Fanconi anemia (FA) is a rare bone marrow failure syndrome caused by mutations in DNA repair genes, and the risk of developing Oral Squamous Cell Carcinoma (OSCC) in FA patients is higher than in the normal population and is seen at younger ages. mi-RNAs and proteins associated with signaling pathways such as PI3K and Wnt, which play a role in cancer pathogenesis, are important biomarker candidates for OSCC development. Tumor suppressor miR-9 have been reported that abnormally expressed in many different cancers and OSCC. Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a characterized human oncoprotein that has been studied in the most of human malignancies. Squamous cell cancers frequently develop in FA patients. Therefore, in this study, we aimed to evaluate the salivary miR-9 and serum CIP2A levels of our FA patients who are likely to develop cancer, and to evaluate them in terms of the risk of developing OSCC and compared them with the healthy control group.

Saliva and serum samples were collected from 25 OSHK patients, 24 FA patients and 40 healthy volunteers, and total RNA was isolated from saliva samples and quantitative Real-Time PCR was performed with the miRCURY LNA miRNA PCR Assay (Qiagen, Hilden, Germany). miR-9 saliva levels were normalized and calculated by the Livak Method. ELISA (Bioassay Technology Laboratory, Shanghai, PRC) method was used to measure serum CIP2A levels.

According to our data, salivary miR-9 levels of both OSCC and FA patients were lower than healthy controls (p=0,01 and p=0,017). In OSCC patients, miR-9 level was related to lymph node metastasis (p=0,04). Serum CIP2A levels in OSCC patients and were higher than in healthy controls (p<0,001).

Our findings indicate that miR-9 and CIP2A may be remarkable biomarkers in the development of OSCC. Since FA patients have a high risk of developing OSCC, close follow-up of the physical examination findings of miR-9 and CIP2A levels can be beneficial.