Detection of a novel single nucleotide polymorphism and imprinted status analysis of the Ras protein-specific guanine nucleotide-releasing factor 1 gene in domestic pigs.

The aim of this study was to determine the imprinting status of the Ras protein-specific guanine nucleotide-releasing factor 1 (Rasgrf1) gene in domestic pigs. In this study, a 228-bp partial sequence located in exon 14 and a 193-bp partial sequence located in exon 1 of the Rasgrf1 gene in domestic pigs were obtained. A novel single nucleotide polymorphism, a G/A transition, was identified in Rasgrf1 exon 14, and then the reciprocal Berkshire x Wannan black F1 hybrid model and the reverse transcription-polymerase chain reaction-restriction fragment length polymorphism method were used to detect the imprinting status of the porcine Rasgrf1 gene at the 1-day-old developmental stage. Imprinting analysis showed that, compared to the imprinted expression of the Rasgrf1 gene in mouse and rat, a variable imprinting status was observed in domestic pigs. In principle, the porcine Rasgrf1 gene was maternally expressed in the liver and small intestine, paternally expressed in the lung, and biallelically expressed in brain, heart, spleen, kidney, stomach, pancreas, fat, testis, ovary, longissimus dorsi, and pituitary tissues. In conclusion, our results indicated that the Rasgrf1 gene shows both species- and tissue-specific variation in imprinted expression.

5-Aza-2'-deoxycytidine may influence the proliferation and apoptosis of cervical cancer cells via demethylation in a dose- and time-dependent manner.

The methylation of tumor suppressor genes has been shown to be involved in many human cancers. 5-Aza-2'-deoxycytidine (5-Aza-CdR) can reactivate the expression of methylated tumor suppressor genes. In our study, 2 human cervical cancer cell lines, HeLa and SiHa, were treated with different concentrations (20, 10, 5, and 2.5 µM) of 5-Aza-CdR for 24, 48, and 72 h. After incubation, cells were analyzed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay and flow cytometry. The expression of RASSF1A and APAF-1 was detected by RT-PCR. 5-Aza-CdR inhibited the growth of HeLa and SiHa cells at different concentrations. The strongest inhibition and apoptosis rates were obtained after incubation for 72 h (5.63 ± 1.38 and 8.24 ± 2.40%, respectively). No significant difference in the expression of RASSF1A was found upon drug treatment, while APAF-1 expression increased in HeLa cells after treatment (0.790 ± 0.056%). Our results suggest that the tumor-suppressive effect of 5-Aza-CdR may result from the reactivation of silenced APAF-1 through demethylation.