Increased CK19 expression correlated with pathologic differentiation grade and prognosis in oral squamous cell carcinoma patients.

OBJECTIVE: To investigate cytokeratin 19 (CK19) expression in oral squamous cell carcinoma (OSCC) tissue as well as its correlation with pathologic differentiation grade and prognosis. STUDY
DESIGN: Cancerous and distant tissues from 33 primary OSCC patients were collected during surgery. Each sample was divided into 2 parts, one for CK19 protein detection using immunohistochemistry, and the other for CK19 mRNA-level detection of relative quantification using fluorescent real-time reverse transcriptase polymerase chain reaction (RT-PCR).
RESULTS: The CK19 positive rate in cancerous tissue was 90.9% (30 out of 33) detected using immunohistochemistry, which was significantly higher than that in distant tissue (15.2%, 5 out of 33) by chi-square test (P < .001). The CK19 positive score in cancerous tissue was also significantly higher than that in the corresponding distant tissue by paired samples t test (P < .001). Patients with positive CK19 expression in distant tissue had higher tumor recurrence rate (P = .008) and lower survival rate (P = .015) than those with negative CK19 expression in distant tissue. Using fluorescent real-time RT-PCR, CK19 mRNA level in cancerous tissue was 2.21-fold higher than that in distant tissue (P = .020). The CK19 expression correlated significantly with pathologic differentiation grade, which was detected not only using immunohistochemistry (P = .002) but also using fluorescent real-time RT-PCR (P = .025), poorer differentiated indicating higher CK19 positive score and CK19 mRNA level.
CONCLUSIONS: Increased CK19 protein expression and gene transcription in OSCC tissue correlate significantly with pathologic differentiation grade. Positive CK19 expression in distant tissue suggests a higher tumor recurrence rate and a lower survival rate.