Triiodothyronine (T3) upregulates the expression of proto-oncogene TGFA independent of MAPK/ERK pathway activation in the human breast adenocarcinoma cell line, MCF7

ABSTRACT Objective: To verify the physiological action of triiodothyronine T3 on the expression of transforming growth factor α (TGFA) mRNA in MCF7 cells by inhibition of RNA Polymerase II and the MAPK/ERK pathway Materials and methods: The cell line was treated with T3 at a physiological dose (10−9M) for 10 minutes, 1 and 4 hour (h) in the presence or absence of the inhibitors, α-amanitin (RNA polymerase II inhibitor) and PD98059 (MAPK/ERK pathway inhibitor). TGFA mRNA expression was analyzed by RT-PCR. For data analysis, we used ANOVA, complemented with the Tukey test and Student t-test, with a minimum significance of 5%. Results: T3 increases the expression of TGFA mRNA in MCF7 cells in 4 h of treatment. Inhibition of RNA polymerase II modulates the effect of T3 treatment on the expression of TGFA in MCF7 cells. Activation of the MAPK/ERK pathway is not required for T3 to affect the expression of TGFA mRNA. Conclusion: Treatment with a physiological concentration of T3 after RNA polymerase II inhibition altered the expression of TGFA. Inhibition of the MAPK/ERK pathway after T3 treatment does not interfere with the TGFA gene expression in a breast adenocarcinoma cell line.

TGFA/Taq I polymorphism and environmental factors in non-syndromic oral clefts in Southern Brazil

We report a study of TGFA/ Taq I polymorphisms and environmental factors in non-syndromic oral cleft in Southern Brazil. Nonsyndromic cleft case-parent triads were recruited to participate. Clinical data was collected with an emphasis on tobacco and alcohol use during pregnancy. DNA was extracted from peripheral blood and TGFA/ Taq I polymorphisms were analyzed by PCR/RFLP with Taq I restriction enzyme. Association of clefts and TGFA/ Taq I polymorphisms was determined using a transmission disequilibrium test (TDT). Association of environmental factors, clefts, and genotypes was evaluated with Fisher's exact test. The minor allele frequency was 0.064. We found no evidence of association between TGFA/ Taq I polymorphisms and clefting (TDT p = 0.335). We also found no association between TGFA/ TaqI polymorphisms and environmental factors (alcohol and/or tobacco). Therefore, no evidence was found that TGFA/ Taq I polymorphisms play a role in clefting in this population. No evidence was found that tobacco or alcohol exposure during pregnancy was related to clefting, however a larger sample size is needed to confirm these results.

Lack of promoting effects of phenobarbital at low dose on diethylnitrosamine-induced hepatocarcinogenesis in TGF-alpha transgenic mice.

Phenobarbital (PB), a rodent non-genotoxic carcinogen, showed hormesis, biphasic effects on rat liver carcinogenesis. To test the hypothesis that the hormesis earlier observed for PB induced hepatocarcinogenesis might also exist in the TGF-alpha transgenic mice model, one which is highly susceptible to carcinogenesis, the carcinogenic or promotion effects of a wide range of phenobarbital (PB) concentrations were investigated. Two weeks after a single i.p. dose of 5 mg /kg bw of diethylnitrosamine (DEN) to 15 day old mice, animals were treated with diet containing PB at doses of 0, 2, 15 or 500 ppm. The incidence and multiplicity of tumors, including hepatocellular adenomas and carcinomas, were significantly increased by the high dose of PB, but no significant difference among the groups receiving 2 and 15 ppm for liver tumors when compared to DEN alone group. The proliferating cell nuclear antigen indices for liver tumors and surrounding hepatocytes in high dose PB treated mice were significantly increased, but no change was noted at the lower doses. The total cytochrome P450 content in the liver was also elevated by 500 ppm of PB, while hepatic 8-OHdG levels demonstrated no significant change. In conclusion, PB at high dose enhances DEN-induced hepatocarcinogenesis in TGF-alpha transgenic mice, but low doses lack any significant effects. One possible mechanism of phenobarbital carcinogenicity might be influenced by cytochrome P450 system exhibiting a strong promoting activity for liver of mice.

Estudio de asociación por desequilibrio de ligamiento entre los genes TGFA, RARA, y BCL3 y fisura labiopalatina no sindrómica (FLPNS) en la población chilena / Possible association due to linkage disequilibrium of TGFA, RARA and BCL3 with nonsyndromic cleft lip with or without cleft palate in the Chilean population

Background: Nonsyndromic cleft lip/palate (NSCLP) is a congenital malformation with the characteristics of a complex genetic trait. Based on experimental evidences as well as on association and linkage studies candidate genes TGFA, RARA and BCL3 have been postulated as being involved in the genetic etiology of this pathology. Aim: To test the possible association due to linkage disequilibrium between microsatellite markers located at less than 1cM from the three candidate genes and nonsyndromic cleft lip/palate using the case-parents trio design. Patients and Methods: The sample consisted of 58 case-parents trios. Two microsatellite markers, flanking each one of the candidate genes were analyzed by means of the polymerase chain reaction (PCR) with fluorescent labeled microsatellite markers. Electrophoresis of the PCR products was performed on a laser-fluorescent automatic DNA sequencer. Nonparametric ETDT was used to analyze the genotype data. Results: Significant linkage disequilibrium was detected between D2S443 (TGFA) and NSCLP. Significance was almost reached between D17S800 (RARA) and NSCLP. Alleles 239bp (D2S443) and 172bp (D17S800) showed significant preferential transmission from heterozygous parents to affected offspring. In the case of BCL3 both markers showed no significant results. Conclusions: The results of the present study do not show clear evidence that TGFA or RARA could be involved in the genetic etiology of NSCLP. Even though the importance of retinoic acid in the development of the embryo is well documented the results obtained for RARA are difficult to analyze. In relation to the possible role of BCL3 in NSCLP, recent information postulates that other genes located in the same chromosome region could be involved in NSCLP.