A 2021 study that reported an antitumor effect for fucoidan, a sulfated polysaccharide extracted from brown seaweed, in non-small cell lung cancer cells has been retracted, closing the chapter on one of the many papers that have fueled enthusiasm for marine-derived compounds as potential cancer therapies. The retraction notice, published in BMC Complementary Medicine and Therapies, states that the editors lost confidence in the data and conclusions of the article after concerns were raised about the integrity of several figures, and that the authors failed to adequately respond to the concerns when they were raised.
The original paper, published on 11 January 2021, examined the antitumor effect and molecular mechanism of fucoidan in non-small cell lung cancer, the most common category of lung malignancy, which includes adenocarcinomas and squamous cell carcinomas. Fucoidan has attracted sustained attention in the complementary medicine literature because it is a readily available seaweed extract with reported immunomodulatory and anti-proliferative properties, and laboratory studies have repeatedly suggested that it can interfere with signaling pathways that drive cancer cell growth. The retracted study focused on two widely used lung cancer cell lines, A549 and H1650, and reported effects on proteins involved in cell-cycle control and growth signaling.
According to the retraction notice, the problems centered on Figure 2 of the original article, which presented western blot data, a technique in which proteins separated by size are transferred to a membrane and detected with antibodies to reveal whether a target protein is more or less abundant under different experimental conditions. In cancer mechanism studies, western blots are often the decisive evidence that a treatment changed the level of a specific protein, so the authenticity of each band carries substantial weight. The editors identified multiple similarities that should not exist between bands that were supposed to represent different proteins in different experiments.
Specifically, the notice describes a similarity between the Cyclin D1 band in A549 cells shown in Figure 2A and the pm-TOR band in A549 cells shown in Figure 2B. Cyclin D1 is a cell-cycle protein that pushes cells through the G1 phase and is frequently overactive in cancer, while pm-TOR refers to phosphorylated mTOR, the activated form of a central growth-regulating kinase that integrates nutrient and growth-factor signals. A single image cannot legitimately serve as the detection signal for two different proteins probed in two different assays, because each western blot experiment involves separate gel electrophoresis, transfer, antibody incubation, and chemiluminescent detection steps that produce distinct banding patterns.
The editors also documented similarities between panels that were supposed to show results from the two different cell lines treated with the same fucoidan concentrations. The upper part of the A549 panel treated with fucoidan at 10 milligrams per milliliter was found to be similar to the lower part of the H1650 panel at the same concentration, and the lower part of the A549 panel at 16 milligrams per milliliter was similar to the upper part of the corresponding H1650 panel. A549 and H1650 cells are biologically distinct models, derived from different patients and carrying different genetic backgrounds, so their protein expression patterns under identical treatment conditions would be expected to differ. Overlapping image content between such panels suggests that the same underlying image material was reused to represent separate experiments.
The retraction notice records the authors’ responses, which were divided. Authors Xiaohan Chen and Haijun Lu agreed with the retraction, while authors Li Sun, Xiaojuan Wei, Ye Tan, Zhanyi Sun, and Jinju Jiang did not respond to correspondence from the publisher about the retraction. The absence of a coordinated institutional response left the editors with no credible explanation for the duplicated image content, and the notice states plainly that the editors therefore lost confidence in the data and conclusions of the article. The retraction note itself was published on 19 October 2026 as volume 26, article number 310 of the journal, more than five years after the original publication.
The author list of the original paper also reflects a collaboration that bridged clinical and commercial interests. Several authors were affiliated with the Department of Oncology at the Affiliated Hospital of Qingdao University and with Heze Municipal Hospital, while two authors, Zhanyi Sun and Jinju Jiang, were affiliated with the State Key Laboratory of Bioactive Seaweed Substances at Qingdao Brightmoon Seaweed Group Co Ltd, a company operating in the seaweed products industry. Fucoidan research frequently involves such partnerships, because seaweed processors hold both the raw material and the extraction expertise, while clinical departments provide the disease models and the translational motivation. The retraction does not attribute the image problems to any particular affiliation, but the structure of the collaboration illustrates how enthusiasm for a commercially relevant natural product can move a manuscript quickly from the laboratory to publication.
For readers who followed the original findings, the retraction matters because fucoidan has been promoted in some circles as a dietary supplement with anticancer potential, and laboratory papers like this one are often cited in support of such claims. The retracted study reported that fucoidan suppressed lung cancer cell proliferation and modulated the expression of proteins including Cyclin D1 and components of the mTOR pathway, a mechanistic story that fit neatly with the broader narrative that seaweed polysaccharides can restrain the signaling circuits that tumors depend on. With the paper retracted, that specific body of evidence can no longer be relied upon, and citations of it in reviews or meta-analyses should be removed or flagged in accordance with retraction guidelines.
The case also illustrates the technical fingerprints that image-integrity screening has become adept at detecting. Western blot figures are assembled from multiple exposures and panels, and when the same band, or a portion of one, appears in more than one place with different labels, duplication-detection software and attentive readers can identify the overlap even when the images have been flipped, cropped, or adjusted for contrast. In this instance, the reported similarities involved both a within-figure duplication, where one band allegedly represented two different proteins, and cross-panel duplication between the two cell lines, a combination that is difficult to explain as an innocent laboratory error. The failure of most of the author team to engage with the concerns meant that no alternative explanation was ever placed on the record.
The editors’ decision follows the standard logic of research self-correction: when the primary evidence for a conclusion is compromised and the authors cannot or will not defend it, the conclusion must be withdrawn from the scientific record regardless of how plausible it may seem. Retraction does not prove that fucoidan has no antitumor activity, and other independent studies of seaweed-derived compounds continue in laboratories around the world. What it does establish is that this particular dataset, produced with the involvement of a seaweed industry laboratory and published in a complementary medicine journal, cannot support the claims it was published to make. For patients and clinicians weighing marine-derived supplements as part of cancer care, the episode is a reminder that the evidence base for such compounds must be judged study by study, and that retracted papers, however widely they once circulated, no longer count as evidence at all.
Subject of Research: Retraction of a study on the antitumor effect and molecular mechanism of fucoidan in non-small cell lung cancer
Article Title: Retraction Note: Antitumor effect and molecular mechanism of fucoidan in NSCLC
Article References: Chen, X., Sun, L., Wei, X., Lu, H., Tan, Y., Sun, Z., & Jiang, J. (2026). Retraction Note: Antitumor effect and molecular mechanism of fucoidan in NSCLC. BMC Complementary Medicine and Therapies, 26(1), Article 310. https://doi.org/10.1186/s12906-026-05648-0
Image Credits: AI Generated
DOI: 10.1186/s12906-026-05648-0
Keywords: fucoidan, retraction, non-small cell lung cancer, western blot, image duplication, research integrity, Cyclin D1, mTOR, A549, H1650, seaweed extract, BMC Complementary Medicine and Therapies
News Source: Nathaniel Bowman. (October 19, 2026). Seaweed Compound Cancer Study Retracted After Image Duplication Concerns. Scienmag.
