Studies on p53, BAX and Bcl-2 protein expression and microsatellite instability in stage III (UICC) colon cancer treated by adjuvant chemotherapy: major prognostic impact of proapoptotic BAX

We evaluated the expression patterns of proapoptotic BAX, antiapoptotic Bcl-2 and p53, the proposed upstream effector of these molecules, as potential prognostic markers in UICC stage III colon cancer by immunohistochemical staining. To identify high-frequency microsatellite instability (MSI+) individuals, we performed single-strand conformation polymorphism-based analysis for BAT26. A total of 188 patients who had received 5-fluorouracil (5-FU)-based adjuvant chemotherapy (5-FU/folinic acid or 5-FU/levamisole) were enrolled. Median follow-up was 84.5 months. We found that BAX, Bcl-2 and p53 protein expressions were high or positive in 59, 70 and 50% of 188 cases, respectively. MSI+ tumours were detected in 9% of 174 evaluable patients. BAX or Bcl-2 was correlated with a higher degree of differentiation or left-sided tumours (P=0.01 or P=0.03, respectively); MSI was correlated with right-sided tumours (P<0.0001). In contrast to p53, Bcl-2, or MSI, low BAX, advanced pN category, low grade of differentiation and treatment with 5-FU/levamisole were univariately associated with poorer disease-free survival (DFS) (P=0.0005, P=0.001, P=0.005 and P=0.01, respectively) and poorer overall survival (OS) (P=0.002, P=0.0001, P=0.003 and P=0.02, respectively). Besides pN category and treatment arm, BAX was an independent variable related to both OS and DFS (P=0.003 and P=0.001, respectively). In both univariate and multivariate analysis, the p53−/BAX high in comparison with the p53+/BAX high subset conferred a significantly improved DFS (P=0.03 and P=0.03, respectively) as well as a marginally improved OS (P=0.07 and P=0.08, respectively). BAX protein expression may be of central significance for clinical outcome to 5-FU-based adjuvant chemotherapy in stage III colon cancer, and bivariate analysis of p53/BAX possibly may provide further prognostic evidence

Analysis of neuroendocrine differentiation and the p53/BAX pathway in UICC stage III colorectal carcinoma identifies patients with good prognosis

Background and aims Neuroendocrine differentiation is an independent prognostic factor in colorectal cancer. Moreover, an altered p53/BAX pathway is associated with a poor clinical outcome in Union Internationale Contre le Cancer (UICC) stage III disease. Because these markers are involved in different genetic events disrupted in colorectal cancer, we investigated the prognostic power of a multimarker analysis. Patients and methods Specimens were analyzed from 59 patients with UICC stage III disease who underwent surgery for colorectal adenocarcinoma at our institution and were followed up for 5 years or until death. Tumors were studied for both p53 mutation and BAX protein expression as well as for the expression of neuroendocrine markers. Statistical analysis of each marker alone or in combination was performed. Results p53 status/BAX expression and neuroendocrine differentiation are not correlated in stage III colorectal cancers. However, the combination of both independent events identified a subgroup of patients with an excellent prognosis: Patients whose tumors were neuroendocrine marker-negative and who exhibited an intact p53/BAX pathway lived longer (mean survival, 93 months; range, 82–104 months) than patients whose tumors were either neuroendocrine marker-positive or whose tumors had a completely disrupted apoptotic pathway (41 months; range, 26–57 months; p<0.00001). In multivariate regression analysis, neuroendocrine marker-positive, p53 mutated, low-BAX-expressing tumors revealed an almost fivefold higher risk for earlier death (p<0.0001). Conclusion Disruption of the p53/BAX pathway is not pathognomonic for colorectal cancers with neuroendocrine differentiation. Both represent independent prognostic markers in UICC stage III disease. Therefore, the combined analysis of p53 status, BAX expression and neuroendocrine differentiation allows one to identify subgroups of patients with either very good or very poor prognosis

Analysis of p53/BAX in primary colorectal carcinoma: low BAX protein expression is a negative prognostic factor in UICC stage III tumors

Deregulation of cell death pathways contributes to tumor development and to the clinical course of cancer disease. In patients with liver metastases of colorectal cancer, we have previously shown that an intact p53/BAX apoptotic pathway is a positive prognostic factor. Therefore, the purpose of our study was to determine the prognostic value of BAX protein expression and the mutational status of its upstream regulator p53 in primary colorectal adenocarcinoma. To this end, we analyzed retrospectively tumor samples of 116 patients who underwent surgery for colorectal adenocarcinoma and had a follow-up for a minimum of 5 years or until death (UICC Stage III: 59 patients, UICC Stage IV: 57 patients). Tumors were screened for p53 mutations and investigated for BAX protein expression. Overall median survival was 17 months. As expected, patients with UICC III tumors survived longer than patients with UICC IV tumors: 69 months vs. 8 months (p < 0.0001). UICC III tumors with high BAX expression were associated with a significantly better prognosis (p = 0.009) than BAX low expressing tumors. The combined p53/BAX pathway analysis for the UICC Stage III group revealed the worst outcome for patients with a disrupted p53/BAX pathway (i.e., BAX low/p53 mutated; p = 0.004). In contrast, no significant effect of the p53/BAX status on survival was found in UICC IV tumors. Our study in primary adenocarcinoma of the colorectum shows for the first time that a disrupted p53/BAX pathway is associated with a poor clinical outcome in UICC III tumors. These data also confirm our previous report on the relevance of an intact p53/BAX pathway in liver metastasis of colorectal cancer. Nevertheless, we were not able to confirm this finding in the heterogenous subgroup of UICC IV tumors of the colorectum. Our study therefore provides the basis for the analysis of defects in p53/BAX (and additional genes) in a prospective trial that is the logical basis for future risk-adapted therapies

Gene expression profiling reveals two separate mechanisms regulating apoptosis in rectal carcinomas in vivo.

Contains fulltext : 53442.pdf (publisher's version ) (Open Access)The level of apoptosis in rectal carcinomas of patients treated by surgery only predicts local failure; patients with intrinsically high-apoptotic tumors develop less local recurrences than patients with low levels of apoptosis. To identify genes involved in this intrinsic apoptotic process in vivo, 47 rectal tumors with known apoptotic phenotype (24 low- and 23 high-apoptotic) were analyzed by oligonucleotide microarray technology. We identified several genes differentially expressed between low- and high-apoptotic tumors. Unsupervised clustering of the tumors based on expression levels of these genes separated the low-apoptotic from the high-apoptotic tumors, indicating a gene expression-dependent regulation. In addition, this clustering revealed two subgroups of high-apoptotic tumors. One high-apoptotic subgroup showed subtle differences in mRNA and protein expression of the known apoptotic regulators BAX, cIAP2 and ARC compared to the low-apoptotic tumors. The other subgroup of high-apoptotic tumors showed high expression of immune-related genes; predominantly HLA class II and chemokines, but also HLA class I and interferon-inducible genes were highly expressed. Immunohistochemistry revealed HLA-DR expression in epithelial tumor cells in 70% of these high-apoptotic tumors. The expression data suggest that high levels of apoptosis in rectal carcinoma patients can be the result of either slightly altered expression of known pro- and anti-apoptotic genes or high expression of immune-related genes