ABCB4/MDR3 gene mutations and cholangiocarcinomas
Authors: David Tougeron, Ginette Fotsing, Veronique Barbu, Michel Beauchant
Journal: Journal of Hepatology (2012)

Multidrug resistance protein 3 (MDR3), also known as ATP-binding cassette subfamily B, member 4 (ABCB4), is predominantly expressed in the liver and is the critical translocator for phospholipids across canalicular membranes of hepatocytes [1van Helvoort A. Smith A.J. Sprong H. Fritzsche I. Schinkel A.H. Borst P. et al.MDR1 P-glycoprotein is a lipid translocase of broad specificity, while MDR3 P-glycoprotein specifically translocates phosphatidylcholine.Cell. 1996; 87: 507-517Abstract Full Text Full Text PDF PubMed Scopus (799) Google Scholar, 2Davit-Spraul A. Gonzales E. Baussan C. Jacquemin E. The spectrum of liver diseases related to ABCB4 gene mutations: pathophysiology and clinical aspects.Semin Liver Dis. 2010; 30: 134-146Crossref PubMed Scopus (174) Google Scholar]. MDR3 mutations are responsible for progressive familial intrahepatic cholestasis type 3 (PFIC3), low phospholipid-associated cholelithiasis (LPAC syndrome) and intrahepatic cholestasis of pregnancy (ICP) [[3]Jacquemin E. Role of multidrug resistance 3 deficiency in pediatric and adult liver disease: one gene for three diseases.Semin Liver Dis. 2001; 21: 551-562Crossref PubMed Scopus (153) Google Scholar]. Cholangiocarcinoma (CCa) is a rare malignant tumour of the biliary tract, characterized by a dramatically poor prognosis usually due to a delayed diagnosis and inefficient non-surgical treatments [[4]Tyson G.L. El-Serag H.B. Risk factors of cholangiocarcinoma.Hepatology. 2011; 54: 173-184Crossref PubMed Scopus (672) Google Scholar]. To our knowledge, up to now no association between CCa and MDR3 mutations has been reported. In this letter to the editor, we report two cases of association between MDR3 gene mutations and CCa in two non-related families. In the first family, patient 1, a 53-year-old man, was investigated for a perihilar tumoral obstruction and treated by right hepatic lobectomy. The pathological examination showed a CCa with one lymph node metastasis. Non-tumoral peripheral tissues showed signs of cholangitis and ductopenia (Fig. 1). After surgery, itching persisted, alkaline phosphatase level was 894 UI/L and MRI showed multiple partial stenosis of the remaining biliary tract. The patient was given ursodeoxycholic acid (UDCA) with a marked decrease in alkaline phosphatase to 258 UI/L. Twenty-six months after surgery, the CCa recurred with peritoneal carcinosis and the patient died 13 months after the diagnosis of CCa recurrence. Patient 2, patient 1's daughter, had a cholecystectomy at 14 years old for symptomatic gallstones. At 23 years old, she presented with jaundice and itching, which resolved spontaneously. A MDR3 familial biliary disease was suspected. The missense variation NM_000443.3: c.1469T>C in exon 13 was found with heterozygous status in the liver tissue of patient 1 and in the blood leucocytes of patient 2. This heterozygous variation leads to NP_000434: p.Ile490Thr at MDR3 protein level. It is a new variant, but according to SIFT software specialized in mutation interpretation, it predicts a non-functional protein. In the second family, a 55-year-old woman (patient 3), was treated by right hepatectomy for a large perihilar CCa. The pathological examination revealed major ductopenia and inflammatory biliary ducts in the non-tumoral peripheral liver tissue. Ten months after the surgery, a recurrence was detected by CT scan and the patient died 31 months after the initial surgery. Patient 4, patient 3's sister, a 38-year-old woman, had a cholecystectomy at 20 years old for gallstones and surgical ablation of residual gallstones in the common bile duct at 24 years old. She also had an ICP during her first pregnancy. A resection of the right liver was decided due to post-operative common bile duct stenosis and intrahepatic gallstones in segments V and VIII. Histological analysis showed biliary duct inflammation and liver fibrosis probably subsequent to chronic cholestasis. After surgery, she still presented with pruritus, elevated liver enzymes (alkaline phosphatase at 300 IU/L) and developed signs of portal hypertension due to liver fibrosis. Due to intrahepatic lithiasis suggesting LPAC syndrome, we carried out research in order to find the MDR3 mutation. A heterozygous missense sequence variation in exon 24, NM_000443.3:c.2932T>C leading to NP_ 000434: pSer978Pro at the MDR3 protein level was found. Using her paraffin-embedded hepatic tissue, we found the same MDR3 variant in her sister (patient 3), at heterozygous status. The mutation has already been encountered in five other families in France. Cholangiocarcinomas represent less than 5% of digestive tumours and commonly identified risk factors are primary sclerosing cholangitis, congenital biliary abnormalities and hepatolithiasis [[5]Cardinale V. Semeraro R. Torrice A. Gatto M. Napoli C. Bragazzi M.C. et al.Intra-hepatic and extra-hepatic cholangiocarcinoma: new insight into epidemiology and risk factors.World J Gastrointest Oncol. 2010; 2: 407-416Crossref PubMed Google Scholar]. Nevertheless, they represent only a minority of CCa cases. Neither genomic mutation nor hereditary predisposition has been found to be associated with the development of CCa. Cases of intrahepatic CCa from pediatric patients affected by the homozygous mutations of BSEP (Bile Salt Export Pomp), the main bile acid transporter in hepatocytes, have been reported [[6]Scheimann A.O. Strautnieks S.S. Knisely A.S. Byrne J.A. Thompson R.J. Finegold M.J. Mutations in bile salt export pump (ABCB11) in two children with progressive familial intrahepatic cholestasis and cholangiocarcinoma.J Pediatr. 2007; 150: 556-559Abstract Full Text Full Text PDF PubMed Scopus (109) Google Scholar]. The CCa mechanisms associated during the process with BSEP and MDR3 mutations are probably the same, but have yet to be satisfactorily explained. It is well-known that inactive MDR3 is responsible for the accumulation of altered bile in hepatocytes and cholangiocytes, thereby causing microscopic forms of liver damage such as inflammation and fibrosis [[7]Trauner M. Fickert P. Halilbasic E. Moustafa T. Lessons from the toxic bile concept for the pathogenesis and treatment of cholestatic liver diseases.Wien Med Wochenschr. 2008; 158: 542-548Crossref PubMed Scopus (95) Google Scholar]. Chronic biliary inflammation can increase cholangiocyte turnover, thereby enhancing the growth of altered cholangiocytes and leading to increased CCa susceptibility [8Wise C. Pilanthananond M. Perry B.F. Alpini G. McNeal M. Glaser S.S. Mechanisms of biliary carcinogenesis and growth.World J Gastroenterol. 2008; 14: 2986-2989Crossref PubMed Scopus (42) Google Scholar, 9Jaiswal M. LaRusso N.F. Burgart L.J. Gores G.J. Inflammatory cytokines induce DNA damage and inhibit DNA repair in cholangiocarcinoma cells by a nitric oxide-dependent mechanism.Cancer Res. 2000; 60: 184-190PubMed Google Scholar]. These case reports suggest a need for prospective follow-up of patients with MDR3 mutations, in order to identify the CCa risk. It would probably also be interesting to look for an MDR3 mutation in young patients with CCa, especially if there exists a familial history of CCa or biliary disease. The authors declared that they do not have anything to disclose regarding funding or conflict of interest with respect to this manuscript. The authors thank Jeffrey Arsham for editing the manuscript. The authors thank Valerie Paradis, Dominique Valla, Jacques Belghiti and Christine Silvain for their contributions to this work.