—  HANS POPPER HEPATOPATHOLOGY SOCIETY   —

ErbB-2 and COX-2 as Potential Molecular Targets in Cholangiocarcinoma


Alphonse E. Sirica
Virginia Commonwealth University
Richmond, VA


Supported by National Institutes of Health Grants R01 CA 39225 and R01 CA 83650 to A.E.S.

Cholangiocarcinoma (ChC) is the collective term used to describe cancers arising within the intra- and extrahepatic biliary tract. More than 90% of ChCs are adenocarcinomas, with different histological variants being recognized. ChCs are further classified according to grade as being well, moderately, or poorly differentiated, with the classic diagnosis being well to moderately differentiated ductal adenocarcinoma. Desmoplastic reaction of variable degrees is also a common feature of ChC. While ChCs can occur anywhere within the biliary tract, approximately 40 to 70% occur at the liver hilum at or in close proximity to the bifurcation of the right and left hepatic ducts, whereas 5 to 20% of ChCs develop within liver . The term peripheral ChC is used to describe ChC originating within liver, typically as a solitary or multifocal mass, whereas those tumors originating at the liver hilum are known as hilar, perihilar, or Klaskin tumors.

Macroscopically, intrahepatic ChCs have been further classified as being either:

  1. mass-forming type

  2. periductal infiltrating type

  3. intraductal growth type
with the most commonly encountered types being the desmoplastic infiltrating nodular or diffusely infiltrating varieties [1, 20] [hilar ChCs are typically observed as being sclerosing ductal adenocarcinomas]. The intraductal growth type is the least common and characterized predominantly by intraductal growth with little or no extension beyond the bile duct walls. In comparison, ChCs with a highly infiltrative growth pattern exhibit lymphatic and intrahepatic metastases. Hilar-invasive-type ChCs have been observed to exhibit perineural invasion and nodal involvement more frequently than do peripheral-type tumors. Intraductal papillary neoplasm of the liver exhibiting frequent gastroenteric metaplasia, overproduction of mucin, and progression to intrahepatic mucinous adenocarcinoma has also recently been characterized as forming a spectrum of biliary neoplasms occasionally associated with hepatolithiasis, and which closely resemble intraductal papillary mucinous neoplasm of the pancreas.

Currently, between two and three thousand new cases of ChC occur annually in the USA, and recent epidemiological studies have called attention to the apparent fact that that devastatingly lethal cancer has over the past two to three decades been increasing worldwide in both incidence and mortality , although the cause of these increases remains unclear. Furthermore, the challenges posed by ChC to clinicians and researchers continue to be daunting, due in large part to high morbidity and mortality rates, and the fact that early diagnosis of ChC is difficult, with the majority of patients presenting with advanced disease.

Clinically, treatment options for ChC are limited, and conventional chemotherapy and radiation therapy have to date been notably ineffective in improving long-term survival. Presently, the only hope for long-term survival is complete resection of the tumor. Unfortunately, the vast majority of patients (i.e., 70-90%) presenting with ChC are not good candidates for curative surgery, and in those that have undergone complete surgical resection, the recurrence rate remains quite high . Patients with unresectable ChC have a survival that is generally less than 12 months after diagnosis. In comparison, the five year survival rates of patients in selected series that have undergone curative resection have ranged from 0% to ~ 40%, with 5-year survival rates following resection for ChC complicating primary sclerosing cholangitis (PSC) found to be less than 10%. Photodynamic therapy (PDT) has recently been shown to have a promising effect on improving palliation and survival in patients with unresectable hilar ChC. However, PDT is not curative and further trials are needed to fully assess its effectiveness in combination with biliary stenting as a neoadjuvant therapy for ChC. Lastly, liver transplantation is not generally indicated for ChC, due in large part to the high tumor recurrence rates, although a small selected group of patients with early staged disease have benefited from this procedure.

Based on the fact that ChC remains for the most part a fatal disease with limited treatment options for prolonged survival, together with the fact that this lethal cancer is being encountered more frequently in clinical practice, there is now a real and urgent need to focus on developing novel chemoprevention and therapeutic strategies aimed at exploiting select molecular targets aberrantly expressed during cholangiocarcinogenesis that would hopefully impact in a significant way on clinical outcome.

ErbB-2 and COX-2 as Potential Molecular Therapeutic Targets in ChC
A strong positive correlation has recently been reported between increased plasma membrane ErbB-2 immunostaining intensity and COX-2 immunoreactivity in archival human surgical specimens of ChC of Japanese, Thai, and USA origin and related risk conditions (hepatolithiasis and PSC) compared with normal adult liver. Interestingly, ErbB-2 and COX-2 immunoreactivities were found to be highest in well differentiated ChCs and in the large bile ducts of PSC and hepatolithiasis cases, consistent with the view that ErbB-2 overexpression and COX-2 up-regulation may herald a critical early carcinogenic event in the human hepatobiliary tract. The relationship between ErbB-2 and COX-2 in cholangiocarcinogenesis is further highlighted by the fact that COX-2 mRNA and protein have been shown to be coordinately up-regulated in furan-induced rat ChCs and in a furan tumor-derived ChC cell line (C611B ) constitutively overexpressing tyrosine phosphorylated ErbB-2. In addition, constitutive ErbB-2 signaling has been implicated in the up-regulation of COX-2 in gallbladder epithelium and tumors from transgenic mice overexpressing wild type rat c-erbB-2 under the control of the bovine keratin 5 promoter. More recently, COX-2 was found to be induced in malignant cell transformants of an adult rat cholangiocyte cell line, designated BDE1, following retroviral infection of BDE1 cells in vitro with the rat erbB-2 oncogene.

The selective COX-2 inhibitor celecoxib has recently been reported to induce apoptosis in cultured human and rat ChC cells by a mechanism involving suppression of serine/threonine kinase Akt/PKB (Akt) phosphorylation. Celecoxib was also found to produce a modest but significant inhibition of the tumorous growth of rat C611B ChC cells implanted subcutaneously into syngeneic rats. In addition, emodin, an ErbB-2 inhibitor, has been shown to elicit significant dose-dependent growth inhibition correlated with increased apoptosis in cultures of rat C611B ChC cells overexpressing ErbB-2. Moreover, of particular interest, emodin in combination with celecoxib acted synergistically to significantly suppress anchorage-dependent and -independent growth of C611B ChC cells through a mechanism involving enhanced Akt inactivation and increased activation of caspase-9/-3-mediated apoptosis . Similarly, a dual EGFR/ErbB-2 inhibitor acted synergistically with celecoxib to suppress the growth of cultured HuCCT1 ChC cells.

Preclinical experimental animal experiments are now being conducted to test the effectiveness of select molecular therapeutic and chemopreventive strategies aimed at targeting ErbB family receptor tyrosine kinase receptors alone and in combination with select COX-2 inhibitors as potentially useful adjuvant treatments for ChC. There is no doubt that selective molecular targeting, such as that which may be obtained with select small drug inhibitors, antiisense vectors, small interfering RNA therapeutics against animal models of ChC that recapitulate important cellular and molecular features of the human disease will provide a challenging, but hopefully useful approach for realistically predicting if such novel treatments can be translated into clinical therapies against a cancer for which there is currently only limited treatment options.

Selected References

  1. Sirica AE. Cholangiocarcinoma: chemopreventive and molecular therapeutic targeting strategies. Hepatology 2005; 41: in press.

  2. Sirica AE. Bile duct cancer, ERBB-2, and COX-2. Science & Medicine 2002; 8:268-277.

  3. Gores GJ. Cholangiocarcinoma: current concepts and insights. Hepatology 2003; 37:961-969.

  4. Patel T. Increasing incidence and mortality of primary intrahepatic cholangiocarcinoma in the United States. Hepatology 2001; 33:1353-1357.

  5. Khan SA, Taylor-Robinson SD, Toledano MB, Beck A, Elliott P, Thomas HC. Changing international trends in mortality rates for liver, biliary and pancreatic tumours. J Hepatology 2002; 37:806-813.

  6. Sirica AE, Lai G-H, Zhang Z. Biliary cancer growth factor pathways, cyclo-oxygenase-2 and potential therapeutic strategies. J Gastroenterology and Hepatology 2001; 16:363-372.

  7. Kiguchi K, Carbajal S, Chan K, Beltrán L, Ruffino L, Shen J, Matsumoto T, Yoshimi N, Di Giovanni J. Constitutive expression of ErbB-2 in gallbladder epithelium results in development of adenocarcinoma. Cancer Res 2001; 61:6971-6976.

  8. Sirica AE, Lai G-H, Endo K, Zhang Z, Yoon B. Cyclooxygenase-2 and ERBB-2 in cholangiocarcinoma: potential therapeutic targets. Seminars in Liver Disease 2002; 22:303-313.

  9. Zhang Z, Lai G-H, Sirica AE. Celecoxib-induced apoptosis in rat cholangiocarcinoma cells mediated by Akt inactivation and Bax translocation. Hepatology 2004; 39:1028-1037.

  10. Hayashi N, Yamamoto H, Hiraoka N, Dono K, Ito Y, Okami J, Kondo M, Nagano H, Umeshita K, Sakon M, Matsuura N, Nakamori S, Monden M. Differential expression of cyclooxygenase-2 (COX-2) in human bile duct epithelial cells and bile duct neoplasm. Hepatology 2001; 34:638-650.

  11. Endo K, Yoon B, Pairojkul C, Demetris AJ, Sirica AE. ERBB-2 overexpression and cyclooxygenase-2 up-regulation in human cholangiocarcinoma and risk conditions. Hepatology 2002; 36:439-450..

  12. Brunt EM, Swanson PE. Immunoreactivity for c-erbB-2 oncopeptide in benign and malignant diseases of the liver. Am J Clin Pathol 1992; 97(Suppl 1):S53-S61.

  13. Terada T, Ashida K, Endo K, Horie S, Maeta H, Matsunaga Y, Takashima K, Ohta T, Kitamura Y. c-erbB-2 Protein is expressed in hepatolithiasis and cholangiocarcinoma. Histopathology 1998; 33:325-331.

  14. Aishima S-I, Taguchi K-I, Sugimachi K, Shimada M, Sugimachi K, Tsuneyoshi M. c-erbB-2 and c-Met expression relates to cholangiocarcinogenesis and progression of intrahepatic cholangiocarcinoma. Histopathology 2002; 40:269-278.

  15. Lai G-H, Zhang Z, Sirica AE. Celecoxib acts in a cyclooxygenase-2-independent manner and in synergy with emodin to suppress rat cholangiocarcinoma growth in vitro through a mechanism involving enhanced Akt inactivation and increased activation of caspases-9 and –3. Molecular Cancer Therapeutics 2003; 2:265-271.

  16. Lai G-H, Rozich RA, Hixson DC, Sirica AE. Oncogenic neu transformation of rat cholangiocytes: a novel in vitro model of cholangiocarcinogenesis. Proc Am Assoc Cancer Res 2004; 45:1272 (Abstract).

  17. Radaeva S, Ferreira-Gonzalez A, Sirica AE. Overexpression of C-NEU and C-MET during rat liver cholangiocarcinogenesis: a link between biliary intestinal metaplasia and mucin-producing cholangiocarcinoma. Hepatology 1999; 29:1453-1462.

  18. Lai G-H, Sirica AE. Effect of GW572016 on ERBB-2 signaling, cell growth, and apoptosis in rat biliary cancer cells. FASEB J 2003; 17:A257(Abstract).

  19. Mann M, Sheng H, Shao J, Williams CS, Pisacane PI, Sliwkowski MX, Du Bois RN. Targeting cyclooxygenase 2 and HER-2/neu pathways inhibits colorectal carcinoma growth. Gastroenterology 2001; 120:1713-1719.

  20. Tortora G, Caputo R, Damiano V, Melisi D, Bianco R, Fontanini G, Veneziani BM, De Placido S, Bianco AR, Ciardiello F. Combination of a selective cyclooxygenase-2 inhibitor with epidermal growth factor receptor tyrosine kinase inhibitor ZD1839 and protein kinase A antisense causes cooperative antitumor and antiangiogenic effect. Clinical Cancer Res 2003; 9:1566-1572.