Together, these results suggest that both the PI3 kinase pathway and the SNX23microtubule sellectchem system are involved in the establishment or maintenance of SNX16 vesicles at cell cortex. SNX16 regulates cell migration but not growth Previous studies Inhibitors,Modulators,Libraries have implicated SNX16 in the signaling pathways such as EGF, BMP and Wnt pathways. Inhibitors,Modulators,Libraries These pathways have diverse functions in regulating pro cesses such as cell survival, proliferation or migration. Our observation that SNX16 is present close to focal adhesions further suggests that it might be involved in cell migration. In order to test this possibility, we first established cell lines stably expressing SNX16 in MCF 7 and HT1080 cells. We compared the migration activity of SNX16 expressing cells to the empty vector infected cells using the Cell Motility HCS Reagent Kit.

We found that ectopic expression of SNX16 reduces the migration of both cells to less than half of the control levels. We compared the growth curve and cell cycle profile between the vector and SNX16 express ing MCF 7 stable cell lines and found that they are not af fected by SNX16 over expression. Together, these results suggest that SNX16 is Inhibitors,Modulators,Libraries involved in cell migration but not growth. SNX16 regulates tumorigenesis of MCF 7 cells MCF 7 is a breast cancer derived cell line that can induce tumor formation when injected subcutaneously into the SCID mice. We investigated whether or not the ectopic expression of SNX16 has an effect on the tumorigenic ac tivity of this cell line. Stable MCF 7 cell lines expressing the empty vector or SNX2 are used as the control.

We injected these cells into the SCID mice, monitored the sizes of the tumors and finally determined the weights of tumors 27 days post inoculation after the dissection of tu mors. We found that the ectopic expression of SNX16 but not SNX2 significantly reduces the tumor formation activity of MCF 7 cells. To gether, our results suggest that SNX16 is a negative Inhibitors,Modulators,Libraries regu lator of cell migration and tumorigenesis in vivo. Discussion SNX16 contains a PX domain and a C terminal coiled coil domain, which is unique among SNX family members. Previous biochemical studies demonstrate that the PX do main of SNX16 preferentially binds to PI3P. This binding is required for the endosome association of SNX16 since inhibition of PI3P synthesis by wortmannin, an inhibitor of PI3 kinase, Inhibitors,Modulators,Libraries results in the diffused distribution of SNX16 in the cytosol of COS 7 cells.

The intracellular localization of SNX16 has been investigated in several cell lines. however, the exact distribution pattern of SNX16 appears to be cell type dependent. It has been attributed to EEA1 positive, TFR positive or Rab7 and Lamp1 positive the following site dependent on the cell lines used. We demonstrate here that SNX16 vesicles are aggregated near focal adhesions at cell cortex in a variety of cell lines as well as in vivo.