Significance and Possible Biological Mechanism for CLDN8 Downregulation in Kidney Renal Clear Cell Carcinoma Tissues

Han Chu Ji; Jian Di Li; Guan Lan Zhang; Zhi Guang Huang; Ji Wen Cheng; Sheng Hua Li; Chun Yan Zhao; Yu Xing Tang; Kai Qin; You Liang Ma; Yu Long; Gang Chen; Bin Qin

doi:10.14740/wjon1869

Significance and Possible Biological Mechanism for CLDN8 Downregulation in Kidney Renal Clear Cell Carcinoma Tissues

World J Oncol. 2024 Aug;15(4):662-674. doi: 10.14740/wjon1869. Epub 2024 Jul 5.

Authors

Han Chu Ji^{1

2}, Jian Di Li^{3

2}, Guan Lan Zhang³, Zhi Guang Huang³, Ji Wen Cheng⁴, Sheng Hua Li⁴, Chun Yan Zhao³, Yu Xing Tang³, Kai Qin³, You Liang Ma⁵, Yu Long⁵, Gang Chen³, Bin Qin¹

Affiliations

¹ Department of Urology, Guigang People's Hospital, The Eighth Affiliated of Guangxi Medical University, Guigang 537100, Guangxi Zhuang Autonomous Region, China.
² These authors contributed equally to this article.
³ Department of Pathology, The First Affiliated Hospital of Guangxi Medical University, Nanning 530021, Guangxi Zhuang Autonomous Region, China.
⁴ Department of Urology, The First Affiliated Hospital of Guangxi Medical University, Nanning 530021, Guangxi Zhuang Autonomous Region, China.
⁵ Department of Gynecology and Obstetrics, The First Affiliated Hospital of Guangxi Medical University, Nanning 530021, Guangxi Zhuang Autonomous Region, China.

Abstract

Background: The clinical role of claudin 8 (CLDN8) in kidney renal clear cell carcinoma (KIRC) remains unclarified. Herein, the expression level and potential molecular mechanisms of CLDN8 underlying KIRC were determined.

Methods: High-throughput datasets of KIRC were collected from GEO, ArrayExpress, SRA, and TCGA databases to determine the mRNA expression level of the CLDN8. In-house tissue microarrays and immunochemistry were performed to examine CLDN8 protein expression. A summary receiver operating characteristic curve (SROC) and standardized mean difference (SMD) forest plot were generated using Stata v16.0. Single-cell analysis was conducted to further prove the expression level of CLDN8. A clustered regularly interspaced short palindromic repeats knockout screen analysis was executed to assess the growth impact of CLDN8. Functional enrichment analysis was conducted using the Metascape database. Additionally, single-sample gene set enrichment analysis was implied to explore immune cell infiltration in KIRC.

Results: A total of 17 mRNA datasets comprising 1,060 KIRC samples and 452 non-cancerous control samples were included in this study. Additionally, 105 KIRC and 16 non-KIRC tissues were analyzed using in-house immunohistochemistry. The combined SMD was -5.25 (95% confidence interval (CI): -6.13 to -4.37), and CLDN8 downregulation yielded an SROC area under the curve (AUC) close to 1.00 (95% CI: 0.99 - 1.00). CLDN8 downregulation was also confirmed at the single-cell level. Knocking out CLDN8 stimulated KIRC cell proliferation. Lower CLDN8 expression was correlated with worse overall survival of KIRC patients (hazard ratio of CLDN8 downregulation = 1.69, 95% CI: 1.2 - 2.4). Functional pathways associated with CLDN8 co-expressed genes were centered on carbon metabolism obstruction, with key hub genes ACADM, ACO2, NDUFS1, PDHB, SDHD, SUCLA2, SUCLG1, and SUCLG2.

Conclusions: CLDN8 is downregulated in KIRC and is considered a potential tumor suppressor. CLDN8 deficiency may promote the initiation and progression of KIRC, potentially in conjunction with metabolic dysfunction.

Keywords: CLDN8; Kidney renal clear cell carcinoma; Mechanism; Prognosis; Tissue microarray.

Grants and funding

The study was supported by the Guangxi Higher Education Undergraduate Teaching Reform Project (2022JGA146), Guangxi Educational Science Planning Key Project (2022ZJY2791), Guangxi Medical University Undergraduate Education and Teaching Reform Project (2023Z10), and Guangxi Natural Science Foundation (2021GXNSFAA075033).