title: Aberrant methylation of the Pleckstrin and Sec7 domain-containing gene             is implicated in ulcerative colitis-associated carcinogenesis through its inhibitory             effect on apoptosis.
abstract: The Pleckstrin and Sec7 domain-containing (PSD) gene, which regulates skeletal rearrangements, has been found to be more frequently methylated both in ulcerative colitis (UC)-associated colorectal cancer tissues (5 of 7; 71.4%) and matched normal epithelia (4 of 7; 57.1%) compared to non-neoplastic UC epithelia (6 of 22; 27.3%) and sporadic colorectal cancer tissues (6 of 32; 18.8%). The levels of PSD mRNA were positively correlated with the methylation status of PSD, as shown by both MSP and bisulfite sequencing. To determine the potential role of PSD silencing in the mechanisms underlying UC-associated carcinogenesis, the levels of senescence, proliferation and apoptosis were evaluated in a normal human fibroblast cell line (NHDF) in which 93% of PSD expression was knocked down by a small-interfering RNA (si-RNA). Although there were no significant differences in the levels of senescence and proliferation caused by PSD knockdown, the level of apoptosis was significantly decreased by PSD knockdown (5.3% in siControl-treated cells vs. 0.67% in siPSD-treated cells, p=0.0001). In addition, reactive oxygen species inducers accelerated apoptosis in NHDF and a neutrophil-like cell line, which was significantly reduced by PSD knockdown. To verify the effect of PSD methylation in tissue sections including 21 samples from UC patients with or without tumors, we elucidated PSD promoting accumulation of filamentous-actin (F-actin) and apoptosis by immunohistochemistry and TUNEL assay, respectively. Both levels of accumulation of F-actin and apoptosis were significantly decreased in specimens from UC patients with PSD methylation compared to those without PSD methylation (F-actin: 0.69±0.86 with vs. 1.57±0.51 without, p=0.0031, apoptotic index: 0.31±0.63 with vs. 1.0±0.88 without, p=0.0277). In conclusion, our results indicate that PSD methylation plays a significant role in the mechanisms underlying UC-associated carcinogenesis through its inhibitory effect on apoptosis in the interaction between colorectal mucosa and neutrophils.
authors: Department of Surgery, Saitama Medical Center, Jichi Medical University, Saitama, Japan.
authors: Shinichiro
authors: S
authors: Okada
authors: Koichi
authors: K
authors: Suzuki
authors: Kato
authors: K
authors: Takaharu
authors: Hiroshi
authors: H
authors: Noda
authors: Hidenori
authors: H
authors: Kamiyama
authors: Takafumi
authors: T
authors: Maeda
authors: Masaaki
authors: M
authors: Saito
authors: Kei
authors: K
authors: Koizumi
authors: Yuichiro
authors: Y
authors: Miyaki
authors: Fumio
authors: F
authors: Konishi
mesh_terms: D000199:Actins / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis / Q000235:genetics*; D048708:Cell Growth Processes / Q000502:physiology; D002460:Cell Line; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D016922:Cellular Senescence / Q000235:genetics; D003093:Colitis, Ulcerative / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D019175:DNA Methylation; D015536:Down-Regulation; D005260:Female; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D055785:Gene Knockdown Techniques / Q000379:methods; D020868:Gene Silencing; D020662:Guanine Nucleotide Exchange Factors; D018922:HL-60 Cells; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D009504:Neutrophils / Q000378:metabolism / Q000473:pathology; D017382:Reactive Oxygen Species / Q000378:metabolism; D055815:Young Adult
chemical_list: D000199:Actins; D020662:Guanine Nucleotide Exchange Factors; D009419:Nerve Tissue Proteins; C109970:PSD protein, human; D017382:Reactive Oxygen Species