P53 protein expression in pancreatic tumors and its relationship to clinicopathological factors and prognosis

Meta-analysis of immunohistochemical prognostic markers in resected pancreatic cancer

BACKGROUND

The potential prognostic value of several commonly investigated immunohistochemical markers in resected pancreatic cancer is variably reported. The objective of this study was to conduct a systematic review of literature evaluating p53, p16, smad4, bcl-2, bax, vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) expression as prognostic factors in resected pancreatic adenocarcinoma and to conduct a subsequent meta-analysis to quantify the overall prognostic effect.

METHODS

Relevant literature was identified using Medline, EMBASE and ISI Web of Science. The primary end point was overall survival assessed on univariate analysis. Only studies analysing resected pancreatic adenocarcinoma were eligible for inclusion and the summary log(e) hazard ratio (logHR) and variance were pooled using an inverse variance approach. Evidence of heterogeneity was evaluated using the χ(2) test for heterogeneity and its impact on the meta-analysis was assessed by the I(2) statisic. Hazard ratios greater than one reflect adverse survival associated with positive immunostaining.

RESULTS

Vascular endothelial growth factor emerged as the most potentially informative prognostic marker (11 eligible studies, n=767, HR=1.51 (95% confidence interval, CI=1.18-1.92)) with no evidence of any significant publication bias (Egger's test, P=0.269). Bcl-2 (5 eligible studies, n=314, HR=0.51 (95% CI=0.38-0.68)), bax (5 studies, n=274, HR=0.63 (95% CI=0.48-0.83)) and p16 (3 studies, n=229, HR=0.63 (95% CI=0.43-0.92)) also returned significant overall survival differences, but in smaller patient series due to a lack of evaluable literature. Neither p53 (17 studies, n=925, HR=1.22 (95% CI=0.96-1.56)), smad4 (5 studies, n=540, HR=0.88 (95% CI=0.61-1.27)) nor EGFR (4 studies, n=250, HR=1.35 (95% CI=0.80-2.27)) was found to represent significant prognostic factors when analysing the pooled patient data. There was evidence of significant heterogeneity in four of the seven study groups.

CONCLUSION

These results support the case for immunohistochemical expression of VEGF representing a significant and reproducible marker of adverse prognosis in resected pancreatic cancer.

Molecular prognostic markers in pancreatic cancer

BACKGROUND

Pancreatic cancer is one of the most aggressive human tumors and is virtually incurable. Its incidence in the United States has tripled in the past 50 years. The tumor is a frequent cause of cancer death in both men and women. The current treatment options are inadequate and probably reflect the fact that the etiologic factors and the pathogenesis of pancreatic cancer are unknown.

METHODS

The author reviewed recent studies describing some of the molecular alterations that may play a role in pancreatic carcinogenesis.

RESULTS

Most pancreatic tumors arise in the ductal epithelium. Cytogenetic abnormalities and alterations in proliferation, oncogenes and tumor suppressor genes, cell receptors, and growth factors are described.

CONCLUSIONS

Preliminary studies have implicated, among others, the insulin-like growth factor-1 receptor, Src, and Stat3 proteins in human pancreatic carcinogenesis. These molecules may represent important predictors of tumor behavior and targets of novel therapeutic modalities in human pancreatic cancer.

Bcl-2 expression related to altered p53 protein and its impact on the progression of human pancreatic carcinoma

p53 and Bcl-2 are two important factors related to apoptosis and tumorigenesis. In this study, a series of 52 cases of pancreatic carcinoma (PC) were investigated using an immunohistochemical assay to determine whether altered expression of Bcl-2 and p53 has an impact on the progression of this malignancy. Cytoplasmic immunoreactivity for Bcl-2 and nuclear staining of p53 was found in 12 (23.1%) and 32 (63.5%) cases of PC respectively. Furthermore, an inverse correlation between the expression of p53 and Bcl-2 existed in this series (P < 0.01). In a subgroup, the proportion of tumours showing that p53-positive and Bcl-2-negative staining was increased with increasing histological grade and clinical stage (P < 0.05), and moreover, the survival period of those patients whose tumour had this staining was shorter than those with other staining patterns of combined p53 and Bcl-2 (P < 0.05). Therefore, it is concluded that simultaneously aberrant expression of Bcl-2 and p53 may confer PC with more malignant clinicopathological characteristics.

Role of p53 tumor suppressor gene in pancreatic endocrine tumors of Chinese patients

OBJECTIVE

The molecular genetic of pancreatic endocrine tumor (PET) has rarely been studied in depth because of its rarity. The aim of this study is to determine if there is any implication of p53 overexpression on the pathogenesis and clinicopathological parameters of PET.

METHODS

This study examines the immunohistochemical expression of the p53 gene product in 52 PETs (32 insulinomas, three gastrinomas, two glucagonomas, one carcinoid, and 14 nonfunctional tumors) from Chinese patients (27 men, 25 women) collected over a 23-yr period. Of these, 21% were malignant.

RESULTS

Irrespective of their demographic data, clinical behavior, hormonal status, or pathological features, none of the 52 PETs showed p53 overexpression.

CONCLUSIONS

This observation, together with an analysis of the literature, suggests that p53 gene aberrations may not be important in the pathogenesis of PET.