Claudin-6 is a single prognostic marker and functions as a tumor-promoting gene in a subgroup of intestinal type gastric cancer

  • Tomohiro Kohmoto
  • Kiyoshi Masuda
  • Katsutoshi Shoda
  • Rizu Takahashi
  • Sae Ujiro
  • Shoichiro Tange
  • Daisuke Ichikawa
  • Eigo Otsuji
  • Issei ImotoEmail author
Original Article



We aimed to identify novel tumor-promoting drivers highly expressed in gastric cancer (GC) that contribute to worsened prognosis in affected patients.


Genes whose expression was increased and correlated with worse prognosis in GC were screened using datasets from the Cancer Genome Atlas and Gene Expression Omnibus. We examined Claudin-6 (CLDN6) immunoreactivity in GC tissues and the effect of CLDN6 on cellular functions in GC cell lines. The mechanisms underlying GC-promoting function of CLDN6 were also investigated.


CLDN6 was identified as a gene overexpressed in GC tumors as compared with adjacent non-tumorous tissues and whose increased expression was positively correlated with worse overall survival of GC patients, particularly those with Lauren’s intestinal type GC, in data from multiple publicly available datasets. Additionally, membranous CLDN6 immunoreactivity detected in intestinal type GC tumors was correlated with worse overall survival. In CLDN6-expressing GC cells, silencing of CLDN6 inhibited cell proliferation and migration/invasion abilities, possibly via suppressing transcription of YAP1 and its downstream transcriptional targets at least in part.


This study identified CLDN6 as a GC-promoting gene, suggesting that CLDN6 to be a possible single prognostic marker and promising therapeutic target for a subset of GC patients.


Claudin-6 Stomach neoplasms Prognosis Computer simulation Oncogenes 



This study was supported in part by JSPS KAKENHI, grant number JP18H02894 as a Grant-in-Aid for Scientific Research (B) (to I.I.), 18K07910 as a Grant-in-Aid for Scientific Research (C) (to K.M), and 18J21308 as a Grant-in-Aid for JSPS Research Fellow (to T.K.). We thank Hideaki Horikawa and Akiko Watanabe (Support Center for Advanced Medical Sciences, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan) for their technical assistances.

Author contributions

All of the listed authors contributed to the current study. II conceived and designed the experiments; TK and KM performed the experiments; TK, KM, KS, ST, and II analyzed the data; KS, DI, and EO performed collection of the tissue specimens; and TK, KM, and II wrote the paper. All authors have read and approved the final version of the manuscript.

Compliance with ethical standards

Conflict of interest

None of the authors have conflicts of interest to declare.

Ethics approval

All procedures were performed in accordance with the ethical standards of the responsible committees on human experimentation (institutional and national), as well as the Helsinki Declaration of 1964 and later versions, and approved by the ethics committee of Kyoto Prefectural University of Medicine.

Informed consent

Informed consent or an acceptable substitute was obtained from all patients prior to inclusion in the study.

Consent for publication

Consent to publish the present findings was obtained from all of the participants.

Supplementary material

10120_2019_1014_MOESM1_ESM.pdf (117 kb)
Fig. S1. Outline of strategy used to identify candidate GC-promoting genes with systematic bioinformatic analysis.. Fig. S2. (a) Kaplan–Meier curves for OS rates of 231 GC patients whose Lauren classification data were available from TCGA database. The patients were classified into the intestinal and diffuse groups according to the Lauren criteria. A log-rank test was used for statistical analysis. (b) Kaplan–Meier curves for OS rates of 573 GC patients with Lauren classification data available from the GEO datasets. The patients were classified into the intestinal and diffuse groups according to the Lauren criteria. A log-rank test was used for statistical analysis. (c) Kaplan–Meier curves for OS rates of 208 GC patients from the KPUM cohort. The patients were classified into the intestinal and diffuse groups according to the Lauren criteria. A log-rank test was used for statistical analysis. Fig. S3. (a) Histogram of CLDN6 mRNA expression for GC patients from GEO datasets. The cutoff point to discriminate patients with CLDN6-high from those with CLDN6-low GC tumors was determined using a minimum P value model obtained from log-rank test results of 633 GC samples (normalized signal intensity = 5.10). (b) Kaplan–Meier curves for OS rates of 633 GC patients classified into CLDN6-high and -low expression groups according to values using the method described in Fig. S3a. (c) Kaplan–Meier curves for OS rates of 633 GC patients classified into intestinal type with CLDN6-high, intestinal type with CLDN6-low, diffuse type with CLDN6-high, and diffuse type with CLDN6-low groups. The cutoff value for discriminating patients with CLDN6-high from those with CLDN6-low GC tumors was determined using the method described in Fig. S3a. Fig. S4. Relationship between CLDN6 and YAP1 mRNA expression for GC patients from TCGA (a) and GEO (b) data sets. The horizontal and vertical red dotted lines indicate median of YAP1 and CLDN6 mRNA expression, respectively. Modified histograms of CLDN6 mRNA expression for GC patients from TCGA (Fig. 1b) and GEO (Fig. S3a) data sets are shown below the scatter plots. (PDF 118 kb)
10120_2019_1014_MOESM2_ESM.pdf (61 kb)
Supplementary file2 (PDF 61 kb)


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Copyright information

© The International Gastric Cancer Association and The Japanese Gastric Cancer Association 2019

Authors and Affiliations

  1. 1.Department of Human Genetics, Graduate School of Biomedical SciencesTokushima UniversityTokushimaJapan
  2. 2.Division of Molecular GeneticsAichi Cancer Center Research InstituteNagoyaJapan
  3. 3.Kawasaki Medical SchoolKurashikiJapan
  4. 4.Division of Digestive Surgery, Department of SurgeryKyoto Prefectural University of MedicineKyotoJapan
  5. 5.First Department of Surgery, Faculty of MedicineUniversity of YamanashiChuoJapan
  6. 6.Department of Cancer GeneticsNagoya University Graduate School of MedicineNagoyaJapan

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