title: Sterigmatocystin induces G1 arrest in primary human esophageal epithelial cells but induces G2 arrest in immortalized cells: key mechanistic differences in these two models.
abstract: Sterigmatocystin (ST), a mycotoxin commonly found in food and feed commodities, has been classified as a "possible human carcinogen." Our previous studies suggested that ST exposure might be a risk factor for esophageal cancer and that ST may induce DNA damage and G2 phase arrest in immortalized human esophageal epithelial cells (Het-1A). To further confirm and explore the cellular responses of ST in human esophageal epithelia, we comparatively evaluated DNA damage, cell cycle distribution and the relative mechanisms in primary cultured human esophageal epithelial cells (EPC), which represent a more representative model of the in vivo state, and Het-1A cells. In this study, we found that ST could induce DNA damage in both EPC and Het-1A cells but led to G1 phase arrest in EPC cells and G2 phase arrest in Het-1A cells. Furthermore, our results indicated that the activation of the ATM-Chk2 pathway was involved in ST-induced G1 phase arrest in EPC cells, whereas the p53-p21 pathway activation in ST-induced G2 phase arrest in Het-1A cells. Studies have demonstrated that SV40 large T-antigen (SV40LT) may disturb cell cycle progression by inactivating some of the proteins involved in the G1/S checkpoint. Het-1A is a non-cancerous epithelial cell line immortalized by SV40LT. To evaluate the possible perturbation effect of SV40LT on ST-induced cell cycle disturbance in Het-1A cells, we knocked down SV40LT of Het-1A cells with siRNA and found that under this condition, ST-induced G2 arrest was significantly attenuated, whereas the proportion of cells in the G1 phase was significantly increased. Furthermore, SV40LT-siRNA also inhibited the activation of the p53-p21 signaling pathway induced by ST. In conclusion, our data indicated that ST could induce DNA damage in both primary cultured and immortalized esophageal epithelial cells. In primary human esophageal epithelial cells, ST induced DNA damage and then triggered the ATM-Chk2 pathway, resulting in G1 phase arrest, whereas in SV40LT-immortalized human esophageal epithelial cells, SV40LT-mediated G1 checkpoint inactivation occurred, and ST-DNA damage activated p53-p21 signaling pathway, up-regulating G2/M phase regulatory proteins and finally leading to a G2 phase arrest. Thus, the SV40LT-mediated G1 checkpoint inactivation is responsible for the difference in the cell cycle arrest by ST between immortalized and primary cultured human esophageal epithelial cells.
authors.affiliation: Department of Pathology, The Second Hospital of Hebei Medical University, No. 215, Heping Western Road, Shijiazhuang, Hebei Province, People's Republic of China.
authors.forename: Juan
authors.initials: J
authors.lastname: Wang
authors.affiliation: Laboratory of Pathology, Hebei Medical University, No. 361, Zhongshan Eastern Road, Shijiazhuang, Hebei Province, People's Republic of China.
authors.forename: Shujuan
authors.initials: S
authors.lastname: Huang
authors.affiliation: Laboratory of Pathology, Hebei Medical University, No. 361, Zhongshan Eastern Road, Shijiazhuang, Hebei Province, People's Republic of China.
authors.forename: Lingxiao
authors.initials: L
authors.lastname: Xing
authors.affiliation: Department of Pathology, The Second Hospital of Hebei Medical University, No. 215, Heping Western Road, Shijiazhuang, Hebei Province, People's Republic of China.
authors.forename: Jinfeng
authors.initials: J
authors.lastname: Cui
authors.affiliation: Department of Cardio-Thoracic Surgery, The Fourth Hospital, Hebei Medical University, No. 12, Healthy Road, Shijiazhuang, Hebei Province, People's Republic of China.
authors.forename: Ziqiang
authors.initials: Z
authors.lastname: Tian
authors.affiliation: Laboratory of Pathology, Hebei Medical University, No. 361, Zhongshan Eastern Road, Shijiazhuang, Hebei Province, People's Republic of China.
authors.forename: Haitao
authors.initials: H
authors.lastname: Shen
authors.affiliation: Laboratory of Pathology, Hebei Medical University, No. 361, Zhongshan Eastern Road, Shijiazhuang, Hebei Province, People's Republic of China.
authors.forename: Xiujuan
authors.initials: X
authors.lastname: Jiang
authors.affiliation: Laboratory of Pathology, Hebei Medical University, No. 361, Zhongshan Eastern Road, Shijiazhuang, Hebei Province, People's Republic of China.
authors.forename: Xia
authors.initials: X
authors.lastname: Yan
authors.affiliation: Laboratory of Pathology, Hebei Medical University, No. 361, Zhongshan Eastern Road, Shijiazhuang, Hebei Province, People's Republic of China.
authors.forename: Junling
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Pathology, The Second Hospital of Hebei Medical University, No. 215, Heping Western Road, Shijiazhuang, Hebei Province, People's Republic of China. zhangxianghong2008@163.com.
authors.forename: Xianghong
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000952:Antigens, Polyomavirus Transforming / Q000235:genetics; D002460:Cell Line; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects*; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D004947:Esophagus / Q000166:cytology / Q000187:drug effects*; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006801:Humans; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D013241:Sterigmatocystin / Q000633:toxicity*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D000952:Antigens, Polyomavirus Transforming; D050759:Cyclin-Dependent Kinase Inhibitor p21; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D013241:Sterigmatocystin
keywords: ATM; DNA damage; G1 phase arrest; G2 phase arrest; Human esophageal epithelium; Sterigmatocystin; p53