (169 with benign hepatobiliary and pancreatic disease, 81 with malignancy).

RESULTS

PBM patients show elevated cellular proliferation activity in the gallbladder epithelia. A number of oncogenes and tumor suppressor genes have been identified and implicated in carcinogenesis, particularly the K- ras oncogene and the p53 suppressor gene. Some K- ras mutations do not appear essential for hyperplasia but may be an early event in carcinogenesis. The p53 mutations are involved in carcinogenesis in the biliary epithelium in PBM patients.

Comparative genomic hybridization analysis of genetic aberrations associated with development and progression of biliary tract carcinomas

BACKGROUND

Little is known about genetic aberrations associated with development and progression of biliary tract carcinomas.

METHODS

To study chromosomal aberrations associated with development and progression of biliary tract carcinomas, the authors used comparative genomic hybridization to examine 50 such carcinomas.

RESULTS

Gains in part or in whole of chromosomes 1q, 8q, and 20q and losses of 5q, 8p, 9p, and 18q were detected frequently in early stage (T1/T2 classification) biliary tract carcinomas (> or = 40% of 19 early stage tumors), and they also were found in advanced stage (T3/T4 classification) tumors. In particular, loss of 9p was the most frequently observed aberration in both early stage (15 of 19; 78%) and advanced stage tumors (21 of 31; 68%). The frequencies of gains of 7p12-p14 (P < 0.003), 7p21-pter (P < 0.007), and 7q31 (P < 0.01) differed significantly between biliary tract carcinoma with and without distant metastasis. Also, gains of 5p and 19q13 and loss of 6q14-q16 were more frequent in tumors with lymph node metastasis than in those without it (P < 0.02).

CONCLUSIONS

It is likely that loss of 9p is one of the genetic aberrations critical for the development of biliary tract carcinoma, whereas gains of 5p, 7p, 7q, and 19q and loss of 6q are considered later events associated with tumor progression and are thought to confer metastatic potential to biliary tract carcinomas.

Cholangiocarcinoma

Despite overall advances in the ability to diagnose and treat patients with cholangiocarcinoma, the prognosis for patients with this malignancy remains poor. Further improvements in the survival of patients with cholangiocarcinoma will come with the early diagnosis of these lesions. New molecular techniques should improve the ability to screen high-risk patients, such as those with primary sclerosing cholangitis, hepatolithiasis, choledochal cysts, and ulcerative colitis. Improvements in imaging will continue, and spiral CT scanning, duplex ultrasonography, MR imaging and, perhaps, PET scans will improve the ability to stage patients with cholangiocarcinoma noninvasively. Complete surgical resection remains the only curative treatment for malignancies of the biliary tract. Aggressive surgical approaches are likely to continue, and the challenge remains in being able to perform these procedures safely in jaundiced and sometimes septic patients. For patients with unresectable lesions, the optimal form of palliation, whether surgical or nonsurgical, remains to be defined. Finally, multicenter, prospective, randomized trials of chemoradiation need to be performed to delineate an effective adjuvant therapy more precisely, and to improve the overall prognosis of patients with cholangiocarcinoma.

K-ras oncogene mutation in cancer and precancerous lesions of the gallbladder

BACKGROUND AND OBJECTIVES

To determine whether K-ras mutation plays any role in the development and progression of gallbladder cancer, or has any clinical or pathological significance in gallbladder cancer patients, we investigated the presence and incidence of this mutation in the normal mucosa, and precancerous and cancerous lesions of the gallbladder.

METHODS

DNA was obtained from normal mucosa, dysplastic mucosa, primary cancer tissues, and metastatic lymph nodes that were identified and microdissected from the paraffin blocks of 20 gallbladder cancer cases. K-ras codon 12 mutations were investigated using a modified two-step polymerase chain reaction and the restriction fragment length polymorphism method, and by direct sequencing with an automated sequencer.

RESULTS

K-ras mutations were detected in the tissues of 10 out of the 20 patients. A mutation was present in the dysplastic epithelium associated with the primary carcinoma in 3 out of 12 specimens, in metastatic carcinoma in 1 out of 5 patients, and in primary carcinoma in 8 out of 20 patients. Mutation was found only once in the dysplastic, noncancerous epithelium, and only once in a metastatic tumor although not detectable in the primary cancer. Direct sequencing showed that the mutations were G to C substitutions (GGT-->CGT) at the first site of codon 12, except in two cases (GGT-->TGT). There were no correlations between K-ras mutations and clinicopathological factors.

CONCLUSIONS

K-ras mutations were detected in half of the gallbladder cancer cases. We suggest that K-ras mutation may play a role in the development of premalignant lesions or early carcinogenesis in some gallbladder cancers. We were unable to find any evidence that K-ras mutation plays any role in tumor progression or metastasis, or that it has any clinicopathological significance.

Aberrations of the K-ras, p53, and APC genes in extrahepatic bile duct cancer

BACKGROUND AND OBJECTIVES

The genetic alterations involved in extrahepatic bile duct (EHBD) cancer are poorly understood. Our aim was to identify aberrations of the K-ras, p53, and APC genes in EHBD cancer.

METHODS

We investigated aberrations of these genes in 52 EHBD cancers using polymerase chain reaction (PCR) single-strand conformation polymorphism analysis, followed by direct sequence determination and a PCR restriction fragment length polymorphism assay.

RESULTS

The K-ras, p53, and APC genes were mutated in 9.6%, 32.7%, and 0% of EHBD cancers, respectively. Loss of heterozygosity at the p53 and APC gene loci was identified in 15.6% and 38.5% of EHBD cancers, respectively.

CONCLUSIONS

Our results suggest that an unknown suppressor gene on 5q other than the APC gene may be responsible for EHBD cancer.

Molecular biology in cytopathology: current applications and future directions

The use of molecular techniques in cytopathology has become an accepted and billable practice for certain applications. Other applications still are in the developmental or experimental stages but may soon be clinically useful. The current study provides a review of these techniques including molecular detection of clonality, in situ hybridization, loss of heterozygosity, and single base mutation detection. A number of new molecular techniques recently have been described that may have a dramatic impact on diagnostic pathology. These techniques, in situ detection of single base mutations and microarray technology, are introduced and discussed in the context of potential applications to cytopathology in the future.

Chromosome 9p21 loss and p16 inactivation in primary sclerosing cholangitis-associated cholangiocarcinoma

BACKGROUND

Cholangiocarcinoma is a frequent complication of primary sclerosing cholangitis and is a leading cause of mortality in patients with this disease. The tumor suppressor gene p16 is commonly inactivated in many neoplasms; however, the role of p16 in the pathogenesis of cholangiocarcinoma is unclear. Therefore, we examined the role of p16 inactivation in the pathogenesis of cholangiocarcinoma associated with primary sclerosing cholangitis.

MATERIALS AND METHODS

Paraffin-embedded sections from 10 patients who developed cholangiocarcinoma in the setting of primary sclerosing cholangitis were examined. Chromosomal loss at 9p21 was determined using microsatellite analysis. Methylation of a CpG island in the promoter region of the p16 gene was determined using methylation-specific polymerase chain reaction. p16 inactivation was also determined using immunohistochemistry.

RESULTS

Allelic loss at chromosome 9p21 was present in 9 of 10 tumors (90%). Methylation of the p16 promoter was present in 2 of the 8 tumors examined (25%). Four of seven tumors (57%) analyzed by immunohistochemistry demonstrated an absence of p16 nuclear staining.

CONCLUSIONS

Loss of chromosome 9p21 and inactivation of the p16 tumor suppressor gene are common events in primary sclerosing cholangitis-associated cholangiocarcinoma and may play a role in the high incidence of cholangiocarcinoma in patients with primary sclerosing cholangitis.

Gene transfer to the rat biliary tract with the HVJ-cationic liposome method

BACKGROUND/AIMS

The ability to transfer foreign genes into the biliary tract would be useful for the treatment of biliary tract diseases, including cancer, cystic fibrosis and other genetic diseases. To introduce a foreign gene precisely into the rat biliary epithelial cells, we developed a new technique, inserting a polyethylene catheter into the common bile duct through the papilla of Vater by use of a fusigenic cationic liposome with hemagglutinating virus of Japan (HVJ-cationic liposome).

METHODS

Transfection efficiency was estimated with the use of FITC-oligonucleotides (FITC-ODNs) and cDNA of beta-galactosidase (pCAG-lacZ).

RESULTS

FITC-ODNs encapsulated in HVJ-cationic liposome were effectively transfected into cell nuclei of human cholangiocellular carcinoma in vitro after a 30-min incubation as compared with the simple application of naked FITC-ODNs. After in vivo injection of FITC-ODNs using the HVJ-cationic liposome method through the papilla of Vater, fluorescence accumulation was observed only in the epithelial cells of the biliary tract, but not in the parenchymal cells of the liver. Beta-galactosidase expression was observed in the biliary epithelial cells 3 days after the transfection of pCAG-lacZ and was also detected at 14 days, but not at 28 days, without obvious cytotoxicity.

CONCLUSIONS

HVJ-cationic liposome-mediated gene transfer to the biliary tract via the papilla of Vater is a minimally-invasive and an effective gene-delivery method for site-specific targeting to the epithelial cells of the biliary tract, which could be applied to the treatment of human biliary tract diseases.

Detection of codon 12 mutation in the K-ras oncogene in pancreatic tumors

Mutations at codons 12, 13, or 61 of the H-ras, K-ras, and N-ras have been detected in human neoplasias by a variety of techniques. Some of these techniques are very sensitive and can detect K-ras mutation in 90% of the cases of pancreatic adenocarcinomas. We analyzed 11 samples of pancreatic adenocarcinoma, three samples of pancreatic mucinous cystadenoma, and two samples without tumors in formalin-fixed paraffin embedded tissue sections. K-ras mutations at codon 12 were detected by a two-step PCR-enriched technique in all the samples of pancreatic adenocarcinoma, but not in cystadenoma or control samples. This technique may be useful for early detection of pancreatic cancer.

Mutated Ras peptides as vaccines in immunotherapy of cancer

Mutations in codon 12 and 13 of K-RAS are frequently found in human cancer, including pancreatic- and colorectal adenocarcinomas. T cell responses specific for individual RAS mutations can be elicited in vitro by stimulation with synthetic peptides and in vivo following vaccination with antigen presenting cells pulsed ex vivo with synthetic peptides. The peptide-responding T cells are capable of responding to intact p21 ras, and can recognise and kill tumour cell lines and isolated tumour cells harbouring the corresponding RAS mutation. The responding cells can be of both CD4+ and CD8+ phenotype, and these T cell subsets recognise nested epitopes within the vaccine peptides. Mutant ras peptides are therefore possibly an important vaccine for specific immunotherapy in patients with pancreatic and colorectal carcinomas, and are currently being tested in vivo together with GM-CSF as an adjuvant in these cancer patients.

Mutations of K-ras but not p53 genes in biliary duct and pancreatic duct carcinomas induced in hamsters by cholecystoduodenostomy with dissection of the common duct followed by N-nitrosobis(2-oxopropyl)amine

An experimental model for the induction of extrahepatic biliary duct carcinomas in hamsters given cholecystoduodenostomy with dissection of the extrahepatic duct at the distal end of the common duct (CDDB) followed by N-nitrosobis(2-oxopropyl)amine (BOP) has been reported [Tajima et al. (1994) Jpn. J. Cancer Res., 85, 780-788]. The CDDB procedure greatly accelerates cell turnover in the biliary epithelium. In the present experiment, mutations of K-ras and p53 genes in the induced lesions were investigated by the reverse transcriptase-polymerase chain reaction-single strand conformation polymorphism (RT-PCR-SSCP) method followed by direct sequencing. Mutations of K-ras, involving a G to A transition in second position of codon 12 of K-ras exon 1, were detected in six out of eight (75%) extrahepatic bile duct carcinomas and six out of eleven (54.5%) pancreatic duct carcinomas. However, no mutations of p53 were observed in either tumor type. The results indicate an association between anomalous pancreaticobiliary junction and development of biliary carcinomas that may be pertinent to the human situation, and indicate that conditions of the model predispose to mutations occurring in K-ras but not p53.

[Palliative therapy of carcinomas of the biliary system]

CARCINOMA OF THE GALLBLADDER: Only patients suffering from advanced disease have symptoms, that is pain, jaundice, weight loss. Mean 5-year survival rate tends to be lower than 5%. Tumors can be resected with negative margins in 15 to 25% of the patients. Obstructive jaundice can be managed with endoscopic biliary stent in 84% of the patients. After radiotherapy tumor regression is observed in 80% of the patients. Their mean survival time is 10 months.

CHOLANGIOCARCINOMAS

More than 90% of the patients present with jaundice. At the time of presentation, 50% of the patients already have metastases to lymph nodes. Mean total survival time of all patients is 12 months. Surgical resection can successfully be performed in 30 to 40% of the patients suffering from proximal cholangiocarcinomas. Distal unresectable tumors are best palliated with an endoscopically placed stent in 97.5% of the patients. Patients having undergone radiotherapy will have a mean survival time of 9 to 12 months. There is a 12% response rate after chemotherapy with single agents and one of 23% after combined regimens. Intraarterial application of chemotherapy results in 44% response rate.

CONCLUSION

Carcinomas of the biliary tract are often diagnosed at advanced inoperable stages. Patients quality of life can be ameliorated by palliative treatment, i.e. biliary stents, radio-, chemotherapy. Mean survival time does normally not exceed 1 year.