title: Humic acid induced growth retardation in a sertoli cell line, TM4.
abstract: Humic acid (HA) is a fluorescent deep brown organic, polymeric compound composed of phenolic acid. Intraperitoneal injection of HA in rats induced testicular morphological changes including degeneration of the seminiferous tubule, reduction in the number of Sertoli cells and spermatogonia, and a loss of spermatids. It was suggested that Sertoli cells may be involved in the progression of testicular atrophy. In this study, we used a mouse Sertoli cell Line, TM4, to investigate the effect of HA on Sertoli cells and the mechanism of the testicular atrophy induced by HA. We found that the cell growth of TM4 cells were reduced in 1 to 4 days of HA exposure. FACScan analysis of the DNA content of HA-treated TM4 cells revealed that there was no sub-G1 peak, indicating that the TM4 cells did not commit to the programmed cell death. However, a large proportion of TM4 cells were arrested at the G1 phase. The percentage of TM4 cells at the G1 phase increased from 36% to 84% after HA treatment for 4 days. Western blot assay of HA-treated TM4 cells showed that the expression of cyclin D1 protein decreased while the expression of p27kiP1 protein increased. These results suggest that HA-induced testicular atrophy is linked in part to an inhibitory effect on the growth of Sertoli cells. This model may be useful in investigation of environmental agents inducing testicular atrophy.
authors.affiliation: Department of Biochemistry, College of Medicine, National Taiwan University, Taipei, ROC.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Chen
authors.forename: S
authors.initials: S
authors.lastname: Lin-Chao
authors.forename: T S
authors.initials: TS
authors.lastname: Huang
authors.forename: M L
authors.initials: ML
authors.lastname: Yang
authors.forename: F J
authors.initials: FJ
authors.lastname: Lu
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002452:Cell Count; D018797:Cell Cycle Proteins / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D019938:Cyclin D1 / Q000096:biosynthesis; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004247:DNA / Q000096:biosynthesis; D005434:Flow Cytometry; D016193:G1 Phase / Q000187:drug effects; D006812:Humic Substances / Q000633:toxicity*; D008297:Male; D051379:Mice; D012708:Sertoli Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D025521:Tumor Suppressor Proteins
chemical_list: C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D006812:Humic Substances; D025521:Tumor Suppressor Proteins; D019938:Cyclin D1; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004247:DNA