p53 mutation in patients with ulcerative colitis in rectal biopsy

Area of Science:

• Gastroenterology
• Molecular Oncology
• Cancer Genetics

Background:

• Long-standing ulcerative colitis (UC) is a known risk factor for colorectal cancer.
• While p53 alterations are observed in dysplasia and carcinoma, their role in early UC-associated changes was unclear.
• Previous studies reported p53 allele loss and aneuploidy in UC-related cancers.

Purpose of the Study:

• To investigate p53 gene mutations in UC patients with and without visible dysplasia.
• To determine if p53 alterations are an early molecular event in UC carcinogenesis.
• To correlate p53 mutations with clinical data and treatment response.

Main Methods:

• Endoscopic rectal mucosal biopsies from 16 UC patients.
• PCR-SSCP analysis of p53 exons 4-8 to detect gene mutations.
• Immunohistochemical staining for p53 protein expression.

Main Results:

• p53 point mutations were found in 4 out of 16 patients (25%), including those with normal-appearing mucosa.
• Two patients with dysplasia and two with non-dysplastic mucosa showed p53 mutations.
• All patients with p53 mutations were positive for p53 protein expression and showed poor response to treatment.

Conclusions:

• p53 gene mutation may represent an early molecular event in the progression of ulcerative colitis to colorectal cancer.
• The presence of p53 mutations in non-dysplastic tissue suggests their role in early carcinogenesis.
• p53 alterations in UC might predict a poorer response to medical therapy.