ABSTRACT
Mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) is a common medically intractable epilepsy syndrome. Although pathogenesis of HS still remains highly controversial, genetics may play a role as a predisposing factor. Previous evidence in a Japanese population revealed that the homozygotes for allele T at position -511 of the interleukin (IL)-1ß gene promoter region (IL-1ß-511 T/T) confers susceptibility to the development of HS. However, whether this polymorphism has an effect on IL-1ß levels in MTLEHS patients was not demonstrated. This study aimed to analyze the distribution of this particular polymorphism in a group of Turkish HS patients and correlate the polymorphism with IL-1ß secretion from the lymphocytes, thus revealing a functional role for IL-1ß in the etiopathogenesis of HS. A single base pair polymorphism at position -511 in the promoter region of the IL-1ß gene was analyzed. The spontaneous and 1 ng/mL lipopolysaccharidestimulated production of IL-1ß by peripheral blood mononuclear cells after 4 and 24 h of incubation were measured by ELISA method. The heterozygous type (-511 C/T) was the most common genotype. There was no difference in frequency of allele -511 T between patients and controls. Analysis of IL-1ß levels, genotype and allele distributions showed no significant difference among the groups (P>0.05). Nevertheless, it was seen that patients who carry a T allele at position -511 of the IL-1ß gene had increased IL-1ß levels. T-allele carriage may be important. Only IL-1ß secretion from the lymphocytes has been assessed in this study. Considering the importance of IL-1ß in the etiopathogenesis of HS, further studies are needed to evaluate locally produced IL-1ß levels.
ABSTRACT
BACKGROUND: Despite advances in diagnostic and treatment strategies, head and neck squamous cell cancer (HNSCC) constitutes one of the worst cancer types in terms of prognosis. PTEN is one of the tumour suppressors whose expression and/or activity have been found to be reduced in HNSCC, with rather low rates of mutations within the PTEN gene (6-8%). We reasoned that low expression levels of PTEN might be due to a transcriptional repression governed by an oncogene. Tbx2 and Tbx3, both of which are transcriptional repressors, have been found to be amplified or over-expressed in various cancer types. Thus, we hypothesize that Tbx3 may be over expressed in HNSCC and may repress PTEN, thus leading to cancer formation and/or progression. METHODS: Using immunohistochemistry and quantitative PCR (qPCR), protein and mRNA levels of PTEN and Tbx3 were identified in samples excised from cancerous and adjacent normal tissues from 33 patients who were diagnosed with HNSCC. In addition, HeLa and HEK cell lines were transfected with a Tbx3 expressing plasmid and endogenous PTEN mRNA and protein levels were determined via qPCR and flow cytometry. Transcription assays were performed to demonstrate effects of Tbx3 on PTEN promoter activity. Mann-Whitney, Spearman's Correlation and Wilcoxon signed-rank tests were used to analyze the data. RESULTS: We demonstrate that in HNSCC samples, Tbx3 mRNA levels are increased with respect to their normal tissue counterparts (p<0.001), whereas PTEN mRNA levels are significantly reduced in cancer tissues. Moreover, Tbx3 protein is also increased in HNSCC tissue sections. Over-expression of Tbx3 in HeLa and HEK cell lines causes reduction in endogenous PTEN mRNA and protein levels. In addition, transcription activity assays reveal that Tbx3 is capable of repressing both the basal and induced promoter activity of PTEN. CONCLUSIONS: We show that Tbx3 is up-regulated in tissue samples of HNSCC patients and that Tbx3 represses PTEN transcription. Thus, our data not only reveals a new mechanism that may be important in cancer formation, but also suggests that Tbx3 can be used as a potential biomarker in cancer.
