Numerical and structural centrosome aberrations are an early and stable event in the adenoma–carcinoma sequence of colorectal carcinomas

Abstract

Numerical and structural centrosome changes have been described for and linked with genetic instability in solid tumors. Here, we specifically address centrosome aberrations in the adenoma-carcinoma sequence of colorectal cancer by detailed evaluation of gamma-tubulin staining patterns. Formalin-fixed and paraffin-embedded specimens (normal colonic epithelium n=21; low-grade intraepithelial neoplasia n=27, high-grade intraepithelial neoplasia n=16 and invasive adenocarcinomas n=33) were stained by an anti-gamma-tubulin antibody using standard immunofluorescence. Three-dimensional image stacks of the stainings were recorded (Zeiss LSM510 confocal microscope), followed by numerical and structural data analysis (DIAS software package) and statistical evaluation (NCSS-software). The mean centrosome signal per cell differed significantly (P<0.0001) between normal colonic epithelium (0.8775) and each low-grade intraepithelial neoplasia (1.787), high-grade intraepithelial neoplasia (2.259) and invasive carcinomas (2.267). Similarly, both the centrosomes' structural entropy (SE) and minimal spanning tree (MST) differed significantly (P<0.001) between normal (SE=3.956, MST=38.78) and each low- (SE=6.39, MST=26) and high-grade intraepithelial neoplasia (SE=5.75, MST=26.97) and invasive carcinoma (SE=6.86, MST=28.08). Numerical and structural centrosome dysregulation is seen as early as in low-grade dysplastic lesions of the adenoma-carcinoma sequence of colorectal carcinomas and may, as such, play an initial role in the carcinogenic process.