To the Editor:

The esophageal squamous cell carcinoma cell lines (KYSE series) have been established and characterized in our laboratory (13). These cell lines have proved to be as useful and appropriate research materials in the field of esophageal squamous cell carcinoma reseacrh. Thus, these cell lines have been provided to many collaborative researchers by us without strict regulation of their use. These cell lines have also been donated to certain cell banks. However, I believe that there is ethical rule that researchers should not use the cell lines and provide them to other researchers without the permission of the originator of the cell lines.

There was a report that some cell lines were already cross-contaminated because of the use of a cell line without strict quality control in the laboratory (4). There may exist a relaxed way of thinking in the usage of the cell lines in these kinds of laboratories.

For these reasons, I read Tong et al.'s article, regarding Aurora-A expression in esophageal squamous cell carcinoma (5), with great interest. I found that there were several mistakes or inappropriate issues in the paper. They stated that they used KYSE-2, 9706, KYSE-450, KYSE-180, Colo-680, KYSE-150, KYSE-140, KYSE-410, KYSE-30, KYSE-510, T12, and KYSE-70 in Materials and Methods without any comment on the source of cell lines. Furthermore, they changed the name Colo-680 and 9706 to KYSE-680 and KYSE-9706, respectively, in the text and figures. Indeed, I established KYSE-30, 70, 140, 150, 180, 410, 450, and 510 cells; however, I have never established KYSE-2, KYSE-680, and KYSE-9706.

Thus, the following questions were raised. Were KYSE-2, KYSE-9706 (or 9706), and KYSE-680 cells established by the authors? If so, the authors should indicate the references for these cells. I think the name of KYSE-2 and KYSE-9706 is unusual. The readers of the journal may misinterpret that these cell lines are included in the KYSE series.

Were these names mislabeled typographic errors? If so, what were the exact names of these cells? Which is correct, the name Colo-680 or KYSE-680? If the name of Colo-680 is correct, was this cell established from esophageal squamous cell carcinoma? The name “Colo” usually represents colon cancer.

I have no record of depositing these cells with the authors. Were KYSE-30, 70, 140, 150, 180, 410, 450, and 510 cell lines obtained from a certain cell bank? If so, they should indicate the exact name of the source bank.

This article has some discrepancies and I am afraid that there may exist cross-contamination of the cells.

In Response:

I fully agree with the comments in Dr. Shimada's letter regarding the respect researchers should have for the originator of cell lines. Similarly, researchers should respect and appreciate all originators who produce and provide materials and agents in our biomedical research. I strongly believe that this is an important issue in our scientific activity.

We appreciate the questions raised by Dr. Shimada regarding KYSE-9706, Colo-680, and KYSE-2 and apologize for typographic errors in the names of these cell lines. Regarding KYSE-9706, most of time in our article, we used the term 9706 instead of KYSE-9706. The exact name of this line is EC9706, which was established by Dr. Mingrong Wang (State Key Laboratory of Molecular Oncology, Beijing, China). This work was published in 2002 (1). In the legend of Fig. 3B, 9706 was mislabeled as KYSE-9706. Regarding Colo-680, the correct name of this cell line is Colo-680N. It is an esophageal squamous cell carcinoma and was established by Dr. G.E. Moore (Colorado Oncology Foundation, Denver, CO). Finally, the correct name of KYSE-2 is YSE-2, derived from a human squamous cell carcinoma (2).


Han Y, Wei F, Xu X, et al. Establishment and comparative genomic hybridization analysis of human esophageal carcinomas cell line EC9706.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi
iHOP [database on internet]. Madrid: Protein Design Group, National Center of Biotechnology 2004. Available from:
Shimada Y, Imamura M, Wagata T, Yamaguchi N, Tobe T. Characterization of twenty one newly established esophageal cancer cell lines.
Kanda Y, Nishiyama Y, Shimada Y, Imamura M, Nomura H, Hiai H. Analysis of gene amplification and over-expression in human esophageal-carcinoma cell lines.
Int J Cancer
Tanaka H, Shibagaki I, Shimada Y, Wagata T, Imamura M, Ishizaki K. Characterization of p53 gene mutations in esophageal squamous cell carcinoma cell lines: Increased frequency and different spectrum of mutations from primary tumors.
Int J Cancer
Helden PD, Wild IJF, Albrecht CF, et al. Cross-contamination of human esophageal squamous cell carcinoma cell lines detected by DNA fingerprint analysis.
Cancer Res
Tong T, Zhong Y, Kong, J et al. Overexpression of Aurora-A contributes to malignant development of human esophageal squamous cell carcinoma.
Clin Cancer Res