World J Mens Health. 2026;44(2):322-333.

Differential NRF2 Methylation and PD-1 Expression in Normal Tissues of Colorectal Adenoma and Carcinoma across Sexes.

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제1저자 송진희, 최용훈 · 교신저자 김나영

PMID 40676885 PMC13036248 DOI 10.5534/wjmh.250061 IF 4.3 소화기내과

소속 (3)

Department of Internal Medicine and Research Center for Sex- and Gender-Specific Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
Department of Internal Medicine and Liver Research institute, Seoul National University College of Medicine, Seoul, Korea. nakim49@snu.ac.kr.
College of Pharmacy, Seoul National University, Seoul, Korea.

Abstract

PURPOSE Metachronous cancer following the cure of the primary cancer could be related with the tumor microenvironment. Recently it has been known that nuclear factor erythroid 2-related factor 2 (NRF2), a key transcription factor regulates immune checkpoint expression, including programmed cell death-ligand 1 (PD-L1), a well-known checkpoint molecule. The aim of this study was to investigate the roles of NRF2 and PD-1 in the tumor microenvironment using the normal colon tissue, with a focus on sex-specific differences.

MATERIALS AND METHODS A total of 280 participants were enrolled including 66 healthy controls (HC), 109 patients with colorectal adenoma (AD), and 105 patients with colorectal cancer (CRC). Quantitative real-time polymerase chain reaction (PCR) for NRF2 and PD-1 and methylation-specific PCR for NRF2 were performed with normal mucosal tissue above the 20 cm from anal verge.

RESULTS NRF2 methylation levels were significantly lower in the AD and CRC groups compared to the HC in both sexes. PD-1 mRNA expression was significantly reduced in the AD and CRC groups compared to the HC group. In terms of sex males showed significantly lower PD-1 mRNA levels in the AD and CRC groups, whereas females displayed significantly higher PD-1 expression in the AD group but significantly lower levels in the CRC group. In conclusion there were significant differences in NRF2 methylation and PD-1 expression in the normal mucosal tissue among CRC, AD, and HC groups, suggesting that metachronous lesions might arise from this underlying tumor microenvironment.

CONCLUSIONS Our results suggest that mRNA expressions of NRF2 and PD-L1 in the normal colon tissue may serve as early molecular markers in colorectal carcinogenesis with distinct sex-specific patterns.

Keywords

ColonNF-E2-related factor 2NeoplasmsProgrammed cell death 1 receptorSex factors

Figures

**Fig. 1** Overview of the study group and analysis scheme. (A) Study group. A total of 280 participants were included in the study: 66 healthy controls (26 males and 40 females), 109 patients with adenomas (57 males and 52 females), and 105 patients with colorectal cancer (68 males and 37 females). (B) Analysis scheme. Based on the sequence of colorectal carcinogenesis in normal tissue, the analysis was conducted for the total cohort, as well as separately for males and females.

**Fig. 2** Changes in the expression and methylation of NRF2 in normal tissue during colon cancer development. (A) Expression of the NRF2 mRNA in colon normal tissues of total, males, and females was measured by quantitative real-time polymerase chain reaction (PCR) analysis. (B) Methylation levels of NRF2 in colon normal tissues of total, males, and females were measured by methylation-specific PCR method. Data are expressed as the mean±standard error of the mean. The p-values calculated from the Kruskal–Wallis test is shown in the figure; ^**p<0.01; ^***p<0.001, comparison between two groups (Mann–Whitney U-test). HC: healthy control, AD: colorectal adenoma, CRC: colorectal adenocarcinoma.

**Fig. 3** Changes in the PD-L1 and PD-1 in normal tissue during colon cancer development. Expression of the PD-L1 mRNA (A) and PD-1 mRNA (B) in colon normal tissues of total, males, and females was measured by quantitative real-time polymerase chain reaction analysis. Data are expressed as the mean±standard error of the mean. The p-values calculated from the Kruskal–Wallis test is shown in the figure; ^**p<0.01; ^***p<0.001, comparison between two groups (Mann–Whitney U-test). HC: healthy control, AD: colorectal adenoma, CRC: colorectal adenocarcinoma, PD-L1: programmed cell death-ligand 1, PD-1: programmed cell death receptor-1.

**Fig. 4** Changes in the COX-2 and IL-1β in normal tissue during colon cancer development. Expression of the COX-2 (A) and IL-1β (B) mRNA in colon tissues of total, males, and females was measured by quantitative real-time polymerase chain reaction analysis. Data are expressed as the mean±standard error of the mean. The p-values calculated from the Kruskal–Wallis test is shown in the figure; there are no significant differences in the comparison between the two groups (Mann–Whitney U-test). HC: healthy control, AD: colorectal adenoma, CRC: colorectal adenocarcinoma, COX-2: cyclooxygenase-2, IL-1β: interleukin 1 beta.

그림 출처: PubMed Central 공개 논문 (PMC13036248)

Conflict of interest statement

The authors have nothing to disclose.

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