Immunohistochemical evaluation of insulin-like growth factor I receptor status in cervical cancer specimens

The insulin-like growth factor I receptor (IGF-IR) is exceptionally overexpressed in many cervical-cancer-derived cell lines. It is postulated that a decrease of p53 protein levels due to human papillomavirus (HPV) infection may contribute to the up-regulation of IGF-IR expression in cervical cancer cells because transcription of IGF-IR is strictly down-regulated by p53. To evaluate this fact in clinical cervical cancer specimens, we checked the expression levels and activated status of IGF-IR by immunohistochemistry. Formalin-fixed and paraffin-embedded specimens obtained by conization or hysterectomy were stained with anti-IGF-IR and with an antibody recognizing phosphorylated tyrosine at its c-terminus. The expression levels of IGF-IR were significantly high in cervical intraepithelial neoplasia (CIN) III and invasive cancer specimens. Phosphorylation of IGF-IR was promoted in all CIN and invasive cancer specimens, and its intensity was related to the promotion of lesions. Interestingly, IGF-IR overexpression was missing in the basal layer of CIN I and II lesions, whereas it was evenly distributed in CIN III and invasive cancer lesions. This IGF-IR overexpression pattern may be utilized in the diagnosis of HPV infection status in CIN lesions.