Open Access

Aberrant methylation of PSD disturbs Rac1-mediated immune responses governing neutrophil chemotaxis and apoptosis in ulcerative colitis-associated carcinogenesis

  • Authors:
    • Takaharu Kato
    • Koichi Suzuki
    • Shinichiro Okada
    • Hidenori Kamiyama
    • Takafumi Maeda
    • Masaaki Saito
    • Kei Koizumi
    • Yuichiro Miyaki
    • Fumio Konishi
  • View Affiliations

  • Published online on: December 15, 2011     https://doi.org/10.3892/ijo.2011.1301
  • Pages: 942-950
  • Copyright: © Kato et al. This is an open access article distributed under the terms of Creative Commons Attribution License [CC BY_NC 3.0].

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Abstract

We previously reported that the Pleckstrin and Sec7 domain-containing (PSD) gene is preferentially methylated in patients with ulcerative colitis (UC) who developed colorectal cancer (CRC), and is implicated in UC-associated carcinogenesis through its inhibition of apoptosis. This study aimed to determine the potential effect of PSD methylation on its downstream molecule, Ras-related C3 botulinum toxin substrate 1 (Rac1), which governs neutrophil chemotaxis and apoptosis signaling. PSD was knocked down in a normal human fibroblast cell line (HNDF) and a neutrophil-like cell line (HL-60). Both NHDF and HL-60 cells exhibited numerous filamentous-actin (F-actin) rich membrane extensions, resulting in the activation of Rac1; this activation was hampered by PSD silencing. Lipopolysaccharide, a reactive oxygen species (ROS) inducer, stimulated NHDF cells to release ROS and activated caspase‑3/7 in the presence of neutrophils, which was inhibited by PSD knockdown. Migration assays demonstrated that chemotaxis of HL-60 cells was affected by PSD silencing in NHDF cells. Tissue sections from 6 UC patients with CRC and 15 UC patients without CRC were examined. To verify Rac1-mediated chemotaxis in tissue sections, we evaluated the grade of neutrophil infiltration by histological assessment and assessed F-actin and PSD expression by immunohistochemistry. Neutrophil infiltration, F-actin and PSD expression were significantly decreased in specimens from UC patients with PSD methylation compared with those without. Decreased levels of F-actin expression were observed in colorectal mucosa, as well as in infiltrating cells with PSD methylation. PSD expression was preferentially inhibited in colorectal mucosa by PSD methylation, whereas PSD expression was rarely observed in infiltrating cells, regardless of PSD methylation status. These data indicate that aberrant methylation of PSD occurs in UC-associated colorectal mucosa, enabling circumvention of Rac1-mediated immune responses governing neutrophil chemotaxis and apoptosis, and thus plays a pivotal role in the mechanisms underlying UC-associated carcinogenesis.
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April 2012
Volume 40 Issue 4

Print ISSN: 1019-6439
Online ISSN:1791-2423

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Spandidos Publications style
Kato T, Suzuki K, Okada S, Kamiyama H, Maeda T, Saito M, Koizumi K, Miyaki Y and Konishi F: Aberrant methylation of PSD disturbs Rac1-mediated immune responses governing neutrophil chemotaxis and apoptosis in ulcerative colitis-associated carcinogenesis. Int J Oncol 40: 942-950, 2012
APA
Kato, T., Suzuki, K., Okada, S., Kamiyama, H., Maeda, T., Saito, M. ... Konishi, F. (2012). Aberrant methylation of PSD disturbs Rac1-mediated immune responses governing neutrophil chemotaxis and apoptosis in ulcerative colitis-associated carcinogenesis. International Journal of Oncology, 40, 942-950. https://doi.org/10.3892/ijo.2011.1301
MLA
Kato, T., Suzuki, K., Okada, S., Kamiyama, H., Maeda, T., Saito, M., Koizumi, K., Miyaki, Y., Konishi, F."Aberrant methylation of PSD disturbs Rac1-mediated immune responses governing neutrophil chemotaxis and apoptosis in ulcerative colitis-associated carcinogenesis". International Journal of Oncology 40.4 (2012): 942-950.
Chicago
Kato, T., Suzuki, K., Okada, S., Kamiyama, H., Maeda, T., Saito, M., Koizumi, K., Miyaki, Y., Konishi, F."Aberrant methylation of PSD disturbs Rac1-mediated immune responses governing neutrophil chemotaxis and apoptosis in ulcerative colitis-associated carcinogenesis". International Journal of Oncology 40, no. 4 (2012): 942-950. https://doi.org/10.3892/ijo.2011.1301