title: Rab5a overexpression promoting ovarian cancer cell proliferation may be associated with APPL1-related epidermal growth factor signaling pathway.
abstract: Rab5a is a regulatory guanosine triphosphatase that is associated with the transport and fusion of endocytic vesicles, and participates in regulation of intracellular signaling pathways embraced by cells to adapt to the specific environment. Rab5a is also correlated with lung, stomach, and hepatocellular carcinomas. Here, we detected Rab5a in paraffin-embedded samples of 20 ovarian cysts, 20 benign cystadenomas, and 39 ovarian cancers by immunohistochemistry, and observed that Rab5a expression was significantly higher in ovarian cancer (P = 0.0001). By setting up stable HO-8910 cell lines expressing Rab5a or dominant negative Rab5a (Rab5a:S34N), we found that Rab5a overexpression enhanced the cell growth by promoting G1 into S phase. In contrast, Rab5a:S34N inhibited this process. Additionally, APPL1 (adaptor protein containing PH domain, PTB domain, and Leucine zipper motif), a downstream effector of Rab5a, was also involved in promoting HO-8910 cell cycle progress. But this function was blocked by Rab5a:S34N. Laser scanning confocal microscopy represented the colocalization of APPL1 and Rab5a in the plasmolemma, which changed with the time of epidermal growth factor (EGF) stimulation. We also found APPL1 could transfer from the membranes into the nucleus where it interacted with NuRD/MeCP1 (the nucleosome remodeling and histone deacetylase multiprotein complex). NuRD is reported to be involved in the deacetylation of histone H3 and H4 to regulate nuclear transcription. So Rab5a promoted proliferation of ovarian cancer cells, which may be associated with the APPL1-related epidermal growth factor signaling pathway.
authors.affiliation: Department of Laboratory Medicine, Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhao
authors.forename: Xiang-Fan
authors.initials: XF
authors.lastname: Liu
authors.forename: Hua-Cheng
authors.initials: HC
authors.lastname: Wu
authors.forename: Shu-Biao
authors.initials: SB
authors.lastname: Zou
authors.forename: Jia-Yi
authors.initials: JY
authors.lastname: Wang
authors.forename: Pei-Hua
authors.initials: PH
authors.lastname: Ni
authors.forename: Xin-Hua
authors.initials: XH
authors.lastname: Chen
authors.forename: Qi-Shi
authors.initials: QS
authors.lastname: Fan
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000502:physiology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002453:Cell Cycle; D049109:Cell Proliferation; D019938:Cyclin D1 / Q000235:genetics; D004815:Epidermal Growth Factor / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000473:pathology*; D015398:Signal Transduction / Q000502:physiology*; D020696:rab5 GTP-Binding Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: C464801:APPL1 protein, human; D048868:Adaptor Proteins, Signal Transducing; C530104:CCND1 protein, human; D019938:Cyclin D1; D004815:Epidermal Growth Factor; D020696:rab5 GTP-Binding Proteins
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