public class User
    {
      public Int32 RegionID { get; set; }
      public IEnumerable<SelectListItem> Regions {get;set;}
    }

 public class Region
    {
        public Int32 RegionID { get; set; }
        public String NameRegion{ get; set; }
    }

  user.Regions = this.GetListRegions(user.RegionID);
  private IEnumerable<SelectListItem> GetListRegions(Int32 SelectedIDRegion)
        {
             List<Region> regions = du.SelectRegions();
            IEnumerable<SelectListItem> _regions = regions.Select(x => new SelectListItem
            {
                Selected = x.RegionID==SelectedIDRegion,
                Text = x.NameRegion,
                Value = x.RegionID.ToString()
            });
            return _regions;

        }

  <tr><td>Регион</td><td> @Html.DropDownListFor(x=>x.RegionID, Model.Regions, new { @class = "ddl" })</td></tr>

[HttpPost]
        public ActionResult UpdateProfileClient(User user)
        {
            if (ModelState.IsValid)
            {
                DalUser du = new DalUser(ConfigurationManager.ConnectionStrings["connect"].ConnectionString);
                du.UpdateClientUser(user);
                Session["User"] = user;
                ViewBag.SussecUpdate = "Данные успешно обновлены!";
                return View("MyProfileClient", user);
            }
           }