Objectives To explore the differentially expressed proteins in normal cervix, cervical intraepithelial neoplasia (CIN) and cervical squamous cell carcinoma (CSCC) tissues by differential proteomics technique.

Methods Cervical tissues (including normal cervix, CIN and CSCC) were collected in Department of Gynecologic Oncology of Beijing Obstetrics and Gynecology Hospital. 2-D DIGE) and DeCyder software were used to detect the differentially expressed proteins. MALDI-TOF/TOF MS was used to identify the differentially expressed proteins. WB and IHC were performed to validate the expressions of selected proteins among normal cervix, CIN and CSCC.

Results 46 differentially expressed proteins were differentially expressed among the normal cervix, CIN and CSCC. 26 proteins were successfully identified by MALDI-TOF/TOF MS. S100A9 was the most significantly up-regulated protein. eEF1A1 was the most significantly down-regulated protein. The results of WB showed that with the increase in the severity of cervical lesions, the expression of S100A9 protein was significantly increased among the three groups (P = 0.010). IHC showed that protein S100A9 was mainly expressed in the cytoplasm, and its positive expression rate was 20.0% in normal cervix, 70.0% in CIN and 100.0% in CSCC, with a significant difference among them (P = 0.006).

Conclusions There are differentially expressed proteins among normal cervix, CIN and CSCC. S100A9, eEF1A1 and PKM2 may become candidate markers for early diagnosis of cervical cancer and new targets for therapy. It also provides a basis for further studies of the mechanism for CIN developing to CSCC.