RESUMO
With a propensity to invade the dermal lymphatic vessels of the skin overlying the breast and readily metastasize, inflammatory breast cancer (IBC) is arguably the deadliest form of breast cancer. We previously reported that caveolin-1 is overexpressed in IBC and that RhoC GTPase is a metastatic switch responsible for the invasive phenotype. RhoC-driven invasion requires phosphorylation by Akt1. Using a reliable IBC cell line we set out to determine if caveolin-1 expression affects RhoC-mediated IBC invasion. Caveolin-1 was down regulated by introduction of siRNA or a caveolin scaffolding domain. The ability of the cells to invade was tested and the status of Akt1 and RhoC GTPase examined. IBC cell invasion is significantly decreased when caveolin-1 is down regulated. Activation of Akt1 is decreased when caveolin-1 is down regulated, leading to decreased phosphorylation of RhoC GTPase. Thus, we report here that caveolin-1 overexpression mediates IBC cell invasion through activation Akt1, which phosphorylates RhoC GTPase.
Assuntos
Caveolina 1/metabolismo , Neoplasias Inflamatórias Mamárias/metabolismo , Neoplasias Inflamatórias Mamárias/patologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas rho de Ligação ao GTP/metabolismo , Animais , Caveolina 1/genética , Linhagem Celular , Linhagem Celular Tumoral , Proliferação de Células/genética , Proliferação de Células/efeitos da radiação , Sobrevivência Celular/genética , Sobrevivência Celular/fisiologia , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Neoplasias Inflamatórias Mamárias/genética , Camundongos , Invasividade Neoplásica/genética , Invasividade Neoplásica/patologia , Proteínas Proto-Oncogênicas c-akt/genética , RNA Interferente Pequeno , Proteínas rho de Ligação ao GTP/genéticaRESUMO
Protrusion formation is the first step that precedes cell movement of motile cells. Spatial control of actin polymerization is necessary to achieve directional protrusion during cell migration. Here we show that the spatial coordinators p190RhoGEF and p190RhoGAP regulate actin polymerization during leading edge protrusions by regulating the actin barbed end distribution and amplitude. The distribution of RhoC activity and proper balance of cofilin activation achieved by p190RhoGEF and p190RhoGAP determines the direction of final protrusive activity. These findings provide a new insight into the dynamic plasticity in the amplitude and distribution of barbed ends, which can be modulated by fine-tuning RhoC activity by upstream GEFs and GAPs for directed cell motility.
Assuntos
Citoesqueleto de Actina/ultraestrutura , Actinas/metabolismo , Actinas/ultraestrutura , Proteínas rho de Ligação ao GTP/metabolismo , Citoesqueleto de Actina/química , Citoesqueleto de Actina/patologia , Animais , Linhagem Celular Tumoral , Movimento Celular/fisiologia , Quimiotaxia/fisiologia , Neoplasias Mamárias Experimentais/patologia , Ratos , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Transfecção , Proteínas rho de Ligação ao GTP/química , Proteínas rho de Ligação ao GTP/genéticaRESUMO
This study investigated the effect of RhoC GTPase on the proliferation and metastasis of cervical cancer cells, SiHa cells, in vitro. RhoC siRNA was introduced into SiHa cells to silence the RhoC gene. The mRNA and protein expression of RhoC, before and after RhoC siRNA transfection,was examined by RT-PCR and Western blotting, respectively. The proliferation and apoptosis of SiHa cells were examined by MTT assay and flow cytometry (FACS), respectively. Adhesive rate was evaluated by Matrigel adhesive assay, and the invasive capability and migration capability were assessed by transwell invasive assay and migration assay, respectively. The results showed that after the RhoC siRNA transfection, the mRNA and protein expression of RhoC was down-regulated in SiHa cells. The down-regulation of RhoC GTPase did not affect the cell proliferation and apoptosis (P>0.05), but it did suppress SiHa cells' adhesion to matrigel (P<0.01), the invasive capability (P<0.01) and the migration capability (P<0.01). It was concluded that RhoC obviously promotes the adhesion, invasion and migration of SiHa cells in vitro, but not proliferation and apoptosis, suggesting that RhoC plays an important rote in the progression in cervical cancer.
