Upregulation of p16(INK4A) in Peripheral White Blood Cells as a Novel Screening Marker for Colorectal Carcinoma

OBJECTIVE: Screening of colorectal cancer (CRC) is important for the early detection. CRC is relating to aging and immuno-senescence. One such senescent marker is p16(INK4A) expression in immune cells. The objective of the study is to investigate the protein expression of p16(INK4A) in peripheral white blood cells as a screening marker for colorectal cancer. METHODS: A case-control studies were conducted. Cases were patients with colorectal cancer and controls were matched with cases based on age and sex. Peripheral blood was collected from patients and controls and the protein p16(INK4A) was measured with immunofluorescent techniques. The p16(INK4A) levels from cases and controls were evaluated using ROC analysis to be used as a screening marker in CRC patients. Mean fluorescent intensity of p16(INK4A) of cases and controls were analyzed in CD45+, CD3+ or CD14+ cells. The p16(INK4A) levels of cases were also correlated with clinical data. RESULT: Statistically significant increased expression of p16(INK4A) levels were found in cases compared to controls. p16(INK4A) in peripheral immune cells had 78% sensitivity and 71% specificity which can possibly be used as a diagnosis tool for colorectal cancer. P16(INK4A)-positive cell percentage and mean florescent intensity were significantly higher in CD45+ cells, CD3 positive cells and CD14 positive cells. No significant correlation was observed with the clinical data and p16(INK4A) level of CRC patients. CONCLUSION: The significant increase of p16 (INK4A) expression level in peripheral immune cells represents potential for use as a CRC screening marker.