Research Article Anticancer Effect of Fucoidan in Combination with Tyrosine Kinase Inhibitor Lapatinib Byeongsang Oh, 1,2 Jihun Kim, 1,3 Weidong Lu, 1 and David Rosenthal 1 1 Dana-Faber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA 2 Sydney Medical School, University of Sydney, Sydney, NSW 2006, Australia 3 University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea Correspondence should be addressed to Byeongsang Oh; byeongsang oh@dfci.harvard.edu Received 10 June 2013; Accepted 9 December 2013; Published 22 January 2014 Academic Editor: Mei Tian Copyright © 2014 Byeongsang Oh et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background. Despite a number of in vitro and in vivo studies reporting the efcacy of fucoidan in treating various cancers, few studies have measured the efcacy of dietary fucoidan (DF) in combination with cancer drugs. Tus, we examined the sensitivity of DF in combination with the EGFR/ERBB2-targeting reagent lapatinib on cancer cells. Method. We selected six EGFR/ERBB2-amplifed cancer cell lines (OE19, NCI-N87, OE33, ESO26, MKN7, and BT474) asan in vitro model and tested their sensitivity to DF alone and to DF in combination with the well-known EGFR/ERBB2-targeting reagent lapatinib. Result. Overall, in drug independent sensitivity test, DF alone did not signifcantly inhibit the growth of EGFR/ERBB2-amplifed cancer cells in vitro. When DF was given in combination with lapatinib, however, it tended to synergistically inhibit cell growth in OE33 but antagonized the action of lapatinib in ESO26, NCI-N87, and OE19. Conclusion. Tis study suggests that DF has the potential to increase or decrease the efects of certain anticancer drugs on certain cancer cell types. Further study is needed to explore the mechanism of interaction and synergistic antitumor activity of DF in combination with chemotherapy and targeted therapy. 1. Introduction Te use of dietary supplements (DS) is gaining in global pop- ularity as a form of complementary and alternative medicine (CAM) [1, 2]. DS, defned as any product that contains vit- amins, minerals, herbs or other botanicals, amino acids, enz- ymes, and/or other ingredients intended to supplement diet, is currently one of the most increasingly used CAM therapies [3]. A study found that 69% of the cancer patients in the US use DS following their cancer diagnosis [4]. A recent Aus- tralian survey with cancer patients also reported that approx- imately 69% of respondents had used one form of CAM in the previous year and 41% of them had visited a CAM practi- tioner [5]. Currently, thousands of DS products are available over the counter without health professionals’ prescription, though the majority of DS have yet to be evaluated in clinical trials. Tus, most oncologists are concerned about possible herb-drug interactions that might occur with conventional anticancer drugs resulting in either excess toxicity or reduced efcacy [6]. A few studies have examined the interaction between herbs and chemotherapy drugs, but none have been examined yet to look at targeted agents [6]. And so, study on DS is essential to provide evidence-based information for cancer patients as well as healthcare practitioners. Fucoidan, one kind of DS, has been reported to exhibit anti-infammatory, antibacterial, antiviral, immunomodulat- ing, antiangiogenesis, and antitumor activities [7–10]. Fuc- oidan, a sulfated polysaccharide found in cell walls of various species of brown and green seaweeds, is known to contain lar- ge proportions of L-fucose and sulfate along with low amo- unts of xylose, uronic acid, and galactose [9, 11]. Seaweed and marine algae have been used as food and medicine for over a thousand years in Asia and in some parts of northern Europe [12]. Recently, the antitumor efect of fucoidan has been studied intensively. Studies have reported that the intake of seaweed is associated with a lower incidence of breast cancer [13, 14]. A recent study of patients with unresectable advanced or recurrent colorectal cancer suggests that fucoidan has the potential to reduce the toxicities of chemotherapy [15]. In vivo studies conducted using mouse xenograf models have Hindawi Publishing Corporation Evidence-Based Complementary and Alternative Medicine Volume 2014, Article ID 865375, 6 pages http://dx.doi.org/10.1155/2014/865375