PHLDA1 expression in ulcerative colitis: A potential role in the management of dysplasia

Pleckstrin homology-like domain, family A, member 1 (PHLDA1) is a protein involved in cell proliferation, adhesion and migration in colon cancer. In normal large intestinal mucosa, this protein is expressed only in the crypts. By contrast, its expression in adenomas and cancers of the large intestine is spread throughout the glandular ducts, and it has been reported that PHLDA1 may be involved in the process of carcinogenesis. PHLDA1 may also be involved in the pathogenesis of ulcerative colitis (UC). The expression levels of PHLDA1 in tissues from patients with UC were analyzed using immunohistochemistry, and its relationship with the development of UC-associated colorectal cancer (UC-CRC) was examined. Overall, tissue samples from 143 lesions (90 colitis lesions, 39 dysplastic lesions and 14 UC-CRC lesions) were prepared from excised specimens of 49 patients with UC who underwent surgery in Tokyo Medical and Dental University Hospital between January 2004 and December 2017. Subsequently, immunostaining for PHLDA1 was performed. PHLDA1 expression was evaluated in UC-CRC and dysplastic tissues within the entire lesion area on the slide and in colitis over the area of the accompanying duct. The cytoplasmic staining intensity was classified into four levels, and the expression score (0-2 points) was calculated. The median PHLDA1 expression score was 0.295 for colitis, 0.607 for dysplasia and 0.865 for UC-CRC. The dysplasia expression score was significantly higher than the colitis score (P<0.001), while the UC-CRC expression score was significantly higher than the dysplasia score (P=0.003). The expression levels of PHLDA1 in UC cases were higher in colitis, followed by dysplasia and UC-CRC, which suggested that this protein may be involved in the carcinogenesis of UC-CRC. In addition, PHLDA1 immunostaining may help in the diagnosis of dysplasia, which is a type of precancerous lesion.