Girdin locates in centrosome and midbody and plays an important role in cell division.

Girdin is a downstream effector of epidermal growth factor receptor (EGFR)-AKT and interacts with actin and microtubule. Increasing evidence confirmed that Girdin played an important role in cell migration. Here we report that Girdin also regulates cell division. Overexpression or suppression of Girdin leads to attenuated cell proliferation. Imaging of mitotic cells revealed that Girdin is located in the cell division apparatus such as centrosome and midbody. The sub-cellular localization of Girdin was dependent on the domains, which interacted with actin or microtubules. Overexpression of Girdin lead to increased centrosome splitting and amplification. In addition, data show that pAKT also locates in both the centrosome and midbody, indicating the regulating role of AKT in Girdin-mediated cell division. To elucidate the effect of Girdin on tumor growth in vivo, HeLa cells infected with retrovirus harboring either control or Girdin shRNAs were injected subcutaneously into the immunocompromised nude mice. Downregulation of Girdin by shRNA markedly inhibited the cell growth of subcutaneously transplanted tumors in nude mice. These data demonstrate that Girdin is important for efficient cell division. Taking our previous data into consideration, we speculate that Girdin regulates both cell division and cell migration through cytoskeletal molecules.

[Effects of honokiol on proliferation and apoptosis of human cervical carcinoma cell line Hela in vitro].

OBJECTIVE: To assess the effects of honokiol on proliferation and apoptosis of human cervical carcinoma cell line Hela in vitro. METHODS: Cultured HeLa cells were treated with different concentrations of honokiol for the varieties of period (24, 48, 72, 96 h). Cell proliferation was assessed by MTT colorimetric assay. Cell apoptosis was determined by flow cytometry (FCM), Hoechst 33258 fluorescent staining and DNA ladder respectively. RESULTS: MTT assay demonstrated that the proliferation of Hela cells were suppressed significantly by honokiol in dose-and time-dependent manner. FCM analysis showed that the apoptosis rates of Hela cells treated with 10 microg/mL and 20 microg/mL honokiol for 24 h were 22.5% and 62.2%, respectively, while that of the control group cells was 8.7%. After treatment with honokiol, typically morphologic changes of apoptosis were observed by Hoechst 33258 fluorescence staining; Genomic DNA from Hela cells treated with honokiol displayed a characteristic ladder pattern on agarose gel electrophoresis. CONCLUSION: honokiol can inhibit the proliferation and induce apoptosis of human cervical carcinoma cell line Hela.