Effect of formaldehyde and resveratrol on the viability of Vero, HepG2 and MCF-7 cells.

A non-transformed (Vero) and two tumor cell lines (HepG2 and MCF-7) were treated with 10nM to 100 microM formaldehyde. Lower doses (10nM to 10 microM) enhanced the viability of the cultured cells, measured by MTT assay. Higher doses (75-100 microM) decreased viability of the cells by 50% or more. The 100 microM concentration of HCHO has been chosen for combination treatment of the three cell lines with a series of concentrations (0.2-100 microM) of resveratrol, a phytoestrogen occurring in various fruits. Resveratrol decreased the cytotoxicity of formaldehyde depending on cell line and point of time, especially in case of MCF-7 cells at 24 and 72 h, Vero cells at 24h and HepG2 cells at 48 h after treatment. Possible modes of interactions are discussed, considering the role of resveratrol in formaldehyde metabolism and also the estrogen receptor positivity of MCF-7 cells.

Alterations of K-ras and p53 mutations in colorectal cancer patients in Central Europe.

Many molecular investigations of colorectal cancer (CRC) have suggested that the accumulation of specific mutations in proto-oncogenes and tumor suppressor genes regulating cell growth via signal transduction trigger the stagewise progression to malignancy. In this study, the frequency, location, and type of mutations of the K-ras proto-oncogene exon I and p53 tumor suppressor gene exons 5-8 were analyzed in colorectal carcinomas of 65 patients from Central Europe, using polymerase chain reaction (PCR)-cold single-strand conformation polymorphism (SSCP) screening and direct sequencing. The incidence of K-ras activating mutations in these Central European samples was lower (25%) compared to that obtained in American and western European populations (40-50% at least), while the incidence of p53 inactivating mutations was similar (58%). These results suggest that some other genetically linked mechanisms may play a role in CRC development and progression, and hence K-ras and p53 mutations cannot be considered to be universal genetic markers for CRC.

p53 mutations in hairy cell leukemia.

We have studied the frequency of p53 mutations in genomic DNA extracted from peripheral blood or the spleen of 61 patients with hairy cell leukemia using PCR-SSCP and automated cycle sequencing. We identified exon 5-8 mutations in 17 cases, corresponding to a frequency of 28%. In four cases, mutations were localized in exon 5; one patient with atypical HCL had a mutation in exon 6 at the 3' boundary; five cases showed mutations in exon 7, while exon 8 was found to be mutated in seven cases. The mutations found could be divided into three major categories: structural (n=9), inactivating (n= 6), and neutral (n= 2) mutations. None of the three transitions found occurred at CpG dinucleotides. The rate of p53 mutations found in this large cohort of HCL patients is unexpectedly high as in other non-Hodgkin lymphomas p53 mutations predict for poor treatment outcome. The character of the mutations we have found is entirely different from that described in other hematologic malignancies.

Accumulating mutations of p53 in colon tumor and hairy cell leukemia do not arise from methylation/deamination processes, but rather from nucleotide deletions and insertions.

Mutations of the p53 gene may alter the specific regulatory domains of the protein. We examined the conserved domains III, IV and V by SSCP using PCR primers covering exons 5, 6, 7 and 8 from hairy cell leukemia (HCL), polyps, colorectal and gastric carcinomas. A low rate of p53 mutations was detected in HCL and polyps. These mutations may predict the risk of malignant development. However, multiple mutations were a frequent occurrence in tumors. Sequence analysis of our samples did not demonstrate the high frequency of transition mutations (C-->T) that would be predicted if the major course of p53 mutations is deamination of 5-methylcytosine (5mC). Rather, most mutations were found to be single base insertions or deletions.