Using an inducible transcription system which allows the regulated expression of C/EBP isoforms in tissue culture cells, we have found that the ectopic expression of C/EBP␣, at a level comparable to that found in normal liver tissue, has a pronounced antimitogenic effect in mouse L cells and NIH 3T3 cells. The inhibition of cell division by C/EBP␣ in mouse cells cannot be reversed by simian virus 40 T antigen, by oncogenic ras, or by adenovirus E1a protein. When expressed in thymidine kinase-deficient L cells or 3T3 cells, C/EBP␣ is detected in a protein complex which binds to the E2F binding sites found in the promoters of the genes for E2F-1 and dihydrofolate reductase (DHFR). Bacterially expressed C/EBP␣ has no affinity for these E2F sites, but when recombinant C/EBP␣ is added to nuclear extracts from mouse fibroblasts, a new E2F binding activity appears, which contains the C/EBP␣ protein. Using an E2F-DP1-responsive promoter linked to a reporter gene, it can be shown that C/EBP␣ directly inhibits the induction of this promoter by E2F-DP1 in transienttransfection assays. Furthermore, C/EBP␣ can be shown to inhibit the S-phase induction of the E2F and DHFR promoters in permanent cell lines. These findings delineate a straightforward mechanism for C/EBP␣-mediated cell growth arrest through repression of E2F-DP-mediated S-phase transcription.

Hepatic metastasis from colorectal cancer (mCRC) is best treated with a multidisciplinary approach. Conflicting data exist regarding the impact of preoperative chemotherapy on morbidity and mortality after hepatectomy. We hypothesized that preoperative chemotherapy does not adversely impact complications or mortality associated with hepatectomy. A retrospective analysis was performed and included patients with mCRC who underwent hepatectomy from 1996 to 2006. Patients were separated into two groups: those who received preoperative chemotherapy and those who did not. Univariate and multivariate analyses were performed to determine the factors associated with morbidity and mortality. Kaplan-Meier analyses were performed to determine disease-free survival (DFS) and overall survival (OS). One hundred eighty-six patients were analyzed: 112 (60%) received preoperative chemotherapy for a median of 4.2 months. Eighty patients (43%) underwent major hepatectomy. When comparing the two groups, there were no differences in hepatic tumor size (median 3 cm; p = 0.35), type of resection (p = 0.62), stage (p = 0.44) or location (p = 0.10) of the primary tumor, preoperative carcinoembryonic antigen (CEA) level (p = 0.80), or number of nodes in lymphadenectomy (p = 0.62). Only number of positive nodes after colectomy (p = 0.02), age (p < or = 0.0001), and combined resection/radiofrequency ablation (RFA) (p = 0.004) were statistically different between the two groups. There was no difference in rates of morbidity (p = 0.81), mortality (p = 0.29), DFS (p = 0.25) or OS (p = 0.30). We conclude that the use of preoperative chemotherapy did not increase the risk of complications or death for patients undergoing hepatectomy for metastatic colorectal cancer. Pre-hepatectomy chemotherapy appears to be safe and is an important part of the multidisciplinary approach for this disease.

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We have developed a method for the rapid extraction of nuclear proteins from cultured cells. The ammonium sulfate method described here extracts larger quantities of proteins that retain DNA binding activity than the modified Dignam method and another popular method used for the extraction of transcription factors. The ammonium sulfate method is rapid and can be used to process a large number of samples for gel shift analysis.