The aim of the study was to assess the expression of MGMT, p16, and APC genes in tumors and matching surgical margin samples from 56 patients with primary OSCC. We also analyzed the association of the clinical variables with the expression of the studied genes. After RNA isolation and cDNA synthesis gene expression levels were assessed by quantitative reverse transcription (qRT)-PCR. Two-sided parametrical Student's t-test for independent groups with equal/unequal variances showed no statistically significant differences in genes' expression in tumor compared to margin samples. No association was found between the genes' expression and clinical parameters, except for MGMT, whose low expression was probably associated with smoking (0.87 vs 1.34, p=0.065). 'Field cancerization' is an area with genetically or epigenetically altered cells and at the same time a risk factor for cancer. Disturbances in gene expression could also be the source of damages leading to cancerization. In conclusion, it is important to mention that the field remaining after a surgery may pose an increased risk of cancer development. It may be suggested that the diagnosis and treatment of cancers should not be concentrated only on the tumor itself, but also on the cancer field effect. Therefore, further molecular analysis on surgical margins and additional research regarding their assessment are required.
Normal human T lymphocytes growing in culture undergo replicative senescence. Previously, we have shown that in our conditions polyclonal T cells cease proliferation after about three weeks (Radziszewska et al., 1999, Cell Biol. Int. 23, 97-103). Now we present results of a more detailed analysis of in vitro growth as well as phenotypic changes of T cells. Cell cycle analysis showed that about 20% of cells were in the S phase untill the 17th day of culture (young cells). The highest number of mitotic cells (phase G2/M; 10%) was observed during the first week of culture. All not dividing senescent cells were stopped in the G1 phase (after the 30th day of culture). The sub-G1 fraction which represents apoptotic cells did not exceed 8% during the whole period until the 30th day of culture. During in vitro T-cell growth, a rather rapid selection to CD3+CD8+ cells occurs. In the presenescent (between the 17th and 30th day) and senescent populations the majority of cells (above 90%) were CD8 positive. We also have checked the expression of α-chain interleukin-2 (IL-2) receptor (CD25). In young and presenescent cells about one third of cells was CD25 positive, but only 15% in the pool of senescent cells. Immunoblotting analysis of p16 protein recognized previously as a marker of senescent T cells, showed its highest and transient expression in presenescent cells. A critical review of the polyclonal T cell replicative senescence model is presented.
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