OCT4 promotes tumorigenesis and inhibits apoptosis of cervical cancer cells by miR-125b/BAK1 pathway.

Octamer-binding transcription factor 4 (OCT4) is a key regulatory gene that maintains the pluripotency and self-renewal properties of embryonic stem cells. Although there is emerging evidence that it can function as oncogene in several cancers, the role in mediating cervical cancer remains unexplored. Here we found that OCT4 protein expression showed a pattern of gradual increase from normal cervix to cervical carcinoma in situ and then to invasive cervical cancer. Overexpression of OCT4 in two types of cervical cancer cells promotes the carcinogenesis, and inhibits cancer cell apoptosis. OCT4 induces upregulation of miR-125b through directly binding to the promoter of miR-125b-1 confirmed by chromatin immunoprecipitation analysis. MiRNA-125b overexpression suppressed apoptosis and expression of BAK1 protein. In contrast, miR-125b sponge impaired the anti-apoptotic effect of OCT4, along with the upregulated expression of BAK1. Significantly, Luciferase assay showed that the activity of the wild-type BAK1 3'-untranslated region reporter was suppressed and this suppression was diminished when the miR-125b response element was mutated or deleted. In addition, we observed negative correlation between levels of BAK1 and OCT4, and positive between OCT4 and miR-125b in primary cervical cancers. These findings suggest an undescribed regulatory pathway in cervical cancer, by which OCT4 directly induces expression of miR-125b, which inhibits its direct target BAK1, leading to suppression of cervical cancer cell apoptosis.

[Influence of fluoride varnish of different concentration on microhardness of enamel surface]

Varnish is a new type oral material which develops rapidly in recently years,It have had extensive study abroad.It is one of the topical application of fluoride,among them,fluoride-sodium varnish have more significant effect on prevention of dental caries.This study observed the changes of microhardness of cramels after applying fluorid-sodium varnish of different concentration to enamel surfaces.Enamels were randomly parted into three groups,A.B and C.Before fluoride application,the microhardness of enamels were detected,and no significant difference were found among three groups,After that,0.5%,1.5%,2.7% fluoride-sodium varnish were daubed respectively on the three groups enamel surfaces for 24h.The microhardness of enamels were detected again.The results showed all the microhardness of enamels have significant increase statistically after applying fluoride-sodium varnish of different concentration.But,for 0.5% fluorid-Sodium varnish,the increase of microhardness of enamels was only one half of the other two group,which suggested in some concentration range,the fluoride concentration increased one time,the microhardness of enamels increased about one time, but the increase of microhardness of enamels was not synchronized with the increase of fluoride concentration.The increase of microhardness of enamels is almost the same between the two high concentration fluoride-sodium varnish groups,and there in no significant difference statistically.That is when some fluoride concentration were reached,the microhardness of enamels won't increase any more.By the experiment,the writer suggests 1.5% fluorid-sodium varnish is the best on prevention of dental caries.