The Experimental Research About Vitamin D On The Process Of Malignant Transformation Of Human Bronchial Epithelial Cells

Objectives:To study the role of vitamin D during malignant transformation ofimmortalized human bronchial epithelial cells (BEP-2D) induced bytobacco-specific nitrosamine(NNK).Methods:BEP-2D cells were induced for malignantly transformation with500mg/L NNK, and the process was also intervened with the vitaminD.The experiment cells were divided into simplex NNK induction group,low-dose vitamin D intervention group,high-dose vitamin D interventiongroup, alcohol control group and blank control group.The serum resistancein5thpassage of cells, the anchorage independent growth in15thpassage ofcells and the oncogenicity on nude mice in25thpassage of cells wereobserved, The mRNA and protein expression of BMP-2and COX-2weredetected by RT-PCR and Western-Blot, The protein expression of BMP-2and COX-2in the tumor xenogroft on nude mice was detected by immunohistochemistry.Results:（1）Compare with the blank control group, the serum resistance ofvitamin D intervention group and the simplex NNK induction group wasenhanced significantly in the5thpassage, The anchorage independentgrowth appeared in the15thpassage of the vitamin D intervention group andthe simplex NNK induction group, The25thpassage of the vitamin Dintervention group and the simplex NNK induction group cells developedinto tumors in nude mice, So the model of malignantly transformation ofBEP-2D induced by NNK was established.（2）Compare with the simplex NNK induction group, the serumresistance in the5thpassage, the anchorage independent growth(cloningefficiency of soft agar cloning) in the15thpassage and The oncogenicityon nude mice in the25thpassage of the vitamin D intervention groupwas reduced significantly（P<0.05）.（3）Compare with the simplex NNK induction group, themRNAandprotein expression of BMP-2and COX-2of the vitamin D interventiongroup in the25th passage reduced significantly（P<0.05）.（4）Compare with the simplex NNK induction group, the proteinexpression of BMP-2in the tumor xenogroft on mice of the vitamin Dintervention group was decreased significantly（P<0.05）,but there was nosignificant difference of COX-2expression in tumor xenogroft on mice between the simplex NNK induction group and the vitamin D interventiongroup.Conclusions:（1）Vitamin D has inhibiting effect on the process of malignanttransformation of human bronchial epithelial cells induced bytobacco-specific nitrosamine-NNK.（2）In the later stage of malignantly transform of human bronchialepithelial cells induced by NNK, BMP-2can be used as a detection indexon the lung tumorigenesis induced by NNK.（3）In the midle and later stage of malignantly transform of humanbronchial epithelial cells induced by NNK, COX-2can be used as a detectionindex on the lung tumorigenesis induced by NNK.