Clinical significance of p16 protein expression loss and aberrant p53 protein expression in pancreatic cancer

Abstract

Pancreatic cancer is a disease with poor prognosis mainly due to low resection rates and late diagnosis. To increase resectability and improve survival rates, a better understanding of pancreatic cancer pathogenesis and more effective screening techniques are required. New methods, such as genetic and molecular alterations, may suggest novel approaches for pancreatic cancer diagnosis and treatment. We immunohistochemically investigated 44 formalin-fixed, paraffin-embedded specimens of pancreatic ductal adenocarcinoma using monoclonal anti-p16 antibodies and monoclonal anti-p53 antibodies. The expressions of p16 and p53 proteins were compared using the Chi-square test with SPSS. Disease-free survival was analyzed using the Kaplan-Meier method, verified by the Log- Rank test. Loss of p16 expression was noted in 20 (45.5%) cases and aberrant p53 protein expression was detected in 14 (31.8%) cases. Loss of p16 expression was associated with a higher incidence of lymph node metastasis (p=0.040) and a more advanced stage (p=0.015), although there was no significant correlation between p16 expression and survival. Aberrant p53 protein expression correlated with histologic grade (p= 0.038). Disease-free survival rate was significantly lower in the aberrant p53 protein positive group compared to the negative group (p=0.029). From our results, we suggest that p53 is not a prognostic factor; however, p16 and p53 genes do play important roles in the progression of pancreatic ductal adenocarcinoma.

Fig. 1

Results of immunohistochemical staining of p16 and p53. Loss of p16 expression was noted in 20 (45.5%) patients and overexpression of aberrant p53 protein was noted in 14 (31.8%) patients.

Fig. 2

Positive immunohistochemical staining for p16 protein and aberrant p53 protein. (A) p16 protein expression in pancreatic ductal adenocarcinoma. (B) aberrant p53 protein expression in pancreatic ductal adenocarcinoma (A and B, LSAB ×200).

Fig. 3

Disease-free survival of patients with pancreatic ductal adenocarcinoma according to p16 protein expression.

Fig. 4

Disease-free survival of patients with pancreatic ductal adenocarcinoma according to aberrant p53 protein expression.