Upregulation of the Wnt co-receptor LRP6 promotes hepatocarcinogenesis and enhances cell invasion
Edmund Kwok-Kwan Tung, Betty Yin-Chi Wong, Tai-On Yau, Irene Oi-Lin Ng, Edmund Kwok-Kwan Tung, Betty Yin-Chi Wong, Tai-On Yau, Irene Oi-Lin Ng
Abstract
Background: Activation of the Wnt/β-catenin signaling pathway plays a crucial role in hepatocellular carcinoma (HCC). Low-density lipoprotein (LDL) receptor-related protein-6 (LRP6) is one of the co-receptors of the Wnt/β-catenin pathway and forms a signaling complex with Wnt ligand and Frizzled receptor to activate downstream signaling. However, the role of LRP6 in hepatocarcinogenesis is unclear. In this study, we examined its expression and roles in human HCC.
Methodology/principal findings: Using real-time quantitative RT-PCR, we found that LRP6 was frequently (45%) overexpressed in human HCCs (P = 0.003). In vitro studies showed that ectopic expression of LRP6 increased the protein level of β-catenin. Moreover, overexpression of the full-length and constitutively active LRP6, respectively, activated the WNT/β-catenin signaling pathway, as shown by the TCF/β-catenin reporter assay. With regard to the effects of LRP6 overexpression in HCC cells, stable overexpression of the constitutively active LRP6 in BEL-7402 HCC cells enhanced cell proliferation, cell migration, and invasion in vitro as well as tumorigenicity in nude mice.
Conclusions/significance: Our findings indicate that overexpression of LRP6 contributes to the hyperactivation of the Wnt/β-catenin signaling pathway in human HCCs and suggest it may play a role in hepatocarcinogenesis.
Conflict of interest statement
Competing Interests: The authors have declared that no competing interests exist.
Figures
References
- Ferlay J, Shin HR, Bray F, Forman D, Mathers C, et al. Estimates of worldwide burden of cancer in 2008: GLOBOCAN 2008. Int J Cancer. 2010;127(12):2893–2917.
- Zender L, Kubicka S. Molecular pathogenesis and targeted therapy of hepatocellular carcinoma. Onkologie. 2008;31:550–555.
- Wong CM, Ng IO. Molecular pathogenesis of hepatocellular carcinoma. Liver Int. 2008;28:160–174.
- Takigawa Y, Brown AM. Wnt signaling in liver cancer. Curr Drug Targets. 2008;9:1013–1024.
- Llovet JM, Bruix J. Molecular targeted therapies in hepatocellular carcinoma. Hepatology. 2008;48:1312–1327.
- Kim YD, Park CH, Kim HS, Choi SK, Rew JS, et al. Genetic alterations of Wnt signaling pathway-associated genes in hepatocellular carcinoma. J Gastroenterol Hepatol. 2008;23:110–118.
- Tommasi S, Pinto R, Pilato B, Paradiso A. Molecular pathways and related target therapies in liver carcinoma. Curr Pharm Des. 2007;13:3279–3287.
- Teufel A, Staib F, Kanzler S, Weinmann A, Schulze-Bergkamen H, et al. Genetics of hepatocellular carcinoma. World J Gastroenterol. 2007;13:2271–2282.
- Clevers H. Wnt/beta-catenin signaling in development and disease. Cell. 2006;127:469–480.
- MacDonald BT, Tamai K, He X. Wnt/beta-catenin signaling: components, mechanisms, and diseases. Dev Cell. 2009;17:9–26.
- Wong CM, Fan ST, Ng IO. beta-Catenin mutation and overexpression in hepatocellular carcinoma: clinicopathologic and prognostic significance. Cancer. 2001;92:136–145.
- Li Y, Lu W, He X, Schwartz AL, Bu G. LRP6 expression promotes cancer cell proliferation and tumorigenesis by altering beta-catenin subcellular distribution. Oncogene. 2004;23:9129–9135.
- Liu CC, Prior J, Piwnica-Worms D, Bu G. LRP6 overexpression defines a class of breast cancer subtype and is a target for therapy. Proc Natl Acad Sci U S A. 2010;107:5136–5141.
- Zhang J, Li Y, Liu Q, Lu W, Bu G. Wnt signaling activation and mammary gland hyperplasia in MMTV-LRP6 transgenic mice: implication for breast cancer tumorigenesis. Oncogene. 2010;29:539–549.
- Brennan K, Gonzalez-Sancho JM, Castelo-Soccio LA, Howe LR, Brown AM. Truncated mutants of the putative Wnt receptor LRP6/Arrow can stabilize beta-catenin independently of Frizzled proteins. Oncogene. 2004;23:4873–4884.
- Hu L, Wen JM, Sham JS, Wang W, Xie D, et al. Establishment of cell lines from a primary hepatocellular carcinoma and its metastatis. Cancer Genet Cytogenet. 2004;148:80–84.
- Chan DW, Chan CY, Yam JW, Ching YP, Ng IO. Prickle-1 negatively regulates Wnt/beta-catenin pathway by promoting Dishevelled ubiquitination/degradation in liver cancer. Gastroenterology. 2006;131:1218–1227.
- Moon RT, Kohn AD, De Ferrari GV, Kaykas A. WNT and beta-catenin signalling: diseases and therapies. Nat Rev Genet. 2004;5:691–701.
- Park JY, Park WS, Nam SW, Kim SY, Lee SH, et al. Mutations of beta-catenin and AXIN I genes are a late event in human hepatocellular carcinogenesis. Liver Int. 2005;25:70–76.
- Ishizaki Y, Ikeda S, Fujimori M, Shimizu Y, Kurihara T, et al. Immunohistochemical analysis and mutational analyses of beta-catenin, Axin family and APC genes in hepatocellular carcinomas. Int J Oncol. 2004;24:1077–1083.
- Devereux TR, Stern MC, Flake GP, Yu MC, Zhang ZQ, et al. CTNNB1 mutations and beta-catenin protein accumulation in human hepatocellular carcinomas associated with high exposure to aflatoxin B1. Mol Carcinog. 2001;31:68–73.
- Satoh S, Daigo Y, Furukawa Y, Kato T, Miwa N, et al. AXIN1 mutations in hepatocellular carcinomas, and growth suppression in cancer cells by virus-mediated transfer of AXIN1. Nat Genet. 2000;24:245–250.
- Huang H, Fujii H, Sankila A, Mahler-Araujo BM, Matsuda M, et al. Beta-catenin mutations are frequent in human hepatocellular carcinomas associated with hepatitis C virus infection. Am J Pathol. 1999;155:1795–1801.
- Hsu HC, Jeng YM, Mao TL, Chu JS, Lai PL, et al. Beta-catenin mutations are associated with a subset of low-stage hepatocellular carcinoma negative for hepatitis B virus and with favorable prognosis. Am J Pathol. 2000;157:763–770.
- Mi K, Johnson GV. Role of the intracellular domains of LRP5 and LRP6 in activating the Wnt canonical pathway. J Cell Biochem. 2005;95:328–338.
- Beagle B, Johnson GV. Differential modulation of TCF/LEF-1 activity by the soluble LRP6-ICD. PLoS ONE. 2010;5:e11821.
- Pinson KI, Brennan J, Monkley S, Avery BJ, Skarnes WC. An LDL-receptor-related protein mediates Wnt signalling in mice. Nature. 2000;407:535–538.
- Tamai K, Semenov M, Kato Y, Spokony R, Liu C, et al. LDL-receptor-related proteins in Wnt signal transduction. Nature. 2000;407:530–535.
- Wehrli M, Dougan ST, Caldwell K, O'Keefe L, Schwartz S, et al. arrow encodes an LDL-receptor-related protein essential for Wingless signalling. Nature. 2000;407:527–530.
- Merle P, Kim M, Herrmann M, Gupte A, Lefrancois L, et al. Oncogenic role of the frizzled-7/beta-catenin pathway in hepatocellular carcinoma. J Hepatol. 2005;43:854–862.
- Merle P, de la Monte S, Kim M, Herrmann M, Tanaka S, et al. Functional consequences of frizzled-7 receptor overexpression in human hepatocellular carcinoma. Gastroenterology. 2004;127:1110–1122.
- Kim M, Lee HC, Tsedensodnom O, Hartley R, Lim YS, et al. Functional interaction between Wnt3 and Frizzled-7 leads to activation of the Wnt/beta-catenin signaling pathway in hepatocellular carcinoma cells. J Hepatol. 2008;48:780–791.
- Bengochea A, de Souza MM, Lefrancois L, Le Roux E, Galy O, et al. Common dysregulation of Wnt/Frizzled receptor elements in human hepatocellular carcinoma. Br J Cancer. 2008;99:143–150.
- Zhang Z, Schittenhelm J, Guo K, Buhring HJ, Trautmann K, et al. Upregulation of frizzled 9 in astrocytomas. Neuropathol Appl Neurobiol. 2006;32:615–624.
- Kirikoshi H, Sekihara H, Katoh M. Expression profiles of 10 members of Frizzled gene family in human gastric cancer. Int J Oncol. 2001;19:767–771.
- Janssens N, Andries L, Janicot M, Perera T, Bakker A. Alteration of frizzled expression in renal cell carcinoma. Tumour Biol. 2004;25:161–171.
- Li Y, Bu G. LRP5/6 in Wnt signaling and tumorigenesis. Future Oncol. 2005;1:673–681.
- Hoang BH, Kubo T, Healey JH, Sowers R, Mazza B, et al. Expression of LDL receptor-related protein 5 (LRP5) as a novel marker for disease progression in high-grade osteosarcoma. Int J Cancer. 2004;109:106–111.
- Guo Y, Rubin EM, Xie J, Zi X, Hoang BH. Dominant negative LRP5 decreases tumorigenicity and metastasis of osteosarcoma in an animal model. Clin Orthop Relat Res. 2008;466:2039–2045.
- Bjorklund P, Svedlund J, Olsson AK, Akerstrom G, Westin G. The internally truncated LRP5 receptor presents a therapeutic target in breast cancer. PLoS ONE. 2009;4:e4243.
- Bjorklund P, Akerstrom G, Westin G. An LRP5 receptor with internal deletion in hyperparathyroid tumors with implications for deregulated WNT/beta-catenin signaling. PLoS Med. 2007;4:e328.
Source: PubMed