Abstract:

Objective   To further illustrate regulation mechanisms on the expression of homeobox gene NKX3.1, the intron and the 10kb upstream region of NKX3.1 gene were cloned and their effects on NKX3.1 promoter activity were determined to find the androgen response element and the tissue-specific enhancer. Methods   According to the sequence of NKX3.1 gene in Genbank, a NKX3.1 promoter-luciferase reporter plasmid was constructed by PCR technology. Further, an intron-promoter-luciferase reporter plasmid and 10 fragments-promoter-luciferase reporter plasmids were constructed separately. After recombinated plasmids were transfected into  prostate cancer cell line LNCaP, the effects of the intron or 10 fragments in the upstream of NKX3.1 gene on the promoter activity were tested by luciferase reporter assay. Androgen response region was analyzed by stimulating LNCaP cells with R1881. Prostate-specific enhancer was analyzed by the transfection of plasmids in different cells. Results   The region between -7681~ -6483bp enhanced the activity of NKX3.1 promoter to 2.6 fold, but it was not tissue-specific. The intron and other 9 fragments could not increase the NKX3.1 promoter activity obviously. R1881 didn’t enhance the activities of intron and 10kb upstream region of  NKX3.1.  Conclusion   The intron and 10 fragments of NKX3.1 gene were not androgen-responsible. A functional positive regulatory element existed from -7681~-6483bp, but it was not tissue-specific.

Key words: Prostate tumor; Human homeobox gene NKX3.1; Gene regulation; Cis-acting element; Androgen-reponse; Tissue-specific