Immunohistochemical evaluation of ProEx C in human papillomavirus-induced lesions of the cervix

Aims: Considering the sparse information about the clinical utility of the novel immunohistochemical marker ProEx C in histological sections, a decision was taken to study the pattern of ProEx C expression in normal/benign cervical epithelium (N/B), low-grade squamous intraepithelial lesion (LGSIL) and high-grade squamous intraepithelial lesion (HGSIL), as well as the association of ProEx C expression with human papillomavirus (HPV) genotypes. Methods: 100 cervical samples, including 21 N/B cervices, 16 LGSILs, 61 HGSILs and two cervical invasive carcinomas, were obtained from conisation and hysterectomy. Surgical specimens were arranged in three tissue microarrays and stained for ProEx C. Ninety-three samples were HPV genotyped. Genotyping was performed by DNA amplification and hybridisation with genotype-specific probes on a low-density DNA array. Results: ProEx C-positive expression in more than the lower third of the epithelium was observed in 14.3% of N/B, 62.5% of LGSIL and 90.2% of HGSIL. Seventy percent of HPV positivity was found in cases with expression in more than the lower third of the epithelium. Of 31 cases that were positive for HPV16, 16.1% showed ProEx C expression restricted to one or two basal layers, and 83.9% showed ProEx C expression in more than the lower third of the epithelium. Conclusions: ProEx C is significantly associated with HPV16 infection and is a useful adjunct in the identification of LGSIL and HGSIL in histological sections when expressed in more than the lower third of the epithelium.