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.
College of Pharmacy, Seoul National University, Seoul, Korea.
Abstract
PURPOSE This study examined the roles of nuclear factor erythroid 2-related factor 2 (NRF2) and programmed death ligand 1 (PD-L1) in colon carcinogenesis, underscoring on sex and differences in tumor location.
MATERIALS AND METHODS A total of 378 participants were enrolled from Seoul National University Bundang Hospital: 88 healthy controls (HC), 139 patients with colorectal adenoma (AD), and 151 patients with colorectal cancer (CRC). Quantitative real-time polymerase chain reaction (PCR), methylation-specific PCR, and immunohistochemistry (IHC) were performed utilizing tumor samples from patients and normal mucosa in the HC group.
RESULTS NRF2 mRNA expression was higher in the CRC group than in the HC and AD groups, with decreased NRF2 methylation in the AD and CRC groups. NRF2 protein expression, as evaluated by IHC, increased in the AD and CRC groups relative to that in the HC group. PD-L1 protein expression was remarkably higher in the CRC group than in the HC and AD groups. These patterns were consistent in both males and females. In sex- and CRC location-specific analyses, NRF2 methylation was lower in female than in male patients with CRC. NRF2 protein expression was significantly higher in females, particularly in patients with right-sided CRC. Moreover, females exhibited increased PD-L1 mRNA expression compared to males in the AD group, and PD-L1 mRNA levels were higher in females with right-sided CRC than in those with cancer at other locations.
CONCLUSION Differences in NRF2 and PD-L1 expression indicate site-specific colon carcinogenesis based on sex, particularly in females with right-sided CRC.
Keywords
CarcinogenesisNuclear factor erythroid 2-related factor 2Programmed death ligand 1Sex characteristics
Figures
Fig. 1.Overview of the analysis scheme: The analysis was conducted in three main comparisons: first, by stage of colorectal carcinogenesis; second, by sex within each group; and lastly, by tumor location within the colorectal cancer (CRC) group.Fig. 2.Changes in the nuclear factor erythroid 2–related factor 2 (NRF2)–KEAP1 signaling pathway during colon cancer development. (A) Expression of the NRF2 mRNA in colon tissues of total, males, and females was measured by quantitative real-time polymerase chain reaction analysis. (B, C) Methylation levels of NRF2 (B) and KEAP1 (C) in total, males, and females. (D, E) Immunohistochemical analysis of NRF2 in colon sections in healthy control (HC), colorectal adenoma (AD), and colorectal cancer (CRC) participants. (D) Representative immunohistochemistry (IHC) images for the scores of NRF2-positive cells (×200). Scale bar=100 μm. (E) The scores of NRF2-postive cells in total, males, and females. *p < 0.05, **p < 0.01, ***p < 0.001.Fig. 3.Changes in the programmed death ligand 1 (PD-L1) and programmed cell death receptor-1 (PD-1) during colon cancer development. (A) Expression of the PD-L1 mRNA in colon tissues of total, males, and females was measured by quantitative real-time polymerase chain reaction analysis. (B, C) Immunohistochemical (IHC) analysis of PD-L1 expression in colon sections in healthy control (HC), colorectal adenoma (AD), and colorectal cancer (CRC) participants. (B) Representative immunohistochemistry images for the PD-L1 (×400). Scale bar=50 μm. (C) The combined positive score of PD-L1 in total, males, and females. (D) Expression of the PD-1 mRNA in colon tissues of total, males, and females was measured by quantitative real-time polymerase chain reaction analysis. *p < 0.05 **p < 0.01, ***p < 0.001.Fig. 4.Increase in cyclooxygenase 2 (COX-2) and interleukin-1β (IL-1β) expression during colorectal cancer development in healthy control (HC), colorectal adenoma (AD), and colorectal cancer (CRC) participants. 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. *p < 0.05, **p < 0.01, ***p < 0.001.Fig. 5.Sex-based analyses of nuclear factor erythroid 2–related factor 2 (NRF2), programmed death ligand 1 (PD-L1), and programmed cell death receptor-1 (PD-1) in healthy control (HC), colorectal adenoma (AD), and colorectal cancer (CRC) groups. (A) Methylation levels of NRF2 in colon tissues of males and female within HC, AD, and CRC groups. (B) Immunohistochemical analysis of NRF2 in colon sections of males and female within HC, AD, and CRC groups. The mRNA expression of the PD-L1 (C) and PD-1 (D) in colon tissues of males and female within HC, AD, and CRC groups. (E, F) Sex-dependent expression of NRF2 and PD-L1 based on the CRC location. (E) Immunohistochemical analysis of NRF2 expression based on the location of CRC in male and female groups, with cancer occurring on the right- or left-side. (F) The mRNA expression of PD-L1 based on the location of CRC in male and female groups, with cancer occurring on the right- or left-side. *p < 0.05, **p < 0.01, ***p < 0.001.Fig. 6.Illustrative summary. Female patients with right colon cancer showed a higher nuclear factor erythroid 2–related factor 2 (NRF2) and programmed death ligand 1 (PD-L1) expression than other patients, while females with left colon cancer showed lower NRF2 methylation levels. AD, colorectal adenoma; COX-2, cyclooxygenase 2; CRC, colorectal cancer; HC, healthy control; IHC, immunohistochemistry; IL, interleukin; MSP, methylation-specific polymerase chain reaction; PD-1, programmed cell death receptor-1; qRT-PCR, quantitative real-time polymerase chain reaction.
그림 출처: PubMed Central 공개 논문 (PMC12527625)
Conflict of interest statement
Conflicts of Interest . Conflict of interest relevant to this article was not reported.
