Subjects: Biology >> Biophysics >> Cell Biology submitted time 2016-05-15
Zhang, Dongdong
Zhang, Weimin
Li, Dan
Fu, Ming
Zhan, Qimin
Zhang, Dongdong
Zhang, Weimin
Li, Dan
Fu, Ming
Zhan, Qimin
Zhang, Dongdong
Chen, Runsheng
Zhan, Qimin
Abstract： GADD45A is a TP53-regulated and DNA damage-inducible tumor suppressor protein, which regulates cell cycle arrest, apoptosis, and DNA repair, and inhibits tumor growth and angiogenesis. However, the function of GADD45A in autophagy remains unknown. In this report, we demonstrate that GADD45A plays an important role in regulating the process of autophagy. GADD45A is able to decrease LC3-II expression and numbers of autophagosomes in mouse tissues and different cancer cell lines. Using bafilomycin A(1) treatment, we have observed that GADD45A regulates autophagosome initiation. Likely, GADD45A inhibition of autophagy is through its influence on the interaction between BECN1 and PIK3C3. Immunoprecipitation and GST affinity isolation assays exhibit that GADD45A directly interacts with BECN1, and in turn dissociates the BECN1-PIK3C3 complex. Furthermore, we have mapped the 71 to 81 amino acids of the GADD45A protein that are necessary for the GADD45A interaction with BECN1. Knockdown of BECN1 can abolish autophagy alterations induced by GADD45A. Taken together, these findings provide the novel evidence that GADD45A inhibits autophagy via impairing the BECN1-PIK3C3 complex formation.
Peer Review Status:
Awaiting Review
Subjects: Biology >> Biophysics >> Genetics & Heredity submitted time 2016-05-11
Cui, Yingying
Gao, Dan
Linghu, Enqiang
Guo, Mingzhou
Cui, Yingying
Zhan, Qimin
Zhan, Qimin
Chen, Runsheng
Brock, Malcolm V.
Herman, James G.
Abstract： Aim: To examine epigenetic changes and the function of HOXA11 in human gastric cancer (GC). Materials & methods: Seven GC cell lines, five cases of normal gastric mucosa and 112 cases primary GC samples were used in this study. Results: Expression of HOXA11 and lack of promoter region methylation were found in NCI-N87, MKN45, BGC823 and HGC27 cells. Loss of expression and complete methylation were found in AGS gastric cancer cells. Reduced expression and partial methylation were found in MGC803 and SGC7901 cells. Restoration of HOXA11 expression was induced by 5-aza-2'-deoxycytidine. HOXA11 was methylated in 81.25% (91/112) of primary GCs. The presence of methylation was associated with male gender, tumor size, tumor differentiation and lymph node metastasis (all p < 0.05). Restoration of HOXA11 expression reduced cell proliferation, invasion, migration and induced apoptosis and G2/M phase arrest. HOXA11 was found to inhibit Wnt signaling by upregulating NKD1 expression. Conclusion: Epigenetic silencing of HOXA11 promotes GC proliferation, migration and invasion through activation of Wnt signaling.
Peer Review Status:Awaiting Review
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