Piwil2 expressed in various stages of cervical neoplasia is a potential complementary marker for p16^ink4a

Generally, cancers may undergo the developmental stages of benign proliferation, precancer and invasive cancer. Identification of biomarkers that are expressed throughout the developmental stages will facilitate detection, prevention and therapy of cancer. Piwil2, a member of AGO/PIWI family of proteins, has been suggested to be associated with tumor development. Here we reported that piwil2 can be detected by immunohistochemistry (IHC) in various stages of human cervical squamous cell carcinomas and adenocarcinomas. Interestingly, piwil2 was also detected in some metaplastic epithelial cells as well as histologically "normal" appearing tissues adjacent to malignant lesions. While all the premalignant and malignant lesions expressed varying levels of piwil2, p16INK4a (p16), a surrogate indicator of high-risk human papillomavirus (HR-HPV) infection, was detected in only 84.62% of the specimens. In Papanicolaou (Pap) test, piwil2 was also detected in atypical glandular cells (AGC), low-grade (LSIL) and high-grade squamous intraepithelial lesions (HSIL), whereas p16 was not always concomitantly detected in the same specimens. The results suggest that piwil2 might play important roles throughout the process of cervical cancer development and have the potential to be used as a complementary marker for p16INK4a. It is worth further study to improve the sensitivity and specificity of current screening methods for cervical cancers.