Objective: The immunohistochemical expression of 72-kDa metalloproteinase was evaluated in cervical intraepithelial neoplasia (CIN) and microinvasive carcinoma, with the aim to define a relationship between 72-kDa metalloproteinase expression and neoplastic invasiveness, useful to identify subsets of intraepithelial lesions with higher risk of progression.
Materials and methods: Cervical bioptic samples were obtained consecutively from 54 women who attended our Colposcopic Service from January 1993 to July 1993 because of abnormal pap smear, suspicious for cervical dysplasia and/or human papillomavirus infection. After written consent, 29 women with CIN were included in the study. All women with CIN 3 lesion underwent conization; in 21 women with mild or moderate cervical dysplasia, we did not perform any medical or physical treatment but followed them longitudinally at close interval. After 12 months, the clinical evolution was classified as spontaneous remission, persistence, or progression depending on the absence or presence of lesion and/or HPV infection in colposcopy, histology, and polymerase chain reaction findings. In the study we also included surgical specimens from 10 women with microinvasive squamous carcinoma who underwent primary radical surgery. Seventy-two kilodalton metalloproteinase positivity was immunohistochemically stained on serial sections by using the avidin-biotin complex technique (Vector Laboratories, Burlingame, CA) and expressed as percentage of cells per 10(3) counted neoplastic cells.
Results: Cytoplasmatic positive 72-kDa metalloproteinase immunostaining was significantly higher in microinvasive cervical carcinomas than in CIN lesion (Student's t test; P < 0.001). Considering only cervical intraepithelial neoplasias, a significant increase in 72-kDa metalloproteinase immunostaining was observed with CIN degree increasing (one-way analysis of variance; P = 0.002). No correlation was found between 72-kDa metalloproteinase immunostaining and HPV infection and lesion size defined by quadrants of the cervix involved with colposcopically evident dysplasia. By analyzing 72-kDa metalloproteinase positivity, regressive dysplasia showed low values of 72-kDa metalloproteinase immunostaining (median 1.2%, range 0.5-1.8%), while persistent (median 2.6%, range 1.9-3.6%) and progressive lesions (median 4.6%, range 2.3-6.9%) presented a significantly higher positivity (one-way analysis of variance; P < 0.001).
Discussion: In conclusion, the 72-kDa metalloproteinase expression is related to invasive potential with a significant increase in staining positivity in microinvasive carcinomas; 72-kDa metalloproteinase is detectable in cervical dysplasia, and it is related to the severity of cellular atypia. A clinical implication of 72-kDa metalloproteinase immunostaining seems to be indicated, by analyzing the differences in 72-kDa metalloproteinase positivity rates between regressive and persistent or progressive disease.